Anomalous Strain Rate Sensitivity of $\{ 10\overline{1}2\}$ $\langle 10\overline{1}\overline{1}\rangle$ Twinning in a Magnesium Alloy at High Temperature

Abstract

Anomalous strain rate sensitivity of $\{ 10\overline{1} 2\}$ $\langle 10\overline{1}\overline{1}\rangle$ twinning was observed in a Mg-Al-Mn magnesium alloy during extrusion around 723 K (450 °C). The density of $\{ 10\overline{1}2\}$ $\langle 10\overline{1}\overline{1}\rangle$ twins decreases as the ram speed increases. At 10 mm min⁻¹, relatively high density twins are activated, but much fewer twins were observed at 30 mm min⁻¹; at 50 mm min⁻¹, twins were hardly seen. The negative strain rate sensitivity was ascribed to the interaction of $\{ 10\overline{1}2\}$ $\langle 10\overline{1}\overline{1}\rangle$ twinning with defects.