采用正交试验方法,通过砂型铸造制备9种不同成分的Mg-Nd-Gd-Zn-Zr系镁合金.研究该系列镁合金的铸造组织和室温力学性能,并通过对力学性能试验数据的分析,研究主要合金化稀土元素Gd和Nd的作用.研究发现:该系列镁合金铸态组织为α-Mg基体和Mg_(12)Nd化合物.经过固溶处理后,铸态组织中晶界上的化合物大部分溶入基体,但在晶界上还有一些颗粒状的化合物.Gd含量越高,合金的室温抗拉强度、屈服强度和延伸率就越高.Nd含量越高,抗拉强度和屈服强度也越好,但延伸率在Nd含量超过2水平(2.85%)后会降低.抗拉强度和屈服强度受Nd含量的影响最大,Gd含量的影响次之.Zn含量越高屈服强度越高,但抗拉强度和延伸率降低,其中延伸率受Zn含量的影响最大.
With the method of orthogonal experiment, nine kinds of Mg-Nd-Gd-Zn-Zr magnesium alloys with different composition were prepared by sand casting. The cast microstructures and mechanical properties of Mg-Nd-Gd-Zn-Zr magnesium alloys were investigated, and the effects of Gd and Nd element on mechanical properties at room temperature were also studied by analyzing experiment results of mechanical properties. It is found that the as-cast microstructure of Mg-Nd-Gd-Zn-Zr alloys consists of α-Mg grains with Mg_(12)Nd phase in the grain boundary. After the solid solution treatment, almost all of the phases in the grain boundary dissolved in the matrix; however, there was still discontinued Mg_(12)Nd phase in the boundary. The increasing Gd content results in higher ultimate strength, yield strength and elongation. With increasing Nd content, the ultimate strength, the yield strength and the elongation increase. However, the elongation decreases when Nd is over 2.85 wt%. The effects of Nd content on the ultimate strength and yield strength of Mg-Nd-Gd-Zn-Zr alloy at room temperature are more significant than that of Gd. When Zn content is increased, the yield strength increases, but the ultimate strength and the elongation decreases. And Zn content has the greatest impact on elongation.
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