Mechanical failure in amorphous solids: Scale-free spinodal criticality

Area of Science:

• Materials Science
• Physics
• Geology

Background:

• Mechanical failure in amorphous media is a scale-free phenomenon, suggesting criticality.
• Previous explanations like Self-Organized Criticality have not fully elucidated its physical origin or universal nature.

Purpose of the Study:

• To propose and demonstrate that the critical behavior in amorphous media failure is a spinodal point of a thermodynamic phase transition.
• To introduce a universal order parameter for distinguishing disordered amorphous systems.
• To extend the understanding from athermal to thermal systems.

Main Methods:

• Introduction of a novel order parameter suitable for amorphous systems.
• Analysis of correlation functions to identify a divergent correlation length.
• Theoretical extension to include thermal effects on the spinodal phenomenon.

Main Results:

• The mechanical yield criticality in amorphous solids is identified as a spinodal point.
• A divergent correlation length, linked to system-spanning instabilities (shear bands), is observed at the spinodal point.
• The proposed theory and order parameter demonstrate universality across different amorphous solids.

Conclusions:

• The spinodal point provides a physical explanation for the criticality and universality of mechanical failure in amorphous materials.
• The identified order parameter and correlation functions are applicable to various amorphous solids.
• Thermal fluctuations can disrupt the spinodal phenomenon at high temperatures.