Effect of deformation temperature on the slip activity in pure Mg and AZX211

The microstructural evolution and slip activity in a pure Mg and AZX211 alloy during room and cryogenic temperatures (CT: −50 °C, −100 °C and −150 °C) deformation has been systematically investigated. The influence of alloying and deformation temperature on the texture, twinability and subsequently on the deformation mechanisms has been examined. Moreover, a detailed post-mortem analysis was conducted using EBSD to reveal the enabled deformation modes in 5%-strained samples at each temperature condition. The results showed that AZX211 exhibited exceptional strength/ductility synergy with 102 MPa YS, 16.4% ductility as compared to 110 MPa YS, 10.9% ductility in pure Mg at RT. Moreover, AZX211 demonstrated superior ductility as compared to pure Mg at various cryogenic temperatures. The improved performance of AZX211 was attributed to grain refinement (24.5 and 10.1 μm for pure Mg and AZX211, respectively), texture softening (20.1 mrd and 4.9 mrd for pure Mg and AZX211, respectively) and Ca-containing second phase particles dispersed in the matrix. In addition, at 5% RT and CT deformation, both the samples displayed limited twinability. To analyze the slip modes activated at a specific condition, the in-grain misorientation axes (IGMA) analysis based on the EBSD data of tensile deformed samples was carried out. Higher activities of basal <a> and prismatic <a> slip was found in AZX211, while the low deformation temperature promoted the activation of pyramidal <c+a> dislocation slip in pure Mg.