B_(2)-NiAl晶体Cr微合金化力学效应理论研究

Theoretical Study on the Mechanical Effect of B_(2)-NiAl Crystal Cr Microalloying

基于虚拟晶体势函数(VCA)近似,采用密度泛函理论的第一性原理赝势平面波方法,通过对比分析了不同的Cr微合金化浓度x(x=0~1.0%,原子百分比,下同)对B2-NiAl Cauchy压力参数、晶体弹性常数C44、剪切模量G及G/B0比值、弹性模量E的影响。微观电子能态密度分析结果表明:Cr原子取代Ni原子位或取代Al原子位,均能显著提升纯净NiAl晶体材料的剪切模量G和弹性模量E,但不利于其延性的提高;同时发现,Cr原子与晶体中的点缺陷结构协同作用下能提升晶体的延性,并以Cr原子取代Ni反位结构中的Al位,且合金化浓度x=0.9%,效果尤为明显。

Based on virtual crystal potential function(VCA)approximation,this paper uses the first-principle pseudopotential plane wave method of density functional theory to comparatively analyze impacts of different Cr microalloying concentrations x(x=0—1.0%,atomic percentage,the same below)on B2-NiAl Cauchy pressure parameter,and crystal elastic constant C44,shear modulus G and G/B0 ratio,elastic modulus E.The results of micro-electron energy density analysis indicate that the shear modulus G and elastic modulus E of pure NiAl crystal material can be significantly improved by Cr atom replacing Ni atom or Al atom,but it′s not conducive to improve its ductility.It is found that the synergistic effect of Cr atoms and the point defect structure in the crystal can improve the ductility of the crystal,and the Al site in the Ni inversion structure is replaced by Cr atoms,and the alloying concentration x=0.9%,the effect is particularly obvious.