中文摘要：

利用基于密度泛函理论的第一原理精确Muffin—Tin轨道（EMTO）方法结合相干势近似（CPA），研究了Ti1—xVx与Ti1-xNbx合金中α（α＇）,ω及β相的晶格常数、体模量及相稳定性随成分的变化．结果表明，Ti—V合金中随着V含量的增加，α（α＇）相晶格参数αα。减小，cα/aα。略有增加，ω相晶格参数aω及cω/aω同时减小，β相晶格参数aβ减小；Ti—Nb合金中随Nb含量的增加，aα几乎不变，cα／aα增加，aω增加，cω/aω减小，aβ几乎不变．随V及Nb含量的增加，ω与β相的晶格错配度线性增加．V和Nb均能提高三相的体模量，且增加β相对于其它两相的稳定性．

英文摘要：

Although Ti-V and Ti Nb binary systems are subjected to many investigations, there remain some issues open for discussion, among which are the lattice parameter misfit and phase boundary between the non-equilibrium ω and β phases. On the other hand, the experimental elastic moduli of the non-equilibrium phases are rarely reported due to the difficulty of the measurement. In this paper, the lattice parameters, bulk moduli and phase stabilities of α（α＇）, ω, and β phases of binary Ti V（Nb） alloys are investigated by the use of first-principles exact Muffin Tin orbital method in combination with coherent potential approximation. It is shown that, with the increase in the V content, the lattice parameter aα of the cα（α＇） phase decreases, whereas cα/aα slightly increases; aω and cω/aω of the ω phase and aβ of the β phase decrease. For Ti-Nb alloy, with increasing Nb content, aα keeps almost unchanged whereas cα/aα increases; aω increases and cω/aω deceases; aβ does not change significantly. The lattice parameter misfit between the w andβ phases increases with increasing V or Nb content. Both V and Nb harden the bulk modulus of Ti and improve the phase stability of the phase relative to the α（α＇） and ω phases. The theoretical predictions are compared in detail with the available experimental data.