Microstructure and strength of aluminum and aluminum alloy joint brazed with rapidly-cooled Al -Si -Cu-Zn filler metals

The microstructure and strength of aluminum and 6063 aluminum alloy joints brazed with Al70Si7.5Cu20Zn2.5 and Al65Si10Cu20Zn5 rapidly-cooled filler metals were studied.The result indicates that the brazed joint is composed of base metal, center of brazing seam and interface region.The microstructure of interface is α Al solid solutions, while the center of brazing seam is α Al solid solutions, Si and θ(Al₂Cu).The resnlt also indrcates that the strrength of the joint brazed with Al65Si10Cu20Zn5 is higher that the one brazed with Al70Si 7.5Cu20Zn2.5, and the strength of the joint using chloride flux is hgher that the one usding fluoried flux.Under the same technological conditions, shear strength of aluminum joint brazed with rapidly cooled fillers is better than the one of conventional fillers, which increased about 40%.