Effect of cation doping on the superplastic flow in yttria-stabilized tetragonal zirconia polycrystals

The superplastic characteristics of various cation-doped yttria-stabilized tetragonal zirconia polycrystals (Y-TZP) were examined. For 1 mol% cation d oping the true stress of Y-TZP is very dependent on the ionic radii of the doped cations; for instance, smaller cation radii give rise to lower true s tress when compared with the other compositions for the same grain size, st rain rate, and testing temperature. The altered true stress level must be d ue to the change in diffusivity of the accommodation process for grain boun dary sliding caused by the addition of cations in ZrO2. The strain to failu re of the doped zirconia is affected by both ionic radius and valence of th e dopant cations.