Atomic Diffusion Behavior and Interface Waveform on the Laser Shock Welding of Aluminum to Nickel

Atomic diffusion behavior and interface waveform characteristics and formation mechanism during laser shock welding were investigated by using a molecular dynamics (MD) model and smooth particle hydrodynamics (SPH) modeling. The MD simulation showed that the diffusion coefficient of Al atom was larger than that of the Ni atom. Ni atom is easily diffused deeply into the Al lattice during impact welding. The SPH simulation showed that the wavelength and amplitude of the welding interface increased with loading speed, and SPH simulations at different loading speeds demonstrated that the movement direction of the Ni wave peak is the same as the welding direction, whereas the movement direction of the Al wave peak is opposite to the welding direction. The effective plastic strain and temperature were mainly distributed at the interface waveform. The shear stress of the composite and substrate foil is in opposite direction near the collision point, and the pressure near the collision point was as high as about 10 GPa. Energy-dispersive spectroscopy line scanning analysis showed the presence of a 2.5-μm-thick element diffusion layer at the wavy interface between Al and Ni, verifying the element diffusion between Al and Ni in the MD simulation.