B2型Y基金属间化合物YX(X=Ag,Cu,In,Rh)延性预测  

Prediction of the Ductility of B2 Type Yttrium-Based Intermetallic Compounds

作　　者：庄厚龙[1] 彭平[1] 周惦武[1] 刘金水[1] 

机构地区：[1]湖南大学,湖南长沙410082

出　　处：《稀有金属材料与工程》2006年第2期247-252,共6页Rare Metal Materials and Engineering

基　　金：国家重点基础研究发展规划资助项目(G2000067105);教育部博士点基金项目(20020530012)

摘　　要：采用第一原理赝势平面波方法——CASTEP程序计算了4种B2型Y基金属间化合物YX(X=Ag,Cu,In,Rh)的部分弹性性质,计算结果与文献报道值基本一致。通过Pugh定律、Cauchy压力和泊松比等经验判据,分析并预测了它们的脆性/延性,其延性高低次序为:YRh>YAg>YCu>YIn。电子结构分析表明:这4种金属间化合物良好的延性源于其较强的金属键,而不同程度的Y(d)-X(p)电子杂化则导致了其延性的差异。YIn中因In的p电子较多,杂化程度高,共价键方向性强,因而延展性最低,而YRh则由于存在Y(d)-Rh(d)电子间强的相互作用,增强了其金属键作用,因而延性最好。Using the first-principles pseudo-potential plane-wave CASTEP code, the electronic structures and the elastic constants of C11, C12, C44 as well as the bulk modulus Bo of yttrium-based intermetallic compounds, i.e., YX （X= Ag, Cu, In, Rh, were calculated. As comparing with the experimental and other theoretical results of YAg and YCu, a good agreement between this work and literatures has been found. Based on several empirical criterions, i.e., Pugh rule （the ratio of shear modulus to bulk modulus G/B0）, Cauchy pressure parameter C12-C44 and Poisson＇s ratio v, the ductility or brittleness of these intermetallic compounds are characterized and analyzed. The experimental result of which YAg has a better ductility than YCu has been verified, and the order of ductility as follow YRh 〉YAg〉YCu〉YIn is also further predicted. The analysis of electronic structures of YX （X= Ag, Cu, In, Rh） indicates the good ductility of these intermetallic compounds originates from their strong metallic bonding. And it is found the discrepancy of ductility in these intermetallic compounds results from the different extent of hybridization between Y（d） and X（p） electrons. Because of In of YIn having the most p electrons relative to other X elements in YX intermetallic compounds, the strongest hybridization between Y（d）-X（p） electrons causes a high directionality of covalent bonding in YIn, and then its ductility is the lowest. For YRh intermetallic compound, its better ductility can attribute to a enhanced metallic bonding between Y（d） and Rh（d） electrons.

关 键 词：Y基金属间化合物 脆性/延性 第一原理 电子结构 

分 类 号：TG111[金属学及工艺—物理冶金]