Wettability of Au-Ag-Si brazing filler metal series with Ni

Based on the phase diagram,three kinds of Au-Ag-Si brazing filler metal with three different constituents,i.e., Au-10.22Ag-3.25Si,Au-14.02Ag-3.28Si and Au-18.47Ag-3.27Si were prepared by using the vacuum melting method in a medium-frequency induction furnace.The spreading-out experiment of the Au-Ag-Si brazing filler metal on Ni sheet was done at 20,40 and 60℃above its liquidus temperature respectively with flow H2 as protective gas.The wettability of the Au-Ag-Si brazing filler metal with Ni was studied by measuring and analyzing the area-of-spread and wetting angle.The interface structure of the brazing filler metal with Ni after its spreading was observed by backscattered electron images.The results show that the Au-Ag-Si brazing filler metal series have a good wettability with Ni.When brazing temperature increases,the area-of-spread increases and the wetting angle decreases,there are wetting rings when brazing filter metal is wetted with Ni.The wetting rings principlely consist of Au element.The intermetallic of Ni3Si is formed at the interface,and the formation of Ni3Si can improve the brazed joint strength to some degree.