Non-monotonic variations of the nucleation free energy in a glass-forming ultra-soft particles fluid

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-Forming Ability and Crystallization of High Purity Pd-Cu-Ni-P Alloy

MRS Proceedings ◽

10.1557/proc-644-l3.1 ◽

2000 ◽

Vol 644 ◽

Cited By ~ 1

Author(s):

Nobuyuki Nishiyama ◽

Mitsuhide Matsushita ◽

Akihisa Inoue

Keyword(s):

High Purity ◽

Isothermal Annealing ◽

Glass Forming Ability ◽

In Situ Tem ◽

Nucleation Behavior ◽

Spherical Region ◽

Glass Forming ◽

High Purity Alloy ◽

Nose Temperature

AbstractGlass-forming ability, thermal stability and nucleation behavior of a Pd40Cu30Ni10P20 alloy prepared using a high purity polycrystalline phosphorus are investigated. The critical cooling rate for glass formation for the high purity alloy is the same as that for the previous result, but the improvement of undercooling reaches about 80 K as compared with the fluxed ordinary alloy. In comparison with the non-fluxed alloy, the solidified structure of the present highly purified alloy is significantly different. The non-fluxed sample shows the characteristic “island-like” structure consisted of acicular fcc-Pd2Ni2P solid solution and Cu3Pd intermetallic compound. These acicular phases appear to be caused by the growth of quenched-in nuclei. In the isothermal experiment, nucleus density exhibits time dependence even at 683 K near the nose temperature. It is assumed that the crystallization behavior for the highly purified alloy is closer to homogeneous nucleation from quenched-in nuclei dominant behavior. In order to investigate the nucleation behavior, in-situ TEM observation was carried out. Spherical Pd15P2 particle with a diameter about 15 nm is observed, and this spherical region repeats generation and annihilation during isothermal annealing. The reason for the high glass-forming ability is discussed on the basis of the obtained results.

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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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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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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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Long-Term Physical (In)Stability of Spray-Dried Amorphous Drugs: Relationship with Glass-Forming Ability and Physicochemical Properties

Pharmaceutics ◽

10.3390/pharmaceutics11090425 ◽

2019 ◽

Vol 11 (9) ◽

pp. 425 ◽

Cited By ~ 4

Author(s):

Edueng ◽

Bergström ◽

Gråsjö ◽

Mahlin

Keyword(s):

Glass Transition ◽

Transition Temperature ◽

Glass Transition Temperature ◽

Physicochemical Properties ◽

Physical Stability ◽

Glass Forming Ability ◽

Melt Quenching ◽

Glass Forming ◽

Spray Dried

This study shows the importance of the chosen method for assessing the glass-forming ability (GFA) and glass stability (GS) of a drug compound. Traditionally, GFA and GS are established using in situ melt-quenching in a differential scanning calorimeter. In this study, we included 26 structurally diverse glass-forming drugs (i) to compare the GFA class when the model drugs were produced by spray-drying with that when melt-quenching was used, (ii) to investigate the long-term physical stability of the resulting amorphous solids, and (iii) to investigate the relationship between physicochemical properties and the GFA of spray-dried solids and their long-term physical stability. The spray-dried solids were exposed to dry (<5% RH) and humid (75% RH) conditions for six months at 25 °C. The crystallization of the spray-dried solids under these conditions was monitored using a combination of solid-state characterization techniques including differential scanning calorimetry, Raman spectroscopy, and powder X-ray diffraction. The GFA/GS class assignment for 85% of the model compounds was method-dependent, with significant differences between spray-drying and melt-quenching methods. The long-term physical stability under dry condition of the compounds was predictable from GFA/GS classification and glass transition and crystallization temperatures. However, the stability upon storage at 75% RH could not be predicted from the same data. There was no strong correlation between the physicochemical properties explored and the GFA class or long-term physical stability. However, there was a slight tendency for compounds with a relatively larger molecular weight, higher glass transition temperature, higher crystallization temperature, higher melting point and higher reduced glass transition temperature to have better GFA and better physical stability. In contrast, a high heat of fusion and entropy of fusion seemed to have a negative impact on the GFA and physical stability of our dataset.

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Observation of an apparent first-order glass transition in ultrafragile Pt–Cu–P bulk metallic glasses

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1916371117 ◽

2020 ◽

Vol 117 (6) ◽

pp. 2779-2787 ◽

Cited By ~ 2

Author(s):

Jong H. Na ◽

Sydney L. Corona ◽

Andrew Hoff ◽

William L. Johnson

Keyword(s):

Glass Transition ◽

Configurational Entropy ◽

Freezing Temperature ◽

Thin Wall ◽

First Order ◽

Cu Content ◽

Kauzmann Temperature ◽

Entropy Of Fusion ◽

Glass Forming ◽

Third Law Of Thermodynamics

An experimental study of the configurational thermodynamics for a series of near-eutectic Pt80-xCuxP20 bulk metallic glass-forming alloys is reported where 14 < x < 27. The undercooled liquid alloys exhibit very high fragility that increases as x decreases, resulting in an increasingly sharp glass transition. With decreasing x, the extrapolated Kauzmann temperature of the liquid, TK, becomes indistinguishable from the conventionally defined glass transition temperature, Tg. For x < 17, the observed liquid configurational enthalpy vs. T displays a marked discontinuous drop or latent heat at a well-defined freezing temperature, Tgm. The entropy drop for this first-order liquid/glass transition is approximately two-thirds of the entropy of fusion of the crystallized eutectic alloy. Below Tgm, the configurational entropy of the frozen glass continues to fall rapidly, approaching that of the crystallized eutectic solid in the low T limit. The so-called Kauzmann paradox, with negative liquid entropy (vs. the crystalline state), is averted and the liquid configurational entropy appears to comply with the third law of thermodynamics. Despite their ultrafragile character, the liquids at x = 14 and 16 are bulk glass formers, yielding fully glassy rods up to 2- and 3-mm diameter on water quenching in thin-wall silica tubes. The low Cu content alloys are definitive examples of glasses that exhibit first-order melting.

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