Simulation of Solidification and Convection of NH₄Cl-H₂O Solution in a Water-Cooled Copper Mold

Abstract:

The convection pattern and the evolution of mushy zone, temperature and solidification structure are measured during solidification of NH₄Cl-70%H₂O solution in a water-cooled copper mold with transparent sidewalls. The natural convection and crystal sedimentation are measured via Particle Image Velocimetry (PIV) technique. This experiment is simulated using a 5-phase mixed columnar-equiaxed solidification model proposed by current authors [Comp. Mater. Sci. 50 (2010) 32-4]. The 5 phases comprise the extradendritic melt, the solid dendrite and interdendritic melt inside the equiaxed grains, the solid dendrite and interdendritic melt inside the columnar grains. Melt convection and crystal sedimentation are considered. It is demonstrated that the experimentally observed flow patterns and the solidification structure can be qualitatively reproduced. Reasons for the quantitative deviation between the simulation and experiment are discussed. Analysis of the modeling results in details and improvement of the calculation accuracy will be in a subsequent step.

• Periodical: Materials Science Forum (Volumes 790-791)
• Pages: 247-252
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.790-791.247
• Online since: May 2014
• Authors: Mahmoud Ahmadein*, Meng Huai Wu, Mehaela Stefan Kharicha, Abdella Kharicha, Andreas Ludwig
• Keywords: Columnar-To-Equiaxed Transition, Convection, Crystal Sedimentation, Macrosegregation, Modeling, Solidification

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