Tensile Ductility in Zirconia-Dispersed Alumina at High Temperatures

High-temperature plastic flow in Al₂O₃-10 wt% ZrO₂ (2.5 mol% Y₂O₃) has been examined at temperatures between 1400° and 1500°C. Al₂O₃-10 wt% ZrO₂ (2.5 mol% Y₂O₃) exhibits much higher flow stress and smaller tensile elongation below about 1450°C than 0.1 wt% MgO-doped single-phase Al₂O₃. The suppression of grain growth with ZrO₂ dispersion into Al₂O₃ is not effective for improving the tensile ductility. The limited ductility in Al₂O₃-10 wt% ZrO₂ (2.5 mol% Y₂O₃) is associated with the increment of flow stress caused by ZrO₂. The ZrO₂ dispersion or segregation in Al₂O₃/Al₂O₃ boundaries suppresses the grain boundary sliding and hence results in the increased flow stress at high temperatures.