Elastic–Plastic Fracture Toughness of Wrought Dual-Phase Non-equiatomic High-Entropy Alloy (HEA) for Structural Applications

A non-equiatomic dual-phase metastable high-entropy alloy (HEA), Fe 50 Mn 30 Co 10 Cr 10, with FCC-to-HCP transformation has attracted attention due to its excellent combination of high strength and ductility. The present work is focussed on determining the fracture toughness of this alloy using a crack tip opening displacement (CTOD) test method. While fracture toughness of single-phase metastable FCC HEAs and non-equiatomic metastable HEA showing FCC-to-BCC transformation have been investigated, the fracture toughness characterization of a dual-phase, metastable, HEA exhibiting FCC-to-HCP transformation has not been conducted. In this study, the damage-tolerance properties at room temperature, viz., strength (UTS ~ 800 MPa), ductility (total elongation at fracture, 50%), and an elastic–plastic fracture toughness (K JIc value, 205 MPa √m), have been determined. Fractography performed on the fractured CTOD test sample revealed ductile mode of fracture. Oxide inclusion particles in the size range of 2–4.2 μm were found to be uniformly distributed.