Evolution of a mushy zone in a static temperature gradient using a volume average approach
Evolution of a mushy zone in a static temperature gradient using a volume average approach
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DOI：
10.1016/j.actamat.2017.09.011
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发表时间：
2017-12
期刊：
影响因子：
9.4
通讯作者：
André Phillion;M. Založnik;I. Spindler;N. Pinter;C. Aledo;Georges;Salloum-Abou-Jaoude;Henri Nguyen Thi;G. Reinhart;Guillaume;Boussinot;M. Apel
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文献类型：
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作者：
André Phillion;M. Založnik;I. Spindler;N. Pinter;C. Aledo;Georges;Salloum-Abou-Jaoude;Henri Nguyen Thi;G. Reinhart;Guillaume;Boussinot;M. Apel
本文提出了一个体积平均模型来研究在静态温度梯度下半固态糊状区向平面固/液界面的转变。该模型模拟了糊状区动力学的主要现象，包括溶质在枝晶间和本体液体中的扩散、糊状区底部和顶部的固液界面和糊状液边界的迁移以及凝固。固-液界面的运动是通过进行固体和糊状区之间的微观溶质平衡来解析确定的。糊状-液体边界的运动更为复杂，因为它由具有快速变化的宏观性质的糊状和大体积液体区域之间的过渡组成。为了模拟这种运动，开发了一种控制体积，其特征在于溶质浓度的连续性以及液体分数和溶质浓度梯度的跳跃。体积平均模型已经通过与先前的原位X射线照相测量[1]和Al-Cu合金中的Mushy-to-plane转变的相场模拟[2]进行比较而得到验证。一个非常好的相似性之间所观察到的实验和相场动力学与这个新的模型，即使所描述的系统是只有一维。然而，为了模拟原位X射线研究中发生的对流溶质输运，需要增加散装液体中的溶质扩散系数。这种新模型将有助于模拟各种自然和工程过程。
A volume average model to study the transition of a semi-solid mushy zone to a planar solid/liquid interface in a static temperature gradient is presented. This model simulates the principal phenomena governing mushy zone dynamics including solute diffusion in the interdendritic and bulk liquids, migration of both the solid-liquid interface and the mushy-liquid boundary at the bottom and top of the mushy zone, and solidification.The motion of the solid-liquid interface is determined analytically by performing a microscopic solute balance between the solid and mushy zones. The motion of the mushy-liquid boundary is more complex as it consists of a transition between the mushy and bulk liquid zones with rapidly changing macroscopic properties. In order to simulate this motion, a control volume characterized by continuity in the solute concentration and a jump in both the liquid fraction and the solute concentration gradient was developed.The volume average model has been validated by comparison against prior in-situ X-ray radiography measurements [1], and phase-field simulations [2] of the mushy-to-planar transition in an Al-Cu alloy. A very good similarity was achieved between the observed experimental and phase-field dynamics with this new model even though the described system was only one-dimensional. However, an augmentation of the solute diffusion coefficient in the bulk liquid was required in order to mimic the convective solute transport occurring in the in situ X-ray study. This new model will be useful for simulating a wide range of natural and engineering processes.