Vertical Sections of the Al₂O₃–HfO₂–La₂O₃ Phase Diagram

Abstract

For more complete description of the Аl₂О₃–HfO₂–Lа₂О₃ phase diagram, three vertical sections are constructed in a wide temperature and composition range. The isopleth 20 mol.% HfO₂ (20H) shows the Аl₂О₃–HfO₂–Lа₂О₃ constitution in the Аl₂О₃- and Lа₂О₃-rich regions. The isopleth 60 mol.% HfO₂ (60H) describes the ternary system in the HfO₂-rich region and the phase transformation of HfO₂ solid solutions. The radial Lа₂О₃–(50 mol.% Аl₂О₃•50 mol.% HfO₂) vertical section reveals the nature of Lа₂О₃ phase transformations X ⇄ H ⇄ A. The vertical sections intersect all three triangulating sections of the Аl₂О₃–HfO₂–Lа₂О₃ system and demonstrate variation in the width of their two-phase regions.