Study of rotational dynamic recrystallization during warm compression of an Mg-Zn-Nd-Zr alloy

Abstract

The dynamic recrystallized grains obtained by rotational dynamic recrystallization (RDRX) mechanism are finer and have fewer defects, which can effectively improve the performance of magnesium alloys. However, the impact of temperature and strain on RDRX is currently unclear. In this study, an extruded Mg-Zn-Nd-Zr alloy with trace amounts of rare earth elements and fine grain size was used as the raw material, and a warm deformation temperature interval was selected, which suppressed the large-angle migration, reduced the activity of twinning, and successfully ensured RDRX as the main recrystallization mechanism. The effects of temperature and strain on RDRX of magnesium alloys were systematically investigated, and it was found that the compression temperature and strain jointly affected the formation of RDRX. The RDRXed grains emerged during the dynamic softening stage and abundantly developed during the dynamic equilibrium stage. The percentage of the RDRXed grains increased with the increase of temperature for temperatures below 290 °C and decreased with the increase of temperature for temperatures above 290 °C at low strain levels (0.4). The percentage of RDRX monotonically increased with the increase of compression temperature at high strain (0.7). The size of the recrystallized grains increased with the increase of compression temperature. The formation of the RDRXed grains could effectively release the local strain and form a strain free region without distortion, resulting in strain softening.