Microstructure, thermodynamics and compressive properties of AlCrCuNixTi (x=0, 1) high entropy alloys

Two equiatomic high entropy alloys, AlCrCuNixTi ( x = 0, 1), were prepared by an arc furnace. Their microstructure, thermodynamics and compressive properties were investigated in as- cast state. The AlCrCuTi alloy consists of a face centred cubic (fcc) phase, two body centred cubic ( bcc) phases and an Al4Cu9-like phase, while the AlCrCuNiTi alloy contains an fcc phase and two bcc phases. Thermodynamic expressions based on mixing enthalpy matrix facilitate the thermodynamic calculation. The element Cr takes severe segregation during solidification and forms Cr rich phases in both alloys. The addition of Ni to the AlCrCuNiTi alloy inhibits the formation of intermetallic compounds and enhances the yield strength, compressive strength and ultimate strain, but degrades Vickers hardness.