Role of the mesoscale in migration kinetics of flat grain boundaries

Race, Christopher; Pezold, J. von; Neugebauer, Jörg

doi:10.1103/physrevb.89.214110

Cited by 44 publications

(49 citation statements)

References 50 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The periodic boundary conditions can also introduce artificial correlations within the grain boundary plane. As shown recently, these artificial correlations can alter the migration mechanisms if the lateral supercell dimensions are too small [14]. Extensive benchmarks showed that this is less of a problem for our nonsymmetric grain boundary structures where the small misorientation angles from the symmetric boundary result in large lateral dimensions of the CSL unit cells.…”

Section: Simulation Methodsmentioning

confidence: 68%

“…The mesoscale island nucleation model proposed in Ref. [14] accurately reproduces the temperature dependence of the velocity below the roughening temperature using only two fitting parameters [see the dashed lines in Fig. 3(a)].…”

Section: B Migration Kineticsmentioning

confidence: 79%

“…It was shown in Ref. [14] that the nucleation mechanism for a flat boundary is the formation of islands of atoms with the orientation of the growing grain. At higher temperatures [700 K; Fig.…”

Section: B Migration Kineticsmentioning

confidence: 99%

“…One reason may be that the computational constraints have limited these calculations to rather small supercells. As has been discussed in a recent study [14] small supercell sizes may inhibit the formation of the correct dynamical mesostructure with the consequence that unphysical mechanisms prevail and determine the rate of boundary migration, particularly when approaching the comparatively small driving forces characteristic of experimental cases. Another typical limitation of MD simulations has been the restriction to symmetric tilt boundaries.…”

mentioning

confidence: 97%

See 3 more Smart Citations

Atomistic migration mechanisms of atomically flat, stepped, and kinked grain boundaries

et al. 2016

Self Cite

View full text Add to dashboard Cite

We studied the migration behavior of mixed tilt and twist grain boundaries in the vicinity of a symmetric tilt 111 7 grain boundary in aluminum. We show that these grain boundaries fall into two main categories of stepped and kinked grain boundaries around the atomically flat symmetric tilt boundary. Using these structures together with size converged molecular dynamics simulations and investigating snapshots of the boundaries during migration, we obtain an intuitive and quantitative description of the kinetic and atomistic mechanisms of the migration of general mixed grain boundaries. This description is closely related to well-known concepts in surface growth such as step and kink-flow mechanisms and allows us to derive analytical kinetic models that explain the dependence of the migration barrier on the driving force. Using this insight we are able to extract energy barrier data for the experimentally relevant case of vanishing driving forces that are not accessible from direct molecular dynamics simulations and to classify arbitrary boundaries based on their mesoscopic structures. DOI: 10.1103/PhysRevB.94.165413 I. MOTIVATIONThe migration of grain boundaries plays a pivotal role in the evolution of materials microstructures, which strongly impacts the mechanical, chemical, or electronic response of a material. Thus, for designing optimized materials with tailored microstructures, a detailed understanding of grain boundary kinetics and of the underlying atomistic mechanisms is crucial. Identifying these fundamental mechanisms and understanding their impact on grain boundary migration has been a key topic both from an experimental as well as a theoretical perspective for several decades.In 1948 Mott [1] proposed that the migration is a thermally activated process. In his model for migration, the energy barrier that the boundary must overcome is related to an island nucleation mechanism where atoms melt on one side of the boundary and solidify on the other crystalline side. In 1969 Gleiter portrayed a general grain boundary as a 3D stepped structure by interpreting diffraction contrast microscopy images [2,3]. He proposed that general nonsymmetric grain boundaries are not atomically flat but are rather comprised of atomic steps and kinks, similar to the well-known structural elements on surfaces. He also pointed out that the boundary moves via the emission and absorption of atoms at step kinks.The picture of both Mott [1] and Gleiter [2,3] that grain boundaries consist of an intermediate layer changed with the advent of high-resolution electron microscopy which showed that the interface region is rather sharp [4]. In the late 1970s several electron microscopic studies analyzed grain boundary migration in terms of the motion of secondary grain boundary dislocations [5][6][7]. However a more recent in situ electron microscopy work by Babcock and Balluffi [8] in 1989 showed the contribution from the dislocation motion to be negligible. In their study [8] of curvature-driven grain boundary migration in near 5 bound...

show abstract

Section: Simulation Methodsmentioning

confidence: 68%

Section: B Migration Kineticsmentioning

confidence: 79%

Section: B Migration Kineticsmentioning

confidence: 99%

mentioning

confidence: 97%

See 2 more Smart Citations

Atomistic migration mechanisms of atomically flat, stepped, and kinked grain boundaries

et al. 2016

Self Cite

View full text Add to dashboard Cite

show abstract

“…The coupling factor β = d m characterizes this migration. Despite experimental investigations [7][8][9] and recent theoretical studies [10][11][12][13][14][15][16], the details of the shear-coupled migration mechanisms remain poorly known.…”

Section: Introductionmentioning

confidence: 99%

Disconnections kinks and competing modes in shear-coupled grain boundary migration

2016

View full text Add to dashboard Cite

The response of small-grained metals to mechanical stress is investigated by a theoretical study of the elementary mechanisms occurring during the shear-coupled migration of grain boundaries (GB). Investigating a model 17(410) GB in a copper bicrystal, both 110 and 100 GB migration modes are studied focusing on both the structural and energetic characteristics. The minimum energy paths of these shear-coupled GB migrations are computed using the nudge elastic band method. For both modes, the GB migration occurs through the nucleation and motion of disconnections. However, the atomic mechanisms of both modes qualitatively differ: While the 110 mode presents no metastable state, the 100 mode shows multiple metastable states, some of them evidencing some kinks along the disconnection lines. Disconnection kinks nucleation and motion activation energies are evaluated. Besides, the activation energies of the 100 mode are smaller than those of the 110 one except for very high stresses. These results significantly improve our knowledge of the GB migration mechanisms and the conditions under which they occur.

show abstract

Review of thermo‐kinetic correlation during grain growth in nanocrystalline materials

Peng

Jian

Liu

2020

Int J Ceramic Engine & Sci

View full text Add to dashboard Cite

Nanocrystalline (NC) materials exhibit many unique properties over their coarse‐grained counterparts due to the high grain boundary density and the small grain size, but they are too difficult to be used in engineering environment because of the poor thermal stability. With regard of this, two strategies are previously proposed to enhance the thermal stability (or impede the grain growth) of NC materials, that is, the thermodynamic and the kinetic approaches. Recent investigations increasingly support that the two approaches may be physically interacted and acted on each other, and they can be treated together within a unified thermo‐kinetic framework. This paper reviews the progress in the investigation of thermo‐kinetic correlation during grain growth in NC materials. First, the theoretical models to describe the concept of the thermo‐kinetic correlation and the grain growth equations developed based on the thermo‐kinetic correlation are reviewed. Second, experimental and simulated evidences to support the coexistence of thermodynamic and kinetic effects are summarized. Third, the potential application of thermo‐kinetic correlation is analyzed and discussed. This paper shows that the stabilization of NC materials can be tailored by the selection of the suitable strategies. Finally, several directions that require further exploration are identified.

show abstract

Role of the mesoscale in migration kinetics of flat grain boundaries

Cited by 44 publications

References 50 publications

Atomistic migration mechanisms of atomically flat, stepped, and kinked grain boundaries

Atomistic migration mechanisms of atomically flat, stepped, and kinked grain boundaries

Disconnections kinks and competing modes in shear-coupled grain boundary migration

Review of thermo‐kinetic correlation during grain growth in nanocrystalline materials

Contact Info

Product

Resources

About