Plasma in-situ thermal-assisted cold spray depositing of 7075 aluminum alloys: Microstructure optimization and property enhancement

To address the current challenges of cold-sprayed deposits including high porosity, poor interparticle bonding, and insufficient plasticity, this study employed an in-situ plasma-assisted cold spraying technique to investigate the effects of Ar and He plasmas at different power levels on deposition characteristics. A spatial configuration design between the plasma and cold spray systems was implemented to achieve flexible assistance. The results demonstrate the potential of this method for fabricating high-density, high-performance 7075 aluminum alloy deposits in cold spray additive manufacturing. Plasma-assisted 7075 Al deposits exhibited an order-of-magnitude reduction in porosity (from 2.03 % to 0.14 %) compared to conventional cold spraying, along with significantly improved interfacial bonding quality. The plasma thermal assistance promoted recovery and recrystallization in the deposits, thereby partially restoring their plasticity. With increasing plasma power, the microhardness of deposits increased from 109.7 HV_0.5 to 142.1 HV_0.5, while the friction coefficient decreased from 0.4712 to 0.4139. Furthermore, the wear rate was dramatically reduced by 78.8 %, from 25.91 × 10⁻⁴ mm³·N⁻¹·m⁻¹ to 5.48 × 10⁻⁴ mm³·N⁻¹·m⁻¹, indicating substantial mechanical property enhancement.