Bulk metallic glasses deform via slip avalanches.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Solid Mechanics

Background:

• Metallic glasses exhibit complex deformation behaviors under stress.
• Understanding the fundamental mechanisms of plastic deformation in amorphous materials is crucial.
• Previous models have struggled to fully capture the statistics and dynamics of deformation events.

Purpose of the Study:

• To characterize the nature, statistics, and dynamics of slip events in metallic glasses during slow deformation.
• To test a mean field model based on coupled shear transformation zones (STZs).
• To determine if the observed phenomena align with self-organized criticality.

Main Methods:

• Utilizing high temporal resolution experimental measurements.
• Applying a simple mean field model to simulate atomic rearrangements in coupled STZs.
• Extracting exponents and scaling functions describing slip event characteristics.

Main Results:

• Successfully extracted exponents and scaling functions for slip events.
• Observed distinct statistics and dynamics for small and large slip events, differing from predictions of self-organized criticality.
• Demonstrated strong agreement between experimental data and the mean field STZ model across multiple measures.

Conclusions:

• Slip avalanches of STZs are identified as the elementary mechanism for inhomogeneous deformation in metallic glasses.
• The findings exclude self-organized criticality as the governing principle for these deformation events.
• The study validates a mean field model for understanding plastic flow in metallic glasses.