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Thin metal foil joining has wide applications in medical device and microelectronics. In this paper, laser impact welding was implemented to join aluminum foil to titanium sheet. The velocity of Al flyer was measured with photonic Doppler velocimetry. The maximum velocity reached up to 1000 m/s within 0.2 μs. Varied thickness (25–250 μm) Al flyer was successfully welded with Ti target. Weld strength was measured with peel test. Weld area was estimated with resistance measurement method. The effect of laser spot size, flyer thickness, standoff distance on weld strength, weld area, and microstructure was analyzed. The microstructure was studied with scanning electron microscopy (SEM). By comparing the amplitude and wavelength of the waves at the bonding interface, it is suggested that the wave formation was related to the impact velocity. SEM back scattered electron image did not show apparent diffusion across the weld interface. Both twinning and severe plastic deformation were observed at Ti side along the weld interface, which resulted in hardness increase in this region.

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Photonic Doppler velocimetry was applied to compare magnetic pulse welding and vaporizing foil actuator welding against each other in the form of lap joints made of 5000 series aluminum alloy sheets under identical experimental conditions which are: charging energies of the pulse generator, specimen geometry, initial distances between flyer and target plate. Impact velocities resulting from rapidly vaporizing aluminum foils were up to three times higher than those of purely electromagnetically accelerated flyer plates. No magnetic pulse welds were achieved, while every vaporizing foil experiment yielded a strong weld in that failure always occurred in the joining partners instead of in the weld seam during tensile tests. An analytical model to calculate the transient flyer velocity is presented and compared to the measurements. The average deviation between model and experiment is about 11 % with regard to the impact velocity. Hence, the model may be used for the process design of collision welds generated by vaporizing foil actuators.

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