Mechanical properties and microstructure of Al2O3-TiC-ZrO2 nanocomposites prepared by combustion synthesis-hot pressing

Al2O3-TiC-ZrO2 nanocomposites were fabricated by combustion synthesis-hot pressing with the cheap reactants of TiO2, Al, C and ZrO2. The effects of ZrO2 nano-additives on the mechanical properties and microstructure of Al2O3-TiC ceramic-matrix composites were discussed. With the addition of ZrO2 nanoparticles, the dominant fracture mode of the composites changed from intergranular fracture into transgranular fracture. ZrO2 nanoparticles dispersed mainly in Al2O3 matrix. The residual stresses generated by the thermal expansion coefficient mismatch between ZrO2 particles and Al2O3 matrix induced dislocation and microcracks around the nanoparticles. And the effects of nanoparticles on the deflected propagation, nailing and blocking of the dislocation are remarkable and can be used to explain the improvement of the strength and toughness of Al2O3-TiC-ZrO2 composite. Al2O3-TiC-10ZrO(2) composite exhibits good mechanical properties with the flexural strength of 706 MPa, tile fracture toughness of 6.3 MPa.m(1/2) and the HRA hardness values of 94.4, respectively.