Effects of additives on microstructure and properties of alumina-silicon carbide nanocomposites

Al2O3/5-vol%-SiC nanocomposites have been fabricated by using pressureless sintering with MgO and/or Y2O3 sintering aids and post-hot isostatic pressi ng (HIPing), which circumvents the limitations of hot pressing, Al2O3/SiC n anocomposites that have been doped with 0.1 wt% MgO and 0.1 wt% MgO + 0.1 w t% Y2O3 show an increased sintering density and a homogeneous microstructur e, as well as a high fracture strength (1 GPa) after HIPing. In contrast, u sing Y2O3 as a dopant has a negative impact on the microstructure and the f racture strength. The results suggest that MgO, as a sintering additive, ha s a key role in improving the densification and controlling the microstruct ure of Al2O3/SiC nanocomposites.