Grant-in-Aid for General Scientific Research (B)
The microstructure formed by the cubic-to-tetragonal (c-t) transformation was examined in detail. The domain structure and plate-like or lenticular microstructures were developed in tetragonal zirconia (t-ZrO_2) generated by rapid cooling from high-temperature cubic phase (cZrO_2). The c-t transformation was always completed with a formation of the domain structure. The modulated structure characteristic of spinodal decomposition was found in ZrO_2-Y_2O_3 annealed in the c-t two-phase region. From the microstructural evidence, the author has proposed that the c-t transformation has a nature of second-order phase transition.The thermodynamic analysis on the c-t equilibrium was made by assuming that this transformation is of the second-order type. The result satisfactorily explained the reported c-t equilibrium.
Attribution of KAKENHI