Campus Units

Aerospace Engineering, Mechanical Engineering, Ames Laboratory

Document Type

Article

Publication Version

Accepted Manuscript

Publication Date

1-6-2021

Journal or Book Title

Acta Materialia

First Page

116623

DOI

10.1016/j.actamat.2021.116623

Abstract

The stationary motion of shuffle screw and 60∘ dislocations in silicon when the applied shear, τap, is much below the static Peierls stress,τpmax, is proved and quantified through a series of molecular dynamics (MD) simulations at 1 K and 300 K, and also by solving the continuum-level equation of motion, which uses the atomistic information as inputs. The concept of a dynamic Peierls stress, τpd, below which a stationary dislocation motion can never be possible, is built upon a firm atomistic foundation. In MD simulations at 1 K, the dynamic Peierls stress is found to be 0.33GPa for a shuffle screw dislocation and 0.21GPa for a shuffle 60∘ dislocation, versus τpmax of 1.71GPa and 1.46GPa, respectively. The critical initial velocity v0c(τap) above which a dislocation can maintain a stationary motion at τpd<τap<τpmax is found. The velocity dependence of the dissipation stress associated with the dislocation motion is then characterized and informed into the equation of motion of dislocation at the continuum level. A stationary dislocation motion below τpmax is attributed to: (i) the periodic lattice resistance smaller than τpmax almost everywhere; and (ii) the change of a dislocation’s kinetic energy, which acts in a way equivalent to reducing τpmax. The results obtained here open up the possibilities of a dynamic intensification of plastic flow and defects accumulations, and consequently, the strain-induced phase transformations. Similar approaches can be applicable to partial dislocations, twin and phase interfaces.

Comments

This is a manuscript of an article published as Chen, Hao, Valery I. Levitas, Liming Xiong, and Xiancheng Zhang. "Stationary Dislocation Motion at Stresses Significantly below the Peierls Stress: Example of Shuffle Screw and 60∘ Dislocations in Silicon." Acta Materialia (2021): 116623. DOI: 10.1016/j.actamat.2021.116623. Posted with permission.

Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

Copyright Owner

Acta Materialia Inc.

Language

en

File Format

application/pdf

Available for download on Thursday, January 06, 2022

Published Version

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