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 0.1 Ag-0.1 Ca(-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 or 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 degrees 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. (c) 2008 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.