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The Zirconia–Hafnia System: DTA Measurements and Thermodynamic Calculations
Author(s) -
Wang Chong,
Zinkevich Matvei,
Aldinger Fritz
Publication year - 2006
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2006.01286.x
Subject(s) - monoclinic crystal system , hafnia , phase diagram , tetragonal crystal system , materials science , differential thermal analysis , thermodynamics , diffusionless transformation , cubic zirconia , gibbs free energy , atmospheric temperature range , phase (matter) , mineralogy , martensite , crystallography , chemistry , crystal structure , diffraction , metallurgy , microstructure , ceramic , physics , organic chemistry , optics
The equilibrium temperature ( T 0 ) at which the tetragonal and monoclinic phases of either ZrO 2 or HfO 2 coexist is generally defined by the middle temperature of A s (the onset transformation temperature on heating) and M s (the onset transformation temperature on cooling). It cannot be directly determined due to the athermal nature of the martensitic transformation. Practically, the determination of T 0 is important for the prediction of A s and M s in ZrO 2 or HfO 2 ‐based materials. In this work, the ZrO 2 –HfO 2 system was studied experimentally by differential thermal analysis (DTA) to obtain the martensitic tetragonal ⇔ monoclinic transformation temperatures in the temperature range of 1273–1973 K. The T 0 temperatures obtained for ZrO 2 and HfO 2 are 1367±5 and 2052±5 K, respectively. They are adopted for the assessments of the Gibbs energy parameters of these two oxides. A reasonably calculated ZrO 2 −HfO 2 phase diagram is presented.