Development of new interatomic potentials appropriate for crystalline and liquid iron

Mendelev, Mikhail I.; Han, Seungwu; Srolovitz, David J.; Ackland, Graeme J.; Sun, Dongmei; Asta, Mark

doi:10.1080/14786430310001613264

Cited by 1,196 publications

(825 citation statements)

References 27 publications

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“…Also, implementation of a slightly different potential energy function [18] in our KMC technique did not have any significant change in barrier heights, rate values or set of possible transitions for the 110 DB.…”

Section: Interstitialsmentioning

confidence: 99%

Influence of the prefactor to defect motion inα-Iron during long time scale simulations

Lazauskas¹,

Kenny²,

Smith³

2014

J. Phys.: Condens. Matter

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We present a study of the influence of the prefactor in the Arrhenius equation for the long time scale motion of defects in α-Fe. It is shown that calculated prefactors vary widely between different defect types and it is thus important to determine these accurately when implementing on-the-fly kinetic Monte Carlo (otf-KMC) simulations. The results were verified by reproducing many events using Molecular Dynamics (MD) and Temperature-Accelerated Dynamics (TAD). The calculated prefactor was shown to increase the relative interstitial-vacancy diffusion rates by an order of magnitude compared to the assumption of a constant prefactor value and the ordering of the rate table for the interstitial defect migration mechanisms was also changed. In addition, low prefactor values were observed for the 4 interstitial dumbbells configuration with low barrier transitions.

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Section: Interstitialsmentioning

confidence: 99%

Influence of the prefactor to defect motion inα-Iron during long time scale simulations

Lazauskas¹,

Kenny²,

Smith³

2014

J. Phys.: Condens. Matter

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“…The complex core structure is heavily influenced by the choice of interatomic potential used in classical atomistic simulations. The vast majority of existing potentials predict a screw dislocation has multiple core structures 36,37 , leading many authors to suggest that a screw dislocation may pass through a metastable core structure during the kink nucleation process 35 . Under an applied stress this can produce a new kink formation pathway leading to a discontinuity in the flow stress 1,6,16 .…”

Section: Stochastic Motion Of Isolated Kinks On Screw Dislocation mentioning

confidence: 99%

Theory and simulation of the diffusion of kinks on dislocations in bcc metals

et al. 2013

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Isolated kinks on thermally fluctuating (1/2) 111 screw, 100 edge and (1/2) 111 edge dislocations in bcc iron are simulated under zero stress conditions using molecular dynamics (MD). Kinks are seen to perform stochastic motion in a potential landscape that depends on the dislocation character and geometry, and their motion provides fresh insight into the coupling of dislocations to a heat bath. The kink formation energy, migration barrier and friction parameter are deduced from the simulations. A discrete Frenkel-Kontorova-Langevin (FKL) model is able to reproduce the coarse grained data from MD at ∼10 −7 of the computational cost, without assuming an a priori temperature dependence beyond the fluctuation-dissipation theorem. Analytic results reveal that discreteness effects play an essential rôle in thermally activated dislocation glide, revealing the existence of a crucial intermediate length scale between molecular and dislocation dynamics. The model is used to investigate dislocation motion under the vanishingly small stress levels found in the evolution of dislocation microstructures in irradiated materials.Dislocation motion is limited by two general processes, the formation and migration of kinks and pinning by impurities and other defects 1 . In this paper we investigate the motion of kink-limited screw and edge dislocations in bcc Fe, where the kink formation energy is much larger than the thermal energy. To obtain dislocation motion on the time-scales accessible to molecular dynamics (MD) simulations some researchers have resorted to inducing kink formation by applying stresses some six orders of magnitude greater than those pertaining experimentally 2,3 .But dislocation core structures and Peierls barriers are known to be highly stress-dependent 4 , making it difficult to relate simulation to the vanishingly low stress conditions found in thermally activated evolution of dislocation microstructures.To avoid the problem of nucleating kinks in MD simulations we use periodic boundary conditions which enforce the existence of an isolated kink on each dislocation line in the supercell. This allows us to study the detailed dynamics of kink migration in isolation, a crucial and previously unexplored aspect of kink-limited dislocation motion, as seperate from the kink nucleation process. Under no applied stress, kinks are seen to undergo stochastic motion in a potential landscape that varies with the dislocation character and Burgers vector. A coarse graining procedure is introduced, that facilitates statistical analysis yielding many properties of the kink motion, and which provides physical insight into the coupling of dislocations to the heat bath. In particular, the friction parameter for a dislocation is found to be temperature-independent, contradicting decades of theoretical work since Liebfried 5 . But this temperature-independence is seen in many other investigations of dislocations 2,3,6 with a large lattice resistance and in the stochastic motion of point defects 8,9 , although to the best of our ...

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“…We take V F eF e , φ F eF e and F F e from our previous paper [13]. The φs are taken by scaling the pure iron values.…”

Section: B Fittingmentioning

confidence: 99%

“…Recent ab initio work [12,13] shows that at high densities the resistance to compression arises from a many-body effect (electronic kinetic energy) rather than a pairwise repulsion. Fitting compression data using the short range part of V (r ij ) typically leads to an overestimate of interstitial formation energies and volumes [14].…”

Section: Introductionmentioning

confidence: 99%

“…We have shown that including different things in the fit leads to very different potentials: to describe point defect interactions, one must fit point defect properties. and so we use an iron potential optimised for point defects as the basis of the present work [13]. This incorporates the kinetic energy effect by writing F (x) = − √ x + a 2 x 2 + a 4 x 4 , with increasing x taking us smoothly between hopping and free-electron dominated regimes.…”

Section: Introductionmentioning

confidence: 99%

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Development of an interatomic potential for phosphorus impurities in -iron

Ackland

Mendelev

Srolovitz

et al. 2004

J. Phys.: Condens. Matter

559

382

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We present the derivation of an interatomic potential for the iron phosphorus system based primarily on ab initio data. Transferrability in this system is extremely problematic, and the potential is intended specifically to address the problem of radiation damage and point defects in iron containing low concentrations of phosphorus atoms. Some preliminary molecular dynamics calculations show that P strongly affects point defect migration.

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Development of new interatomic potentials appropriate for crystalline and liquid iron

Cited by 1,196 publications

References 27 publications

Influence of the prefactor to defect motion inα-Iron during long time scale simulations

Influence of the prefactor to defect motion inα-Iron during long time scale simulations

Theory and simulation of the diffusion of kinks on dislocations in bcc metals

Development of an interatomic potential for phosphorus impurities in -iron

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