Texture evolution and recrystallization mechanism in a Mg–3Al–1Zn alloy under ballistic impact

Abstract

The deformation microstructures near the edge of the crater of a Mg–3Al–1Zn alloy under ballistic impact with a velocity of 900 m s−1 were systematically characterized by optical microscopy (OM), scanning electron microscope (SEM), electron back-scattered diffraction (EBSD) and transmission electron microscopy (TEM) techniques. The results show that {101¯2} twinning is the predominant deformation mode, and dislocation slipping also accommodates the plastic deformation with increasing strain and stress. The texture changes from basal texture to the texture close to {101¯0} and {21¯1¯0} components as it propagates from the far matrix to the crater rim, as a result of the grain reorientation caused by twinning and dislocation slipping. The stress condition and the crystallographic orientation of grains are the main factors influencing the texture evolution. Ultrafine recrystallized grains formed in the region adjacent to the crater rim which has undergone the most severe plastic deformation. The grain fragmentation induced by twin-twin interactions, together with dislocation slipping and temperature rising during plastic deformation, results in the formation of ultrafine grains at the edge of the crater. The region near the edge of the crater shows the highest microhardness due to grain refinement hardening and strain hardening.