Training-induced criticality in martensites

Area of Science:

• Materials Science
• Condensed Matter Physics
• Dynamical Systems

Background:

• Martensitic transformations are crucial in materials science, exhibiting complex behaviors during cyclic loading.
• The phenomenon of 'training' in martensites leads to self-organization and criticality, suggesting underlying fundamental mechanisms.
• Understanding these mechanisms is key to controlling material properties and performance.

Purpose of the Study:

• To propose a theoretical explanation for the self-organization towards criticality in martensites during the training process.
• To elucidate the interplay between reversible phase transformation and lattice defect activity in driving scale-free behavior.
• To model the observed phenomena using a dynamical system approach.

Main Methods:

• Development of a continuous dynamical system model on a rugged energy landscape.
• Reduction of the dynamical system to a sandpile automaton in the quasistatic limit.
• Simulation and analysis of the model to reproduce experimental observations.

Main Results:

• The model successfully explains the origin of scale-free behavior in trained martensites.
• It reproduces key experimental observations, including power-law statistics and hysteresis shakedown.
• The model also accounts for asymmetric signal shapes and correlated disorder in martensitic systems.

Conclusions:

• The proposed dynamical system model provides a unified explanation for criticality in trained martensites.
• The interplay between phase transformation and defects is identified as the core mechanism.
• This work offers insights into the fundamental physics governing martensitic training and self-organization.