Enhancement of strength-ductility trade-off in a high-entropy alloy through a heterogeneous structure

The improvement in strength is usually accompanied by ductility loss in structural materials, which is a long-standing conflict referred as the strength-ductility trade-off. Here we present a heterogeneous-structures-architecting strategy, in which we design bulk high-entropy alloys with the largely enhanced strength-ductility trade-off, possessing a yield strength of 711 MPa, a tensile strength of 928 MPa, and a uniform elongation of 30.3%. Such an enhancement of the strength-ductility trade-off is due to the microstructure comprised with a combination of the non-recrystallized and recrystallized grains arranged in complex heterogeneous structures with a characteristic dimension spanning from the submicron scale to the coarse-sized scale. The heterogeneous structures in the high-entropy alloy are produced by cold-rolling, followed by intermediate-temperature-annealing. Our results demonstrate that heterogeneous designs can be accomplished effectively by simple thermal treatments, which offer a design strategy towards a new generation of high-strength and high-ductility high-entropy alloys. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.