First principles exploration of near-equiatomic NiFeCrCo high entropy alloys.

High entropy alloy NiFeCrCo was systematically studied in the range of near-equal atomic concentrations, i.e., 10–40 at.%, by first-principles tools and high throughput calculations. Enthalpy of mixing, lattice parameter ( a 0 ), bulk modulus ( B ), and shear modulus ( G ) were calculated by the exact muffin-tin orbital method combined with coherent potential approximation (EMTO-CPA) for over 2700 compositions of the NiFeCrCo alloy as a single-phase solid solution in paramagnetic state. It was found that certain elements have the most significant influence on each property, namely, Cr on enthalpy of mixing, Co on a 0 , Fe on B , Co on G , and Cr on the ratio of B / G . An equation to predict the enthalpy of mixing by use of binary enthalpy data was evaluated and was found to have a good accuracy with a root-mean-square deviation (RMSD) of 42 meV per formula unit in the prediction. A similar equation to predict bulk modulus with weighted contribution from first–shell interaction is proposed and tested on all alloys. This equation was also found to be accurate with a RMSD of 6 GPa. Finally, it was found that shear moduli of all tested alloys are largely dependent on C 44 , while the concentration of Co has a noticeable control on C 44 . Spin polarized calculations were performed for a select group of alloys with both EMTO-CPA and the Vienna ab-initio Simulation Package (VASP) with special quasi-random structure models for comparison. Good agreement was found between these methods. [ABSTRACT FROM AUTHOR]