Diffusion coefficient matrices were determined (tables 74 to 77) for 31 points in the α/δ phase field of the ternary phase diagram at 900C, by using diffusion couples and electron probe microanalysis. The matrices were checked for consistency by applying the Onsager and Kirkaldy relationships. It was found that the consistency was good in the center of the ternary phase field, but that there were significant deviations at the phase boundaries. The deviations were attributed to the existence of systematic uncertainties in the analyses. The results indicated that the value of DCrCrFe fell quickly with increasing Cr concentration, when the fraction of Al was greater than 0.2, but it was not a sensitive function of the Al concentration. Similarly, DAlAlFe was not a sensitive function of the Al concentration, and decreased with increasing Cr content.

H.C.Akuezue, J.Stringer: Metallurgical Transactions, 1989, 20A[11], 2767-81

 

Table 74

Diffusion Coefficient, DAlAlFe, for the Fe-Cr-Al System

 

Al (at%)

Cr (at%)

Value (cm2/s)

11.34

40.16

3.3 x 10-11

11.43

39.56

1.5 x 10-11

11.88

36.72

3.5 x 10-11

14.72

23.58

1.12 x 10-10

14.95

22.75

1.80 x 10-10

15.96

19.07

1.70 x 10-10

16.17

18.32

3.26 x 10-10

17.56

13.50

1.93 x 10-10

18.67

9.21

3.26 x 10-10

18.75

8.90

3.73 x 10-10

22.07

17.38

1.74 x 10-10

22.77

21.15

1.41 x 10-10

24.12

11.96

2.92 x 10-10

24.83

16.49

2.82 x 10-10

27.34

10.83

2.81 x 10-10

28.40

6.56

5.50 x 10-10

29.59

17.19

l.38 x 10-10

continued

Table 74 (continued)

Diffusion Coefficient, DAlAlFe, for the Fe-Cr-Al System

 

Al (at%)

Cr (at%)

Value (cm2/s)

29.59

17.19

l.38 x 10-10

33.55

10.70

8.3 x 10-11

34.53

3.63

4.56 x 10-10

38.03

5.02

1.31 x 10-10

39.20

1.27

3.80 x 10-10

39.25

1.33

2.33 x 10-10

39.54

8.22

8.3 x 10-11

39.68

6.02

6.9 x 10-11

39.79

3.10

2.34 x 10-10

39.80

3.14

2.02 x 10-10

39.84

4.37

1.83 x 10-10

45.66

4.09

-2.6 x 10-11

45.87

3.47

-1.9 x 10-11

46.17

2.51

-1.0 x 10-11

46.33

1.89

6.0 x 10-12