Diffusion in amorphous metallic alloys – experiments, molecular-dynamics simulations, interpretation

Abstract

After a brief description of the experimental technique used in the authors' diffusion studies of metallic glasses, a representative selection of their self-diffusivity data referring to both the unrelaxed and the relaxed glassy state is presented. On the basis of these observations a model of the diffusion mechanisms operating in metallic glasses is developed and considerably refined with the aid of what has been learnt on diffusive atomic-displacement mechanisms in Fe-Zr glasses from molecular-dynamics simulations. Finally, the strength of these ideas is demonstrated by straightforwardly explaining the extraordinary diffusion-enhancement behaviour of metallic glass under light-ion bombardment and by elucidating the diffusion mechanisms in supercooled molten alloys just above the glass transition temperature.