A Raman study of the nanocrystallite size effect on the pressure–temperature phase diagram of zirconia grown by zirconium-based alloys oxidation - CNRS - Centre national de la recherche scientifique Accéder directement au contenu
Article Dans Une Revue Journal of Nuclear Materials Année : 2002

A Raman study of the nanocrystallite size effect on the pressure–temperature phase diagram of zirconia grown by zirconium-based alloys oxidation

Résumé

The pressure–temperature phase diagrams of different zirconia samples prepared by oxidation of Zircaloy-4 and Zr–1%Nb–0.12O alloys were monitored by Raman spectrometry from 0.1 MPa to 12 GPa and from 300 to 640 K. These new diagrams show that the monoclinic–tetragonal equilibrium line is strongly downshifted in temperature compared to literature measurements performed on usual polycrystalline zirconia. In addition, the monoclinic–orthorhombic equilibrium line is slightly shifted to higher pressure (i.e. 6 GPa). The crystallite sizes smaller than 30 nm, are thought to be responsible for these equilibrium line displacements. The tetragonal phase obtained in temperature under high pressure can be quenched at room temperature, if the pressure is maintained, and it is destabilised and transforms completely into monoclinic phase if the pressure is released. These results confirm that coupled effects of stress, temperature and nanosized grain are responsible for the formation of the tetragonal phase near the metal/oxide interface during the oxidation of zirconium-based alloys.

Domaines

Matériaux

Dates et versions

hal-00418107 , version 1 (17-09-2009)

Identifiants

Citer

Pierre Bouvier, J. Godlewski, Guy Lucazeau. A Raman study of the nanocrystallite size effect on the pressure–temperature phase diagram of zirconia grown by zirconium-based alloys oxidation. Journal of Nuclear Materials, 2002, 300 (2-3), pp. 118-126. ⟨10.1016/S0022-3115(01)00756-5⟩. ⟨hal-00418107⟩
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