Stability of tetragonal ZrO2 toward external influences

The response of the nonequilibrium phase T-ZrO2 to various physicochemical influences was studied by x-ray diffraction analysis. The results indicate a significant sensitivity of the T-ZrO2 --> M-ZrO2 phase transition to some of the influences: pressing at elevated temperatures (100-250degreesC) accelerates the formation of the equilibrium phase, whereas Al2O3 additions notably slow down the process (stabilize the metastable phase T-ZrO2). Mechanochemical treatment and freezing at 77 K have no effect on the character of the phase transition.