Abstract
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 language | English (US) |
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Pages (from-to) | 290-296 |
Number of pages | 7 |
Journal | Nature Materials |
Volume | 21 |
Issue number | 3 |
DOIs | |
State | Published - Mar 2022 |
All Science Journal Classification (ASJC) codes
- General Chemistry
- General Materials Science
- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering