Interrelation between shear modulus and the molecular parameters of viscous flow for glass forming liquids

Nemilov, S. V.

doi:10.1016/j.jnoncrysol.2006.04.001

Cited by 80 publications

(70 citation statements)

References 34 publications

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“…When the solid-liquid (S-L) transformation has been completed, the dynamic modulus of the melt slowly decreases with temperature and its evolution is consistent with theoretical models for ideal monoatomic liquid metals, based on the assumption of spatial isotropy and two-body central interaction [28,29].…”

Section: Resultssupporting

confidence: 71%

Synergic Role of Self-Interstitials and Vacancies in Indium Melting

Montanari

Varone

2015

Metals

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Precursor effects of indium melting have been investigated by means of Mechanical Spectroscopy (MS) and High Temperature X-ray Diffraction (HT-XRD). MS tests evidenced a sharp drop of dynamic modulus in the temperature range between 418 K and 429 K (melting point). At 429 K, HT-XRD showed partial grain re-orientation, peak profile broadening, in particular in the lower part, and peak shift towards lower angles. Experimental results are consistent with density increase of self-interstitials and vacancies in the crystal lattice before melting. Self-interstitials and vacancies play a synergic role in the solid-liquid (S-L) transformation. The increase of self-interstitials over a temperature range of about 10 K before melting has the effect of weakening interatomic bonds (modulus drop) that favors the successive vacancy formation. Finally, the huge increase of vacancy concentration above 428 K leads to the collapse of crystal lattice (melting).

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Section: Resultssupporting

confidence: 71%

Synergic Role of Self-Interstitials and Vacancies in Indium Melting

Montanari

Varone

2015

Metals

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“…This kind of peak shift is expected in the elastic models 17,18 , which postulate a proportionality between the barrier heights and the infinite frequency shear modulus G ∞ . What does not fit is the temperatureindependent curvature γ 2 , which should increase with T 2 /G 2 ∞ with increasing temperature.…”

Section: Comparison To Experimentssupporting

confidence: 52%

On the mechanism of the highly viscous flow

Buchenau

2011

The Journal of Chemical Physics

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The asymmetry model for the highly viscous flow postulates thermally activated jumps from a practically undistorted ground state to strongly distorted, but stable structures, with a pronounced Eshelby backstress from the distorted surroundings. The viscosity is ascribed to those stable distorted structures which do not jump back, but relax by the relaxation of the surrounding viscoelastic matrix. It is shown that this mechanism implies a description in terms of the shear compliance, with a viscosity which can be calculated from the cutoff of the retardation spectrum. Consistency requires that this cutoff lies close to the Maxwell time. The improved asymmetry model compares well with experiment.

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“…The shear modulus within the framework under consideration is the key thermodynamic parameter (as being the second derivative of the free energy with respect to the shear strain [53]) of glass, and precise measurements of G provide an efficient way to monitor the defect concentration and related relaxation kinetics. It is worthy of notice in this connection that the general idea for the key role of the shear modulus in the relaxation kinetics of supercooled liquids and glasses was introduced long ago [54] and currently is gaining increasing acceptance [55][56][57][58][59].…”

Section: Relaxation Kineticsmentioning

confidence: 99%

Understanding of the Structural Relaxation of Metallic Glasses within the Framework of the Interstitialcy Theory

Khonik

2015

Metals

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A review of the new approach to the understanding of the structural relaxation of metallic glasses based on the Interstitialcy theory has been presented. The key hypothesis of this theory proposed by Granato consists of the statement that the thermodynamic properties of crystalline, liquid and glassy states are closely related to the interstitial defects in the dumbbell (split) configuration, called also interstitialcies. It has been argued that structural relaxation of metallic glasses takes place through a change of the concentration of interstitialcy defects frozen-in from the melt upon glass production. Because of a strong interstitialcy-induced shear softening, the defect concentration can be precisely monitored by measurements of the unrelaxed shear modulus. Depending on the relation between the current interstitialcy concentration c and interstitialcy concentration in the metastable equilibrium, different types of structural relaxation (decreasing or increasing c) can be observed. It has been shown that this approach leads to a correct description of the relaxation kinetics at different testing conditions, heat effects occurring upon annealing, shear softening and a number of other structural relaxation-induced phenomena in metallic glasses. An intrinsic relation of these phenomena with the anharmonicity of the interatomic interaction has been outlined. A generalized form of the interstitialcy approach has been reviewed.

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Interrelation between shear modulus and the molecular parameters of viscous flow for glass forming liquids

Cited by 80 publications

References 34 publications

Synergic Role of Self-Interstitials and Vacancies in Indium Melting

Synergic Role of Self-Interstitials and Vacancies in Indium Melting

On the mechanism of the highly viscous flow

Understanding of the Structural Relaxation of Metallic Glasses within the Framework of the Interstitialcy Theory

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