Nonequilibrium Vacancies in Nanosystems

The influence of nonequilibrium vacancy distribution, generated by a difference of intrinsic fluxes of components under limited efficiency of vacancy sinks/sources, on various diffusion processes, is analyzed. Interdiffusion, reactive diffusion, reactive phase growth under electric current, spinodal decomposition, collapse of compound nanoshells, ripening are considered.

Low-Temperature Mechanical Alloying Of Cu-Fe and Cu-Ta Powders

ABSTRACTA model analysis is presented which explains ball-milling induced alloying in positive-heatof- mixing systems in terms of a dynamic balance between externally forced mixing and thermal phase decomposition mediated by deformation-enhanced population of defects. The possibility of eliminating the thermal decomposition to force single phase formation is examined by milling Cu- Fe and Cu-Ta powder mixtures at the liquid nitrogen temperature (LN2T). Over a range of compositions for Cu-Fe and almost the entire composition range for Cu-Ta, the two-phase region observed for room-temperature (RT) milling persisted after cryomilling. The moderate temperature dependence of milling-induced alloying is interpreted by analyzing the dynamics of the generation and annihilation of the nonequilibrium vacancies during deformation and impacts in a SPEX mill.