Solute Softening and Vacancy Generation by Diffusion-Less Dislocation Climb in Magnesium Alloys

Abstract

Active room temperature diffusion-less climb of the edge dislocations in model Mg-Al alloys was observed using molecular dynamics simulations. Dislocations on prismatic and pyramidal I planes climb through the basal plane to overcome solute obstacles. This out-of-plane dislocation motion softens the high resistance pyramidal I glide and significantly reduces the anisotropy of dislocation mobility, and could help improve the ductility of Mg. The flow stress scales linearly with solute concentration, cAl . Dislocations climb predominantly in the negative direction, with climb angle on the order of 0.01 cAl , producing very high vacancy concentration on the order of 10-4 .