Current Research Progress on Wrought Magnesium-Aluminum-Calcium Based Alloys

Magnesium alloys have great potential as light-weight structural materials for weight reduction of transportation vehicles to improve their fuel efficiencies. Rapid degradation of the mechanical properties of conventional Mg-Al alloys at elevated temperatures lead to the development of high performance Mg-Al-Ca system. The edge of this alloys system over others is the low cost. Calcium is a cheap alloying element that can improve mechanical properties and ignition resistance of magnesium alloys. Post-forming process such as extrusion is more often carried out on Mg alloys at high temperatures, to further improve their properties. Microstructures of as-extruded alloys is a bimodal grain structure consisting of fine equiaxed dynamically recrystallized (DRXed) grains and elongated strips of unrecrystallized (unDRXed) areas. The high strength of extruded Mg-Al-Ca based alloys is attributed to the combined effect of fine dynamically recrystallized grains pinned with fragmented Al–Ca intermetallic compounds, nanoscale plate-like Al-Ca precipitates, spherical Al–Mn precipitates and a strong basal texture