First-Principles Calculations for the Enhancement of Mechanical Properties of High-Entropy Alloys by Carbon Elements

Abstract

A series of alloy solid solution models were developed using the SQS modeling method, and the effect of C doping on the phase structure, elastic properties, and electronic structure of the alloys was investigated using a first-principles approach. The results showed that the CuCrWNi (C), CuCrWMo (C), and CuCrWAl (C) alloys all have a single body-centered cubic (BCC) structure. The alloys conformed to the mechanical stability criterion before and after incorporating C. The incorporation of C leads to an increase in the bulk modulus B of the CuCrWNi, CuCrWAl alloy, and the Young's modulus E and shear modulus G of the CuCrWMo, CuCrWAl alloy. In comparison, the shear modulus G and Young's modulus E of CuCrWNi alloy and the bulk modulus B of CuCrWMo alloy show a decreasing tendency. The alloy is ductile before and after the addition of C. The addition of C increased the Poisson's ratio, Pugh ratio, and Cauchy pressure of CuCrWNi alloy and decreased the Poisson's ratio, Pugh ratio, and Cauchy pressure of CuCrWMo and CuCrWAl. This shows that adding C improves the ductility of CuCrWNi and the strength of CuCrWMo and CuCrWAl alloys. By analyzing the electronic structure of the alloys, it was found that the doping of C made the alloy less stable. Adding C makes the high-entropy alloys more conducive and the metallic properties more noticeable. Moreover, the incorporation of C makes the CuCrWNi pseudo-energy gap decrease and the CuCrWMo, and CuCrWAl pseudo-energy gap increase, which may be related to the change in the mechanical properties of the alloy. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.