Microstructure and properties of hot extruded AZ31-0.25%Sb Mg-alloy

Abstract

The effects of hot extrusion treatment on the microstructure and mechanical properties of AZ31-0.25%Sb Mg alloy were investigated by means of mechanical properties measurement and microstructure observation. The results show that the microstructure of AZ31-0.25%Sb Mg alloys consists of α-Mg matrix, Mg 17Al 12 and Mg 3Sb 2 phases. The ultimate tensile strength (UTS) and yield tensile strength(YTS) of the alloy are obviously enhanced by hot extrusion treatment, and the enhanced extent of UTS and YTS increases with the decrease of hot extrusion temperature, moreover, the YTS value of the alloy at RT, after extruded at 220 °C, increases up to 131.4%, which attributes to the finer grains resulted from the dynamic recrystallization occurred during hot extrusion. As hot extrusion goes on, the slipping and concentration of dislocations continue to occur within the finer grains, which promotes the formation of the subgrains in the alloy. The deformation features of the extruded alloy during tensile deformation at RT are the twinning deformation and dislocation slipping in the twinning regions. Moreover, the deformation mechanisms of the alloy are a dislocation activation on the basal plane and a+c dislocation activation on the pyramidal planes.