Fractional Exponent of the Modified Stokes-Einstein Relation in the Metallic Glass-Forming Melt Pd43Cu27Ni10P20

2010 ◽  
Vol 146-147 ◽  
pp. 1463-1468
Author(s):  
Masahiro Ikeda ◽  
Masaru Aniya
Keyword(s):  
Diffusion Coefficient ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Metallic Glass ◽  
Bond Strength ◽  
Coordination Number ◽  
Einstein Relation ◽  
Glass Forming ◽  
Highly Correlated

The diffusion coefficient in the metallic glass-forming systems such as Pd-Cu-Ni-P exhibits a marked deviation from the Stokes-Einstein (SE) relation in the proximity of the glass transition temperature. Such a deviation is characterized by the fractional exponent p of the modified SE expression. For the material Pd43Cu27Ni10P20, it has been reported that it takes the value p = 0.75. In this work, it is shown that the value of p is highly correlated with the ratio ED / ENB, where ED and ENB are the activation energies for diffusion coefficient D and cooperativity NB defined by the Bond Strength-Coordination Number Fluctuation (BSCNF) model. The present paper reports that for the metallic glass-forming melt Pd43Cu27Ni10P20, the fractional exponent p can be calculated accurately within the framework of the BSCNF model.

Properties and Structure of BaO-ZnO-B2O3 Glasses

2008 ◽  
Vol 368-372 ◽  
pp. 1433-1435 ◽  
Author(s):  
Young Seok Kim ◽  
Young Joon Jung ◽  
Kyu Ho Lee ◽  
Tae Ho Kim ◽  
Bong Ki Ryu
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Coordination Number ◽  
Softening Temperature ◽  
Chemical Durability ◽  
The Other ◽  
Glass Forming ◽  
Other Hand ◽  
Glass Properties

The effect of coordination number on glass properties was investigated by measuring the glass forming region, glass transition temperature, dilatometric softening temperature, density and chemical durability of the glasses. The coordination number of B and Zn in the system 20BaO-xZnO-(80-x) B2O3 glasses (x=0~40mol%) was measured by IR, respectively. No change in the coordination number (CN) of B was revealed, and the coordination of Zn was 4 at ZnO 10mol%, which increased the properties of glasses. On the other hand, the coordination number (CN) of B and Zn changed from CN4 to CN3, CN4 to CN6 over ZnO 20 and 10mol% respectively, which decreased the properties of glasses.

A new Mg65Cu7.5Ni7.5Zn5Ag5Y10 bulk metallic glass with strong glass-forming ability

2003 ◽  
Vol 18 (10) ◽  
pp. 2288-2291 ◽  
Author(s):  
H. Ma ◽  
E. Ma ◽  
J. Xu
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Glass Forming Ability ◽  
Copper Mold ◽  
Glass Forming ◽  
Copper Mold Casting ◽  
Mold Casting

We report a new Mg-based bulk metallic glass-forming alloy: Mg65Cu7.5Ni7.5Zn5 Ag5Y10. The alloy exhibits a glass-forming ability significantly stronger than all previously discovered Mg-based glass formers. Fully glassy rods 9 mm in diameter can be obtained by using copper mold casting. The critical cooling rate for glass formation was estimated to be <50 Ks−1. The reduced glass-transition temperature (Trg) of the glass was determined to be 0.59.

Rare Earth Elements on Glass-Forming Ability and Thermal Stability of Cu-Zr-Al Metallic Glass

2011 ◽  
Vol 688 ◽  
pp. 426-430 ◽  
Author(s):  
Yan Fang Wang ◽  
Li Li ◽  
Chuan Sun ◽  
Qing Long Lu ◽  
Zhi Qiang Shi
Keyword(s):  
Thermal Stability ◽  
Glass Transition ◽  
Rare Earth ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Metallic Glass ◽  
Rare Earth Elements ◽  
Glass Forming Ability ◽  
Glass Forming ◽  
Thermal Stability Of

The rare earth elements (RE= Y, Sm, La, Ce) were used as alloying materials in Cu50Zr45Al5BMG, and their influences on the glass-forming ability and thermal stability were studied in this paper. All the samples remained in full metallic glass state with minor additions of Y, Sm and La. Increasing the amount of RE additions, the Cu10Zr7and Zr2Cu phases precipitated and glass transition temperatureTgand crystallization temperatureTxsignificantly decreased. The reduced glass transition temperature Trg=Tg/Tlranged from 0.592 to 0.611 and the γ parameter ranged from 0.393 to 0.409.

Effect of high pressure on glass transition in Zr-Ti-Cu-Ni-Be bulk metallic glass

2002 ◽  
Vol 754 ◽  
Author(s):  
Wei Hua Wang ◽  
Ping Wen ◽  
Yan Hui Zhao ◽  
Ming Xiang Pan ◽  
De Qian Zhao
Keyword(s):  
High Pressure ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Free Volume ◽  
Bulk Glass ◽  
Free Volume Theory ◽  
Glass Forming

ABSTRACTA new method is developed to directly exhibit glass transition in Zr-Ti-Cu-Ni-Be bulk glass-forming alloy under high pressure in metallic glass. Via the method, we derive an increase of glass transition temperature, Tg with pressure of 5.6 K/GPa, and a formation volume (ΔVf) of 6.5 Å3 for diffusion and the migration volume (ΔVm) of 6.5 Å3. The glass transition under high pressure is simulated based on the free-volume theory, and the simulations are consistent with the experimental observations.

Thermodynamic and kinetic fragilities of Mg-based bulk metallic glass-forming liquids

2008 ◽  
Vol 23 (10) ◽  
pp. 2816-2820 ◽  
Author(s):  
H. Ma ◽  
H-J. Fecht
Keyword(s):  
Relaxation Time ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Metallic Glass ◽  
Temperature Dependence ◽  
Bulk Metallic Glass ◽  
Excess Entropy ◽  
Gibbs Equation ◽  
Glass Forming

The thermodynamic and kinetic fragilities of two near-eutectic Mg-based bulk metallic glass (BMG)-forming liquids, Mg61Cu28Gd11 and Mg59.5Cu22.9Ag6.6Gd11, were investigated using high-precision differential scanning calorimeter (DSC). The thermodynamic fragility denoted as F3/4 was determined by evaluating the temperature dependence of the excess entropy Sex. The heating rate dependence of the relaxation time at the glass transition temperature was investigated to measure the kinetic fragility. A positive correlation between the thermodynamic and kinetic fragilities could be established in Mg-based BMG-forming liquids on the basis of Adam-Gibbs equation in contrast to a number of other BMGs.

scholarly journals Physical Aging Behavior of a Glassy Polyether

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 954
Author(s):  
Xavier Monnier ◽  
Sara Marina ◽  
Xabier Lopez de Pariza ◽  
Haritz Sardón ◽  
Jaime Martin ◽  
...  
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Physical Aging ◽  
Glassy State ◽  
Aging Behavior ◽  
Scanning Calorimetry ◽  
Narrow Temperature Range ◽  
Glass Forming ◽  
Fast Scanning Calorimetry

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.

scholarly journals Effects of Annealing on Enthalpy Recovery and Nanomechanical Behaviors of a La-Based Bulk Metallic Glass

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 579
Author(s):  
Ting Shi ◽  
Lanping Huang ◽  
Song Li
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Structural Relaxation ◽  
Supercooled Liquid ◽  
Supercooled Liquid Region ◽  
Liquid Region ◽  
Nanoindentation Measurement

Structural relaxation and nanomechanical behaviors of La65Al14Ni5Co5Cu9.2Ag1.8 bulk metallic glass (BMG) with a low glass transition temperature during annealing have been investigated by calorimetry and nanoindentation measurement. The enthalpy release of this metallic glass is deduced by annealing near glass transition. When annealed below glass transition temperature for 5 min, the recovered enthalpy increases with annealing temperature and reaches the maximum value at 403 K. After annealed in supercooled liquid region, the recovered enthalpy obviously decreases. For a given annealing at 393 K, the relaxation behaviors of La-based BMG can be well described by the Kohlrausch-Williams-Watts (KWW) function. The hardness, Young’s modulus, and serrated flow are sensitive to structural relaxation of this metallic glass, which can be well explained by the theory of solid-like region and liquid-like region. The decrease of ductility and the enhancement of homogeneity can be ascribed to the transformation from liquid-like region into solid-like region and the reduction of the shear transition zone (STZ).

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

Pharmaceutics ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 425 ◽  
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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