Interaction of crack with twins in hot-rolling AZ31 magnesium alloys during in-situ TEM straining experiments

In-situ straining experiments in transmission electron microscopy were performed to investigate the propagation of crack, twinning and interaction of crack with twins. Lots of micro-twins were observed in the deformation band near the tip of crack. The stress is relaxed by the formation of micro-twins and the densely developed micro-twins prevent the growth of crack from the deformation band, subsequently the cracks extend into adjacent grains across grain boundaries, and grow along cleavage plane. Multiple twins are observed in hot-rolling AZ31 magnesium alloys, when cracks propagate into twins through twin grain boundaries（GBs）, the direction of growth deviates. It is concluded that twins, especially multiple twins effectively baffle the development of crack.