Pyramidal II to basal transformation of 'c plus a' edge dislocations in Mg-Y alloys

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. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.