Enhanced stress concentration sensitivity of SiCp/Al composite with network architecture

Abstract

For network architecture design, stress concentration sensitivity caused by particle shape may change, which is rarely studied. Here, the particle shape dependent stress concentration and its effect on the deformation, fracture, and mechanical properties were investigated. Three particle shapes including hexahedron, twenty-six face polyhedron, and sphere were utilized to generate different stress distribution states in the matrix. A numerical composite model showing network architecture (like grain boundary) was applied. A strong correlation between particle shape, stress concentration factor ( R SiC), and mechanical properties of network composite was built. The particle shape affected the load-bearing capability due to the stress concentration state generated at particle edges. Near the yield point, hexahedron particle wall parallel to the load direction (PaW) was more effective in carrying loads (∼1000 MPa) than that of twenty-six face polyhedron (750–1000 MPa) and sphere (600–1000 MPa) particles. In network composites reinforced by different shape particles, the main crack always initiated in perpendicular network walls (PeW), but propagated along different paths: in Al matrix for hexahedron particle, along macro-interface of SiC/Al–Al for twenty-six face polyhedron particle, and in PeW for sphere particle. Such crack propagation manners contributed to the different elongations of network composites by various particle shapes: sphere > twenty-six face polyhedron > hexahedron particles. Selection of round particle and adjustment of local volume fraction improved elongation with a sacrifice of modulus and strength.