Scaling of relaxation and excess entropy in plastically deformed amorphous solids

Galloway, K. Lawrence; Ma, Xiuhua; Keim, Nathan C.; Jerolmack, D. J.; Yodh, Arjun G.; Arratia, Paulo E.

doi:10.1073/pnas.2000698117

Cited by 21 publications

(12 citation statements)

References 55 publications

(81 reference statements)

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“…Intuitively, the condition b = c should correspond to mechanical equilibrium, with no imposed shear stress in either direction. However, Galloway et al (39,40) found that an elliptical signature could be detected even at equilibrium and that it survived further shear deformations below the yielding transition, so that its disappearance was a proxy for yielding. They identified it as the memory of an earlier large plastic deformation, consistent with scattering results from bulk metallic glasses that were previously deformed (4,41,42).…”

Section: Effect Of Annealing On Microscopic Structurementioning

confidence: 99%

Mechanical annealing and memories in a disordered solid

Keim

Medina

2022

Sci. Adv.

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Shearing a disordered or amorphous solid for many cycles with a constant strain amplitude can anneal it, relaxing a sample to a steady state that encodes a memory of that amplitude. This steady state also features a remarkable stability to amplitude variations that allows one to read the memory. Here, we shed light on both annealing and memory by considering how to mechanically anneal a sample to have as little memory content as possible. In experiments, we show that a “ring-down” protocol reaches a comparable steady state but with no discernible memories and minimal structural anisotropy. We introduce a method to characterize the population of rearrangements within a sample and show how it connects with the response to amplitude variation and the size of annealing steps. These techniques can be generalized to other forms of glassy matter and a wide array of disordered solids, especially those that yield by flowing homogeneously.

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Section: Effect Of Annealing On Microscopic Structurementioning

confidence: 99%

Mechanical annealing and memories in a disordered solid

Keim

Medina

2022

Sci. Adv.

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“…Intuitively, the condition b = c should correspond to mechanical equilibrium, with no imposed shear stress in either direction. However Galloway et al (39,40) found that an elliptical signature could be detected even at equilibrium, and that it survived further shear deformations below the yielding transition. They identified it as the memory of an earlier large plastic deformation-consistent with scattering results from bulk metallic glasses that were previously deformed (5,41,42).…”

Section: Effect Of Annealing On Microscopic Structurementioning

confidence: 99%

Mechanical annealing and memories in a disordered solid

Keim¹,

Medina²

2021

Preprint

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Shearing a disordered or amorphous solid for many cycles with a constant strain amplitude can anneal it, relaxing a sample to a steady state that encodes a memory of that amplitude. This steady state also features a remarkable stability to amplitude variations that allows one to read the memory. Here we shed new light on both annealing and memory, by considering how to mechanically anneal a sample to have as little memory content as possible. In experiments, we show that a "ring-down" protocol reaches a comparable steady state, but with no discernible memories and minimal structural anisotropy. We introduce a method to characterize the population of rearrangements within a sample, and show how it connects with the response to amplitude variation and the size of annealing steps. These techniques can be generalized to other forms of glassy matter and a wide array of disordered solids, especially those that yield by flowing homogeneously.

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“…Even though S 2 has been introduced long ago 54,55 , it is a useful concept that continues to be widely used 17,[56][57][58] . As a matter of fact, recently, scaling relations have been reported between S 2 and diffusivity in glassy systems 59 and relaxation rates in cyclic sheared systems 60 . In order to look at this quantity on a single-particle level, the two-body entropy of particle i can be defined as:…”

Section: Local Entropymentioning

confidence: 99%

Correlation between plastic rearrangements and local structure in a cyclically driven glass

Mitra,

Marin-Aguilar,

Sastry

et al. 2021

Preprint

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The correlation between local structure and the propensity for structural rearrangements has been widely investigated in glass forming liquids and glasses. In this paper we use the excess two-body entropy S 2 and tetrahedrality n tet as the per-particle local structural order parameters to explore such correlations in a three-dimensional model glass subjected to cyclic shear deformation. We first show that for both liquid configurations and the corresponding inherent structures, local ordering increases upon lowering temperature, signaled by a decrease in the two-body entropy and an increase in tetrahedrality. When the inherent structures, or glasses, are periodically sheared athermally, they eventually reach absorbing states for small shear amplitudes, which do not change from one cycle to the next. Large strain amplitudes result in the the formation of shear bands, within which particle motion is diffusive. We show that in the steady state, there is a clear difference in the local structural environment of particles that will be part of plastic rearrangements during the next shear cycle and that of particles that are immobile. In particular, particles with higher S 2 and lower n tet are more likely to go through rearrangements irrespective of the average energies of the configurations and strain amplitude. For high shear, we find very distinctive local order outside the mobile shear band region, where almost 30% of the particles are involved in icosahedral clusters, contrasting strongly with the fraction of < 5% found inside the shear band.

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Scaling of relaxation and excess entropy in plastically deformed amorphous solids

Cited by 21 publications

References 55 publications

Mechanical annealing and memories in a disordered solid

Mechanical annealing and memories in a disordered solid

Mechanical annealing and memories in a disordered solid

Correlation between plastic rearrangements and local structure in a cyclically driven glass

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