Laser direct joining of AZ91D thixomolded Mg alloy and amorphous polyethylene terephthalate

Lap joints between AZ91D thixomolded Mg alloy and amorphous polyethylene terephthalate (PET) were produced by direct irradiation of high power diode laser beam from either plastic or metal side. Joints with strength higher than that of PET could be successfully produced. Joining mechanism involves the generation of gas bubbles in a narrow region inside PET specimen adjacent to the interface. The pressure induced by expansion of these bubbles secures tight bonding in the micro size between AZ91D and PET specimens. Discrete bubbles morphology associated with metal-side laser-irradiation promoted higher joint strength in comparison with networked wormhole morphology in the case of plastic-side laser-irradiation. The presence of pre-made pits on the AZ91D specimen surface proved to be effective to the improvement in the performance of plastic-side laser-irradiated joints.