A unified approach to motion of grain boundaries, relative tangential translation along grain boundaries, and grain rotation

Cahn, John W.; Taylor, Jean E.

doi:10.1016/j.actamat.2004.02.048

Cited by 427 publications

(389 citation statements)

References 15 publications

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“…Moreover, the coupling shear is able to drastically decrease the minimum value of energy change. The critical shear stress τ c for initiating the dislocation emission process can be reduced significantly due to the existence of coupled shear during the migration process, especially in the case of high-angle boundary; and it is important to note that there is a critical coupling factor β c that corresponds to the minimum τ c , which indicates that the dislocations in NC materials can possibly be maximized by engineering the GB structure to obtain an appropriate value of β [31,33]. The predicted critical shear stress for initiating multiple dislocations that emit from disclinated GBs into grain interiors in multiple slip systems has also been validated by the existing MD simulations for a nanocrystalline Cu sample of 10 nm grain size.…”

Section: Discussionmentioning

confidence: 99%

“…This athermal process [20] normally consists of a normal GB migration accompanied by a tangential translation of grains parallel to the GB plane for both low-angle and high-angle boundaries; the process would then produce shear deformation of the lattice traversed by the migrated GB. The translation distance s is related to the normal migration distance m by a coupling factor β ¼ s=m [31]. The value of β is determined by the geometry of the GB concerned [31,32], and the maximum value of β can reach 1 based on experiments [27,33] and MD simulations [25,32] and reach 5 according to theoretical studies [34,35].…”

Section: Introductionmentioning

confidence: 99%

“…The translation distance s is related to the normal migration distance m by a coupling factor β ¼ s=m [31]. The value of β is determined by the geometry of the GB concerned [31,32], and the maximum value of β can reach 1 based on experiments [27,33] and MD simulations [25,32] and reach 5 according to theoretical studies [34,35]. The coupled mode has been revealed as a very effective toughening mechanism in NC materials [36] and it can considerably enhance the intrinsic ductility of NC materials by incorporating with the conventional GB sliding process [37].…”

Section: Introductionmentioning

confidence: 99%

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Enhancing dislocation emission in nanocrystalline materials through shear-coupled migration of grain boundaries

Soh

2014

Materials Science and Engineering: A

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a b s t r a c tA theoretical model has been developed to illustrate the effect of shear-coupled migration of grain boundaries on dislocation emission in nanocrystalline materials. The energy characteristics and critical shear stress τ c that is required to initiate the emission process were determined. The results obtained show that the dislocation emission can be considerably enhanced as shear-coupled migration was the dominating process; a critical coupling factor that corresponded to the minimum τ c , which led to an optimal dislocation emission, was also discovered. The proposed model has also been quantitatively validated by the existing molecular dynamics simulations.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Enhancing dislocation emission in nanocrystalline materials through shear-coupled migration of grain boundaries

Soh

2014

Materials Science and Engineering: A

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“…[2,7,14,18,20,21,24,31] Noteworthy, however, is the fact that most published theoretical and experimental papers related to stressinduced grain growth focus on single-phase materials and as a result, material systems containing secondphase particles have been rarely reported. Moreover, although many materials that contain a high level of solute segregation at GBs are selected as model materials for studies of stress-induced grain growth, [5,9,11,32,33] the influence of solute atoms segregated at GBs on stress-induced grain growth has been investigated only in very limited cases.…”

Section: Stress-induced Grain Growth Has Attractedmentioning

confidence: 99%

Erratum to: Stress-Induced Grain Growth in an Ultra-Fine Grained Al Alloy

Lin

Wen

Liu

et al. 2014

Metall Mater Trans B

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This paper reports on a study of the stress-induced grain growth phenomenon in the presence of second-phase particles and solutes segregated at grain boundaries (GBs) during high-temperature deformation of an ultra-fine grained (UFG) Al alloy synthesized via the consolidation of mechanically milled powders. Our results show that grain growth was essentially inhibited during annealing at 673 K (400°C) in the absence of an externally applied stress, whereas in contrast, grain growth was enhanced by a factor of approximately 2.7 during extrusion at 673 K (400°C). These results suggest that significant grain growth during hot extrusion was attributable to the externally applied stresses stemming from the state of stress imposed during extrusion and that the externally applied stresses can overcome the resistance forces generated by second-phase particles and solutes segregated at GBs. The mechanisms underlying stressinduced grain growth were identified as GB migration and grain rotation, which were accompanied by dynamic recovery and possible geometric dynamic recrystallization, while discontinuous dynamic recrystallization did not appear to be operative. His research interests include the synthesis and behavior of nanostructured and multi-scale materials with particular emphasis on processing fundamentals and physical behavior; thermal spray processing of nanostructured materials; spray atomization and deposition of structural materials; high temperature-high pressure atomization processes; mathematical modeling of advanced materials and processes; and additive manufacturing. He has published 515 journal and 225 conference publications on topics ranging from nanomaterials to extremely strong aluminum alloys. Prof. Lavernia has delivered more than 150 invited lectures and seminars in over 17 countries. He

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“…Only recently this phenomenon has started to attract much attention and to be systematically studied either through experiments [8][9][10][11][12][13], or theoretically [14] or by numerical simulations [15][16][17][18][19][20]. We refer here to stress/strain coupled GB migration (limited in fact to shear-coupled migration of tilt boundaries or associated to the tilt component of grain boundaries), not to be mistaken with "strain-induced GB migration", a term used since early recrystallization studies to denote the preferred migration of a GB separating two grains with a very different strain-induced dislocation density [21,22].…”

Section: Introductionmentioning

confidence: 99%

Plastic deformation by conservative shear-coupled migration of tilt boundaries with intergranular nano-cracks or precipitates

Luque

Aldazábal

Martı́nez-Esnaola

et al. 2010

Philosophical Magazine

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. Plastic deformation by conservative shear-coupled migration of tilt boundaries with intergranular nanocracks or precipitates. Philosophical Magazine, Taylor & Francis, 2010, 90 (27-28) We present molecular dynamics (MD) simulations of the shear-coupled migration (SCM) behaviour of symmetrical tilt boundaries perturbed by the presence of nano-cracks or nano-precipitates lying on the boundary plane. The simulations have been performed for copper bicrystals at room temperature (300 K). The tilt boundary gets pinned by the crack tip or by the precipitates; shear-coupled migration occurs only ahead of the pinning points. Bulging of the tilt boundary reduces the shear stress on the boundary surface near the pinning points. In the case of cracks the local deviation of the boundary from the crack plane close to the crack tip hinders mode II crack propagation; in fact, some crack healing is observed in some cases. The applied stress grows until depinning of the boundary takes place by SCM bulging or by the combined action of SCM with another deformation mechanism (emission of dislocations from the pinning point vicinity, grain boundary sliding).

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A unified approach to motion of grain boundaries, relative tangential translation along grain boundaries, and grain rotation

Cited by 427 publications

References 15 publications

Enhancing dislocation emission in nanocrystalline materials through shear-coupled migration of grain boundaries

Enhancing dislocation emission in nanocrystalline materials through shear-coupled migration of grain boundaries

Erratum to: Stress-Induced Grain Growth in an Ultra-Fine Grained Al Alloy

Plastic deformation by conservative shear-coupled migration of tilt boundaries with intergranular nano-cracks or precipitates

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