Structural relaxation and viscous flow in amorphous ZrAlCu

Rambousky, Ronald; Moske, M.; Samwer, K.

doi:10.1007/bf02769958

Cited by 14 publications

(18 citation statements)

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“…On the contrary, there does exist a strong precedent for the use of stretched exponentials to describe relaxation in disordered condensed matter physics. In fact both polymer networks 38 and glasses near their transition temperature 35,36 relax according to stretch exponentials. Notably, such glassy polymer response has already been linked to the mechanical behavior of the cytoskeleton 39 .…”

Section: Discussionmentioning

confidence: 99%

“…Although we have not come across previous reports that have modeled the viscoelastic behavior of cells or tissues with stretched exponentials, they have been widely used to describe relaxation in glassy, disordered systems that display a broad distribution of timescales 35,36 . In regards to microtissues, however, a stretched exponential captured both stress relaxation and recovery data over three decades of time (R 2 >0.99) with average fitting constants summarized in table 1.…”

Section: Microtissues Are Viscoelasticmentioning

confidence: 99%

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Time dependent stress relaxation and recovery in mechanically strained 3D microtissues

Walker

Godin

Harden

et al. 2020

Preprint

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Characterizing the elastic and dissipative properties of cells is not only necessary to determine how they deform, but also to fully understand how external mechanical forces trigger biochemical--signaling cascades to govern their behavior. Presently mechanical properties are largely assessed by applying local shear or compressive forces on single cells in isolation grown on non--physiological 2D surfaces. In comparison, our microfabricated vacuum actuated stretcher measures tensile loading of 3D multicellular 'microtissue' cultures. With our approach, we assessed here the time--dependency of microtissue mechanics and quantified the spatial remodeling that follows step length changes. Unlike previous results from other micro--rheological techniques, stress relaxation and recovery in microtissues followed stretched exponential behaviors that shared similar amplitudes but differed in their dynamics. In that regard, relaxation time constants changed with an inverse power law with step size, while recovery rates were invariant. Pharmacological responses, however, indicated that the contributions of individual cytoskeletal elements did not qualitatively differ from our existing understanding of their roles. The elasticity and dissipation of microtissues were mainly determined by the actin cytoskeleton but also augmented by myosin motor activity and reduced by the presence of microtubules. These results were reflected in changes to remodeling dynamics and spatial distributions of the integrated strain field. This assessment of microtissues offers insights into how the collective behavior of cells and their cytoskeletal proteins generate the dynamic mechanical properties of tissues, which is necessary for a full understanding of how cell behaviors are regulated in both health and disease.

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Section: Discussionmentioning

confidence: 99%

Section: Microtissues Are Viscoelasticmentioning

confidence: 99%

Time dependent stress relaxation and recovery in mechanically strained 3D microtissues

Walker

Godin

Harden

et al. 2020

Preprint

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“…Nevertheless, the basic understanding of the glass transition is still a matter of debate [4]. In recent years a number of viscosity [5,6], anelastic relaxation [7], thermal expansion [8][9][10], and specific heat capacity measurements [11,12] have been performed on the new multicomponent metallic systems. The results confirm the so-called "strong" nature of the glass forming liquid, which exhibits high melt viscosities and Kohlrausch-Watts-Williams exponents around 0.66 near T g .…”

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confidence: 99%

Change of Compressiblity at the Glass Transition and Prigogine-Defay Ratio in ZrTiCuNiBe Alloys

1999

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The change of the compressibility at the glass transition T g is evaluated from pressure experiments in the liquid and the glassy state of the ZrTiCuNiBe bulk metallic glass forming system. Via the enthalpy recovery method, we derive an increase of T g with pressure of 3.6 K͞GPa. Comparing the changes of the compressibility, the specific heat capacity, and the thermal expansion coefficient at T g , we estimate for the first time a Prigogine-Defay ratio in metallic systems. This ratio is about 2.4 for the present alloy and compares well with known nonmetallic glass forming systems. [S0031-9007(98) The development of multicomponent bulk metallic glass forming alloys [1,2] has opened the possibility to study the nature of the glass transition also in metallic systems. Glassy phases have been found in a variety of different systems such as polymers, silica, orientational glasses, spin glasses, etc. [3]. Nevertheless, the basic understanding of the glass transition is still a matter of debate [4]. In recent years a number of viscosity [5,6], anelastic relaxation [7], thermal expansion [8][9][10], and specific heat capacity measurements [11,12] have been performed on the new multicomponent metallic systems. The results confirm the so-called "strong" nature of the glass forming liquid, which exhibits high melt viscosities and Kohlrausch-Watts-Williams exponents around 0.66 near T g . Furthermore, they show a step of the specific heat and thermal expansion coefficient at T g . Knowing these second derivates of the Gibbs free energy, one can consider discussing Ehrenfest's relations and the Prigogine-Defray ratio for these materials also [13,14].In this Letter, we present measurements of the heat flow at the glass transition of Zr 46.25 Ti 8.25 Cu 7.5 Ni 10 Be 27.5 (Vit 4) alloys which have been processed at different hydrostatic pressures. Differential scanning calorimetry at a fixed rate is used to obtain the enthalpy of the as-quenched alloys as well as of samples that were annealed below T g at different pressures. Thereby, we can estimate the enthalpy change and the change in T g with applied hydrostatic pressure. Using this knowledge for the known temperature dependence of the specific volume, we also calculate the change in volume with pressure and get the change of the compressibility at the glass transition. From there it becomes possible to calculate the Prigogine-Defay ratio with the thermodynamic quantities specific heat, compressibility, and thermal expansion for the first time for metallic systems.The measurements were performed on Vit 4 bulk metallic glasses produced by cooling the alloy from the liquid into the glassy state in a quartz container. This particular alloy was chosen because no dramatic phase separation in the supercooled or amorphous phase has been observed here, in contrast to other alloys of the ZrTiCuNiBe family. The samples (10 mm in diameter and several cm long) were machined down into 6 mm diameter rods which fit the steel and tungsten carbide (WC) pressure cells used in a previous stud...

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“…3 At lower temperatures, the onset of the glass transition depends on the cooling rate 4 or the external frequency. 5 The viscosity of the material tends to follow a Vogel-Fulcher-Tammann ͑VFT͒ law upon cooling, 6 until the ␣-relaxation mode "freezes" at T g on experimental time scales of Ϸ100 s. The predicted divergence of the relaxation time at a finite VFT-temperature remains inconsequential, as has recently been demonstrated in a careful analysis of viscosity data. 7 In contrast, the slow ␤-or Johari-Goldstein mode is believed to be responsible for lowtemperature diffusion, 8 which is found to operate at temperatures as low as 200°C below T g .…”

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confidence: 89%

Dynamical and quasistatic structural relaxation paths in Pd40Ni40P20 glass

Kahl

Koeppe

Bedorf

et al. 2009

Applied Physics Letters

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By sequential heat treatment of a Pd 40 Ni 40 P 20 metallic glass at temperatures and durations for which ␣-relaxation is not possible, dynamic, and quasistatic relaxation paths below the glass transition are identified via ex situ ultrasonic measurements following each heat treatment. The dynamic relaxation paths are associated with hopping between nonequilibrium potential energy states of the glass, while the quasistatic relaxation path is associated with reversible ␤-relaxation events toward quasiequilibrium states. These quasiequilibrium states are identified with secondary potential energy minima that exist within the inherent energy minimum of the glass, thereby supporting the concept of the sub-basin/metabasin organization of the potential-energy landscape. © 2009 American Institute of Physics. ͓doi:10.1063/1.3266828͔In recent years, descriptions of the structural kinetic behavior of metallic liquids and glasses have been significantly revisited. 1 It became evident that various secondary structural relaxation modes instead of a single primary one are necessary to accurately describe the entire dynamic behavior of a metallic glass. 2 These secondary structural relaxation modes, termed Johari-Goldstein or slow ␤-modes, and the primary structural relaxation termed ␣-mode merge at a temperature above the glass transition specific for each material. This merging temperature is very close to the critical temperature of mode-coupling theory. 3 At lower temperatures, the onset of the glass transition depends on the cooling rate 4 or the external frequency. 5 The viscosity of the material tends to follow a Vogel-Fulcher-Tammann ͑VFT͒ law upon cooling, 6 until the ␣-relaxation mode "freezes" at T g on experimental time scales of Ϸ100 s. The predicted divergence of the relaxation time at a finite VFT-temperature remains inconsequential, as has recently been demonstrated in a careful analysis of viscosity data. 7 In contrast, the slow ␤-or Johari-Goldstein mode is believed to be responsible for lowtemperature diffusion, 8 which is found to operate at temperatures as low as 200°C below T g . 2 In the past, changes in Young's modulus, 9 decrease in free volume, 10 or irreversible effects in the diffusion mechanism in asquenched samples have been attributed to the ␤-relaxation mode in these alloys, 3 suggesting that aging is a cooperative phenomenon as described in many earlier molecular dynamics simulations. 11 In a recent paper, 12 these secondary ␤-relaxation events were identified with reversible anelastic excitations within the elastic matrix confinement, and an ␣-relaxation event was identified with the collapse of the matrix confinement and the breakdown of elasticity, a view consistent with Eshelby's concept of elastic confinement. 13 In a different approach Khonik et al. 14 showed very recently, that structural relaxation can change significantly the concentration of so called interstitiallylike defects leading also to a distinct change of the shear modulus depending on the quenched, annealed or initial condit...

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Structural relaxation and viscous flow in amorphous ZrAlCu

Cited by 14 publications

References 15 publications

Time dependent stress relaxation and recovery in mechanically strained 3D microtissues

Time dependent stress relaxation and recovery in mechanically strained 3D microtissues

Change of Compressiblity at the Glass Transition and Prigogine-Defay Ratio in ZrTiCuNiBe Alloys

Dynamical and quasistatic structural relaxation paths in Pd40Ni40P20 glass

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