Sinter Forging as a Tool for Improving the Microstructure and Mechanical Properties of Zirconia Toughened Alumina

Sinter forging experiments are described of zirconia toughened alumina (15 wt% ZrO₂/85 wt% Al₂O₃), starting from composites containing transition (θ-) alumina. Full density (> 99%) was possible within 15 minutes at 1450°C and 40 MPa and resulted in a homogeneous microstructure with an alumina grain size of 0.8 μm and a zirconia grain size of 0.3 μm. Sinter forging gives an increase in strength and fracture toughness by a factor 1.5 - 2 if compared with pressureless sintered powder compacts.