Enhanced Strength–Ductility Synergy of Mg-Al-Sn-Ca Alloy via Composite Asymmetric Extrusion

Abstract

Fine-grain and weak-texture magnesium alloys are the long-term development targets of lightweight structural materials. In this study, a new composite asymmetric extrusion (CAE) is developed, which, coupling with an asymmetric die and an asymmetric billet, is proposed to improve the strength–ductility of the Mg-3.8Al-1.1Sn-0.4Ca alloy. The influence of the asymmetric billet on the microstructure and mechanical properties was investigated. The findings revealed that the asymmetric billet can induce greater plastic deformation, resulting in an increase in the cumulative strain and an improved nucleation rate. The CAE sheets exhibit fine grains (4.4 μm) and a weak tilted texture (7.57 mrd). Furthermore, the asymmetric billet results in the microstructure not forming a gradient microstructure under gradient strain along the transverse direction (TD) direction. The CAE sheets exhibited good mechanical properties, with a yield strength (YS) of 253 MPa, ultimate tensile strength (UTS) of 331 MPa, and elongation (EL) of 20%. This development shows promise in achieving high-efficiency, low-cost production of magnesium alloys.