The Domain Structure of Tetragonal Zirconia in ZrO2-Y2O3 Alloys

The microstructural features formed by the diffusionless cubic-to-tetragonal(c-t) transition in ZrO2 –Y2O3 alloys were examined by electron microscopy with a special interest in domain structure. The diffusionless c-t transition accompanies two types of microstructures, thin plates or lenticular features and domain structure. These microstructures were found in ZrO2-(3-7)mol%Y2O3 alloys rapidly-cooled from single cubic phase region, but not in ZrO2-8 mol%Y2O3 alloy. The domain structure was always found in a whole region or the sample, and the domain size decreased with an increase of yttria content. On the basis of microstructural examinations, it was concluded that the diffusionless c-t transition has a nature of second order phase transition.