摘要
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.
By using the first-principles pseudo-potential plane wave method, the energies, electronic structures and elastic constants of B2-Ti50 （Al50-x Crx） （x = 6.25,9. 375,12.5,18.75,25） crystals were calculated. The phase stability of B2-Ti50 （Al50-xCrx） crystals was investigated with the heat of formation, bonding energy and Born Criterion of stability. And the ductile/brittle behaviors of B2-Ti50 （Al50-xCrx） alloys were also characterized and assessed with the Cauchy pressure parameter （C12- C44） and the G/B ratio. The results have shown that B2-Ti50 （Al50-xCrx） crystals are unstable if Cr atom concentration lower than 9.0%. The bulk modulus B, shear modulus G and Young＇s modulus E of Ti50（Al50-xCrx） alloys increase with the increase of Cr, and the ductility is obviously improved as x larger than 12.5 ,compared with γ-TiAl alloy. For the influence of Cr addition on the stability of β0-TiAl-Cr alloys and its strengthening and toughening effect, a reasonable explanation was given on the basis of the density of states （DOS） and electronic density distribution of β0-Ti50（Al5-xCrx） crystals.
出处
《湖南大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
2010年第4期53-57,共5页
Journal of Hunan University:Natural Sciences
基金
国家重点基础研究发展规划资助项目(2006CB605104)
国家自然科学基金资助项目(50771044)
