Effects of Ga and Ce on the Microstructure and Properties of Cadmium-free Silver Filler Metals

Abstract:

Effects of Ga and Ce additions on the microstructures and mechanical properties of Ag17CuZnSn-xGa-yCe filler metals and brazed joint were investigated by microscopy method and tensile test. The results indicated that the solidus and liquidus temperatures of filler metals decreased with addition of Ga and Ce. And the wettability of filler metals on the brass and stainless steel improved when the content of Ga and Ce are 2 wt. % and 0.15 wt.%. The highest shear strength of brazed joint was 3% higher than the shear strength of the Ag17CuZnSn-2Ga. During brazing process, Ga has a higher diffusion coefficient into stainless steel than that of other elements. A novel Ce₂₀(Ag, Cu)₄₀Sn₄₀ intermetallic phase was found in filler metal when the content of Ce is higher than 0.3 wt.%.