Abstract
The microstructure and mechanical properties of Al2O3/SiC nanocomposites, which were prepared by pressureless-sintering of the nanocomposite powder, were investigated Nanocomposite powders were synthesized by calcination of mixtures of r-A2O3 (aveage paticle size:4nm) and SiC (average particle size:20nm). The particlesof nanocomposite powder had a two-phase structure, SiC contained within Al2O3. Transmission electron microscope observation of pressureless sintered bodies showed that SiC particles were dispersed within the Al2O3 grains and some dislocation lines were observed within the Al2O3 grains. The fracture strength of Al2O3/SiC nanocomposites was higher than that of the Al2O3 monolithic ceramics. At the same time, the fracture mode changed from intergranular to tragranular. After HiPing and annealing of the sintered bodies, the fracture strength increased up to above 1000MPa. It was also observed that the dislocation pile-up increased and the tragranular fracture surface was coarser.
