Brazing technology of aluminium alloy containing scandium

The feasibility of furnace brazing was investigated for AlZn-Mg-Sc-Zr alloy.The results show that the brazed joint with good appearance can be obtained by choosing the appropriate filler metal and flux and optimizing the brazing parameters.According to the mechanical property tests and the microstructure observation of the joint,the brazed joint has good mechanical properties and a dense microstructure without brazing defects such as pores,inclusion and micro-cracks.Scanning electronic microscopy(SEM) observation of tensile fracture manifests the mechanism of toughness crack.The composition analysis of brazed seam demonstrates that metal elements of filler metal and base metal have diffused into each other,and they are well joined.The analysis of X-ray diffraction(XRD) indicates that there are phases of Al₃Sc,Al₂Zr₃,etc in the joint,which can increase the joint shear strength to some extent.