Interdiffusion was investigated, using solid/solid diffusion couples, in the α (face-centered cubic) region of the quaternary Ni-Cr-Co-Mo system at 1300C in order to determine the diffusion paths and diffusional interactions between the components. It was found that the concentration profiles for a given couple exhibited a common cross-over composition which related the relative depths of diffusion in the terminal alloys. The interdiffusion fluxes were calculated directly from the concentration profiles, and the quaternary interdiffusion coefficients were calculated at selected compositions (table 177). It was discovered that Ni and Co exhibited up-hill diffusion against their individual concentration gradients, in a direction which was opposite to the interdiffusion of Cr. The quaternary diffusion paths were described, by a set of partial diffusion paths, on the basis of relative concentration variables.
J.A.Heaney, M.A.Dayananda: Metallurgical Transactions A, 1986, 17[6], 983-90
Table 178
Diffusivity of Cr in Ni-Cr-Fe Alloys
Cr(wt%) | Fe(wt%) | Temperature (K) | D (cm2/s) |
0 | 23.8 | 1336 | 3.13 x 10-11 |
0 | 23.8 | 1536 | 8.11 x 10-10 |
0 | 53.4 | 1336 | 2.35 x 10-11 |
0 | 53.4 | 1536 | 6.15 x 10-10 |
9.9 | 35.0 | 1336 | 2.29 x 10-11 |
9.9 | 35.0 | 1536 | 8.01 x 10-10 |
10.1 | 11.2 | 1336 | 2.80 x 10-11 |
10.1 | 11.2 | 1536 | 7.12 x 10-10 |
10.1 | 25.3 | 1336 | 2.52 x 10-11 |
10.1 | 25.3 | 1536 | 7.01 x 10-10 |
10.1 | 54.9 | 1336 | 1.68 x 10-11 |
10.1 | 54.9 | 1536 | 6.20 x 10-10 |
19.1 | 61.8 | 1336 | 1.26 x 10-11 |
19.1 | 61.8 | 1536 | 3.26 x 10-10 |
19.6 | 37.4 | 1336 | 1.61 x 10-11 |
19.6 | 37.4 | 1536 | 5.36 x 10-10 |
19.9 | 25.0 | 1336 | 1.18 x 10-11 |
19.9 | 25.0 | 1536 | 3.86 x 10-10 |
20.0 | 16.5 | 1336 | 2.15 x 10-11 |
20.0 | 16.5 | 1536 | 6.86 x 10-10 |
20.0 | 45.1 | 1336 | 1.70 x 10-11 |
20.0 | 45.1 | 1536 | 4.59 x 10-10 |
21.5 | 0 | 1336 | 1.72 x 10-11 |
21.5 | 0 | 1536 | 5.91 x 10-10 |
30.4 | 4.3 | 1336 | 2.53 x 10-11 |
30.4 | 4.3 | 1536 | 6.50 x 10-10 |
30.4 | 14.8 | 1336 | 2.05 x 10-11 |
30.4 | 14.8 | 1536 | 5.49 x 10-10 |
30.4 | 34.8 | 1336 | 1.47 x 10-11 |
30.4 | 34.8 | 1536 | 5.19 x 10-10 |
Table 179
Bulk Diffusivity of 51Cr in Ni-15.18Cr-7.76Fe-0.07wt%C
Temperature (K) | D (m2/s) |
1424 | 2.0 x 10-14 |
1346 | 1.1 x 10-15 |
1303 | 2.8 x 10-16 |
1223 | 5.1 x 10-17 |
1173 | 1.2 x 10-17 |
1113 | 2.7 x 10-18 |
1073 | 5.1 x 10-19 |
973 | 1.3 x 10-20 |
894 | 1.8 x 10-22 |