コヒーレントX線により金属材料内部のナノ構造変化を「動画」で観察～高性能材料開発に繋がる新手法～

2025-09-16 東北大学

東北大学・理研・北陸先端大などの研究チームは、コヒーレントX線回折とデータ科学的手法を統合し、金属材料内部のナノ構造変化を“動画”として可視化する新手法を開発した。軽量高強度のマグネシウム合金を加熱し、析出物の生成から成長、粗大化までをナノ～マイクロメートル、秒～時間スケールで追跡することに成功。個々の析出物の成長速度や方向を定量評価したのは初めてである。本手法は金属に限らず高分子や触媒・電池材料にも応用可能で、高性能材料開発に資する普遍的フレームワークとなる。成果はPNASに掲載された。

図1. Mg合金の加熱その場観察を実施したコヒーレントX線回折実験の模式図

＜関連情報＞

マルチモーダルコヒーレントX線回折イメージングによる合金メゾ構造ダイナミクスの時空間マッピング Spatiotemporal mapping of alloy mesostructure dynamics via multimodal coherent X-ray diffraction imaging

Shuntaro Takazawa, Kakeru Ninomiya, Minh-Quyet Ha, +11 , and Yukio Takahashi
Proceedings of the National Academy of Sciences Published:September 17, 2025
DOI:https://doi.org/10.1073/pnas.2513369122

Significance

Understanding the mesoscale structural dynamics of precipitation-strengthened alloys is critically important for designing high-performance materials. In this study, we present a multimodal coherent X-ray diffraction imaging framework for spatiotemporal mapping of microstructural evolution during thermal processing. Using this method, we elucidate the nucleation, growth, and coarsening of nanoscale precipitates in a Mg-Zn-Gd alloy during isothermal annealing at 700 K. Our approach integrates ptychography, dynamic coherent diffraction imaging, and X-ray photon correlation spectroscopy to provide complementary insights across multiple spatial and temporal scales. Additionally, optical flow analysis enables quantitative characterization of transformation kinetics. Our methodology offers a robust framework for investigating dynamic phenomena in diverse material systems, including metals, polymers, and functional nanomaterials, under realistic thermal or mechanical conditions.

Abstract

Understanding mesoscale structural dynamics of precipitation-strengthened alloys is essential for optimizing the mechanical performances of these alloys. Herein, we establish a multimodal coherent X-ray diffraction imaging framework for spatiotemporal mapping of mesoscale structural dynamics in precipitation-strengthened alloys. As a demonstrative application, we visualized the structural evolution in Mg₉₇Zn₁Gd₂ during isothermal annealing at 700 K, revealing real-time dynamics of nucleation, growth, and coarsening. Ptychographic reconstruction enabled imaging of microstructural transformations across a wide field of view (~100 μm²) with temporal resolution spanning several hours. We observed decomposition of (Mg, Zn)₃Gd and concurrent precipitation and coarsening of long-period stacking ordered phases. To resolve local dynamics at finer spatiotemporal scales, we combined dynamic coherent diffraction imaging with X-ray photon correlation spectroscopy, targeting selected regions (~10 μm²) with time resolution down to tens of seconds. This approach revealed the rapid formation of nanoscale precipitates within 10 s after heating, followed by coarsening over several hundred seconds. Additionally, we applied optical flow analysis—a computational method to track motion patterns—to visualize and quantify the nucleation, growth, and coarsening kinetics. The abovementioned findings demonstrate the capability of in situ coherent X-ray techniques to acquire the real-time evolutions of mesoscale structures in complex materials. Our methodology offers a robust framework for investigating dynamic phenomena in diverse material systems, including metals, polymers, and functional nanomaterials, under realistic thermal or mechanical conditions.