Short-range order effects on the thermodynamic behavior of AlxCoCrFeNi high-entropy alloys

Abstract

Short-range order (SRO) in high-entropy alloys (HEAs) has been observed both computationally and experimentally in recent studies. Despite their recognized influence on the physical properties of the HEAs reported, a comprehensive work on the relationship between SRO and the tuning of the thermodynamic properties of HEAs has been lacking. In this research, to identify the SRO-property relationship, the Warren-Cowley (WC) parameters, which quantify the degree of SRO, and thermodynamic properties in Al_xCoCrFeNi HEAs were investigated, utilizing the molecular dynamics (MD) simulations, hybrid molecular dynamics/Monte Carlo (MD/MC) simulations, and density functional theory (DFT) calculations. We examined SROs in different phases of Al_xCoCrFeNi HEAs by varying aluminum (Al) contents (x_Al) ranging from 0 to 2.0. Results reveal a prevalent negative SRO of Al-Fe and positive SRO of Al-Al pairs across all HEA cases. Under the influence of SRO parameters, lattice thermal conductivity and bulk modulus exhibit higher values, whereas coefficient of thermal expansion exhibits lower values. This research advances our understanding of the SRO-properties relationship in HEAs, contributing to the design of HEAs with tailored properties through structural tuning.