Phase Relations in the System ZrO2-Y2O3 at Low Y2O3 Contents

Subsolidus phase relations in the low-Y₂O₃ portion of the system ZrO_2-Y₂O₃ were studied using DTA with fired samples and X-ray phase identification and lattice parameter techniques with quenched samples. Approximately 1.5% Y₂O₃ is soluble in monoclinic ZrO₂, a two-phase monoclinic solid solution plus cubic solid solution region exists to ～7.5% Y₂O₃ below ～500°C, and a two-phase tetragonal solid solution plus cubic solid solution exists from ～1.5 to 7.5% Y₂O₃ from ～500° to ～1600°C. At higher Y₂O₃ compositions, cubic ZrO₂ solid solution occurs.