Transformation Toughening in Large‐Grain‐Size CeO ₂ ‐Doped ZrO ₂ Polycrystals

Abstract

The fracture and transformation behavior of tetragonal polycrystalline ZrO 2 alloys containing 18 mol% CeO 2 (Ce‐TZP) was investigated. In the absence of applied stress the tetragonal phase was found to be stable in large‐grained (>30 μm) samples at room temperature. The monoclinic phase was detected in regions of high residual stress near hardness indentations although no evidence of a wake of monoclinic phase along the fracture surface was observed. The fracture toughness increased from 4 to 7 MPa · m 1/2 as density and/or grain size increased. It is proposed that the relatively high toughness of these materials is due to the occurrence of stress‐driven tetragonal‐to‐monoclinic transformation near the crack tip, which reverses when the crack has passed.