Effects of trace indium on properties and microstructure of Ag-Cu-Zn filler metal

Melting temperature, spreadability, microstructures of silver filler metal bearing different content of indium, and the mechanical properties of brazed joints were studied respectively.By using copper and brass plates as base metal, brazing with flame method, the mechanical properties of the joints brazed with lap-joint and butt joint were tested and analyzed at the same time.Results show that adding indium can decrease the melting temperature and improve the spreadability of the silver filler metal, and the microstructures of the silver filler metal bearing different content of indium are refined significantly.For the lap-joint of brass, the tensile strength of the joints gradually strengthens, presenting parabolic shape, with the increasing of the element indium;the fractures position of two kinds of brazed joints happens on the base metal, except for the lap-joint of brass, which shows better mechanical properties of the joints brazed with the silver filler metals bearing indium.