Existence patterns of Dy in β-NiAl from first-principles calculations  

作　　者：Tian Zhang Hong-Bo Guo Sheng-Kai Gong Hui-Bin Xu 

机构地区：[1]School of Materials Science and Engineering,Beihang University

出　　处：《Rare Metals》2016年第4期356-360,共5页稀有金属（英文版）

基　　金：financially supported by the National Natural Science Foundation of China(Nos.50771009,50731001,and 51071013);the National Basic Research Program of China(No.2010CB631200)

摘　　要：Intermetallic compound β-NiA1 is a promising material in high temperature applications due to its high melting temperature, high strength, low density, and good oxidation resistance. However, its application remains limited because of its relatively poor cyclic oxidation resistance. Addition of reactive element （RE） Dy can improve the cyclic oxidation of NiA1 alloys significantly. However, the mechanism of Dy addition is not clear. Even the existence pattern of Dy in NiA1 is unspecified. Therefore, in the present study, the impurity formation energies of Dy in stoichiometric NiA1, Ni-rich, and Al-rich NiA1 for the substitution cases were studied by first-principles density functional theory. The results show that Dy could hardly substitute for either Ni or A1 atoms in NiA1. However, calculations for dissolution energies show that Dy could be easily dissolved in AI vacancies in all three types of NiA1, which provides a new existence pattern of Dy in NiA1 beyond experimental detection.Intermetallic compound β-NiA1 is a promising material in high temperature applications due to its high melting temperature, high strength, low density, and good oxidation resistance. However, its application remains limited because of its relatively poor cyclic oxidation resistance. Addition of reactive element （RE） Dy can improve the cyclic oxidation of NiA1 alloys significantly. However, the mechanism of Dy addition is not clear. Even the existence pattern of Dy in NiA1 is unspecified. Therefore, in the present study, the impurity formation energies of Dy in stoichiometric NiA1, Ni-rich, and Al-rich NiA1 for the substitution cases were studied by first-principles density functional theory. The results show that Dy could hardly substitute for either Ni or A1 atoms in NiA1. However, calculations for dissolution energies show that Dy could be easily dissolved in AI vacancies in all three types of NiA1, which provides a new existence pattern of Dy in NiA1 beyond experimental detection.

关 键 词：Existence pattern DY A1 vacancies FIRST-PRINCIPLES 

分 类 号：TG146.15[一般工业技术—材料科学与工程] TB383[金属学及工艺—金属材料]