Microstructure, Mechanical and Corrosion Properties of Mg-1.61Al-1.76Ca Alloy under Different Extrusion Temperatures

Extrusion temperature can significantly influence grain size, the shape of second phase particles and the dislocation distribution of Mg alloys. In this study, the effects of extrusion temperatures ranging from 250 to 400 °C on the microstructure, mechanical properties and corrosion resistance of a Mg-Al-Ca alloy with 1.61 wt.% Al and 1.76 wt.% Ca (Mg-1.61Al-1.76Ca) were investigated. The results showed that the size of grains and phases increased with an increase in extrusion temperature; the yield strength and ultimate tensile strength values decreased with an increase in temperature, while the fracture elongation increased initially (up to 300 °C) and decreased thereafter with an increase in temperature. Under test, the extruded alloy exhibited some evidence of corrosion at 250 °C, while extrusion at 300 °C demonstrated better corrosion resistance. Thus, the 300 °C extruded alloy possessed the optimum comprehensive performance because of the relatively small grains, fine second phase particles and fewer dislocations.