( 湖南大学 材料科学与工程学院，长沙 410082)
摘 要: 采用第一原理赝势平面波方法研究了NiAl-X(X为3d过渡金属)合金体系的几何与电子结构。通过合金形成能的计算与分析发现：合金化元素的外层价电子数对其在B2-NiAl中的占位有非常明显的影响，低价电子数的前过渡金属Sc、Ti、V与后过渡金属Zn主要占据Al原子位，具有未满d壳层高价电子数的Mn、Fe、Co则主要占据Ni原子位，而含有半满或满d壳层的Cr与Cu，则既可占据Ni原子位也可占据Al原子位，但倾向于占据Ni原子位。随着合金化元素外层价电子数的增加，3d过渡金属优先占据Ni原子位的趋势增大，至Mn时达到最大，然后随着价电子数的进一步增加，这种趋势逐渐减小。通过对这些合金化元素价电子态密度图的变化，说明3d过渡金属在B2-NiAl中的占位优先趋势。
关键字: B2-NiAl；电子结构；赝势平面波方法；占位
substitution of 3d transition metal elements
in NiAl intermetallic compound
（ School of Materials Science and Engineering,
Hunan University, Changsha 410082, China）
Abstract: Site substitutions of 3d transition metal(TM) elements in NiAl intermetallic compound were investigated with the first principle methods based on plane-wave pseudopotential theory. By calculating the formation energy of NiAl alloyed by X element, the site preference were investigated. The results show that the former and later TM elements with low valence electron numbers of Sc, V, Ti and Zn mainly substitute for the Al site in NiAl. The high valence electron numbers elements with un-filled d-shell, e.g. Mn, Fe and Co, primarily substitute for the Ni site in NiAl. The elements with semi-filled or filled d-shell such as Cr and Cu can substitute for either the Ni site or the Al site in NiAl, but preferentially tend to the Ni site. And with the increase of valence electrons in the outer shells in 3d TM, the site preference to substitute for the Ni site increases before Mn and then decreases after Mn. From above results, a reasonable explanation has been given on the analysis basis of the states density of valence electrons of these 3d TM elements in NiAl.
Key words: B2-NiAl intermetallic compound; electronic structure; plane-wave pseudopotential method; site substitution
