Mechanical properties of CrFeCoNiCu: X(0 ≤ x ≤ 0.3) HEAs from first-principles calculations

Abstract

Frist-principles calculations combined with exact muffin-tin orbitals (EMTO) and coherent potential approximation (CPA) methods are conducted to investigate the effects of Cu content on mechanical properties of CrFeCoNiCux (0 ≤ x ≤ 0.3) high-entropy alloys (HEAs), and the dependencies of relevant physical parameters on Cu content in HEAs are shown and discussed in this work. It is found that the equilibrium lattice constant increases linearly and the elastic constant decreases gradually with increasing Cu content, and the crystal structure of CrFeCoNiCux (0 ≤ x ≤ 0.3) HEAs can preserve mechanical stability according to the stability criterion of cubic crystals. From the general trend, adding Cu atoms to CrFeCoNi-based HEAs will reduce elastic moduli, Vickers hardness, and yield strength, whereas ductility and plasticity of HEAs show the opposite trend. Also, three different dislocations, including screw, edge, and mixed dislocations, and twins are more likely to occur in HEAs with high Cu content because energy factors decrease steadily and dislocation widths increase gradually with increasing Cu content. The present results provide valuable theoretical verification for further research on the mechanical properties of CrFeCoNiCux (0 ≤ x ≤ 0.3) HEAs.