in Titre de série : | Acta metallurgica, Vol.32 No.6 | Titre : | Theory of cellular solidification of binary alloys with applications to succinonitrile-salol | Type de document : | articles et extraits | Auteurs : | D. Venugopalan, Auteur ; J. S. Kirkaldy, Auteur | Année de publication : | 1984 | Importance : | p.893-906 | Langues : | Français (fre) | Mots-clés : | alloys interface phenomena organic compounds solidification Widmanstatten structure | Résumé : | Offers a nonlocal equilibrium model for stable cell formation as an alternative to the standard but unsuccessful local equilibrium models. Recognizing from the observations that the morphology in steady state cellular solidification of alloy single crystals belongs to the family of Widmanstatten figures, a Zener-Hillert type model has been developed and applied to experiments on succinonitrile-salol. In the inverse Widmanstatten pattern generated and observed under controlled boundary conditions the interface curvature is such that strong capillary effects appear only at the trailing roots of the cells. Since the roots have dimensions <<1 mu m the temperature-composition diagram possesses a sharp low temperature jog towards higher compositions. Thus, since neither the temperature nor liquid diffusion profiles can sustain a matching singularity, the liquid-solid interface cannot everywhere exist in local equilibrium. Concomitantly, there must exist stabilizing effects associated with crystallographic or kinetic anisotropy acting at the cell walls if these liquid-solid Widmanstatten figures are to be sustained
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in Acta metallurgica, Vol.32 No.6. Theory of cellular solidification of binary alloys with applications to succinonitrile-salol [articles et extraits] / D. Venugopalan, Auteur ; J. S. Kirkaldy, Auteur . - 1984 . - p.893-906. Langues : Français ( fre) Mots-clés : | alloys interface phenomena organic compounds solidification Widmanstatten structure | Résumé : | Offers a nonlocal equilibrium model for stable cell formation as an alternative to the standard but unsuccessful local equilibrium models. Recognizing from the observations that the morphology in steady state cellular solidification of alloy single crystals belongs to the family of Widmanstatten figures, a Zener-Hillert type model has been developed and applied to experiments on succinonitrile-salol. In the inverse Widmanstatten pattern generated and observed under controlled boundary conditions the interface curvature is such that strong capillary effects appear only at the trailing roots of the cells. Since the roots have dimensions <<1 mu m the temperature-composition diagram possesses a sharp low temperature jog towards higher compositions. Thus, since neither the temperature nor liquid diffusion profiles can sustain a matching singularity, the liquid-solid interface cannot everywhere exist in local equilibrium. Concomitantly, there must exist stabilizing effects associated with crystallographic or kinetic anisotropy acting at the cell walls if these liquid-solid Widmanstatten figures are to be sustained
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