Co-design of grain heterogeneity and precipitate hierarchy for strength-ductility-conductivity synergy in a conductive Cu alloy

In this work, a coupled multiscale microstructural design strategy was developed for a Cu-5Ni-0.7Si-0.4Al alloy by integrating partial recrystallization-induced grain heterogeneity with hierarchical precipitation. Partial recrystallization produced heterogeneous grains spanning the micrometer to submicrometer scale, while Ni-Si–Al alloying promoted a site-dependent precipitate hierarchy, including intergranular δ-Ni2Si, intragranular δ-Ni2Si, and nanosized Ni-Al-enriched precipitates consistent with an L12-ordered structure. The resulting architecture is inferred to regulate dislocation motion and improve strain compatibility during deformation. The optimized alloy achieves a yield strength of 800 MPa, an ultimate tensile strength of 840 MPa, an elongation of 15%, and an electrical conductivity of 38% IACS.