Effect of gallium addition on microstructure and properties of Ag-Cu-Zn-Sn alloys

The effects of Ga on microstructures and mechanical properties of the cadmium-free silver based brazing filler metals have been investigated. The results indicated that Ga additions had the noticeable effect on the microstructure, especially on the shape of the phases. With the increase of Ga addition, the amount of eutectic structure increased, and the acicular eutectic structure changed into the fine eutectic structure with micro-vermiform and rod-like shape. When the addition of Ga was 3.0 wt.%, none of defects exist in the microstructure of the brazed joint. The tensile strength increased from 382 MPa to 511 MPa with the content of Ga increasing from 0 to 3.0 wt.%.