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arXiv 1105.1670cond-mat.mtrl-scicond-mat.stat-mech
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基于巨势泛函的合金凝固相场模型统一推导

Unified derivation of phase-field models for alloy solidification from a grand-potential functional

Mathis Plapp

摘要:

在文献中,对于合金凝固问题,可以找到两种完全不同的相场公式:第一种是假设扩散界面上的材料处于固液之间的中间状态,具有独特的局部成分。在第二种情况下,界面被视为两相的混合物,每一个保留其宏观性质,并为每个阶段引入一个单独的浓度场。它在这里示出,这两种类型的模型可以通过标准的变分过程,如果一个大的潜在功能是作为一个出发点,而不是一个自由能功能。动力学变量是化学势而不是组分。在这个框架中,可以建立与纯物质凝固的相场模型的完全类比。这种类比,然后利用制定定量相场模型的合金与任意相图。数值模拟结果表明,该方法的精度与不同的界面厚度。

英文摘要:

In the literature, two quite different phase-field formulations for the problem of alloy solidification can be found. In the first, the material in the diffuse interfaces is assumed to be in an intermediate state between solid and liquid, with a unique local composition. In the second, the interface is seen as a mixture of two phases that each retain their macroscopic properties, and a separate concentration field for each phase is introduced. It is shown here that both types of models can be obtained by the standard variational procedure if a grand-potential functional is used as a starting point instead of a free-energy functional. The dynamical variable is then the chemical potential instead of the composition. In this framework, a complete analogy with phase-field models for the solidification of a pure substance can be established. This analogy is then exploited to formulate quantitative phase-field models for alloys with arbitrary phase diagrams. The precision of the method is illustrated by numerical simulations with varying interface thickness.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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