The fractal correlation between relaxation dynamics and atomic-level structures observed in metallic glasses by...

Area of Science:

• Condensed Matter Physics
• Materials Science
• Computational Chemistry

Background:

• Amorphous materials exhibit complex relaxation dynamics.
• Understanding the atomic-scale mechanisms is crucial for material design.
• Previous models often lack detailed microscopic insights.

Purpose of the Study:

• To elucidate the microscopic mechanism governing relaxation dynamics in amorphous materials.
• To identify and characterize the key atomic entities involved in relaxation.
• To explore the relationship between atomic motion, free volume, and structural organization.

Main Methods:

• Atomistic simulations were employed to model material behavior.
• Unsupervised machine learning, specifically hierarchical clustering, was used for analysis.
• Correlation analysis was performed to investigate relationships between variables.

Main Results:

• Microscopic relaxation is driven by 'activating atoms' with significant displacement.
• Activating atoms exhibit cooperative, avalanche-like behavior, forming 'activating units'.
• Large free volumes promote the formation of activating atoms, and fractal correlations exist in unit size and number.

Conclusions:

• The study reveals a cooperative, avalanche-like atomic mechanism for amorphous material relaxation.
• Free volume plays a critical role in facilitating atomic mobility and relaxation.
• A fractal structure emerges in the organization of activating units at the percolation threshold.