Revealing microstructures evolution and dynamic recrystallization mechanisms of Mg–Sn–Mn alloy during compressive deformation at elevated temperature

Abstract

The flow behavior of as-extruded Mg–3Sn-1.5Mn (wt.%) alloy was systematically researched via isothermal compression tests. The compressive temperatures (T) were from 250 °C to 400 °C, the strain rates were from 0.001 s−1 to 1s−1 and the true strain reached 0.69. Based on compression curves, flow stress apparently rose with increasing strain rate and/or decreasing temperature. Combined with the analysis of microstructure and processing map, the optimum working parameter was determined in the range of 350–400 °C, 0.01–1 s−1. According to electron backscatter diffraction (EBSD) analysis results, texture intensity significantly decreased and the basal (0001)//ED texture had transformed to basal <0001>//CD texture after compressive deformation obviously. Furthermore, the typical discontinue dynamic recrystallization (DDRX) and continue dynamic recrystallization (CDRX) were largely believed to be the major DRX mechanisms in Mg–3Sn-1.5Mn alloy. Both increasing temperature and decreasing strain rate had obvious influence on the degree of DRX. The activated slip systems in deformed grains were determined by the analysis of the in-grain misorientation axis (IGMA). As deformation temperature elevated, pyramidal <c+a> slip greatly activated and dominated compressive deformation.