Investigations on Microstructure and Mechanical Properties of Non-flammable Mg-Al-Zn-Ca-Y Alloys

Among commercial structural metals, magnesium alloys possess the lowest absolute density, featuring specific strength values superior to other structural materials such as aluminium alloys. Nevertheless, magnesium still shows some major drawbacks e.g. high oxidation tendency and more expensive processing compared to aluminium alloys. By adding calcium and yttrium to the commercially dominating AZ alloys, the oxidation behavior can be significantly improved and processing costs can be reduced. In this work, four Mg-Al-Zn-Ca-Y alloys with Al contents ranging from 3 to 9wt% were produced and compared to two standard AZ-type alloys (AZ31 and AZ91). Mechanical properties of as-extruded specimen as well as processability (casting and extrusion) and the resulting microstructures were investigated. The results show that modifying magnesium-aluminium alloys with small amounts of calcium and yttrium improves the materials' oxidation resistance and flammability behavior without deteriorating mechanical properties and processability.