Microstructure and phase constitution near the interface of Cu/Al vacuum brazing using Al–Si filler metal

Brazing of Cu to Al using Al–Si filler metal has been carried out by vacuum brazing technology. The microstructure and the phase constitution in Cu/Al joint were studied by means of metallography, electron probe microanalyser (EPMA) and X-ray diffraction (XRD). Experimental results obtained showed that two kinds of intermetallic compounds (IMCs) are formed near the interface of copper and brazing seam region and those are Cu3Al2 and CuAl2 phases. Moreover, ε-Cu15Si4, Al–Si and CuZn2 are formed on the α-Al solid solution in the brazing seam region. Technology parameters of vacuum brazing were: brazing temperature T=590–610 °C, vacuum level 10−3 Pa, holding time t=5–10 min.