部分bcc和fcc金属点缺陷性能的第一原理计算

First Principles Calculation of the Point Defects for Some Bcc and Fcc Metals

缺陷对金属及合金的物理和机械性能有显著的影响.点缺陷如空位和间隙性能有助于理解金属和合金的热力学及动力学行为.使用第一原理软件CASTEP模块计算了体心立方结构金属V,Cr,Fe,Nb,Mo,W和面心立方结构金属Ni,Rh,Pd,Cu,Zn,Ag的单空位形成能、结合能、自间隙形成能.计算结果表明:所有结合能的计算值均高于实验值,空位形成能的结果与其他计算方法的结果比较接近;对于bcc结构,<110>或<111>哑铃间隙构型能量最低,结构最稳定,与其他计算方法结论一致;fcc结构的<100>哑铃或八面体间隙构型能量最低,结构最稳定;空位形成能的值大约是结合能的1/3-1/4;间隙形成能与体弹性模量B有关,随着B的增大而增大.

The defects significantly effect on the physical and mechanical properties of materials. The properties of vacancies and interstitials arehelpful in understanding the thermodynamic and kinetic behavior of materials and alloys. In this paper the vacancy formation energy, interstitial formation energy, and cohesive energy were calculated by the first principles code CASTEP, for bee transition metals such as V, Cr, Fe, Nb, Mo, and W, and for fee metals such as Ni, Rh, Pd, Cu, Zn, and Ag. The calculation results show that the calculated cohesive energy is larger than the published experimental results; and the vacancy formation energy agrees with other theoretical calculations; and the energy of 〈 110 〉 or 〈 111 〉 dumbbell interstitial configuration is the smallest in the bcc metals,so 〈 110 〉 or 〈 111 〉 dumbbell configuration is stable; and in the fcc metals, 〈100 〉 dumbbcU or octahcdral interstitial configuration is the most stable; and the ratio of vacancy formation energy Ev and cohesive energy Ec is 1/3-1/4; and the relationship between interstitial formation energy and bulk modulus B is that when B increases,Ei also increases.