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Kink nucleation in the two-dimensional Frenkel-Kontorova model
Yu N Gornostyrev1, M I Katsnelson, A V Kravtsov
1Institute of Metal Physics, Ekaterinburg 620219, Russia.
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|September 21, 2002
Summary
Computer simulations reveal that low-temperature kink nucleation on dislocations occurs via phonon mode instability. This mechanism transitions to standard thermofluctuation nucleation with increasing temperature, impacting yield stress.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Computational Physics
Background:
- Dislocation mobility is crucial for plastic deformation in materials.
- Thermofluctuation nucleation of kinks is a key mechanism controlling dislocation motion.
- Understanding kink nucleation dynamics at varying temperatures is essential for predicting material behavior.
Purpose of the Study:
- To investigate the mechanism of thermofluctuation kink nucleation on dislocations using computer simulations.
- To explore the role of phonon modes in kink nucleation at low temperatures.
- To analyze the temperature dependence of kink nucleation and its effect on yield stress.
Main Methods:
- Utilized a two-dimensional Frenkel-Kontorova model for computer simulations.
- Analyzed the dynamics of kink nucleation and movement on dislocations.
- Investigated the influence of temperature and applied stress on the nucleation process.
Main Results:
- Demonstrated that at low temperatures and stresses, kinks nucleate via instability of localized phonon modes near dislocations.
- Observed a transition in the nucleation mechanism from phonon instability to standard thermofluctuation nucleation as temperature increases.
- Identified that this transition mechanism can manifest in specific features of the yield stress temperature dependence.
Conclusions:
- The study reveals a novel low-temperature mechanism for kink nucleation on dislocations driven by phonon instabilities.
- The findings provide insights into the complex interplay between temperature, stress, and dislocation dynamics.
- The observed transition mechanism offers a potential explanation for anomalies in the temperature dependence of material yield strength.
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