稀土元素Ce对NiAl金属间化合物结构及力学性能的影响

基于密度泛函理论的第一原理方法,使用VASP代码包计算分析稀土元素Ce对金属间化合物NiAl结构及力学性能的影响。结果表明:Ce原子在NiAl中优先占据Al位;Ce掺杂后引起NiAl晶胞畸变,晶格常数增大。通过电荷密度图和态密度图分析,Ce与邻近的Ni、Al原子发生相互作用并存在轨道杂化成键。计算弹性常数、弹性模量等物理量,结果表明,Ce使得NiAl的硬度降低,刚性变弱,利用Pugh判据分析得出Ce能够改善NiAl的韧性。随着Ce掺杂浓度的增加,NiAl晶格常数增大的幅度提高,NiAl的韧性越好,但其硬度和刚性降低的幅度也越大。

Doping effect of Ce on structure and mechanical properties of NiAl intermetallics

Based on the first-principles method of the density functional theory, the study analyzed the influence of rare earth element Ce on the structure and mechanical properties of NiAl intermetallics. The study was needed to use Vienne Ab-inito Simulation Package(VASP). The results show that Ce preferentially occupies the Al site in NiAl by comparing formation energy of Ce occupying the Ni site and Ce occupying the Al site. After Ce occupied the Al site, the NiAl supercell is changed, lattice constant is augmented, and as the concentration of Ce increases, the degree of augment in the lattice constant of NiAl gets larger. By analyzing the figures of charge density and state density, it is found that Ce interacts with adjacent atoms and it exists the orbital hybridization and bonding among them. Furthermore, some physical parameters, such as elastic constants, elastic modulus,etc., were calculated. The results show that Ce reduces the hardness and weakens the stiffness of NiAl. However, through Pugh’s empirical criterion, it’s found that Ce improves the toughness of NiAl. With increasing the concentration of Ce, the toughness of NiAl is better, but the degree of reduction in the hardness and stiffness is larger.