Highly Refined Microstructures in Devitrified Alloys

1995 ◽  
Vol 400 ◽  
Author(s):  
L. Battezzati
Keyword(s):  
Free Energy ◽  
Amorphous Alloys ◽  
Slow Growth ◽  
Diffusion Mechanism ◽  
Interfacial Free Energy ◽  
Nucleation And Growth ◽  
Polymorphic Transformations ◽  
Chemical Effects ◽  
Electroless Ni ◽  
Nanometric Size

AbstractThe formation of nanosized microstructures from controlled devitrification of amorphous alloys is reviewed. The driving force for copious nucleation of crystals is discussed in terms of thermodynamic models for the free energy of crystallization and for the interfacial free energy. After fast nucleation and growth of crystals to nanometric size, there are evidences of a change in diffusion mechanism to slow growth. Examples are provided of primary processes in Fe-Zr-B and Al-Sm with data of XRD, TEM, DSC. Cases of eutectic and polymorphic transformations are also at hand (Ni-P, Cu-Ti-Al, Cu-Ti-Ni, Ti-Zr-Co-Cu-Al) showing that the thermodynamic and kinetic conditions leading to nanostructured materials are not unique.Finally chemical effects are discussed such as those of impurities in crystallization (e. g. Zr-based alloys), in leaching of Ni-Zr-Al and in deposition reaction of electroless Ni-P.

scholarly journals Investigation of Nucleation and Growth at a Liquid–Liquid Interface by Solvent Exchange and Synchrotron Small-Angle X-Ray Scattering

2021 ◽  
Vol 9 ◽  
Author(s):  
Elyse A. Schriber ◽  
Daniel J. Rosenberg ◽  
Ryan P. Kelly ◽  
Anita Ghodsi ◽  
J. Nathan Hohman
Keyword(s):  
Free Energy ◽  
Small Angle ◽  
Organic Ligand ◽  
Interfacial Free Energy ◽  
Nucleation And Growth ◽  
Inorganic Element ◽  
X Ray ◽  
Silver Chalcogenide ◽  
X Ray Scattering ◽  
Ray Scattering

Hybrid nanomaterials possess complex architectures that are driven by a self-assembly process between an inorganic element and an organic ligand. The properties of these materials can often be tuned by organic ligand variation, or by swapping the inorganic element. This enables the flexible fabrication of tailored hybrid materials with a rich variety of properties for technological applications. Liquid-liquid interfaces are useful for synthesizing these compounds as precursors can be segregated and allowed to interact only at the interface. Although procedurally straightforward, this is a complex reaction in an environment that is not easy to probe. Here, we explore the interfacial crystallization of mithrene, a supramolecular multi-quantum well. This material sandwiches a well-defined silver-chalcogenide layer between layers of organic ligands. Controlling mithrene crystal size and morphology to be useful for applications requires understanding details of its crystal growth, but the specific mechanism for this reaction remain only lightly investigated. We performed a study of mithrene crystallization at an oil-water interfaces to elucidate how the interfacial free energy affects nucleation and growth. We exchanged the oil solvent on the basis of solvent viscosity and surface tension, modifying the dynamic contact angle and interfacial free energy. We isolated and characterized the reaction byproducts via scanning electron microscopy (SEM). We also developed a high-throughput small angle X-ray scattering (SAXS) technique to measure crystallization at short reaction timescales (minutes). Our results showed that modifying interfacial surface energy affects both the reaction kinetics and product size homogeneity and yield. Our SAXS measurements reveal the onset of crystallinity after only 15 min. These results provide a template for exploring directed synthesis of complex materials via experimental methods.

Amorphous alloys synthesized by interface-assisted ion beam mixing in the Ag–W system with the largest positive heat of formation

2003 ◽  
Vol 18 (7) ◽  
pp. 1499-1501 ◽  
Author(s):  
R. F. Zhang ◽  
B. X. Liu
Keyword(s):  
Solid Solution ◽  
Free Energy ◽  
Amorphous Alloys ◽  
Structural Transition ◽  
Ion Beam ◽  
Amorphous State ◽  
Interfacial Free Energy ◽  
Heat Of Formation ◽  
Alloy Formation ◽  
Ion Beam Mixing

Amorphous alloys were synthesized by interface-assisted ion beam mixing in the W-rich portion of the Ag–W system. These alloys are characterized by the largest positive heat of formation among the transition-metal alloys and were formed through a two-step structural transition in the alternately deposited Ag–W films. First, during alternate deposition of the nano-sized Ag and W layers, the interfacial free energy drove the Ag–W interaction, which resulted in an intermediate body-centered-cubic (bcc) supersaturated solid solution. Second, the bcc solid solution transformed into an amorphous state upon irradiation at room temperature by 200-keV xenon ions. We report the experimental observations of the Ag–W amorphous alloy formation and a brief discussion concerning the effects of the interfacial free energy and ion irradiation dose on the structural transition observed in the Ag–W films.

Role of Interface in Ion Mixing or Thermal Annealing Induced Amorphization in Multilayers in Some Immiscible Systems

1995 ◽  
Vol 396 ◽  
Author(s):  
B.X. Liu ◽  
Z.J. Zhang ◽  
O. Jin ◽  
F. Pan
Keyword(s):  
Free Energy ◽  
Thermal Annealing ◽  
Amorphous Alloys ◽  
Amorphous Film ◽  
Interfacial Free Energy ◽  
Convex Shape ◽  
Multilayered Films ◽  
Glass Forming ◽  
Energetic State

AbstractSix binary metal systems were selected to study the possibility of forming amorphous alloys by ion mixing or thermal annealing in multilayered Films, i.e. the Ta-Cu, Zr-Nb, Zr-Ta, Y-Zr, Y-Mo and Y-Ta systems, featuring positive heats of formation (ΔHf) ranging from +3 to +40 kJ/mol. Firstly, the interfacial free energy consisting of a chemical and an elastic terms was calculated and added to the energetic state of the multilayers. It was found that the excess interfacial free energy increased with increasing the fraction of the interfacial atoms in the multilayers, and could raise the multilayers to an energy level intersecting with or being higher than thai of the amorphous phase possessing a typical convex shape. It is therefore possible to produce amorphous alloys in such systems, if the multilayered filins included enough fraction of the interfacial atoms. The multilayered samples were then designed and prepared accordingly and both ion mixing and thermal annealing under appropriate conditions resulted in the formation of a number of new amorphous alloys, confirming the above prediction based on the interfacial free energy concern. It is noted that the success of synthesising amorphous alloys by solid-state reaction in the immiscible systems develops a new glass forming technique, namely interface-generated spontaneous amorphization, which has a great potential to produce new and relatively thick amorphous films, e.g. a Ta72Cu28 amorphous film of 800 nm thick was obtained.

AEM analysis of crystallization in Ti-based amorphous alloys

1983 ◽  
Vol 41 ◽  
pp. 270-271
Author(s):  
A.R. Pelton ◽  
A.F. Marshall ◽  
Y.S. Lee
Keyword(s):  
Magnetic Properties ◽  
Amorphous Alloys ◽  
Amorphous Materials ◽  
Isothermal Annealing ◽  
Amorphous Matrix ◽  
Nucleation And Growth ◽  
Current Interest ◽  
Amorphous Films ◽  
Electrical And Magnetic Properties

Amorphous materials are of current interest due to their desirable mechanical, electrical and magnetic properties. Furthermore, crystallizing amorphous alloys provides an avenue for discerning sequential and competitive phases thus allowing access to otherwise inaccessible crystalline structures. Previous studies have shown the benefits of using AEM to determine crystal structures and compositions of partially crystallized alloys. The present paper will discuss the AEM characterization of crystallized Cu-Ti and Ni-Ti amorphous films.Cu60Ti40: The amorphous alloy Cu60Ti40, when continuously heated, forms a simple intermediate, macrocrystalline phase which then transforms to the ordered, equilibrium Cu3Ti2 phase. However, contrary to what one would expect from kinetic considerations, isothermal annealing below the isochronal crystallization temperature results in direct nucleation and growth of Cu3Ti2 from the amorphous matrix.

scholarly journals Curcuminoid-Tailored Interfacial Free Energy of Hydrophobic Fibers for Enhanced Biological Properties

2021 ◽  
Author(s):  
Wevernilson F. de Deus ◽  
Bruna M. de França ◽  
Josué Sebastian B. Forero ◽  
Alessandro E. C. Granato ◽  
Henning Ulrich ◽  
...  
Keyword(s):  
Free Energy ◽  
Interfacial Free Energy ◽  
Biological Properties

Modeling the Diffusion-Controlled Growth of Needle and Plate-Shaped Precipitates

2002 ◽  
Vol 731 ◽  
Author(s):  
Z. Guo ◽  
W. Sha
Keyword(s):  
Free Energy ◽  
Transformation Strain ◽  
Interfacial Free Energy ◽  
Growth Theory ◽  
Controlled Growth ◽  
Precipitate Morphology ◽  
Interface Kinetics ◽  
Diffusion Controlled ◽  
Precipitate Growth ◽  
Strain Stress

AbstractVarious theories have been developed to describe the diffusion-controlled growth of precipitates with shapes approximating needles or plates. The most comprehensive one is due to Ivantsov, Horvay and Cahn, and Trivedi (HIT theory), where all the factors that may influence the precipitate growth, i.e. diffusion, interface kinetics and capillarity, are accounted for within one equation. However, HIT theory was developed based on assumptions that transformation strain/stress and interfacial free energy are isotropic, which are not true in most of the real systems. An improved growth theory of precipitates of needle and plate shapes was developed in the present study. A new concept, the compression ratio, was introduced to account for influences from the anisotropy of transformation strain/stress and interfacial free energy on the precipitate morphology. Experimental evidence supports such compression effect. Precipitate growth kinetics were quantified using this concept. The improved HIT theory (IHIT theory) was then applied to study the growth of Widmanstatten austenite in ferrite in Fe-C-Mn steels. The calculated results agree well with the experimental observations.

Breakthrough of Sublimation Drying by Liquid Phase Deposition

2021 ◽  
Vol 314 ◽  
pp. 172-177
Author(s):  
Yuta Sasaki ◽  
Yousuke Hanawa ◽  
Masayuki Otsuji ◽  
Naozumi Fujiwara ◽  
Masahiko Kato ◽  
...  
Keyword(s):  
Free Energy ◽  
Liquid Phase ◽  
Film Thickness ◽  
Process Parameters ◽  
Interfacial Free Energy ◽  
The Other ◽  
Liquid Phase Deposition ◽  
Drying Method ◽  
Substrate Side ◽  
Drying Technology

Damage-free drying becomes increasingly difficult with the scaling of semiconductor devices. In this work, we studied a new sublimation drying technology for 3nm node and beyond. In order to investigate the collapse factor by conventional sublimation drying, we observed the pattern with cryo-SEM and revealed that the collapse occurred when the liquid film on the substrate solidified. Based on this result, we considered that it was important to deposit a solidified film uniformly from the substrate side to suppress collapse. Two key process parameters were evaluated to achieve the uniform formation of the solidified film. One is interfacial free energy and the other is film thickness of solution just before solidification. By optimizing two key parameters, it was successfully demonstrated to suppress pattern collapse of challenging devices. In this paper, we report on a new drying method: sublimation drying by LPD (Liquid-phase deposition).

ADSORPTION OF BENZENE AND ETHANOL UP TO HIGH RELATIVE PRESSURES ON FINELY DIVIDED SODIUM CHLORIDE: PART I. PARTICLE SIZE EFFECTS AND THE ADSORPTION OF BENZENE: PART II. THE LOWERING OF SURFACE FREE ENERGY BY ETHANOL

1961 ◽  
Vol 39 (6) ◽  
pp. 1360-1371 ◽  
Author(s):  
R. R. Weiler ◽  
J. Beeckmans ◽  
R. McIntosh
Keyword(s):  
Free Energy ◽  
Sodium Chloride ◽  
Surface Free Energy ◽  
Convex Surface ◽  
Plane Surface ◽  
Saturated Vapor ◽  
Thick Layer ◽  
Interfacial Free Energy ◽  
Relative Pressure ◽  
Adsorption Data

Adsorption of benzene has been studied using four samples of fine sodium chloride. The range of relative pressures employed extended to 0.99. The data were employed to show that a correction to the relative pressure should be applied because of the curvature of the surface. The correction was made in the form of a reduction of the apparent relative pressure by application of the Kelvin equation, since the relative pressure over a convex surface would be less than over a plane surface. The adsorption data at high relative pressures for several samples of salt could then be represented by a common curve. It was further concluded that the thick-layer theory of adsorption due to Frenkel, Halsey, and Hill was applicable to adsorption on salt. Adsorption data for ethanol were then obtained and the reduction of surface free energy of the salt by the saturated vapor was evaluated. This figure was then combined with van Zeggeren's and Benson's value of the solid–liquid interfacial free energy for salt and ethanol to provide a provisional value of the surface free energy of sodium chloride of 227 ergs cm−2.

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