Predicting the formation of <c + a> dislocations in magnesium alloys from multiple stacking fault energies

The presence of alloying elements in magnesium (Mg) can activate pyramidal <c + a> slip systems and thereby improve the plasticity of Mg at room temperature. In this study, we predict the effect of alloying elements on the formation of <c + a> dislocations based on a synergistic effect stemming from both leading and trailing partial dislocations. Our calculations demonstrate that the addition of rare earths, Li, Ca, and Sn significantly lowers at least one energy barrier in pure Mg, and ultimately promotes the formation of the pyramidal I and/or pyramidal II slip systems. The reduced energy barriers are mainly attributed to the local lattice distortions and charge redistribution induced by alloying atoms. These findings provide important insight into the influence of alloying on the formation of <c + a> dislocations, and may ultimately facilitate the development of a framework to design high-plasticity Mg alloys.