Microstructure and mechanical properties of 6061 Al joints brazed with a low-melting point filler

Two self-designed AlZnSi alloys were utilized to braze 6061Al alloy,the microstructures and mechanical properties of the joints were also studied.The results showed that the improved non-corrosive flux KCsAlF4 could effectively remove the oxide film on 6061 Al surface.Element Si exists as the plate type and needle type in both the filler metal and brazing seams.The needle type phase is much more obvious when the Si content is high,and the brittle phase could induce the stress concentration.However,the higher content of Si and Al is helpful to refine the grain size in the brazing seam.Both of the strength and gas tightness properties of 6061Al brazed joints are satisfactory,and the fracture shows intergranular fracture characterizes.