© Folie 1
Thermodynamic, kinetic and phase transformation
calculations in the field of single crystal nickel based
superalloys
R. Rettig, M.M. Franke, R.F. Singer
Institute of Science and Technology of Metals (WTM)
Department of Materials Science and Engineering
University of Erlangen-Nürnberg
Germany
ThermoCalc User Meeting - Aachen
5th September 2013
© Folie 2
Agenda
o Nickel-based alloys as a key for energy production
o Thermodynamic and kinetic databases for alloy development
o Heat treatment modelling
o Simulation of microstructure evolution
o Summary
© Folie 3
Keppel, Alstom, Cooretec Workshop, 2006
heat recovery
steam generator gas turbine
generator
steam turbine
condensor
plant control
Siemens AG
1st stage blade
250 mm, 4,3 kg
1 MW
50 Hz
10 t
1000 °C
3 yrs
10.000,- $
Efficiency (2007): ca. 58% (330 g CO2 / kWh)
Aim 2020: ca. 63% (300 g CO2 / kWh)
Siemens AG
Combined cycle power plant
© Folie 4
Efficiency of fossile power plants
500 1000 1500 20000
20
40
60
eff
icie
nc
y i
nc
rea
se
material improvement
turbine outlet temperature is 500 °C
Carn
ot-
eff
icie
nc
y / %
process temperature / °C
data according to Siemens AG and DPG (2005)
Development of efficiency Relation of efficiency and
process temperature
efficiency increase is always
related to higher material temperatures
1965 1980 1995 2010 202520
30
40
50
60
70
brown coal
gas (CC)
planseff
icie
ncy / %
year of entry into service
© Folie 5
Harada et al. (2003) IGTC2003
temperature capability of nickel-
based superalloys
single crystalline
directionally solidified
polycrystalline
wrought alloys
Year of development
Se
rvic
e t
em
pe
ratu
re
Development of nickel-based superalloys
© Folie 6
Tc
Tg Tm
Turbine blades
1st stage, SGT5-4000F, Siemens AG polycrystalline directionally solidified single crystalline
© Folie 7
Tc
Tg Tm
Turbine blades
1st stage, SGT5-4000F, Siemens AG polycrystalline directionally solidified single crystalline
1 mm
© Folie 8
1st 2nd 3rd 4th 5th0
2
4
6
8
10
12
14
co
nte
nt
/ w
t-%
generation
Rhenium
Ruthenium
PWA1483
René N2
CMSX-2
René N5
CMSX-4
René N6
CMSX-10
Single crystal nickel-based superalloys
g‘
g
composition of single crystal superalloys
γ + γ‘-microstructure gives unique creep properties
typical alloying elements (ca. 8 – 10):
Ni-Al-Co-Cr-Mo-Re-Ru-Ta-Ti-W-B-Zr-Y
5 µm
© Folie 9
Material / process simulation at Institute WTM
thermodynamics
ThermoCalc
diffusion
DICTRA phase transformations
TC-PRISMA
microstructure
MICRESS
computer-aided alloy
development
inhouse software
(MultOPT)
process simulation
(temperature-, fluid flow)
- Flow3D
- ProCAST
- inhouse Lattice
Boltzmann code
Institute WTM /
NMF
mechanics (finite elements)
ABAQUS
© Folie 10
Agenda
o Nickel-based alloys as a key for energy production
o Thermodynamic and kinetic databases for alloy development
o Heat treatment modelling
o Simulation of microstructure evolution
o Summary
© Folie 11
Fields of application
o prediction of:
liquidus (melting) temperature
γ‘-phase fraction
γ‘-solvus temperature
TCP-phase solvus temperatures
o limitations:
„exotic“ alloying elements are not available
most commercial databases are not changable and the exact parameters are often not
accessible
calculations for untypical compositions may be critical
calculations are only valid for stable equilibrium
600 800 1000 1200 14000
20
40
60
80
100
g'
L
P
g
ph
ase
fra
cti
on
s / m
ol-
%
temperature / °C
CMSX-4, database TTNi8
© Folie 12
Verification of commercial database TTNi7
R. Rettig et al. Defect and Diffusion Forum 289 – 292 (2009) 101-108
liquidus g‘-solvus
1300 1350 1400 14501300
1350
1400
1450 with Ruwith Reno Re and Ru
Shao05
Fuchs02
Sponseller96
Copland01
Dharwadkar92
this workmelt
ing
tem
p. m
eas. / °C
melting temp. sim. / °C
800 1000 1200 1400800
1000
1200
1400
with Ruwith Reno Re and Ru
Shao05
Fuchs02
Sponseller96
Copland01
Dharwadkar92
this work
Caron00
g' s
olv
us m
eas. / °C
g' solvus sim. / °C
© Folie 13
800 900 1000 1100 1200 1300
0,1
1
10
Ta
Co Al
Ti
Cr
co
mp
osit
ion
g / a
t-%
temperature / °C
800 900 1000 1100 1200 1300
0,1
1
10Ru
Re
Mo
co
mp
osit
ion
g / a
t-%
temperature / °C
800 900 1000 1100 1200 1300
0,1
1
10
Al
Co
Ti
Cr
co
mp
osit
ion
g' / at-
%
temperature / °C
800 900 1000 1100 1200 1300
0,1
1
10
Ru
Ta
Re
Moco
mp
osit
ion
g' / at-
%
temperature / °C
good agreement bad agreement
Phase compositions calculated with TTNi7
R. Rettig et al.
Defect and
Diffusion
Forum (2009)
© Folie 14
6.5x10-4
6.7x10-4
7.0x10-4
7.2x10-4
10-14
10-13
10-12
René N5
PWA1483
NiGe1
NiGe8
dif
fusio
n c
oeff
icie
nt
D / m
²s-1
1/T / 1/K
Diffusion database development for Ni-Ge
0 2 4 6 8 10 1210
-14
10-13
10-12
10-11
1250 °C 1200 °C
1150 °C
dif
fusio
n c
oeff
icie
nt
DG
e / m
²s-1
Ge / at-%
R. Rettig et al. Journal of Phase Equilibria
and Diffusion 32 (2011) 198-205
interdiffusion
DICTRA-database from diffusion couple measurements
impurity diffusion
6.5x10-4
6.7x10-4
7.0x10-4
7.2x10-4
10-14
10-13
10-12
self diffusion
Rettig et al. (2011)
Hirano et al. (1962)
Mantl et al. (1983)
Ge impurity
dif
fusio
n c
oeff
icie
nt
D / m
²s-1
1/T / 1/K
© Folie 15
Agenda
o Nickel-based alloys as a key for energy production
o Thermodynamic and kinetic databases for alloy development
o Heat treatment modelling
o Simulation of microstructure evolution
o Summary
© Folie 16
Agenda
o Nickel-based alloys as a key for energy production
oThermodynamic and kinetic databases for alloy development
o Heat treatment modelling
o Simulation of microstructure evolution
o Summary
© Folie 17
A multicomponent, multiphase precipitation model
Idea of model Loop for all timesteps
timestep 1
Loop for all precipitate
types
New nucleation
Growth of all existing
particles
Total removal of solute
from matrix
Driving force from
CALPHAD
Nucleation rate
Loop for all particles
Growth rate using
CALPHAD
Volume change
Solute removal from
matrix
numerical Kampmann-Wagner model (1984), T. Sourmail (2002)
red: new multicomponent model
© Folie 18
A multicomponent, multiphase precipitation model
Idea of model Loop for all timesteps
timestep 1
timestep 2
Loop for all precipitate
types
New nucleation
Growth of all existing
particles
Total removal of solute
from matrix
Driving force from
CALPHAD
Nucleation rate
Loop for all particles
Growth rate using
CALPHAD
Volume change
Solute removal from
matrix
numerical Kampmann-Wagner model (1984), T. Sourmail (2002)
red: new multicomponent model
© Folie 19
A multicomponent, multiphase precipitation model
Idea of model Loop for all timesteps
timestep 1
timestep 2
timestep 3
numerical Kampmann-Wagner model (1984), T. Sourmail (2002)
Loop for all precipitate
types
New nucleation
Growth of all existing
particles
Total removal of solute
from matrix
Driving force from
CALPHAD
Nucleation rate
Loop for all particles
Growth rate using
CALPHAD
Volume change
Solute removal from
matrix
red: new multicomponent model
© Folie 20
Modelling of TCP-phase precipitation
1 10 100 1000 10000900
1000
1100
12002.5 % Ru
0 % Ru
1 vol-% Ptem
pe
ratu
re /
°C
time / h
multicomponent Kampmann-Wagner-
model (coupled to ThermoCalc and
DICTRA)
databases: TTNi8 + MobNi1
experimental data: Sato et al. (2006) Scripta Mat
9 x 7 x 6 μm3
experimental 3rd generation alloy
ASTRA1-20
K. Matuszewski, R. Rettig et al.
Advanced Engineering Materials (2013)
FIB-tomography
© Folie 21
the large difference in the driving force in both alloys is the reason for the very different
precipitate lengths
101
102
103
104
105
0
50
100
150
200
equilibrium
experiment [Vol06]
simulation
EROS4
IN792Re
pre
cip
itate
len
gth
/ µ
m
time / h
Modelling of TCP-phase precipitation
Driving force influences precipitate length
600 800 1000 12000
2
4
6
8
10
850 °C
IN792Re
EROS4
dri
vin
g f
orc
e / k
J m
ol-1
temperature / °C
precipitate length driving force for precipitation
Rettig et al. Acta Materialia 59 (2011) 317-327
© Folie 22
Agenda
o Nickel-based alloys as a key for energy production
o Thermodynamic and kinetic databases for alloy development
o Heat treatment modelling
o Simulation of microstructure evolution
o Summary
© Folie 23
Summary
Fields of application of thermodynamic and kinetic
simulations
Advanced modelling using CALPHAD-calculations as a
basis
Heat treatment simulation
Precipitation simulation