Mechanical properties and microstructures of Nano-Al2O3 particles reinforced Al2O3/AlN composite

Nano-Al2O3 particles reinforced Al2O3/AlN ceramic composite with high mechanical properties were fabricated by vacuum hot-pressing sintering at 1600 °C under an applied pressure of 30 MPa for 180 min. Compared with the blank sample, the sample with 20 vol.% Nano-Al2O3 addition had a significant improvement in mechanical properties, and the flexural strength, fracture toughness and relative density reached to 432.65 (±21.67) MPa, 5.26 (±0.89) MPa m1/2 and 99.3 (±0.21)%. It can be seen from the SEM images, EDS analysis and XRD patterns that Nano-Al2O3 particles agglomerate in the boundary to form sub-micron particles and react with AlN at grain boundary to form the solid solution of AlON. Moreover, the relationship of mechanical properties and microstructure transition of composite is illustrated by schematic and Zener's formula.