The influence of electron concentration and mixing enthalpy on the lattice parameter of single-phase solid solutions of high-entropy alloys based on both bcc or fcc phases

Keywords

single-phase high-entropy alloys, electron concentration, hardness, elastic modulus, lattice parameter, mixing enthalpy.

Cite as

Horban V. F. and Krapivka M. O. The influence of electron concentration and mixing enthalpy on the lattice parameter of single-phase solid solutions of high-entropy alloys based on both bcc or fcc phases. Physicochemical Mechanics of Materials. 2026. 62(1), 062-068.

https://doi.org/10.15407/pcmm2026.01.062

Abstract

The analysis of single-phase high-entropy alloys (HEA) based on both bcc or fcc phases shows that the lattice parameter depends on the electron concentration, mixing enthalpy, and distortion. Single-phase HEAs based on the bcc lattice are formed in the electron concentration range from 4.12 to 7.2 el/at. Single-phase HEAs based on the fcc lattice appear when the electron concentration is ≥ 8 el/at. When the electron concentration increases, the change in the lattice parameter for HEAs with bcc or fcc phases is oppo­site. For single-phase HEAs with an bcc phase, an increase in the lattice parameter values decrease, while with a fcc phase it increases. The shift of the mixing enthalpy towards negative values leads to a decrease in the lattice parameter, while an increase in distortion leads to its increase. It is found that in most cases, the determined lattice parameter of single-phase HEAs based on both bcc and fcc phases is greater than that calculated accor­ding to the mixture rule. At the same time, for single-phase HEAs in which a negative value of the mixing enthalpy and a pair with a negative enthalpy of mixing lower than –35 kJ/mol is observed, the determined lattice parameter is smaller than the calculated one. One of the features of single-phase HEAs is the dependence of the elastic modulus on the lattice para­meter based on bcc and fcc phases.

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