Abstract
Y2O3-partially stabilized zirconia shows various microstructures, for example, twinned, herring-bone, lenticular, domain, tweed, modulated, martensitic tetragonal structures, anti-phase boundaries and short range ordering. In order to interpret the formation mechanisms of these structures, the phase diagram of the ZrO2–Y2O3 system at low Y2O3 contents proposed by the present authors was investigated. It was concluded that cubic-tetragonal transformation in ZrO2 was para-ferroelastic second order transition and that the (cubic+tetragonal) two-phase region in the diagram was regarded as a miscibility gap. From these standpoints, the formation mechanisms of complex microstructures are also discussed.
