Professor, University of Maryland, College Park, MD
In all cases of discontinuous silicon carbide (SiC/Al) metal matrix it was shown that classical composite strengthening mechanisms could not be used to explain the data. A high dislocation density model was proposed to account for the strengthening, but other factors, such as residual stress and texture, could contribute. These were investigated, and it was shown that texture had no effect and residual stress reduced the tensile yield stress. The fracture process in the composites is controlled by fracture of the matrix up to SiC particle sizes of 20 μm and for larger SiC size particles fracture of SiC begins to dominate. The fracture process in the matrix is influenced by residual hydrostatic tension and high density of dislocations generated at SiC/Al interfaces. Crack initiation fracture toughness does not depend on SiC particle size, for particle sizes less than 20 μm. Crack growth resistance increases as the size of the SiC particles increases.
Paper ID: CTR10276J