Dynamics of grain boundaries under applied mechanical stress

Molodov, Dmitri A.; Gorkaya, Tatiana; Gottstein, Günter

doi:10.1007/s10853-010-5233-6

Cited by 112 publications

(87 citation statements)

References 36 publications

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“…The presence of equiaxed and dislocation free (sub)grains with thin smooth boundaries (figure 1f) suggests the development of recovery and even recrystallization processes that seems to be quite unusual for such a low temperature. However, high stresses can in some cases compensate for the insufficient thermal activation and induce local migration of grain boundaries and recrystallization [8][9][10].…”

Section: Microstructure Evolution In Timentioning

confidence: 99%

Twinning induced nanostructure formation during cryo-deformation

Klimova

D’yakonov

Zherebtsov

et al. 2014

IOP Conf. Ser.: Mater. Sci. Eng.

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Abstract. In the present work the influence of cryo-rolling to a true strain ε=2.66 on twinning and formation of ultrafine-grained/nanostructure in commercial-purity titanium and Fe-0.3C-23Mn-1.5Al TWIP steel was quantified using scanning and transmission electron microscopy. Different influence of twinning on the kinetics of microstructure refinement and nanostructure formation in titanium and steel was revealed. In titanium twin boundaries during deformation transform into arbitrary high-angle grain boundaries thereby promoting the microstructure refinement to a grain/subgrain size of 80 nm. In steel twinning has less pronounced influence on the microstructure refinement. However, very fine grains/subgrains with the size of 30-50 nm was observed in the microstructure after rolling at 77K to a true thickness strain of 2.66.

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Section: Microstructure Evolution In Timentioning

confidence: 99%

Twinning induced nanostructure formation during cryo-deformation

Klimova

D’yakonov

Zherebtsov

et al. 2014

IOP Conf. Ser.: Mater. Sci. Eng.

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“…In contrast, a low angle dry GB with intact solid bridges in between isolated dislocations with premelted cores would be expected to support shear more like a static solid. However, both theoretical [32][33][34][35][36] and experimental [37][38][39] studies over the last decade have shown that a dry GB generically moves normal to itself under an applied shear stress. This motion coupled to shear, commonly referred to as "coupled motion", is characterized by a relationship v = βv n between the translation velocity of the two grains parallel to the GB plane, v , and the GB velocity normal to this plane, v n .…”

Section: Introductionmentioning

confidence: 99%

Phase-field-crystal study of grain boundary premelting and shearing in bcc iron

et al. 2013

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We use the phase-field-crystal (PFC) method to investigate the equilibrium premelting and nonequilibrium shearing behaviors of [001] symmetric tilt grain boundaries (GBs) at high homologous temperature over the complete range of misorientation 0 < θ < 90 • in classical models of bcc Fe. We characterize the dependence of the premelted layer width W as a function of temperature and misorientation. In addition, we compute the thermodynamic disjoining potential whose derivative with respect to W represents the structural force between crystal-melt interfaces due to the spatial overlap of density waves. The disjoining potential is also computed by molecular dynamics (MD) simulations, for quantitative comparison with PFC simulations, and coarse-grained amplitude equations (AE) derived from PFC that provide additional analytical insights. We find that, for GBs over an intermediate range of misorientation (θmin < θ < θmax), W diverges as the melting temperature is approached from below, corresponding to a purely repulsive disjoining potential, while for GBs outside this range (θ < θmin or θmax < θ < 90 • ), W remains finite at the melting point. In the latter case, W corresponds to a shallow attractive minimum of the disjoining potential. The misorientation range where W diverges predicted by PFC simulations is much smaller than the range predicted by MD simulations when the small dimensionless parameter ǫ of the PFC model is matched to liquid structure factor properties. However it agrees well with MD simulations with a lower ǫ value chosen to match the ratio of bulk modulus and solid-liquid interfacial free-energy, consistent with the amplitude-equation prediction that θmin and 90 • − θmax scale as ∼ ǫ 1/2 . The incorporation of thermal fluctuations in PFC is found to have a negligible effect on this range. In response to a shear stress parallel to the GB plane, GBs in PFC simulations exhibit coupled motion normal to this plane or sliding. Furthermore, the coupling factor exhibits a discontinuous change as a function of θ that reflects a transition between two coupling modes. Sliding is only observed over a range of misorientation that is a strongly increasing function of temperature for T /TM ≥ 0.8 and matches roughly the range where W diverges at the melting point. The coupling factor for the two coupling modes is in excellent quantitative agreement with previous theoretical predictions [J. W. Cahn, Y. Mishin, and A. Suzuki, Acta Mater. 54, 4953 (2006)].

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“…The formation of large facetted crystals during grain growth and dewetting of thin films during hydrogenation of Mg also suggests the importance of stress-induced coarsening to thin-film stability in the presence of a phase change. 106 Research on modeling and measuring stress generation and relaxation in thin films by competing processes during thin-film formation, 115 thermal cycling, 116 applied stresses, 107,117 or isothermal stress generation processes, such as intermetallic formation during room-temperature annealing of Sn films on Cu, [118][119][120][121] is revealing the role of microstructural heterogeneity and crystalline anisotropy on the response of different thin films to stress. Further progress will require a more detailed understanding of how grain boundaries and interfaces migrate and respond to applied stresses, the mechanisms and conditions for coupling stress and grain boundary motion, and the ability of grain boundaries and surfaces to act as vacancy sources and sinks for diffusional creep.…”

Section: Functionality and Control Of Materials Far From Equilibriummentioning

confidence: 99%

Emerging Science and Research Opportunities for Metals and Metallic Nanostructures

Handwerker

Pollock

2014

JOM

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During the next decade, fundamental research on metals and metallic nanostructures (MMNs) has the potential to continue transforming metals science into innovative materials, devices, and systems. A workshop to identify emerging and potentially transformative research areas in MMNs was held June 13 and 14, 2012, at the University of California Santa Barbara. There were 47 attendees at the workshop (listed in the Acknowledgements section), representing a broad range of academic institutions, industry, and government laboratories. The metals and metallic nanostructures (MMNs) workshop aimed to identify significant research trends, scientific fundamentals, and recent breakthroughs that can enable new or enhanced MMN performance, either alone or in a more complex materials system, for a wide range of applications. Additionally, the role that MMN research can play in high-priority research and development (R&D) areas such as the U.S. Materials Genome Initiative, the National Nanotechnology Initiative, the Advanced Manufacturing Initiative, and other similar initiatives that exist internationally was assessed. The workshop also addressed critical issues related to materials research instrumentation and the cyberinfrastructure for materials science research and education, as well as science, technology, engineering, and mathematics (STEM) workforce development, with emphasis on the United States but with an appreciation that similar challenges and opportunities for the materials community exist internationally. A central theme of the workshop was that research in MMNs has provided and will continue to provide societal benefits through the integration of experiment, theory, and simulation to link atomistic, nanoscale, microscale, and mesoscale phenomena across time scales for an ever-widening range of applications. Within this overarching theme, the workshop participants identified emerging research opportunities that are categorized and described in more detail in the following sections in terms of the following: three-dimensional (3-D) and fourdimensional (4-D) materials science. Structure evolution and the challenge of heterogeneous and multicomponent systems. The science base for property prediction across the length scales. Nanoscale phenomena at surfaces-experiment, theory, and simulation. Prediction and control of the morphology, microstructure, and properties of ''bulk'' nanostructured metals. Functionality and control of materials far from equilibrium. Hybrid and multifunctional materials assemblies. Materials discovery and design: enhancing the theory-simulation-experiment loop. Following an introduction, these emerging research opportunities are discussed in detail, along with challenges and opportunities for the materials community in the areas of instrumentation, cyberinfrastructure, education, and workforce development.

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Dynamics of grain boundaries under applied mechanical stress

Cited by 112 publications

References 36 publications

Twinning induced nanostructure formation during cryo-deformation

Twinning induced nanostructure formation during cryo-deformation

Phase-field-crystal study of grain boundary premelting and shearing in bcc iron

Emerging Science and Research Opportunities for Metals and Metallic Nanostructures

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