Analysis of exposed particles and mechanical performance of brazing joints of SiC_p/2024Al composites

The effect of brazing parameters on the vacuum-brazing microstructure and mechanical performance of SiC_p/2014Al aluminum matrix composite(MMC) was studied.The SiC reinforcements on the parent composite surface were exposed by the surface reinforcement exposing technique,and then Cu was deposited on the parent matrix composite.By using M6 aluminum alloy as the filler metal,the parent composites were brazed under several different parameters.The test results show that if the brazing temperature is lower or the keeping time is shorter,there is Cu retained on MMC surface.With the increasing of brazing parameters(brazing temperature and keeping time),Cu reacts with Al base metal completely.If the brazing parameters are too high,the porosities by over-burning appear in the base metal.X-ray diffractometry analysis indicates that there is no Al₄C₃ brittle phase formed in the brazing joint.The tensile test indicates that the strength of the joint is 202 MPa at brazing temperature 620℃ and keeping time 20 min.The fractography of the brazing joint indicates that the filler metal is un-wetting to the parent composite,the porosities in the parent composite and the aggregated particles in the parent composite are the reasons for the joint cracking.