The yield asymmetry and precipitation behavior of pre-twinned ZK60 alloy

This study aims to investigate the tension and compression properties and precipitation behavior of pre-twinned ZK60 alloys. It was found that aging treatment can effectively reduce the tension–compression yield asymmetry of pre-twinned ZK60 alloy. For the pre-twinned sample with 10 h aging treatment, the yield asymmetry ratio is nearly equal to 1. Precipitate behavior in {10–12} extension twins of ZK60 Mg alloy were characterized by TEM. Three different morphologies of precipitates, [0001] twin rods, (0001) twin plates and [11–20] twin laths were observed in {10–12} extension twins. The precipitates constituted Mg 4 Zn 7 or MgZn 2 phases. The Mg 4 Zn 7 phases have two variant orientations of the [010] zone axis, [010] Mg4Zn7 ‖ [0001] twin and (−201) Mg4Zn7 ‖ (‐12‐10) twin or (−201) Mg4Zn7 ‖ (10–10) twin , while the MgZn 2 phases have an orientation of [‐12‐10] MgZn2 ‖ [0001] twin and (10–12) MgZn2 ‖ (10–10) twin . [11–20] twin laths as a new morphology of the precipitates have been found in ZK60 alloy, which have an orientation relationship of [010] Mg4Zn7 ‖ [0001] twin and (−201) Mg4Zn7 ‖ (‐12‐10) twin . Finally, the influences of aging treatment on yield asymmetry of pre-twinned ZK60 alloy are addressed and discussed.