Hierarchical microstructure for improved fatigue properties in a eutectic high entropy alloy

Microstructural hierarchy can enable enhanced properties in high entropy alloys. A unique microstructure was observed in 50% cold-rolled and heat-treated eutectic high-entropy alloy (EHEA). Formation of recrystallized FCC grains and B2 precipitates in FCC lamellae with different microstructural length scale constitute the hierarchy in cold-rolled and heat-treated EHEA. Monotonic loading and high cycle fatigue properties of both microstructures were compared. In as-cast microstructure, the fatigue crack originated in FCC lamellae with the formation of persistent slip bands. The B2 precipitates in cold-rolled and heat-treated alloy delayed the crack initiation and improved fatigue properties. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.