First principles exploration of near-equiatomic NiFeCrCo high entropy alloys

Abstract

High entropy alloy NiFeCrCo was systematically studied in the range of nearequal 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 singlephase 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-meansquare 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 5.9 : 6 GPa. Finally, it was found

Effect of alloying elements on stacking fault energies and twinnabilities in high‐entropy transition‐metal carbides

“…The phase stabilities of ZrNbTa‐based HETMCs without and with distortion are discussed in terms of formation enthalpies ∆H f calculated as Equation (2): 12 where E tot is the total energy of supercell, N i is the number of atoms in a single cell, and E i is the energy per atom of pure i in the ground state of an elemental solid 12 . Formation enthalpy is used to determine how the formation of a particular phase is more favorable than that of pure stable phases 51 . A negative formation enthalpy implies a thermodynamically stable structure 52,53 .…”

Modeling the structure and thermodynamics of high-entropy alloys

“…We gave several examples of their application to HEAs and related compounds. Specifically, we discussed the application of the CPA, 14,41,96,100,101,[113][114][115][116][117][118][119] supercell and SQS methods, 38,40,66,[120][121][122][123] empirical pair-and embedded atom-potentials, [124][125][126][127][128][129][130][131] and the Miedema approximation. 6,56,[58][59][60][61][132][133][134] We explained how these may be combined for direct free energy calculation, 65,85,103,135 incorporated into cluster expansions, 69,70,85,88,109,136 used as the basis for computer simulation, [84]…”

Microstructures and Properties of High‐Entropy Materials: Modeling, Simulation, and Experiments

“…DFT has been widely applied to study the physical/chemical properties of materials. [ 31–33 ] The derivation of DFT comes from two theorems: [ 34 ] 1) the number density of particles determines the ground‐state energy of the many‐electron system from the Schrödinger's equation; and 2) the ground‐state energy of system is obtained via determining the electron density at the minimum system energy. Thus, the ultimate objective is to obtain the ground‐state energy of a system via the solution of Schrödinger's equation.…”