The Al2O3–HfO2–Gd2O3 Phase Diagram.
I. Isothermal Sections at 1250 and 1650 °С

   
L.Lopato
 

I. M. Frantsevich Institute for Problems of Materials Science of the NAS of Ukraine, Krzhizhanovsky str., 3, Kyiv, 03142, Ukraine
Powder Metallurgy - Kiev: Frantsevich Institute for Problems of Materials Science NASU, 2012, #01/02
http://www.materials.kiev.ua/article/987

Abstract

The isothermal sections of the Al2O3–HfO2–Gd2O3 phase diagram at 1250 and 1650 °C are constructed for the first time and phase equilibria at these temperatures are established. No ternary compounds and appreciable solid solution regions based on components or binary compounds are found in the ternary system. Interaction in the system is determined by the most thermodynamically stable compound, HfO2, which equilibrates with all phases in the system. In the region with Gd2O3 content up to ~65%, the sections are similar, only width of the regions changes; which is connected with changes in the extension of M and F solid solutions in the HfO2–Gd2O3 binary bounding system. The presence of two-phase AL + F, GA + GH2, and G2A + F regions in the isothermal sections suggests that there are triangulating sections of the Al2O3–HfO2–Gd2O3 system in them. Since the F and GH2 phases are of variable composition, these sections can be qualified as conditionally quasibinary. In wide three-phase regions, like in the Al2O3–ZrO2–Gd2O3, system, ternary eutectic points are expected to exist.


ALUMINA, CERAMIC HFO2, CERAMICS, EUTECTIC MATERIALS, GADOLYNIA, INTERACTION, ISOTHERMAL SECTION, STATE DIAGRAM