Strengthening mechanism of ceramic particle reinforced bonds by ultrasonic brazing of AlMMCs

Composite materials (55% (volume fraction) SiCp/A356) were brazed with the assisted ultrasonic wave by filling with a Zn-based alloy solder. With different bonding temperatures, two kinds of bonds, which contained 7% and 35% SiC particles, respectively, were fabricated. The results show that the two kinds of bonds have not only different microstructure properties, but also different crack propagation behaviors, which will bring on wide difference in mechanical properties. The shear strength of the bond containing 35% SiC particles is above 244 MPa, which is 84.7% higher than that of the bond containing 7% SiC particles. The reason is that the SiC particles in the composite bonds can effectively suppress the fracture. And the fracture is also effectively delayed by the Al-based solid solution in the composite bonds. Therefore, with appropriate bonding parameters, ultrasonic brazing can make the SiC particles and Al contents increase in the bond, and this distribution will contribute to the enhanced strength of the brazed bonds.