On the improved tensile strength and ductility of Mg--Sn--Zn--Mn alloy processed by aging prior to extrusion

This study investigated the influence of aging prior to extrusion (APE) on the tensile strength and ductility of as-extruded Mg–8.32Sn–1.85Zn–0.17Mn alloy. Results demonstrated that APE treatment dramatically increased the volume fraction of recrystallized grains, thereby decreasing the grain size of the as-extruded alloy. This phenomenon was primarily attributed to the particle-stimulated nucleation and pinning effect induced by large amounts of small Mg2Sn precipitates produced by the APE treatment and dynamic precipitation. The tensile yield strength increased from 242.4 MPa to 256.5 MPa after APE treatment. The improved tensile strength can be attributed to the enhanced grain boundary strengthening and precipitation strengthening. The ductility of the as-extruded alloy also markedly increased from 7.1% to 13.5% after the APE treatment. The improved ductility of APE alloy was attributed to the texture randomization, the activity of pyramidal slip and the suppressed formation of {10-11} contraction twins and coarse Mg2Sn phases. Keywords: Mg–Sn based alloy, Aging prior to extrusion, Microstructure, Mechanical properties