Effect of Trace Additions of Sn and Mn on the Hot Deformation Behavior of Mg–2Al–Zn Alloy Under a High Strain Rate

Abstract

The effect of trace addition of Sn (1 wt.%) and Mn (0.5 wt.%) on the hot deformation behavior of extruded Mg–2Al–Zn (AZ21) alloy at a high strain rate (10 s⁻¹) was investigated through thermal simulation experiments. The addition of Sn and Mn resulted in a decrease in the peak stress of the AZ21 alloy. Furthermore, the dynamic recrystallization (DRX) process of the AZ21 alloy was accelerated, and the volume fraction of twins decreased. The twin variant selection mechanism followed either the Schmid factor (SF) or geometrical compatibility factor criterion. The addition of Sn and Mn accelerated DRX in AZ21 alloy through three mechanisms observed during deformation: continuous DRX (CDRX), discontinuous DRX (DDRX), and twin-induced recrystallization (TDRX). After adding Sn and Mn, the DRX mechanisms in the Mg–2Al–Zn–Sn–0.5Mn (AZTM2110) alloy were limited to CDRX and DDRX, with TDRX disappearing. This was attributed to fine original grain size, which reduced the number of twins and significantly increased the twin thickness-to-length ratio, thus preventing TDRX.