Visualizing the strain evolution during the indentation of colloidal glasses.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Soft Matter Physics

Background:

• Understanding plastic deformation in amorphous solids like glasses is crucial.
• Colloidal glasses serve as a model system to study fundamental deformation mechanisms.

Purpose of the Study:

• To investigate the incipient plastic deformation in colloidal glasses using a nanoindentation analog.
• To visualize and analyze the strain field and structural changes during the onset of glass flow.

Main Methods:

• Employing a nanoindentation-like technique on a colloidal glass.
• Tracking individual particle motion in three dimensions to map strain fields.
• Analyzing both static and dynamic structural properties of the glass.

Main Results:

• Observed a power-law strain distribution at the onset of flow, signifying strongly correlated deformation and a critical state.
• Noted a transition to a Gaussian strain distribution at later stages, indicating uncorrelated plastic events.
• Found a weak correlation between glass structure (static/dynamic measures) and the emerging strain distribution.

Conclusions:

• The onset of plasticity in colloidal glasses is primarily governed by strong, power-law strain correlations.
• Heterogeneous glass structure weakly influences the initial plastic deformation.
• Plasticity in glasses may be understood as a critical phenomenon.