Low oxygen partial pressure oxidation in a model Ni-30Cr alloy between 500 and 900°C : point defects and oxidation mechanisms in chromia. - CEA - Commissariat à l’énergie atomique et aux énergies alternatives Accéder directement au contenu
Communication Dans Un Congrès Année : 2022

Low oxygen partial pressure oxidation in a model Ni-30Cr alloy between 500 and 900°C : point defects and oxidation mechanisms in chromia.

Résumé

Ni-based alloys containing high Cr concentrations are considered as structural materials for present and future nuclear reactors [1,2]. Indeed, their good corrosion resistance is provided, at intermediate and high temperature (300 to 900 °C), by the formation of a protective chromia scale on the alloy surface. Growth kinetics of chromia scale follows a parabolic law with a parabolic constant kp which depends on the nature, the concentration, and the diffusivity of the predominant point defects in the chromia scale [3]. The growth of this layer can be limited by either anionic (O2-) or cationic (Cr3+) diffusion. However the nature of the diffusing element (cation or anion) and of the point defects involved in its diffusion process in chromia is still not clear. Indeed, various defects (oxygen and chromium vacancies, chromium interstitials) were identified for chromia scale growing on Ni-Cr [4_6] and other chromia-forming alloys [7_13]. Both (diffusing element and its defects) can depend on the nature of the alloy and on oxidation conditions such as temperature and atmosphere. The oxidation kinetics of chromia-forming alloys, depending on the diffusion defects and then on the alloy nature and the oxidizing environment are then very scattered. The aim of this work is to clarify what happens during the oxidation of a Ni-Cr model alloy containing 30 wt% of Cr. The objective is to study the effect of oxidation temperature on the nature of the predominant point defects responsible for the chromia scale growth and to propose a growth mechanism. To this intent, thermogravimetric analysis (TGA), photoelectrochemistry (PEC), 18O and 54Cr tracers experiments and SIMS and nanoSIMS analysis have been carried out.

Domaines

Matériaux
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Dates et versions

cea-04244646 , version 1 (16-10-2023)

Identifiants

  • HAL Id : cea-04244646 , version 1

Citer

Xian Huang, Sophie Bosonnet, Laure Martinelli, Paul Fossati, Yves Wouters, et al.. Low oxygen partial pressure oxidation in a model Ni-30Cr alloy between 500 and 900°C : point defects and oxidation mechanisms in chromia.. ISHOC-2022, Oct 2022, Takamatsu, Japan. ⟨cea-04244646⟩
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