Effect of Sr addition on the high temperature deformation behavior and processing maps of Mg-7Sn alloy

The effect of strontium (Sr) addition (1 wt%) on the hot deformation behavior of Mg-7Sn (wt%) was in-vestigated by performing high temperature compression tests in the temperature range of 300-450 degrees C and at strain rates of 0.05 s-1 - 5 s-1. The flow stress curves suggested the occurrence of dynamic re-crystallization (DRX). The constitutive equation was developed using an Arrhenius-type hyperbolic sine equation. The addition of Sr to Mg-7Sn led to a decrease in the activation energy value, suggesting easy hot working as compared to Mg-7Sn alloy. The processing maps were further generated for both alloys at 0.2 strain (strain near peak stress). For both alloys, the high-efficiency domain appeared in the high tem-perature and high strain rate ranges. However, it was observed that the safe working region increased for Sr-added Mg-7Sn compared to Mg-7Sn alloy. The deformed microstructures from the safe region characterized using electron backscatter diffraction (EBSD) showed faster development of recrystallized grain in Mg-7Sn-1Sr alloy. Further, the EBSD maps depicted the occurrence of particle stimulated nucleation (PSN) in Mg-7Sn-1Sr alloy which was absent in Mg-7Sn alloy. The PSN occurrence with the addition of Sr is predicted to cause easy deformation and increase the recrystallization fraction in the Mg-7Sn-1Sr alloy. The unstable regions showed the presence of voids in both the alloys.(c) 2023 Elsevier B.V. All rights reserved.