Investigation on properties and microstructures of Ag-Cu-Zn-Sn-xGa-yIn filler metal

The effect of Ga and/or In on the microstructures of Ag based filler metals for brazing as well as the properties of the brazed joints have been investigated in this paper. Brazed with brass as the base metal (butt joints), the results showed that, the optimum content of Ga and In in Ag-Cu-Zn-Sn-xGa-yIn filler metal was about 3% and 1.5% respectively, and the mechanical property of the Ag-Cu-Zn-Sn-3Ga-2In filler metal displayed the best value when the Ga and In were added into the filler metal simultaneously. When observing the tensile fracture of the butt joint brazed with Ag-Cu-Zn-Sn-3Ga-2In, it was found that the ductile fracture characteristics, when the content of In exceeded 2%, the dissociation morphology fracture would be emerged which had little influence on the tensile property of the brazed joints. The elements of Ga and In distributed uniformly, no segregation in the microstructure of the Ag-Cu-Zn-Sn-3Ga-2In filler metal was observed by SEM, and the significant 'framework 'structure' was found in the matrix.