Surface-activation assisted brazing of Al-Zn-Mg-Cu alloy: Improvement in microstructure and mechanical properties

The surface oxide film has adverse effect on the brazing of aluminum alloy. In this work, the novel method of surface activation was proposed to remove the surface oxide film of aluminum alloy and promote the atomic diffusion, which improved the microstructure and mechanical properties of brazed joints. Through surface activation process, the surface oxide film was eliminated effectively. The content of grain boundary and the surface dislocation density of the aluminum alloy were increased. The atomic diffusion in brazed joints with surface activation was observed evidently and residual oxide film was removed. The microstructure and shear strength of brazed joint were improved by surface activation, which formed the sound brazed joints.