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采用密度泛函的赝势平面波法,对(TiAl)1-xNbx(x=0,1/16,1/12,1/8,1/4)掺杂相的晶体进行了几何优化,计算了弹性常数、电子结构和布居数等,系统分析了掺杂对几何结构、电子结构和键强的影响机制。结果表明:Nb带来的几何变化对体系塑性性能的影响较小;随着Nb的增加,B/G值出现波动,当Nb含量为8.33%～12.5%体系塑性和各向同性性质较好;且随着Nb的增加,体系共价键强度大幅削减,Ti-Al和Nb-M(M=Ti,Al)等杂化键成分增强,在峰区增多的同时赝能隙先减小后增大,能带展宽整体变窄,降低了体系共价性和方向性,布居分析数据也表明空间成键的方向性得以均化,与电子结构分析一致。综上分析,当Nb摩尔含量在8.33%～12.5%时有利于室温塑性的改善。
The crystal of (TiAl) 1-xNbx (x = 0, 1/16, 1/12, 1/8, 1/4) doped phase was geometrically optimized using density functional wave pseudopotential plane wave method. The elastic constants, the electronic structure and the number of occupancy, etc., Systematically analyzed the mechanism of doping on the geometry, electronic structure and bond strength. The results show that the influence of Nb on the plasticity is less affected by the geometric changes of Nb. The B / G value fluctuates with the increase of Nb content. When the content of Nb is 8.33% ~ 12.5%, the plasticity and isotropy of the system are better. And with the increase of Nb, the covalent bond strength of the system is greatly reduced, the hybrid bond components such as Ti-Al and Nb-M (M = Ti, Al) are enhanced, while the pseudo- Large, narrow band broadening overall, reducing system covalence and directionality, and population analysis also shows that the directionality of spatial bonding can be averaged, consistent with the electronic structure analysis. In summary, when the Nb molar content of 8.33% ~ 12.5% at room temperature plastic is conducive to improvement.