AMORPHIZATION AND SHEAR MICROBANDS NEAR GRAIN-BOUNDARIES IN MECHANICALLY ALLOYED METALLIC MATERIALS

A theoretical model which effectively describes a novel micromechanism of solid-state amorphization in mechanically alloyed metallic materia ls is proposed. Within the model the amorphous phase nucleates as a re sult of the intersection of a grain boundary by a plastic-shear microb and. It is shown that the growth of a nucleus of the amorphous alpha-b eta alloy near a site on a grain boundary intersected by a shear micro band is effectively controlled by the rate of diffusion mixing of atom s of the mechanically alloyed metals alpha and beta. (C) 1997 American Institute of Physics. [S1063-7842(97)00707-1].