On a martensitic phase transformation in zirconia (ZrO 2)—II. Crystallographic aspects

Abstract

Crystallographic aspects of the martensitic tetragonal → monoclinic phase transformation in zirconia single crystals have been studied experimentally and compared with predictions of the phenomenological theory of martensite crystallography. Two different orientation relationships have been observed between the high and low temperature phases. Above 1000°C, the transformation occurs according to the orientation relations (100) m∥~(100) t and [010] m∥~[001] t, while below 1000°C, (100) m~(100) t and [001] m∥~[001] t were observed. These results indicate that the habit planes of the plate-like martensite products reported in the first paper of this series [ Acta Met. 20, 1281 (1972)] had been incorrectly indexed; this occurred because of an incorrect assumption that a single crystal undergoing a monoclinie → tetragonal → monoclinic cycle would return to its original orientation at the end of the cycle. Application of the phenomenological theory of martensite crystallography indicates that the observed habit planes can be predicted using a single Bain correspondence, implied by the lower temperature orientation relations, combined with different lattice invariant deformation modes.