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Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
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Crossover from Localized to Cascade Relaxations in Metallic Glasses
Yue Fan1, Takuya Iwashita2, Takeshi Egami1,2,3
1Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
Physical Review Letters
|August 8, 2015
Summary
Thermally activated deformation in metallic glasses reveals two distinct modes. Cascade deformation, more common in rapidly cooled systems, stems from a denser potential energy landscape.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Computational Materials Science
Background:
- Metallic glasses exhibit unique mechanical properties due to their amorphous structure.
- Understanding deformation mechanisms is crucial for designing advanced materials.
Purpose of the Study:
- To investigate thermally activated deformation in metallic glasses.
- To differentiate deformation modes based on cooling history.
- To elucidate the atomic origins of observed deformation behaviors.
Main Methods:
- Simulating atomic displacements and stress changes.
- Analyzing the potential energy landscape.
- Comparing two metallic glass systems with varying cooling rates (fast vs. slow quench).
Main Results:
- Two deformation modes were identified: localized and cascade.
- Localized deformation ( < 30 atoms) was independent of cooling history.
- Cascade deformation occurred more frequently in fast-quenched systems.
- Cascade process origin linked to higher density of local minima in fast-quenched systems.
Conclusions:
- Cooling history significantly influences the prevalence of cascade deformation in metallic glasses.
- The potential energy landscape's topology dictates deformation mode frequency.
- Atomic-level insights into metallic glass plasticity are provided.
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