scholarly journals The precipitation of nanocrystalline structure in the joule heated Fe72Al5Ga2P11C6B4 metallic glasses

2012 ◽  
Vol 48 (2) ◽  
pp. 319-324 ◽  
Author(s):  
N. Mitrovic ◽  
S. Kane ◽  
S. Roth ◽  
A. Kalezic-Glisovic ◽  
C. Mickel ◽  
...  
Keyword(s):  
Metallic Glasses ◽  
Amorphous Alloys ◽  
Amorphous Matrix ◽  
Annealing Treatment ◽  
Nanocrystalline Structure ◽  
Heating Power ◽  
Cast State ◽  
Current Annealing ◽  
Residual Amorphous Matrix ◽  
Crystalline Component

In this study, the evolution of the nanostructure on dc Joule heated Fe72Al5Ga2P11C6B4 metallic glass ribbons have been investigated. Heating power per square area (PS) was ranging between 0.8 to 7.1 W/cm2 in order to get various stages of relaxation or nanocrystallization. The crystallization starts after applying PS ? 4.35 W/cm2 and the sample consist of residual amorphous matrix, a magnetic crystalline component and also a non-magnetic crystalline component (relative abundance of Fe in the crystalline phase is about 35 %). XRD measurements show that crystalline samples after current annealing consist of Fe3B, FeC, FeP and Fe3P compounds. On TEM micrograph a broad distribution of shapes and sizes is noticed, the latter range from about 60 to 350 nm, increasing by applied heating power. The decrease of the electrical resistivity after each current annealing treatment is rather small in comparison with other Fe-based amorphous alloys (only about 1.5 % for the highest PS). Partial nanocrystallization leads to increase of coercive field (from HC ? 7 A/m in the amorphous as-cast state up to 45 A/m) attributed to precipitation of magnetically harder compounds (Fe3B and FeC).

Influence of the DC Current Annealing Treatment on Magnetotransport Properties of Soft-Magnetic Alloys with Amorphous Precursors

2006 ◽  
Vol 518 ◽  
pp. 313-318 ◽  
Author(s):  
N. Mitrović ◽  
Stefan Roth ◽  
S. Kane
Keyword(s):  
Structural Changes ◽  
Annealing Treatment ◽  
Nanocrystalline Structure ◽  
Supercooled Liquid ◽  
Supercooled Liquid Region ◽  
Liquid Region ◽  
Soft Magnetic Alloys ◽  
On Line ◽  
Current Annealing ◽  
Dc Current

Multistep current annealing (CA) treatments were performed on amorphous FINEMETtype Fe-Cu-V-Si-B, as well as on a novel Fe-Al-Ga-P-C-B alloy with a large supercooled liquid region, in order to optimize their magnetotransport properties. On-line and post-annealing electrical resistivity measurements, DSC, XRD and Mössbauer spectroscopy were used for characterization of structural changes evolved during CA treatments. Results on magnetoresistance (MR) and magnetoimpedance (MI) effects after CA in ribbon samples with relaxed amorphous as well as precipitated nanocrystalline structure are presented. Significant improvement in MI-response after CA up to Z/Z ≈ 50% was recorded at frequencies 2-3 MHz. The highest MI-element sensitivity was found for low magnetic field intensity where values of about 6 %/kA/m for samples of Fe-Al- Ga-P-C-B alloy were attained.

Modeling of Structures Nanocrystalline and Amorphous Alloys

2015 ◽  
Vol 245 ◽  
pp. 60-66
Author(s):  
Aleksandr Dubinets ◽  
Evgeny Pustovalov ◽  
Evgeny B. Modin ◽  
Aleksandr N. Fedorets ◽  
Vladimir Tkachev ◽  
...  
Keyword(s):  
Amorphous Alloys ◽  
Amorphous Matrix ◽  
Nanocrystalline Structure ◽  
Close Packing ◽  
Metal Alloys ◽  
Electron Wave ◽  
Amorphous Metal Alloys ◽  
Nanocrystalline And Amorphous ◽  
Resolution Electron ◽  
Electron Microscopes

In this paper discusses and demonstrates the possibility of modeling materials with amorphous and nanocrystalline structure using random close packing of atoms and nanoclusters models. Concordance structure of the real models alloys was evaluated by the radial distribution function obtained as a result of calculations, and in its modeled structures estimation. Modeling structure of the amorphous matrix and the spatial distribution of nanoclusters in two-component amorphous alloys with composition Fe80B20carried out by Ishikawa method. For modeling structure multicomponent amorphous metal alloys we developed correlation-spectral model of the amorphous matrix and nanoclusters. At modeling passing electron wave through the sample used a layered approach, and for the "visualization" imaging we modeled optical schemes of high-resolution electron microscopes.

Structure and Corrosion Behavior of Mg-Cu-Y-(Zn,Ni) Bulk Metallic Glasses

2015 ◽  
Vol 227 ◽  
pp. 23-26
Author(s):  
Rafał Babilas ◽  
Katarzyna Cesarz-Andraczke ◽  
Dorota Babilas ◽  
Wojciech Simka
Keyword(s):  
Corrosion Behavior ◽  
Metallic Glasses ◽  
Amorphous Alloys ◽  
Bulk Metallic Glasses ◽  
Pure Magnesium ◽  
Cast State ◽  
Surface Layers ◽  
Glassy Alloys ◽  
Ni Addition ◽  
Better Than

The work presents a structural and corrosion resistance analysis of Mg-based bulk metallic glasses in “as-cast” state. The studies were performed on bulk glassy samples in the form of plates. The structure analysis of the samples in “as-cast” state was carried out by the XRD and DSC methods. The corrosion behavior of the bulk glassy alloys and pure magnesium samples was studied by electrochemical measurements and immersion tests in 5% NaCl solution at room temperature. For the amorphous alloys the highest corrosion potential was achieved, indicating the formation of protective surface layers with Mg and Cu oxides. The corrosion behavior of the alloys with Zn and Ni addition was found to be better than pure magnesium.

EFFECT OF ANNEALING AT DIFFERENT TEMPERATURES ON THE STRUCTURE AND HARDNESS OF AL85Y8NI5CO2 ALLOY AMORPHOUS STRIPS

2018 ◽  
pp. 60-67
Author(s):  
A. G. Igrevskaya ◽  
A. I. Bazlov ◽  
N. Yu. Tabachkova ◽  
D. V. Louzguine ◽  
V. S. Zolotorevskiy
Keyword(s):  
Heat Treatment ◽  
Amorphous Alloys ◽  
Amorphous Matrix ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Maximum Value ◽  
Transmission Electron ◽  
Aluminum Solid Solution ◽  
Different Temperatures ◽  
Residual Amorphous Matrix

Aluminum-based metallic glasses are the new promising family of materials. However, the effect of heat treatment on the structure and properties of Al–Y–Ni–Co amorphous alloys has not been widely studied so far. In this paper, Al85Y8Ni5Co2 amorphous alloy strips were obtained by hardening on a rotary copper wheel. The effect of vacuum annealing at temperatures ranging from 100 to 500 °C for 30 minutes on the structure and hardness of these strips was investigated. Transmission electron microscopy, X-ray diffraction analysis, and differential scanning calorimetry were used to study changes in the structure of strips after heat treatment. Vickers microhardness was measured to investigate the effect of annealing on the mechanical properties of strips. The results obtained allowed for the conclusions made about changes in hardness depending on the Al85Y8Ni5Co2 alloy strip structure. It was found that as the temperature rises, strip microhardness increases reaching a maximum value of 575±7 HV after annealing at 350 °C, then it decreases with a further increase in the annealing temperature. It was shown that the Al85Y8Ni5Co2 alloy strips remain completely amorphous and no crystalline phases are detected in their structures after annealing at temperatures up to 250 °C for 30 minutes. A sharp increase in hardness after annealing at 350 °C is associated with 10–30 nm nanocrystals of an aluminum solid solution formed in the amorphous matrix and surrounded by a residual amorphous matrix, while further hardness decrease is associated with the increasing sizes of these crystals and Al3Y and Al19Ni5Y3 intermetallics formed in the structure.

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 Role of Nanocrystallites of Al-Based Glasses and H2O2 in Degradation Azo Dyes

Materials ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 39
Author(s):  
Qi Chen ◽  
Zhicheng Yan ◽  
Hao Zhang ◽  
KiBuem Kim ◽  
Weimin Wang
Keyword(s):  
Metallic Glasses ◽  
Azo Dye ◽  
Amorphous Matrix ◽  
Nano Scale ◽  
Transmission Electron ◽  
Melt Spun ◽  
Degradation Ability ◽  
Tem Transmission Electron Microscopy ◽  
Dye Solutions

Al-based metallic glasses have a special atomic structure and should have a unique degradation ability in azo dye solutions. The Al88Ni9Y3 (Y3), Al85Ni9Y6 (Y6) and Al82Ni9Y9 (Y9) glassy ribbons are melt spun and used in degrading methyl orange (MO) azo dye solution with adding H2O2. With increasing cY, the as-spun ribbons have an increasing GFA (glass formability) and gradually decreased the degradation rate of MO solution. TEM (transmission electron microscopy) results show that the Y3 ribbon has nano-scale crystallites, which may form the channels to transport elements to the surface for degrading the MO solution. After adding H2O2, the degradation efficiency of Al-based glasses is improved and the Y6 ribbon has formed nano-scale crystallites embedded in the amorphous matrix and it has the largest improvement in MO solution degradation. These results indicate that forming nano-scale crystallites and adding H2O2 are effective methods to improve the degradation ability of Al-based glasses in azo dye solutions.

Hydrogen-induced amorphization and embrittlement resistance in Ti-based in situ composite with bcc-phase in an amorphous matrix

2007 ◽  
Vol 22 (2) ◽  
pp. 428-436 ◽  
Author(s):  
S. Jayalakshmi ◽  
J.P. Ahn ◽  
K.B. Kim ◽  
E. Fleury
Keyword(s):  
Hydrogen Embrittlement ◽  
Amorphous Alloys ◽  
Amorphous Matrix ◽  
Mechanical Tests ◽  
High Concentration ◽  
High Hydrogen ◽  
In Situ Composite ◽  
Bcc Phase ◽  
Embrittlement Resistance

We report the hydrogenation characteristics and mechanical properties of Ti50Zr25Cu25 in situ composite ribbons, composed of β-Ti crystalline phase dispersed in an amorphous matrix. Upon cathodic charging at room temperature, high hydrogen absorption up to ∼60 at.% (H/M = ∼1.2) is obtained. At such a high concentration, hydrogen-induced amorphization occurs. Mechanical tests conducted on the composite with varying hydrogen concentrations indicate that the Ti50Zr25Cu25 alloy is significantly resistant to hydrogen embrittlement when compared to conventional amorphous alloys. A possible mechanism that would contribute toward hydrogen-induced amorphization and hydrogen embrittlement is discussed.

Amorphousization and Superconducting Property for Zr-Nb Based Alloy

2014 ◽  
Vol 783-786 ◽  
pp. 2503-2508
Author(s):  
Daisuke Okai ◽  
Kentaro Mori ◽  
Gaku Motoyama ◽  
Hisamichi Kimura ◽  
Hidemi Kato
Keyword(s):  
Magnetic Susceptibility ◽  
Metallic Glasses ◽  
Melt Spinning ◽  
Amorphous Matrix ◽  
Superconducting Property ◽  
Arc Melting ◽  
Nanocrystalline Particles

The amorphousization of Zr65Nb35 alloy was performed. The Zr-Nb based alloys contained Al and Co elements were fabricated by arc-melting and melt-spinning methods. The superconducting property of the Zr(65-x)Nb35-xAlx (x = 0~15 at%) and Zr(65-x)Nb20Al15Cox alloys (x = 3~10 at%) was investigated by magnetic susceptibility measurements. The Zr(65-x)Nb20Al15Cox metallic glasses (x = 6~10 at%) with superconducting nanocrystalline particles dispersed in an amorphous matrix exhibited a superconductivity below about 3.5 K. The addition of Co element led drastically to the amorphousization of the superconducting Zr65Nb20Al15 alloy.

Crystallization of Amorphous Silicon-Aluminum thin Films: IN-SITU Observation and Thermal Analysis.

1991 ◽  
Vol 237 ◽  
Author(s):  
Toyohiko J. Konno ◽  
Robert Sinclair
Keyword(s):  
Activation Energy ◽  
Amorphous Alloys ◽  
Amorphous Matrix ◽  
In Situ Observation ◽  
Scanning Calorimetry ◽  
Transmission Electron ◽  
High Resolution Tem ◽  
Higher Temperature ◽  
Sputter Deposited

ABSTRACTThe crystallization of sputter-deposited Si/Al amorphous alloys was examined by transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). In-situ high-resolution TEM reveals the existence of an Al layer between the amorphous matrix and the growing crystalline phase. The activation energy for the growth is about 1.2eV, roughly corresponding to the activation energy of Si diffusion in Al. These two observations support the view that a crystallization mechanism, in which an Al buffer layer provides the shortest reaction path, is responsible for the reaction. The product microstructure exhibits secondary crystallization at a higher temperature.

scholarly journals A Conflict of Fineness and Stability: Platinum- and Palladium-Based Bulk Metallic Glasses for Jewellery

2020 ◽  
Author(s):  
O. S. Houghton ◽  
A. L. Greer
Keyword(s):  
Metallic Glasses ◽  
Bulk Metallic Glasses ◽  
Precious Metals ◽  
High Hardness ◽  
Scratch Resistance ◽  
Cast State ◽  
High Definition ◽  
Glass Forming ◽  
Thermoplastic Forming ◽  
Near Net Shape

For the metals used in jewellery, high hardness and the associated scratch resistance are much sought after. Conventional crystalline alloys for jewellery are alloyed and extensively processed (thermally and mechanically) to improve hardness, but it is difficult to reach values beyond 300 HV. The advent of bulk metallic glasses, based on precious metals and with hardness exceeding 300 HV in the as-cast state, is therefore of great interest for both jewellery and watchmaking. The non-crystalline structure of these materials not only gives high hardness, but also the opportunity to shape metals like plastics, via thermoplastic forming. For more traditional jewellery manufacture, bulk metallic glasses also exhibit high-definition and near-net-shape casting. Gold-based alloys have long dominated the consideration of bulk metallic glasses for jewellery as they can comply with 18K hallmarks. Although bulk metallic glasses based on platinum or palladium possess excellent thermoplastic formability, and are without known tarnishing problems, achieving useful glass-forming ability within the more restrictive hallmarking standards typically used for jewellery (≥95 wt.% Pt or Pd) is, at best, challenging. In this review, platinum- and palladium-based bulk metallic glasses are discussed, focusing on their potential application in jewellery and on the further research that is necessary.

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