Variety of microstructure and mechanical properties along the laser impact welded interface

Laser impact welding (LIW) is an attractive technique for thin film dissimilar materials solid-state welding. To understand the mechanism of laser impact welding, the wave character of wavy interfaces, the morphology of intermetallics, the diffusion phenomenon and the hardness along the welding direction were investigated with Scanning Electron Microscopy (SEM), Energy Dispersive Spectrometer (EDS), and nanoindentation, respectively. There is a microstructure and mechanical property gradient not only along the welding direction, but also perpendicular to it. The variety of both microstructure and mechanical properties is the combined result of impact pressure and impact angle. The gradient of the nanoindentation demonstrated the variety of the strengthening mechanism nearby the weld interface. The study provides valuable knowledge for welding process understanding and control.