3d过渡金属在L10-TiAl中占位的第一原理计算

采用第一原理赝势平面波方法研究TiAl—X（X为3d过渡金属）超胞合金体系的几何、能量与电子结构。通过计算、比较、分析Ti7A18X与Ti8Al7X超胞的合金形成能，得出3d过渡金属在L10—TiAl合金中的占位情况：合金化元素的外层电子数，特别是外层的d电子数对其在L10-TiAl合金中的占位有非常明显的影响，d电子数较少的前过渡金属Sc、V和Cr主要优先占据Ti原子位，而d电子数较多甚至是满d壳层的Mn、Fe、Co、Ni、Cu和Zn则主要优先占据Al原子位。与相关理论研究比较，对Cr元素在L10-TjAl合金中占据情况得出不同结论。对于合金化元素在L10-TiAl合金中占据不同亚点阵的情况，还从电子分波态密度角度，很好地解释了其产生的电子机制。

First-principles Calculation for Site Substitution of 3d Transition Metal Elements in L10-TiAl Intermetallic Compound

Site substitution of 3d transition metal（TM） elements in L10 -TiAl intermetallic compound were investigated with the first- principle method based on plane -wave pseudopotential theory. By calculating the formation energy of L10 -TiAl alloyed by TM elements, the site preference were investigated. The results show that TM elements which have few d electrons, such as Sc, V and Cr mainly subsititute for the Ti site in L10 - TiAl, the others which have many d electrons or even have a closed d shell, e.g. Mn、Fe、Co、Ni、Cu and Zn primarily subsititute for the A1 site in L10 - TiAl. The site sub- stitution of Cr element in L10 -TiAl is different from relevant theory research. 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 L10 -TiAl intermetallic compound.