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08:55
Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
Published on: June 7, 2018
Long-range topological order in metallic glass
Qiaoshi Zeng1, Hongwei Sheng, Yang Ding
1International Center for New-Structured Materials, Zhejiang University, Hangzhou 310027, People's Republic of China.
Science (New York, N.Y.)
|June 18, 2011
Summary
Metallic glass exhibits hidden long-range order. Under high pressure, Ce(75)Al(25) metallic glass transforms into a single crystal, revealing its underlying topological structure.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Crystallography
Background:
- Crystals possess long-range periodic atomic order, unlike amorphous materials such as metallic glasses.
- The Ce(75)Al(25) metallic glass was previously considered structurally amorphous and isotropic.
Purpose of the Study:
- To investigate the hidden structural order within the Ce(75)Al(25) metallic glass.
- To understand the mechanism of pressure-induced crystallization in this metallic glass.
Main Methods:
- High-pressure experiments utilizing hydrostatic pressures up to 25 gigapascals.
- Synchrotron X-ray diffraction techniques for structural analysis.
- Molecular dynamics simulations to model atomic behavior.
Main Results:
- The Ce(75)Al(25) metallic glass, despite appearing amorphous, possesses a long-range topological order.
- Under high pressure, the metallic glass transforms into a single face-centered cubic (fcc) crystal with a uniform orientation.
- Atom size mismatch between Ce and Al hinders crystallization but a topological order persists.
Conclusions:
- A long-range fcc topological order exists in Ce(75)Al(25) metallic glass, masked by atomic mismatch.
- Pressure-induced electronic transition in Cerium removes the atomic mismatch, enabling the topological order to manifest as a single crystal.
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