The Ce-Nd diffusion couples were annealed at 425, 550, and 650C. Both intrinsic and interdiffusion data were obtained, as well as the activation energy as a function of composition. On the basis of an analysis of the results (tables 66 and 67), it was deduced that Ce-Nd interdiffusion increased in the -Ce phase and decreased in the -Ce plus -Nd phase, with increasing Nd concentration. The activation energy for Ce-Nd interdiffusion in the -Ce plus -Nd phase was about 150kJ/mol. The activation energy in the -Ce phase was lower, and changed with concentration. Interdiffusion was generally higher in the -Ce phase. The Ce intrinsic diffusivity was higher than that of Nd, and the ratio of the Ce intrinsic diffusivity to that of Nd increased with increasing temperature. Consequently, the Kirkendall plane shifted to the Ce side of diffusion couples. On the basis of discontinuities in the concentration profiles in these couples, it was suggested that the -Ce plus (-Ce, -Nd) 2-phase region of the Ce-Nd phase diagram should be shifted more towards the Nd side of the diagram.
D.D.Keiser: Scripta Metallurgica et Materialia, 1995, 33[6], 959-65
Table 66
Interdiffusion Coefficients for Ce-Nd Alloys
Nd (at%) | Temperature (C) | D (cm2/s) |
0.10 | 425 | 2.1 x 10-12 |
0.10 | 550 | 3.5 x 10-11 |
0.10 | 650 | 1.4 x 10-10 |
0.15 | 425 | 5.4 x 10-12 |
continued
Table 66 (continued)
Interdiffusion Coefficients for Ce-Nd Alloys
Nd (at%) | Temperature (C) | D (cm2/s) |
0.15 | 550 | 4.7 x 10-11 |
0.15 | 650 | 1.5 x 10-10 |
0.20 | 425 | 2.4 x 10-12 |
0.20 | 550 | 6.0 x 10-11 |
0.20 | 650 | 1.9 x 10-10 |
0.60 | 425 | 3.4 x 10-13 |
0.60 | 550 | 6.5 x 10-11 |
0.60 | 650 | 1.4 x 10-10 |
0.65 | 425 | 2.4 x 10-13 |
0.65 | 550 | 4.7 x 10-11 |
0.65 | 650 | 9.7 x 10-11 |
0.70 | 425 | 1.7 x 10-13 |
0.70 | 550 | 3.4 x 10-11 |
0.70 | 650 | 7.9 x 10-11 |
Table 67
Activation Energies for Interdiffusion
in Ce-Nd Alloys at 425 to 650C
Nd (at%) | Q (kJ/mol) |
0.10 | 100.6 |
0.15 | 79.8 |
0.20 | 105.6 |
0.60 | 148.0 |
0.65 | 147.5 |
0.70 | 149.6 |