The effect of solute cloud formation on the second order pyramidal to basal transition of ⟨c plus a⟩ edge dislocations in Mg-Y solid solutions

We study the effect of solute segregation on pyramidal to basal transformation of < c + a > edge dislocations in a model Mg-Y alloy, using a hybrid Monte Carlo/Molecular Dynamics method. While a random solute distribution has no appreciable effect on this undesirable transition, a solute cloud around the dislocation slows and effectively prevents it in case of Mg-3 at % Y alloy. Comparing with the time scale required for diffusion of Y to the dislocation, suggests that segregation of Y and other fast diffusing elements can be engineered to prohibit this glissile to sessile transition, and stabilize the pyramidal glide of < c + a > dislocations. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.