Effects of thermomechanical treatments on microstructure and mechanical properties of AZ80 magnesium alloy

Reducing extrusion temperature is the effect way to refine the grain and enhance mechanical properties of magnesium alloys.However,it may also stimulate the precipitation of second phase during extrusion of AZ80 alloy,and therefore reduce the hardening effect.The microstructures and mechanical properties of these two types of AZ80 magnesium alloys extruded at 380℃ and 330℃,respectively,on a commercial extruding machine were analyzed.The results indicate that the microstructure with grain size of 6μm is obtained at the extrusion temperature of(330℃.) However,the second phase is precipitated along the grain boundaries during deformation which influence subsequent microstructure evolution and properties.Ultimate tensile strength over 400MPa with an elongation of 8% is achieved after aging treatment of the 380℃-extruded samples.The strong extrusion texture of {0002} is determined and regarded to be responsible mainly for the high properties compared with the grain refinement and precipitation.