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Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
Published on: June 7, 2018
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Fractal atomic-level percolation in metallic glasses
David Z Chen1, Crystal Y Shi2, Qi An3
1Division of Engineering and Applied Sciences, California Institute of Technology, Pasadena, CA 91125, USA. dzchen@caltech.edu.
Science (New York, N.Y.)
|September 19, 2015
Summary
Metallic glasses exhibit exotic properties, with fractal structures explained by percolation clusters. Atoms percolate in the liquid phase, becoming rigid at the glass transition temperature, revealing a new organization mechanism.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Computational Materials Science
Background:
- Metallic glasses possess unique properties attributed to their atomic-level structures.
- The underlying physical mechanism for the organization of these non-crystalline structures, particularly fractal aspects, remains poorly understood.
Purpose of the Study:
- To elucidate the structural organization mechanism in metallic glasses.
- To identify the relationship between short-range fractal and long-range homogeneous structures.
- To validate the percolation cluster model for metallic glass structures.
Main Methods:
- In situ X-ray diffraction
- X-ray tomography
- Molecular dynamics simulations
Main Results:
- Demonstrated a structural crossover from fractal to homogeneous organization with increasing range.
- Identified the percolation cluster as a model explaining structural details across various metallic glass compositions.
- Correlated atomic percolation in the liquid phase with structural rigidity at the glass transition temperature.
Conclusions:
- The percolation cluster model provides a physical mechanism for the atomic organization in metallic glasses.
- Atomic percolation in the liquid state is a key factor leading to the rigid structure of metallic glasses upon cooling.
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