Study on properties of single-phase high entropy alloys with FCC structure based on the empirical electron theory

•Empirical electron theory is first used to study single-phase FCC high entropy alloys.•Mechanical and thermal properties of FCC HEAs are influenced by the valence electron structures.•Melting points strongly depend on the covalent electron pair numbers nA. The valence electron structures, thermal properties, hardness and magnetic moments of single-phase high entropy alloys with the face-centered cubic structure have been first investigated with the empirical electron theory of solids and molecules. The theoretical bond lengths agree with the experimental ones well. The calculated melting points of CrFeCoNi, CrMnFeCoNi and CrFeCoNiCu alloys are consistent with their differential thermal analysis (DTA) measured ones. The calculated magnetic moments of ferromagnetic FeCoNi and FeCoNiX0.25 (XAl or Si) alloys agree with the observed ones well. The physical properties of these alloys are strongly associated with their valence electron structures. It is suggested that the melting point, cohesive energy, hardness and magnetic moments of the face-centered cubic high entropy alloys are mainly modulated by bonding factor f, covalent electrons per atom nc/atom, covalence electron pair nA and 3d magnetic electron, respectively.