Stacking faults in SiC particles and their effect on the fracture behavior of a 15 Vol Pct SiC/6061-Al matrix composite

Mechanical tests and microstructural examinations performed on a SiC-particle-reinforced 6061-Al matrix composite indicate that particle cracking during mechanical testing significantly affects the failure mechanisms of the composite. Microcracks were observed to nucleate and propagate on stacking faults and interfaces between the 4H (or 3C) and 6H hexagonal phases within the SiC particle reinforcements. These planar Refects were the predominant defects seen in the SiC particles. Partial dislocations, having a 1/3 〈101̄0〉 Burgers vector, were also observed bounding the stacking faults in the reinforcement phase.