Investigating the cross-slip rate in face-centered cubic metals using an atomistic-based cross-slip model in dislocation dynamics simulations

Longsworth, M.; Fivel, M.

doi:10.1016/j.jmps.2021.104449

Cited by 3 publications

(2 citation statements)

References 35 publications

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“…We now seek a close-form expression for

as a function of stress, which will not only reveal more insight into the physical nature of the activation entropy but also provide a needed tool for predicting the cross-slip rate in mesoscale models such as discrete dislocation dynamics ( 18 , 43 ). We begin by defining

as the stress of the crystal at zero temperature when subjected to the strain

, i.e.,

.…”

Section: Discussionmentioning

confidence: 99%

Stress-dependent activation entropy in thermally activated cross-slip of dislocations

Wang

Cai

2023

Proc. Natl. Acad. Sci. U.S.A.

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Cross-slip of screw dislocations in crystalline solids is a stress-driven thermally activated process essential to many phenomena during plastic deformation, including dislocation pattern formation, strain hardening, and dynamic recovery. Molecular dynamics (MD) simulation has played an important role in determining the microscopic mechanisms of cross-slip. However, due to its limited timescale, MD can only predict cross-slip rates in high-stress or high-temperature conditions. The transition state theory can predict the cross-slip rate over a broad range of stress and temperature conditions, but its predictions have been found to be several orders of magnitude too low in comparison to MD results. This discrepancy can be expressed as an anomalously large activation entropy whose physical origin remains unclear. Here, we resolve this discrepancy by showing that the large activation entropy results from anharmonic effects, including thermal softening, thermal expansion, and soft vibrational modes of the dislocation. We expect these anharmonic effects to be significant in a wide range of stress-driven thermally activated processes in solids.

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“…We now seek a close-form expression for

as the stress of the crystal at zero temperature when subjected to the strain

, i.e.,

.…”

Section: Discussionmentioning

confidence: 99%

Stress-dependent activation entropy in thermally activated cross-slip of dislocations

Wang

Cai

2023

Proc. Natl. Acad. Sci. U.S.A.

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show abstract

“…It has been found that activation of such mechanisms does not conceptually modify the results. Simulations with more realistic description of cross-slipping using the atomistic-based model developed by Longsworth and Fivel [64] will be made in a future work.…”

Section: Methodology and Modeling Assumptionsmentioning

confidence: 99%