First-principles calculations of structural, elastic and electronic properties of (TaNb) 0.67 (HfZrTi) 0.33 high-entropy
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First-principles calculations of structural, elastic and electronic properties of (TaNb)0.67(HfZrTi)0.33 high-entropy alloy under high pressure Zhi-sheng Nong 1), Hao-yu Wang 1), and Jing-chuan Zhu 2) 1) School of Materials Science and Engineering, Shenyang Aerospace University, Shenyang 110136, China 2) School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China (Received: 3 January 2020; revised: 23 April 2020; accepted: 11 May 2020)
Abstract: To clarify the effect of pressure on a (TaNb)0.67(HfZrTi)0.33 alloy composed of a solid solution with a single body-centered-cubic crystal structure, we used first-principles calculations to theoretically investigate the structural, elastic, and electronic properties of this alloy at different pressures. The results show that the calculated equilibrium lattice parameters are consistent with the experimental results, and that the normalized structural parameters of lattice constants and volume decrease whereas the total enthalpy difference ΔE and elastic constants increase with increasing pressure. The (TaNb)0.67(HfZrTi)0.33 alloy exhibits mechanical stability at high pressures lower than 400 GPa. At high pressure, the bulk modulus B shows larger values than the shear modulus G, and the alloy exhibits an obvious anisotropic feature at pressures ranging from 30 to 70 GPa. Our analysis of the electronic structures reveals that the atomic orbitals are occupied by the electrons change due to the compression of the crystal lattices under the effect of high pressure, which results in a decrease in the total density of states and a wider electron energy level. This factor is favorable for zero resistance. Keywords: first-principles calculations; elastic property; electronic structure; density of states; high-entropy alloys; high pressure
1. Introduction Traditional alloys, such as steel, aluminum, and magnesium alloys, are generally composed of one or two major metal elements, to which other constituent elements are added to modify the properties. In 2004, a new alloy design strategy was proposed by Yeh et al. [1] and Cantor et al. [2], which yields high-entropy alloys (HEAs). These novel alloys typically comprise five or more elements, each of which accounts for between 5at% and 35at%. Because of their unique “four core effects,” HEAs generally exhibit excellent properties such as high strength, high hardness, and good erosion and corrosion resistances [3–6]. To date, research on HEA systems divides HEAs into two main types. One is the traditional HEA, which is composed of alloying elements in the first Ⅳ cycle, such as the most widely studied alloy AlCrFeCoNi. The effect of a high strain rate on Al0.1CrFeCoNi HEA was investigated by Kumar et al. [7], who found that the formation of twin structures was related to the strain rate, with a secondary twin phase generated at high temperature. The effect of Nb content on AlCoCrFeNi HEA, as studied by Ma and Zhang [8], indicated that the structures of AlCoCrFeNi
were
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