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Relation entre la microstructure, l'état mécanique et la fissuration de cermets alumine chrome élaborés à partir de poudres nanocomposites

Abstract : Alumina chromium composites are obtained by hot pressing of powders elaborated by reactive milling of aluminium, alumina and chromium oxides powders. Various composites have been characterised, corresponding to different volume fraction of chromium and different processing routes. A microstructural study has been made for a better knowledge of the different phases in the powders and in the dense samples (notably the minority phases). A micromechanical approach has been used for the determination of the local stress field, generated during cooling, after the hot pressing of powders, coming from the difference between thermal expansion coefficients and thermo-mechanical properties of the phases. These differences and stress states that could conduct to damaging the composite and crack initiation, can be advantageously used to reinforce the composite, locally depending on the size and distribution of the reinforcement phase. Results from calculation have been compared to the experimental result of mean stress determination in the phases, using the synchrotron radiation. To analyse the behaviour of the microstructure and mechanical state in relation with the crack propagation, an experimental set-up of Hertzian indentation (indentation of a plane sample with a sphere) has been used to analyse the crack mode of the dense samples. Results from microstructure study, calculations and crack analysis have been compared to analyse the influence of microstructure and mechanical state on the crack behaviour in the two-phases alumina chromium composites. Concrete ways of improvement and optimisation of the microstructure in regard to the crack propagation resistance have been brought out.
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https://tel.archives-ouvertes.fr/tel-01749770
Contributor : Guillaume Geandier <>
Submitted on : Thursday, June 10, 2004 - 2:02:56 PM
Last modification on : Thursday, February 25, 2021 - 1:10:02 PM
Long-term archiving on: : Tuesday, September 7, 2010 - 5:11:12 PM

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  • HAL Id : tel-01749770, version 2

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Guillaume Geandier. Relation entre la microstructure, l'état mécanique et la fissuration de cermets alumine chrome élaborés à partir de poudres nanocomposites. Mécanique [physics.med-ph]. Institut National Polytechnique de Lorraine - INPL, 2002. Français. ⟨NNT : 2002INPL067N⟩. ⟨tel-01749770v2⟩

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