Pyramidal II to basal transformation of ⟨c + a⟩ edge dislocations in Mg-Y alloys

Abstract

Transitions of pyramidal ⟨c + a⟩ dislocations to sessile structures contribute to poor ductility in pure Mg. Mg-3 wt% Rare Earth (RE) alloys have good ductility, possibly due to ⟨c + a⟩ dislocation stabilization upon addition of RE solutes. Here, ⟨c + a⟩ stability is investigated in a model Mg-3 at.%Y random solid solution alloy using molecular dynamics simulations. Favorable fluctuations of Y solutes lower all dislocation energies and have no appreciable effects on the transition mechanism, energy barrier, or time. Enhanced ⟨c + a⟩ activity and improved ductility in Mg-3 wt%RE alloys are thus not likely associated with solute-stabilization of pyramidal ⟨c + a⟩ dislocations.