Atomic-scale observation of non-classical nucleation-mediated phase transformation in a titanium alloy

Two-phase titanium-based alloys are widely used in aerospace and biomedical applications, and they are obtained through phase transformations between a low-temperature hexagonal closed-packed alpha-phase and a high-temperature body-centred cubic beta-phase. Understanding how a new phase evolves from its parent phase is critical to controlling the transforming microstructures and thus material properties. Here, we report time-resolved experimental evidence, at sub-angstrom resolution, of a non-classically nucleated metastable phase that bridges the alpha-phase and the beta-phase, in a technologically important titanium-molybdenum alloy. We observed a nanosized and chemically ordered superstructure in the alpha-phase matrix; its composition, chemical order and crystal structure are all found to be different from both the parent and the product phases, but instigating a vanishingly low energy barrier for the transformation into the beta-phase. This latter phase transition can proceed instantly via vibrational switching when the molybdenum concentration in the superstructure exceeds a critical value. We expect that such a non-classical phase evolution mechanism is much more common than previously believed for solid-state transformations.

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Work Title Atomic-scale observation of non-classical nucleation-mediated phase transformation in a titanium alloy
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Open Access
Creators
  1. Xiaoqian Fu
  2. Xu-Dong Wang
  3. Beikai Zhao
  4. Qinghua Zhang
  5. Suyang Sun
  6. Jiang-Jing Wang
  7. Wei Zhang
  8. Lin Gu
  9. Yangsheng Zhang
  10. Wen-Zheng Zhang
  11. Wen Wen
  12. Ze Zhang
  13. Long-qing Chen
  14. Qian Yu
  15. En Ma
License In Copyright (Rights Reserved)
Work Type Article
Publisher
  1. Nature Materials
Publication Date 2022
Publisher Identifier (DOI)
  1. https://doi.org/10.1038/s41563-021-01144-7
Deposited August 11, 2022

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  • Added Atomic-scale observation of non-classical nucleation-mediated phase transformation in a titanium alloy.pdf
  • Updated License Show Changes
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  • Updated Acknowledgments Show Changes
    Acknowledgments
    • Author list: Xiaoqian Fu, Xu-Dong Wang, Beikai Zhao, Qinghua Zhang, Suyang Sun, Jiang-Jing Wang2 , Wei Zhang , Lin Gu  , Yangsheng Zhang, Wen-Zheng Zhang, Wen Wen , Ze Zhang, Long-qing Chen , Qian Yu  and En Ma
  • Updated Publisher, Publisher Identifier (DOI), Description, and 1 more Show Changes
    Publisher
    • Nature Materials
    Publisher Identifier (DOI)
    • https://doi.org/10.1038/s41563-021-01144-7
    Description
    • A full kinetic pathway of a non-classical nucleation-induced phase transformation through metastable states is elucidated at sub-angstrom resolution in a technologically important titanium alloy.
    • Two-phase titanium-based alloys are widely used in aerospace and biomedical applications, and they are obtained through phase transformations between a low-temperature hexagonal closed-packed alpha-phase and a high-temperature body-centred cubic beta-phase. Understanding how a new phase evolves from its parent phase is critical to controlling the transforming microstructures and thus material properties. Here, we report time-resolved experimental evidence, at sub-angstrom resolution, of a non-classically nucleated metastable phase that bridges the alpha-phase and the beta-phase, in a technologically important titanium-molybdenum alloy. We observed a nanosized and chemically ordered superstructure in the alpha-phase matrix; its composition, chemical order and crystal structure are all found to be different from both the parent and the product phases, but instigating a vanishingly low energy barrier for the transformation into the beta-phase. This latter phase transition can proceed instantly via vibrational switching when the molybdenum concentration in the superstructure exceeds a critical value. We expect that such a non-classical phase evolution mechanism is much more common than previously believed for solid-state transformations.
    Publication Date
    • 2021-11
    • 2022
  • Updated Acknowledgments Show Changes
    Acknowledgments
    • Author list: Xiaoqian Fu, Xu-Dong Wang, Beikai Zhao, Qinghua Zhang, Suyang Sun, Jiang-Jing Wang2 , Wei Zhang , Lin Gu  , Yangsheng Zhang, Wen-Zheng Zhang, Wen Wen , Ze Zhang, Long-qing Chen , Qian Yu  and En Ma
  • Deleted Creator Sandra Elder
  • Added Creator Xiaoqian Fu
  • Added Creator Xu-Dong Wang
  • Added Creator Beikai Zhao
  • Added Creator Qinghua Zhang
  • Added Creator Suyang Sun
  • Added Creator Jiang-Jing Wang
  • Added Creator Wei Zhang
  • Added Creator Lin Gu
  • Added Creator Yangsheng Zhang
  • Added Creator Wen-Zheng Zhang
  • Added Creator Wen Wen
  • Added Creator Ze Zhang
  • Added Creator Long-qing Chen
  • Added Creator Qian Yu
  • Added Creator En Ma
  • Updated