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Ti_(1-x)V_x与Ti_(1-x)Nb_x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a_α减小,c_α/a_α略有增加,ω相晶格参数a_ω及c_/a_ω同时减小,β相晶格参数a_β减小;Ti-Nb合金中随Nb含量的增加,a_α几乎不变,c_β/a_α增加,a_ω增加,c_ω/a_ω减小,。a_β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.
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.
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2009年第9期1042-1048,共7页
Acta Metallurgica Sinica
基金
国家重点基础研究发展计划项目2006CB605104
国家自然科学基金重点项目50631030
广西大学有色金属及材料加工技术教育部重点实验室开放基金6XKFJ-06资助~~
关键词
钛合金
晶格参数
体模量
相稳定性
第一原理计算
Ti alloy, lattice parameter, bulk modulus, phase stability, first-principle calculation
