PHASE-EQUILIBRIA IN THE SYSTEM ZRO2-INO1.5

Phase equilibria in the system ZrO2-InO1.5 have been investigated in the temperature range from 800-degrees to 1700-degrees-C. Up to 4 mol%, InO1.5 is soluble in t-ZrO2 at 1500-degrees-C. The martensitic transformation temperature m --> t of ZrO2 containing InO1.5 is compared with that of ZrO2 solid solutions with various other trivalent ions with different ionic radii. The diffusionless c --> t' phase transformation is discussed. Extended solid solubility from 12.4 +/- 0.8 to 56.5 +/- 3 mol% InO1.5 is found at 1700-degrees-C in the cubic ZrO2 phase. The eutectoid composition and temperature for the decomposition of c-ZrO2 solid solution into t-ZrO2 + InO1.5 solid solutions were determined. A maximum of about 1 mol% ZrO2 is soluble in bcc InO1.5 phase. Metastable supersaturation of ZrO2 in bcc InO1.5 and conditions for phase separation are discussed.