FIRST-PRINCIPLES STUDY OF THE STABILITY OF CoCrFe40-xMnxNi (x = 5, 10, 15, 20) HIGH-ENTROPY ALLOYS

10.25712/ASTU.1811-1416.2023.04.010

Abstract

In this work, a first-principles study of the stability of four alloys with different Fe and Mn contents CoCrFe_40-xMn_xNi (x = 5, 10, 15, 20 at. %) has been carried out. For each composition, special quasi-random structures were created, having the structure type of face-centered cubic lattice and consisting of 32 atoms. Full relaxation of the obtained superstructures and determination of the total ground state energy at 0 K temperature were carried out in the QUANTUM ESPRESSO program complex. Based on the obtained results, the enthalpies of mixing are calculated and it is shown that FCC solid solutions are thermodynamically stable structures for the studied alloys at a given temperature. The lowest value of enthalpy of mixing has the superstructure Co–Cr–Fe–Mn–Ni, which confirms the concept that high-entropy alloys with equiatomic composition demonstrate the greatest stability compared to non-equiatomic alloys. The values of lattice parameters were obtained, which provide the preservation of cubic structure after complete relaxation of the studied structures. The values of density and volume of the fully relaxed superstructures were also calculated, indicating that with increasing Fe content and simultaneous decrease in Mn content, the volume of the superstructures decreases and their density, respectively, increases.