Crackling noise in crystal plasticity: power-law avalanche statistics in metal deformation
When metals are deformed, dislocations (line defects) move in discrete avalanches rather than continuously. Each avalanche emits a burst of acoustic emission (AE) — crackling noise.
This is a signature of self-organized criticality (SOC): the system tunes itself to a critical state without fine-tuning. Each avalanche triggers neighbors via stress redistribution.
The AE energy E scales with avalanche size S: E ~ S² (linear elasticity). Experiments (Dimiduk 2006, Brinckmann 2008) confirm power laws in single-crystal micropillars.