Kink nucleation in two-dimensional Frenkel-Kontorova model

TL;DR

This study uses computer simulations within a 2D Frenkel-Kontorova model to explore how thermofluctuation-induced kinks nucleate and evolve on dislocations, revealing temperature-dependent transition mechanisms affecting material yield stress.

Contribution

It demonstrates the nucleation mechanism of kinks via phonon mode instability and its transition to thermofluctuation nucleation in a 2D model, linking microscopic dynamics to macroscopic yield behavior.

Findings

Kinks can nucleate due to phonon mode instability at low temperatures.

Transition from phonon instability to thermofluctuation nucleation occurs with increasing temperature.

Yield stress dependence on temperature shows signatures of this transition.

Abstract

A computer simulation of thermofluctuation nucleation of kinks on dislocations and their dynamics is carried out in the framework of two-dimensional (2D) Frenkel-Kontorova model. It is shown that at relatively low temperatures and applied stresses the kinks can appear as a result of developing instability of phonon modes localized in the vicinity of the dislocation. The transition from this mechanism to the ordinary thermofluctuation kink nucleation with temperature increase can reveal itself in the peculiarities of yield stress temperature dependence.