Strategies to Approach Stabilized Plasticity in Metals with Diminutive Volume: A Brief Review

Hu, Tao; Mukherjee, Amiya K.; Schoenung, Julie M.; Lavernia, Enrique J.

doi:10.3390/cryst6080092

Cited by 5 publications

(5 citation statements)

References 44 publications

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“…For example, for fiber-structured materials, one may imagine that avalanches get 'arrested'. In a similar way, it could happen that similar 'arrest' takes place in nano-grained materials at grain boundaries, such as reviewed in section 4 in [284] and [47,102,103]. It is therefore tantalizing to think of how we can exploit the physics of strain bursts and dislocation avalanches to design the ultimate materials that are extremely strong and ductile at the same time!…”

Section: Conclusion and Future Prospectsmentioning

confidence: 96%

Avalanches and plastic flow in crystal plasticity: an overview

Papanikolaou

Cui

Ghoniem

2017

Modelling Simul. Mater. Sci. Eng.

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Crystal plasticity is mediated through dislocations, which form knotted configurations in a complex energy landscape. Once they disentangle and move, they may also be impeded by permanent obstacles with finite energy barriers or frustrating long-range interactions. The outcome of such complexity is the emergence of dislocation avalanches as the basic mechanism of plastic flow in solids at the nanoscale. While the deformation behavior of bulk materials appears smooth, a predictive model should clearly be based upon the character of these dislocation avalanches and their associated strain bursts. We provide here a comprehensive overview of experimental observations, theoretical models and computational approaches that have been developed to unravel the multiple aspects of dislocation avalanche physics and the phenomena leading to strain bursts in crystal plasticity.

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Section: Conclusion and Future Prospectsmentioning

confidence: 96%

Avalanches and plastic flow in crystal plasticity: an overview

Papanikolaou

Cui

Ghoniem

2017

Modelling Simul. Mater. Sci. Eng.

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“…In other words, despite the extremely high strength achievable at ultra-small scales, the corresponding plastic flows turned out to be uncontrollable due to the stochastic nature of strain bursts reminiscent of macroscopic earthquakes. The disastrous dislocation avalanches not only poison the forming processes but also compromise the load-carrying capacity in various engineering/industrial processes dealing with sub-µm parts, including nanoimprint lithography [118] and shaping of MEMS [37]. An urgent challenge facing today's metallurgy at sub-µm scales is, therefore, to reduce the "wildness" of the associated fluctuations, while keeping or improving other properties, such as strength.…”

Section: Discussionmentioning

confidence: 99%

“…This became a bigger issue when it was realized that, upon decreasing the system size below few µm-noticeably, the same order of magnitude as the characteristic scale l p -, plastic deformation becomes jerky independently of crystal symmetry [4,34,35]. It raised major concerns regarding manufacturing and reliable utilization of ultrasmall machinery [36,37]. By construction, the phenomenological continuum models and field theories are unable to deal with such fluctuations, unless stochastic closures are implemented implicitly [38,39].…”

Section: Continuum Mechanics Versus Discrete Approachesmentioning

confidence: 99%

“…However, as we detailed above, such effect at small scale is accompanied by a detrimental "smaller is wilder" effect. The latter is culminating in brittleness at nanoscale (see above), which may compromise the forming processes and endanger the load-carrying capacity in various engineering/industrial processes taking place in such samples [37,118]. A key challenge is therefore to develop new metallurgical procedures to mitigate the associated plastic instabilities and reduce/suppress their detrimental effects, while preserving all the advantages related to high strength.…”

Section: Alloysmentioning

confidence: 99%

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Fluctuations in crystalline plasticity

Weiss¹,

Zhang²,

Salman³

et al. 2021

Comptes Rendus. Physique

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Recently acoustic signature of dislocation avalanches in HCP materials was found to be long tailed in size and energy, suggesting critical dynamics. Moreover, the intermittent plastic response was found to be generic for micro-and nano-sized systems independently of their crystallographic symmetry. These rather remarkable discoveries are reviewed in this paper in the perspective of the recent studies performed in our group. We discuss the physical origin and the scaling properties of plastic fluctuations and address the nature of their dependence on crystalline symmetry, system size, and disorder content. A particular emphasis is placed on the formation of dislocation structures, and on our ability to temper plastic fluctuations by alloying. We also discuss the "smaller is wilder" size effect that culminates in a paradoxical crack-free brittle behavior of very small, initially dislocation free crystals. We argue that the implied transition between different rheological behaviors is regulated by the ratio of length scales R = L/l , where L is the system size and l is the internal length. We link this size effect with size dependence of strength ("smaller is stronger") and the size-induced switch between different hardening mechanisms. We show that the task of taming the intermittency of plastic flow at ultra-small scales can be accomplished by generating tailored quenched disorder which allows one to control micro-and nano-forming and opens new perspectives in micro-metallurgy and structural engineering of miniature load-carrying elements. These insights were beyond the reach of conventional theoretical approaches that do not explicitly account for the stochastic nature of collective dislocation dynamics.

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“…Furthermore, mild and wild fluctuations can coexist during plastic deformation [5]. The wildness of dislocation-mediated plasticity is associated with size effects: In materials characterized by a mild plasticity at large scales, such as in FCC metals, deformation becomes wild for sub-µm sample sizes [6,7], signing a "smaller is wilder" size effect [8] with potential detrimental effects for micro/nanoscale engineering [9,10]. Wildness also depends on an internal length scale that emerges from dislocations with mutual interactions in pure metals.…”

Section: Introductionmentioning

confidence: 99%

Twisting of pre-twinned α-Fe nanowires: from mild to wild avalanche dynamics

Yang

Ding

et al. 2020

Acta Materialia

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We studied the torsion behavior of -Fe nanowires seeded with twin boundaries (TBs) using molecular dynamics simulations. Twisting the wire generates topological defects in the twin walls, namely kinks inside the twin walls for small twist angles, and junctions between kinks for large twist angles. During twisting the kink motion is jerky and uncorrelated at small twist angles. The probability density function (PDF) of jerk energies follows approximately a Gaussian distribution, indicating a mild deformation mode. The kink dynamics transforms from mild to wild at larger twist angles when complex twin patterns with a high density of junctions are generated. The collective motion of kinks now shows avalanche behavior with the energy being power-law distributed. The wildness, which measures the proportion of strain energy relaxed through such avalanches, is correlated with the junction density, and controlled by the external length scale (wire diameter) as well as an internal length scale (twin boundary spacing). Good strain-stress recoverability is achieved when unloading the wire before the formation of complex twin patterns. We correlate the evolution of twin patterns with a statistical analysis of jerk dynamics, which identifies the unique mechanical properties governed by twin boundary motion in nanowires.

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Strategies to Approach Stabilized Plasticity in Metals with Diminutive Volume: A Brief Review

Cited by 5 publications

References 44 publications

Avalanches and plastic flow in crystal plasticity: an overview

Avalanches and plastic flow in crystal plasticity: an overview

Fluctuations in crystalline plasticity

Twisting of pre-twinned α-Fe nanowires: from mild to wild avalanche dynamics

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