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Evolution of a mushy zone in a static temperature gradient using a volume average approach
Acta Materialia ( IF 9.4 ) Pub Date : 2017-12-01 , DOI: 10.1016/j.actamat.2017.09.011
A.B. Phillion , M. Založnik , I. Spindler , N. Pinter , C.-A. Aledo , G. Salloum-Abou-Jaoude , H. Nguyen Thi , G. Reinhart , G. Boussinot , M. Apel , H. Combeau

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.

中文翻译:

使用体积平均方法在静态温度梯度中的糊状区域的演变

提出了一种体积平均模型,用于研究静态温度梯度下半固体糊状区向平面固/液界面的转变。该模型模拟了控制糊状区动力学的主要现象,包括枝晶间和本体液体中的溶质扩散、糊状区底部和顶部的固-液界面和糊状-液体边界的迁移以及凝固。固液界面的运动是通过在固体和糊状区域之间进行微观溶质平衡来分析确定的。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特性的糊状液体区域和块状液体区域之间的过渡组成。为了模拟这种运动,开发了一个控制体积,其特征是溶质浓度的连续性以及液体分数和溶质浓度梯度的跳跃。体积平均模型已通过与先前的原位 X 射线射线照相测量 [1] 和 Al-Cu 合金糊状到平面转变的相场模拟 [2] 进行比较而得到验证。尽管所描述的系统只是一维的,但在观察到的实验和相场动力学之间实现了非常好的相似性。然而,为了模拟原位 X 射线研究中发生的对流溶质传输,需要增加大量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。
更新日期:2017-12-01
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