3Y-TZP/Al2O3 composites were pressureless sintered with the addition of TiO2-MnO2 and CaO-Al2O3-SiO2 glass. The densification, microstructure and mechanical properties of the composites were investigated. It was found that the composites could be densified at a temperature as low as 1400 degrees C by liquid phase sintering. The majority of the grain sizes for both Al2O3 and ZrO2 were below 1 mu m because of the lower sintering temperature. A bending strength of 934 +/- 28 MPa and fracture toughness of 7.82 +/- 0.19 MPam(1/2) were obtained for 3Y-TZP/Al2O3 (20 vol%) composite. Transformation toughening is considered the responsible toughening mechanism. (C) 2005 Springer Science + Business Media, Inc.