An experimental study of particle cracking in metal-matrix composites

Particle cracking is one of the key elements in the fracture process of particulate-reinforced metal-matrix composites (MMCs). The first two sections of this dissertation focus on the investigation of the effects of matrix properties and reinforcement size on SiC particle cracking behavior during tensile deformation in Al- and Cu-based MMCs. The third section of this research studied the sputter coating of ceramic reinforcement particles and the effect of this Cu coating on interfacial bonding.The influence of matrix properties and reinforcement size on particle cracking was examined in aluminum and copper matrix composites reinforced with 9 vol pct of either 23, 63, or 142 Coatings applied to the reinforcement phase will change the composition near the interface and may yield the desired interface properties. A technique for uniformly sputter coating ceramic reinforcement particles was developed and used to coat large SiC particles with copper. Although the copper coating did not significantly improve the interfacial bonding in copper matrix composites, the success in coating reinforcement particles suggests that this approach may be useful in other composite systems.