Effects of cerium on microstructures, recovery behavior and mechanical properties of backward extruded Mg-0.5Mn alloys

Mg-0.5Mn-xCe (x=0, 0.5, 1 and 1.5, wt%) alloys have been prepared by zone purifying method followed by backward extrusion technique. The microstructures, recovery behavior from 150 to 330 °C and mechanical properties of Mg-0.5Mn-xCe alloys were investigated. The results revealed that the grain size of Mg-0.5Mn-xCe alloys was reduced with the increased concentration of Ce. The backward extruded Mg-0.5Mn-1.5Ce alloy was mostly composed of Mg12Ce, Mg17Ce2 and Mg matrix. The addition of a small amount of Ce accelerated the recovery. The recovery temperature was decreased as the addition of Ce was increased. In addition, the grain growth at elevated temperatures was impeded owing to the existence of fine secondary precipitates near to grain boundaries. Both strength and ductility were greatly improved by micro-alloying with Ce, which is mostly related to the fine grain size and homogeneous secondary precipitate.