Novel approach of LY12 alloy brazing

The LY12 Al alloy was brazed with the adoption of the improved KF-CsF-AlF3 flux matching Ag-Al-Cu-Zn filler metal. The shear strength of brazed joint could reach 80% of that, of the substrate and the tensile strength of but brazed joint will be 70% of that of the substrate. This was the great progress against the traditional claim that Al alloy reinforced by heat treatment could not be brazed. The experimental results and theoretical analysis had proved that it was the key issue to remove the MgO oxide film below 503°C. The addition of rare earth La was the effective way to obtain better mechanical properties of the filler metal as well as brazed joints.