Ce和V双掺杂对γ-TiAl基合金塑性和电子结构的影响  

Effects of Ce and V Co-doping on Plasticity and Electronic Structures of γ-TiAl Based Alloys

作　　者：宋庆功 朱燕霞[2] 王丽杰 顾威风 胡雪兰 康建海[1] Song Qinggong;Zhu Yanxia;Wang Lijie;Gu Weifeng;Hu Xuelan;Kang Jianhai(Institute of Low Dimensional Materials and Technology,College of Science,Civil Aviation University of China,Tianjin 300300,China;Sino-European Institute of Aviation Engineering,Civil Aviation University of China,Tianjin 300300,China)

机构地区：[1]中国民航大学理学院低维材料与技术研究所,天津300300 [2]中国民航大学中欧航空工程师学院,天津300300

出　　处：《稀有金属》2019年第9期942-951,共10页Chinese Journal of Rare Metals

基　　金：国家自然科学基金项目(51201181);中国民航大学自然科学基金项目(08CAUC-S02)资助

摘　　要：γ-TiAl基合金是具有优异综合性能和重要应用价值的高温结构材料。室温塑性不足抑制了这类合金的广泛应用。原子替位双掺杂是改善其室温塑性的有效方法之一。采用基于密度泛函理论的第一性原理方法,计算研究了Ce和V原子替位双掺杂γ-TiAl基合金的几何结构、总能量、弹性常数、电子态密度、重叠布居数、电荷密度和差分电荷密度等,并计算了原子平均形成能、弹性模量比、赝能隙。由原子平均形成能和Born-Huang判据可知,各个Ce和V替位双掺杂γ-TiAl基合金体系都具有能量稳定性和力学稳定性。由弹性模量比预测,各个Ce和V替位双掺杂γ-TiAl基合金体系的塑性均有明显改善。通过对典型合金体系Ti8Al6CeV的重叠布居数和电荷密度分析,揭示材料塑性改善的内在因素是:Ce和V替位双掺杂使Al-3p与Ti-3d轨道间的共价结合显著弱化;Ti-d与Ti-d轨道间的杂化显著增强;而Al与Al原子间的共价结合明显弱化。γ-TiAl based alloys are high-temperature structural materials with excellent comprehensive properties and important application values, while their insufficient plasticity at room temperature inhibits the widespread use of such alloys. Atomic substitution co-doping is one of the effective methods to improve the plasticity of room temperature. The geometric structures, total energies, elastic constants, electronic densities of states, overlap populations, charge densities and charge density differences of Ce and V atoms substitution co-doping γ-TiAl based alloys were investigated by using the first-principles method based on the density functional theory. On this basis, the average formation energies of the atoms, elastic modulus ratios, and pseudo-gaps of the systems were calculated and studied. According to the average formation energy and Born-Huang criterion, all of the Ce and V substitution double doping γ-TiAl based alloys had energy stability and mechanical stability. The significant improvement of plasticity of Ce and V substitution co-doping γ-TiAl systems was predicted by their elastic modulus ratios. The analysis about the overlap population and charge density of the typical alloy system Ti8Al6CeV suggested the intrinsic factors that improved the plasticity of the materials were: the Ce and V atoms substitution co-doping significantly weakened the covalent bonds of Al-3 p and Ti-3 d orbitals. The hybridigation bonds between Ti-d and Ti-d orbitals were significantly enhanced, and the covalent bonds between Al and Al atoms were significantly weakened.

关 键 词：Γ-TIAL基合金 塑性 电子结构 化学键 第一性原理 

分 类 号：TG146.2[一般工业技术—材料科学与工程]