Self-diffusion in the Laves phase was studied by using the 57Co radiotracer, and sputtering or mechanical sectioning. It was found that all of the activation enthalpies were of similar magnitude. The data could be described by:

Co69Nb31 (1143-1523K):     D (cm2/s) = 2.84 x 10-1 exp[-294.7(kJ/mol)/RT]

Co71Nb29 (1141-1423K):     D (cm2/s) = 3.32 x 100 exp[-279.5(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