理论研究VTiTaNbAl_x高熵合金的结构与弹性力学性质

Theoretical study of structures and elastic mechanics of VTiTaNbAl_x high-entropy alloys

实验已证明VTiTaNbAl_x高熵合金(HEAs)为单相固溶体,它采用了体心立方结构.在本文中,我们使用基于密度泛函理论的饼模轨道(EMTO)结合相干势近似(CPA)方法,计算并分析了此高熵合金体系的平衡体性质,弹性常数及多晶弹性模量.结果表明:此系列高熵合金符合单相高熵合金的理论判据,具有较好的内在塑性,等摩尔比的VTiTaNb高熵合金趋于弹性各向同性.随着Al含量的增加,此系列高熵合金的弹性各向异性趋于增大,但对多晶弹性模量几乎没有影响;同时讨论了基于弹性常数计算的德拜温度.

Experiments indicated that the VTiTaNbAl_x high-entropy alloys（ HEAs） adopt a single solid-solution phase with the body centered cubic（ bcc） crystal structure.We use the ab initio exact muffin-tin orbitals method（ EMTO） in combination with the coherent potential approximation（ CPA） to investigate the equilibrium volume properties,elastic constants and polycrystalline elastic moduli of VTiTaNbAl_x HEAs.The detailed investigations of atomic radius of alloying elements imply the single phase solid solution for VTiTaNbAl_x HEAs.Ab initio calculations predict that the present HEAs have good ductility and VTi Ta Nb is nearly elastically isotropy.With increasing Al content,VTiTaNbAl_x become more anisotropic.The Al content has almost no effect on the polycrystalline elastic moduli of VTiTaNbAl_x HEAs.Meanwhile we discussed the Debye temperature of the present HEAs,derived from the elastic constant calculations.