Particle Deformation and Energy Redistribution in Laser-Assisted Cold Spray Deposition of 6061 Aluminum Alloy

This study seeks to elucidate the precise modulation of laser-assisted cold spray (LACS) particle deposition and to provide guidance for optimizing process parameters in LACS. While LACS has been shown to improve coating quality, the underlying roles of laser-induced thermal softening in particle deformation, impact energy redistribution, and interfacial bonding of 6061 Al alloy remain unclear. Here, multiscale finite element simulations and experiments were combined to investigate single-particle impact and coating build-up under different laser powers. The results indicate that laser assistance enhances thermal softening, leading to stronger radial spreading, more pronounced jetting, and a larger bonding interface. The simulations show that laser heating expands the thermal softening zone and shifts impact energy dissipation from the particle to the substrate, thereby reducing elastic rebound and promoting stable deposition. TEM analysis confirms dynamic recrystallization at the particle interface under all conditions, while higher laser power broadens the recrystallized region from approximately 0.7 μm to about 1.5 μm and promotes grain growth without causing additional oxidation. Moreover, coating porosity decreases from 3.1% to 1.0% with increasing laser power, whereas nanohardness decreases from 1.43 GPa to 1.24 GPa due to the increased contribution of thermal softening. Overall, the study demonstrates that the beneficial effect of laser assistance originates from thermally activated interfacial localization and energy redistribution, offering a mechanistic framework for optimizing the deposition of difficult-to-deposit aluminum alloys.