Uniting ultrahigh tensile strength with ductility in CoCrNi alloy via cross-cryo-rolling

Achieving a simultaneous balance of high strength and ductility remains a persistent challenge in metallic materials. This study presents an outstanding combination of these properties in a multicomponent CoCrNi alloy processed via cross-cryo-rolling. An ultra-high strength of 2.68 GPa is achieved, however, with an initial limited ductility of 2–3 % and a ∼10 % fracture strain at room temperature. Notably, post-rolling heat treatment remarkably elevates tensile ductility to 17 % and fracture strain of ∼27 %, while retaining a 2.1 GPa ultimate tensile strength. These impressive mechanical performances are attributed to the intricate evolution of microstructural defects during cryogenic deformation and subsequent tensile straining. Specifically, the thermo-mechanically induced defect architecture characterized by deformation and annealing twin colonies, stacking faults, retained hexagonal close-packed laths, and discrete dislocation structures evolve into multiple deformation twins, unique stacking faults canals, and Lomer-Cotrell locks. This study unveils a straightforward approach to achieve unprecedented strength-ductility synergy, yielding a CoCrNi alloy with exceptional toughness.