First-principles study of the generalized stacking fault energy in Mg–3Al–3Sn alloy

Generalized stacking fault energies of magnesium without and with Al and Sn dopings were studied using first-principles calculations to investigate mechanisms of improved ductility for a new Mg–3Al–3Sn alloy. Reduced unstable stacking fault energy (γus  ) results in the improved activity of {0001}〈112¯0〉 and the activation of the {101¯1}〈112¯0〉 and {112¯2}〈112¯3〉 slip systems. Moreover, the lower γus   of {101¯1}〈112¯0〉 than of {101¯0}〈112¯0〉 leads to the replacement of the latter by the former to be the second primary slip system.