The effect of Β-phase, Mg/sub 2/Zr/sub 5/O/sub 12/, on the stabilization of the tetragonal phase in MgO-Psz

The formation of an ordered anion vacancy phase, Mg/sub 2/Zr/sub 5/O/sub 12/ (Β-phase), has been examined in thin foils of MgO-partially stabilized zirconia (MgO-PSZ) with the electron microscopy techniques. The results indicate that the phase of Mg/sub 2/Zr/sub 5/O/sub 12/ was formed in the region of cubic solid solution matrix following the precipitation of tetragonal phase. The results also indicate that the Β phase could nucleate at a temperature higher than 9000C. The presence of the Β-phase may have a significant effect on the transformation of the tetragonal phase into the structure of lower symmetry, monoclinic or orthorhombic phase. The authors suggest that the t - o phase transformation due to the presence of Β-phase enhances the thermomechanical properties of MgO-PSZ