Investigation on Interface Morphology and Mechanical Properties of Three-Layer Laser Impact Welding of Cu/Al/Cu

In this study, laser impact welding technology was applied to fabricate a three-layer Cu/Al/Cu joint. A series of experiments were carried out to investigate the interface morphology and mechanical properties of the welding samples. Results revealed that different morphologies were generated at the upper and lower interfaces. The lower interface morphology transformed from straight to wavy as the collision point moved outward from the center along the radius. With the increase of laser pulse energy, the areas of upper and lower bonding regions expanded. When the laser energy was small, intermetallics and melting zones were absent and slight element diffusion occurred near the upper and lower interfaces. Melting zones occurred at the welding interface when the laser energy increased. Quantitative analysis by energy dispersive spectroscopy found that Al/Cu intermetallics may be produced in the melting region. Nanoindentation hardness test indicated that as the distance from the upper and lower interfaces decreased, the hardness of flyer plate and base plate increased. Two failure modes, that is, fracture failure at the upper and lower bonding interfaces, were observed under different laser energies.