Self-diffusion in the Laves phase was studied by using the 95Nb radio-isotope, and sputtering or mechanical sectioning. The Nb diffusivity was significantly lower than that of Co. The data for Co69Nb31 at 1143 to 1569K could be described by:

D (cm2/s) = 9.24 x 10-3 exp[-292.0(kJ/mol)/RT]

It was proposed that diffusion was mediated by thermal vacancies.

M.Denkinger, H.Mehrer: Philosophical Magazine A, 2000, 80[5], 1245-63