Microstructure and mechanical properties of Al20-xCr20+0.5xFe20Co20Ni20+0.5x high entropy alloys

In this paper, a series of Al20-xCr20+0.5xFe20Co20Ni20+0.5x (x = 2, 4.5, 7, 9.5 at.%) HEAs were fabricated by arc-melting, and their microstructures and mechanical properties (tensile properties, hardness and toughness) were investigated. It was found that the HEAs in the present study could form solid solution with FCC, BCC or FCC + BCC structures. With the decrease in Al content and the increase in Cr and Ni contents, the microstructure of the HEAs evolves from single phase with inconspicuous compositional fluctuation to dual phases with significant difference in element concentration. By adjusting the composition to x = 7, the HEA displays lamella structures and exhibits high tensile strength and fracture toughness as compared to the alloys with x = 2 and 4.5. Dendrite structure emerges in the HEA with x = 9.5, which displays good plasticity and impact toughness. The correlation between composition, microstructure and mechanical properties of these alloys is discussed in detail. This study provides a novel approach in search for new non-equimolar HEAs with outstanding comprehensive mechanical properties. (C) 2015 Elsevier B.V. All rights reserved.