Origin of profuse {11[formula omitted]1} deformation twins in Mg-Gd alloys

Abstract

Deformation twins in Mg–Gd alloys are investigated. It is found that the dominant twinning mode switches from {101¯2} twinning to {112¯1} twinning, with an increase in the Gd concentration in Mg. Our first-principles calculations suggest that the formation of the {112¯1} twin in the Gd-rich alloy is triggered by the reduced {112¯1} twin boundary energy, which results from strain relaxation along the twin boundary. Furthermore, this twinning mode is suggestive to be activated in other Mg alloys with a high concentration of solute atoms having larger size than Mg.