A study was made of the damping of a 2-phase material which exhibited a rapid decrease in elastic modulus, together with an increase of ductility, at temperatures above 870K. It was found that the general features of the high-temperature damping spectra (a relaxation peak superposed on a low-frequency background) were essentially the same for the alloy and for its component phases ( and ). It was concluded that the ductility and modulus drop were related to the presence of the relaxation peak in the alloy. In the phase, this relaxation peak was attributed to Ni (and Co) diffusion with the Arrhenius parameters: 5 x 10-16s and 2.6eV. In the phase, the peak had the same origin but its characteristics changed during thermal cycling because of the dissolution of ' precipitates.
P.Gadaud, A.Rivière, J.Woirgard: Materials Science Forum, 1993, 119-121, 401-6
Table 177
Interdiffusion Coefficients for the Ni-Cr-Co-Mo System at 1300C
Cr(at%) | Co(at%) | Mo(at%) | Coefficient | D (cm2/s) |
3.2 | 47.9 | 7.7 | DCrCrNi | 6.8 x 10-10 |
6.4 | 27.1 | 7.7 | DCrCrNi | 6.4 x 10-10 |
6.5 | 23.9 | 7.6 | DNiCrCo | -1.7 x 10-10 |
10.8 | 26.2 | 7.4 | DCrCrNi | 6.9 x 10-10 |
15.2 | 25.8 | 7.4 | DCrCrNi | 8.2 x 10-10 |
18.4 | 25.6 | 7.2 | DCrCrNi | 1.0 x 10-9 |
20.8 | 25.0 | 7.4 | DCrCrNi | 9.9 x 10-10 |
22.2 | 3.7 | 6.2 | DNiCrCo | -2.0 x 10-10 |
22.7 | 24.5 | 7.4 | DCrCrNi | 9.7 x 10-10 |
24.2 | 24.1 | 7.4 | DCrCrNi | 7.5 x 10-10 |
25.8 | 19.8 | 7.1 | DCoCoNi | 3.7 x 10-10 |
25.8 | 21.4 | 7.1 | DCoCoNi | 4.2 x 10-10 |
25.9 | 16.2 | 7.1 | DCoCoNi | 3.3 x 10-10 |
26.3 | 7.4 | 6.6 | DCoCoNi | 4.8 x 10-10 |
26.5 | 4.4 | 6.4 | DCoCoNi | 6.0 x 10-10 |
26.8 | 1.7 | 6.6 | DCoCoNi | 8.9 x 10-10 |