Effect of Hot Extrusion and Annealing on Microstructure and Properties of Mg-Zr-(Ca/Y) Alloys

The influence of hot extruding and annealing on the microstructure and properties of three Mg-Zr alloys were investigated.The results showed that significant grain refinement during hot extrusion improved the mechanical property of the alloy.In cast condition,damping capacity increased with higher strain amplitude.However,upon hot extrusion,the damping capacity of the alloys is lowered remarkably,weakly depended on strain amplitude.Annealing of the hot extruded alloy resulted in damping capacity increase,but it was still lower than the as-cast alloy.The mechanical properties of Mg-0.6Zr-0.3Ca and Mg-0.6Zr-0.3Ca-0.1Y alloys were higher than that of Mg-0.6Zr alloy in different conditions,and their damping capacities were similar to that of Mg-0.6Zr alloy in cast condition,yet much lower after hot extrusion and annealing.The change of damping capacities of three alloys at different processing conditions could be explained by the dislocation model of Granato and Lucke.