Nd含量对Mg-5.0Y-xNd-0.6Zr合金组织性能的影响  

Effects of Nd content on microstructure and properties of Mg-5.0Y-xNd-0.6Zr alloy

作　　者：李伟[1] 高家诚[1] 

机构地区：[1]重庆大学国家镁合金材料工程技术研究中心材料科学与工程学院,重庆400044

出　　处：《重庆大学学报（自然科学版）》2011年第3期50-56,63,共8页Journal of Chongqing University

基　　金：国家自然科学基金资助项目(30670562)

摘　　要：采用光学显微镜(OM)、扫描电镜(SEM)、差示扫描量热分析(DSC)、X射线衍射(XRD)和室温拉伸研究了稀土Nd含量对Mg-5.0Y-xNd-0.6Zr(x=0,1.0,1.8,2.6,3.4,4.2,质量分数/%)合金铸锭微观组织和力学性能的影响。结果表明:随着Nd含量增加,合金的平均晶粒尺寸从33.5μm减小到19.2μm,基体内固溶的Y和弥散分布的Mg24Y5颗粒减少,晶界上不连续网状分布的β相增多;合金的抗拉强度先增大后减小,而屈服强度先增大后趋于不变,其最大值分别为214.5MPa和102.8MPa,延伸率和断面收缩率基本呈直线下降,分别从16.4%和23.8%降低到4.9%和2.7%;凝固过程中Nd、Y原子在固液界面前沿富集造成成分过冷度增大以及它们对晶粒生长的抑制作用增强是Nd细化合金晶粒的主要机理。Effects of Nd content on the microstructure and mechanical properties of Mg-5.0Y-xNd-0.6Zr（x=0,1.0,1.8,2.6,3.4,4.2,mass fraction/%）alloy casts are investigated by optical microscopy（OM）,scanning electron microscopy（SEM）,differential scanning calorimetry（DSC）,X-ray diffractometry（XRD） and tensile tests.The results reveal that increasing Nd content can refine the average grain size of alloys from 33.5 μm to 19.2 μm,reduce the number of Y atom in α-Mg and Mg24Y5 grain dispersed in the matrix,and increase β phase with the distribution of discontinuous network in crystal boundary.With the increase of Nd content,the tensile strength keeps rising first and subsequently falling,and the yield strength has a sharp increase at first and then gradually becomes constant,with the maximum values of 214.5 MPa and 102.8 MPa,respectively.The elongation and section shrinkage linearly decrease from 16.4% and 23.8% to 4.9% and 2.7% with the increase of Nd content.The mechanism of grain size refinement of Mg-5.0Y-xNd-0.6Zr alloys can be explained by Nd and Y enrichment in the forefront of solid-liquid interface during solidification process which enhances the supercooling of the solute rich zone and inhibits the crystal grain growth.

关 键 词：MG-Y-ND-ZR合金 ND 显微组织 力学性能 晶粒细化 

分 类 号：TG146.2[一般工业技术—材料科学与工程]