Evaluating elastic properties of a body-centered cubic NbHfZrTi high-entropy alloy – A direct comparison between experiments and ab initio calculations

• Published in: Intermetallics 2019-06, Vol.109, p.167-173
• Main Authors: Ye, Y.X., Musico, B.L., Lu, Z.Z., Xu, L.B., Lei, Z.F., Keppens, V., Xu, H.X., Nieh, T.G.
• Format: Article
• Language: English
• Subjects: Bulk density; Bulk modulus; Density functional theory; Elastic anisotropy; Elastic properties; High entropy alloys; High-entropy alloy; Lower bounds; Mathematical analysis; Modulus of elasticity; Poisson's ratio; Resonant ultrasound spectroscopy (RUS); Shear modulus; Specific heat
• ISSN: 0966-9795; 1879-0216
• DOI: 10.1016/j.intermet.2019.04.003

In this study, elastic constants of the equiatomic body-centered cubic NbHfZrTi high-entropy alloy (HEA) were experimentally evaluated using resonant ultrasound spectroscopy and compared directly with calculations based on density functional theory. Elastic properties, including Young's modulus, shear modulus, bulk modulus, Poisson's ratio, and Debye temperature, of polycrystalline aggregates were obtained from measurements and calculations, and excellent agreement was found between the experimental and theoretical data. We also made efforts to employ the rule-of-mixtures (ROM) to predict the elastic moduli of the current alloy, as well as other HEAs reported in the literature, and found that the lower-bound prediction provided a reasonable estimate of the elastic moduli of single-phase HEAs. •Elastic constants of NbHfZrTi alloy were experimentally determined via RUS and theoretically evaluated via DFT.•Polycrystalline elastic properties (E, G, B, v, and ΘD) were subsequently deduced.•Elastic anisotropy is visualized and is correlated with electronic configurations.•Rule-of-mixtures with the lower-bond approach is an appropriate method to estimate elastic moduli of HEAs.