<p>A binder-free powder processing method is introduced for the preparation of Al₂O₃ nanoparticle-reinforced AA6061 composite powders intended for cold spray deposition. In this approach, 30&#xa0;nm Al₂O₃ nanoparticles are uniformly laid down onto the surface of micron-sized AA6061 powder particles through natural electrostatic attraction, eliminating the need for any organic binders or dispersants. With only 1 wt.% nanoparticle addition, a network of nanoceramic particles is formed on the metal particle’s surface, producing a composite feedstock that retains the flowability and deposition characteristics of pure AA6061 powder. The decorated powders were successfully employed as feedstock in a low-pressure cold spray process, yielding coatings with embedded Al₂O₃ nanoparticles distributed along splat interfaces. Upon heat treatment at 430&#xa0;°C for one hour, the nanoparticles effectively pinned dislocations and stabilized low-angle grain boundaries inside the splats, thereby suppressing recrystallization and grain growth. As a result, the coated composite exhibited remarkable thermal stability and maintained its hardness more than twice that of the AA6061 coating. The enhanced mechanical properties and microstructural stability are attributed to the synergistic strengthening mechanisms provided by the nanoparticles, including dislocation pinning and Orowan strengthening. These findings establish nanoparticle surface decoration as a simple and scalable approach for producing cold-sprayable metal matrix composite powders that achieve enhanced hardness and thermal stability with minimal ceramic reinforcement.</p> Graphical Abstract <p></p>