Effect of gallium on microstructure and properties of Ag-Cu-Zn filler metal

Melting temperature, spreadability, microstructures of silver filler metal with different content of gallium, and the mechanical properties of brazed joints were studied respectively. Results show that adding gallium can decrease the melting temperature, improve the spreadability of the silver filler metal, and the microstructure of the silver filler metal was refined significantly. 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 indicate that the fracture position of two kinds of brazed joints happened on the base metal, except for the lap joint of brass, which shows better mechanical properties of the joints brazed with the silver filler metal bearing gallium; For the lap joint of brass, the tensile strength gradually strengthened with the increasing of gallium content, and the optimum content of Ga cowsing best comprehensive properties of the AgCuZn filler metal is about 3.0%.