| As one of the lightest structural materials,magnesium alloy is considered to be one of the most promising structural materials because of its abundant resources and reserves,excellent mechanical and casting properties and excellent performance price ratio,so it has attracted wide attention all over the world.The magnesium based eutectic structure has the potential to improve the mechanical properties of magnesium based alloys under certain conditions.In this paper,eutectic magnesium alloy Mg-Zn-X(Nd,Ca)is taken as the research object,and X ray diffraction analysis(XRD),scanning electron microscope(SEM),differential thermal analysis(DSC)and compression test are adopted.The characteristics of the designed eutectic tissue and the mechanical properties of eutectic alloy are studied in depth.Draw the following conclusions:(1)There are two kinds of magnesium based eutectic microstructure in Mg-Zn-Nd alloy eutectic alloy.One is(?-Mg+T1)eutectic structure,the eutectic is honeycomb,and the another is(?-Mg+T2)eutectic structure.The eutectic structure is lamellar eutectic.The composition of phase and eutectic in Mg-Zn-Nd eutectic alloy is analyzed.(2)The eutectic structure composed of ?-Mg+T1 is composed of fine eutectic structure composed of ?-Mg+T1,coarse eutectic structure composed of ?+T2 phase and fine eutectic structure composed of ?-Mg+T2 phase,with self melting point and temperature transition interval.The eutectic structures of ?-Mg+T2 phase in Mg-Zn-Nd alloy,the smaller the eutectic structure,the better the plasticity of the alloy.Mg82.77Zn10.29Nd6.94 has the best comprehensive mechanical properties,the maximum fracture strength is about 500MPa,and the compression elongation is about 9%.(3)The precipitated phase of Mg91.49Nd2.93Ca5.85 is distributed on the substrate in a strip shape,and the eutectic tissue is distributed around the precipitated phase in a laminar form.The granular phase is evenly distributed in each part of the alloy.The addition of Ca in Mg86.8Zn4.89Nd2.86Ca5.45 alloy can effectively refine the microstructure.These fractured phases play a role in relieving stress concentration during plastic deformation of alloy,showing better plasticity.The maximum fracture strength is about 380MPa,and the compression elongation increases to about 10%. |
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