Yield Precursor Dislocation Avalanches in Small Crystals: The Irreversibility Transition.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Statistical Mechanics

Background:

• Crystalline metals exhibit history dependence and scale-invariant avalanche signatures during plastic deformation, similar to other nonequilibrium systems.
• Non-equilibrium systems, like colloidal suspensions, show transitions analogous to work hardening and yield stress, often requiring training via cyclic loading for elastic behavior.

Purpose of the Study:

• To investigate whether small crystalline metals share key characteristics with other nonequilibrium systems undergoing transitions.
• To analyze yielding and hysteresis in single-crystalline copper (Cu) pillars under cyclic loading.

Main Methods:

• Uniaxial compression experiments were performed on single-crystalline Cu nano- and micropillars.
• Cyclic loading protocols were applied to observe the evolution of deformation behavior.
• Analysis focused on the decay of yielding and hysteresis, and the scaling of yield precursor avalanches.

Main Results:

• Yielding and hysteresis in Cu pillars decay under repeated cyclic loading.
• The amplitude and decay time of yield precursor avalanches diverge as peak stress approaches the failure stress.
• Power-law scaling was observed, consistent with reversible-to-irreversible transitions (RITs) in other nonequilibrium systems.

Conclusions:

• Deformation in small crystalline metals shares fundamental characteristics with other complex nonequilibrium systems.
• Universal scaling laws govern plastic deformation and transitions in diverse physical systems.
• The findings provide insights into the physics of plasticity and material failure.