scholarly journals Effect of Co Substitution on Crystallization and Magnetic Behavior of Fe85.45−xCoxCu0.55B14 Metallic Glass

Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 919
Author(s):  
Lukasz Hawelek ◽  
Tymon Warski ◽  
Patryk Wlodarczyk ◽  
Marcin Polak ◽  
Przemyslaw Zackiewicz ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Magnetic Behavior ◽  
Magnetic Core ◽  
Scanning Calorimetry ◽  
Cu Content ◽  
Transmission Electron ◽  
Heat Treated ◽  
Core Losses ◽  
Diffraction Patterns ◽  
Nanocrystalline Phases

The effects of Co for Fe substitution on magnetic properties, thermal stability and crystal structure of Fe85.45−xCoxCu0.55B14 (x = 0, 2.5, 5, 7.5, 10) melt spun amorphous alloys were investigated. The Cu content was firstly optimized to minimize the energy of amorphous phase formation by the use of a thermodynamic approach. The formation of crystalline α-Fe type phase has been described using differential scanning calorimetry, X-ray diffractometry and transmission electron microscopy. The classical heat treatment process (with heating rate 10 °C/min) in vacuum for wound toroidal cores was optimized in the temperature range from 280 to 430 °C in order to obtain the best magnetic properties (magnetic saturation Bs and coercivity Hc obtained from the B(H) dependencies) at 50 Hz frequency. For optimal heat-treated samples, the complex magnetic permeability in the frequencies 104–108 Hz at room temperature was measured. Finally, magnetic core losses were obtained for 1 T/50 Hz and 1.5 T/50 Hz values for samples annealed at T = 310 °C. An analysis of transmission electron microscope images and electron diffraction patterns confirmed that high magnetic parameters are related to the coexistence of the amorphous and nanocrystalline phases.

Microstructure and Magnetic Properties of Two Phase β+γ Ferromagnetic Co-Ni-Al Alloys

2009 ◽  
Vol 154 ◽  
pp. 145-150 ◽  
Author(s):  
Wojciech Maziarz ◽  
Jan Dutkiewicz ◽  
Rafał Wróblewski ◽  
Marcin Leonowicz
Keyword(s):  
Electron Microscopy ◽  
Magnetic Properties ◽  
Magnetic Phase ◽  
Scanning Calorimetry ◽  
Two Phase ◽  
Ferromagnetic Alloys ◽  
Transmission Electron ◽  
Heat Treated ◽  
Phase Transition Temperatures ◽  
Microstructure And Magnetic Properties

The microstructure, texture and magnetic properties of two ferromagnetic alloys of composition Co35Ni37Al28 and Co37Ni35Al28 (in at. %) were investigated with optical microscopy (OM), analytical transmission electron microscopy (TEM), scanning electron microscopy (SEM) techniques as well as a vibrating sample magnetometer (VSM). The alloys were plastically deformed and heat treated in order to promote the martensitic transformation. Differential scanning calorimetry (DSC) revealed a drop of Ms temperature due to the increase of Co content in the alloys. The elongated twinned grains of size about 200 m and small precipitates of  phase were identified with the OM techniques. The TEM observations showed the twinned L10 non modulated martensite within the elongated grains and a small amount of ordered ’ phase after the heat treatment. The chemical composition of different martensite grains was established using point analyses of a HAADF-EDS technique. The magnetic phase transition temperatures were determined on the deformed samples using VSM method.

EFFECT OF NANOCRYSTALLIZATION ANNEALING ON MAGNETIC PROPERTIES AND MAGNETOIMPEDANCE OF CO-BASE RIBBONS

2012 ◽  
Vol 05 ◽  
pp. 841-846
Author(s):  
AMIR KEYVANARA ◽  
REZA GHOLAMIPOUR ◽  
SHAMSEDIN MIRDAMADI ◽  
FARZAD SHAHRI ◽  
HOSSEIN SEPEHRI AMIN
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Magnetic Properties ◽  
Structural Studies ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Melt Spun ◽  
Melt Spun Ribbons ◽  
Nanocrystalline Phases

Melt spun ribbons of Co 64 Fe 4 Ni 2 B 19 Si 8 Cr 3 alloy have been prepared and the nanocrystallization process was carried out by the heat treatment of the as spun ribbons above the crystallization temperature. Structural studies of the samples have been performed by transmission electron microscopy and X-ray diffraction. Magnetic properties of the samples and magnetoimpedance measurements were investigated and it was revealed that magnetic properties and magnetoimpedance of the samples deteriorate by the formation of nanocrystalline phases.

Superplastic Deformation and Viscous Flow in an Zr-Based Metallic Glass at 410°C

1998 ◽  
Vol 554 ◽  
Author(s):  
T. G. Nieh ◽  
J. G. Wang ◽  
J. Wadsworth ◽  
T. Mukai ◽  
C. T. Liu
Keyword(s):  
Strain Rate ◽  
Supercooled Liquid ◽  
Supercooled Liquid Region ◽  
Liquid Region ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Single Strain ◽  
Transmission Electron ◽  
Heat Treated ◽  
Different Temperatures

AbstractThe thermal properties of an amorphous alloy (composition in at.%: Zr-10Al-5Ti-17.9Cu-14.6Ni), and particularly the glass transition and crystallization temperature as a function of heating rate, were characterized using Differential Scanning Calorimetry (DSC). X-ray diffraction analyses and Transmission Electron Microscopy were also conducted on samples heat-treated at different temperatures for comparison with the DSC results. Superplasticity in the alloy was studied at 410°C, a temperature within the supercooled liquid region. Both single strain rate and strain rate cycling tests in tension were carried out to investigate the deformation behavior of the alloy in the supercooled liquid region. The experimental results indicated that the alloy did not behave like a Newtonian fluid.

Crystal structure, microstructure, and magnetic properties of the Fe2CrSi nanostructured Heusler alloy elaborated by the mechanical alloying method

2020 ◽  
Vol 111 (8) ◽  
pp. 681-687
Author(s):  
Fatiha Djaidi ◽  
Hanane Mechri ◽  
Mohammed Azzaz
Keyword(s):  
Crystal Structure ◽  
Electron Microscopy ◽  
Magnetic Properties ◽  
Mechanical Alloying ◽  
Heusler Alloy ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Electron ◽  
Disordered Crystal ◽  
Microstructure And Magnetic Properties

Abstract The Fe2CrSi nanostructured Heusler alloy was prepared by mechanical alloying followed by heat treatment. The structure, microstructure, and magnetic properties of the samples were studied by the following analysis methods: X-ray diffraction, scanning electron microscopy with energy dispersive X-ray spectrometry, transmission electron microscopy, and a vibrating sample magnetometer. The a-Fe (Si, Cr) solid solution with a disordered body centered cubic (bcc) crystal structure was obtained after 24 h of milling. An example of the sample milled for 32 h with a disordered crystal structure a-Fe(Si, Cr) was chosen to investigate the transformation with temperature using differential scanning calorimetry. The effect of annealing temperatures on the structural, microstructural, and magnetic properties of the ordered Fe2CrSi Heusler phase for the sample milled for 32 h was investigated.

Mössbauer and magnetization studies of mechanically milled nanocrystalline Fe1–xAlx alloys

2015 ◽  
Vol 93 (11) ◽  
pp. 1257-1263
Author(s):  
S. Rajan ◽  
R. Shukla ◽  
A. Kumar ◽  
A. Vyas ◽  
S. Khan ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Magnetic Behavior ◽  
High Energy ◽  
Milling Process ◽  
Transmission Electron ◽  
Bulk Magnetization ◽  
Hyperfine Field Distributions ◽  
Equilibrium Process ◽  
Energy Ball ◽  
Evolution Of Microstructure

Changes in the magnetic behavior of Fe1–xAlx (x = 0.3, 0.4, 0.5, 0.6) powders during mechanical alloying have been studied. The ball milling process leads to formation of solid state reaction assisted by severe plastic deformation because of which crystallite size is reduced and as a result of which interesting magnetic properties are developed. The evolution of magnetic order in high-energy ball-milled Fe–Al solid solution is investigated using 57Fe Mössbauer spectroscopy and vibrating sample magnetometer. Mössbauer spectra and the hyperfine field distributions of all the samples show the presence of both magnetic and paramagnetic components in the samples. The corresponding bulk magnetization studies also show that the Al rich samples are also ferromagnetic, which can be attributed to the presence of disordered Fe-rich phases due to the non-equilibrium process of alloying. In Fe-rich samples, the formation of an off stoichiometric Fe3Al phase is favored while in the case of Al-rich samples both Al-rich phases and clustering of Fe and Al atoms are present. The systematic variation in the magnetic properties has been qualitatively correlated with the evolution of microstructure, reduction in grain size (obtained using transmission electron microscopy) and enhanced intergranular exchange coupling.

scholarly journals Tunable magnetism on the lateral mesoscale by post-processing of Co/Pt heterostructures

2015 ◽  
Vol 6 ◽  
pp. 1082-1090 ◽  
Author(s):  
Oleksandr V Dobrovolskiy ◽  
Maksym Kompaniiets ◽  
Roland Sachser ◽  
Fabrizio Porrati ◽  
Christian Gspan ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Magnetic Behavior ◽  
Basic Research ◽  
Post Processing ◽  
Transmission Electron ◽  
Spin Dependent Transport ◽  
Complementary Approach ◽  
Dependent Transport ◽  
High Degree

Controlling magnetic properties on the nanometer-scale is essential for basic research in micro-magnetism and spin-dependent transport, as well as for various applications such as magnetic recording, imaging and sensing. This has been accomplished to a very high degree by means of layered heterostructures in the vertical dimension. Here we present a complementary approach that allows for a controlled tuning of the magnetic properties of Co/Pt heterostructures on the lateral mesoscale. By means of in situ post-processing of Pt- and Co-based nano-stripes prepared by focused electron beam induced deposition (FEBID) we are able to locally tune their coercive field and remanent magnetization. Whereas single Co-FEBID nano-stripes show no hysteresis, we find hard-magnetic behavior for post-processed Co/Pt nano-stripes with coercive fields up to 850 Oe. We attribute the observed effects to the locally controlled formation of the CoPt L10 phase, whose presence has been revealed by transmission electron microscopy.

scholarly journals Quantitative analysis of magnetic spin and orbital moments from an oxidized iron (1 1 0) surface using electron magnetic circular dichroism

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Thomas Thersleff ◽  
Jan Rusz ◽  
Stefano Rubino ◽  
Björgvin Hjörvarsson ◽  
Yasuo Ito ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Circular Dichroism ◽  
Magnetic Circular Dichroism ◽  
Strong Dependence ◽  
Magnetic Behavior ◽  
Spin Moment ◽  
Transmission Electron ◽  
Oxidized Iron ◽  
Magnetic Spin ◽  
Circular Dichroïsm

Abstract Understanding the ramifications of reduced crystalline symmetry on magnetic behavior is a critical step in improving our understanding of nanoscale and interfacial magnetism. However, investigations of such effects are often controversial largely due to the challenges inherent in directly correlating nanoscale stoichiometry and structure to magnetic behavior. Here, we describe how to use Transmission Electron Microscope (TEM) to obtain Electron Magnetic Circular Dichroism (EMCD) signals as a function of scattering angle to locally probe the magnetic behavior of thin oxide layers grown on an Fe (1 1 0) surface. Experiments and simulations both reveal a strong dependence of the magnetic orbital to spin ratio on its scattering vector in reciprocal space. We exploit this variation to extract the magnetic properties of the oxide cladding layer, showing that it locally may exhibit an enhanced orbital to spin moment ratio. This finding is supported here by both spatially and angularly resolved EMCD measurements, opening up the way for compelling investigations into how magnetic properties are affected by nanoscale features.

Microstructural Evaluation of Boron Free and Boron Containing Heat-Treated Ti-35Nb-7.2Zr-5.7Ta Alloy

2012 ◽  
Vol 18 (2) ◽  
pp. 295-303 ◽  
Author(s):  
Pallab Majumdar
Keyword(s):  
X Ray Diffraction ◽  
Second Stage ◽  
Β Phase ◽  
Solution Treated ◽  
Α Phase ◽  
Treatment Conditions ◽  
Transmission Electron ◽  
Heat Treated ◽  
Microstructural Evaluation ◽  
Diffraction Patterns

AbstractThe microstructure of Ti-35Nb-7.2Zr-5.7Ta (TNZT) and Ti-35Nb-7.2Zr-5.7Ta-0.5B (TNZTB) alloys under different heat treatment conditions has been analyzed. The solution-treated and water-quenched TNZT sample consists mainly of β phase with a very small amount of fine athermal ω precipitate. Precipitation of α can be observed when solution-treated samples are directly aged at 580°C for 8 h. The microstructure of the samples subjected to single-stage aging at 300°C or 400°C consists of ω precipitates in equiaxed β grains. Second stage aging at 580°C for 8 h after first stage of aging at 300°C or 400°C results in the replacement of ω precipitates by secondary α. In all of these samples, the amount of ω or α phase was very small, and therefore they could not be detected by X-ray diffraction studies. However, analysis of selected area diffraction patterns obtained from transmission electron microscopy studies confirms their presence. The addition of boron leads to the formation of dispersed precipitates of TiB in the β matrix of the TNZT alloy and also refines the β grains in the microstructure. However, other microstructural features of the TNZTB alloy are similar to those of the TNZT alloy.

Direct Conversion of TiO2 Sol to Nanocrystalline Anatase at 85 °C

2002 ◽  
Vol 17 (6) ◽  
pp. 1507-1512 ◽  
Author(s):  
K. I. Gnanasekar ◽  
V. Subramanian ◽  
J. Robinson ◽  
K. I. Gnanasekar ◽  
K. I. Gnanasekar ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Fine Particles ◽  
Anatase Phase ◽  
Direct Conversion ◽  
Scanning Calorimetry ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Average Grain Size ◽  
Tio2 Sol ◽  
Diffraction Patterns

Nanocrystalline TiO2 anatase with particle size in the range of 5–7 nm has been prepared by in situ cracking of the sol at 85 °C, thereby avoiding the intermediate gel formation process. Hydrolysis of Ti(O-isoPr)4 was carried out in excess of 2-propanol to keep the suspension of fine particles from agglomeration. Differential thermal analysis, thermogravimetric analysis, differential scanning calorimetry, powder x-ray diffraction (XRD), and electron microscopy have been used to characterize the samples. Gel to crystalline conversion, which requires a temperature of at least 400 °C, can be achieved by digesting the TiO2 sol at 85 °C. XRD and selected area electron diffraction patterns show the presence of a small amount of brookite phase along with the major anatase phase. High-resolution transmission electron microscopy shows that the average grain size of TiO2 particle remains around 5–9 nm even when heated at 510 °C.

scholarly journals Influence of the Quenching Rate on the Structure and Magnetic Properties of the Fe-Based Amorphous Alloy

2016 ◽  
Vol 61 (1) ◽  
pp. 439-444 ◽  
Author(s):  
M. Nabiałek
Keyword(s):  
Magnetic Properties ◽  
Amorphous Alloy ◽  
Magnetic Measurements ◽  
Mössbauer Spectrometry ◽  
X Ray Diffraction ◽  
Quenching Rate ◽  
X Ray ◽  
Transmission Electron ◽  
Mossbauer Spectrometry ◽  
Diffraction Patterns

This paper presents the results of investigations into the structure, microstructure and magnetic properties of Fe61Co10Y8W1B20 amorphous alloy. The alloy samples were in two physical forms: (1) plates of approximate thickness 0.5 mm (so-called bulk amorphous alloys) and (2) a ribbon of approximate thickness 35 μm (so-called classic amorphous alloy). The investigations comprised: X-ray diffractometry, Mössbauer spectrometry, transmission electron microscopy, and selected magnetic measurements; all of the investigations were carried out on samples in the as-quenched state. Analysis of the obtained SEM and TEM images, X-ray diffraction patterns, Mössbauer spectrometry results and measurements of the magnetisation in a high magnetic field facilitated collectively the detailed description of the structure of the investigated alloy, which was found to depend on the quenching speed.

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