Abstract Mechanisms governing thermal stability of nanocrystalline metal alloys have typically been classified as either “kinetic” or “thermodynamic”, although both should generally be expected to manifest at the same time and either act constructively, or compete. The aim of this work is to present a quantitative study of thermal stability in ball-milled Fe-Mg alloys with two concurrent stabilization mechanisms at play—grain boundary segregation and Zener pinning by oxide nanoparticles—to assess their relative potency and to explore the interplay between them. To that end, we studied the alloys' configuration and attendant thermal stability by varying their composition, annealing time, temperature and atmosphere. At the mesoscale, both grain growth and oxide evolution were tracked by in-situ annealing during x-ray diffraction, as well as by electron microscopy and atom probe tomography. At the nanoscale, the local grain boundary chemistry was also probed. We discuss our results, which lie between the expectations from each separate mechanism, in terms of two primary interactions them. These results also suggest a method to control both grain and oxide precipitate size within a unified framework, and thus helps elaborate the design space for nanocrystalline alloys.

中文翻译：

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纳米晶铁镁合金热力学和动力学稳定机制之间的相互作用

摘要 控制纳米晶金属合金热稳定性的机制通常被归类为“动力学”或“热力学”，尽管两者通常应该同时出现，并且要么建设性地起作用，要么相互竞争。这项工作的目的是对球磨的 Fe-Mg 合金的热稳定性进行定量研究，同时有两种稳定机制在起作用——晶界偏析和氧化物纳米粒子的齐纳钉扎——以评估它们的相对效力并探索相互作用它们之间。为此，我们通过改变合金的成分、退火时间、温度和气氛来研究合金的配置和随之而来的热稳定性。在中尺度上，通过 X 射线衍射过程中的原位退火跟踪晶粒生长和氧化物演化，以及电子显微镜和原子探针断层扫描。在纳米尺度上，还探测了局部晶界化学。我们讨论了我们的结果，这些结果介于每个独立机制的期望之间，就两个主要相互作用而言。这些结果还提出了一种在统一框架内控制晶粒和氧化物沉淀尺寸的方法，从而有助于详细说明纳米晶合金的设计空间。