Kinetics of dislocation cross-slip: A molecular dynamics study

Oren, Eyal; Yahel, Eyal; Makov, Guy

doi:10.1016/j.commatsci.2017.06.039

Cited by 24 publications

(31 citation statements)

References 42 publications

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“…However, the three stresses have similar influence on the energy barrier when they are below 100 MPa. The effective attempt frequency ν ef f , obtained from MD simulations, was in the range from 5×10 11 to 1×10 13 s −1 , which is in agreement with previous studies [29,20]. The activation entropy, ∆S, was estimated from ν ef f and eqs.…”

Section: Molecular Dynamics Results 421 Uncoupled Stressessupporting

confidence: 88%

“…However, our calculations show the formation of a perfect screw dislocation segment between the nodes. This effect was reported recently by Oren et al [20]. Once the saddle point is reached, both constrictions expand in opposite directions, enforcing the re-dissociation of the partials on the cross-slip plane.…”

Section: Nudged Elastic Band Simulations Resultssupporting

confidence: 78%

“…Atomistic path sampling methods along with the replica trimming algorithm were employed to investigate the influence stress tensor on the cross-slip process. In addition, molecular dynamics simulations have been used to assess the time necessary for a dislocation segment to cross-slip as function of the temperature and of the applied stress and they were successfully used to determine the cross-slip activation free energy in Cu [29] and, in combination with path sampling, to determine the influence of stress on the cross-slip rate without previous assumptions [20]. Finally, Xu et al [30] compared molecular dynamics simulations with the multiscale concurrent atomistic-continuum (CAC) methodology, which provided comparable results with lower computational cost.…”

Section: Introductionmentioning

confidence: 99%

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Influence of the stress state on the cross-slip free energy barrier in Al: An atomistic investigation

et al. 2020

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The influence of the stress state on the cross-slip rate in Al was analyzed by means of molecular dynamics simulations and transition state theory. The activation energy barrier in the absence of thermal energy was determined through the nudged elastic band method while the cross-slip rates were determined using molecular dynamics simulations for different magnitudes of the Schmid stress on the cross-slip plane, and of the Escaig stresses on the cross-slip and glide planes. The enthalpy barrier and the effective attempt frequency were determined from the average rates of cross-slip obtained from the molecular dynamics simulations. It was found that the different stress states influence the cross-slip rate assuming harmonic transition state theory. Moreover, the theoretical contributions to the enthalpy barrier (configurational and due to the interaction of the applied stress with the local stress field created by the defect) were identified from the atomistic simulations while the entropic contribution to the activation energy could be estimated by the Meyer-Neldel rule. Based on these results, an analytical expression of the activation enthalpy for cross-slip in Al as a function of the different combinations of Schmid and Escaig stress states was developed and validated. This expression can be easily used in dislocation dynamics simulations to evaluate the probability of cross-slip of screw dislocation segments.

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Section: Molecular Dynamics Results 421 Uncoupled Stressessupporting

confidence: 88%

Section: Nudged Elastic Band Simulations Resultssupporting

confidence: 78%

Section: Introductionmentioning

confidence: 99%

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Influence of the stress state on the cross-slip free energy barrier in Al: An atomistic investigation

et al. 2020

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“…Many previous studies focused on the mechanism and energy of cross-slip in pure metals, see for instance the review [ 6] and Refs. [ [7][8][9][10]. The most prominent mechanism is the Friedel-Escaig [11,12] mechanism.…”

Section: Introductionmentioning

confidence: 99%

“…Cross-slip is a thermally activated mechanism and it has been shown [9,14] that the rate of cross-slip can be described by an Arrhenius expression,…”

Section: Introductionmentioning

confidence: 99%

Cross-slip of long dislocations in FCC solid solutions

Nöhring

Curtin

2018

Acta Materialia

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Cross-slip of screw dislocations is a dislocation process involved in dislocation structuring, work hardening, and fatigue. Cross-slip nucleation in FCC solid solution alloys has recently been shown to be strongly influenced by local fluctuations in spatial arrangement of solutes, leading to a statistical distribution of cross-slip nucleation barriers. For cross-slip to be effective macroscopically, however, small cross-slip nuclei (~40b) must expand across the entire length of typical dislocation segments (10 2-10 3 b). Here, a model is developed to compute the relevant activation energy distribution for cross-slip in a random FCC alloy over arbitrary lengths and under non-zero Escaig and Schmid stresses. The model considers cross-slip as a random walk of successive flips of adjacent1b segments, with each flip having an energy consisting of a deterministic contribution due to constriction formation and stress effects, plus a stochastic contribution. The corresponding distribution is computed analytically from solute-dislocation and solute-solute binding energies. At zero stress, the probability of high activation energies increases with dislocation length. However, at stresses of just a few MPa, these barriers are eliminated and lower barriers are dominant. For increasing segment length, the effective energy barrier decreases according to a weak-link scaling relationship and good analytic predictions can be made using only known material properties. Overall, these results show that the effective cross-slip barrier in a random alloy is significantly lower than estimates based on average elastic and stacking fault properties of the alloy.

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