Experiments were carried out using couples between pure Zr and dilute binary alloys which contained Ag. The impurity diffusion coefficients were determined by using Darken’s relationship. That is, the interdiffusion coefficient at infinite dilution could be regarded as being the impurity diffusion coefficient of the solute. This method avoided problems, such as the surface chemical reaction of Zr specimens, which occurred during radio-tracer diffusion experiments. It was found that the present experimental results supported the occurrence of a size effect for impurity diffusion in -Zr and -Zr. The temperature ranges used here were relatively narrow (1173 to 1290K for -Zr, 1028 to 1104K for -Zr), linear Arrhenius relationships were obtained, and could be described by:
-Zr: D (m2/s) = 2.5 x 10-8exp[-128(kJ/mol)/RT]
-Zr: D (m2/s) = 1.7 x 10-6exp[-204(kJ/mol)/RT]
Y.Iijima, O.Taguchi: Journal of Materials Science Letters, 1995, 14[7], 486-9
Table 270
Bulk Diffusivity of Co in α-Zr
Temperature (K) | D (m2/s) |
859 | 3.4 x 10-12 |
773 | 1.2 x 10-13 |
726 | 1.4 x 10-14 |
686 | 1.5 x 10-15 |
666 | 5.7 x 10-16 |
641 | 1.3 x 10-16 |
610 | 1.6 x 10-17 |
579 | 1.7 x 10-18 |
516 | 7.3 x 10-21 |
473 | 7.8 x 10-23 |
449 | 4.2 x 10-24 |