TRANSFORMATION-TOUGHENING IN PARTIALLY-STABILIZED ZIRCONIA (PSZ)

The significant fracture toughness of optimally-fabricated partially-stabilized zirconia (PSZ) is due to mechanical energy absorption in the vicinity of the tip of a propagating crack due to stressinduced phase transformations occurring within metastable precipitates. Eshelby's transformed-inclusion analysis has been used to model the transformation toughening: a transformation zone is calculated from an energy balance approach, the size of this zone determining the mechanical energy dissipated during crack propagation. The increase in apparent fracture surface energy predicted by the model is in tolerable agreement with experiment, although the model does not account for multiparticle interactions, interfacial energy changes, and transformation-induced twinning. © 1979.