Mechanical Properties of an Extremely Tough 1.5 mol% Yttria-Stabilized Zirconia Material

Yttria-stabilized zirconia (Y-TZP) ceramics with a drastically reduced yttria content have been introduced by different manufacturers, aiming at improving the damage tolerance of ceramic components. In this study, an alumina-doped 1.5Y-TZP was axially pressed, pressureless sintered in air at 1250–1400 °C for 2 h and characterized with respect to mechanical properties, microstructure, and phase composition. The material exhibits a combination of a high strength of 1000 MPa and a high toughness of 8.5–10 MPa√m. The measured fracture toughness is, however, extremely dependent on the measurement protocol. Direct crack length measurements overestimate toughness due to trapping effects. The initially purely tetragonal material has a high transformability of >80%, the transformation behavior is predominantly dilational, and the measured R-curve-related toughness increments are in good agreement with the transformation toughness increments derived from XRD data.