Relationship between the shear modulus<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>G</mml:mi></mml:math>, activation energy, and shear viscosity<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>η</mml:mi></mml:math>in metallic glasses below and above<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mi>T</mml:mi><mml:mi>g</mml:mi></mml:msub></mml:mrow></mml:math>: Direct<i>in situ</i>measure

Khonik, V. A.; Mitrofanov, Yu.P.; Lyakhov, S. A.; Vasiliev, A. N.; Khonik, S. V.; Khoviv, D. A.

doi:10.1103/physrevb.79.132204

Cited by 38 publications

(38 citation statements)

References 24 publications

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“…The understanding of the glass formation and the relation between the structure, the atomic motion and the unique properties of these remarkable materials is therefore not only fundamental from a theoretical point of view, but it is clearly unavoidable if one wants to use them for practical applications. Below Tg, MGs -like all glasses -are in an out of equilibrium state and their dynamical and elastic properties depend on the previous thermal history of the sample and will evolve with time [3][4][5][6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Structural and dynamical properties of Mg65Cu25Y10 metallic glasses studied by in situ high energy X-ray diffraction and time resolved X-ray photon correlation spectroscopy

Ruta

Giordano

Erra

et al. 2014

Journal of Alloys and Compounds

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We present a temperature investigation of the structural and dynamical evolution of rapidly quenched metallic glasses of Mg65Cu25Y10 at the atomic length scale by means of in situ high energy x-ray diffraction and time resolved x-ray photon correlation spectroscopy. We find a flattening of the temperature evolution of the position of the first sharp diffraction peak on approaching the glass transition temperature from the glassy state, which reflects into a surprising slowing down of the relaxation dynamics of even one order of magnitude with increasing temperature. The comparison between structural and dynamical properties strengthens the idea of a stress-induced, rather than pure diffusive, atomic motion in metallic glasses.

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Section: Introductionmentioning

confidence: 99%

Structural and dynamical properties of Mg65Cu25Y10 metallic glasses studied by in situ high energy X-ray diffraction and time resolved X-ray photon correlation spectroscopy

Ruta

Giordano

Erra

et al. 2014

Journal of Alloys and Compounds

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“…This extension is consistent with previous works by Khronik et al, who introduced the idea of a distribution of local shear moduli to explain sub T g relaxations within the shoving-model framework. 5,6 Commenting on the instantaneous shear modulus of the shoving model Puosi and Leporini wrote: "It is quite apparent that G ∞ , the central quantity of the standard elastic models, poorly correlates with the structural relaxation time." This conclusion derives from the understanding that the shoving model and related elastic models are based on the idealized affine infinite-frequency shear modulus, not the experimentally measurable high-frequency plateau modulus, which was traditionally used for comparing model to experiment.…”

Section: Introductionmentioning

confidence: 99%

The instantaneous shear modulus in the shoving model

Dyre

Wang

2012

The Journal of Chemical Physics

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Model for the alpha and beta shear-mechanical properties of supercooled liquids and its comparison to squalane data The Journal of Chemical Physics 146, 154504 (2017) We point out that the instantaneous shear modulus G ∞ of the shoving model for the non-Arrhenius temperature dependence of viscous liquids' relaxation time is the experimentally accessible highfrequency plateau modulus, not the idealized instantaneous affine shear modulus that cannot be measured. Data for a large selection of metallic glasses are compared to three different versions of the shoving model. The original shear-modulus based version shows a slight correlation to the Poisson ratio, which is eliminated by the energy-landscape formulation of the model in which the bulk modulus plays a minor role.

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“…Although aging is known since centuries, a clear picture of the dynamics in the glassy state is still missing [3,4]. Most of the experimental information available on aging concerns macroscopic quantities, such as viscosity or elastic moduli [5][6][7][8][9][10][11], or focuses on dielectric relaxation [12][13][14][15][16][17], a quantity that is often difficult to relate directly to the particle-level dynamics. From these measurements, a characteristic time for the evolution towards equilibrium can be extracted, but no direct information on the connection between aging and the underlying microscopic dynamics is available.…”

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confidence: 99%

Atomic-Scale Relaxation Dynamics and Aging in a Metallic Glass Probed by X-Ray Photon Correlation Spectroscopy

et al. 2012

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We use X-Ray Photon Correlation Spectroscopy to investigate the structural relaxation process in a metallic glass on the atomic length scale. We report evidence for a dynamical crossover between the supercooled liquid phase and the metastable glassy state, suggesting different origins of the relaxation process across the transition. Furthermore, using different cooling rates we observe a complex hierarchy of dynamic processes characterized by distinct aging regimes. Strong analogies with the aging dynamics of soft glassy materials, such as gels and concentrated colloidal suspensions, point at stress relaxation as a universal mechanism driving the relaxation dynamics of out-of-equilibrium systems.PACS numbers: 64.70.pe,65.60.+a,64.70.pv Glasses are usually defined as liquids that are trapped in a metastable state from which they slowly evolve toward the corresponding equilibrium phase [1,2]. Although aging is known since centuries, a clear picture of the dynamics in the glassy state is still missing [3,4]. Most of the experimental information available on aging concerns macroscopic quantities, such as viscosity or elastic moduli [5][6][7][8][9][10][11], or focuses on dielectric relaxation [12][13][14][15][16][17], a quantity that is often difficult to relate directly to the particle-level dynamics. From these measurements, a characteristic time for the evolution towards equilibrium can be extracted, but no direct information on the connection between aging and the underlying microscopic dynamics is available. By contrast, a full understanding of aging requires a detailed description of the particle-level dynamics, and in particular of the structural relaxation time τ , the characteristic time for a system to rearrange its structure on the length scale of its constituents. While the structural relaxation has been widely investigated in the liquid phase, only a few studies report on the behaviour of τ below the glass transition temperature, T g [14-16, 18]. Molecular dynamics simulations show that τ increases linearly or sub-linearly with the waiting time, t w , and suggest the possibility of rescaling the measured quantities on a single master curve (time-waiting time superposition principle) [18]. Studies in this direction, however, have led to debated results [5,12,13,17,19]. Consequently, several key questions remain unanswered: what is the fate of the structural relaxation process when the system falls out of equilibrium in the glassy state? How does it depend on the thermal history and the waiting time? What physical mechanism is responsible for structural relaxation? Here, we address these questions by presenting an experimental investigation of the structural relaxation on the atomic length scale in a metallic glass former, in both the supercooled liquid and the glassy state, as a function of temperature and waiting time, and for different thermal histories. We use X-Ray Photon Correlation Spectroscopy (XPCS) to study Mg 65 Cu 25 Y 10 , a well-known glass former with a relatively low T g ∼ 405 K and a st...

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Relationship between the shear modulusG, activation energy, and shear viscosityηin metallic glasses below and aboveTg: Directin situmeasure

Cited by 38 publications

References 24 publications

Structural and dynamical properties of Mg65Cu25Y10 metallic glasses studied by in situ high energy X-ray diffraction and time resolved X-ray photon correlation spectroscopy

Structural and dynamical properties of Mg65Cu25Y10 metallic glasses studied by in situ high energy X-ray diffraction and time resolved X-ray photon correlation spectroscopy

The instantaneous shear modulus in the shoving model

Atomic-Scale Relaxation Dynamics and Aging in a Metallic Glass Probed by X-Ray Photon Correlation Spectroscopy

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