Vertical sections of the Al2O3–HfO2–Er2O3 phase diagram

Abstract

For more complete description of the Al2O3–HfO2–La2O3 phase diagram, three vertical sections are constructed in a wide temperature and composition range. Isopleth 20 mol.% HfO2 (20H) shows the Al2O3–HfO2–La2O3 constitution in the Al2O3-rich region. Isopleth 60 mol.% HfO2 (60H) describes the ternary system in the Al2O3- and La2O3-rich regions and F ⇄ T phase transformation of HfO2 solid solutions. The radial La2O3–(50 mol.% Al2O3 · 50 mol.% HfO2) vertical section reveals the nature of X ⇄ H ⇄ A phase transformations of La2O3 solid solutions. The vertical sections intersect all three triangulating planes of the Al2O3–HfO2–La2O3 system and demonstrate variation in the width of their two-phase regions.