Nd对铸态Mg-9Gd-0.5Zr合金组织与力学性能的影响

Effect of Nd on Microstructure and Mechanical Properties of As-cast Mg-9Gd-0.5Zr Alloy

研究了铸态Mg-9Gd-xNd-0.5Zr合金的显微组织演变及力学变化性能。结果表明:Mg-9Gd-0.5Zr合金组织由α-Mg基体、Mg_(5)Gd相和方块状富Gd相组成;添加Nd元素后,Mg-9Gd-xNd-0.5Zr合金的晶粒尺寸明显减小,Mg_(5)Gd相数量减少,骨骼状Mg_(5)Gd_(0.6)Nd_(0.4)相数量增加,方块状富Gd相变化不大。随着Nd含量的增加,基体平均晶粒尺寸先减小后增大,在Nd含量为2.0 wt%时达到最小;继续增加Nd含量,基体平均晶粒尺寸略有增大,骨骼状Mg_(5)Gd_(0.6)Nd_(0.4)相粗化,形成半连续网状。Mg-9Gd-2.0Nd-0.5Zr合金的综合力学性最优,屈服强度约139 MPa、抗拉强度约181 MPa、伸长率约3.8%。

The microstructure evolution and mechanical properties of as-cast Mg-9Gd-xNd-0.5Zr alloy were studied.The results show that the microstructure of Mg-9Gd-0.5Zr alloy consists ofα-Mg matrix,Mg_(5)Gd phase and cuboid Gd-rich phase.The grain size of Mg-9Gd-xNd-0.5Zr alloy significantly reduces after the addition of Nd element.The number of Mg_(5)Gd phases decrease,while the number of skeleton-like Mg_(5)Gd_(0.6)Nd_(0.4) phases increases,and the cuboid Gd-rich phases hardly changes.As the content of Nd increases,the average grain size ofα-Mg matrix decreases firstly and then increases,when the content of Nd reaches 2.0wt%,the effects of grain refinement is excellent.Continued to increase the content of Nd,the average grain size of theα-Mg matrix slightly increases,the shape of Mg_(5)Gd_(0.6)Nd_(0.4) phase changes from skeleton-like to a thick semi-continuous network.The mechanical property of Mg-9Gd-2.0Nd-0.5Zr alloy is the most outstanding,with the yield strength of 139 MPa,the tensile strength of 181 MPa and the elongation of 3.8%.