The diffusion of Co was measured, by using radio-tracer techniques, at temperatures ranging from 449 to 859K (tables 175 and 176). It was found that the diffusivity in the grain boundaries was 8 orders of magnitude higher than the self-diffusivity in a-Zr. It was proposed that Co diffused interstitially in the grain boundaries, and this suggestion was supported by the small activation volume which was measured for Co grain boundary diffusion.
K.Vieregge, C.Herzig: Journal of Nuclear Materials, 1990, 175, 29-41
Table 175
Bulk Diffusivity of Co in a-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 |
Table 176
Grain Boundary Diffusivity of Co in a-Zr
Temperature (K) | D (m3/s) |
859 | 5.9 x 10-16 |
773 | 4.5 x 10-18 |
726 | 8.3 x 10-19 |
686 | 2.0 x 10-19 |
666 | 3.2 x 10-19 |
641 | 1.3 x 10-20 |
610 | 2.7 x 10-20 |
579 | 2.3 x 10-21 |
516 | 6.3 x 10-23 |
473 | 1.5 x 10-23 |
449 | 6.5 x 10-24 |