Ab initio modeling of dislocation core properties in metals and semiconductors

Rodney, David; Ventelon, Lisa; Clouet, Emmanuel; Pizzagalli, Laurent; Willaime, F.

doi:10.1016/j.actamat.2016.09.049

Cited by 240 publications

(142 citation statements)

References 299 publications

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“…Fixing σ = 1.5b, the dimensionless pressure field f (x i , y j ) can then be computed, and the minimized quantities in brackets in Eqs. (25) and (26) When both gaussian peaks are well separated, i.e. when d > 10b, there are two minimum energy configurations leading to two different minimized coefficients for both zero-temperature stress and energy barrier.…”

Section: Discussionmentioning

confidence: 99%

“…(25) and (26) can be related -under certain conditions -to the so-called "lattice misfit parameter" δ. Specifically, neglecting the fluctuations in solute/dislocation interactions, assuming that all alloying elements can crystallize in the same structure, and assuming that Vegard's law is followed for the lattice parameter variations with alloy composition, the misfit parameter is δ = n c n ∆V 2 n /3V , with V the atomic volume of the average matrix.…”

Section: Elastic Interaction Modelmentioning

confidence: 99%

“…(25) and (26) sured alloy contributions σ alloy to the yield stress for the NiCoFeCr and NiCoFeCrMn alloys over the complete temperature range atε = 10 −3 s −1 . The predictions are very good, again with no fitting parameters.…”

Section: Fcc High Entropy Alloysmentioning

confidence: 99%

“…Such an approach is then coupled with predictions of alloy phase stability through wellestablished thermodynamic modeling. For dilute alloys, ab initio computation of dislocation core structure and solute/dislocation interaction is accessible with high accuracy, as described in the partner Overview article [25]. The line tension is computable from either empirical potential simulations (given good interatomic potentials) or from DFT-parameterized line tension models [82,103].…”

Section: Identification Of Promising Materialsmentioning

confidence: 99%

“…This interaction will be discussed in section 4.3. With the advent of high-performance computing, and efficient techniques to deal with the longrange elastic fields of dislocations [22,23,24], it is now possible to compute dislocation core structures using first-principles methods, most commonly using Density Functional Theory (DFT). This topic is covered in depth in the partner Overview Arti-cle "Ab initio modeling of dislocation core properties" [25]. Using the same methods, the solute/dislocation interaction energies U (x i , y j ) for any solute at atomic positions {x i , y j } in and around a dislocation core in any matrix can be computed directly.…”

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: Discussionmentioning

confidence: 99%

Section: Elastic Interaction Modelmentioning

confidence: 99%

Section: Fcc High Entropy Alloysmentioning

confidence: 99%

Section: Identification Of Promising Materialsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Solute strengthening in random alloys

et al. 2017

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Tailoring the Plasticity of Topologically Close‐Packed Phases via the Crystals’ Fundamental Building Blocks

et al. 2023

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Brittle topologically close‐packed precipitates form in many advanced alloys. Due to their complex structures, little is known about their plasticity. Here, a strategy is presented to understand and tailor the deformability of these complex phases by considering the Nb–Co µ‐phase as an archetypal material. The plasticity of the Nb–Co µ‐phase is controlled by the Laves phase building block that forms parts of its unit cell. It is found that between the bulk C15–NbCo2 Laves and Nb–Co µ‐phases, the interplanar spacing and local stiffness of the Laves phase building block change, leading to a strong reduction in hardness and stiffness, as well as a transition from synchroshear to crystallographic slip. Furthermore, as the composition changes from Nb6Co7 to Nb7Co6, the Co atoms in the triple layer are substituted such that the triple layer of the Laves phase building block becomes a slab of pure Nb, resulting in inhomogeneous changes in elasticity and a transition from crystallographic slip to a glide‐and‐shuffle mechanism. These findings open opportunities to purposefully tailor the plasticity of these topologically close‐packed phases in the bulk by manipulating the interplanar spacing and local shear modulus of the fundamental crystal building blocks at the atomic scale.

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Valence energy correction for electron reactive force field

Bertolini

Jacob

2022

J Comput Chem

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Reactive force fields (ReaxFF) are a classical method to describe material properties based on a bond‐order formalism, that allows bond dissociation and consequently investigations of reactive systems. Semiclassical treatment of electrons was introduced within ReaxFF simulations, better known as electron reactive force fields (eReaxFF), to explicitly treat electrons as spherical Gaussian waves. In the original version of eReaxFF, the electrons and electron–holes can lead to changes in both the bond energy and the Coulomb energy of the system. In the present study, the method was modified to allow an electron to modify the valence energy, therefore, permitting that the electron's presence modifies the three‐body interactions, affecting the angle among three atoms. When a reaction path involving electron transfer is more sensitive to the geometric configuration of the molecules, corrections in the angular structure in the presence of electrons become more relevant; in this case, bond dissociation may not be enough to describe a reaction path. Consequently, the application of the extended eReaxFF method developed in this work should provide an improved description of a reaction path. As a first demonstration this semiclassical force field was parametrized for hydrogen and oxygen interactions, including water and water's ions. With the modified methodology both the overall accuracy of the force field but also the description of the angles within the molecules in presence of electrons could be improved.

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Ab initio modeling of dislocation core properties in metals and semiconductors

Cited by 240 publications

References 299 publications

Solute strengthening in random alloys

Solute strengthening in random alloys

Tailoring the Plasticity of Topologically Close‐Packed Phases via the Crystals’ Fundamental Building Blocks

Valence energy correction for electron reactive force field

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