DICTRA Work in the SFB 370

Turbine Blade Process Chain

Turbine Blade Process Chain

Casting Heat Treatment Coating Testing

Team:

The Turbine Blade

Composition of the used superalloy CMSX-4 (wt.%)

Structure of superalloy after solidification

Bal0.60.126.41.06.52.96.59.65.61

NiMoHfWTiTaReCrCoAl

Reactions during solidification:

liquid

liquid

γ (fcc)

γ (fcc) γ‘ (fcc, ordered)

γ‘ (fcc, ordered)γ (fcc)

+

Primary Solidification

Transverse section of a quenched sample, EDX line scans indicated*

* Dexin Ma, Uwe Grafe, Materials Science and Engineering A270 (1999) 339-342

0 20 40 60 80 100 120 140 1600

2

4

6

8

10

12

Ta

Cs (

wt.-

%)

L (µm)0 20 40 60 80 100 120 140 160

0

2

4

6

8

10

12

Ti

Cr

Al

Cs (

wt.-

%)

L (µm)0 20 40 60 80 100 120 140 160

0

1

2

3

4

5

6

7

8

9

10

11

12

Re

W

Co

Cs (

wt.-

%)

L (µm)

γ

liquid

ckγ

ckl

vα DICTRA cell

Secondary Solidification

γ

liquid

ckγ

ckl

Equilibrium calculation agrees well with material dataScheil simulation differs significantly from diffusion calculation

1540 1560 1580 1600 1620 1640 16600.0

0.2

0.4

0.6

0.8

1.01540 1560 1580 1600 1620 1640 1660

Frac

tion

solid

Temperature (K)

DICTRA Equilibrium Gulliver-Scheil

γ‘

1598±3 K

1657 K

Solid State Transformation

γ

ckγ

γ‘

γ‘

0 20 40 60 80 100 120 140 1600.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

800 K

1400 K

1500 K

1550 K

Mol

e fra

ctio

n γ'

Distance (µm)

Interdendritic γ‘ is neglectedAmount of γ‘ correlates with microsegregations

Summary

• Diffusion simulations significantly improve the prediction of fractionsolid compared to the Scheil Model

• Calculated microsegregations agree well with experiments• Dependence of dispersed γ‘ on microsegregations can be shown

with DICTRA

DICTRA simulations are a valuable tool to simulate the microstructure of CMSX-4