Supervisor : Silvère AKAMATSU
Contact : akamatsu@insp.jussieu.fr, Tel : 01 44 27 63 99
Funding : CNRS - Sorbonne Université
keywords : Internship M2
Gratification : Oui
Team(s) internship page(s) : Chemical Physics and Dynamics of Surfaces  
Internship description

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Keywords: solidification, melting, in situ experiments, microgravity, pattern formation

Scientific description:
Melting is merely the reverse of solidification, but the two processes give rise to contrasting
pattern formation phenomena. This stems, in particular, from the fact that the melting
dynamics of a material is strongly sensitive to the microstructures that were previously frozen
during solidification. This largely unexplored problem is attracting new attention in
relationship to the development of additive manufacturing techniques that involves partial
melting and solidification stages during the elaboration of complex metal alloy pieces. To this
respect, eutectic composite alloys with two-phase microstructures are especially interesting.
For a deeper understanding of the physical mechanisms, in situ experiments in well-controlled
conditions with real-time optical imaging of the melting front are needed. We propose an
investigation of the directional melting in a fixed temperature gradient of a model transparent
alloy in thin (10-μm thick) samples. In that geometry, the dynamics of the system in essentially
2D, thus facilitating the acquisition and the analysis of the images during both steady-state
and transient regimes. The observations can then be compared to the available theory, based
on the coupling of the motion of the solid-liquid interface with the diffusion of chemical
species. Challenging questions relative to the relevant scaling quantities should be addressed.
This study is part of the preparation of an upcoming science-in-microgravity experimental
program (ESA) onboard the ISS.

Techniques/methods in use: optical microscopy, solidification, image analysis
Applicant skills: materials science
Internship location: INSP, Campus Jussieu
Possibility for a Doctoral thesis: Y (possibly ½ grant CNES) ; codir. M. Plapp, Ec. Polytechnique
(phase-field simulations).