Direct-soldering 6061 aluminum alloys with ultrasonic coating

In this study, the authors applied furnace soldering with ultrasonic coating method to solder 6061 aluminum alloy and investigated the effects of both coating time and soldering temperature on its properties. The following results were obtained: firstly, the solder region mainly composed of four kinds of microstructure zones: rich Sn zone, rich-Pb zone, Sn–Pb eutectic phase and rich Al zone. Meanwhile, the microanalysis identified a continuous reaction product at the alumina–solder interface as a rich-Pb zone. Therefore, the joint strength changed with soldering time and soldering temperature. Secondly, the tensile data had significantly greater variability, with values ranging from 13.99 MPa to 24.74 MPa. The highest value was obtained for the samples coated with Sn–Pb–Zn alloy for 45 s. Fractures occurred along the solder–alumina interface for the 6061 aluminum alloy with its surface including hybrid tough fracture of dimple and tear ridge. The interface could initially strip at the rich Bi zone with the effect of shear stress.