Abstract: The wettability test and welding quality test were used to study the effects of inhomogeneity of Cu phase on character and brazing performance of different BCu93P copper based brazing filler metal. The results show that BCu93P brazing filler metal is composed with white Cu phase and dark Cu3P phase. The Cu phase is distributed in graininess or unity. The spreadability and clearance fillabitity of brazing filler metal with granular Cu phase are better than that with united Cu phase. BCu93P has good metallurgical combination with the base metal. The weld zone is composed with α-Cu and mix microstructure of α-Cu and Cu3P. The homogeneity of mix microstructure of weld zone brazed by filler metal with granular Cu phase is better than that with united Cu phase, and the size of α-Cu phase of the former is less than the latter. α-Cu phase is the ‘softer’ phase in the weld zone, the united distribution and large size of which go against the improvement of strength of weld zone.

Key words: Copper based brazing filler metal, Inhomogeneity of microstructure, Wettability, Brazing performance