Elasticity of high-entropy alloys from ab initio theory

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Elasticity of high-entropy alloys from ab initio theory Shuo Huanga) Applied Materials Physics, Department of Materials Science and Engineering, Royal Institute of Technology, Stockholm SE-100 44, Sweden

Fuyang Tian Institute for Applied Physics, University of Science and Technology Beijing, Beijing 100083, China; and Beijing Key Laboratory for Magneto-Photoelectrical Composite and Interface Science, University of Science and Technology Beijing, Beijing 100083, China

Levente Vitos Applied Materials Physics, Department of Materials Science and Engineering, Royal Institute of Technology, Stockholm SE-100 44, Sweden; Department of Physics and Astronomy, Division of Materials Theory, Uppsala University, Uppsala SE-75120, Sweden; and Wigner Research Centre for Physics, Institute for Solid State Physics and Optics, Budapest H-1525, Hungary (Received 14 April 2018; accepted 25 June 2018)

High-entropy alloys (HEAs) consisting of multiprincipal elements have demonstrated many interesting structural, physical, and chemical properties for a wide range of applications. This article is a review of the current theoretical research on the elastic parameters of HEAs. The performance of various ab initio-based computational models (effective medium and supercell approaches) is carefully analyzed. Representative theoretical elastic parameters of different HEAs, including single-crystal elastic constants, polycrystalline elastic moduli, elastic anisotropy, and Debye temperature, are presented and discussed. For comparison, simple mixtures of the elastic moduli of pure elements are calculated and contrasted with the ab initio results. The present work provides a reference for future theoretical investigation of the micromechanical properties of systems based on HEAs.

I. INTRODUCTION

High-entropy alloys (HEAs) are a newly emerging class of materials with a distinct alloy design strategy.1,2 Different from the traditional alloys with one or two major elements, HEAs are characterized by their special compositions consisting of multiprincipal elements in equal or near-equal molar ratios. This concept has led to many successful multicomponent materials with interesting physical, chemical, and structural properties, which has attracted increasing attention from the academic and metallurgic research communities.3–14 In previous work, a special crystalline behavior has been discovered, i.e., despite containing multiple components with different crystal structures in their ground states, many HEAs tend to possess a single solid solution phase rather than complex intermetallic structures.15 Generally, HEAs consisting of late 3d transition metals tend to form a face-centered cubic (fcc) phase,16–18 those composed of refractory metals often show a body-centered cubic (bcc) phase,19–22 while HEAs based on rare-earth metals usually a)

Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2018.