Microstructural Characterization of Superplastic SiO 2 ‐doped TZP with a Small Amount of Oxide Addition

The microstructures of 5 wt% SiO 2 ‐doped TZP, 5 wt% (SiO 2 + 2 wt% MgO)‐doped TZP, and 5 wt% (SiO 2 + 2 wt% Al 2 O 3 )‐doped TZP are characterized by high‐resolution electron microscopy, energy‐dispersive X‐ray spectroscopy, and electron energy loss spectroscopy. An amorphous phase is formed at multiple grain junctions but not along the grain‐boundary faces in these three materials. A small addition of MgO and Al 2 O 3 into the SiO 2 phase results in a marked reduction in tensile ductility of SiO 2 ‐doped TZP. This reduction seems to correlate with segregation of magnesium or aluminum ions at grain boundaries and a resultant change in the chemical bonding state.