A structural disorder function linking local symmetry breaking to plastic indicators and strength in amorphous solids

Area of Science:

• Materials Science
• Condensed Matter Physics
• Computational Materials Science

Background:

• Understanding structure-property relationships in amorphous solids is challenging due to the lack of long-range order.
• Existing structural descriptors often fail to capture universal characteristics of disordered systems.

Purpose of the Study:

• To introduce a novel, physically interpretable metric for atomic-scale disorder in amorphous materials.
• To establish a quantitative link between structural disorder and macroscopic mechanical properties.

Main Methods:

• Development of the structural disorder function, Sd(r), based on local symmetry breaking.
• Application of molecular dynamics simulations across various amorphous alloys and glasses.
• Validation using colloidal-glass experiments.

Main Results:

• Sd(r) correlates strongly (R > 0.68) with key mechanical properties like vibrational mean-square displacement and atomic stiffness.
• Higher Sd(r) values identify liquid-like regions, distinguishing mechanical heterogeneity.
• A universal negative linear relationship was found between average Sd(r) and shear strength.

Conclusions:

• Sd(r) serves as a simple, dimensionless, and broadly applicable descriptor for disordered materials.
• This metric unifies atomic configuration, processing history, and mechanical response.
• Provides a physics-based framework for the rational design of amorphous solids.