In-situ Observation of Migration of {10¯12} α Twinning in an Mg-5Gd-3.5Ga (at.%) As-Cast Alloy

We have achieved direct observation of the interaction between {10¯12}α twinning and long period stacking ordered (LPSO) structures in an Mg-5Gd-3.5Ga (at.%) as-cast alloy through in-situ compression experiments of submicron-sized pillars, and found that thick LPSO plates effectively retard the twinning propagation in the direction of perpendicular to the LPSO basal plane. In addition, although twinning can easily pass through low-density stacking faults (SFs), the step of twin boundaries on both sides of SFs on the atomic scale also exhibits resistance of SFs to twins. Dense LPSO structures hinder the occurrence of plastic deformation caused by twinning deformation. In this study, an in-situ technique was used to further discuss the strengthening mechanism of LPSO structures.