Dominant Deformation Mechanisms in Mg–Zn–Ca Alloy

The coaddition of Zn and Ca has great potential to improve the ductility of Mg alloys.Herein,the mechanical properties of an extruded Mg-Zn-Ca solid-solution alloy were studied by quasi-in situ electron backscatter diffraction(EBSD)-assisted slip trace analysis.The dominant deformation mechanisms of the Mg-Zn-Ca alloy were studied,and the origins of enhanced ductility were systematically revealed.The results indicate that most grains deformed by basal slip.In addition,multiple non-bas al slip traces were detected(particularly prismatic,pyramidal I <a>,and pyramidal I <c+a> slip traces),and their activation frequency was promoted with increasing tensile strain.The enhanced participation of non-basal slip systems is believed to play a critical role in achieving homogeneous plastic deformation,thus effectively promoting the ductility of the Mg-Zn-Ca alloy.Furthermore,first-principle calculations revealed that the coaddition of Zn and Ca significantly reduces the unstable stacking fault energy for non-basal slip,which contributes to the activation of non-basal slip systems during plastic deformation.