Detwinning behavior of Mg-3Al-1Zn alloy at elevated temperatures

Detwinning behavior of a strongly textured magnesium alloy AZ31 at different temperatures was investigated, with a focus on the effect of temperature on twin boundaries (TBs) migration. A hot extruded Mg alloy AZ31 rod was subjected to a 3% pre-compression along the extrusion direction (ED) to generate {101¯2} twins. Subsequent tensions along the ED at temperatures of 30 °C, 100 °C, 150 °C, 200 °C and 250 °C, respectively, were carried out to initiate detwinning. Mechanical behavior and microstructure evolution during detwinning deformation were examined. Our results show that the activation stress for {101¯2} TBs migration decreases with the increasing of temperature from 30 °C to 250 °C. Even at 250 °C, detwinning rather than non-basal slips dominates tension along the ED of pre-strained specimens. All strain hardening curves of detwinning deformation at temperatures of 30-250 °C contain three stages that often appear in a {101¯2} twinning predominant deformation. The length of Stage II is predominantly related to {101¯2} twin volume fraction. It is found that the peak hardening rate in Stage II decreases with increased temperature.