Download - Thermodynamic, kinetic and phase transformation …web.access.rwth-aachen.de/THERMOCALC/proceedings/...Folie 1 Thermodynamic, kinetic and phase transformation calculations in the field

© 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 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 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



timestep 1

timestep 2


types

New nucleation


particles


from matrix

Driving force from

CALPHAD

Nucleation rate


Growth rate using

CALPHAD

Volume change

Solute removal from

matrix



© Folie 19



timestep 1

timestep 2

timestep 3



types

New nucleation


particles


from matrix

Driving force from

CALPHAD

Nucleation rate


Growth rate using

CALPHAD

Volume change

Solute removal from

matrix


© 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 23

Summary

Fields of application of thermodynamic and kinetic

simulations

Advanced modelling using CALPHAD-calculations as a

basis

Heat treatment simulation

Precipitation simulation