Microstructure and properties of Ag10CuZnSn-xIn-yCe low silver filler metal

By adding trace elements of In and Ce into Ag10CuZnSn low-silver filler metal, the effects of the combined addition of In and Ce on the solidus and liquidus temperature and spreading performance of low-silver filler metal were studied, and the effects of two alloying elements on the microstructure of Ag10CuZnSn filler metal and the mechanical properties of brazed joint were analyzed. The results showed that the addition of trace elements of In and Ce could significantly reduce the solidus and liquidus temperature of Ag10CuZnSn low-silver filler metal, and also increase the spreading area of Ag10CuZnSn filler metal on T2 copper and 304 stainless steel base metals. When the contents of In and Ce were 1.5% and 0.15% respectively, the spreading areas of the filler metal on T2 copper and 304 stainless steel increased by 21.1% and 35.7% respectively. Besides, the In and Ce elements could refine the microstructure of the filler metals. When the contents of In and Ce elements were 1.5% and 0.15% respectively, the microstructure refinement of Ag10CuZnSn low silver filler metal was the most obvious, and at this time, the shear strength of 304 stainless steel brazed joint also achieved a maximum value of 375 MPa. However, 3% In and 0.5% Ce would form brittle Ag-In-Sn intermetallic compound phase and Sn-Ce rare earth phase in the microstructure of Ag10CuZnSn filler metal, and the shear strength of the brazed joint would be reduced.