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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
Amorphous precursors of crystallization during spinodal decomposition
Leopoldo R Gómez1, Daniel A Vega
1Department of Physics and Instituto de Física del Sur, IFISUR (UNS-CONICET), Além 1253, (8000) Bahía Blanca, Argentina. gomez@lorentz.leidenuniv.nl
Summary
This study reveals that liquid-solid spinodal decomposition (SD) initially forms icosahedral precursors. These precursors then facilitate heterogeneous nucleation of body-centered cubic crystalline structures.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Physical Chemistry
Background:
- Liquid-solid phase transitions are fundamental in materials science.
- Spinodal decomposition (SD) is a critical mechanism for phase separation.
- Understanding crystallization dynamics is key to controlling material properties.
Purpose of the Study:
- To investigate the crystallization dynamics during liquid-solid spinodal decomposition (SD).
- To elucidate the role of precursors in heterogeneous nucleation.
- To analyze the influence of quench depth on crystalline phase formation.
Main Methods:
- Utilizing a general Landau free energy functional.
- Simulating the early stages of spinodal decomposition.
- Analyzing the structural evolution of amorphous and crystalline phases.
Main Results:
- Early-stage SD promotes small, icosahedral-ordered precursors.
- These precursors aggregate into dense clusters of tetrahedra.
- Heterogeneous nucleation of body-centered cubic crystals occurs on these clusters.
- Crystalline volume fraction depends significantly on quench depth.
- Deep quenches yield amorphous structures in dense polytetrahedral aggregates.
Conclusions:
- The study provides insights into the mechanism of crystallization during SD.
- Identifies icosahedral precursors as key intermediates.
- Highlights the control over crystalline structure via quench depth.
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