ISSN: 1546-962X
CODEN: JAIOAD
Published Online: 28 March 2008
Page Count: 20

Characterization of Zirconium Hydrides and Phase Field Approach to a Mesoscopic-Scale Modeling of Their Precipitation

Zhao, Z.
EDF R&D, centre des Renardières, Ecuelles, Moret-sur-Loing Cedex,
Laboratoire de Métallurgie Physique et Génie des Matériaux, USTL, ENSCL, CNRS, Villeneuve d’Ascq Cedex,

Blat-Yrieix, M.
EDF R&D, centre des Renardières, Ecuelles, Moret-sur-Loing Cedex,

Morniroli, J.-P.
Laboratoire de Métallurgie Physique et Génie des Matériaux, USTL, ENSCL, CNRS, Villeneuve d’Ascq Cedex,

Legris, A.
Laboratoire de Métallurgie Physique et Génie des Matériaux, USTL, ENSCL, CNRS, Villeneuve d’Ascq Cedex,

Thuinet, L.
Laboratoire de Métallurgie Physique et Génie des Matériaux, USTL, ENSCL, CNRS, Villeneuve d’Ascq Cedex,

Kihn, Y.
CEMES-CNRS, Toulouse Cedex 4,

Ambard, A.
EDF R&D, centre des Renardières, Ecuelles, Moret-sur-Loing Cedex,

Legras, L.
EDF R&D, centre des Renardières, Ecuelles, Moret-sur-Loing Cedex,

(Received 28 March 2007; accepted 21 January 2008)

Abstract

Zirconium alloys are currently used in nuclear power plants where they are submitted to hydrogen pick-up. Hydrogen in solid solution or hydride precipitation can affect the behavior of zirconium alloys during service but also in long term storage and in accidental conditions. Numerical modeling at mesoscopic scale using a “phase field” approach has been launched to describe hydride precipitation and its consequences on the mechanical properties of zirconium alloys. To obtain realistic results, it should take into account an accurate kinetic, thermodynamic, and structural database in order to properly describe hydride nucleation, growth, and coalescence as well as hydride interaction with external stresses. Therefore, an accurate structural characterization was performed on Zircaloy-4 plates and it allowed us to identify a new zirconium hydride phase called ζ. The ζ phase has a trigonal symmetry and is fully coherent with hcp αZr. The consequences of this new zirconium hydride phase on hydride transformation process and stress-reorientation phenomenon are discussed. A first attempt to numerically model the precipitation of this new zirconium hydride phase has been undertaken using the phase field approach.

Keywords:
Zircaloy-4, hydride, phase identification, precipitation process, phase field

Paper ID: JAI101161
DOI: 10.1520/JAI101161
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