Jean Couret

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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. : 01/01/2013
• 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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