Directly cast fibrous heterostructured FeNi0.9Cr0.5Al0.4 high entropy alloy with low-cost and remarkable tensile properties

As-cast alloys generally require additional processing steps before optimal strength-ductility combinations can be achieved, thereby impeding the progress of manufacturing high-performance metallic products by direct casting. Here we report a novel low-cost FeNi0.9Cr0.5Al0.4 high entropy alloy with unique fibrous heterogeneous solidification microstructure, i.e., fibers-like face-centered-cubic soft phases that are enveloped in nano-sized ordered body-centered-cubic hard shells. This fibrous microstructure is thought to be responsible for the notable mechanical properties, which includes a yield strength of ∼670 MPa and an ultimate tensile strength of ∼1196 MPa, together with a uniform elongation of ∼21.1% at room temperature. Experimental results confirm the suggestion that the combination of a high strength and good ductility can be attributed to the hetero-deformation induced hardening mechanism generated from the soft-fiber and hard-shell interface. The cost-effectiveness of this as-cast FeNi0.9Cr0.5Al0.4 alloy with its unique fibrous structure and outstanding tensile properties renders it an ideal candidate for structural applications.