Influence Of Nd And Y On Microstructure And Mechanical Properties Of Mg-5Zn Alloys

Magnesium alloy is the lightest metal among practical metal material. Magnesium alloy has the high relative intensity, the high relative stiffness, the better diamagnetism, the higher electronegativity and thermal conductivity, good property of shock absorption and good machinability. But the strength of Magnesium alloy is rather low, which has been the main reason in hindering the development of Magnesium alloy. So improving the strength of magnesium alloy and having a good comprehensive performance, which becomes one of the focuses of the current study on the materials. In this paper the method of rare earth elements alloying is used for improving the strength of magnesium alloy. With the pure magnesium being the raw material, adding zincification and the different proportional mixed rare earth to which, the different component of casting and extruding(the heat extrusion ratio is 17.5:1) of the deformation rare earth magnesium alloy are prepared out . This paper studies the effects of zinc and rare earth elements on the microstructure and the mechanical properties of the alloy, and explores the strengthening mechanism.The results showed that, the organization of casting states of Mg-5Zn alloy was refined by adding the RE, but with the contents of the RE increasing the refining effects decreased. After heat extruding deformation at 350oC, the cast structure of all the casting states magnesium alloy has become deformation microstructure: the grains get refined significantly and the second phases distributs homogeneously. The higher content of RE,the finer the grains, the more significant the fiber-texture microstructure. But the increasing of the number of the second phases leads to enhance the brittleness of the alloy. The performance test showed that with the increasing of the content of the RE, the strength of the deformed magnesium alloy present curved change. The highest strength at room temperature and high-temperature is obtained when the content of the RE is 4%. The deformed magnesium alloys are aged treatment, but the organization and the mechanical performance are not change significantly. It is determination that the alloy is not strengthened by heat treatment.It is analysis that the adding of the rare earth and the treatment of extrusion has a great effect on the comprehensive properties of the Mg-Zn alloy. It can fine the grains and purify the grain boundary, which improve the strength and the plasticity of the alloy.