Date post: | 17-Jan-2015 |
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Solidification of the metal
Pure metal Metal alloy
Tem
pera
ture
Time
Pouring temperature
Freezing begins
Freezing ends
•Local solidification time•Total solidification time
Time
Pouring temperature
Freezing begins
Freezing ends
Alloy formation: by solid solution
• Solvent atom (Fe)• Solute atom (c)
Alloy: steel
Substitutional solid solution Interstitial solid solution
Ex: Brass: Cu(Zn) Ex: Steel Fe (C)
Intermetallic Compound• No of atoms of constituent-elements are in specific ratio.
• Some intermetallic compounds have solid solubility
• They are strong hard and brittle.
• Bond: metallic or ionic
• Example: CuAl2 (precipitation hardening)
Two-phase alloysPhase:
Two-phase system:
• First phase is a solid solutionSecond phase particle disparsement Ex: Cu-Pb
• OR may have two sets of grains
Phase diagrams
Lever rule: to calculate the wt. fraction of solid and liquid phase
Pb-Sn binary phase diagram
Fe-C system
Cast structure of pure metal
Open and Closed Mould
Sand Casting (Expandable-mould, Permanent-pattern Casting)
Use of chaplets to avoid shifting of cores
Possible chaplet design and casting with core
Use of chills