{101‾2} detwinning in magnesium alloys - A review

For Mg alloys containing pre-strained twins, detwinning is dominant under specific loading conditions including strain-path changed reloading, cyclic loading, and unloading. Detwinning chiefly occurs via reverse twin boundary migration or secondary twin nucleation, the choice of which is the result of pinned boundaries. Increasing evidence has demonstrated that detwinning exerts complex effects on the strength, ductility and fatigue properties of Mg alloys. Those effects mainly depend on crystallographic orientation, alloy composition, detwinning degree, twin volume fraction, loading conditions and twin-defect interactions. In recent years, as Mg alloy components in aerospace and other fields often serve under complex multiaxial loads and extreme conditions, the detwinning behavior under these conditions directly affects the service safety. The activation mechanisms, influencing factors, and the responses of microstructure and properties to detwinning become more complex. This study offers a thorough overview of key findings upon detwinning mechanisms, key characteristics, influencing factors, experimental methods as well as modeling approaches, and the responses of microstructure and properties to detwinning. The aim is to reveal detwinning mechanisms under complex conditions and offer guidelines for the establishment of multi-scale regulation models in pre-twinned Mg alloys. The results of this work could provide theoretical support for the design and application of high-performance Mg alloys.