Polythermal Sections of the Al2O3–ZrO2–La2O3 Phase Diagram

Three polythermal sections have been constructed for the Al2O3 ― ZrO2 ― La2O3system to give a more complete description of the phase diagram structure for it over wide ranges in temperature and concentration, which indicate the interactions in the ternary system. The 20 mole% ZrO2 (20Z) isoconcentrate gives the structure of a phase diagram in the region rich in Al2O3 and La2O3. The 60 mole% ZrO2 (60Z) isoconcentrate describes the structure in the region rich in ZrO2, and also the mechanism for the F ⇔ T phase transition for the solid solutions based on ZrO2. The bisector of the La2O3 ― (50 mole% Al2O3·50 mole% ZrO2) indicates the mechanism of the X ⇔ H ⇔ A phase transitions of solid solutions based on La2O3. These polythermal sections encompass all three triangulations of the sections of the ternary system and indicate the dynamics of the widths of the two-phase regions.