Study on microstructures and grain boundary penetration behaviours in contact reactive brazing joints of 6063 Al alloy

Abstract

Contact reactive brazing on 6063 Al alloy has been conducted by using Cu foil or Cu foil–Mg powder–Cu foil multilayer as interlayer. The microstructures of the joints and grain boundary penetration phenomenon were analysed and discussed primarily. The results showed that the microstructure of the reaction zone consisted of α-Al solid solution and CuAl₂ compound as monolayer Cu foil was used, and meantime, obvious grain boundary penetration phenomenon at the reaction interface was found. However, the reaction zone of the joint bonded with Cu foil–Mg powder–Cu foil was composed of Al(Mg, Cu) solid solution, CuAl₂ intermetallic compound, Cu–Al–Mg ternary intermetallic compound and Al₂MgO₄. It was also found that the grain boundary penetration phenomenon was delayed as Mg powder was added into the interlayer.