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Ignacio Maxime

Groupe Irrégularité

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+33 (0)1 69 33 47 17

The understanding of micro-structure development during eutectic alloy solidification is crucial for technological applications. It is also interesting from a fundamental point of view, because these systems are a wonderful example of pattern formation in dissipative dynamical system.

Up to now, the effects of the crystal anisotropy on the patterns and their evolution remains poorly understood. For sample compositions close to the eutectic point, the solid phase is a composite consisting of an array of lamallae. During solidification, there is a diffusive process which tends to homogenize the lamellar spacing. Recent directional solidification experiments in thin samples realized by the group of S. Akamatsu (INSP Paris) show that the anisotropy can modify, or even block, the homogenization process. Analytically, we have obtained an evolution equation equation for the solidification front which takes into account the anisotropy. We predict that the anisotropy changes both the thresholds and the diffusion coefficient which governs the evolution of the lamellar spacing. These predictions are compared to mesoscopic phase-field simulation.