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Etude expérimentale par observation in-situ de la dynamique non-linéaire des fronts de solidification directionnelle eutectiques fibreux de l'alliage transparent succinonitrile-camphre

Abstract : We present an experimental investigation of the dynamics of fibrous non-faceted eutectic directional-solidification structures in semi-bulk samples. A transparent succinonitrile-d,camphor alloy is used. The whole structure is followed in real time using a new optical setup, which permits to observe the growth front in oblique view with a micronic resolution. The symmetry of the fibrous structure is basically hexagonal. We show that a residual curvature of the isotherms causes a constant stretching of the structure, and leads to a permanent regime near the upper stability threshold (branching instability). Defects are continually generated by the branching. We also show that the lower stability threshold (fibers elimination) coincides with the Eckhaus instability threshold, as measured in thin-sample experiments. We also studied other instabilities of the fibrous structure (oscillation, ovalization).
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https://tel.archives-ouvertes.fr/tel-00492990
Contributor : Mikael Perrut Connect in order to contact the contributor
Submitted on : Thursday, June 17, 2010 - 3:27:57 PM
Last modification on : Wednesday, December 9, 2020 - 3:05:25 PM
Long-term archiving on: : Monday, September 20, 2010 - 5:34:08 PM

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  • HAL Id : tel-00492990, version 1

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Mikael Perrut. Etude expérimentale par observation in-situ de la dynamique non-linéaire des fronts de solidification directionnelle eutectiques fibreux de l'alliage transparent succinonitrile-camphre. Physique [physics]. Université Pierre et Marie Curie - Paris VI, 2007. Français. ⟨tel-00492990⟩

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