Modélisation de la solidification de gouttes atomisées

Abstract : It's well known that, from the structural point of view, the parts formed by powder metallurgy processes are quite homogeneous on a macroscopic scale (of the product). Does it go in the same way on the scale of the particles which compose these parts? In this work we present results of local measurements of the species composition made on atomized Al-Cu droplets. This analysis shows a non-uniform distribution of alloy compounds in the observed sections of the droplets. A numerical model was proposed for the solidification of a spherical droplet subject to convection. The solidification starts with an imposed undercooling at the center of the droplet and progresses spherically towards its external surface. Volume average of the energy and solute balances was taken for each phase. The numerical solution of these equations allowed to evaluate the distributions of the enthalpy, temperature, phase fractions, and solute composition in the droplet. Results are presented for a droplet of Al 10%mass Cu, and nucleation undercooling of 0, 30 and 60 °C. The model predicts the solute segregation in the droplet. It predicts also a systematic remelting of the supersaturated solid structures, which can be related with fragmentation and possible grain refining.
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Theses
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http://docnum.univ-lorraine.fr/prive/INPL_T_2004_HERINGER_FERREIRA_R_A.pdf
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https://hal.univ-lorraine.fr/tel-01750033
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Submitted on : Thursday, March 29, 2018 - 12:36:18 PM
Last modification on : Monday, April 16, 2018 - 10:41:29 AM

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Romulo Adolfo Heringer Ferreira. Modélisation de la solidification de gouttes atomisées. Autre [cond-mat.other]. Institut National Polytechnique de Lorraine, 2004. Français. ⟨NNT : 2004INPL093N⟩. ⟨tel-01750033⟩

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