Dielectric Relaxation and Calorimetric Measurements of Glass    Transition in the Glass-Forming Dyhydroxyl Alcohols

The present work aims to provide insights on recent findings indicating the presence of multiple equilibration mechanisms in physical aging of glasses. To this aim, we have investigated a glass forming polyether, poly(1-4 cyclohexane di-methanol) (PCDM), by following the evolution of the enthalpic state during physical aging by fast scanning calorimetry (FSC). The main results of our study indicate that physical aging persists at temperatures way below the glass transition temperature and, in a narrow temperature range, is characterized by a two steps evolution of the enthalpic state. Altogether, our results indicate that the simple old-standing view of physical aging as triggered by the α relaxation does not hold true when aging is carried out deep in the glassy state.

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Glass Formation and Glass Forming Ability of Alloys Near Eutectic Composition

MRS Proceedings ◽

10.1557/proc-644-l3.4 ◽

2000 ◽

Vol 644 ◽

Cited By ~ 1

Author(s):

Y. Li

Keyword(s):

Glass Transition ◽

Glass Formation ◽

Eutectic Composition ◽

Glass Forming Ability ◽

Critical Section ◽

Bulk Glass ◽

Melting Behaviour ◽

Eutectic Alloys ◽

Section Thickness ◽

Glass Forming

AbstractOnset temperature, Tm and offset temperature (liquidus) Tl of melting of a series of bulk glass forming alloys based on La, Mg, and Pd have been measured by studying systematically the melting behaviour of these alloys using DTA or DSC. Bulk metallic glass formation has been found to be most effective at or near their eutectic points and less effective for off-eutectic alloys. Reduced glass transition temperature Trg given by Tg/Tl is found to show a stronger correlation with critical cooling rate or critical section thickness for glass formation than Trg given by Tg/Tm.

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Dynamics of glass-forming liquids. XVII. Dielectric relaxation and intermolecular association in a series of isomeric octyl alcohols

The Journal of Chemical Physics ◽

10.1063/1.4823998 ◽

2013 ◽

Vol 139 (14) ◽

pp. 144503 ◽

Cited By ~ 38

Author(s):

Lokendra P. Singh ◽

Christiane Alba-Simionesco ◽

Ranko Richert

Keyword(s):

Dielectric Relaxation ◽

Glass Forming ◽

Intermolecular Association

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Strong Liquid Behavior of Zr-Ti-Cu-Ni-Be Bulk Metallic Glass Forming Alloys

MRS Proceedings ◽

10.1557/proc-455-369 ◽

1996 ◽

Vol 455 ◽

Cited By ~ 26

Author(s):

Ralf Busch ◽

Andreas Masuhr ◽

Eric Bakke ◽

William L. Johnson

Keyword(s):

Glass Transition ◽

Melting Point ◽

Metallic Glass ◽

Bulk Metallic Glass ◽

Supercooled Liquid ◽

Glass Transition Region ◽

Glass Forming ◽

Liquid Behavior ◽

Metallic Liquids ◽

Microscopic Origin

ABSTRACTThe viscosities of the Zr46.75Ti8.25Cu7.5Ni10Be27.5 and the Zr41.2Ti13.8Cu12.5Ni10Be22.5 bulk metallic glass forming liquids was determined from the melting point down to the glass transition in the entire temperature range of the supercooled liquid. The temperature dependence of the viscosity in the supercooled liquid obeys the Vogel-Fulcher-Tammann (VFT) relation. The fragility index D is about 20 for both alloys and the ratio between glass transition temperature and VFT temperature is found to be 1.5. A comparison with other glass forming systems shows that these bulk metallic glass formers are strong liquids comparable to sodium silicate glass. Furthermore, they are the strongest among metallic glass forming liquids. This behavior is a main contributing factor to the glass forming ability since it implicates a higher viscosity from the melting point down to the glass transition compared to other metallic liquids. Thus, the kinetics in the supercooled liquid is sluggish and yields a low critical cooling rate for glass formation. The relaxation behavior in the glass transition region of the alloys is consistent with their strong glassy nature as reflected by a stretching exponent that is close to 0.8. The microscopic origin of the strong liquid behavior of bulk metallic glass formers is discussed.

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Using Dielectric Relaxation Spectroscopy to Characterize the Glass Transition and Onset of Crystallinity of Skim-Milk Powder

10.20944/preprints201804.0105.v1 ◽

2018 ◽

Author(s):

Martin G. Buehler

Keyword(s):

Glass Transition ◽

Shelf Life ◽

Dielectric Relaxation ◽

Loss Tangent ◽

Milk Powder ◽

Skim Milk ◽

Skim Milk Powder ◽

Dielectric Relaxation Spectroscopy ◽

Scanning Calorimetry ◽

Boundary Curves

This paper describes the dielectric relaxation spectroscopy (DRS) method for obtaining glass transition temperature and the onset of crystallinity of skim milk powder (SMP). The methodology consists of exposing SMP samples to numerous constant temperatures, T, and water activities, aw, and measuring the relaxation time. Measurements are based on changes in the loss-tangent height at its peak frequency. Glass transition times are identified at peaks in the loss-tangent height versus time curve and the onset of crystallinity times are identified when the loss-tangent height collapses. The analysis leads to two boundary curves: glass transition Tg, aw curve and the onset of crystallinity Tc, aw curve. They separate the SMP stable (long shelf life) and unstable (short shelf life) regions. Two curve fitting algorithms were developed for (a) aw2, tg curve where tg is the time to glass transition and aw2, tc curve where time tc is the time to onset of crystallinity and (b) Tg, aw and Tc, aw boundary curves. Finally, the DRS data are compared to differential scanning calorimetry (DSC) results.

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Experimental Study of the Liquid-Glass Transition in an Inorganic Polymer Li0.5Na0.5PO3

MRS Proceedings ◽

10.1557/proc-407-155 ◽

1995 ◽

Vol 407 ◽

Cited By ~ 1

Author(s):

B. Rufflé ◽

S. Beaufils ◽

Y. Délugeard ◽

G. Coddens ◽

J. Etrillard ◽

...

Keyword(s):

Experimental Study ◽

Glass Transition ◽

Raman Scattering ◽

Viscous Flow ◽

Liquid Glass ◽

Low Frequency ◽

Glass Forming ◽

Scattering Spectra ◽

Temperature Ranges ◽

Raman Scattering Spectra

ABSTRACTNew experimental results obtained with various techniques on a less-studied glass-forming system are presented. At low frequency, a secondary βslow-process, decoupled from the viscous flow, is observed by 3 1P NMR. Raman scattering spectra and coherent neutron scattering spectra has been obtained in wide frequency and temperature ranges showing the same qualitative features for the Boson peak while the quasielastic contribution seems to differ markedly.

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Comments on “Fabrication of ternary Mg–Cu–Gd bulk metallic glass with high glass-forming ability under air atmosphere” [H. Men and D.H. Kim, J. Mater. Res. 18, 1502 (2003)]

Journal of Materials Research ◽

10.1557/jmr.2004.19.2.427 ◽

2004 ◽

Vol 19 (2) ◽

pp. 427-428 ◽

Cited By ~ 2

Author(s):

Z.P. Lu ◽

C.T. Liu

Keyword(s):

Glass Transition ◽

Metallic Glasses ◽

Supercooled Liquid ◽

Supercooled Liquid Region ◽

Glass Forming Ability ◽

Bulk Amorphous Alloy ◽

Liquid Region ◽

Glass Forming ◽

Air Atmosphere ◽

Acta Mater

A new Mg-based bulk amorphous alloy (i.e., Mg65Cu25Gd10) has successfully been developed by Men and Kim [H. Men and D.H. Kim, J. Mater. Res. 18, 1502 (2003)]. They showed that this alloy exhibits significantly improved glass-forming ability (GFA) in comparison with Mg65Cu25Y10 alloy. However, this improved GFA cannot be indicated by the supercooled liquid region ΔT and the reduced glass-transition temperature Trg. As shown in the current comment, the new parameter γ, Tx/(Tg + Tl) defined in our recent papers [Z.P. Lu and C.T. Liu, Acta Mater. 50, 3501 (2002); Z.P. Lu and C.T. Liu, Phys. Rev. Lett. 91, 115505 (2003)] can well gauge GFA for bulk metallic glasses, including the current Mg-based alloys.

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