DIFFUSION IN AMORPHOUS METALLIC ALLOYS

A representative selection of experimental data as well as molecular-d ynamics simulations serve as a basis for elucidating the atomic mechan isms of self-diffusion in amorphous and nanocrystalline metallic alloy s. In particular, it is concluded that in as-produced amorphous alloys self-diffusion occurs indirectly via quasi-vacancies. whereas in rela xed amorphous alloys self-diffusion is controlled by direct collective mechanisms, among which thermally activated displacement chains play a major role. These mechanisms are contrasted with those governing tra nsition metal diffusion in amorphous silicon.