J. Phys. I France
Volume 7, Numéro 10, October 1997
Page(s) 1259 - 1265
J. Phys. I France 7 (1997) 1259-1265
DOI: 10.1051/jp1:1997122

On Static and Dynamical Young's Condition at a Trijunction

C. Caroli1 and C. Misbah2

1  Groupe de Physique des Solides Unité associée au CNRS, Universités Paris 7 et 6, 2 Place Jussieu, 75005 Paris, France
2  Laboratoire de Spectrométrie Physique Unité associée au CNRS, Université Joseph Fourier, Grenoble I, BP 87, Saint-Martin d'Hères, 38402 Cedex, France

(Received 18 November 1996, revised 20 February 1997, accepted 10 June 1997)

Using a consistent purely kinetic model we show that Young's condition at a trijunction results from a chemical and not a mechanical equilibrium, as is often believed in the literature. In an out-of equilibrium situation this condition is altered in a way such that the triple point acquires an effective mobility. The order of magnitude of the mobility is fixed by a velocity scale $\tilde{V}_{\rm att}$ associated with chemical attachment at the interface, and not by the sound speed. While for ordinary eutectics $\tilde{V}_{\rm att}$ is large (except in rapid solidification experiments) in comparison to the growth speed, implying a quasi-instantaneous mobility, finite mobility effects should show up for faceted eutectics as well as for eutectoid transformations.

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