An initio study of thermodynamic and fracture properties of CrFeCoNiMnx (0≤x≤3) high-entropy alloys

Thermodynamic and fracture properties of CrFeCoNiMnx (0 ≤ x≤3) high-entropy alloys (HEAs) are theoretically investigated by first-principles calculations based on density functional theory and quasi-harmonic Debye model, and the atomic disorder of crystal cell is modeled via special quasi-random structure (SQS) approach. In which, alloying element Mn and temperature are used as control variables, and then relevant parameters, e.g., formation energy, vibrational entropy, specific heat capacity, thermal expansion coefficient, and fracture energy, are calculated and discussed. The results reveal that the crystal structure of alloys is thermodynamic stability due to having negative formation energy, and the addition of Mn is more conducive to the formation of solid solution structure of five-element alloys than that of quaternary alloy in the CrFeCoNiMnx (0 ≤ x≤3) HEAs. Meanwhile, configuration entropy is positively correlated with formation energy, both of them promote the generation of stable single-phase solid solution of HEAs. Thermionic excitation has a greater effect on the electronic entropy of equiatomic HEAs at high temperature. With increasing Mn content, the crystal structure of alloy is more difficult to expand, and the fracture energy of cell is greater in the [100] [010], and [001] directions, indicating that the strength of interatomic bonding increases gradually with the increase of Mn content for CrFeCoNiMnx (0 ≤ x≤3) HEAs. The present results provide a valuable theoretical reference for further study thermodynamic and fracture properties of CrFeCoNiMnx (0 ≤ x≤3) HEAs.