Influences of In on the Microstructure and Mechanical Properties of Low Silver Ag-Cu-Zn Filler Metal

Novel low silver based filler metals were developed used for brazing brass and 304 stainless steel. The microstructure of the low silver based filler metals was observed by scanning electron microscopy (SEM) and the wettability was also analyzed. The mechanical properties of lap joint were tested. The brass and stainless steel were brazed with flame method. The results indicate that the microstructure of the metal is composed of Cu base solid solution, Ag base solid solution and CuZn compound. In addition decreases the solidus and liquidus temperatures and improves the wettability of the low silver based filler metals. The tensile strength of joints increases with the addition of indium due to the solution strength effect. The joint of brass and 304 stainless steel by 17AgCuZn-1In exhibits good appearance and dense microstructure with no defects, and its performance is comparable with that of the joint brazed with the B25AgCuZnSn filler metal, suggesting a significant Ag-saving effect.