Fabrication, Microstructural Characterization, and Mechanical Properties of Polycrystalline t '‐Zirconia

Large‐grained (100‐ to 200‐μm), yttria‐doped, polycrystalline t '‐zirconia ceramics were fabricated by heat‐treating presintered samples at temperatures 2100°C. Polarized light microscopy revealed the ferroelastic domain structure in the t ' samples. XRD showed that no monoclinic phase was detected on as‐polished, ground and fracture surfaces, or on surfaces while under a tensile stress as high as 400 MPa. By contrast, relative changes occurred in the tetragonal peak intensities, which were attributed to ferroelasatic domain switching. The higher toughness of 3‐mol%‐Y 2 O 3 ‐doped t ' samples (7.7 MPa · m 1/2 ) compared to that of 8 mol% Y 2 O 3 cubic samples (2.4 MPa · m 1/2 ) was explained in part by ferroelastic domain switching.