Effect of Electron Concentration on Phase Composition of High-Entropy Equiatomic Alloys

Abstract

A series of high-entropy equiatomic alloys have been analyzed to determine the main factors that influence the formation of various solid solutions and chemical compounds. It is found out that the key factor leading to the formation of phases in high-entropy equiatomic alloys is mean electron density (e/at.) The necessary condition for the high-entropy σ-phase to emerge is the presence of elements forming it in two-component alloys in various ratios, the electron density of the alloy is to be between 6.7 and 7.3 e/at. The Laves phase shows up in the high-entropy equiatomic alloys at a mean electron density of 6–7 e/at. in the presence of atoms differing by more than 12% in size and having mixing enthalpy lower than –30 kJ/mol. It is revealed that the lattice parameter in bcc high-entropy equiatomic alloys influences their elastic modulus and hardness.