We employed a regular solution-type model to describe the equilibrium segregation of solute atoms on the external surface and at the film–substrate interface in the ultrathin single-crystalline films of binary metal alloys attached to an inert substrate. The finite size of the system, the interlayer interactions in the film and the heteroepitaxial strain in the film were taken into account. We demonstrated that the homogeneous heteroeptiaxial strain in the film affects the surface and interface segregation of solute atoms only in the case when the value of coherency strain parameter (describing the relative change of alloy lattice parameter upon addition of solutes) in the surface and interface layers is different from its value in the rest of the films. The developed model was applied to the Ni(Au) thin films deposited on sapphire substrate. The quantitative agreement between the model predictions and recent experimental data on interface segregation of Au could be achieved by assuming that the film is heteroepitaxially compressed.

中文翻译：

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应力对惰性基体上合金薄膜表面和界面偏析的影响

我们采用常规溶液型模型来描述附着在惰性基材上的二元金属合金超薄单晶薄膜中溶质原子在外表面和薄膜 - 基材界面处的平衡偏析。考虑了系统的有限尺寸、薄膜中的层间相互作用和薄膜中的异质外延应变。我们证明了薄膜中的均匀异质外延应变仅在表面和界面层中的相干应变参数值（描述添加溶质后合金晶格参数的相对变化）的情况下影响溶质原子的表面和界面偏析与它在其他电影中的价值不同。开发的模型应用于沉积在蓝宝石衬底上的 Ni(Au) 薄膜。