A novel strategy to achieve uniform ultrafine grains in Mg-Al-Sn-Ca alloy via pre-twinning combined with differential-thermal asymmetric extrusion

Abstract

Obtaining fine grains with weak textures is an efficacious way of simultaneously improving the strength and ductility of magnesium (Mg) alloys. In this paper, an Mg-Al-Sn-Ca alloy with uniformly ultrafine grains and a weak texture has been prepared via pre-twinning followed by differential-thermal asymmetric extrusion (DAE). The alloy exhibits good strength and ductility (ultimate tensile strength: ∼381 MPa; elongation: ∼22 %). The results show that {102} tensile twins significantly promote dynamic recrystallization (DRX) during DAE, which beneficial for the formation of uniform fine grain structure and weak bimodal texture. This research provides valuable insights and methods for tailoring excellent mechanical properties of Mg alloys, facilitating their practical application in various engineering scenarios.