Nonequilibrium Microstructures for Ag–Ni Nanowires

2015 ◽  
Vol 21 (2) ◽  
pp. 491-497 ◽  
Author(s):  
Rajesh K. Rai ◽  
Chandan Srivastava
Keyword(s):  
Crystalline Phase ◽  
Thermal Processing ◽  
Isothermal Annealing ◽  
Amorphous Matrix ◽  
Phase Evolution ◽  
Peripheral Region ◽  
Axial Region ◽  
Amorphous Phases ◽  
Formation Kinetics ◽  
Nanocrystalline And Amorphous

AbstractThis work illustrates that a variety of nanowire microstructures can be obtained either by controlling the nanowire formation kinetics or by suitable thermal processing of as-deposited nanowires with nonequilibrium metastable microstructure. In the present work, 200-nm diameter Ag–Ni nanowires with similar compositions, but with significantly different microstructures, were electrodeposited. A 15 mA deposition current produced nanowires in which Ag-rich crystalline nanoparticles were embedded in a Ni-rich amorphous matrix. A 3 mA deposition current produced nanowires in which an Ag-rich crystalline phase formed a backbone-like configuration in the axial region of the nanowire, whereas the peripheral region contained Ni-rich nanocrystalline and amorphous phases. Isothermal annealing of the nanowires illustrated a phase evolution pathway that was extremely sensitive to the initial nanowire microstructure.

Effect of Annealing on the Curie Temperature in the Bulk Amorphous Alloys

2017 ◽  
Vol 68 (8) ◽  
pp. 1903-1907 ◽  
Author(s):  
Bartlomiej Jez
Keyword(s):  
Curie Temperature ◽  
Amorphous Alloys ◽  
Isothermal Annealing ◽  
Amorphous Matrix ◽  
Annealing Process ◽  
Amorphous Phases ◽  
Bulk Amorphous Alloys ◽  
Partial Crystallization ◽  
Curie Temperatures ◽  
Thermal Interference

The paper presents results of research for volumetric amorphous alloys Fe61+xCo10-XY8W1B20 where x = 0,12 in the shape of plater of 10mm x 5mm x 0.5mm diameter. Amorphous Samales were annealed at 953K for 10 minutes what caused their partial crystallization. As a result of the thermal interference in the volume of alloys, three different crystalline phases were formed aFe, Fe5Y and Fe3B. For samples after solidification and after thermal treatment thermomagnetic studiem were conducted. For amorphous alloys, only one ferro-paramagnetic transition was visible, and for the alloys after the isothermal annealing process there were two inflections on the curve .m0Ms (T) corresponding to the two Curie temperatures. These intersections came from two amorphous phases. As a result of the research, it was found that these alloys crystallized in the primal crystalization. Crystallization was the reason for the increase of the first Curie temperature of the amorphous matrix while retaining its decrease with cobalt additive. The value of the second Curie temperature in the alloys after heating was found to depend mainly on the size of the crystallization products and in particular on the Fe5Y crystallite size.

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 Revealing the perovskite formation kinetics during chemical vapour deposition

2020 ◽  
Vol 8 (42) ◽  
pp. 21973-21982
Author(s):  
Thierry Moser ◽  
Kerem Artuk ◽  
Yan Jiang ◽  
Thomas Feurer ◽  
Evgeniia Gilshtein ◽  
...  
Keyword(s):  
Chemical Vapour Deposition ◽  
Vapour Deposition ◽  
Perovskite Phase ◽  
Chemical Vapour ◽  
Phase Evolution ◽  
Formation Kinetics ◽  
Control Chemical ◽  
High Control

High control chemical vapour deposition of (Cs,FA)PbI3 perovskite provides insights into CVD kinetics and perovskite phase evolution.

scholarly journals Mechanistic insight of KBiQ2 (Q = S, Se) using panoramic synthesis towards synthesis-by-design

2021 ◽  
Author(s):  
Rebecca McClain ◽  
Christos D. Malliakas ◽  
Jiahong Shen ◽  
Jiangang He ◽  
Chris Wolverton ◽  
...  
Keyword(s):  
Crystalline Phase ◽  
Phase Evolution ◽  
X Ray Diffraction ◽  
Panoramic View ◽  
X Ray ◽  
Mechanistic Insight

This work uses in situ powder X-ray diffraction studies to observe crystalline phase evolution over the course of multiple K-Bi-Q (Q = S, Se) reactions, thereby constructing a “panoramic” view of each reaction from beginning to end.

scholarly journals Deformation-Induced Amorphization of Crystalline Particles in a Cu-Ti Metallic Glass

1986 ◽  
Vol 80 ◽  
Author(s):  
Eduardo A. Kamenetzky ◽  
Philip D. Asikenazy ◽  
Lee E. Tanner ◽  
William L. Johnson
Keyword(s):  
Amorphous Matrix ◽  
Structural Evolution ◽  
Convergent Beam Electron Diffraction ◽  
Transformation Process ◽  
Morphological Description ◽  
X Ray Diffraction ◽  
Initial Particle ◽  
X Ray ◽  
Amorphous Phases ◽  
Convergent Beam

AbstractCrystalline particles and grains embedded in Cu35Ti65 glass ribbons have been amorphized by isothermal cold rolling. The structural evolution has been studied by X-ray diffraction and TEM techniques. Initial particle morphologies are spherulitic and spherical, the latter with sizes ranging between 10 and 100 nm. The new amorphous phase seems to nucleate at crystalline-amorphous matrix interfaces. Initially there is a well defined interface between the new and the existing amorphous phases but it disappears as rolling progresses. Crystallites on a nanoscale still present in the final stages of particle amorphization have been observed by convergent beam electron diffraction. After sufficient deformation the consolidated ribbon becomes completely glassy. A morphological description of the transformation process in terms of crystal destabilization and solid-state particle melting is presented.

FERROMAGNETIC RESONANCE STUDY OF AMORPHOUS AND NANOCRYSTALLINE Fe81B13.5Si3.5C2 RIBBONS

2009 ◽  
Vol 23 (16) ◽  
pp. 3391-3402
Author(s):  
WEERAPHAT PON-ON ◽  
PONGTIP WINOTAI ◽  
I-MING TANG
Keyword(s):  
Ferromagnetic Resonance ◽  
Resonance Line ◽  
Isothermal Annealing ◽  
Amorphous Matrix ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffusion Controlled ◽  
Nano Grains ◽  
Relative Change ◽  
Kinetics Of

The nanocrystallization process in amorphous Fe 81 B 13.5 Si 3.5 C 2 ribbons caused by isothermal annealing below the crystallization temperature is studied. X-ray diffraction and Mossbauer spectroscopy measurements are used to identify the formation of new Fe containing compounds such as the ribbons annealed at various temperatures. The ferromagnetic resonance measurements for an as-cast ribbon and the 495°, 525°C and 600°C annealed ribbons exhibit a resonance line at 63.64 mT for φ = 0°. The sample annealed at 425°C shows two resonance peaks at 95.45 mT and 295.46 mT. These are due to the nanocrystalline α– Fe(Si) phase. The resonance-line widths are seen to broaden after the ribbons are annealed at 495°C and 525°C, at which time, the amorphous matrix crystallizes into nano-grains of α– Fe(Si) , t– Fe 2 B and t– Fe 3 B phases. The kinetics of the crystallization is discussed in terms of the relative change in the line width of the samples annealed at 495°C for different annealing times. These results yielded an Avrami exponent, n of 0.84 which is consistent with diffusion-controlled growth with a nucleation rate close to zero.

Phase Stability of Crystalline and Amorphous Phases and Formation of Nanostructure in Zr-Pd and Zr-Pt Alloys Under Electron Irradiation

2007 ◽  
Vol 1048 ◽  
Author(s):  
Yukichi Umakoshi ◽  
Takeshi Nagase ◽  
Takashi Hosokawa
Keyword(s):  
Electron Irradiation ◽  
Crystalline Phase ◽  
Amorphous State ◽  
Nano Composite ◽  
Phase Selection ◽  
Amorphous Phases ◽  
Nano Crystalline ◽  
Residual Amorphous Phase ◽  
Pt Alloys ◽  
Induced Crystallization

AbstractElectron irradiation induced phase transition behavior of Zr-Pd and Zr-Pt alloys was investigated focusing on phase selection in crystallization by thermal annealing and electron irradiation. Nano quasi-crystalline (QC) phase was formed by thermal crystallization in Zr66.7Pd33.3 and Zr80Pt20 alloys, while nano two-type f.c.c. super-saturated solid solutions were formed by irradiation induced crystallization at 298K. In Zr66.7Pt33.3 alloy, polycrystalline Zr5Pt3 and Zr9Pt11 phases transformed to two-type f.c.c. nano-crystalline phase through an amorphous state by crystal-to-amorphous-to-crystal (C-A-C) transition during electron irradiation. Nano-composite phase composed of f.c.c. super-saturated solid solution and residual amorphous phase was stable rather than an amorphous single phase, thermal equilibrium crystalline phase and quasi-crystalline phase under 2.0MV electron irradiation at 298K, resulting in the formation of nano-composite structure by irradiation induced amorphization and crystallization.

Simulation of the structure of GeAs4Te7 chalcogenide materials during memory switching

2014 ◽  
Vol 92 (7/8) ◽  
pp. 675-680 ◽  
Author(s):  
M. Popescu ◽  
F. Sava ◽  
A. Velea ◽  
A. Lőrinczi ◽  
I.D. Simandan
Keyword(s):  
Amorphous Phase ◽  
Crystalline Phase ◽  
Glass Formation ◽  
Structural Changes ◽  
Amorphous Matrix ◽  
Switching Process ◽  
High Resistivity ◽  
Spatial Constraints ◽  
Memory Switching ◽  
Chalcogenide Materials

The complex chalcogenides with excellent memory switching properties are mainly situated close to the border of glass formation domain. The simulation of the structural changes occurring during the memory switching process of a ternary chalcogenide composition has been carried out. The transition of a high resistivity GeAs4Te7 amorphous cluster with 120 atoms to a low resistivity crystalline cluster was analyzed. The coordination of atoms changes from that corresponding to 8-N coordination rule (two for tellurium, three for arsenic, and four for germanium) in the amorphous phase to six (the same for all atoms) in metastable crystalline phase. Because of spatial constraints exercised by the amorphous matrix, the amorphous cluster cannot expand. In these circumstances Te atoms seem to be over-coordinated (up to sixfold-coordinated). During the switching process, the atoms are moving on distances up to 4.0 Å. The average displacement is of 2.36 Å.

Microstructure of Gold Nano-Crystals from Nanometer to Micrometer Lengthscale in Gold Bulk Metallic Glass

2014 ◽  
Vol 983 ◽  
pp. 59-62
Author(s):  
Nirut Boonchu ◽  
Anan Lawan ◽  
Kamolchanok Thipayarat ◽  
Suphakit Pintasiri ◽  
Worasit Kanjanakijkasem ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Transmission Electron Microscope ◽  
Amorphous Matrix ◽  
Amorphous Solid ◽  
Phase Evolution ◽  
Copper Plate ◽  
Cooling Rates ◽  
Transmission Electron

Gold based bulk metallic glass was synthesized at with different quenching rates. Au54Ag5Pd2Cu24.3Si14.7 alloy ingots were cast into wedge shape and cone shape samples. The critical casting thickness of this alloy composition was found to be 4 mm when cast in copper mold. Completely amorphous structure as found in sections thinner than 4 mm when considering a infinite copper plate geometry. In locations with slower cooling rates, there are small fractions of transformed nanocrystals. The transmission electron microscope (TEM) study of Au54Ag5Pd2Cu24.3Si14.7 solidified microstructure could offer snap shots of nucleation and growth of crystals from nanometer to micrometer length-scale as evolved with different cooling rates. The phase evolution was recorded by transmission electron microscope study, electron diffraction and metallography using scanning electron microscope. The specimens comprised of both fully amorphous solid and nanocomposites which were the combination of nano-crystals of controlled sizes in amorphous matrix. Vickers hardness values increased to 350-450 Hv, when compared to sub 100-150 Hv level of conventional 18-k gold alloys as cast. The study offers a revolutionary way to create ultrahigh strength bulk metals that comprise of large percentage of nano-crystals in amorphous matrix.

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