Abstract Nanoscale interdiffusion at the heterophase interfaces is the elementary process that controls solid-solid phase transformations and intermixing in multilayers. Here, we provide a direct experimental proof that the nanoscale multiphase interdiffusion is controlled by the interface mobility. We observed the anisotropic diffusion intermixing in Au–Fe bimetallic nanowhiskers, where the diffusion penetration depth of Fe into single crystalline Au nanowhisker across the incoherent Au–Fe interface was much greater than across its coherent counterpart. By applying a simple kinetic model to the results of diffusion measurements, we obtained the absolute values of mobilities of coherent and incoherent Fe-Au interfaces, and the Arrhenius parameters describing their temperature dependence. Atomic resolution scanning transmission electron microscopy confirmed that the lower mobility of the coherent interface is associated with the difficulties of the nucleation of interface disconnections. We proposed that the sluggish movement of the latter represents a kinetic “bottleneck” which determines the rate of intermixing. Our results indicate that the anisotropy of interface mobilities is a leading factor determining the anisotropic shape of precipitates formed in many heterogeneous solid-solid phase transformations.

中文翻译：

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界面迁移率控制的双金属 Au-Fe 纳米晶须的相互扩散

摘要 异相界面处的纳米级相互扩散是控制固-固相转变和多层混合的基本过程。在这里，我们提供了一个直接的实验证明，即纳米级多相相互扩散是由界面迁移率控制的。我们观察到 Au-Fe 双金属纳米晶须中的各向异性扩散混合，其中 Fe 穿过非相干 Au-Fe 界面进入单晶 Au 纳米晶须的扩散渗透深度远大于其相干对应物。通过将简单的动力学模型应用于扩散测量的结果，我们获得了相干和非相干 Fe-Au 界面迁移率的绝对值，以及描述其温度依赖性的 Arrhenius 参数。原子分辨率扫描透射电子显微镜证实，相干界面的较低迁移率与界面断开成核的困难有关。我们提出后者的缓慢运动代表了决定混合速率的动力学“瓶颈”。我们的结果表明，界面迁移率的各向异性是决定在许多非均相固-固相转变中形成的沉淀物各向异性形状的主要因素。