Diffusion couples of Ni and Re were vacuum-annealed at temperatures of between 1263 and 1383K, for times of between 50 and 228h. The solubility limit of Ni in Re was found to be about 25at%. This value was significantly higher than the calculated values, but was lower than some published data. The high solubility and the large measured diffusion depth of Ni in Re showed that the latter could not be used as an effective diffusion barrier for W fibers in Ni-based metal-matrix composites. The diffusion profiles of Ni in Re indicated that the chemical diffusion coefficient was concentration-dependent (table 207). The activation energy for the interdiffusion of Ni into Re (table 208) was significantly lower than the self-diffusion parameters. It was suggested that Ni diffused into Re along grain boundaries; as observed for the diffusion of Ni into W.

C.M.Neubauer, D.Mari, D.C.Dunand: Scripta Metallurgica et Materialia, 1994, 31[1], 99-104

 

Table 206

Intrinsic Diffusion of Pd in Ni-Pd at 1100C

 

Ni (at%)

Couple

D (m2/s)

6.6*

multi-foil

3.3 x 10-15

13*

multi-foil

9.7 x 10-15

17.6

incremental

2.0 x 10-14

25*

multi-foil

2.34 x 10-14

37*

multi-foil

3.85 x 10-14

40.3

incremental

6.5 x 10-14

48*

multi-foil

4.97 x 10-14

51.6

incremental

4.7 x 10-14

58*

multi-foil

4.51 x 10-14

58.5

incremental

4.3 x 10-14

68*

multi-foil

3.11 x 10-14

77*

multi-foil

2.08 x 10-14

82.6

incremental

8.1 x 10-15

85*

multi-foil

1.19 x 10-14

92*

multi-foil

6.4 x 10-15

* concentration at the Kirkendall plane