DECLIC Scientific Program - Directional Solidification
- Paper number
IAC-06-A2.P.05
- Author
Mr. Bernard Billia, Faculté de Saint Jérome , France
- Year
2006
- Abstract
Authors: Cédric Weiss, Nathalie Bergeon, Nathalie Mangelinck, Bernard Billia
L2MP, UMR CNRS 6137, Université Paul Cézanne, Faculté de Saint Jérome, 13397 Marseille Cedex 20, France, nathalie.bergeon@L2MP.fr
The solidification microstructure, which controls materials properties, forms in the dynamical growth process so that live observation of its building is needed. Earth experiments point out interactions with buoyancy-driven fluid flow. Benchmark experiments under low gravity are thus planned using the Directional Solidification Insert in the DECLIC facility of CNES on ISS (MISOL3D - MIcrostructures de SOLidification 3D – project). The DSI is dedicated to the characterization by optical methods of the solid-liquid interface morphology on transparent systems that freeze like metals. The sample, contained in a glass tube, is solidified by pulling it down into the cold zone of a Bridgman furnace. The precise data on cellular/dendritic solidification under diffusion transport will be timely for the critical assessment of the numerical predictions by phase-field modelling. Here, recent prominent 1g results on dilute succinonitrile alloys are presented.
First, cell gliding from a circular source on the periphery to a central sink is analyzed. Due to the preferential evacuation of the solidification latent heat through the crucible, the interface is concave and, as cells grow perpendicular to the solid-liquid interface, the cell tip velocity has a radial component. Experimental data and theoretical curves both show a decrease of the advection velocity from the source to the sink. The misfit is attributed to fluid flow parallel to the cellular interface inducing tilting of the growth direction downstream.
Second, dynamical exchanges between singlets, doublets and other multiplets are observed in <100>-oriented dendritic directional solidification. A regular dendrite transforms into a multiplet through tip splitting instability. Conversely, a multiplet evolves into a lower-order multiplet, or back to a regular dendrite, by overgrowth/advection of some of its tips. The dendritic pattern does not reach a steady state but evolves continuously. The more “chaotic” the array dynamics the more numerous and more changing the multiplets.
Cédric Weiss, Nathalie Bergeon, Nathalie Mangelinck, Bernard Billia, L2MP, UMR CNRS 6137, Université Paul Cézanne, Faculté de Saint Jérome, 13397 Marseille Cedex 20, France, nathalie.bergeon@L2MP.fr
- Abstract document
- Manuscript document
IAC-06-A2.P.05.pdf (🔒 authorized access only).
To get the manuscript, please contact IAF Secretariat.