Phase-field simulation of micropores constrained by the dendritic network during solidification
Phase-field simulation of micropores constrained by the dendritic network during solidification
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DOI：
10.1016/j.actamat.2011.01.043
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发表时间：
2011-05-01
期刊：
影响因子：
9.4
通讯作者：
Jacot, A.
中科院分区：
文献类型：
--
作者：
Meidani, H.;Jacot, A.
发展了一个相场模型来描述受树枝状固体网络约束的气孔的形态，并强迫其采用复杂的非球形形状。采用考虑气液压差的多相场方法计算了固、液、气三相的分布。该模型考虑了界面上溶解气体的分配、固/液、液/气和气/固界面上的气体扩散和毛细管力。利用该模型研究了枝晶臂间距(DAS)和固相分数对气孔状态的影响。计算表明，在狭窄的液体通道中，受约束的孔隙比不受约束的孔隙具有更高的平均曲率、更大的压力和更小的体积。与简单几何模型的比较表明，分析方法显示出良好的趋势，但往往低估了孔曲率，特别是在高固相分数时，孔必须穿透稀薄的液体通道。对于跨度大于平均DAS的孔，模拟表明曲率半径可以在两个限制之间变化，这两个限制是由孔扩展所需通过的最窄部分的大小和树枝间液体中可以容纳的最大球体给出的。因此，孔曲率是DAS、固相分数、氢含量和液体通道宽度的统计变化的复杂的非单调函数。(C)2011 Acta Materialia Inc.由爱思唯尔有限公司出版。保留所有权利。
A phase-field model has been developed to describe the morphology of pores constrained by a dendritic solid network, and are forced to adopt complex non-spherical shapes. The distribution of the solid, liquid and gas phases was calculated with a multiphase-field approach which accounts for the pressure difference between the liquid and the gas. The model considers the partitioning of the dissolved gas at interfaces, gas diffusion and capillary forces at the solid/liquid, liquid/gas and gas/solid interfaces. The model was used to study the influence of the dendrite arm spacing (DAS) and the solid fraction on the state of a pore. The calculations show that a pore constrained to grow in a narrow liquid channel exhibits a substantially higher mean curvature, a larger pressure and a smaller volume than an unconstrained pore. Comparisons with simple geometrical models indicate that analytical approaches show a good trend but tend to underestimate the pore curvature, in particular at high solid fractions, where pores have to penetrate the thin liquid channels. For pores spanning over distances larger than the average DAS, the simulations showed that the radius of curvature can vary between two limits, which are given by the size of the narrowest section that the pore needs to pass in order to expand and by the largest sphere that can be fitted in the interdendritic liquid. The pore curvature is therefore a complex non-monotonic function of the DAS, the solid fraction, the hydrogen content and statistical variations of the liquid channel width. (C) 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.