L10-TiAl金属间化合物Mn,Nb合金化电子结构的计算

采用第一原理赝势平面波方法计算了L10型TiAl金属间化合物中掺入Mn,Nb后的电子结构和价键结构.通过合金原子形成热得出Mn优先占据Al点阵位置,Nb优先占据Ti点阵位置.Mulliken聚居数分析发现Mn或Nb合金化后,分别降低了(001)和(002)面内的原子间键合强度,掺入Nb还降低了层间的原子间键合强度,而掺入Mn,则使层间原子间键合强度增加.整体上来讲,掺入Mn有利于改善TiAl的室温脆性,而掺入Nb,不利于改善TiAl的室温脆性.

First-principles Study on Electronic Structure of L10-TiAl Intermetallic Compound Alloyed by Mn or Nb

Using first-principles pseudopotential plane-wave method,the electronic structures and bonding characteristics of L1_0-TiAl intermetallic compound alloyed by Mn or Nb is calculated.By analyzing the forming enthalpy,it is found that Mn prefer to occupy the Al sites,while Nb is favored to occupy Ti sites.Mulliken population analysis showed that the bonding strength of(001) and(002) intra-layers in L1_0-TiAl supercell decrease when TiAl is alloyed by Mn or Nb.And Nb addition makes the bonding strength of the interlayer decrease,while Mn addition increase.After compared the ratio of intra-layer bonding strength and interlayer bonding strength,it is found Mn addition is favorable to improve the room temperature brittleness of L1_0TiAl intermetallic compound,while Nb addition is not helpful.