Precipitation-hardenable Mg–2.4Zn–0.1Ag–0.1Ca–0.16Zr (at.%) wrought magnesium alloy

A new precipitation-hardenable wrought magnesium alloy based on the Mg–Zn system with an excellent combination of high tensile yield strength, good ductility and low tensile-compression anisotropy has been developed. The Mg–2.4Zn–0.1Ag–0.1Ca(–0.16Zr) (at.%) alloys show significantly higher age-hardening responses compared to that of the binary Mg–2.4Zn alloy due to the increased number density and refinement of rod-like MgZn2 precipitates. The addition of Zr to the Mg–2.4Zn–0.1Ag–0.1Ca alloy resulted in a significant refinement of the grain size. A high number density of precipitates was observed in the Mg–2.4Zn–0.1Ag–0.1Ca–0.16Zr alloy in both the as-extruded condition and following isothermal ageing at 160 °C. The tensile yield strength of the as-extruded and aged alloys was 289 and 325 MPa, with an elongation of 17% and 14%, respectively. These alloys show relatively low compression and tensile anisotropy. The origins of these unique mechanical properties are discussed based on the detailed microstructural investigation.