Room-temperature plasticity of alumina-toughened zirconia with silica addition

Alumina-toughened zirconia (ATZ) is widely used in various fields due to its unique complex of mechanical properties. However, brittle fracture at room temperature remains a significant drawback of the material. Special additives are used to induce plasticity due to the martensitic transformation of the tetragonal t-ZrO2 phase into monoclinic m-ZrO2. The room-temperature uniaxial compression deformation of bulk ATZ ceramics with variable silica content (0 mol% ≤ CSiO2 ≤ 6 mol%) was studied in this paper. X-ray diffraction was used to monitor phase composition of the material at different deformation stages. It was shown that the SiO2 addition to the ATZ ceramics causes the stress reduction required for the t-ZrO2 → m-ZrO2 phase transformations. This provides strengthening the role of a transformation toughening mechanism (increase in the compressive strength from 2.12 GPa to 2.55 GPa) and appearance of transformation plasticity (residual deformation εP = 0.5%). The results obtained and the conclusions drawn made it possible to advance the understanding of the physical nature of ATZ + SiO2 ceramics plastic deformation at room temperature. •Silica addition into ATZ ceramics provides it with plasticity at room temperatures.•Room temperatures ATZ plasticity is provided due to tetragonal-monoclinic phase transformations.•SiO2 addition causes in ATZ an increase in the transformability of the ZrO2 tetragonal phase.•Exceeding the SiO2 critical concentration in ATZ prevents the ZrO2 tetragonal phase stabilization.