Jean Couret

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• Type de publi. : Communication dans un congrès
• Date de publi. : 05/06/2015
• Auteurs : Alain CouretJean-Philippe P MonchouxThomas VoisinMarc Thomas
• Organismes : Physique de la Plasticité et Métallurgie Matériaux, ingénierie et science [Villeurbanne] Centre d'élaboration de matériaux et d'études structurales Physique de la Plasticité et Métallurgie

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• Type de publi. : Article dans une revue
• Date de publi. : 01/01/2015
• Auteurs : Thomas VoisinJean-Philippe P MonchouxLise DurandNikhil KarnatakMarc ThomasAlain Couret
• Organismes : Centre d'élaboration de matériaux et d'études structurales Centre d'élaboration de matériaux et d'études structurales Centre d'élaboration de matériaux et d'études structurales Mecachrome ONERA - The French Aerospace Lab [Châtillon] Centre d'élaboration de matériaux et d'études structurales
• Publié dans Advanced Engineering Materials le 25/10/2020

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Résumé : A study is conducted to show that the production of turbine blades in γ-TiAl alloys through spark plasma sintering (SPS) is a viable manufacturing route, by demonstrating that near-net shaping of γ-TiAl blades is successful, and by developing an alloy with balanced and outstanding mechanical properties at room and high temperatures in a single run and without subsequent thermal treatments. It is demonstrated that replacing nickel-based superalloys by such Intermetallic γ-TiAl alloys with high specific modulus and mechanical strength, combined with an exceptional resistance to oxidation, is an effective contribution to the development of lighter aircraft engines with high performance. Casting processes such as centrifugal cast have demonstrated that sound TiAl parts with a complex shape such as low-pressure turbine blades can be achieved.

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• Type de publi. : Communication dans un congrès
• Date de publi. : 23/09/2014
• Auteurs : Alain CouretJean-Philippe P MonchouxThomas VoisinMarc Thomas
• Organismes : Physique de la Plasticité et Métallurgie Matériaux, ingénierie et science [Villeurbanne] Centre d'élaboration de matériaux et d'études structurales Centre d'élaboration de matériaux et d'études structurales

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• Type de publi. : Article dans une revue
• Date de publi. : 01/01/2014
• Auteurs : Houria JabbarJean-Philippe P MonchouxMarc ThomasFlorian PyczakAlain Couret
• Organismes : Centre d'élaboration de matériaux et d'études structurales Centre d'élaboration de matériaux et d'études structurales ONERA - The French Aerospace Lab [Châtillon] Helmholtz-Zentrum Geesthacht Centre d'élaboration de matériaux et d'études structurales
• Publié dans Intermetallics le 31/10/2020

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Résumé : Thermal treatments are applied to PM TiAl alloys elaborated by Spark Plasma Sintering with the aim to improve their creep properties. Duplex microstructures are generated and characterized. © 2013 Published by Elsevier Ltd.

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• Type de publi. : Communication dans un congrès
• Date de publi. : 01/01/2014
• Auteurs : Zofia TrzaskaAlain CouretJean-Philippe P Monchoux
• Organismes : Centre d'élaboration de matériaux et d'études structurales Centre d'élaboration de matériaux et d'études structurales Centre d'élaboration de matériaux et d'études structurales

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Résumé : A method to observe the mechanisms occurring at the neck between TiAl powder particles during interrupted spark plasma sintering (SPS) cycles has been developed. It is based on co- sintering of a mixture of equilibrated TiAl prealloyed powder with a small amount of Ti powder, the latter taking the place of the pores. Dense samples were obtained, which could be prepared for scanning and transmission electron microscopies (SEM, TEM) by standard procedures. TiAl- Ti reaction proved to be sufficiently limited to allow observations of necks between TiAl particles. Though the neck regions exhibit large deformations, clean and dislocation-free grains are observed by TEM in these regions. This is interpreted in terms of classical high temperature mechanisms: dislocation activity followed by dynamic recrystallization. No mechanisms specific to the SPS have been observed. Copyright © 2014 by The Minerals, Metals & Materials Society.

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• Type de publi. : Article dans une revue
• Date de publi. : 01/01/2014
• Auteurs : Thomas VoisinJean-Philippe P MonchouxMuriel HantcherliSvea MayerHelmut ClemensAlain Couret
• Organismes : Centre d'élaboration de matériaux et d'études structurales Centre d'élaboration de matériaux et d'études structurales Centre d'élaboration de matériaux et d'études structurales Montanuniversität Leoben Montanuniversität Leoben Centre d'élaboration de matériaux et d'études structurales
• Publié dans Acta Materialia le 25/10/2020

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Résumé : This work deals with the densification of TNM alloys by spark plasma sintering. Pre-alloyed powders with composition Ti-43.9Al-4Nb-0.95Mo-0.1B (at.%) were sintered between 1237 and 1429 °C, applying a pressure of 100 MPa. The microstructures of the alloys were studied by scanning electron microscopy and transmission electron microscopy. Tensile tests at room temperature and creep experiments at 700 °C and 300 MPa stress were performed. Post-mortem analyses of deformed samples were also carried out by transmission electron microscopy to explain the mechanical properties. Duplex, nearly lamellar and so-called β microstructures were obtained as a function of the sintering temperature. Attention is focused on the nearly lamellar microstructure. This type of microstructure is composed of small lamellar α2/ γ-colonies, which are surrounded by γ + β0 intercolony borders. It exhibits very strong creep resistance associated with moderate ductility at room temperature. It is demonstrated that the use of β solidifying alloys during SPS is an efficient way to reduce the size of the lamellar microstructure. Finally, the mechanical properties obtained are explained in terms of the characteristics of this microstructure. © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

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• Type de publi. : Article dans une revue
• Date de publi. : 01/01/2013
• Auteurs : Thomas VoisinLise DurandNikhil KarnatakSophie Le GalletMarc ThomasYannick Le BerreJean-Francois CastagneAlain Couret
• Organismes : Centre d'élaboration de matériaux et d'études structurales Centre d'élaboration de matériaux et d'études structurales Laboratoire Interdisciplinaire Carnot de Bourgogne Centre d'élaboration de matériaux et d'études structurales
• Publié dans Journal of Materials Processing Technology le 25/10/2020

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Résumé : The determination and the homogeneity of the sample temperature during consolidation of powders by Spark Plasma Sintering (SPS) are addressed. Densifications were carried out in three different facilities differing by their constructors and their size. A structural transformation activated in a TiAl alloy was used as a marker of the sample temperature and finite element modeling were performed to evaluate the temperature at each point of the set-up. A good agreement between experimental and simulated data is exhibited. Alloys with identical microstructures were sintered and the homogeneity of the microstructure was better in the largest machines or when the sample was isolated by alumina disks. Large specimens with a diameter of 100 mm and a height of 60 mm were sintered, with the aim to achieve full densification and good microstructural control. On the basis of this temperature mastering, samples With complex shape were successfully densified. SEM post mortem observations confirmed the absence of porosities, and the expected microstructure as predicted by FEM calculations.

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• Type de publi. : Article dans une revue
• Date de publi. : 01/01/2010
• Auteurs : Houria JabbarJean-Philippe P MonchouxFlorent HoudellierMickaël DolléFrank-Peter SchimanskyFlorian PyczakMarc ThomasAlain Couret
• Organismes : Centre d'élaboration de matériaux et d'études structurales Centre d'élaboration de matériaux et d'études structurales Centre d'élaboration de matériaux et d'études structurales Laboratoire d'Analyse Microstructurale des Matériaux Centre d'élaboration de matériaux et d'études structurales Helmholtz-Zentrum Geesthacht Helmholtz-Zentrum Geesthacht ONERA - The French Aerospace Lab [Châtillon] Centre d'élaboration de matériaux et d'études structurales
• Publié dans Intermetallics le 31/10/2020

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Résumé : Spark Plasma Sintering (SPS) is used to process TNB alloys. Pre-alloyed powders (Tie-46Al-9Nb) were sintered between 975 °C and 1300 °C under 100 MPa. The microstructures of the products are determined by X-ray diffraction and by scanning and transmission electron microscopy. Their mechanical properties are evaluated by tensile tests performed at room temperature and creep experiments at 700 °C under 300 MPa stress. Depending on the sintering temperature, two-phased, duplex and lamellar microstructures have been obtained. A quasi-$\alpha$2 phase has been observed, which is in fact an $\alpha$2 phase in which Nb atoms have substituted Ti atoms. The TNB alloys consolidated by SPS are stronger than the alloys previously elaborated by SPS using Tie-47Al-2Cr-2Nb and Tie-44Al-2Cr-2Nb-1B powders but they exhibit a lower ductility. Moreover, some specimens broke prematurely due to Fe inclusions.

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Fichiers liés : Jabbar-intermet.pdf

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• Type de publi. : Chapître d'ouvrage
• Date de publi. : 01/01/1988
• Auteurs : Jean-Michel LattesFrédéric OgéAlain Couret
• Organismes : Laboratoire Interdisciplinaire de recherche sur les Ressources Humaines et l'Emploi Pôle de recherche pour l'organisation et la diffusion de l'information géographique Université Paris 1 Panthéon-Sorbonne

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Résumé : L'animal a toujours constitué un problème juridique. Faut-il lui attribuer les mêmes droits que l'être humain ? Cet article réalisé à l'occasion d'un colloque international tente de répondre à cette interrogation en utilisant l'exemple du spectacle.

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