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On interatomic mixing and demixing phenomena in Cr-Fe: statistical-mechanical calculations based on composition-dependent interaction energy model

机译：Cr-Fe中原子间混合和解离现象的研究：基于成分相关的相互作用能模型的统计力学计算

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Variations of Fe(I 0 0) surface composition with Cr coverage at 53 K were evaluated by means of the "free-energy concentration expansion method" (FCEM). The calculations, complementing our previous study [Phys. Rev. B 65 (2002) 205404]. are based on four energetics models: composition-dependent (or independent) and surface-enhanced (or uniform) interactions. A linear dependence of the mixing enthalpy and of the corresponding effective interactions on temperature was taken into account. Numerical free-energy minimization showed that only the first of the four models, namely composition-dependent surface-enhanced interactions that change sign at similar to10% Cr, is consistent with scanning tunneling microscopy (STM) and Auger electron spectroscopy (AES) studies reported before. Effects of temperature on alloying at the Cr/Fe(l 0 0) surface are weak in the mixing region of low Cr concentrations, while for higher coverages the transition to Cr segregated/separated surface layer, induced by the mixing/demixing interaction reversal, is diminished considerably at elevated temperatures. Mixing/demixing effects related to the interaction change seem to be manifested also in model calculations of the bee part of the Cr-Fe bulk phase diagram. (C) 2003 Elsevier B.V. All rights reserved. [References: 19]
机译：通过“自由能浓度扩展法”（FCEM）评估了在53 K时具有Cr覆盖率的Fe（I 0 0）表面组成的变化。这些计算补充了我们先前的研究[Phys。版本B 65（2002）205404]。基于四种能量学模型：成分相关（或独立）和表面增强（或均匀）相互作用。考虑了混合焓和相应的有效相互作用对温度的线性依赖性。数值自由能最小化表明，只有四个模型中的第一个模型，即与成分有关的表面增强相互作用（在接近10％Cr时改变符号）与扫描隧道显微镜（STM）和俄歇电子能谱（AES）研究一致之前。在低Cr浓度的混合区域中，温度对Cr / Fe（l 0 0）表面合金化的影响较弱，而对于较高的覆盖率，则由于混合/脱脂相互作用的逆转而导致向Cr偏析/分离的表面层的转变，在高温下会大大降低。 Cr-Fe块体相图的蜜蜂部分的模型计算中似乎也显示了与相互作用变化相关的混合/去雾作用。 （C）2003 Elsevier B.V.保留所有权利。 [参考：19]

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