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Modélisation des cinétiques de transformations multiples dans les alliages métalliques : étude de la microségrégation lors de la solidification dendritique, péritectique et eutectique d'alliages aluminium-nickel

Abstract : Atomised powders of aluminium-nickel alloys may be processed to obtain Raney nickel, a catalyst used in numerous industrial processes. Catalytic activity strongly depends on the progress of the multiple solidification reactions during atomisation. A microsegregation model for metallic alloys solidification is thus developed. Considering finite diffusion fluxes, dendritic, peritectic and eutectic reactions kinetics and nucleation undercoolings, an advanced alternative to Gulliver-Scheil model or the lever rule is proposed. Coupling with thermodynamic equilibrium calculations is achieved to evaluate interfacial compositions and enthalpy terms in the energy balance. The model is applied to a binary alloy, with constant densities of phases, to simulate the atomisation process of Al-Ni alloy droplets. A dedicated model is chosen for the heat transfer boundary conditions. Results are compared to measurements from neutron diffraction experiments. Interpretations are thus given on the non trivial behaviour of rapidly solidified Al-Ni alloys. The proposed model allows estimating concurrent effects of different kinetics (chemical diffusion, heat balance, microstructures growth kinetics, etc.) during solidification out of equilibrium. Main prospective developments from this work include: extension to multicomponent alloys, introduction of variable densities, coupling with macroscopic calculations.
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https://pastel.archives-ouvertes.fr/pastel-00005817
Contributor : Ecole Mines Paristech <>
Submitted on : Tuesday, February 16, 2010 - 8:00:00 AM
Last modification on : Tuesday, October 20, 2020 - 11:23:17 AM
Long-term archiving on: : Friday, September 10, 2010 - 3:02:42 PM

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  • HAL Id : pastel-00005817, version 1

Citation

Damien Tourret. Modélisation des cinétiques de transformations multiples dans les alliages métalliques : étude de la microségrégation lors de la solidification dendritique, péritectique et eutectique d'alliages aluminium-nickel. Sciences de l'ingénieur [physics]. École Nationale Supérieure des Mines de Paris, 2009. Français. ⟨NNT : 2009ENMP1664⟩. ⟨pastel-00005817⟩

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