理论研究VTiTaNbAl_x高熵合金的结构与弹性力学性质

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.

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

Experiments indicated that the VTiTaNbAlx high-entropy alloys (HEAs) adopt a single solid-solution phase having 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 VTiTaNbAlx HEAs. The detailed investigations of atomic radius of alloying elements imply the single phase solid solution for VTiTaNbAlx HEAs. Ab initio calculations predict that the present HEAs have good ductility and VTiTaNb is nearly elastically isotropy. With increasing Al content, VTiTaNbAlx become more anisotropic. The Al content has almost no effect on the polycrystalline elastic moduli of VTiTaNbAlx HEAs. Meanwhile we discussed the Debye temperature of the present HEAs, derived from the elastic constant calculations.