Évolution des propriétés physico-chimiques de surface des matériaux quasicristallins lors de sollicitations électrochimiques

Abstract : The main goal of this study is to understand how the surface properties of quasicrystalline and approximant alloys are modified when submitted to various kinds of electrochemical stress. The alloys are Al-based complex intermetallic phases of the AI-(Cu)-Fe-Cr system, submitted to either corrosion test in aggressive media or simply to oxidation and ageing in ambient conditions. ln a first part, bulk alloys of the AI-(Cu)-Fe-Cr system were synthesized and their atomic structure was characterised. Then, the corrosion behaviour of these alloys was investigated with a view to identify the role of the chemical composition and of the crystallographic structure on their ability to resist corrosion attack in a medium containing citric acid and chloride anions. This work bas allowed us to âetermine the corrosion mechanisms and to identify some alloy compositions which demonstrate high-resistance against corrosion. The last part focusses on the evolution of surface structure and chemistry as a function of electrochemical stress. The topography, composition and structure of corroded samples were analysed. ln addition, for AICrFe samples, we have highlighted an ageing phenomenon of the surfaces in ambient conditions. We have proposed a model describing the surface of these materials as a stacking of several layers with different chemistry. The surface ageing is modelled and related to the observed modifications of the chemical reactivity.
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Theses
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http://docnum.univ-lorraine.fr/prive/INPL_T_2004_VEYS_D.pdf
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Submitted on : Thursday, March 29, 2018 - 12:37:20 PM
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Delphine Veys. Évolution des propriétés physico-chimiques de surface des matériaux quasicristallins lors de sollicitations électrochimiques. Autre [cond-mat.other]. Institut National Polytechnique de Lorraine, 2004. Français. ⟨NNT : 2004INPL076N⟩. ⟨tel-01750077⟩

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