Microstructures and mechanical properties of spark plasma sintered Al ₂O₃-Co composites using electroless deposited Al ₂O₃-Co powders

Microstructures and mechanical properties of spark plasma sintered (SPS) Al₂O₃-Co composites were investigated depending on the sintering temperatures (900-1200°C) and cobalt contents (0-12 mass%). The material properties of relative density and fracture toughness increased as the sintering temperature and Co content (up to 12 mass%Co) increased. In the SPSed Al₂O₃-Co composite sintered at 1200°C, maximum values of relative density and fracture toughness about 99.3% and 8.1 MPam ^1/2, respectively were obtained. The fracture morphology of SPSed Al₂O₃-12 mass%Co composite showed a semi-brittle fracture mode due to the homogeneous dispersion of fine-sized Co particles.