Three-dimensional phase-field simulation of micropore formation during solidification: Morphological analysis and pinching effect

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• 作者：H. Meidani^a ; ^{hossein.meidani@a3.epfl.ch} ; J.-L. Desbiolles^a ; A. Jacot^a ; ^b ; M. Rappaz^a
• 关键词：Casting defects ; Porosity ; Solidification microstructure ; Simulation ; Phase field modeling
• 刊名：Acta Materialia
• 出版年：2012
• 期刊代码：1_13596454
• 类别：ms
• 出版时间：April, 2012
• 卷：60
• 期：6-7
• 页码：2518-2527
• 文件大小：886 K

摘要

A three-dimensional (3-D) multiphase-field model has been developed in order to study the formation of a micropore constrained to grow in a solid network (i.e. pinching effect). The model accounts for the pressure difference due to capillarity between liquid and gas, the equilibrium condition at triple (solid-liquid-pore) lines, and the partitioning and diffusion of dissolved gases such as hydrogen. From the predicted 3-D morphology of the pore, entities such as the interfacial shape distribution are plotted and analyzed. It is shown that the mean curvature of the pore-liquid surface, and thus also the pressure inside the pore, is uniform. The results are then compared with analytical pinching models. While predicting a similar trend, analytical models tend to underestimate the pore curvature at high solid fractions. Despite the complex morphology of pores reconstructed using high-resolution X-ray tomography, the present phase-field results suggest that a simple pinching model based on a spherical tip growing in between remaining liquid channels is a fairly good approximation.