Coarsening mechanisms in a dendritic Al–10% Cu alloy / S. Terzi in Acta materialia, Vol. 58 N° 1 (Janvier 2010)  

Public ISBD [article]  inActa materialia > Vol. 58 N° 1 (Janvier 2010) . - pp. 20–30 Titre : Coarsening mechanisms in a dendritic Al–10% Cu alloy Type de document : texte imprimé Auteurs : S. Terzi, Auteur ; L. Salvo, Auteur ; M. Suery, Auteur Année de publication : 2010 Article en page(s) : pp. 20–30 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Coarsening Aluminium alloys X-ray microtomography Solidification microstructure Semi-solid processing Résumé : Coarsening of a dendritic Al–10 wt.% Cu alloy at 570 °C was investigated by fast in situ X-ray tomography. The variation of the specific solid–liquid interface area as a function of time was found to follow a power-law relation with an exponent close to −1/4. Three coarsening mechanisms operate in the alloy: (i) melting of small dendrite arms to the benefit of the adjacent arms (small arm melting), similar to Ostwald ripening; (ii) gradual movement of the base of the interdendritic grooves towards the tips (interdendritic groove advancement); (iii) coalescence of dendrites near the tips leading to the entrapment of liquid tubes or droplets (coalescence and groove advancement). The coarsening models proposed in the literature do not adequately resemble or predict the behaviour observed in the experiments. New models were developed for the first two coarsening mechanisms and predict the coarsening rate with very good agreement. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409005655 [article] Coarsening mechanisms in a dendritic Al–10% Cu alloy [texte imprimé] / S. Terzi, Auteur ; L. Salvo, Auteur ; M. Suery, Auteur . - 2010 . - pp. 20–30. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 1 (Janvier 2010) . - pp. 20–30 Mots-clés : Coarsening Aluminium alloys X-ray microtomography Solidification microstructure Semi-solid processing Résumé : Coarsening of a dendritic Al–10 wt.% Cu alloy at 570 °C was investigated by fast in situ X-ray tomography. The variation of the specific solid–liquid interface area as a function of time was found to follow a power-law relation with an exponent close to −1/4. Three coarsening mechanisms operate in the alloy: (i) melting of small dendrite arms to the benefit of the adjacent arms (small arm melting), similar to Ostwald ripening; (ii) gradual movement of the base of the interdendritic grooves towards the tips (interdendritic groove advancement); (iii) coalescence of dendrites near the tips leading to the entrapment of liquid tubes or droplets (coalescence and groove advancement). The coarsening models proposed in the literature do not adequately resemble or predict the behaviour observed in the experiments. New models were developed for the first two coarsening mechanisms and predict the coarsening rate with very good agreement. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409005655

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