Pulsed laser welding of ultra-thin Mg–Li alloy LZ91 with a thickness of 1 mm was conducted to investigate the effects of laser power

duty cycle

and frequency on weld formation

microstructure

and mechanical properties. The results show that fully penetrated welds with good forming consistency can be obtained by pulsed laser welding. The microstructure of the LZ91 welded joint heat-affected zone is coarse α-Mg and β-Li dual phase structure

and numerous short acicular α-Mg phases are distributed in β-Li grains of the weld zone. The increase of laser power has little effect on the phase composition

but leads to an increase in β grain size in both the heat-affected zone and weld zone. The elongation and impact absorbing energy of welded joints decrease with the increase of laser power

whereas the overall changes in tensile strength and hardness are relatively small. The microhardness of the weld zone is the highest

followed by the base metal

while the heat-affected zone has the lowest microhardness.