The Effects Of Nd On Microstructure And Mechanical Properties Of The ZM6 Alloy

This article researches the effect of Nd on the microstructure and mechanical propertyes of ZM6 alloy, by means of optical microscope, scanning electron microscope etc. through microstructure observation for ZM6 alloy sample of different Nd content, analysis of fracture appearance, testing for mechanical property under room temperature and 250℃high temperature, and testing for corrosion under different temperatures and mediums. The following conclusions can be obtained from experimental results.Adding Nd can diminish the crystal grain dimension of the structure of ZM6 alloy at a certain extent, but it doesn't have obvious effect on ZM6 alloy crystal grain and dimension under casting condition. The dimension of the crystal grain is minimum when the content of Nd is 2.5%. After Nd is added, the alloy elements mainly concentrate on grain boundary, and the educt on boundary is mainly the Mg₁₂(Nd,Zn).Mix- feature of cleavage step, laniating ridge and malleable dimple can be observed from stretching fracture under room temperature. Along with the content adding of Nd, laniating ridge changes to cleavage step, and the depth of the step is deepening. Heat treatment can improve grain boundary condition and make the element of Nd distribute dispersively in the structure, so as to improve the intensity of grain boundary and improve the performance.As the content of Nd is increased, the tensile strength of the alloy at high temperature is increased, and the elongation is decreased while hardness increased, the hardness can be increased by the heat treatment. As the content of Nd is increased, the tensile strength of the alloy at high temperature is increased, and the elongation is first increased and then decreased and the creep strength is firstly improved to a great extent and then decreased slowly. When the content of Nd exceeds 1.2%, the increase rate of tensile strength of the alloy at high temperature is slower; When the content of Nd is between 0.5% and 1.2%, the elongation of the alloy goes to the highest; When the content of Nd is up to 1.6%, the creep strength of the alloy comes to the highest.Under the same temperature, corrosion rate is increased when the content of Nd is between 1.2 and 1.6 %. Corrosion rate of the alloy is increasing while temperature is increasing. The corrosion performance is the same when alloy is in weak acid and neutral medium.