Dislocation interaction with C in α-Fe: A comparison between atomic simulations and elasticity theory

Clouet, Emmanuel; Garruchet, Sébastien; Nguyen, Hoang; Perez, Michel; Becquart, Charlotte

doi:10.1016/j.actamat.2008.03.024

Cited by 194 publications

(146 citation statements)

References 41 publications

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“…Such estimates are generally not sufficiently accurate for real predictions and should be replaced by the more general definition using the misfit volumes of the solutes in the actual alloy of interest. These misfit volumes are well-defined quantities from both thermodynamics and mechanics perspectives, do not rely on any Vegard's law as-sumption, do not require the elements to crystallize in the same structure, and are simple enough to be computable using ab initio calculations [13,17,74].…”

Section: Elastic Interaction Modelmentioning

confidence: 99%

“…This interaction energy U el (x i , y j ) = −p(x i , y j )∆V , also referred to as the first order "size" interaction [12], is equal to the work done on the dislocation pressure field by the expansion or contraction of the material upon addition of the misfitting solute atom. This mechanical interaction energy can be generalized to include the interaction energy between deviatoric misfit strains and the deviatoric dislocation stress field (the first order "shape" interaction), which is typically important for interstitial solutes [13,14,15]. For simplicity here, we focus on misfit volumetric strains that are appropriate for substitutional solutes in cubic matrices [16,17].…”

Section: Introductionmentioning

confidence: 99%

“…For simplicity here, we focus on misfit volumetric strains that are appropriate for substitutional solutes in cubic matrices [16,17]. The elastic interactions are long-ranged, since the dislocation stress field decays only as 1/r with distance r from the center of the dislocation, and give a quantitative description of the solute/dislocation interaction away from immediate dislocation core region [13,14,15,16,17,18].…”

Section: Introductionmentioning

confidence: 99%

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Solute strengthening in random alloys

et al. 2017

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Random solid solution alloys are a broad class of materials that are used across the entire spectrum of engineering metals, whether as stand-alone materials (e.g. Al-5xxx alloys) or as the matrix in precipitatestrengthening materials (e.g. Ni-based superalloys). As a result, the mechanisms of, and prediction of, strengthening in solid solutions has a long history. Many concepts have been developed and important trends identified but predictive capability has remained elusive. In recent years, a new theory has been developed that builds on one historical model, the Labusch model, in important ways that lead to a well-defined model valid for random solutions with arbitrary numbers of components and compositions. The new theory uses first-principles-computed solute/dislocation interaction energies as input, from which specific predictions emerge for the yield strength and activation volume as a function of alloy composition, temperature, and strain-rate. Being a general model for materials that otherwise have a low Peierls stress, it has broad application and has been successfully applied to Al-X alloys, Mg-Al, twinning in Mg alloys, and recently fcc High-Entropy Alloys. Here, the new theory is presented in a general and systematic manner. Approximations and limiting cases that reduce the complexity and facilitate understanding are introduced, and help relate the new model to various physical features present among the historical array of models. The quantitative predictions of the model in the various materials above is then demonstrated.

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Section: Elastic Interaction Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Solute strengthening in random alloys

et al. 2017

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“…Other techniques to determine the dislocation position are to calculate the deviation of the atomic displacements from the anisotropic elastic field 20 , or the bonding disregistry across the slip plane 21 . However, we found that the procedure employed here gave better localization at finite temperature and is applicable to many different dislocation geometries.…”

Section: Molecular Dynamics Simulation Of Thermally Fluctuating DImentioning

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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“…as-quenched martensite) leads to a rapid stress-induced ordering of the solute carbon atoms, where these migrate towards dislocation stress fields [12]. Atomistic and first-principle calculations typically report the diffusion path of carbon atoms to be from OIS to vacant sites, via TIS [13][14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic aspects of carbon redistribution during ageing and tempering of Fe–Ni–C alloys

Kim

Sietsma

Santofimia

2016

Philosophical Magazine

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Carbon redistribution is known to occur during martensite ageing. The two associated processes most discussed in the literature are spinodal decomposition and carbon segregation to defects. In order to elucidate the topic, the ageing and tempering of two Fe-Ni-C alloys have been characterised by means of atom probe tomography and synchrotron radiation diffraction. Upon ageing at room temperature, carbon redistribution is clearly observed, where the process of carbon segregation to defects appears to be most likely to occur. Nevertheless, the possibility of spinodal decomposition is not entirely discarded, and the current work presents a series of discussion points that challenge our current understanding of the thermodynamic of ferrite in steels. ARTICLE HISTORY

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Dislocation interaction with C in α-Fe: A comparison between atomic simulations and elasticity theory

Cited by 194 publications

References 41 publications

Solute strengthening in random alloys

Solute strengthening in random alloys

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

Thermodynamic aspects of carbon redistribution during ageing and tempering of Fe–Ni–C alloys

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