Abstract We present a new approach for the quantitative study of high-temperature diffusion in compositionally complex superalloys on the nano-scale. As key element, the approach utilizes the γ/γ'-microstructure itself as intrinsic nano-diffusion-couple (NDC). By establishing equilibrium at one temperature followed by annealing at a different temperature, well-defined transient states are generated which are studied using STEM-EDXS. We demonstrate this approach for a multi-component superalloy of CMSX-4 type. The temporal evolution of element concentrations is consistently revealed for γ- and γ'-forming elements and is compared to diffusion simulations based on DICTRA. Excellent agreement is obtained for Ni, Co, and Cr whereas diffusion of Al and, in particular, Re lacks behind in experiment. Finally, it is demonstrated that transient states can also be captured by in situ TEM using chip-based heating devices. The NDC approach offers great opportunities for diffusion studies in compositionally complex superalloys and might be extended to other two-phase multi-component systems.

中文翻译：

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用于研究多组分高温合金中高温扩散的本征纳米扩散偶

摘要 我们提出了一种定量研究纳米级成分复杂高温合金高温扩散的新方法。作为关键要素，该方法利用 γ/γ'-微结构本身作为本征纳米扩散偶 (NDC)。通过在一个温度下建立平衡，然后在不同温度下退火，可以生成明确定义的瞬态，并使用 STEM-EDXS 进行研究。我们为 CMSX-4 类型的多组分高温合金演示了这种方法。γ-和γ'-形成元素的元素浓度随时间的演变一直被揭示，并与基于 DICTRA 的扩散模拟进行比较。Ni、Co 和 Cr 获得了极好的一致性，而 Al 的扩散，特别是 Re 的扩散在实验中缺乏。最后，已经证明，瞬态也可以通过使用基于芯片的加热设备的原位 TEM 来捕获。NDC 方法为成分复杂的高温合金的扩散研究提供了很好的机会，并且可能会扩展到其他两相多组分系统。