Universality of the plastic instability in strained amorphous solids

Area of Science:

• Materials Science
• Condensed Matter Physics
• Computational Materials Science

Background:

• Metallic glasses and Lennard-Jones glasses represent distinct classes of amorphous solids.
• Understanding plastic deformation mechanisms in glasses is crucial for materials design.
• Previous studies have focused on individual glass types, lacking comparative analysis.

Purpose of the Study:

• To investigate the universality of plastic instabilities in metallic glasses and Lennard-Jones glasses.
• To compare the microscopic differences and macroscopic similarities in their responses to external strain.
• To identify common underlying principles governing plastic flow in amorphous solids.

Main Methods:

• Athermal, quasistatic simulations were employed to model the response to external strain.
• Comparative analysis of stress-strain curves and energy landscapes was performed.
• Microscopic interactions (binary vs. multiple) were contrasted between the two glass types.

Main Results:

• A quantitative universality in fundamental plastic instabilities was observed in both metallic and Lennard-Jones glasses.
• The plastic instability in both systems was identified as a saddle-node bifurcation.
• Universal system-size exponents were found for stress and energy drops in the elastoplastic steady state.

Conclusions:

• Despite significant microscopic differences, metallic glasses and Lennard-Jones glasses share universal plastic instability characteristics.
• The saddle-node bifurcation serves as a common mechanism for plastic flow in diverse amorphous solids.
• These findings suggest a fundamental, universal description of plasticity in glasses.