Abstract It has been established that, under certain conditions, the flat interphase boundary separating two ternary phases can be become morphologically unstable during the interdiffusion process. By a direct analogy with the constitutional supercooling criterion in alloy solidification, it has been proposed that the instability in ternary two-phase diffusion couples occurs when either or both diffusion paths enter into the two-phase region of the phase diagram. In this work a linear stability analysis of the diffusion problem is performed and the conditions for stability are expressed in terms of the diffusion coefficients, the slopes of the concentration profiles at the interface, and the system free energy as a function of composition. Through the use of a model ternary system, various examples of unstable interfaces are illustrated. It is found that the crossing of a diffusion path into the two-phase coexistence region is a necessary, but not sufficient condition for instability.

中文翻译：

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三元两相扩散偶的形态稳定性分析

摘要 已经确定，在一定条件下，分隔两个三元相的平坦相界面在相互扩散过程中会变得形态不稳定。通过与合金凝固中的组成过冷准则直接类比，有人提出，当一个或两个扩散路径进入相图的两相区域时，三元两相扩散偶的不稳定性就会发生。在这项工作中，对扩散问题进行了线性稳定性分析，稳定性条件用扩散系数、界面处浓度分布的斜率和作为组成函数的系统自由能表示。通过使用模型三元系统，说明了不稳定界面的各种示例。