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

Xiaoqian Fu, Xu Dong Wang, Beikai Zhao, Qinghua Zhang, Suyang Sun, Jiang Jing Wang, Wei Zhang, Lin Gu, Yangsheng Zhang, Wen Zheng Zhang, Wen Wen, Ze Zhang, Long qing Chen, Qian Yu, En Ma

Research output: Contribution to journalArticlepeer-review

43 Scopus citations


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 α-phase and a high-temperature body-centred cubic β-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-ångström resolution, of a non-classically nucleated metastable phase that bridges the α-phase and the β-phase, in a technologically important titanium–molybdenum alloy. We observed a nanosized and chemically ordered superstructure in the α-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 β-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.

Original languageEnglish (US)
Pages (from-to)290-296
Number of pages7
JournalNature Materials
Issue number3
StatePublished - Mar 2022

All Science Journal Classification (ASJC) codes

  • General Chemistry
  • General Materials Science
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering


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