O-induced ultra-strong and deformable oxide/nanocrystalline dual-phase structure in CoCrFeNiMn high entropy alloys

Achieving synergy between ultra-high strength and plasticity in nanocrystalline metals remains a grand challenge, as they are typically plagued by intrinsic brittleness arising from catastrophic shear localization. Here, we overcome this limitation by engineering an oxide/nanocrystalline dual-phase (ONDP) architecture within a CoCrFeNiMn high-entropy alloy via rapid current-activated sintering. Guided by atomistic simulations and lattice misfit calculations, a high density of semi-coherent C15-Cr 2 MnO 4 nanoprecipitates was successfully introduced via an ethylene glycol-assisted ball milling and sintering process. The fabricated alloy delivers a compressive yield strength of 4.5 GPa, which is among the highest values reported for nanocrystalline fcc metals/alloys tested by micropillar compression, while maintaining >30% uniform plasticity. Mechanistically, these semi-coherent oxides effectively suppress grain rotation and convert the nanocrystalline matrix into dislocation storage reservoirs, thereby avoiding strain localization and enabling pronounced strain hardening. This study establishes a scalable pathway for stabilizing nanostructures through O-induced dual-phase engineering, offering a blueprint for next-generation high-performance structural materials.