Primary twinning selection with respect to orientation of deformed grains in ultra-rapidly compressed AZ31 alloy

The primary twinning selection with respect to orientation of deformed grains in AZ31 alloy ultra-rapidly compressed was investigated. It was found that { 1   0   1 ¯   2 } 〈 1   0   1 ¯   1 〉 tension twinning can be activated in the grains with a wide range of orientation, whereas { 1   0   1 ¯   1 } 〈 1   0   1 ¯   2 ¯ 〉 contraction twinning in the narrow range. The tension twin variant selection is not solely of preference of Schmid factor rank. Twinning with very low Schmid factor can be activated. It was believed that critical resolved shear stress (CRSS) and strain accommodation are very important for the primary twinning and its variant selection. The much lower CRSS value of the tension twinning compared with that of the contraction twinning is responsible for its activation in wide orientation range of grains.