Hierarchical multi-component heterogeneous microstructure enabling outstanding strength-ductility synergy in a (FeCoNiV)₉₃Al₅Ti₂ high-entropy alloy

Advanced alloys that maintain both high strength and ductility at different service temperatures are crucial for demanding applications in extreme environments. However, achieving high strength and ductility simultaneously at different temperatures remains challenging due to the occurrence of the ductile-brittle transition. In this study, we report a novel (FeCoNiV)₉₃Al₅Ti₂ high-entropy alloy with a hierarchical multi-component heterogeneous microstructure that achieves an exceptional strength-ductility synergy at both 298 and 77 K. Through valence electron concentrations-guided compositional design and optimized thermo-mechanical processing, a complex microstructure comprising an L1₂-B2 dual-phase matrix with reciprocal precipitation and spinodal decomposed B2(1)/B2(2) nanodomains is designed. The alloy exhibits an ultimate tensile strength of ∼1841 MPa with a tensile elongation of ∼23% at 298 K and an ultimate tensile strength of ∼2285 MPa with a tensile elongation of ∼20% at 77 K. These remarkable mechanical properties are attributed to the synergistic activation of the multiple strengthening and deformation mechanisms, including hetero-deformation induced hardening, Orowan-bypass mechanism, stacking faults, Lomer-Cottrell locks, nanotwins, and spinodal hardening.