Relaxation Processes Features of Glass-Forming Melts on the Basis of Copper

2015 ◽  
Vol 660 ◽  
pp. 108-112
Author(s):  
Viktor Konashkov ◽  
Vladimir Tsepelev ◽  
Arkadi Povodator
Keyword(s):  
Relaxation Process ◽  
Constant Temperature ◽  
Liquid State ◽  
Kinematic Viscosity ◽  
Relaxation Processes ◽  
Temperature Instability ◽  
State Data ◽  
Glass Forming ◽  
Heating And Cooling ◽  
Two Samples

Two samples of industrial alloys on the basis of copper are experimentally studied. These alloys are used for production of amorphous solders. The main studied property is kinematic viscosity of metal melt in a liquid state. Data of viscosity dependences from temperature when heating and the subsequent cooling are obtained. Besides, viscosity dependences at constant temperatures from time are received. On viscosity dependences from temperature, for the same samples, abnormal sites and a divergence of curves of heating and cooling are found. On viscosity dependences from time, at a constant temperature, instability is found. The conclusion is drawn that the revealed features are connected with complexity of relaxation process of the studied fusions.

Relaxation Phenomena and Thermodynamics of Liquids at Very High Pressures

1996 ◽  
Vol 464 ◽  
Author(s):  
W. F. Oliver
Keyword(s):  
High Pressure ◽  
Glass Transition ◽  
Light Scattering ◽  
Liquid State ◽  
High Pressures ◽  
Equations Of State ◽  
Brillouin Scattering ◽  
Dynamic Properties ◽  
Relaxation Processes ◽  
Glass Forming

ABSTRACTComplex liquid glass-forming systems ranging from those composed of simple molecules to polymer melts and amorphous polymers have been studied extensively as a function of temperature resulting in a basic understanding of liquid-state dynamics and glass transition phenomenology as these systems are supercooled to the vitreous state. An important aspect of this problem that remains largely unexplored, and that is relevant to the topic of this symposium, involves liquid-state dynamics and vitrification (as well as crystallization) in the regime of high pressure and high density. We describe work on “fragile” to “intermediate strength” simple organic glass-forming liquids where both temperature (T) and pressure (P) are varied. Diamond anvil cells are used to achieve pressures exceeding 10 GPa. Several optical and light scattering techniques are used to explore both static and dynamic properties of these systems. High-pressure Brillouin scattering enables us to model the longitudinal relaxation time in these systems as well as their equations of state. These can now be refined by direct measurements of the pressure dependence of the glass transition, Tg(P). Finally, we summarize depolarized light scattering studies which allow us to compare both the isobaric and isothermal evolution of structural (α) and fast (β) relaxation processes.

Dynamic structure factors due to relaxation processes in glass-forming polymers

1997 ◽  
Vol 241-243 ◽  
pp. 1005-1012 ◽  
Author(s):  
D. Richter ◽  
M. Monkenbusch ◽  
A. Arbe ◽  
J. Colmenero ◽  
B. Farago
Keyword(s):  
Dynamic Structure ◽  
Relaxation Processes ◽  
Glass Forming ◽  
Structure Factors

scholarly journals Calorimetric glass transition in a mean-field theory approach

2015 ◽  
Vol 112 (8) ◽  
pp. 2361-2366 ◽  
Author(s):  
Manuel Sebastian Mariani ◽  
Giorgio Parisi ◽  
Corrado Rainone
Keyword(s):  
Mean Field Theory ◽  
Mean Field ◽  
Supercooled Liquid ◽  
Analytic Solutions ◽  
Theory Approach ◽  
Mean Field Model ◽  
Thermalization Time ◽  
Glass Forming ◽  
Heating And Cooling ◽  
Spatial Dimensions

The study of the properties of glass-forming liquids is difficult for many reasons. Analytic solutions of mean-field models are usually available only for systems embedded in a space with an unphysically high number of spatial dimensions; on the experimental and numerical side, the study of the properties of metastable glassy states requires thermalizing the system in the supercooled liquid phase, where the thermalization time may be extremely large. We consider here a hard-sphere mean-field model that is solvable in any number of spatial dimensions; moreover, we easily obtain thermalized configurations even in the glass phase. We study the 3D version of this model and we perform Monte Carlo simulations that mimic heating and cooling experiments performed on ultrastable glasses. The numerical findings are in good agreement with the analytical results and qualitatively capture the features of ultrastable glasses observed in experiments.

scholarly journals Effect of Temperature and Used Ingredients on Rheological Parameters of Pancake Dough

2013 ◽  
Vol 16 (3) ◽  
pp. 63-66
Author(s):  
Peter Hlaváč ◽  
Monika Božiková
Keyword(s):  
Rheological Properties ◽  
Dynamic Viscosity ◽  
Kinematic Viscosity ◽  
Fat Content ◽  
Effect Of Temperature ◽  
Rheological Parameters ◽  
Rotational Viscometer ◽  
Two Samples ◽  
Dynamic And Kinematic Viscosity ◽  
Temperature Dynamic

Abstract This paper presents the selected rheological properties of pancake dough such as dynamic and kinematic viscosity and fluidity. The effect of used ingredients and temperature on rheological properties is investigated. Measurements were performed on three pancake dough samples. In two samples, there was used milk with a different fat content, and in the third sample, all ingredients were in a powder state. A digital rotational viscometer Anton Paar DV-3P was used for measuring the rheological properties. The principle of viscometer measurement is based on the dependence of sample resistance to probe rotation. Results of measurements are shown as graphical dependencies of rheological parameters on temperature. Exponential functions were used to express the dependencies of all rheological parameters on temperature. Dynamic and kinematic viscosity decreased, and fluidity increased with temperature. The highest values of dynamic viscosity were obtained for pancake dough from powder ingredients. A higher fat content of used milk caused higher values of dynamic viscosity.

scholarly journals The Dynamic Properties of 5Cb Filled with Aerosil Particles Investigated by Pcs

1999 ◽  
Vol 559 ◽  
Author(s):  
F.M. Aliev ◽  
M. Kreuzer ◽  
Yu.P. Panarin
Keyword(s):  
Liquid Crystal ◽  
Temperature Dependence ◽  
Relaxation Process ◽  
Nematic Liquid Crystal ◽  
Broad Spectrum ◽  
Dynamic Properties ◽  
Relaxation Times ◽  
Correlation Spectroscopy ◽  
Relaxation Processes ◽  
Optoelectronic Application

ABSTRACTNematic liquid crystal filled with Aerosil particles, a prospective composite material for optoelectronic application, has been investigated by static light scattering and Photon Correlation Spectroscopy (PCS). The Aerosil particles in filled nematic liquid crystals (FN) form a network structure with LC domains about 2500 Å in size with a random distribution of the director orientation of each domain.We found that the properties of 5CB are considerably affected by the network. The N-I phase transition in filled 5CB was found to be smeared out and depressed. PCS experiments show that two new relaxation processes appear in filled 5CB in addition to the director fluctuation process in bulk. The slow relaxation process, with a broad spectrum of relaxation times, is somewhat similar to the slow decay, which is observed in confined nematic liquid crystal.The middle frequency process was assigned to the director fluctuations in the surface layer formed at the particle-LC interface. The decay function describing this relaxation process is a stretched exponential (β ≍ 0.7). The temperature dependence of the relaxation times of the middle frequency obeys the Vogel-Rilcher law. Such a temperature dependence, accompanied by a broad spectrum of relaxation times suggests that the dynamics of the director fluctuations near the Aerosil particle-LC interface is glass-like.

Structural Relaxation Process in CuHfTi Amorphous Alloys

2009 ◽  
Vol 283-286 ◽  
pp. 533-538 ◽  
Author(s):  
Kazumasa Yamada ◽  
N. Shinagawa ◽  
M. Sogame ◽  
I.A. Figueroa ◽  
Hywel A. Davies ◽  
...  
Keyword(s):  
Activation Energy ◽  
Relaxation Process ◽  
Structural Relaxation ◽  
Amorphous Alloys ◽  
Melt Spinning ◽  
Amorphous Materials ◽  
Ternary Alloys ◽  
Relaxation Processes ◽  
Scanning Calorimetry ◽  
Structure Relaxation

The aim of this research is to clarify a quantitative evaluation in the structural relaxation processes focusing on the activation energy in Cu based amorphous alloys. The activation energy for structural relaxation process in a metal type amorphous CuHfTi ternary alloys, with cross sections of typically 0.03 mm x 2.0 mm, prepared by chill-block melt spinning has been investigated by Differential Scanning Calorimetry (DSC) with a cyclically heating technique. Activation energies for structural relaxation with a spatial quantity in amorphous materials have been discussed by use of a relaxed ratio function that depends on annealing temperature and time. In the present work, the distributions for the Activation Energy Spectrum (AES) were observed almost 152 kJmol-1 (1.58 eV). Another result has been also established that the “reversible” AES model energy distribution though the cyclically structure relaxation occurs even in amorphous Cu60Hf20Ti20 alloy.

scholarly journals A microscopic look at the Johari-Goldstein relaxation in a hydrogen-bonded glass-former

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
F. Caporaletti ◽  
S. Capaccioli ◽  
S. Valenti ◽  
M. Mikolasek ◽  
A. I. Chumakov ◽  
...  
Keyword(s):  
Time Domain ◽  
Glassy State ◽  
Center Of Mass ◽  
Relaxation Processes ◽  
Undercooled Liquid ◽  
Microscopic Scale ◽  
Glass Forming ◽  
Full Explanation ◽  
Molecular Scale ◽  
Hydrogen Bonded

Abstract Understanding the glass transition requires getting the picture of the dynamical processes that intervene in it. Glass-forming liquids show a characteristic decoupling of relaxation processes when they are cooled down towards the glassy state. The faster (βJG) process is still under scrutiny, and its full explanation necessitates information at the microscopic scale. To this aim, nuclear γ-resonance time-domain interferometry (TDI) has been utilized to investigate 5-methyl-2-hexanol, a hydrogen-bonded liquid with a pronounced βJG process as measured by dielectric spectroscopy. TDI probes in fact the center-of-mass, molecular dynamics at scattering-vectors corresponding to both inter- and intra-molecular distances. Our measurements demonstrate that, in the undercooled liquid phase, the βJG relaxation can be visualized as a spatially-restricted rearrangement of molecules within the cage of their closest neighbours accompanied by larger excursions which reach out at least the inter-molecular scale and are related to cage-breaking events. In-cage rattling and cage-breaking processes therefore coexist in the βJG relaxation.

Experimental determination of the kinematic viscosity of glycerol-water mixtures

1994 ◽  
Vol 444 (1922) ◽  
pp. 573-581 ◽  
Keyword(s):  
Experimental Determination ◽  
Liquid State ◽  
Mass Fraction ◽  
Kinematic Viscosity ◽  
Limited Data ◽  
Glycerol Water ◽  
Mass Fractions ◽  
Comparative Accuracy ◽  
Water Glycerol

We have measured the kinematic viscosity of glycerol-water mixtures, for glycerol mass fractions ranging from 0 to 1, in the temperature range 10-50 °C. The measurements were made by using a series of Ubbelohde viscometers. Apart from comprehensiveness and comparative accuracy the present measurements expose serious errors in the limited data that were earlier available on such mixtures. It is shown that all the data can be reasonably represented by the empirical correlation (In ν m - In ν w )/(In ν g - In ν w ) = x g [1 + (1 - x g ) { a + bx g + cx g 2 }], where ν w , v g and ν m are the kinematic viscosities of water, glycerol and the mixture respectively and x g is the mass fraction of glycerol in the mixture. The constants a, b and c are tabulated in the paper as functions of temperature. This correlation can now be used at a given temperature to tailor make a mixture of prescribed kinematic viscosity. While this paper is addressed, principally, to fluid dynamicists these results should be of interest to physicists studying the liquid state and physical chemists interested in mixtures.

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