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In situ and real-time 3-D microtomography investigation of dendritic solidification in an Al–10wt.% Cu alloy

type de publication      article dans une revue internationale avec comité de lecture
date de publication 2009
auteur(s) Limodin Nathalie; Salvo Luc; Boller Elodie; Suery Michel; Felberbaum Milan; Gailliègue Sylvain; Madi Kamel
journal (abréviation) Acta Materialia (Acta Mater)
volume (numéro) 57 (7)
  
pages 2300 – 2310
résumé The microstructural evolution of an Al-10wt%Cu alloy was investigated during solidification at constant cooling rate by in-situ synchrotron X-Ray microtomography with a resolution of 2.8 µm. Solidification of this alloy leads to a coarse dendritic microstructure which was fully characterized in terms of variation with temperature of solid fraction, specific surface area of the solid-liquid interface and local curvatures of the solid phase. By analysing the evolution with solid fraction of individual dendrites, at least two coarsening mechanisms were clearly identified in addition to solidification growth. The first mechanism involves remelting of small secondary dendrite arms to the benefit of bigger adjacent arms. The second is the coalescence of adjacent secondary arms, with progressive filling of the inter-arm spacing and coalescence at the tips. Although this mechanism preferentially occurs at high solid fractions, these results show that the evolution of the dendritic microstructure during solidification is complex and involves the occurrence of various mechanisms operating concurrently. In-situ X-Ray tomography thus allows revisiting the various models which have been proposed to account for dendrite coarsening during solidification.
mots clés semi-solid; 3D X-ray tomography; aluminium alloys; dendritic solidification; coarsening.
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