From Powder Microstructure Engineering to Coating Perfection in Cold Spray Additive

In cold spray additive manufacturing (CSAM), powder is not merely a feedstock but the primary determinant of coating integrity and performance due to the solid-state nature of particle deposition. This work establishes a process–structure–property (PSP) framework by emphasizing powder-centric design for heat treatable Al alloy systems. Advanced powder engineering strategies were implemented through post–gas atomization heat treatments tailored for CSAM. These treatments, including annealing, solution treatment at 500 °C for 15 and 30 minutes, and quenching, were employed to modify powder microstructure, reduce dislocation density, homogenize solute distribution, and enhance deformability. The engineered powders were subsequently deposited via CSAM and benchmarked against as received Al alloy powders. The microhardness and microstructure of both powders and coatings, before and after treatment, were systematically evaluated. Results demonstrate that powder microstructure pre-conditioning governs deformation during high-velocity impact, leading to improved deposition efficiency, enhanced metallurgical bonding, and reduced porosity. Post-spray heat treatment and subsequent aging of the coatings resulted in microstructures comparable to those of bulk Al alloys. Overall, this work demonstrates that powder characteristics are critical in achieving coating perfection, redefining the role of feedstock in next-generation additive manufacturing technologies.