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IMPERFECTIONS IN SOLIDS
Kaiser Rex N PamaMerbounne B Miomio
Why study IMPERFECTIONS IN SOLIDS
Introduction
It has been tacitly assumed that perfect order exists throughout crystalline materials on an atomic scale However such an idealised solid does not exist all contain large numbers of various defects or IMPERFECTIONS
Crystalline defect refers to a lattice irregularity having one or more of its dimensions on the order of an atomic diameter
Point Defects
Vacancy
The simplest of the point defects is a vacancy or vacant lattice site one normally occupied from which an atom is missing
The equilibrium number of vacancies Nv for a
given quantity of material depends on and increases with temperature according to
N is the total number of atomic sites
Qv is the energy required for the formation of a vacancy
T is the absolute temperature in kelvins
k is the gas or Boltzmannrsquos constant(138 x 10-231113090 Jatom K or 862 x 10-51113090eVatom K)
Self-interstitial
A self-interstitial is an atom from the crystal that is crowded into an interstitial site a small void space that under ordinary circumstances is not occupied
IMPURITIES IN SOLIDS
Impurity or foreign atoms will always be present and some will exist as crystalline point defects
Most familiar metals are not highly pure rather they are alloys in which impurity atoms have been added intentionally to impart specific characteristics to the material
The addition of impurity atoms to a metal will result in the formation of a solid solution andor a new second phase
Solid Solutions
A solid solution forms when as the solute atoms are added to the host material the crystal structure is maintained and no new structures are formed
Impurity point defects are found in solid solutions of which there are two types substitutional and interstitial
Substitutional Type
For the substitutional type solute or impurity atoms replace or substitute for the host atoms
Several features of the solute and solvent atoms determine the degree to which the former dissolves in the latter as follows
Atomic Size Factor
Crystal Structure
Electronegativity
Valences
Interstitial Type
For interstitial solid solutions impurity atoms fill the voids or interstices among the host atoms
SPECIFICATION OF COMPOSITION
It is often necessary to express the composition (or concentration)3 of an alloy in terms of its constituent elements The two most common ways to specify composition are weight (or mass) percent and atom percent
Weight Percent (wt)
The basis for weight percent (wt) is the weight of a particular element relative to the total alloy weight
Computation of weight percent
(for a two-element alloy)
Atom Percent (at)
The basis for atom percent (at) calculations is the number of moles of an element in relation to the total moles of the elements in the alloy
Computation of atom percent (for a two-element alloy) Where
mrsquo1- mass (g)A1- atomic weight
Composition Conversions
Conversion of weight percent to atom percent
(for a two-element alloy)
Conversion of atom percent to weight percent
(for a two- element alloy)
Composition Conversions
Conversion of weight percent to mass per unit
volume (for a two- element alloy)
Computation of density (for a two-
element metal alloy)
Composition Conversions
Computation of atomic weight (for a two-element metal alloy)
MISCILLANEOUS IMPERFECTIONS
DISLOCATIONS
A dislocation is a linear or one-dimensional defect around which some of the atoms are misaligned
TYPES OF DISLOCATIONS
Edge DislocationScrew DislocationMixed Dislocation
Edge Dislocation
An extra portion of a plane of atoms or half-plane the edge of which terminates within the crystal
Screw Dislocation
May be thought of as being formed by a shear stress that is applied to produce the distortion shown
Dislocationline
Burgers Vector
c
Mixed Dislocation
Most dislocations found in crystalline materials are probably neither pure edge nor pure screw but exhibit components of both types these are termed mixed dislocations
The magnitude and direction of the lattice distortion associated with a dislocation is expressed in terms of a Burgers vector
INTERFACIAL DEFECTS
Interfacial defects are boundaries that have two dimensions and normally separate regions of the materials that have different crystal structures andor crystallographic orientations These imperfections include external surfaces grain boundaries phase boundaries twin boundaries and stacking faults
External Surfaces
One of the most obvious boundaries is the external surface along which the crystal structure terminates Surface atoms are not bonded to the maximum number of nearest neighbors and are therefore in a higher energy state than the atoms at interior positions
Grain Boundaries
The boundary separating two small grains or crystals having different crystallographic orientations in polycrystalline materials
Phase Boundaries
Phase boundaries exist in multiphase materials wherein a different phase exists on each side of the boundary furthermore each of the constituent phases has its own distinctive physical andor chemical characteristics
Twin Boundaries
A twin boundary is a special type of grain boundary across which there is a specific mirror lattice symmetry that is atoms on one side of the boundary are located in mirror-image positions of the atoms on the other side
ATOMIC VIBRATIONS
Every atom in a solid material is vibrating very rapidly about its lattice position within the crystal In a sense these atomic vibrations may be thought of as imperfections or defects
MICROSCOPIC TECHNIQUES
Optical Microscopy
With optical microscopy the light microscope is used to study the microstructure optical and illumination systems are its basic elements
Electron Microscopy
The upper limit to the magnification possible with an optical microscope is approximately 2000 times Consequently some structural elements are too fine or small to permit observation using optical microscopy Under such circumstances the electron microscope which is capable of much higher magnifications may be employed
Grain Size Determination
The grain size is often determined when the properties of a polycrystalline material are under consideration
N the average number of grains per square inch at a magnification of 1001113090X
n represent the grain size number
Why study IMPERFECTIONS IN SOLIDS
Introduction
It has been tacitly assumed that perfect order exists throughout crystalline materials on an atomic scale However such an idealised solid does not exist all contain large numbers of various defects or IMPERFECTIONS
Crystalline defect refers to a lattice irregularity having one or more of its dimensions on the order of an atomic diameter
Point Defects
Vacancy
The simplest of the point defects is a vacancy or vacant lattice site one normally occupied from which an atom is missing
The equilibrium number of vacancies Nv for a
given quantity of material depends on and increases with temperature according to
N is the total number of atomic sites
Qv is the energy required for the formation of a vacancy
T is the absolute temperature in kelvins
k is the gas or Boltzmannrsquos constant(138 x 10-231113090 Jatom K or 862 x 10-51113090eVatom K)
Self-interstitial
A self-interstitial is an atom from the crystal that is crowded into an interstitial site a small void space that under ordinary circumstances is not occupied
IMPURITIES IN SOLIDS
Impurity or foreign atoms will always be present and some will exist as crystalline point defects
Most familiar metals are not highly pure rather they are alloys in which impurity atoms have been added intentionally to impart specific characteristics to the material
The addition of impurity atoms to a metal will result in the formation of a solid solution andor a new second phase
Solid Solutions
A solid solution forms when as the solute atoms are added to the host material the crystal structure is maintained and no new structures are formed
Impurity point defects are found in solid solutions of which there are two types substitutional and interstitial
Substitutional Type
For the substitutional type solute or impurity atoms replace or substitute for the host atoms
Several features of the solute and solvent atoms determine the degree to which the former dissolves in the latter as follows
Atomic Size Factor
Crystal Structure
Electronegativity
Valences
Interstitial Type
For interstitial solid solutions impurity atoms fill the voids or interstices among the host atoms
SPECIFICATION OF COMPOSITION
It is often necessary to express the composition (or concentration)3 of an alloy in terms of its constituent elements The two most common ways to specify composition are weight (or mass) percent and atom percent
Weight Percent (wt)
The basis for weight percent (wt) is the weight of a particular element relative to the total alloy weight
Computation of weight percent
(for a two-element alloy)
Atom Percent (at)
The basis for atom percent (at) calculations is the number of moles of an element in relation to the total moles of the elements in the alloy
Computation of atom percent (for a two-element alloy) Where
mrsquo1- mass (g)A1- atomic weight
Composition Conversions
Conversion of weight percent to atom percent
(for a two-element alloy)
Conversion of atom percent to weight percent
(for a two- element alloy)
Composition Conversions
Conversion of weight percent to mass per unit
volume (for a two- element alloy)
Computation of density (for a two-
element metal alloy)
Composition Conversions
Computation of atomic weight (for a two-element metal alloy)
MISCILLANEOUS IMPERFECTIONS
DISLOCATIONS
A dislocation is a linear or one-dimensional defect around which some of the atoms are misaligned
TYPES OF DISLOCATIONS
Edge DislocationScrew DislocationMixed Dislocation
Edge Dislocation
An extra portion of a plane of atoms or half-plane the edge of which terminates within the crystal
Screw Dislocation
May be thought of as being formed by a shear stress that is applied to produce the distortion shown
Dislocationline
Burgers Vector
c
Mixed Dislocation
Most dislocations found in crystalline materials are probably neither pure edge nor pure screw but exhibit components of both types these are termed mixed dislocations
The magnitude and direction of the lattice distortion associated with a dislocation is expressed in terms of a Burgers vector
INTERFACIAL DEFECTS
Interfacial defects are boundaries that have two dimensions and normally separate regions of the materials that have different crystal structures andor crystallographic orientations These imperfections include external surfaces grain boundaries phase boundaries twin boundaries and stacking faults
External Surfaces
One of the most obvious boundaries is the external surface along which the crystal structure terminates Surface atoms are not bonded to the maximum number of nearest neighbors and are therefore in a higher energy state than the atoms at interior positions
Grain Boundaries
The boundary separating two small grains or crystals having different crystallographic orientations in polycrystalline materials
Phase Boundaries
Phase boundaries exist in multiphase materials wherein a different phase exists on each side of the boundary furthermore each of the constituent phases has its own distinctive physical andor chemical characteristics
Twin Boundaries
A twin boundary is a special type of grain boundary across which there is a specific mirror lattice symmetry that is atoms on one side of the boundary are located in mirror-image positions of the atoms on the other side
ATOMIC VIBRATIONS
Every atom in a solid material is vibrating very rapidly about its lattice position within the crystal In a sense these atomic vibrations may be thought of as imperfections or defects
MICROSCOPIC TECHNIQUES
Optical Microscopy
With optical microscopy the light microscope is used to study the microstructure optical and illumination systems are its basic elements
Electron Microscopy
The upper limit to the magnification possible with an optical microscope is approximately 2000 times Consequently some structural elements are too fine or small to permit observation using optical microscopy Under such circumstances the electron microscope which is capable of much higher magnifications may be employed
Grain Size Determination
The grain size is often determined when the properties of a polycrystalline material are under consideration
N the average number of grains per square inch at a magnification of 1001113090X
n represent the grain size number
Introduction
It has been tacitly assumed that perfect order exists throughout crystalline materials on an atomic scale However such an idealised solid does not exist all contain large numbers of various defects or IMPERFECTIONS
Crystalline defect refers to a lattice irregularity having one or more of its dimensions on the order of an atomic diameter
Point Defects
Vacancy
The simplest of the point defects is a vacancy or vacant lattice site one normally occupied from which an atom is missing
The equilibrium number of vacancies Nv for a
given quantity of material depends on and increases with temperature according to
N is the total number of atomic sites
Qv is the energy required for the formation of a vacancy
T is the absolute temperature in kelvins
k is the gas or Boltzmannrsquos constant(138 x 10-231113090 Jatom K or 862 x 10-51113090eVatom K)
Self-interstitial
A self-interstitial is an atom from the crystal that is crowded into an interstitial site a small void space that under ordinary circumstances is not occupied
IMPURITIES IN SOLIDS
Impurity or foreign atoms will always be present and some will exist as crystalline point defects
Most familiar metals are not highly pure rather they are alloys in which impurity atoms have been added intentionally to impart specific characteristics to the material
The addition of impurity atoms to a metal will result in the formation of a solid solution andor a new second phase
Solid Solutions
A solid solution forms when as the solute atoms are added to the host material the crystal structure is maintained and no new structures are formed
Impurity point defects are found in solid solutions of which there are two types substitutional and interstitial
Substitutional Type
For the substitutional type solute or impurity atoms replace or substitute for the host atoms
Several features of the solute and solvent atoms determine the degree to which the former dissolves in the latter as follows
Atomic Size Factor
Crystal Structure
Electronegativity
Valences
Interstitial Type
For interstitial solid solutions impurity atoms fill the voids or interstices among the host atoms
SPECIFICATION OF COMPOSITION
It is often necessary to express the composition (or concentration)3 of an alloy in terms of its constituent elements The two most common ways to specify composition are weight (or mass) percent and atom percent
Weight Percent (wt)
The basis for weight percent (wt) is the weight of a particular element relative to the total alloy weight
Computation of weight percent
(for a two-element alloy)
Atom Percent (at)
The basis for atom percent (at) calculations is the number of moles of an element in relation to the total moles of the elements in the alloy
Computation of atom percent (for a two-element alloy) Where
mrsquo1- mass (g)A1- atomic weight
Composition Conversions
Conversion of weight percent to atom percent
(for a two-element alloy)
Conversion of atom percent to weight percent
(for a two- element alloy)
Composition Conversions
Conversion of weight percent to mass per unit
volume (for a two- element alloy)
Computation of density (for a two-
element metal alloy)
Composition Conversions
Computation of atomic weight (for a two-element metal alloy)
MISCILLANEOUS IMPERFECTIONS
DISLOCATIONS
A dislocation is a linear or one-dimensional defect around which some of the atoms are misaligned
TYPES OF DISLOCATIONS
Edge DislocationScrew DislocationMixed Dislocation
Edge Dislocation
An extra portion of a plane of atoms or half-plane the edge of which terminates within the crystal
Screw Dislocation
May be thought of as being formed by a shear stress that is applied to produce the distortion shown
Dislocationline
Burgers Vector
c
Mixed Dislocation
Most dislocations found in crystalline materials are probably neither pure edge nor pure screw but exhibit components of both types these are termed mixed dislocations
The magnitude and direction of the lattice distortion associated with a dislocation is expressed in terms of a Burgers vector
INTERFACIAL DEFECTS
Interfacial defects are boundaries that have two dimensions and normally separate regions of the materials that have different crystal structures andor crystallographic orientations These imperfections include external surfaces grain boundaries phase boundaries twin boundaries and stacking faults
External Surfaces
One of the most obvious boundaries is the external surface along which the crystal structure terminates Surface atoms are not bonded to the maximum number of nearest neighbors and are therefore in a higher energy state than the atoms at interior positions
Grain Boundaries
The boundary separating two small grains or crystals having different crystallographic orientations in polycrystalline materials
Phase Boundaries
Phase boundaries exist in multiphase materials wherein a different phase exists on each side of the boundary furthermore each of the constituent phases has its own distinctive physical andor chemical characteristics
Twin Boundaries
A twin boundary is a special type of grain boundary across which there is a specific mirror lattice symmetry that is atoms on one side of the boundary are located in mirror-image positions of the atoms on the other side
ATOMIC VIBRATIONS
Every atom in a solid material is vibrating very rapidly about its lattice position within the crystal In a sense these atomic vibrations may be thought of as imperfections or defects
MICROSCOPIC TECHNIQUES
Optical Microscopy
With optical microscopy the light microscope is used to study the microstructure optical and illumination systems are its basic elements
Electron Microscopy
The upper limit to the magnification possible with an optical microscope is approximately 2000 times Consequently some structural elements are too fine or small to permit observation using optical microscopy Under such circumstances the electron microscope which is capable of much higher magnifications may be employed
Grain Size Determination
The grain size is often determined when the properties of a polycrystalline material are under consideration
N the average number of grains per square inch at a magnification of 1001113090X
n represent the grain size number
Crystalline defect refers to a lattice irregularity having one or more of its dimensions on the order of an atomic diameter
Point Defects
Vacancy
The simplest of the point defects is a vacancy or vacant lattice site one normally occupied from which an atom is missing
The equilibrium number of vacancies Nv for a
given quantity of material depends on and increases with temperature according to
N is the total number of atomic sites
Qv is the energy required for the formation of a vacancy
T is the absolute temperature in kelvins
k is the gas or Boltzmannrsquos constant(138 x 10-231113090 Jatom K or 862 x 10-51113090eVatom K)
Self-interstitial
A self-interstitial is an atom from the crystal that is crowded into an interstitial site a small void space that under ordinary circumstances is not occupied
IMPURITIES IN SOLIDS
Impurity or foreign atoms will always be present and some will exist as crystalline point defects
Most familiar metals are not highly pure rather they are alloys in which impurity atoms have been added intentionally to impart specific characteristics to the material
The addition of impurity atoms to a metal will result in the formation of a solid solution andor a new second phase
Solid Solutions
A solid solution forms when as the solute atoms are added to the host material the crystal structure is maintained and no new structures are formed
Impurity point defects are found in solid solutions of which there are two types substitutional and interstitial
Substitutional Type
For the substitutional type solute or impurity atoms replace or substitute for the host atoms
Several features of the solute and solvent atoms determine the degree to which the former dissolves in the latter as follows
Atomic Size Factor
Crystal Structure
Electronegativity
Valences
Interstitial Type
For interstitial solid solutions impurity atoms fill the voids or interstices among the host atoms
SPECIFICATION OF COMPOSITION
It is often necessary to express the composition (or concentration)3 of an alloy in terms of its constituent elements The two most common ways to specify composition are weight (or mass) percent and atom percent
Weight Percent (wt)
The basis for weight percent (wt) is the weight of a particular element relative to the total alloy weight
Computation of weight percent
(for a two-element alloy)
Atom Percent (at)
The basis for atom percent (at) calculations is the number of moles of an element in relation to the total moles of the elements in the alloy
Computation of atom percent (for a two-element alloy) Where
mrsquo1- mass (g)A1- atomic weight
Composition Conversions
Conversion of weight percent to atom percent
(for a two-element alloy)
Conversion of atom percent to weight percent
(for a two- element alloy)
Composition Conversions
Conversion of weight percent to mass per unit
volume (for a two- element alloy)
Computation of density (for a two-
element metal alloy)
Composition Conversions
Computation of atomic weight (for a two-element metal alloy)
MISCILLANEOUS IMPERFECTIONS
DISLOCATIONS
A dislocation is a linear or one-dimensional defect around which some of the atoms are misaligned
TYPES OF DISLOCATIONS
Edge DislocationScrew DislocationMixed Dislocation
Edge Dislocation
An extra portion of a plane of atoms or half-plane the edge of which terminates within the crystal
Screw Dislocation
May be thought of as being formed by a shear stress that is applied to produce the distortion shown
Dislocationline
Burgers Vector
c
Mixed Dislocation
Most dislocations found in crystalline materials are probably neither pure edge nor pure screw but exhibit components of both types these are termed mixed dislocations
The magnitude and direction of the lattice distortion associated with a dislocation is expressed in terms of a Burgers vector
INTERFACIAL DEFECTS
Interfacial defects are boundaries that have two dimensions and normally separate regions of the materials that have different crystal structures andor crystallographic orientations These imperfections include external surfaces grain boundaries phase boundaries twin boundaries and stacking faults
External Surfaces
One of the most obvious boundaries is the external surface along which the crystal structure terminates Surface atoms are not bonded to the maximum number of nearest neighbors and are therefore in a higher energy state than the atoms at interior positions
Grain Boundaries
The boundary separating two small grains or crystals having different crystallographic orientations in polycrystalline materials
Phase Boundaries
Phase boundaries exist in multiphase materials wherein a different phase exists on each side of the boundary furthermore each of the constituent phases has its own distinctive physical andor chemical characteristics
Twin Boundaries
A twin boundary is a special type of grain boundary across which there is a specific mirror lattice symmetry that is atoms on one side of the boundary are located in mirror-image positions of the atoms on the other side
ATOMIC VIBRATIONS
Every atom in a solid material is vibrating very rapidly about its lattice position within the crystal In a sense these atomic vibrations may be thought of as imperfections or defects
MICROSCOPIC TECHNIQUES
Optical Microscopy
With optical microscopy the light microscope is used to study the microstructure optical and illumination systems are its basic elements
Electron Microscopy
The upper limit to the magnification possible with an optical microscope is approximately 2000 times Consequently some structural elements are too fine or small to permit observation using optical microscopy Under such circumstances the electron microscope which is capable of much higher magnifications may be employed
Grain Size Determination
The grain size is often determined when the properties of a polycrystalline material are under consideration
N the average number of grains per square inch at a magnification of 1001113090X
n represent the grain size number
Point Defects
Vacancy
The simplest of the point defects is a vacancy or vacant lattice site one normally occupied from which an atom is missing
The equilibrium number of vacancies Nv for a
given quantity of material depends on and increases with temperature according to
N is the total number of atomic sites
Qv is the energy required for the formation of a vacancy
T is the absolute temperature in kelvins
k is the gas or Boltzmannrsquos constant(138 x 10-231113090 Jatom K or 862 x 10-51113090eVatom K)
Self-interstitial
A self-interstitial is an atom from the crystal that is crowded into an interstitial site a small void space that under ordinary circumstances is not occupied
IMPURITIES IN SOLIDS
Impurity or foreign atoms will always be present and some will exist as crystalline point defects
Most familiar metals are not highly pure rather they are alloys in which impurity atoms have been added intentionally to impart specific characteristics to the material
The addition of impurity atoms to a metal will result in the formation of a solid solution andor a new second phase
Solid Solutions
A solid solution forms when as the solute atoms are added to the host material the crystal structure is maintained and no new structures are formed
Impurity point defects are found in solid solutions of which there are two types substitutional and interstitial
Substitutional Type
For the substitutional type solute or impurity atoms replace or substitute for the host atoms
Several features of the solute and solvent atoms determine the degree to which the former dissolves in the latter as follows
Atomic Size Factor
Crystal Structure
Electronegativity
Valences
Interstitial Type
For interstitial solid solutions impurity atoms fill the voids or interstices among the host atoms
SPECIFICATION OF COMPOSITION
It is often necessary to express the composition (or concentration)3 of an alloy in terms of its constituent elements The two most common ways to specify composition are weight (or mass) percent and atom percent
Weight Percent (wt)
The basis for weight percent (wt) is the weight of a particular element relative to the total alloy weight
Computation of weight percent
(for a two-element alloy)
Atom Percent (at)
The basis for atom percent (at) calculations is the number of moles of an element in relation to the total moles of the elements in the alloy
Computation of atom percent (for a two-element alloy) Where
mrsquo1- mass (g)A1- atomic weight
Composition Conversions
Conversion of weight percent to atom percent
(for a two-element alloy)
Conversion of atom percent to weight percent
(for a two- element alloy)
Composition Conversions
Conversion of weight percent to mass per unit
volume (for a two- element alloy)
Computation of density (for a two-
element metal alloy)
Composition Conversions
Computation of atomic weight (for a two-element metal alloy)
MISCILLANEOUS IMPERFECTIONS
DISLOCATIONS
A dislocation is a linear or one-dimensional defect around which some of the atoms are misaligned
TYPES OF DISLOCATIONS
Edge DislocationScrew DislocationMixed Dislocation
Edge Dislocation
An extra portion of a plane of atoms or half-plane the edge of which terminates within the crystal
Screw Dislocation
May be thought of as being formed by a shear stress that is applied to produce the distortion shown
Dislocationline
Burgers Vector
c
Mixed Dislocation
Most dislocations found in crystalline materials are probably neither pure edge nor pure screw but exhibit components of both types these are termed mixed dislocations
The magnitude and direction of the lattice distortion associated with a dislocation is expressed in terms of a Burgers vector
INTERFACIAL DEFECTS
Interfacial defects are boundaries that have two dimensions and normally separate regions of the materials that have different crystal structures andor crystallographic orientations These imperfections include external surfaces grain boundaries phase boundaries twin boundaries and stacking faults
External Surfaces
One of the most obvious boundaries is the external surface along which the crystal structure terminates Surface atoms are not bonded to the maximum number of nearest neighbors and are therefore in a higher energy state than the atoms at interior positions
Grain Boundaries
The boundary separating two small grains or crystals having different crystallographic orientations in polycrystalline materials
Phase Boundaries
Phase boundaries exist in multiphase materials wherein a different phase exists on each side of the boundary furthermore each of the constituent phases has its own distinctive physical andor chemical characteristics
Twin Boundaries
A twin boundary is a special type of grain boundary across which there is a specific mirror lattice symmetry that is atoms on one side of the boundary are located in mirror-image positions of the atoms on the other side
ATOMIC VIBRATIONS
Every atom in a solid material is vibrating very rapidly about its lattice position within the crystal In a sense these atomic vibrations may be thought of as imperfections or defects
MICROSCOPIC TECHNIQUES
Optical Microscopy
With optical microscopy the light microscope is used to study the microstructure optical and illumination systems are its basic elements
Electron Microscopy
The upper limit to the magnification possible with an optical microscope is approximately 2000 times Consequently some structural elements are too fine or small to permit observation using optical microscopy Under such circumstances the electron microscope which is capable of much higher magnifications may be employed
Grain Size Determination
The grain size is often determined when the properties of a polycrystalline material are under consideration
N the average number of grains per square inch at a magnification of 1001113090X
n represent the grain size number
Vacancy
The simplest of the point defects is a vacancy or vacant lattice site one normally occupied from which an atom is missing
The equilibrium number of vacancies Nv for a
given quantity of material depends on and increases with temperature according to
N is the total number of atomic sites
Qv is the energy required for the formation of a vacancy
T is the absolute temperature in kelvins
k is the gas or Boltzmannrsquos constant(138 x 10-231113090 Jatom K or 862 x 10-51113090eVatom K)
Self-interstitial
A self-interstitial is an atom from the crystal that is crowded into an interstitial site a small void space that under ordinary circumstances is not occupied
IMPURITIES IN SOLIDS
Impurity or foreign atoms will always be present and some will exist as crystalline point defects
Most familiar metals are not highly pure rather they are alloys in which impurity atoms have been added intentionally to impart specific characteristics to the material
The addition of impurity atoms to a metal will result in the formation of a solid solution andor a new second phase
Solid Solutions
A solid solution forms when as the solute atoms are added to the host material the crystal structure is maintained and no new structures are formed
Impurity point defects are found in solid solutions of which there are two types substitutional and interstitial
Substitutional Type
For the substitutional type solute or impurity atoms replace or substitute for the host atoms
Several features of the solute and solvent atoms determine the degree to which the former dissolves in the latter as follows
Atomic Size Factor
Crystal Structure
Electronegativity
Valences
Interstitial Type
For interstitial solid solutions impurity atoms fill the voids or interstices among the host atoms
SPECIFICATION OF COMPOSITION
It is often necessary to express the composition (or concentration)3 of an alloy in terms of its constituent elements The two most common ways to specify composition are weight (or mass) percent and atom percent
Weight Percent (wt)
The basis for weight percent (wt) is the weight of a particular element relative to the total alloy weight
Computation of weight percent
(for a two-element alloy)
Atom Percent (at)
The basis for atom percent (at) calculations is the number of moles of an element in relation to the total moles of the elements in the alloy
Computation of atom percent (for a two-element alloy) Where
mrsquo1- mass (g)A1- atomic weight
Composition Conversions
Conversion of weight percent to atom percent
(for a two-element alloy)
Conversion of atom percent to weight percent
(for a two- element alloy)
Composition Conversions
Conversion of weight percent to mass per unit
volume (for a two- element alloy)
Computation of density (for a two-
element metal alloy)
Composition Conversions
Computation of atomic weight (for a two-element metal alloy)
MISCILLANEOUS IMPERFECTIONS
DISLOCATIONS
A dislocation is a linear or one-dimensional defect around which some of the atoms are misaligned
TYPES OF DISLOCATIONS
Edge DislocationScrew DislocationMixed Dislocation
Edge Dislocation
An extra portion of a plane of atoms or half-plane the edge of which terminates within the crystal
Screw Dislocation
May be thought of as being formed by a shear stress that is applied to produce the distortion shown
Dislocationline
Burgers Vector
c
Mixed Dislocation
Most dislocations found in crystalline materials are probably neither pure edge nor pure screw but exhibit components of both types these are termed mixed dislocations
The magnitude and direction of the lattice distortion associated with a dislocation is expressed in terms of a Burgers vector
INTERFACIAL DEFECTS
Interfacial defects are boundaries that have two dimensions and normally separate regions of the materials that have different crystal structures andor crystallographic orientations These imperfections include external surfaces grain boundaries phase boundaries twin boundaries and stacking faults
External Surfaces
One of the most obvious boundaries is the external surface along which the crystal structure terminates Surface atoms are not bonded to the maximum number of nearest neighbors and are therefore in a higher energy state than the atoms at interior positions
Grain Boundaries
The boundary separating two small grains or crystals having different crystallographic orientations in polycrystalline materials
Phase Boundaries
Phase boundaries exist in multiphase materials wherein a different phase exists on each side of the boundary furthermore each of the constituent phases has its own distinctive physical andor chemical characteristics
Twin Boundaries
A twin boundary is a special type of grain boundary across which there is a specific mirror lattice symmetry that is atoms on one side of the boundary are located in mirror-image positions of the atoms on the other side
ATOMIC VIBRATIONS
Every atom in a solid material is vibrating very rapidly about its lattice position within the crystal In a sense these atomic vibrations may be thought of as imperfections or defects
MICROSCOPIC TECHNIQUES
Optical Microscopy
With optical microscopy the light microscope is used to study the microstructure optical and illumination systems are its basic elements
Electron Microscopy
The upper limit to the magnification possible with an optical microscope is approximately 2000 times Consequently some structural elements are too fine or small to permit observation using optical microscopy Under such circumstances the electron microscope which is capable of much higher magnifications may be employed
Grain Size Determination
The grain size is often determined when the properties of a polycrystalline material are under consideration
N the average number of grains per square inch at a magnification of 1001113090X
n represent the grain size number
The equilibrium number of vacancies Nv for a
given quantity of material depends on and increases with temperature according to
N is the total number of atomic sites
Qv is the energy required for the formation of a vacancy
T is the absolute temperature in kelvins
k is the gas or Boltzmannrsquos constant(138 x 10-231113090 Jatom K or 862 x 10-51113090eVatom K)
Self-interstitial
A self-interstitial is an atom from the crystal that is crowded into an interstitial site a small void space that under ordinary circumstances is not occupied
IMPURITIES IN SOLIDS
Impurity or foreign atoms will always be present and some will exist as crystalline point defects
Most familiar metals are not highly pure rather they are alloys in which impurity atoms have been added intentionally to impart specific characteristics to the material
The addition of impurity atoms to a metal will result in the formation of a solid solution andor a new second phase
Solid Solutions
A solid solution forms when as the solute atoms are added to the host material the crystal structure is maintained and no new structures are formed
Impurity point defects are found in solid solutions of which there are two types substitutional and interstitial
Substitutional Type
For the substitutional type solute or impurity atoms replace or substitute for the host atoms
Several features of the solute and solvent atoms determine the degree to which the former dissolves in the latter as follows
Atomic Size Factor
Crystal Structure
Electronegativity
Valences
Interstitial Type
For interstitial solid solutions impurity atoms fill the voids or interstices among the host atoms
SPECIFICATION OF COMPOSITION
It is often necessary to express the composition (or concentration)3 of an alloy in terms of its constituent elements The two most common ways to specify composition are weight (or mass) percent and atom percent
Weight Percent (wt)
The basis for weight percent (wt) is the weight of a particular element relative to the total alloy weight
Computation of weight percent
(for a two-element alloy)
Atom Percent (at)
The basis for atom percent (at) calculations is the number of moles of an element in relation to the total moles of the elements in the alloy
Computation of atom percent (for a two-element alloy) Where
mrsquo1- mass (g)A1- atomic weight
Composition Conversions
Conversion of weight percent to atom percent
(for a two-element alloy)
Conversion of atom percent to weight percent
(for a two- element alloy)
Composition Conversions
Conversion of weight percent to mass per unit
volume (for a two- element alloy)
Computation of density (for a two-
element metal alloy)
Composition Conversions
Computation of atomic weight (for a two-element metal alloy)
MISCILLANEOUS IMPERFECTIONS
DISLOCATIONS
A dislocation is a linear or one-dimensional defect around which some of the atoms are misaligned
TYPES OF DISLOCATIONS
Edge DislocationScrew DislocationMixed Dislocation
Edge Dislocation
An extra portion of a plane of atoms or half-plane the edge of which terminates within the crystal
Screw Dislocation
May be thought of as being formed by a shear stress that is applied to produce the distortion shown
Dislocationline
Burgers Vector
c
Mixed Dislocation
Most dislocations found in crystalline materials are probably neither pure edge nor pure screw but exhibit components of both types these are termed mixed dislocations
The magnitude and direction of the lattice distortion associated with a dislocation is expressed in terms of a Burgers vector
INTERFACIAL DEFECTS
Interfacial defects are boundaries that have two dimensions and normally separate regions of the materials that have different crystal structures andor crystallographic orientations These imperfections include external surfaces grain boundaries phase boundaries twin boundaries and stacking faults
External Surfaces
One of the most obvious boundaries is the external surface along which the crystal structure terminates Surface atoms are not bonded to the maximum number of nearest neighbors and are therefore in a higher energy state than the atoms at interior positions
Grain Boundaries
The boundary separating two small grains or crystals having different crystallographic orientations in polycrystalline materials
Phase Boundaries
Phase boundaries exist in multiphase materials wherein a different phase exists on each side of the boundary furthermore each of the constituent phases has its own distinctive physical andor chemical characteristics
Twin Boundaries
A twin boundary is a special type of grain boundary across which there is a specific mirror lattice symmetry that is atoms on one side of the boundary are located in mirror-image positions of the atoms on the other side
ATOMIC VIBRATIONS
Every atom in a solid material is vibrating very rapidly about its lattice position within the crystal In a sense these atomic vibrations may be thought of as imperfections or defects
MICROSCOPIC TECHNIQUES
Optical Microscopy
With optical microscopy the light microscope is used to study the microstructure optical and illumination systems are its basic elements
Electron Microscopy
The upper limit to the magnification possible with an optical microscope is approximately 2000 times Consequently some structural elements are too fine or small to permit observation using optical microscopy Under such circumstances the electron microscope which is capable of much higher magnifications may be employed
Grain Size Determination
The grain size is often determined when the properties of a polycrystalline material are under consideration
N the average number of grains per square inch at a magnification of 1001113090X
n represent the grain size number
Self-interstitial
A self-interstitial is an atom from the crystal that is crowded into an interstitial site a small void space that under ordinary circumstances is not occupied
IMPURITIES IN SOLIDS
Impurity or foreign atoms will always be present and some will exist as crystalline point defects
Most familiar metals are not highly pure rather they are alloys in which impurity atoms have been added intentionally to impart specific characteristics to the material
The addition of impurity atoms to a metal will result in the formation of a solid solution andor a new second phase
Solid Solutions
A solid solution forms when as the solute atoms are added to the host material the crystal structure is maintained and no new structures are formed
Impurity point defects are found in solid solutions of which there are two types substitutional and interstitial
Substitutional Type
For the substitutional type solute or impurity atoms replace or substitute for the host atoms
Several features of the solute and solvent atoms determine the degree to which the former dissolves in the latter as follows
Atomic Size Factor
Crystal Structure
Electronegativity
Valences
Interstitial Type
For interstitial solid solutions impurity atoms fill the voids or interstices among the host atoms
SPECIFICATION OF COMPOSITION
It is often necessary to express the composition (or concentration)3 of an alloy in terms of its constituent elements The two most common ways to specify composition are weight (or mass) percent and atom percent
Weight Percent (wt)
The basis for weight percent (wt) is the weight of a particular element relative to the total alloy weight
Computation of weight percent
(for a two-element alloy)
Atom Percent (at)
The basis for atom percent (at) calculations is the number of moles of an element in relation to the total moles of the elements in the alloy
Computation of atom percent (for a two-element alloy) Where
mrsquo1- mass (g)A1- atomic weight
Composition Conversions
Conversion of weight percent to atom percent
(for a two-element alloy)
Conversion of atom percent to weight percent
(for a two- element alloy)
Composition Conversions
Conversion of weight percent to mass per unit
volume (for a two- element alloy)
Computation of density (for a two-
element metal alloy)
Composition Conversions
Computation of atomic weight (for a two-element metal alloy)
MISCILLANEOUS IMPERFECTIONS
DISLOCATIONS
A dislocation is a linear or one-dimensional defect around which some of the atoms are misaligned
TYPES OF DISLOCATIONS
Edge DislocationScrew DislocationMixed Dislocation
Edge Dislocation
An extra portion of a plane of atoms or half-plane the edge of which terminates within the crystal
Screw Dislocation
May be thought of as being formed by a shear stress that is applied to produce the distortion shown
Dislocationline
Burgers Vector
c
Mixed Dislocation
Most dislocations found in crystalline materials are probably neither pure edge nor pure screw but exhibit components of both types these are termed mixed dislocations
The magnitude and direction of the lattice distortion associated with a dislocation is expressed in terms of a Burgers vector
INTERFACIAL DEFECTS
Interfacial defects are boundaries that have two dimensions and normally separate regions of the materials that have different crystal structures andor crystallographic orientations These imperfections include external surfaces grain boundaries phase boundaries twin boundaries and stacking faults
External Surfaces
One of the most obvious boundaries is the external surface along which the crystal structure terminates Surface atoms are not bonded to the maximum number of nearest neighbors and are therefore in a higher energy state than the atoms at interior positions
Grain Boundaries
The boundary separating two small grains or crystals having different crystallographic orientations in polycrystalline materials
Phase Boundaries
Phase boundaries exist in multiphase materials wherein a different phase exists on each side of the boundary furthermore each of the constituent phases has its own distinctive physical andor chemical characteristics
Twin Boundaries
A twin boundary is a special type of grain boundary across which there is a specific mirror lattice symmetry that is atoms on one side of the boundary are located in mirror-image positions of the atoms on the other side
ATOMIC VIBRATIONS
Every atom in a solid material is vibrating very rapidly about its lattice position within the crystal In a sense these atomic vibrations may be thought of as imperfections or defects
MICROSCOPIC TECHNIQUES
Optical Microscopy
With optical microscopy the light microscope is used to study the microstructure optical and illumination systems are its basic elements
Electron Microscopy
The upper limit to the magnification possible with an optical microscope is approximately 2000 times Consequently some structural elements are too fine or small to permit observation using optical microscopy Under such circumstances the electron microscope which is capable of much higher magnifications may be employed
Grain Size Determination
The grain size is often determined when the properties of a polycrystalline material are under consideration
N the average number of grains per square inch at a magnification of 1001113090X
n represent the grain size number
IMPURITIES IN SOLIDS
Impurity or foreign atoms will always be present and some will exist as crystalline point defects
Most familiar metals are not highly pure rather they are alloys in which impurity atoms have been added intentionally to impart specific characteristics to the material
The addition of impurity atoms to a metal will result in the formation of a solid solution andor a new second phase
Solid Solutions
A solid solution forms when as the solute atoms are added to the host material the crystal structure is maintained and no new structures are formed
Impurity point defects are found in solid solutions of which there are two types substitutional and interstitial
Substitutional Type
For the substitutional type solute or impurity atoms replace or substitute for the host atoms
Several features of the solute and solvent atoms determine the degree to which the former dissolves in the latter as follows
Atomic Size Factor
Crystal Structure
Electronegativity
Valences
Interstitial Type
For interstitial solid solutions impurity atoms fill the voids or interstices among the host atoms
SPECIFICATION OF COMPOSITION
It is often necessary to express the composition (or concentration)3 of an alloy in terms of its constituent elements The two most common ways to specify composition are weight (or mass) percent and atom percent
Weight Percent (wt)
The basis for weight percent (wt) is the weight of a particular element relative to the total alloy weight
Computation of weight percent
(for a two-element alloy)
Atom Percent (at)
The basis for atom percent (at) calculations is the number of moles of an element in relation to the total moles of the elements in the alloy
Computation of atom percent (for a two-element alloy) Where
mrsquo1- mass (g)A1- atomic weight
Composition Conversions
Conversion of weight percent to atom percent
(for a two-element alloy)
Conversion of atom percent to weight percent
(for a two- element alloy)
Composition Conversions
Conversion of weight percent to mass per unit
volume (for a two- element alloy)
Computation of density (for a two-
element metal alloy)
Composition Conversions
Computation of atomic weight (for a two-element metal alloy)
MISCILLANEOUS IMPERFECTIONS
DISLOCATIONS
A dislocation is a linear or one-dimensional defect around which some of the atoms are misaligned
TYPES OF DISLOCATIONS
Edge DislocationScrew DislocationMixed Dislocation
Edge Dislocation
An extra portion of a plane of atoms or half-plane the edge of which terminates within the crystal
Screw Dislocation
May be thought of as being formed by a shear stress that is applied to produce the distortion shown
Dislocationline
Burgers Vector
c
Mixed Dislocation
Most dislocations found in crystalline materials are probably neither pure edge nor pure screw but exhibit components of both types these are termed mixed dislocations
The magnitude and direction of the lattice distortion associated with a dislocation is expressed in terms of a Burgers vector
INTERFACIAL DEFECTS
Interfacial defects are boundaries that have two dimensions and normally separate regions of the materials that have different crystal structures andor crystallographic orientations These imperfections include external surfaces grain boundaries phase boundaries twin boundaries and stacking faults
External Surfaces
One of the most obvious boundaries is the external surface along which the crystal structure terminates Surface atoms are not bonded to the maximum number of nearest neighbors and are therefore in a higher energy state than the atoms at interior positions
Grain Boundaries
The boundary separating two small grains or crystals having different crystallographic orientations in polycrystalline materials
Phase Boundaries
Phase boundaries exist in multiphase materials wherein a different phase exists on each side of the boundary furthermore each of the constituent phases has its own distinctive physical andor chemical characteristics
Twin Boundaries
A twin boundary is a special type of grain boundary across which there is a specific mirror lattice symmetry that is atoms on one side of the boundary are located in mirror-image positions of the atoms on the other side
ATOMIC VIBRATIONS
Every atom in a solid material is vibrating very rapidly about its lattice position within the crystal In a sense these atomic vibrations may be thought of as imperfections or defects
MICROSCOPIC TECHNIQUES
Optical Microscopy
With optical microscopy the light microscope is used to study the microstructure optical and illumination systems are its basic elements
Electron Microscopy
The upper limit to the magnification possible with an optical microscope is approximately 2000 times Consequently some structural elements are too fine or small to permit observation using optical microscopy Under such circumstances the electron microscope which is capable of much higher magnifications may be employed
Grain Size Determination
The grain size is often determined when the properties of a polycrystalline material are under consideration
N the average number of grains per square inch at a magnification of 1001113090X
n represent the grain size number
Impurity or foreign atoms will always be present and some will exist as crystalline point defects
Most familiar metals are not highly pure rather they are alloys in which impurity atoms have been added intentionally to impart specific characteristics to the material
The addition of impurity atoms to a metal will result in the formation of a solid solution andor a new second phase
Solid Solutions
A solid solution forms when as the solute atoms are added to the host material the crystal structure is maintained and no new structures are formed
Impurity point defects are found in solid solutions of which there are two types substitutional and interstitial
Substitutional Type
For the substitutional type solute or impurity atoms replace or substitute for the host atoms
Several features of the solute and solvent atoms determine the degree to which the former dissolves in the latter as follows
Atomic Size Factor
Crystal Structure
Electronegativity
Valences
Interstitial Type
For interstitial solid solutions impurity atoms fill the voids or interstices among the host atoms
SPECIFICATION OF COMPOSITION
It is often necessary to express the composition (or concentration)3 of an alloy in terms of its constituent elements The two most common ways to specify composition are weight (or mass) percent and atom percent
Weight Percent (wt)
The basis for weight percent (wt) is the weight of a particular element relative to the total alloy weight
Computation of weight percent
(for a two-element alloy)
Atom Percent (at)
The basis for atom percent (at) calculations is the number of moles of an element in relation to the total moles of the elements in the alloy
Computation of atom percent (for a two-element alloy) Where
mrsquo1- mass (g)A1- atomic weight
Composition Conversions
Conversion of weight percent to atom percent
(for a two-element alloy)
Conversion of atom percent to weight percent
(for a two- element alloy)
Composition Conversions
Conversion of weight percent to mass per unit
volume (for a two- element alloy)
Computation of density (for a two-
element metal alloy)
Composition Conversions
Computation of atomic weight (for a two-element metal alloy)
MISCILLANEOUS IMPERFECTIONS
DISLOCATIONS
A dislocation is a linear or one-dimensional defect around which some of the atoms are misaligned
TYPES OF DISLOCATIONS
Edge DislocationScrew DislocationMixed Dislocation
Edge Dislocation
An extra portion of a plane of atoms or half-plane the edge of which terminates within the crystal
Screw Dislocation
May be thought of as being formed by a shear stress that is applied to produce the distortion shown
Dislocationline
Burgers Vector
c
Mixed Dislocation
Most dislocations found in crystalline materials are probably neither pure edge nor pure screw but exhibit components of both types these are termed mixed dislocations
The magnitude and direction of the lattice distortion associated with a dislocation is expressed in terms of a Burgers vector
INTERFACIAL DEFECTS
Interfacial defects are boundaries that have two dimensions and normally separate regions of the materials that have different crystal structures andor crystallographic orientations These imperfections include external surfaces grain boundaries phase boundaries twin boundaries and stacking faults
External Surfaces
One of the most obvious boundaries is the external surface along which the crystal structure terminates Surface atoms are not bonded to the maximum number of nearest neighbors and are therefore in a higher energy state than the atoms at interior positions
Grain Boundaries
The boundary separating two small grains or crystals having different crystallographic orientations in polycrystalline materials
Phase Boundaries
Phase boundaries exist in multiphase materials wherein a different phase exists on each side of the boundary furthermore each of the constituent phases has its own distinctive physical andor chemical characteristics
Twin Boundaries
A twin boundary is a special type of grain boundary across which there is a specific mirror lattice symmetry that is atoms on one side of the boundary are located in mirror-image positions of the atoms on the other side
ATOMIC VIBRATIONS
Every atom in a solid material is vibrating very rapidly about its lattice position within the crystal In a sense these atomic vibrations may be thought of as imperfections or defects
MICROSCOPIC TECHNIQUES
Optical Microscopy
With optical microscopy the light microscope is used to study the microstructure optical and illumination systems are its basic elements
Electron Microscopy
The upper limit to the magnification possible with an optical microscope is approximately 2000 times Consequently some structural elements are too fine or small to permit observation using optical microscopy Under such circumstances the electron microscope which is capable of much higher magnifications may be employed
Grain Size Determination
The grain size is often determined when the properties of a polycrystalline material are under consideration
N the average number of grains per square inch at a magnification of 1001113090X
n represent the grain size number
The addition of impurity atoms to a metal will result in the formation of a solid solution andor a new second phase
Solid Solutions
A solid solution forms when as the solute atoms are added to the host material the crystal structure is maintained and no new structures are formed
Impurity point defects are found in solid solutions of which there are two types substitutional and interstitial
Substitutional Type
For the substitutional type solute or impurity atoms replace or substitute for the host atoms
Several features of the solute and solvent atoms determine the degree to which the former dissolves in the latter as follows
Atomic Size Factor
Crystal Structure
Electronegativity
Valences
Interstitial Type
For interstitial solid solutions impurity atoms fill the voids or interstices among the host atoms
SPECIFICATION OF COMPOSITION
It is often necessary to express the composition (or concentration)3 of an alloy in terms of its constituent elements The two most common ways to specify composition are weight (or mass) percent and atom percent
Weight Percent (wt)
The basis for weight percent (wt) is the weight of a particular element relative to the total alloy weight
Computation of weight percent
(for a two-element alloy)
Atom Percent (at)
The basis for atom percent (at) calculations is the number of moles of an element in relation to the total moles of the elements in the alloy
Computation of atom percent (for a two-element alloy) Where
mrsquo1- mass (g)A1- atomic weight
Composition Conversions
Conversion of weight percent to atom percent
(for a two-element alloy)
Conversion of atom percent to weight percent
(for a two- element alloy)
Composition Conversions
Conversion of weight percent to mass per unit
volume (for a two- element alloy)
Computation of density (for a two-
element metal alloy)
Composition Conversions
Computation of atomic weight (for a two-element metal alloy)
MISCILLANEOUS IMPERFECTIONS
DISLOCATIONS
A dislocation is a linear or one-dimensional defect around which some of the atoms are misaligned
TYPES OF DISLOCATIONS
Edge DislocationScrew DislocationMixed Dislocation
Edge Dislocation
An extra portion of a plane of atoms or half-plane the edge of which terminates within the crystal
Screw Dislocation
May be thought of as being formed by a shear stress that is applied to produce the distortion shown
Dislocationline
Burgers Vector
c
Mixed Dislocation
Most dislocations found in crystalline materials are probably neither pure edge nor pure screw but exhibit components of both types these are termed mixed dislocations
The magnitude and direction of the lattice distortion associated with a dislocation is expressed in terms of a Burgers vector
INTERFACIAL DEFECTS
Interfacial defects are boundaries that have two dimensions and normally separate regions of the materials that have different crystal structures andor crystallographic orientations These imperfections include external surfaces grain boundaries phase boundaries twin boundaries and stacking faults
External Surfaces
One of the most obvious boundaries is the external surface along which the crystal structure terminates Surface atoms are not bonded to the maximum number of nearest neighbors and are therefore in a higher energy state than the atoms at interior positions
Grain Boundaries
The boundary separating two small grains or crystals having different crystallographic orientations in polycrystalline materials
Phase Boundaries
Phase boundaries exist in multiphase materials wherein a different phase exists on each side of the boundary furthermore each of the constituent phases has its own distinctive physical andor chemical characteristics
Twin Boundaries
A twin boundary is a special type of grain boundary across which there is a specific mirror lattice symmetry that is atoms on one side of the boundary are located in mirror-image positions of the atoms on the other side
ATOMIC VIBRATIONS
Every atom in a solid material is vibrating very rapidly about its lattice position within the crystal In a sense these atomic vibrations may be thought of as imperfections or defects
MICROSCOPIC TECHNIQUES
Optical Microscopy
With optical microscopy the light microscope is used to study the microstructure optical and illumination systems are its basic elements
Electron Microscopy
The upper limit to the magnification possible with an optical microscope is approximately 2000 times Consequently some structural elements are too fine or small to permit observation using optical microscopy Under such circumstances the electron microscope which is capable of much higher magnifications may be employed
Grain Size Determination
The grain size is often determined when the properties of a polycrystalline material are under consideration
N the average number of grains per square inch at a magnification of 1001113090X
n represent the grain size number
Solid Solutions
A solid solution forms when as the solute atoms are added to the host material the crystal structure is maintained and no new structures are formed
Impurity point defects are found in solid solutions of which there are two types substitutional and interstitial
Substitutional Type
For the substitutional type solute or impurity atoms replace or substitute for the host atoms
Several features of the solute and solvent atoms determine the degree to which the former dissolves in the latter as follows
Atomic Size Factor
Crystal Structure
Electronegativity
Valences
Interstitial Type
For interstitial solid solutions impurity atoms fill the voids or interstices among the host atoms
SPECIFICATION OF COMPOSITION
It is often necessary to express the composition (or concentration)3 of an alloy in terms of its constituent elements The two most common ways to specify composition are weight (or mass) percent and atom percent
Weight Percent (wt)
The basis for weight percent (wt) is the weight of a particular element relative to the total alloy weight
Computation of weight percent
(for a two-element alloy)
Atom Percent (at)
The basis for atom percent (at) calculations is the number of moles of an element in relation to the total moles of the elements in the alloy
Computation of atom percent (for a two-element alloy) Where
mrsquo1- mass (g)A1- atomic weight
Composition Conversions
Conversion of weight percent to atom percent
(for a two-element alloy)
Conversion of atom percent to weight percent
(for a two- element alloy)
Composition Conversions
Conversion of weight percent to mass per unit
volume (for a two- element alloy)
Computation of density (for a two-
element metal alloy)
Composition Conversions
Computation of atomic weight (for a two-element metal alloy)
MISCILLANEOUS IMPERFECTIONS
DISLOCATIONS
A dislocation is a linear or one-dimensional defect around which some of the atoms are misaligned
TYPES OF DISLOCATIONS
Edge DislocationScrew DislocationMixed Dislocation
Edge Dislocation
An extra portion of a plane of atoms or half-plane the edge of which terminates within the crystal
Screw Dislocation
May be thought of as being formed by a shear stress that is applied to produce the distortion shown
Dislocationline
Burgers Vector
c
Mixed Dislocation
Most dislocations found in crystalline materials are probably neither pure edge nor pure screw but exhibit components of both types these are termed mixed dislocations
The magnitude and direction of the lattice distortion associated with a dislocation is expressed in terms of a Burgers vector
INTERFACIAL DEFECTS
Interfacial defects are boundaries that have two dimensions and normally separate regions of the materials that have different crystal structures andor crystallographic orientations These imperfections include external surfaces grain boundaries phase boundaries twin boundaries and stacking faults
External Surfaces
One of the most obvious boundaries is the external surface along which the crystal structure terminates Surface atoms are not bonded to the maximum number of nearest neighbors and are therefore in a higher energy state than the atoms at interior positions
Grain Boundaries
The boundary separating two small grains or crystals having different crystallographic orientations in polycrystalline materials
Phase Boundaries
Phase boundaries exist in multiphase materials wherein a different phase exists on each side of the boundary furthermore each of the constituent phases has its own distinctive physical andor chemical characteristics
Twin Boundaries
A twin boundary is a special type of grain boundary across which there is a specific mirror lattice symmetry that is atoms on one side of the boundary are located in mirror-image positions of the atoms on the other side
ATOMIC VIBRATIONS
Every atom in a solid material is vibrating very rapidly about its lattice position within the crystal In a sense these atomic vibrations may be thought of as imperfections or defects
MICROSCOPIC TECHNIQUES
Optical Microscopy
With optical microscopy the light microscope is used to study the microstructure optical and illumination systems are its basic elements
Electron Microscopy
The upper limit to the magnification possible with an optical microscope is approximately 2000 times Consequently some structural elements are too fine or small to permit observation using optical microscopy Under such circumstances the electron microscope which is capable of much higher magnifications may be employed
Grain Size Determination
The grain size is often determined when the properties of a polycrystalline material are under consideration
N the average number of grains per square inch at a magnification of 1001113090X
n represent the grain size number
Substitutional Type
For the substitutional type solute or impurity atoms replace or substitute for the host atoms
Several features of the solute and solvent atoms determine the degree to which the former dissolves in the latter as follows
Atomic Size Factor
Crystal Structure
Electronegativity
Valences
Interstitial Type
For interstitial solid solutions impurity atoms fill the voids or interstices among the host atoms
SPECIFICATION OF COMPOSITION
It is often necessary to express the composition (or concentration)3 of an alloy in terms of its constituent elements The two most common ways to specify composition are weight (or mass) percent and atom percent
Weight Percent (wt)
The basis for weight percent (wt) is the weight of a particular element relative to the total alloy weight
Computation of weight percent
(for a two-element alloy)
Atom Percent (at)
The basis for atom percent (at) calculations is the number of moles of an element in relation to the total moles of the elements in the alloy
Computation of atom percent (for a two-element alloy) Where
mrsquo1- mass (g)A1- atomic weight
Composition Conversions
Conversion of weight percent to atom percent
(for a two-element alloy)
Conversion of atom percent to weight percent
(for a two- element alloy)
Composition Conversions
Conversion of weight percent to mass per unit
volume (for a two- element alloy)
Computation of density (for a two-
element metal alloy)
Composition Conversions
Computation of atomic weight (for a two-element metal alloy)
MISCILLANEOUS IMPERFECTIONS
DISLOCATIONS
A dislocation is a linear or one-dimensional defect around which some of the atoms are misaligned
TYPES OF DISLOCATIONS
Edge DislocationScrew DislocationMixed Dislocation
Edge Dislocation
An extra portion of a plane of atoms or half-plane the edge of which terminates within the crystal
Screw Dislocation
May be thought of as being formed by a shear stress that is applied to produce the distortion shown
Dislocationline
Burgers Vector
c
Mixed Dislocation
Most dislocations found in crystalline materials are probably neither pure edge nor pure screw but exhibit components of both types these are termed mixed dislocations
The magnitude and direction of the lattice distortion associated with a dislocation is expressed in terms of a Burgers vector
INTERFACIAL DEFECTS
Interfacial defects are boundaries that have two dimensions and normally separate regions of the materials that have different crystal structures andor crystallographic orientations These imperfections include external surfaces grain boundaries phase boundaries twin boundaries and stacking faults
External Surfaces
One of the most obvious boundaries is the external surface along which the crystal structure terminates Surface atoms are not bonded to the maximum number of nearest neighbors and are therefore in a higher energy state than the atoms at interior positions
Grain Boundaries
The boundary separating two small grains or crystals having different crystallographic orientations in polycrystalline materials
Phase Boundaries
Phase boundaries exist in multiphase materials wherein a different phase exists on each side of the boundary furthermore each of the constituent phases has its own distinctive physical andor chemical characteristics
Twin Boundaries
A twin boundary is a special type of grain boundary across which there is a specific mirror lattice symmetry that is atoms on one side of the boundary are located in mirror-image positions of the atoms on the other side
ATOMIC VIBRATIONS
Every atom in a solid material is vibrating very rapidly about its lattice position within the crystal In a sense these atomic vibrations may be thought of as imperfections or defects
MICROSCOPIC TECHNIQUES
Optical Microscopy
With optical microscopy the light microscope is used to study the microstructure optical and illumination systems are its basic elements
Electron Microscopy
The upper limit to the magnification possible with an optical microscope is approximately 2000 times Consequently some structural elements are too fine or small to permit observation using optical microscopy Under such circumstances the electron microscope which is capable of much higher magnifications may be employed
Grain Size Determination
The grain size is often determined when the properties of a polycrystalline material are under consideration
N the average number of grains per square inch at a magnification of 1001113090X
n represent the grain size number
Several features of the solute and solvent atoms determine the degree to which the former dissolves in the latter as follows
Atomic Size Factor
Crystal Structure
Electronegativity
Valences
Interstitial Type
For interstitial solid solutions impurity atoms fill the voids or interstices among the host atoms
SPECIFICATION OF COMPOSITION
It is often necessary to express the composition (or concentration)3 of an alloy in terms of its constituent elements The two most common ways to specify composition are weight (or mass) percent and atom percent
Weight Percent (wt)
The basis for weight percent (wt) is the weight of a particular element relative to the total alloy weight
Computation of weight percent
(for a two-element alloy)
Atom Percent (at)
The basis for atom percent (at) calculations is the number of moles of an element in relation to the total moles of the elements in the alloy
Computation of atom percent (for a two-element alloy) Where
mrsquo1- mass (g)A1- atomic weight
Composition Conversions
Conversion of weight percent to atom percent
(for a two-element alloy)
Conversion of atom percent to weight percent
(for a two- element alloy)
Composition Conversions
Conversion of weight percent to mass per unit
volume (for a two- element alloy)
Computation of density (for a two-
element metal alloy)
Composition Conversions
Computation of atomic weight (for a two-element metal alloy)
MISCILLANEOUS IMPERFECTIONS
DISLOCATIONS
A dislocation is a linear or one-dimensional defect around which some of the atoms are misaligned
TYPES OF DISLOCATIONS
Edge DislocationScrew DislocationMixed Dislocation
Edge Dislocation
An extra portion of a plane of atoms or half-plane the edge of which terminates within the crystal
Screw Dislocation
May be thought of as being formed by a shear stress that is applied to produce the distortion shown
Dislocationline
Burgers Vector
c
Mixed Dislocation
Most dislocations found in crystalline materials are probably neither pure edge nor pure screw but exhibit components of both types these are termed mixed dislocations
The magnitude and direction of the lattice distortion associated with a dislocation is expressed in terms of a Burgers vector
INTERFACIAL DEFECTS
Interfacial defects are boundaries that have two dimensions and normally separate regions of the materials that have different crystal structures andor crystallographic orientations These imperfections include external surfaces grain boundaries phase boundaries twin boundaries and stacking faults
External Surfaces
One of the most obvious boundaries is the external surface along which the crystal structure terminates Surface atoms are not bonded to the maximum number of nearest neighbors and are therefore in a higher energy state than the atoms at interior positions
Grain Boundaries
The boundary separating two small grains or crystals having different crystallographic orientations in polycrystalline materials
Phase Boundaries
Phase boundaries exist in multiphase materials wherein a different phase exists on each side of the boundary furthermore each of the constituent phases has its own distinctive physical andor chemical characteristics
Twin Boundaries
A twin boundary is a special type of grain boundary across which there is a specific mirror lattice symmetry that is atoms on one side of the boundary are located in mirror-image positions of the atoms on the other side
ATOMIC VIBRATIONS
Every atom in a solid material is vibrating very rapidly about its lattice position within the crystal In a sense these atomic vibrations may be thought of as imperfections or defects
MICROSCOPIC TECHNIQUES
Optical Microscopy
With optical microscopy the light microscope is used to study the microstructure optical and illumination systems are its basic elements
Electron Microscopy
The upper limit to the magnification possible with an optical microscope is approximately 2000 times Consequently some structural elements are too fine or small to permit observation using optical microscopy Under such circumstances the electron microscope which is capable of much higher magnifications may be employed
Grain Size Determination
The grain size is often determined when the properties of a polycrystalline material are under consideration
N the average number of grains per square inch at a magnification of 1001113090X
n represent the grain size number
Interstitial Type
For interstitial solid solutions impurity atoms fill the voids or interstices among the host atoms
SPECIFICATION OF COMPOSITION
It is often necessary to express the composition (or concentration)3 of an alloy in terms of its constituent elements The two most common ways to specify composition are weight (or mass) percent and atom percent
Weight Percent (wt)
The basis for weight percent (wt) is the weight of a particular element relative to the total alloy weight
Computation of weight percent
(for a two-element alloy)
Atom Percent (at)
The basis for atom percent (at) calculations is the number of moles of an element in relation to the total moles of the elements in the alloy
Computation of atom percent (for a two-element alloy) Where
mrsquo1- mass (g)A1- atomic weight
Composition Conversions
Conversion of weight percent to atom percent
(for a two-element alloy)
Conversion of atom percent to weight percent
(for a two- element alloy)
Composition Conversions
Conversion of weight percent to mass per unit
volume (for a two- element alloy)
Computation of density (for a two-
element metal alloy)
Composition Conversions
Computation of atomic weight (for a two-element metal alloy)
MISCILLANEOUS IMPERFECTIONS
DISLOCATIONS
A dislocation is a linear or one-dimensional defect around which some of the atoms are misaligned
TYPES OF DISLOCATIONS
Edge DislocationScrew DislocationMixed Dislocation
Edge Dislocation
An extra portion of a plane of atoms or half-plane the edge of which terminates within the crystal
Screw Dislocation
May be thought of as being formed by a shear stress that is applied to produce the distortion shown
Dislocationline
Burgers Vector
c
Mixed Dislocation
Most dislocations found in crystalline materials are probably neither pure edge nor pure screw but exhibit components of both types these are termed mixed dislocations
The magnitude and direction of the lattice distortion associated with a dislocation is expressed in terms of a Burgers vector
INTERFACIAL DEFECTS
Interfacial defects are boundaries that have two dimensions and normally separate regions of the materials that have different crystal structures andor crystallographic orientations These imperfections include external surfaces grain boundaries phase boundaries twin boundaries and stacking faults
External Surfaces
One of the most obvious boundaries is the external surface along which the crystal structure terminates Surface atoms are not bonded to the maximum number of nearest neighbors and are therefore in a higher energy state than the atoms at interior positions
Grain Boundaries
The boundary separating two small grains or crystals having different crystallographic orientations in polycrystalline materials
Phase Boundaries
Phase boundaries exist in multiphase materials wherein a different phase exists on each side of the boundary furthermore each of the constituent phases has its own distinctive physical andor chemical characteristics
Twin Boundaries
A twin boundary is a special type of grain boundary across which there is a specific mirror lattice symmetry that is atoms on one side of the boundary are located in mirror-image positions of the atoms on the other side
ATOMIC VIBRATIONS
Every atom in a solid material is vibrating very rapidly about its lattice position within the crystal In a sense these atomic vibrations may be thought of as imperfections or defects
MICROSCOPIC TECHNIQUES
Optical Microscopy
With optical microscopy the light microscope is used to study the microstructure optical and illumination systems are its basic elements
Electron Microscopy
The upper limit to the magnification possible with an optical microscope is approximately 2000 times Consequently some structural elements are too fine or small to permit observation using optical microscopy Under such circumstances the electron microscope which is capable of much higher magnifications may be employed
Grain Size Determination
The grain size is often determined when the properties of a polycrystalline material are under consideration
N the average number of grains per square inch at a magnification of 1001113090X
n represent the grain size number
SPECIFICATION OF COMPOSITION
It is often necessary to express the composition (or concentration)3 of an alloy in terms of its constituent elements The two most common ways to specify composition are weight (or mass) percent and atom percent
Weight Percent (wt)
The basis for weight percent (wt) is the weight of a particular element relative to the total alloy weight
Computation of weight percent
(for a two-element alloy)
Atom Percent (at)
The basis for atom percent (at) calculations is the number of moles of an element in relation to the total moles of the elements in the alloy
Computation of atom percent (for a two-element alloy) Where
mrsquo1- mass (g)A1- atomic weight
Composition Conversions
Conversion of weight percent to atom percent
(for a two-element alloy)
Conversion of atom percent to weight percent
(for a two- element alloy)
Composition Conversions
Conversion of weight percent to mass per unit
volume (for a two- element alloy)
Computation of density (for a two-
element metal alloy)
Composition Conversions
Computation of atomic weight (for a two-element metal alloy)
MISCILLANEOUS IMPERFECTIONS
DISLOCATIONS
A dislocation is a linear or one-dimensional defect around which some of the atoms are misaligned
TYPES OF DISLOCATIONS
Edge DislocationScrew DislocationMixed Dislocation
Edge Dislocation
An extra portion of a plane of atoms or half-plane the edge of which terminates within the crystal
Screw Dislocation
May be thought of as being formed by a shear stress that is applied to produce the distortion shown
Dislocationline
Burgers Vector
c
Mixed Dislocation
Most dislocations found in crystalline materials are probably neither pure edge nor pure screw but exhibit components of both types these are termed mixed dislocations
The magnitude and direction of the lattice distortion associated with a dislocation is expressed in terms of a Burgers vector
INTERFACIAL DEFECTS
Interfacial defects are boundaries that have two dimensions and normally separate regions of the materials that have different crystal structures andor crystallographic orientations These imperfections include external surfaces grain boundaries phase boundaries twin boundaries and stacking faults
External Surfaces
One of the most obvious boundaries is the external surface along which the crystal structure terminates Surface atoms are not bonded to the maximum number of nearest neighbors and are therefore in a higher energy state than the atoms at interior positions
Grain Boundaries
The boundary separating two small grains or crystals having different crystallographic orientations in polycrystalline materials
Phase Boundaries
Phase boundaries exist in multiphase materials wherein a different phase exists on each side of the boundary furthermore each of the constituent phases has its own distinctive physical andor chemical characteristics
Twin Boundaries
A twin boundary is a special type of grain boundary across which there is a specific mirror lattice symmetry that is atoms on one side of the boundary are located in mirror-image positions of the atoms on the other side
ATOMIC VIBRATIONS
Every atom in a solid material is vibrating very rapidly about its lattice position within the crystal In a sense these atomic vibrations may be thought of as imperfections or defects
MICROSCOPIC TECHNIQUES
Optical Microscopy
With optical microscopy the light microscope is used to study the microstructure optical and illumination systems are its basic elements
Electron Microscopy
The upper limit to the magnification possible with an optical microscope is approximately 2000 times Consequently some structural elements are too fine or small to permit observation using optical microscopy Under such circumstances the electron microscope which is capable of much higher magnifications may be employed
Grain Size Determination
The grain size is often determined when the properties of a polycrystalline material are under consideration
N the average number of grains per square inch at a magnification of 1001113090X
n represent the grain size number
It is often necessary to express the composition (or concentration)3 of an alloy in terms of its constituent elements The two most common ways to specify composition are weight (or mass) percent and atom percent
Weight Percent (wt)
The basis for weight percent (wt) is the weight of a particular element relative to the total alloy weight
Computation of weight percent
(for a two-element alloy)
Atom Percent (at)
The basis for atom percent (at) calculations is the number of moles of an element in relation to the total moles of the elements in the alloy
Computation of atom percent (for a two-element alloy) Where
mrsquo1- mass (g)A1- atomic weight
Composition Conversions
Conversion of weight percent to atom percent
(for a two-element alloy)
Conversion of atom percent to weight percent
(for a two- element alloy)
Composition Conversions
Conversion of weight percent to mass per unit
volume (for a two- element alloy)
Computation of density (for a two-
element metal alloy)
Composition Conversions
Computation of atomic weight (for a two-element metal alloy)
MISCILLANEOUS IMPERFECTIONS
DISLOCATIONS
A dislocation is a linear or one-dimensional defect around which some of the atoms are misaligned
TYPES OF DISLOCATIONS
Edge DislocationScrew DislocationMixed Dislocation
Edge Dislocation
An extra portion of a plane of atoms or half-plane the edge of which terminates within the crystal
Screw Dislocation
May be thought of as being formed by a shear stress that is applied to produce the distortion shown
Dislocationline
Burgers Vector
c
Mixed Dislocation
Most dislocations found in crystalline materials are probably neither pure edge nor pure screw but exhibit components of both types these are termed mixed dislocations
The magnitude and direction of the lattice distortion associated with a dislocation is expressed in terms of a Burgers vector
INTERFACIAL DEFECTS
Interfacial defects are boundaries that have two dimensions and normally separate regions of the materials that have different crystal structures andor crystallographic orientations These imperfections include external surfaces grain boundaries phase boundaries twin boundaries and stacking faults
External Surfaces
One of the most obvious boundaries is the external surface along which the crystal structure terminates Surface atoms are not bonded to the maximum number of nearest neighbors and are therefore in a higher energy state than the atoms at interior positions
Grain Boundaries
The boundary separating two small grains or crystals having different crystallographic orientations in polycrystalline materials
Phase Boundaries
Phase boundaries exist in multiphase materials wherein a different phase exists on each side of the boundary furthermore each of the constituent phases has its own distinctive physical andor chemical characteristics
Twin Boundaries
A twin boundary is a special type of grain boundary across which there is a specific mirror lattice symmetry that is atoms on one side of the boundary are located in mirror-image positions of the atoms on the other side
ATOMIC VIBRATIONS
Every atom in a solid material is vibrating very rapidly about its lattice position within the crystal In a sense these atomic vibrations may be thought of as imperfections or defects
MICROSCOPIC TECHNIQUES
Optical Microscopy
With optical microscopy the light microscope is used to study the microstructure optical and illumination systems are its basic elements
Electron Microscopy
The upper limit to the magnification possible with an optical microscope is approximately 2000 times Consequently some structural elements are too fine or small to permit observation using optical microscopy Under such circumstances the electron microscope which is capable of much higher magnifications may be employed
Grain Size Determination
The grain size is often determined when the properties of a polycrystalline material are under consideration
N the average number of grains per square inch at a magnification of 1001113090X
n represent the grain size number
Weight Percent (wt)
The basis for weight percent (wt) is the weight of a particular element relative to the total alloy weight
Computation of weight percent
(for a two-element alloy)
Atom Percent (at)
The basis for atom percent (at) calculations is the number of moles of an element in relation to the total moles of the elements in the alloy
Computation of atom percent (for a two-element alloy) Where
mrsquo1- mass (g)A1- atomic weight
Composition Conversions
Conversion of weight percent to atom percent
(for a two-element alloy)
Conversion of atom percent to weight percent
(for a two- element alloy)
Composition Conversions
Conversion of weight percent to mass per unit
volume (for a two- element alloy)
Computation of density (for a two-
element metal alloy)
Composition Conversions
Computation of atomic weight (for a two-element metal alloy)
MISCILLANEOUS IMPERFECTIONS
DISLOCATIONS
A dislocation is a linear or one-dimensional defect around which some of the atoms are misaligned
TYPES OF DISLOCATIONS
Edge DislocationScrew DislocationMixed Dislocation
Edge Dislocation
An extra portion of a plane of atoms or half-plane the edge of which terminates within the crystal
Screw Dislocation
May be thought of as being formed by a shear stress that is applied to produce the distortion shown
Dislocationline
Burgers Vector
c
Mixed Dislocation
Most dislocations found in crystalline materials are probably neither pure edge nor pure screw but exhibit components of both types these are termed mixed dislocations
The magnitude and direction of the lattice distortion associated with a dislocation is expressed in terms of a Burgers vector
INTERFACIAL DEFECTS
Interfacial defects are boundaries that have two dimensions and normally separate regions of the materials that have different crystal structures andor crystallographic orientations These imperfections include external surfaces grain boundaries phase boundaries twin boundaries and stacking faults
External Surfaces
One of the most obvious boundaries is the external surface along which the crystal structure terminates Surface atoms are not bonded to the maximum number of nearest neighbors and are therefore in a higher energy state than the atoms at interior positions
Grain Boundaries
The boundary separating two small grains or crystals having different crystallographic orientations in polycrystalline materials
Phase Boundaries
Phase boundaries exist in multiphase materials wherein a different phase exists on each side of the boundary furthermore each of the constituent phases has its own distinctive physical andor chemical characteristics
Twin Boundaries
A twin boundary is a special type of grain boundary across which there is a specific mirror lattice symmetry that is atoms on one side of the boundary are located in mirror-image positions of the atoms on the other side
ATOMIC VIBRATIONS
Every atom in a solid material is vibrating very rapidly about its lattice position within the crystal In a sense these atomic vibrations may be thought of as imperfections or defects
MICROSCOPIC TECHNIQUES
Optical Microscopy
With optical microscopy the light microscope is used to study the microstructure optical and illumination systems are its basic elements
Electron Microscopy
The upper limit to the magnification possible with an optical microscope is approximately 2000 times Consequently some structural elements are too fine or small to permit observation using optical microscopy Under such circumstances the electron microscope which is capable of much higher magnifications may be employed
Grain Size Determination
The grain size is often determined when the properties of a polycrystalline material are under consideration
N the average number of grains per square inch at a magnification of 1001113090X
n represent the grain size number
Atom Percent (at)
The basis for atom percent (at) calculations is the number of moles of an element in relation to the total moles of the elements in the alloy
Computation of atom percent (for a two-element alloy) Where
mrsquo1- mass (g)A1- atomic weight
Composition Conversions
Conversion of weight percent to atom percent
(for a two-element alloy)
Conversion of atom percent to weight percent
(for a two- element alloy)
Composition Conversions
Conversion of weight percent to mass per unit
volume (for a two- element alloy)
Computation of density (for a two-
element metal alloy)
Composition Conversions
Computation of atomic weight (for a two-element metal alloy)
MISCILLANEOUS IMPERFECTIONS
DISLOCATIONS
A dislocation is a linear or one-dimensional defect around which some of the atoms are misaligned
TYPES OF DISLOCATIONS
Edge DislocationScrew DislocationMixed Dislocation
Edge Dislocation
An extra portion of a plane of atoms or half-plane the edge of which terminates within the crystal
Screw Dislocation
May be thought of as being formed by a shear stress that is applied to produce the distortion shown
Dislocationline
Burgers Vector
c
Mixed Dislocation
Most dislocations found in crystalline materials are probably neither pure edge nor pure screw but exhibit components of both types these are termed mixed dislocations
The magnitude and direction of the lattice distortion associated with a dislocation is expressed in terms of a Burgers vector
INTERFACIAL DEFECTS
Interfacial defects are boundaries that have two dimensions and normally separate regions of the materials that have different crystal structures andor crystallographic orientations These imperfections include external surfaces grain boundaries phase boundaries twin boundaries and stacking faults
External Surfaces
One of the most obvious boundaries is the external surface along which the crystal structure terminates Surface atoms are not bonded to the maximum number of nearest neighbors and are therefore in a higher energy state than the atoms at interior positions
Grain Boundaries
The boundary separating two small grains or crystals having different crystallographic orientations in polycrystalline materials
Phase Boundaries
Phase boundaries exist in multiphase materials wherein a different phase exists on each side of the boundary furthermore each of the constituent phases has its own distinctive physical andor chemical characteristics
Twin Boundaries
A twin boundary is a special type of grain boundary across which there is a specific mirror lattice symmetry that is atoms on one side of the boundary are located in mirror-image positions of the atoms on the other side
ATOMIC VIBRATIONS
Every atom in a solid material is vibrating very rapidly about its lattice position within the crystal In a sense these atomic vibrations may be thought of as imperfections or defects
MICROSCOPIC TECHNIQUES
Optical Microscopy
With optical microscopy the light microscope is used to study the microstructure optical and illumination systems are its basic elements
Electron Microscopy
The upper limit to the magnification possible with an optical microscope is approximately 2000 times Consequently some structural elements are too fine or small to permit observation using optical microscopy Under such circumstances the electron microscope which is capable of much higher magnifications may be employed
Grain Size Determination
The grain size is often determined when the properties of a polycrystalline material are under consideration
N the average number of grains per square inch at a magnification of 1001113090X
n represent the grain size number
Composition Conversions
Conversion of weight percent to atom percent
(for a two-element alloy)
Conversion of atom percent to weight percent
(for a two- element alloy)
Composition Conversions
Conversion of weight percent to mass per unit
volume (for a two- element alloy)
Computation of density (for a two-
element metal alloy)
Composition Conversions
Computation of atomic weight (for a two-element metal alloy)
MISCILLANEOUS IMPERFECTIONS
DISLOCATIONS
A dislocation is a linear or one-dimensional defect around which some of the atoms are misaligned
TYPES OF DISLOCATIONS
Edge DislocationScrew DislocationMixed Dislocation
Edge Dislocation
An extra portion of a plane of atoms or half-plane the edge of which terminates within the crystal
Screw Dislocation
May be thought of as being formed by a shear stress that is applied to produce the distortion shown
Dislocationline
Burgers Vector
c
Mixed Dislocation
Most dislocations found in crystalline materials are probably neither pure edge nor pure screw but exhibit components of both types these are termed mixed dislocations
The magnitude and direction of the lattice distortion associated with a dislocation is expressed in terms of a Burgers vector
INTERFACIAL DEFECTS
Interfacial defects are boundaries that have two dimensions and normally separate regions of the materials that have different crystal structures andor crystallographic orientations These imperfections include external surfaces grain boundaries phase boundaries twin boundaries and stacking faults
External Surfaces
One of the most obvious boundaries is the external surface along which the crystal structure terminates Surface atoms are not bonded to the maximum number of nearest neighbors and are therefore in a higher energy state than the atoms at interior positions
Grain Boundaries
The boundary separating two small grains or crystals having different crystallographic orientations in polycrystalline materials
Phase Boundaries
Phase boundaries exist in multiphase materials wherein a different phase exists on each side of the boundary furthermore each of the constituent phases has its own distinctive physical andor chemical characteristics
Twin Boundaries
A twin boundary is a special type of grain boundary across which there is a specific mirror lattice symmetry that is atoms on one side of the boundary are located in mirror-image positions of the atoms on the other side
ATOMIC VIBRATIONS
Every atom in a solid material is vibrating very rapidly about its lattice position within the crystal In a sense these atomic vibrations may be thought of as imperfections or defects
MICROSCOPIC TECHNIQUES
Optical Microscopy
With optical microscopy the light microscope is used to study the microstructure optical and illumination systems are its basic elements
Electron Microscopy
The upper limit to the magnification possible with an optical microscope is approximately 2000 times Consequently some structural elements are too fine or small to permit observation using optical microscopy Under such circumstances the electron microscope which is capable of much higher magnifications may be employed
Grain Size Determination
The grain size is often determined when the properties of a polycrystalline material are under consideration
N the average number of grains per square inch at a magnification of 1001113090X
n represent the grain size number
Composition Conversions
Conversion of weight percent to mass per unit
volume (for a two- element alloy)
Computation of density (for a two-
element metal alloy)
Composition Conversions
Computation of atomic weight (for a two-element metal alloy)
MISCILLANEOUS IMPERFECTIONS
DISLOCATIONS
A dislocation is a linear or one-dimensional defect around which some of the atoms are misaligned
TYPES OF DISLOCATIONS
Edge DislocationScrew DislocationMixed Dislocation
Edge Dislocation
An extra portion of a plane of atoms or half-plane the edge of which terminates within the crystal
Screw Dislocation
May be thought of as being formed by a shear stress that is applied to produce the distortion shown
Dislocationline
Burgers Vector
c
Mixed Dislocation
Most dislocations found in crystalline materials are probably neither pure edge nor pure screw but exhibit components of both types these are termed mixed dislocations
The magnitude and direction of the lattice distortion associated with a dislocation is expressed in terms of a Burgers vector
INTERFACIAL DEFECTS
Interfacial defects are boundaries that have two dimensions and normally separate regions of the materials that have different crystal structures andor crystallographic orientations These imperfections include external surfaces grain boundaries phase boundaries twin boundaries and stacking faults
External Surfaces
One of the most obvious boundaries is the external surface along which the crystal structure terminates Surface atoms are not bonded to the maximum number of nearest neighbors and are therefore in a higher energy state than the atoms at interior positions
Grain Boundaries
The boundary separating two small grains or crystals having different crystallographic orientations in polycrystalline materials
Phase Boundaries
Phase boundaries exist in multiphase materials wherein a different phase exists on each side of the boundary furthermore each of the constituent phases has its own distinctive physical andor chemical characteristics
Twin Boundaries
A twin boundary is a special type of grain boundary across which there is a specific mirror lattice symmetry that is atoms on one side of the boundary are located in mirror-image positions of the atoms on the other side
ATOMIC VIBRATIONS
Every atom in a solid material is vibrating very rapidly about its lattice position within the crystal In a sense these atomic vibrations may be thought of as imperfections or defects
MICROSCOPIC TECHNIQUES
Optical Microscopy
With optical microscopy the light microscope is used to study the microstructure optical and illumination systems are its basic elements
Electron Microscopy
The upper limit to the magnification possible with an optical microscope is approximately 2000 times Consequently some structural elements are too fine or small to permit observation using optical microscopy Under such circumstances the electron microscope which is capable of much higher magnifications may be employed
Grain Size Determination
The grain size is often determined when the properties of a polycrystalline material are under consideration
N the average number of grains per square inch at a magnification of 1001113090X
n represent the grain size number
Composition Conversions
Computation of atomic weight (for a two-element metal alloy)
MISCILLANEOUS IMPERFECTIONS
DISLOCATIONS
A dislocation is a linear or one-dimensional defect around which some of the atoms are misaligned
TYPES OF DISLOCATIONS
Edge DislocationScrew DislocationMixed Dislocation
Edge Dislocation
An extra portion of a plane of atoms or half-plane the edge of which terminates within the crystal
Screw Dislocation
May be thought of as being formed by a shear stress that is applied to produce the distortion shown
Dislocationline
Burgers Vector
c
Mixed Dislocation
Most dislocations found in crystalline materials are probably neither pure edge nor pure screw but exhibit components of both types these are termed mixed dislocations
The magnitude and direction of the lattice distortion associated with a dislocation is expressed in terms of a Burgers vector
INTERFACIAL DEFECTS
Interfacial defects are boundaries that have two dimensions and normally separate regions of the materials that have different crystal structures andor crystallographic orientations These imperfections include external surfaces grain boundaries phase boundaries twin boundaries and stacking faults
External Surfaces
One of the most obvious boundaries is the external surface along which the crystal structure terminates Surface atoms are not bonded to the maximum number of nearest neighbors and are therefore in a higher energy state than the atoms at interior positions
Grain Boundaries
The boundary separating two small grains or crystals having different crystallographic orientations in polycrystalline materials
Phase Boundaries
Phase boundaries exist in multiphase materials wherein a different phase exists on each side of the boundary furthermore each of the constituent phases has its own distinctive physical andor chemical characteristics
Twin Boundaries
A twin boundary is a special type of grain boundary across which there is a specific mirror lattice symmetry that is atoms on one side of the boundary are located in mirror-image positions of the atoms on the other side
ATOMIC VIBRATIONS
Every atom in a solid material is vibrating very rapidly about its lattice position within the crystal In a sense these atomic vibrations may be thought of as imperfections or defects
MICROSCOPIC TECHNIQUES
Optical Microscopy
With optical microscopy the light microscope is used to study the microstructure optical and illumination systems are its basic elements
Electron Microscopy
The upper limit to the magnification possible with an optical microscope is approximately 2000 times Consequently some structural elements are too fine or small to permit observation using optical microscopy Under such circumstances the electron microscope which is capable of much higher magnifications may be employed
Grain Size Determination
The grain size is often determined when the properties of a polycrystalline material are under consideration
N the average number of grains per square inch at a magnification of 1001113090X
n represent the grain size number
MISCILLANEOUS IMPERFECTIONS
DISLOCATIONS
A dislocation is a linear or one-dimensional defect around which some of the atoms are misaligned
TYPES OF DISLOCATIONS
Edge DislocationScrew DislocationMixed Dislocation
Edge Dislocation
An extra portion of a plane of atoms or half-plane the edge of which terminates within the crystal
Screw Dislocation
May be thought of as being formed by a shear stress that is applied to produce the distortion shown
Dislocationline
Burgers Vector
c
Mixed Dislocation
Most dislocations found in crystalline materials are probably neither pure edge nor pure screw but exhibit components of both types these are termed mixed dislocations
The magnitude and direction of the lattice distortion associated with a dislocation is expressed in terms of a Burgers vector
INTERFACIAL DEFECTS
Interfacial defects are boundaries that have two dimensions and normally separate regions of the materials that have different crystal structures andor crystallographic orientations These imperfections include external surfaces grain boundaries phase boundaries twin boundaries and stacking faults
External Surfaces
One of the most obvious boundaries is the external surface along which the crystal structure terminates Surface atoms are not bonded to the maximum number of nearest neighbors and are therefore in a higher energy state than the atoms at interior positions
Grain Boundaries
The boundary separating two small grains or crystals having different crystallographic orientations in polycrystalline materials
Phase Boundaries
Phase boundaries exist in multiphase materials wherein a different phase exists on each side of the boundary furthermore each of the constituent phases has its own distinctive physical andor chemical characteristics
Twin Boundaries
A twin boundary is a special type of grain boundary across which there is a specific mirror lattice symmetry that is atoms on one side of the boundary are located in mirror-image positions of the atoms on the other side
ATOMIC VIBRATIONS
Every atom in a solid material is vibrating very rapidly about its lattice position within the crystal In a sense these atomic vibrations may be thought of as imperfections or defects
MICROSCOPIC TECHNIQUES
Optical Microscopy
With optical microscopy the light microscope is used to study the microstructure optical and illumination systems are its basic elements
Electron Microscopy
The upper limit to the magnification possible with an optical microscope is approximately 2000 times Consequently some structural elements are too fine or small to permit observation using optical microscopy Under such circumstances the electron microscope which is capable of much higher magnifications may be employed
Grain Size Determination
The grain size is often determined when the properties of a polycrystalline material are under consideration
N the average number of grains per square inch at a magnification of 1001113090X
n represent the grain size number
DISLOCATIONS
A dislocation is a linear or one-dimensional defect around which some of the atoms are misaligned
TYPES OF DISLOCATIONS
Edge DislocationScrew DislocationMixed Dislocation
Edge Dislocation
An extra portion of a plane of atoms or half-plane the edge of which terminates within the crystal
Screw Dislocation
May be thought of as being formed by a shear stress that is applied to produce the distortion shown
Dislocationline
Burgers Vector
c
Mixed Dislocation
Most dislocations found in crystalline materials are probably neither pure edge nor pure screw but exhibit components of both types these are termed mixed dislocations
The magnitude and direction of the lattice distortion associated with a dislocation is expressed in terms of a Burgers vector
INTERFACIAL DEFECTS
Interfacial defects are boundaries that have two dimensions and normally separate regions of the materials that have different crystal structures andor crystallographic orientations These imperfections include external surfaces grain boundaries phase boundaries twin boundaries and stacking faults
External Surfaces
One of the most obvious boundaries is the external surface along which the crystal structure terminates Surface atoms are not bonded to the maximum number of nearest neighbors and are therefore in a higher energy state than the atoms at interior positions
Grain Boundaries
The boundary separating two small grains or crystals having different crystallographic orientations in polycrystalline materials
Phase Boundaries
Phase boundaries exist in multiphase materials wherein a different phase exists on each side of the boundary furthermore each of the constituent phases has its own distinctive physical andor chemical characteristics
Twin Boundaries
A twin boundary is a special type of grain boundary across which there is a specific mirror lattice symmetry that is atoms on one side of the boundary are located in mirror-image positions of the atoms on the other side
ATOMIC VIBRATIONS
Every atom in a solid material is vibrating very rapidly about its lattice position within the crystal In a sense these atomic vibrations may be thought of as imperfections or defects
MICROSCOPIC TECHNIQUES
Optical Microscopy
With optical microscopy the light microscope is used to study the microstructure optical and illumination systems are its basic elements
Electron Microscopy
The upper limit to the magnification possible with an optical microscope is approximately 2000 times Consequently some structural elements are too fine or small to permit observation using optical microscopy Under such circumstances the electron microscope which is capable of much higher magnifications may be employed
Grain Size Determination
The grain size is often determined when the properties of a polycrystalline material are under consideration
N the average number of grains per square inch at a magnification of 1001113090X
n represent the grain size number
Edge Dislocation
An extra portion of a plane of atoms or half-plane the edge of which terminates within the crystal
Screw Dislocation
May be thought of as being formed by a shear stress that is applied to produce the distortion shown
Dislocationline
Burgers Vector
c
Mixed Dislocation
Most dislocations found in crystalline materials are probably neither pure edge nor pure screw but exhibit components of both types these are termed mixed dislocations
The magnitude and direction of the lattice distortion associated with a dislocation is expressed in terms of a Burgers vector
INTERFACIAL DEFECTS
Interfacial defects are boundaries that have two dimensions and normally separate regions of the materials that have different crystal structures andor crystallographic orientations These imperfections include external surfaces grain boundaries phase boundaries twin boundaries and stacking faults
External Surfaces
One of the most obvious boundaries is the external surface along which the crystal structure terminates Surface atoms are not bonded to the maximum number of nearest neighbors and are therefore in a higher energy state than the atoms at interior positions
Grain Boundaries
The boundary separating two small grains or crystals having different crystallographic orientations in polycrystalline materials
Phase Boundaries
Phase boundaries exist in multiphase materials wherein a different phase exists on each side of the boundary furthermore each of the constituent phases has its own distinctive physical andor chemical characteristics
Twin Boundaries
A twin boundary is a special type of grain boundary across which there is a specific mirror lattice symmetry that is atoms on one side of the boundary are located in mirror-image positions of the atoms on the other side
ATOMIC VIBRATIONS
Every atom in a solid material is vibrating very rapidly about its lattice position within the crystal In a sense these atomic vibrations may be thought of as imperfections or defects
MICROSCOPIC TECHNIQUES
Optical Microscopy
With optical microscopy the light microscope is used to study the microstructure optical and illumination systems are its basic elements
Electron Microscopy
The upper limit to the magnification possible with an optical microscope is approximately 2000 times Consequently some structural elements are too fine or small to permit observation using optical microscopy Under such circumstances the electron microscope which is capable of much higher magnifications may be employed
Grain Size Determination
The grain size is often determined when the properties of a polycrystalline material are under consideration
N the average number of grains per square inch at a magnification of 1001113090X
n represent the grain size number
Screw Dislocation
May be thought of as being formed by a shear stress that is applied to produce the distortion shown
Dislocationline
Burgers Vector
c
Mixed Dislocation
Most dislocations found in crystalline materials are probably neither pure edge nor pure screw but exhibit components of both types these are termed mixed dislocations
The magnitude and direction of the lattice distortion associated with a dislocation is expressed in terms of a Burgers vector
INTERFACIAL DEFECTS
Interfacial defects are boundaries that have two dimensions and normally separate regions of the materials that have different crystal structures andor crystallographic orientations These imperfections include external surfaces grain boundaries phase boundaries twin boundaries and stacking faults
External Surfaces
One of the most obvious boundaries is the external surface along which the crystal structure terminates Surface atoms are not bonded to the maximum number of nearest neighbors and are therefore in a higher energy state than the atoms at interior positions
Grain Boundaries
The boundary separating two small grains or crystals having different crystallographic orientations in polycrystalline materials
Phase Boundaries
Phase boundaries exist in multiphase materials wherein a different phase exists on each side of the boundary furthermore each of the constituent phases has its own distinctive physical andor chemical characteristics
Twin Boundaries
A twin boundary is a special type of grain boundary across which there is a specific mirror lattice symmetry that is atoms on one side of the boundary are located in mirror-image positions of the atoms on the other side
ATOMIC VIBRATIONS
Every atom in a solid material is vibrating very rapidly about its lattice position within the crystal In a sense these atomic vibrations may be thought of as imperfections or defects
MICROSCOPIC TECHNIQUES
Optical Microscopy
With optical microscopy the light microscope is used to study the microstructure optical and illumination systems are its basic elements
Electron Microscopy
The upper limit to the magnification possible with an optical microscope is approximately 2000 times Consequently some structural elements are too fine or small to permit observation using optical microscopy Under such circumstances the electron microscope which is capable of much higher magnifications may be employed
Grain Size Determination
The grain size is often determined when the properties of a polycrystalline material are under consideration
N the average number of grains per square inch at a magnification of 1001113090X
n represent the grain size number
Mixed Dislocation
Most dislocations found in crystalline materials are probably neither pure edge nor pure screw but exhibit components of both types these are termed mixed dislocations
The magnitude and direction of the lattice distortion associated with a dislocation is expressed in terms of a Burgers vector
INTERFACIAL DEFECTS
Interfacial defects are boundaries that have two dimensions and normally separate regions of the materials that have different crystal structures andor crystallographic orientations These imperfections include external surfaces grain boundaries phase boundaries twin boundaries and stacking faults
External Surfaces
One of the most obvious boundaries is the external surface along which the crystal structure terminates Surface atoms are not bonded to the maximum number of nearest neighbors and are therefore in a higher energy state than the atoms at interior positions
Grain Boundaries
The boundary separating two small grains or crystals having different crystallographic orientations in polycrystalline materials
Phase Boundaries
Phase boundaries exist in multiphase materials wherein a different phase exists on each side of the boundary furthermore each of the constituent phases has its own distinctive physical andor chemical characteristics
Twin Boundaries
A twin boundary is a special type of grain boundary across which there is a specific mirror lattice symmetry that is atoms on one side of the boundary are located in mirror-image positions of the atoms on the other side
ATOMIC VIBRATIONS
Every atom in a solid material is vibrating very rapidly about its lattice position within the crystal In a sense these atomic vibrations may be thought of as imperfections or defects
MICROSCOPIC TECHNIQUES
Optical Microscopy
With optical microscopy the light microscope is used to study the microstructure optical and illumination systems are its basic elements
Electron Microscopy
The upper limit to the magnification possible with an optical microscope is approximately 2000 times Consequently some structural elements are too fine or small to permit observation using optical microscopy Under such circumstances the electron microscope which is capable of much higher magnifications may be employed
Grain Size Determination
The grain size is often determined when the properties of a polycrystalline material are under consideration
N the average number of grains per square inch at a magnification of 1001113090X
n represent the grain size number
The magnitude and direction of the lattice distortion associated with a dislocation is expressed in terms of a Burgers vector
INTERFACIAL DEFECTS
Interfacial defects are boundaries that have two dimensions and normally separate regions of the materials that have different crystal structures andor crystallographic orientations These imperfections include external surfaces grain boundaries phase boundaries twin boundaries and stacking faults
External Surfaces
One of the most obvious boundaries is the external surface along which the crystal structure terminates Surface atoms are not bonded to the maximum number of nearest neighbors and are therefore in a higher energy state than the atoms at interior positions
Grain Boundaries
The boundary separating two small grains or crystals having different crystallographic orientations in polycrystalline materials
Phase Boundaries
Phase boundaries exist in multiphase materials wherein a different phase exists on each side of the boundary furthermore each of the constituent phases has its own distinctive physical andor chemical characteristics
Twin Boundaries
A twin boundary is a special type of grain boundary across which there is a specific mirror lattice symmetry that is atoms on one side of the boundary are located in mirror-image positions of the atoms on the other side
ATOMIC VIBRATIONS
Every atom in a solid material is vibrating very rapidly about its lattice position within the crystal In a sense these atomic vibrations may be thought of as imperfections or defects
MICROSCOPIC TECHNIQUES
Optical Microscopy
With optical microscopy the light microscope is used to study the microstructure optical and illumination systems are its basic elements
Electron Microscopy
The upper limit to the magnification possible with an optical microscope is approximately 2000 times Consequently some structural elements are too fine or small to permit observation using optical microscopy Under such circumstances the electron microscope which is capable of much higher magnifications may be employed
Grain Size Determination
The grain size is often determined when the properties of a polycrystalline material are under consideration
N the average number of grains per square inch at a magnification of 1001113090X
n represent the grain size number
INTERFACIAL DEFECTS
Interfacial defects are boundaries that have two dimensions and normally separate regions of the materials that have different crystal structures andor crystallographic orientations These imperfections include external surfaces grain boundaries phase boundaries twin boundaries and stacking faults
External Surfaces
One of the most obvious boundaries is the external surface along which the crystal structure terminates Surface atoms are not bonded to the maximum number of nearest neighbors and are therefore in a higher energy state than the atoms at interior positions
Grain Boundaries
The boundary separating two small grains or crystals having different crystallographic orientations in polycrystalline materials
Phase Boundaries
Phase boundaries exist in multiphase materials wherein a different phase exists on each side of the boundary furthermore each of the constituent phases has its own distinctive physical andor chemical characteristics
Twin Boundaries
A twin boundary is a special type of grain boundary across which there is a specific mirror lattice symmetry that is atoms on one side of the boundary are located in mirror-image positions of the atoms on the other side
ATOMIC VIBRATIONS
Every atom in a solid material is vibrating very rapidly about its lattice position within the crystal In a sense these atomic vibrations may be thought of as imperfections or defects
MICROSCOPIC TECHNIQUES
Optical Microscopy
With optical microscopy the light microscope is used to study the microstructure optical and illumination systems are its basic elements
Electron Microscopy
The upper limit to the magnification possible with an optical microscope is approximately 2000 times Consequently some structural elements are too fine or small to permit observation using optical microscopy Under such circumstances the electron microscope which is capable of much higher magnifications may be employed
Grain Size Determination
The grain size is often determined when the properties of a polycrystalline material are under consideration
N the average number of grains per square inch at a magnification of 1001113090X
n represent the grain size number
Interfacial defects are boundaries that have two dimensions and normally separate regions of the materials that have different crystal structures andor crystallographic orientations These imperfections include external surfaces grain boundaries phase boundaries twin boundaries and stacking faults
External Surfaces
One of the most obvious boundaries is the external surface along which the crystal structure terminates Surface atoms are not bonded to the maximum number of nearest neighbors and are therefore in a higher energy state than the atoms at interior positions
Grain Boundaries
The boundary separating two small grains or crystals having different crystallographic orientations in polycrystalline materials
Phase Boundaries
Phase boundaries exist in multiphase materials wherein a different phase exists on each side of the boundary furthermore each of the constituent phases has its own distinctive physical andor chemical characteristics
Twin Boundaries
A twin boundary is a special type of grain boundary across which there is a specific mirror lattice symmetry that is atoms on one side of the boundary are located in mirror-image positions of the atoms on the other side
ATOMIC VIBRATIONS
Every atom in a solid material is vibrating very rapidly about its lattice position within the crystal In a sense these atomic vibrations may be thought of as imperfections or defects
MICROSCOPIC TECHNIQUES
Optical Microscopy
With optical microscopy the light microscope is used to study the microstructure optical and illumination systems are its basic elements
Electron Microscopy
The upper limit to the magnification possible with an optical microscope is approximately 2000 times Consequently some structural elements are too fine or small to permit observation using optical microscopy Under such circumstances the electron microscope which is capable of much higher magnifications may be employed
Grain Size Determination
The grain size is often determined when the properties of a polycrystalline material are under consideration
N the average number of grains per square inch at a magnification of 1001113090X
n represent the grain size number
External Surfaces
One of the most obvious boundaries is the external surface along which the crystal structure terminates Surface atoms are not bonded to the maximum number of nearest neighbors and are therefore in a higher energy state than the atoms at interior positions
Grain Boundaries
The boundary separating two small grains or crystals having different crystallographic orientations in polycrystalline materials
Phase Boundaries
Phase boundaries exist in multiphase materials wherein a different phase exists on each side of the boundary furthermore each of the constituent phases has its own distinctive physical andor chemical characteristics
Twin Boundaries
A twin boundary is a special type of grain boundary across which there is a specific mirror lattice symmetry that is atoms on one side of the boundary are located in mirror-image positions of the atoms on the other side
ATOMIC VIBRATIONS
Every atom in a solid material is vibrating very rapidly about its lattice position within the crystal In a sense these atomic vibrations may be thought of as imperfections or defects
MICROSCOPIC TECHNIQUES
Optical Microscopy
With optical microscopy the light microscope is used to study the microstructure optical and illumination systems are its basic elements
Electron Microscopy
The upper limit to the magnification possible with an optical microscope is approximately 2000 times Consequently some structural elements are too fine or small to permit observation using optical microscopy Under such circumstances the electron microscope which is capable of much higher magnifications may be employed
Grain Size Determination
The grain size is often determined when the properties of a polycrystalline material are under consideration
N the average number of grains per square inch at a magnification of 1001113090X
n represent the grain size number
Grain Boundaries
The boundary separating two small grains or crystals having different crystallographic orientations in polycrystalline materials
Phase Boundaries
Phase boundaries exist in multiphase materials wherein a different phase exists on each side of the boundary furthermore each of the constituent phases has its own distinctive physical andor chemical characteristics
Twin Boundaries
A twin boundary is a special type of grain boundary across which there is a specific mirror lattice symmetry that is atoms on one side of the boundary are located in mirror-image positions of the atoms on the other side
ATOMIC VIBRATIONS
Every atom in a solid material is vibrating very rapidly about its lattice position within the crystal In a sense these atomic vibrations may be thought of as imperfections or defects
MICROSCOPIC TECHNIQUES
Optical Microscopy
With optical microscopy the light microscope is used to study the microstructure optical and illumination systems are its basic elements
Electron Microscopy
The upper limit to the magnification possible with an optical microscope is approximately 2000 times Consequently some structural elements are too fine or small to permit observation using optical microscopy Under such circumstances the electron microscope which is capable of much higher magnifications may be employed
Grain Size Determination
The grain size is often determined when the properties of a polycrystalline material are under consideration
N the average number of grains per square inch at a magnification of 1001113090X
n represent the grain size number
Phase Boundaries
Phase boundaries exist in multiphase materials wherein a different phase exists on each side of the boundary furthermore each of the constituent phases has its own distinctive physical andor chemical characteristics
Twin Boundaries
A twin boundary is a special type of grain boundary across which there is a specific mirror lattice symmetry that is atoms on one side of the boundary are located in mirror-image positions of the atoms on the other side
ATOMIC VIBRATIONS
Every atom in a solid material is vibrating very rapidly about its lattice position within the crystal In a sense these atomic vibrations may be thought of as imperfections or defects
MICROSCOPIC TECHNIQUES
Optical Microscopy
With optical microscopy the light microscope is used to study the microstructure optical and illumination systems are its basic elements
Electron Microscopy
The upper limit to the magnification possible with an optical microscope is approximately 2000 times Consequently some structural elements are too fine or small to permit observation using optical microscopy Under such circumstances the electron microscope which is capable of much higher magnifications may be employed
Grain Size Determination
The grain size is often determined when the properties of a polycrystalline material are under consideration
N the average number of grains per square inch at a magnification of 1001113090X
n represent the grain size number
Twin Boundaries
A twin boundary is a special type of grain boundary across which there is a specific mirror lattice symmetry that is atoms on one side of the boundary are located in mirror-image positions of the atoms on the other side
ATOMIC VIBRATIONS
Every atom in a solid material is vibrating very rapidly about its lattice position within the crystal In a sense these atomic vibrations may be thought of as imperfections or defects
MICROSCOPIC TECHNIQUES
Optical Microscopy
With optical microscopy the light microscope is used to study the microstructure optical and illumination systems are its basic elements
Electron Microscopy
The upper limit to the magnification possible with an optical microscope is approximately 2000 times Consequently some structural elements are too fine or small to permit observation using optical microscopy Under such circumstances the electron microscope which is capable of much higher magnifications may be employed
Grain Size Determination
The grain size is often determined when the properties of a polycrystalline material are under consideration
N the average number of grains per square inch at a magnification of 1001113090X
n represent the grain size number
ATOMIC VIBRATIONS
Every atom in a solid material is vibrating very rapidly about its lattice position within the crystal In a sense these atomic vibrations may be thought of as imperfections or defects
MICROSCOPIC TECHNIQUES
Optical Microscopy
With optical microscopy the light microscope is used to study the microstructure optical and illumination systems are its basic elements
Electron Microscopy
The upper limit to the magnification possible with an optical microscope is approximately 2000 times Consequently some structural elements are too fine or small to permit observation using optical microscopy Under such circumstances the electron microscope which is capable of much higher magnifications may be employed
Grain Size Determination
The grain size is often determined when the properties of a polycrystalline material are under consideration
N the average number of grains per square inch at a magnification of 1001113090X
n represent the grain size number
Every atom in a solid material is vibrating very rapidly about its lattice position within the crystal In a sense these atomic vibrations may be thought of as imperfections or defects
MICROSCOPIC TECHNIQUES
Optical Microscopy
With optical microscopy the light microscope is used to study the microstructure optical and illumination systems are its basic elements
Electron Microscopy
The upper limit to the magnification possible with an optical microscope is approximately 2000 times Consequently some structural elements are too fine or small to permit observation using optical microscopy Under such circumstances the electron microscope which is capable of much higher magnifications may be employed
Grain Size Determination
The grain size is often determined when the properties of a polycrystalline material are under consideration
N the average number of grains per square inch at a magnification of 1001113090X
n represent the grain size number
MICROSCOPIC TECHNIQUES
Optical Microscopy
With optical microscopy the light microscope is used to study the microstructure optical and illumination systems are its basic elements
Electron Microscopy
The upper limit to the magnification possible with an optical microscope is approximately 2000 times Consequently some structural elements are too fine or small to permit observation using optical microscopy Under such circumstances the electron microscope which is capable of much higher magnifications may be employed
Grain Size Determination
The grain size is often determined when the properties of a polycrystalline material are under consideration
N the average number of grains per square inch at a magnification of 1001113090X
n represent the grain size number
Optical Microscopy
With optical microscopy the light microscope is used to study the microstructure optical and illumination systems are its basic elements
Electron Microscopy
The upper limit to the magnification possible with an optical microscope is approximately 2000 times Consequently some structural elements are too fine or small to permit observation using optical microscopy Under such circumstances the electron microscope which is capable of much higher magnifications may be employed
Grain Size Determination
The grain size is often determined when the properties of a polycrystalline material are under consideration
N the average number of grains per square inch at a magnification of 1001113090X
n represent the grain size number
Electron Microscopy
The upper limit to the magnification possible with an optical microscope is approximately 2000 times Consequently some structural elements are too fine or small to permit observation using optical microscopy Under such circumstances the electron microscope which is capable of much higher magnifications may be employed
Grain Size Determination
The grain size is often determined when the properties of a polycrystalline material are under consideration
N the average number of grains per square inch at a magnification of 1001113090X
n represent the grain size number
Grain Size Determination
The grain size is often determined when the properties of a polycrystalline material are under consideration
N the average number of grains per square inch at a magnification of 1001113090X
n represent the grain size number