Achieving excellent ductility with increased Schmid Factor but decreased direct strain contribution of basal slip in an intergranular misorientation tailored magnesium alloy

Weakening the basal texture was a commonly used method to improve the ductility and formability of magnesium alloys. The easier activation of basal slip was often considered to be an important reason for the improved ductility of the weak basal textured magnesium alloys. However, basal slip alone cannot well satisfy the Von Mises criterion and its activation was nearly saturated in strong basal textured magnesium alloys. The deformation mechanisms of weak basal textured magnesium alloys are still open to debate. In this work, the Schmid Factor (SF) of the basal slip is obviously increased and a high fracture elongation of ∼35 % is achieved in AZ31 alloy by careful tailoring of grain orientation and rational selection of loading direction. Grain size scale strain distribution by high-resolution digital image correlation (DIC) and slip activation based on the slip trace method were used to in-depth analyze the deformation mechanisms. Although the basal slip’ average SF increases, the strain statistics show that the direct strain contribution of the basal slip to the deformation gets decrease, contrary to conventional expectation. This is mainly attributed to the coupling effect of the increased basal slip’ SF with the large intergranular misorientation, which significantly promotes the activation of non-basal slip and increases its contribution to the deformation, thus leading to a lower direct strain contribution of the basal slip. The results of the study may help to further reveal the plastic deformation mechanism of magnesium alloys and improve the plasticity of magnesium alloys.