过渡金属元素在NbCr2 Laves相中晶格占位的第一性原理计算

采用全势线性缀加平面波方法和广义梯度近似对过渡金属元素V，Ti和W在C15结构的NbCr2 Laves相中的晶格占位进行了研究．计算结果表明，过渡族元素V，Ti和W在NbCr2中的晶格占位不尽相同．V优先占据NbCr2中Cr的晶格位置，W占据Cr的晶格位置的倾向很弱，而Ti优先占据Nb的晶格位置；生成热计算结果表明，当V占据NbCr2中Cr的晶格位置和Ti占据Nb的晶格位置时，可以使NbCr2Laves相更加稳定．结合电子结构计算结果对上述占位特性进行了讨论．

FIRST-PRINCIPLES CALCULATION OF THE SITE SUBSTITUTION OF TRANSITION METAL ELEMENTS IN THE NbCr2 LAVES PHASE

Site occupancies of transition metal elements, V, Ti and W, in the C15 NbCr2 Laves phase were investigated by the full-potential linearized augmented plane-wave-method within the generalized gradient approximation. The calculated results show that V preferentially substitutes the Cr sites, W has a weak site preference on the Cr site, and Ti preferentially occupies the Nb sites in NbCr2. The calculations of the formation heat show that only V occupying the Cr sites and Ti occupying the Nb sites can stabilize NbCr2 Laves phase. The site substitution behaviors of those transition metal elements in NbCr2 are also discussed with the calculated electronic structure of the ternary Laves phases.