Influence of dwelling time on interfacial compounds and mechanical properties of aluminum/copper brazing joints

Aluminum and Copper was brazed using Zn-22Al solder with KAlF4-CsAlF4 non-corrosive flux at different dwelling time. The influence of dwelling time on the interfacial microstructure, interfacial elements distribution and mechanical properties of the brazing joints was studied. Results showed that the CuAl₂ interfacial compounds transformed from Lamellar structure to dendritic structure gradually and grew into the brazing seam; CuAl₂ phase transformed from massive structure to strip or foliated structure in the solder layer; the peak of Zn content on the interface of Cu/Solder layer appeared between the AlCu compounds and Cu substrates when dwelling time came to 2 mins, it moved toward the inside of the solder layer if dwelling time extended. Meanwhile, shear strength of Al/Cu brazing joints increased before reducing with the extending of dwelling time.