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

Abstract

AbstractA 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.