Atomic inter-diffusion between Al particle and Ni substrate for metallurgical bonding during cold spraying process

The cold spraying process is characterized by high strain rate deformation. The metallurgical bonding behavior at contact interface and the effect of deformation on it were investigated. The individual Al particle with native Al2O3 oxide layer on its surface was cold sprayed on the Ni substrate without jetting. Only the oxide layer near the edge of Al particle is disrupted, resulting in virgin metal contact. Other areas of the contact interface could hardly be cleaned by extruding the oxide layer with the flattening of Al particle. The bonding behavior in the virgin metal contact area is confirmed to include atomic inter-diffusion as evidenced by the formation of AlNi3 inter-layer. Numerical simulation was performed and illustrates that the generated intermetallic phase is located near the maximum plastic deformation area. The atomic inter-diffusion is attributed to high strain rate deformation and high contact pressure.