Transformation Zone Shape Effects on Crack Shielding in Ceria-Partially-Stabilized Zirconia (Ce-TZP)-Alumina Composites

摘要

Crack tip shielding is evaluated for observed transformation zones in Ce-TZP/Al2O3 composites, in which the transformation zone sizes were changed significantly by varying the sintering temperature to control the transformation yield stress. The calculated shielding effects are consistent with an observed insensitivity of crack resistance curves to transformation zone size; smaller zones in materials with higher yield stress were associated with larger ratios of wake length to zone width and corresponding higher normalized shielding stress intensity factors. Shielding due to the dilatational component of the transformation strain accounted for most of the toughening observed in these materials. (Author).