Pro- and Subeutectoid Behavior of the Tetragonal Phase in Magnesia-Partially-Stabilized Zirconia

Magnesia‐partially‐stabilized zirconia (Mg‐PSZ) is industrially important because of transformable metastable tetragonal precipitates which interact with and arrest cracks. This work addresses the precipitation of tetragonal phases at one composition, 9.5 mol% MgO, throughout a range of temperatures. High‐purity zirconia samples were sintered at 1700°C and rapidly quenched to heat‐treatment temperatures ranging from 1600° to 1100°C, then quenched to room temperature. Cooling rates through the tetragonal + MgO and the monoclinic + MgO two‐phase regions were found to affect the phase content. The kinetics of nonequilibrium phase transformation for high‐purity Mg‐PSZ are presented in terms of time‐temperature‐transformation diagrams.