Mechanical Behavior Of Extruded Mg-Al And Mg-Zn Based Alloys

Due to their superior performances in weight reductions, energy source saving and reliability enhancement, both development and applications of magnesium alloys have been considerably focused. In recent years, with the rapid progress of automotive and electronic industries, a number of magnesium alloy components have been manufactured to replace those made of plastics, aluminum alloy and steel ones. It can be expected that magnesium alloys will become the most important lightweight structural materials in commercial metal materials. Wrought magnesium alloys can exhibit the higher strength and better plasticity than cast magnesium alloys, and show the more significant potential in further applications of magnesium based materials. Obviously, researches on microstructures and properties of wrought magnesium alloys can not only establish theoretical foundation for new development of wrought magnesium alloys, but also provide reliable bases for safe design and reasonable usage of wrought magnesium alloy components.In this paper, the tensile and low cycle fatigue behaviors of extruded AM50 and AZ91 magnesium alloys with different processing statuses are investigated. The influence of testing temperature and heat treatment on both tensile and fatigue properties of extruded AM50 and AZ91 magnesium alloys are determined. Moreover, the superplastic deformation behavior of extruded AZ81 and equal-channel-angular-pressed ZK40 magnesium alloys has also been studied. The effect of testing temperature on the superplastic property of two alloys and corresponding superplastic deformation mechanism are discussed.The tensile experimental results show that for the AM50 and AZ91 alloys subjected to different processing and treatment, the ultimate tensile and yield strengths decrease while elongation to failure obviously increases with increasing test temperature. After the solid solution treatment (T4), the growth of grains occurs, which leads to a decrease in mechanical properties of two alloys. When the aging is applied following solid solution treatment (T6), the ultimate tensile and yield strengths of two alloys will get enhanced because the fine secondary phase particles precipitate The aging directly following hot extrusion (T5) can result in the precipitation of those strengthening phases such as Mg₁₇Al₁₂, and thus the tensile properties of the AM50 alloy at room and elevated temperatures as well as the tensile properties of the AZ91 alloy at room temperature get increased. Fracture surface analysis revealed that the extruded AM50 and AZ91 alloys with different processing statuses exhibit a characteristic of mixed ductile and brittle fracture during tension at room temperature. At...