Microstructure and mechanical properties of yttria-stabilized tetragonal zirconia polycrystals containing dispersed TiC particles

The microstructure and mechanical properties of hot-pressed yttria-stabilized tetragonal zirconia polycrystals (Y-TZP) ceramics containing up to 30 vol % TiC particles were studied. Adding TiC particles to Y-TZP improved the bending strength and fracture toughness. With 20 vol % TiC particles the maximum bending strength and fracture toughness reached 1073 ± 30.4 MPa and 14.56 ± 0.25 MPa m^1/2, respectively. The residual tensile stress induced by the thermal expansion difference between ZrO₂ and TiC must have inhibited the tetragonal-monoclinic transformation. The stress-induced phase transformation was therefore not the dominant toughening mechanism. High-densities of dislocations within TiC particles and microcracking were detected by TEM. The improved toughness of the materials is considered to be the result of crack deflection, crack bowing of TiC particles and microcracking toughening of ZrO₂.