Abstract Metallic glasses, formed from highly undercooled liquids, are ideal systems for fine tuning microstructures. The structure of the glass and the slow kinetics of devitrification provide many possible reaction pathways to form both stable and metastable phases. The Al-RE system is a prime example with many metastable-to-metastable phase transitions. Here we report observation of the transition from e-Al60Sm11 to π-Al5Sm and fcc-Al using multiple ex-situ and in-situ methods. Ex-situ transmission electron microscope (TEM) observation demonstrates that the decomposition of e-Al60Sm11 propagates with nearly identical spacing between fcc-Al and π-Al5Sm during isothermal annealing. In-situ high energy wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS) methods were employed along with the DSC demonstrate the multiple phase evolution with temperature and time. A novel SAXS analysis approach is presented and validated by ex-situ TEM analysis. These results suggest that nearly monodispersed Al-nanocrystals forms at a constant rate during an isothermal annealing. Both in-situ and ex-situ observations elucidate the transition from e-Al60Sm11 to π-Al5Sm and fcc-Al as an eutectoid reaction.

中文翻译：

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通过原位X射线散射和异位透射电子显微镜监测Al-Sm合金中亚稳相的共析分解过程

摘要 由高度过冷液体形成的金属玻璃是微调微结构的理想系统。玻璃的结构和缓慢的反玻璃化动力学提供了许多可能的反应途径来形成稳定相和亚稳定相。Al-RE 系统是具有许多亚稳态到亚稳态相变的主要例子。在这里，我们报告了使用多种非原位和原位方法观察从 e-Al60Sm11 到 π-Al5Sm 和 fcc-Al 的转变。异位透射电子显微镜 (TEM) 观察表明，在等温退火过程中，e-Al60Sm11 的分解以 fcc-Al 和 π-Al5Sm 之间几乎相同的间距传播。原位高能广角 X 射线衍射 (WAXD) 和小角 X 射线散射 (SAXS) 方法与 DSC 一起使用，证明了随温度和时间的多相演变。提出了一种新的 SAXS 分析方法，并通过原位 TEM 分析进行了验证。这些结果表明，在等温退火过程中，几乎单分散的铝纳米晶体以恒定速率形成。原位和非原位观察都阐明了从 e-Al60Sm11 到 π-Al5Sm 和 fcc-Al 作为共析反应的转变。