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基于第一原理赝势平面波方法和虚拟晶体势函数近似(VCA),提出了一种计算Ti-Al-Nb合金V合金化的形成热和力学性能的方法和模型。计算结果表明:Ti-Al-Nb合金V合金化时V倾向占据O-Ti2AlNb晶体的Nb点阵位。合金化产物O-Ti-22Al-[Nb(27-x)Vx]晶体的弹性模量理论计算值与室温测量值非常接近,并通过计算预测了当V合金化浓度x在1%~3%变化时晶体的弹性模量逐渐降低。采用Pugh判据B/G和B/C44比值表征和评判了V合金化浓度对O-Ti-22Al-27Nb晶体延性的影响。计算表明:V合金化浓度为1%~2%时不能改善O-Ti-22Al-27Nb晶体的延性,但当V浓度为3%时能显著增加O-Ti-22Al-27Nb的延性。从理论数据和实验结果对比来看,这种计算Ti-Al-Nb合金V合金化的形成热和力学性能的模型和方法比较准确和可靠,在为实验结果提供理论支撑同时,还可对不同V合金化浓度的合金性能做出预测。
Based on the first-principle pseudopotential plane wave method and virtual crystal potential function approximation (VCA), a method and a model for calculating the formation thermal and mechanical properties of V-alloying Ti-Al-Nb alloy were proposed. The calculated results show that the V tendency of V-alloying Ti-Al-Nb alloy occupies the Nb lattice of O-Ti2AlNb crystal. The theoretical calculated value of the elastic modulus of the alloying product O-Ti-22Al- [Nb (27-x) Vx] crystal is very close to the measured value at room temperature and it is predicted by calculation that when the V alloying concentration x is between 1% and 3% Changes in the elastic modulus of crystals gradually decreased. The Pugh criterion B / G and B / C44 ratios were used to characterize and evaluate the effect of V alloying on the ductility of O-Ti-22Al-27Nb crystal. The results show that the ductility of O-Ti-22Al-27Nb can not be improved by the addition of 1% -2% V alloy, but the ductility of O-Ti-22Al-27Nb can be significantly increased when V concentration is 3%. From the comparison of theoretical data and experimental results, this model and method for calculating the formation thermal and mechanical properties of V alloyed Ti-Al-Nb alloy are more accurate and reliable. While providing theoretical support for the experimental results, V alloying concentration of alloy properties to make a prediction.