(1. 江蘇理工學院 材料工程學院，常州 213001；
2. 池州學院 機械與電子工程系，池州 247000；
3. 中南大學 材料科學與工程學院，長沙 410083)
摘 要: 運用第一性原理平面波贗勢方法計算金屬間化合物L12-Al3Sc的基本物性，并通過計算點缺陷形成能推測L12-Al3Sc點缺陷的主要存在形式，結合電荷密度和態(tài)密度的分析揭示L12-Al3Sc的成鍵行為。結果表明：L12-Al3Sc的晶格常數為4.107 ？，體模量為86.5 GPa，形成焓為-43.83 kJ/mol。L12-Al3Sc的點缺陷主要為Al亞晶格上的Al空位和Sc反位缺陷。L12-Al3Sc中Sc空位與Al反位缺陷的形成能較為接近，表明富Al合金中Sc空位和Al反位缺陷易于共同存在；Sc反位缺陷的形成能小于Al空位的，表明富Sc合金的點缺陷為Sc反位缺陷。L12-Al3Sc的成鍵電荷密度呈紡錘狀，表現出Sc d-Al p的軌道雜化效應，其雜化軌道主要為Sc dz2-Al pz軌道雜化。
關鍵字: L12-Al3Sc；點缺陷結構；第一性原理計算；成鍵行為；雜化
（1. School of Materials Engineering, Jiangsu University of Technology, Changzhou 213001, China;
2. Department of Mechanics and Electronic Engineering, Chizhou University, Chizhou 247000, China;
3. School of Materials Science and Engineering, Central South University, Changsha 410083, China）
Abstract:The first-principles pseudopotential plane-wave calculation was used to study the energies and the electronic properties of point defects for L12-Al3Sc intermetallic. According to the calculation and comparison of the formation energy of point defect structures, the geometrical configuration of point defects in L12-Al3Sc intermetallic was analyzed. Combining with densities of states and charge densities, the effect of bonding behavior on electronic structure was investigated emphatically. The results show that the lattice constant of L12-Al3Sc is 4.107 ？，bulk modulus is 86.5 GPa, and formation enthalpy is -43.83 kJ/mol. These calculation results also suggest that the point defects in the Al sublattices, i.e., Al vacancy and Sc anti-site, are more favorable than those in the Sc sublattices for the stoichiometric compound Al3Sc in the L12 structure, but Sc vacancy and Al anti-site defect coexist in rich-Al alloy, and mainly Sc anti-site defect can be found in rich-Sc alloy. The Al vacancy-induced charge density shows the spindle-like bonding characteristic, and Sc dz2-Al pz orbital hybridization is depicted.
Key words: L12-Al3Sc; point defect structures; first-principles calculation; bonding behavior; hybridization
