Composite materials (55 vol.% SiCp/A356) were brazed by filling with a Zn-based alloy with the assistance of ultrasonic waves. 37 vol.% SiC particles composite bonds were produced and their structural features as well as mechanical properties were obtained. The crack initiation and propagation behavior of the composite bonds were examined using in situ SEM and SEM fractographic observations. The shear strength of the brazed bonds containing ~37 vol.% SiC particles was 37% higher than the 55%SiCp/A356 composites and 48% higher than the un-reinforced bond. There are two mechanisms of crack initiation in metal matrix composite. In the first cracks may initiate at in the eutectic phase in the composite bond. In the second cracks may also initiate due to cracking of the particles.