The diffusion of Co was measured, by using radio-tracer techniques, at temperatures ranging from 449 to 859K (tables 333 and 334). It was found that the diffusivity in the grain boundaries was 8 orders of magnitude higher than the self-diffusivity in α-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