Strength and microstructure of Cu joints brazed with Cu-P based amorphous filler metal contained Zr

The copper joints were brazed with CuP 7.7 Sn5.4Ni14Si0.2Zr0.04 amorphous filler metal and conventional filler metal. The microstructures of filler metal and brazing joints were analyzed and the effect of brazing procedures on joints strength was studied. The results indicate that brazing procedures affect the strength of the brazing joints with both the CuP7.7Sn 5.4 Ni14Si0.2Zr0.04 amorphous filler metal and conventional filler metal. Compared to the amorphous brazing filler metal, conventional filler metal was more sensitive to the brazing procedure. In the same experimental conditions, shear strength of the joint brazed with amorphous brazing filler metal increased by 30% or more compared to the joint which brazed with conventional filler metal. CuP7.7Sn5.4Ni14Si0.2Zr0.04 amorphous brazing filler metal has no obvious phase structures in microscope, while the microstructure of conventional filler metal is mainly composed of primary (Cu,Ni)₃P and (α-Cu+Cu₃P) eutectic and (α-Cu+Cu₃P +δ) ternary eutectic. The microstructure of diffusion and interface zone in joint brazed with CuP7.7Sn5.4Ni14Si0.2Zr0.04 amorphous brazing filler metal are mainly composed of α-Cu solid solution, and the center in the brazing seam is mainly composed of α-Cu and (Cu,Ni) ₃P and (α-Cu+Cu ₃P) eutectic and (α-Cu+Cu₃P +δ) ternary eutectic.