Study On Microstructure And Properties Of High Strength Wrought Magnesium Alloy

With many advantages, including low specific gravity, high specific strength and specific rigidity, damping capacity, processability, excellent thermal conductivity and electromagnetic shielding, and recyclability, magnesium alloys are considered as eco-structural metal material in the 21st century and interest many researchers. Wrought alloy should be the brightest star in terms of long-term potential applications. Because of excellent properties by the application of heat treatment and the control of compositions. The wrought products such as plate, stick, pipe and plate, can feed a variety of different needs. Compared to other wrought magnesium alloys, ZK60 holds the best properties, while adding the RE series is viewed as a efficient way to improve the mechanism properties.In this paper, more than 7 wrought alloys, ZK60, Mg-Zn-Y, MB25, MZK60, MZK70, MZK80, MZK100 have been studied by smelting, extrusion, heat treatment, mechanical tests and metallography analysis. The process of extrusion can significantly improve mechanical properties because of fine grain obtained via complete dynamic recrystallization. The properties of wrought alloys, especially the plastic property can be greatly improved by adding Y. In this study, the best result is that plastic target 100% higher than before and it is found that added 1% Y is the optimal way because of the effect of Mg3Zn6Y phase .Increased the amount of Zn and treated by solid solution and aging, ZK60 could achieve a high strength, while the plastic property would not change apparently. The effect to properties of heat treatment is complicated. The result can be resorted to the combination of strengthening bringed by solid solution and aging and deterioration by the course grains. For the solid solution strengthening and the later precipitation strengthening is good for properties, while the long time keeping of alloys under elevated te mperature could reduce the properties as the grains would grow. By the processes of ageing, the precipitation of two phase from the supersaturated solid solution could significantly improve alloys' properties. It can greatly increase yield strength of the alloys while keep the tensile strength..Therefore,the component of the modified ZK60 magnesium alloy is Mg-7.0Zn-0.6Zr-1.0Y,and the typical properties areσb=345.66MPa,σ0.2=336.08MPa,δ=18.88% ,respectively.