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Interface kinetics in phase field models: isothermal transformations in binary alloys and steps dynamics in molecular-beam-epitaxy

机译:相场模型中的界面动力学:等温变换   分子束外延中的二元合金和步骤动力学

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摘要

We present a unified description of interface kinetic effects in phase fieldmodels for isothermal transformations in binary alloys and steps dynamics inmolecular-beam-epitaxy. The phase field equations of motion incorporate akinetic cross-coupling between the phase field and the concentration field.This cross coupling generalizes the phenomenology of kinetic effects and wasomitted until recently in classical phase field models. We derive generalexpressions (independent of the details of the phase field model) for thekinetic coefficients within the corresponding macroscopic approach using aphysically motivated reduction procedure. The latter is equivalent to theso-called thin interface limit but is technically simpler. It involves thecalculation of the effective dissipation that can be ascribed to the interfacein the phase field model. We discuss in details the possibility of a nonpositive definite matrix of kinetic coefficients, i.e. a negative effectiveinterface dissipation, although being in the range of stability of theunderlying phase field model. Numerically, we study the step-bunchinginstability in molecular-beam-epitaxy due to the Ehrlich-Schwoebel effect,present in our model due to the cross-coupling. Using the reduction procedurewe compare the results of the phase field simulations with the analyticalpredictions of the macroscopic approach.
机译:我们在二元合金的等温转变的相场模型中给出界面动力学效应的统一描述,并给出分子束外延的阶跃动力学。运动的相场方程包含了相场和浓度场之间的运动交叉耦合,这种交叉耦合概括了动力学效应的现象学,直到最近在经典的相场模型中才被忽略。我们使用运动学上的简化程序,在相应的宏观方法内,得出了运动系数的一般表达式(与相场模型的细节无关)。后者等效于所谓的瘦接口限制,但在技术上更简单。它涉及可归因于相场模型中的界面的有效耗散的计算。我们详细讨论了动力学系数的非正定矩阵的可能性,即负有效界面耗散,尽管处于基础相场模型的稳定性范围内。在数值上,由于交叉耦合,我们研究了由于Ehrlich-Schwoebel效应而引起的分子束外延中的阶跃成束不稳定性。使用简化程序,我们将相场模拟的结果与宏观方法的分析预测进行了比较。

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  • 作者

    Boussinot, G.; Brener, Efim A.;

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  • 年度 2014
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  • 原文格式 PDF
  • 正文语种 {"code":"en","name":"English","id":9}
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