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采用基于密度泛函理论的第一原理赝势平面波方法,计算了B2-Ti50(Al50-xCrx),x=6.25,9.375,12.5,18.75,25晶体的能量、电子结构和弹性常数,并通过合金形成热、结合能、Born稳定性判据、Cauchy压力参数(C12-C44)和B/C44比值,表征和评判了Cr原子数分数对B2型Ti Al-Cr合金相稳定性、强度与韧脆化倾向的影响.结果表明:当Cr原子数分数大于9.0%时,B2-Ti50(Al50-xCrx)相才能稳定存在,且稳定性随Cr原子数分数增加而升高;同时,随Cr原子数分数增加,合金的体积模最B,剪切模量G和弹性模量E也增大;当Cr原子数分数大于12.5%时,其韧化效果变好.通过电子态密度和价电子密度分布图的比较与分析,初步解释了Cr原子数分数对B2-Ti50(Al50-xCrx)相结构稳定性的影响及其强韧化作用.
The energies, electronic structures and elastic constants of B2-Ti50 (Al50-xCrx), x = 6.25,9.375,12.5,18.75,25 crystals were calculated by the first principle pseudopotential plane wave method based on density functional theory. The thermal stability, strength and ductility of Ti Al-Cr alloy B2 were characterized and evaluated with the formation of heat, bond energy, Born stability criterion, Cauchy pressure parameter (C12-C44) and B / C44 ratio The results show that the B2-Ti50 (Al50-xCrx) phase can exist stably when Cr atom number is more than 9.0%, and its stability increases with the increase of Cr atom number. At the same time, When the atomic fraction of Cr is more than 12.5%, the toughening effect becomes better.According to the electronic state density and the valence electron density distribution The comparison and analysis of the graphs preliminarily explained the effect of Cr atom number fraction on the structural stability of B2-Ti50 (Al50-xCrx) phase and the toughening effect.