Research on reaction brazing of Ti layer-coated SiCp/Al composites using Al-based filler metal foil

ABSTRACTAluminum metal matrix composites with high SiC particle content (SiCp/Al MMCs) was surface metalized with Ti layer by magnetron sputtering technology, and reaction brazing was performed on it by using rapidly cooled Al-12Si-5Mg (wt.%) foil as filler metal. Microstructures and properties of the brazed joints were observed and discussed by secondary electron imaging and shearing test, respectively. The bonding mechanisms of SiC particle/Ti coating layer/filler interfaces were analyzed by the thermodynamic method and energy-dispersive X-ray spectroscopy analysis. Results show that void-free joint is obtained at 575°C for a soaking time of 30 min, and it achieves a shear strength of 106.4 MPa. In the brazed seam, continuous Mg-O-rich layer (~1 μm thick) indicates that Mg promotes wetting in progress, and 45.54Ti-15.01Al-39.45Si (wt.%) intermetallic layer shows reaction brazing occurred by active Ti action. However, fracture is prior to occur in the intermetallic layer because of its high briteness whe...