Ab initio study of Al_xMoNbTiV high-entropy alloys

Abstract

The Al(x)MoNbTiV (x = 0-1.5) high-entropy alloys (HEAs) adopt a single solid-solution phase, having the body centered cubic (bcc) crystal structure. Here we employ the ab initio exact muffin-tin orbitals method in combination with the coherent potential approximation to investigate the equilibrium volume, elastic constants, and polycrystalline elastic moduli of Al(x)MoNbTiV HEAs. A comparison between the ab initio and experimental equilibrium volumes demonstrates the validity and accuracy of the present approach. Our results indicate that Al addition decreases the thermodynamic stability of the bcc structure with respect to face-centered cubic and hexagonal close packed lattices. For the elastically isotropic Al(0.4)MoNbTiV HEAs, the valence electron concentration (VEC) is about 4.82, which is slightly different from VEC ∼ 4.72 obtained for the isotropic Gum metals and refractory--HEAs.

Tailoring the physical properties of Ni-based single-phase equiatomic alloys by modifying the chemical complexity

“…Furthermore, calculated transport properties compared well with experimental values142124. In recent years, the CPA calculations have been successfully expanded to the applications in high entropy alloys, with majority of them focused on the structural, mechanical, defect, and magnetic properties252627282930.…”

Modeling the structure and thermodynamics of high-entropy alloys

“…We gave several examples of their application to HEAs and related compounds. Specifically, we discussed the application of the CPA, 14,41,96,100,101,[113][114][115][116][117][118][119] supercell and SQS methods, 38,40,66,[120][121][122][123] empirical pair-and embedded atom-potentials, [124][125][126][127][128][129][130][131] and the Miedema approximation. 6,56,[58][59][60][61][132][133][134] We explained how these may be combined for direct free energy calculation, 65,85,103,135 incorporated into cluster expansions, 69,70,85,88,109,136 used as the basis for computer simulation, [84]…”

“Treasure maps” for magnetic high-entropy-alloys from theory and experiment

“…27 The DLM resembles a random spin configuration with zero averaged magnetization, while allowing the presence of finite local magnetic moments on each lattice site. EMTO-CPA calculations for HEAs have been carried out to investigate, e.g., phase stabilities and bulk properties [28][29][30][31][32][33][34] as well as stacking fault energies. 35,36 For CoCrFeNi based HEAs, Tian et al and Niu et al have shown that bulk properties, e.g., bulk moduli 28 and enthalpies of formation, 34 are in reasonable agreement between CPA and explicit super cell calculations.…”