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

Aluminum 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 degrees 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 mu m 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 when the brazed seam is subjected to high load.