Morphological Transitions of Shallow Cells during Thin-Film Solidification of an Alloy: Phase Field Modeling & Experimental Observation
Journal
Journal of the Chinese Institute of Chemical Engineers
Journal Volume
36
Journal Issue
4
Pages
311-320
Date Issued
2005
Author(s)
Abstract
The morphological transitions of shallow cells near the onset of Mullins-Sekerka instability during the thin-film directional solidification of a succinonitrile/acetone alloy have been simulated quantitatively by means of phase field modeling for the first time. Long time/length scale experiments at a constant pulling speed were performed for the purpose of comparison. The simulation results show good agreement with classic theories in the planar and λ(subscript c)↔λ(subscript c)/2 cellular bifurcation regions, where λ(subscript c) is the critical wavelength. At a higher pulling speed, V, an anti-trapping current was introduced to maintain the local equilibrium, and the region for Vλ^2~constant was found. Finally, multiplets appeared when λ was close to λ(subscript c)/4. In the experiments, due to slow solute accumulation in the molten zone, morphological transitions were also revealed. Some interesting nonlinear phenomena, such as tip splitting, coarsening, pinch-off, and asymmetric cells, were also confirmed through both simulations and experiments.
Type
journal article
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