Mechanical properties of naturally aged Mg-Zn-Cu-Mn alloy

The Mg-Zn-based alloys exhibit a remarkable response to ageing at reduced temperatures including ambient temperature. A favorable combination of a very high ductility, appreciably high yield strength and hardness almost equal to that in the T6 condition, can be achieved in the naturally aged cast Mg-Zn-Cu-Mn alloy. The strengthening is produced by a dense dispersion of fine coherent and semi-coherent precipitates and the deformation most likely involves basal and prismatic slip to a greater degree than twinning, which is more pronounced in the T6 condition. When ageing is conducted at an intermediate temperature, further significant hardening beyond that in the T4 and T6 conditions is achieved due to the formation of a high number density of four different types of precipitates.