Papers by Author: J. Baruchel

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Authors: H.J. Jung, Nathalie Mangelinck-Noël, Henri Nguyen-Thi, Nathalie Bergeon, Bernard Billia, Adeline Buffet, J. Baruchel
Abstract: The columnar to equiaxed transition (CET) has been widely studied for many years [1] because this phenomenon is observed in metallurgical applications like castings. In non refined alloys, detachment of dendrite fragments is the most probable mechanism responsible for the formation of an equiaxed microstructure [1]. In this frame, melt convection influences the grain structure evolution by playing a role in the fragmentation phenomena [2].
Authors: Guillaume Reinhart, Henri Nguyen-Thi, J. Gastaldi, Bernard Billia, Nathalie Mangelinck-Noël, Thomas Schenk, J. Härtwig, J. Baruchel
Abstract: Solidification is a dynamic phenomena and, as a consequence, it is of major interest to be able to investigate this process by in situ and real time observation. With synchrotron sources, this can be achieved by applying X-ray Imaging techniques (Radiography and Topography). Hence it is possible to follow the dynamical selection of solidification pattern on metallic alloys and to observe strain effects during growth process. In this paper, we present results obtained by using separately the two imaging techniques for the study of the microstructure formation during Al – Ni alloys solidification.
Authors: E. Pereiro-López, Wolfgang Ludwig, Daniel Bellet, J. Baruchel
Authors: Adeline Buffet, Henri Nguyen-Thi, Aziz Bogno, Thomas Schenk, Nathalie Mangelinck-Noël, Guillaume Reinhart, Nathalie Bergeon, Bernard Billia, J. Baruchel
Abstract: In the present study, we report on an image analysis procedure, which enables to extract from synchrotron radiographs the long range solute profiles in the whole sample and in both phases (solid and liquid). This image analysis is based on the measurement of local density differences, and is applied to study the directional solidification of Al - 4wt% Cu alloy, from planar to onset of the initial instability. Dedicated experiments were carried out at the European Synchrotron Radiation Facility (ESRF) in Grenoble (France). In order to validate this analysis the value of a key solidification parameter, namely the partition coefficient, was experimentally determined during the planar solidification, and a very good agreement was found with value found usually in the literature. On a further step, the evolution of the microstructure and solute profile during the initial transient of solidification was analysed in detail.
Authors: Bernard Billia, Henri Nguyen-Thi, Guillaume Reinhart, Nathalie Mangelinck-Noël, J. Gastaldi, Thomas Schenk, J. Hartwig, J. Baruchel, V. Cristiglio, B. Grushko, Holger Klein
Abstract: The solid microstructure built in the solid governs the properties of materials elaborated from the melt. In order to clarify the dynamical mechanisms controlling solidification processing, we use in situ and real-time synchrotron X-ray radiography at ESRF (European Synchrotron Radiation Facility) to analyze microstructure formation in thin aluminum alloys solidified in the Bridgman facility installed at the ID19 beamline. During directional solidification of Al - 3.5 wt% Ni alloys, global mechanical constraints induced by the shape are found to act on the solid microstructure. In particular, radiography videos of dendritic growth show disorientations of sidebranches induced by mechanical stresses. In the solidification of AlPdMn quasicrystals, live imaging reveals that facetted growth proceeds by the lateral motion of ledges at the solid-melt interface. When the solidification rate is increased, the kinetic undercooling becomes sufficient for grain nucleation and growth in the liquid. These grains develop specific features that can be attributed to grain competition and concomitant poisoning of growth caused by the rejection of aluminum in the melt.
Authors: S. Milita, R. Pons, J. Baruchel, A. Mazuelas
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