Hot deformation behavior and processing map of the nanocrystalline pure Mg

The thermal compression test of the nanocrystalline, as-extrusion and as-cast pure Mg was carried out by the AGX-XD universal testing machine. The results demonstrated that flow stress of pure Mg with different grain sizes decreased with increasing temperature and decreasing strain rate. Accurate prediction of the thermal deformation behavior was achieved through establishing the constitutive equations. In comparison, the nanocrystalline pure Mg represents stronger strain hardening rate and weaker sensitivity to strain rate. Based on processing map, the optimal processing area for the nanocrystalline pure Mg is at 300–400 °C, 0.01– 0.1 s −1 . The grain distribution of the nanocrystalline pure Mg remains stable and uniform after hot compression, and the grain boundary migration is the dominant deformation mechanism.