Process–Structure–Property Correlations in Nitrogen-Driven Cold Spray of Cu and Cu–5Ag Coatings

High-pressure cold spray using nitrogen (N₂) as a cost-effective alternative to helium offers significant potential for scalable deposition of conductive materials; however, its influence on process–structure–property relationships in Cu-based systems remains insufficiently understood. In this work, pure Cu and Cu–5 wt.% Ag (Cu–5Ag) coatings were deposited to systematically investigate the role of alloy composition on deformation behaviour, bonding mechanisms, and resulting properties. The deposition conditions enabled high particle velocities, promoting severe plastic deformation, interfacial jetting, and intimate particle–particle contact, which collectively resulted in dense coatings with strong metallurgical bonding. The as-deposited Cu coatings exhibited pronounced strain hardening associated with microstructural refinement, while the Cu–5Ag coatings showed enhanced hardness due to the presence of Ag in solid-solution, accompanied by a reduction in electrical conductivity, highlighting the inherent strength–conductivity trade-off. Post-deposition heat treatment was employed to further tailor the microstructure and properties. The results demonstrate that appropriate thermal exposure facilitates recovery processes and improved interparticle bonding, leading to a reduction in hardness and partial restoration of electrical conductivity. These findings demonstrate that high-pressure, nitrogen-driven cold spray can engineer Cu-based coatings with tunable functional and mechanical properties, offering a promising pathway for the solid-state additive manufacturing of advanced conductive components.