Change of the self-diffusion of exp 58 Co in Co sub 79 Nb sub 14 B sub 7 during transition from the amorphous to the nanocrystalline phase

Starting out from the relaxed amorphous phase, Co sub 79 Nb sub 14 B sub 7 was exposed to thermal annealing treatments by which specimens of different degree of nanocrystallization have been produced. These were used for investigations of the self-diffusivity of exp 58 Co radio/tracer atoms in dependence of the microstructure and the diffusion temperature. The results are interpreted in terms of direct collective diffusion which is restricted to the amorphous regions of the specimens and becomes trap-retarded when crystallization proceeds.