Microstructural evolution, wear resistance, and interfacial bonding mechanism of 6061 aluminum alloy fabricated by laser-assisted cold spray

By employing a cost-effective cold spray process in nitrogen atmosphere combined with in-situ laser assistance, Al6061 deposits are successfully fabricated on ZL114A substrates. The results indicate that with increasing laser power, the deposit's microstructure undergoes a pronounced evolution from a severely plastically deformed structure with a high dislocation density to an equiaxed recrystallized structure with low dislocation density, and eventually to a coarsened grain structure. An optimal laser power window of approximately 5 kW was identified, within which the synergistic effects of plastic rheology and dynamic recrystallization are most prominent, resulting in a uniform, stable microstructure with low dislocation density. Consequently, the deposit exhibits the best overall wear resistance, with a wear rate only 50% that of the substrate. Moreover, the bonding strength between the deposit and the substrate shows a non-monotonic variation with increasing laser power, reaching a peak value of 79 MPa at 3 kW. The evolution of bonding strength is initially dominated by high-energy impact and thermal softening, whereas at higher powers (>4 kW), it becomes primarily governed by the complex coupling between adiabatic rheological behavior and the pre-deposition crater effect.