Coherence of dendritic sidebranching in directional solidification

• Published in: Europhysics letters Vol. 77; no. 4; pp. 46001 - 46001 (5)
• Main Authors: Georgelin, M, Bodea, S, Pocheau, A
• Format: Journal Article
• Language: English
• Published: IOP Publishing 01.02.2007; EDP Sciences; European Physical Society / EDP Sciences / Società Italiana di Fisica / IOP Publishing
• Subjects: 68.70.+w; 81.10.Aj; 81.30.Fb; Engineering Sciences; Fluid mechanics; Fluids mechanics; Mechanics; Physics
• ISSN: 0295-5075; 1286-4854
• DOI: 10.1209/0295-5075/77/46001

Dendrites stand as the main solidification microstructure of dilute alloys. They are characterized by repetitive emissions of sidebranches on a growing needle form whose regularity conditions the solid structure at micrometric scales. We experimentally evidence here the coherence of this dendritic sidebranching in directional solidification. Sidebranches are found to be emitted by bursts of typically four to fifteen branches. The correlation functions of the signal extracted by cuts of the interface profile reveals a burst distribution that is uncorrelated in length, in time, and in phase of sidebranching, but a sidebranch distribution that is remarkably coherent inside each burst. The former feature may explain the appearance of uncorrelated sidebranching in former experiments and the latter feature reveals a puzzling self-organization of dendrites. Both their origins and mechanisms remain to be understood.