Microstructure and mechanical properties of Al0.5CoCuNiTi high entropy alloy.

A novel 3d transition metal high entropy alloy (3d TM HEA), Al_0.5CoCuNiTi, was prepared by arc-melting. The phase component, microstructure, and mechanical properties in as-cast and annealed conditions were investigated. The results showed the phase structures of the studied alloys in both states were composed of FCC and BCC. The BCC phase was the absolute primary phase with a volume fraction of 84%. The FCC phase corresponded to Cu-rich regions, forming a continuous interdendritic regions wrapping the BCC dendrites. Compared to the majority of the reported single-phase FCC 3d TM HEAs, the alloys under both conditions possessed a promising trade-off in strength and plasticity. Specifically, the yield strength (σ_0.2) was 1130 and 996 MPa for the as-cast and annealed states, respectively. The compressive strain was more than 15% in both states. In the present work, the combination of phase constitution, morphology, and solid-solution strengthening was performed to justify the mechanical behaviour. [ABSTRACT FROM AUTHOR]