Microstructure and mechanical properties of high-pressure sintered Al2O3/SiC nanocomposites

Al2O3/SiC nanocomposites were synthesized by high-pressure sintering using α-Al2O3 and β-SiC nanopowders as the raw materials. Microstructure and mechanical properties of the sintered samples were investigated using X-ray diffraction (XRD), Scanning Electron Microscope (SEM), Atomic Force Microscope (AFM) et al. The results indicate that high-pressure sintering is an effective sintering technique, which can densify Al2O3/SiC nanocomposites at high pressure (4.5 GPa) and relatively low temperature (1000-1230 °C). Rapid grain growth of Al2O3 is mainly restrained by the separation effect of nanosized SiC grains. Grain boundary, grain boundary-intragranular and nano-nano structured Al2O3/SiC nanocomposites can be achieved by controlling the sintering temperature and β-SiC content. The highly densified Al2O3/SiC nanocomposite (AS5-1170) exhibits excellent mechanical properties as 429.9 GPa in elastic modulus and 30.7 GPa in nano-hardness.