Abstract:Achieving an optimal strength-ductility synergy efficiently is a critical objective for advanced structural materials. This study developed a novel grain structure in a NiCo-based superalloy, consisting of residual deformed grains, fine recrystallized grains, and multi-scale L12-γ′ precipitates, using a short-term annealing and aging treatment. Compared to the conventional heat-treated condition (yield strength: 1,106 MPa; elongation: 18.8%), the alloy with a partially recrystallized microstructure exhibited a significantly higher yield strength of 1,371 MPa, while maintaining a ductility of 13.3%. This high strength is attributed to synergistic effects from dislocation strengthening (induced by prior cold rolling), fine grain strengthening, and precipitation reinforcement by γ′ phases. In contrast, the fully recrystallized variant demonstrated a yield strength of 1,390 MPa with an elongation of 14.3%, primarily due to a uniform fine-grained structure and homogeneous γ′ precipitation. The underlying deformation mechanisms were thoroughly investigated, re-vealing that dislocation activity, nano-twins, and L-C locks, in addition to the precipitates, are critical for the outstanding mechanical properties. This work provides a practical and cost-effective processing strategy for developing high-performance NiCo-based superalloys for demanding engineering applications.