Optimising Cold Spray Additive Manufacturing: Pressure- Driven Enhancement of Mechanical Performance in Copper Deposits

Cold spray additive manufacturing (CSAM) is a solid-state process capable of producing dense metallic components without melting, making it highly attractive for copper applications requiring both electrical conductivity and mechanical integrity. In this study, the influence of spray pressure at 30 bar, 40 bar, 50 bar and 60 bar on particle velocity, microstructure, and properties of cold-sprayed copper was systematically investigated using a LightSPEE3D system. The cold spray deposits were characterized by X-ray diffraction (XRD), hardness testing, eddy current conductivity, tensile evaluation, and scanning electron microscopy (SEM). The results reveal that increasing spray pressure enhances particle velocities beyond the critical threshold for copper, leading to oxide rupture, improved metallurgical bonding, and microstructural refinement through severe plastic deformation and continuous dynamic recrystallization (cDRX). XRD analysis confirmed progressive grain refinement and increased dislocation density with pressure, which directly correlated with improved ductility. While hardness decreased due to recovery and recrystallization, electrical conductivity increased as porosity and inter-splat boundaries were reduced. Tensile testing showed a clear strength–ductility transition, with deposits at higher pressures exhibiting bulk-like plasticity and fully ductile fracture morphologies. Overall, the findings identify an optimum processing window at higher spray pressures, where copper cold spray deposits achieve a balanced combination of conductivity, ductility, and strength. This study highlights the critical role of spray pressure in controlling the interplay between particle velocity, dynamic recrystallisation, and multifunctional performance in CSAM copper components.