{101¯2}−{101¯2} double tensile twinning in a Mg-3Al-1Zn alloy sheet during cyclic deformation

The typical fracture morphology of the Mg-3Al-1Zn alloy after cyclic deformation was investigated using optical microscopy (OM), and an electron back-scatter diffraction (EBSD). A novel finding of this study is that large number of stripe-like laminas were found within the primary {101¯2} tensile twins in the crack initiation and crack propagation regions. It is shown that these laminas primarily result from {101¯2}−{101¯2} twinning during cyclic deformation. According to the results and combined with theoretical analysis, the formation of {101¯2}−{101¯2} twins are largely contributing to the local strain accommodation caused by different twin variants.