scholarly journals Fe-Co-B Soft Magnetic Ribbons: Crystallization Process, Microstructure and Coercivity

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1639
Author(s):  
Anna Wojcik ◽  
Wojciech Maziarz ◽  
Maciej Kowalczyk ◽  
Robert Chulist ◽  
Maciej Szlezynger ◽  
...  
Keyword(s):  
Heating Rate ◽  
Volume Fraction ◽  
Soft Magnetic ◽  
Microstructural Investigation ◽  
Transmission Electron ◽  
Heat Treated ◽  
Melt Spun ◽  
Mean Size ◽  
Residual Amorphous Matrix

In this work, a detailed microstructural investigation of as-melt-spun and heat-treated Fe67Co20B13 ribbons was performed. The as-melt-spun ribbon was predominantly amorphous at room temperature. Subsequent heating demonstrated an amorphous to crystalline α-(Fe,Co) phase transition at 403 °C. In situ transmission electron microscopy observations, carried out at the temperature range of 25–500 °C and with the heating rate of 200 °C/min, showed that the first crystallized nuclei appeared at a temperature close to 370 °C. With a further increase of temperature, the volume of α-(Fe,Co) crystallites considerably increased. Moreover, the results showed that a heating rate of 200 °C/min provides for a fine and homogenous microstructure with the α-(Fe,Co) crystallites size three times smaller than when the ribbon is heated at 20 °C/min. The next step of this research concerned the influence of both the annealing time and temperature on the microstructure and coercivity of the ribbons. It was shown that annealing at 485 °C for a shorter time (2 s) led to materials with homogenous distribution of α-(Fe,Co) crystallites with a mean size of 30 nm dispersed in the residual amorphous matrix. This was reflected in the coercivity (20.5 A/m), which significantly depended on the volume fraction of crystallites, their size, and distribution.

scholarly journals Synthesis and Characterization of Lixfepo4/C-Ppy Composite Cathode Material with Excess of Li+ Doping

2019 ◽  
Vol 9 (2) ◽  
pp. 5254-5257
Keyword(s):  
Composite Cathode ◽  
Chemical Precipitation ◽  
Polymerization Process ◽  
Step Method ◽  
Xrd Pattern ◽  
Li Doping ◽  
Unit Cell Size ◽  
Transmission Electron ◽  
Heat Treated

In-situ Polypyrrole (PPy) coating was performed on the surface of LixFePO4 /C (x=0.95 to 1.20) particles using iron (III) tosylate as oxidizer. The composite material LixFePO4 /C (x=0.95 to 1.20) was synthesized by two step method. FePO4 /polyaniline particles were first synthesized by chemical precipitation and were further heat treated with lithium acetate and sucrose under reduced atmosphere. XRD pattern confirms that Li+ addition to LiFePO4 has increased interplaner spacing and of the unit cell size. Impurity phase appears with x=1.15 and 1.20 which further disappears after polymer coating. After polymerization process the XRD pattern shows Li0.05FePO4 and LiFePO4 phases and both the phases have same electrochemical behavior. Morphology of the LixFePO4 /C and LixFePO4 /C-PPy was studied by using FE-SEM and it was found that particles are spherical with size range below 200nm. Transmission Electron Microscope (TEM) also confirms that LixFePO4 /C isolated particles were well encapsulated within the polymer matrix

scholarly journals Fabrication of Metastable Crystalline Nanocomposites by Flash Annealing of Cu47.5Zr47.5Al5 Metallic Glass Using Joule Heating

Nanomaterials ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 84 ◽  
Author(s):  
Ilya Okulov ◽  
Ivan Soldatov ◽  
Ivan Kaban ◽  
Baran Sarac ◽  
Florian Spieckermann ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Metallic Glass ◽  
Heating Rate ◽  
Joule Heating ◽  
Annealing Time ◽  
Volume Fraction ◽  
Glassy Material ◽  
Flash Annealing ◽  
Temperature Equilibrium

Flash Joule-heating was applied to the Cu47.5Zr47.5Al5 metallic glass for designing fully crystalline metastable nanocomposites consisting of the metastable B2 CuZr and low-temperature equilibrium Cu10Zr7 phases. The onset of crystallization was in situ controlled by monitoring resistivity changes in the samples. The effect of heating rate and annealing time on the volume fraction of the crystalline phases and mechanical properties of the nanocomposites was studied in detail. Particularly, an increase of the heating rate and a decrease of the annealing time lead to a lower number of equilibrium Cu10Zr7 precipitates and an increase of tensile ductility. Tailoring of these non-equilibrium microstructures and mechanical properties may not be possible unless one starts with a fully glassy material that opens new perspectives for designing metastable nanomaterials with unique physical properties.

An in Situ Transmission Electron Microscopy Study During NH3 Ambient Annealing of Cu-Cr Thin Films

1993 ◽  
Vol 317 ◽  
Author(s):  
Z. Atzmon ◽  
R. Sharma ◽  
J.W. Mayer ◽  
S.Q. Hong
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Transmission Electron Microscopy Study ◽  
Nitridation Process ◽  
Transmission Electron ◽  
Heat Treated

ABSTRACTNitridation of Cu-Cr alloy films under an NH3 ambient was studied using in situ transmission electron Microscopy. Cu-Cr thin films (40–100 nm) were deposited on a single crystal NaCl substrate by electron beam coevaporation, and were heat treated up to 750°C at 2.5–3.0 Torr NH3. The films were also vacuum (10-6 Torr) annealed under the same conditions for comparison. Initial observation of Cu and Cr crystallization occurred at 470°C for both environmental conditions. The nitridation process of Cr to form CrN was observed initially at 580°C and was followed by evolution of faceted Cu grain growth in the CrN Matrix.

Effect of heating rate during primary crystallization on soft magnetic properties of melt-spun Fe-B alloys

2017 ◽  
Vol 132 ◽  
pp. 68-72 ◽  
Author(s):  
B. Zang ◽  
R. Parsons ◽  
K. Onodera ◽  
H. Kishimoto ◽  
A. Kato ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Heating Rate ◽  
Primary Crystallization ◽  
Soft Magnetic Properties ◽  
Soft Magnetic ◽  
Melt Spun

scholarly journals Effect of Minor Amount of Sc on the Thermomechanical Treatment of Al-Zn-Mg-Cu-Zr Alloy

2021 ◽  
Author(s):  
Azam Beigi Kheradmand ◽  
Shamseddin Mirdamadi ◽  
Zahra Lalegani
Keyword(s):  
Thermomechanical Treatment ◽  
Volume Fraction ◽  
Cast Alloy ◽  
Tensile Tests ◽  
Minor Amount ◽  
Microstructural Investigation ◽  
Software Analysis ◽  
Heat Treated ◽  
The Matrix ◽  
Mechanical And Microstructural Properties

Abstract In this study, mechanical and microstructural properties of Al-Zn-Mg-Cu-Zr cast alloy with 0.1% Sc under homogeneous, dissolution, and T6 and thermomechanical treatments with the aim of increasing the volume fraction of MgZn2 and Al3(Sc,Zr) reinforcing sediments were examined by hardness, microscopic examinations and tensile tests and software analysis. The results showed that firstly, the hardness results are well proportional to the results of tensile properties of alloys and secondly, the strength of the alloy with thermomechanical treatments compared to T6 treatments increased from 492 MPa to 620 MPa and the elongation increased from 8% to 17% and 100 % upgraded. Microstructural investigation and fracture cross section showed that Al3(Sc,Zr) nanoparticles were evenly distributed among MgZn2 particles and the alloy fracture was of semi-ductile type and in the fracture section nanoparticles less than 10 nm were observed at the end of the dimples. Also, the volume fraction of nanoparticles in the whole microstructure of thermomechanical treatment samples was much higher than that of T6 heat treated samples, so that the percentage of Al3(Sc,Zr) sediments from less than 1% in T6 operation to 8.28% in quench-controlled thermomechanical operation (with 50% deformation) has arrived. QI index in thermomechanical treatment samples is 19% higher than T6 samples, so that this index has increased from 641 in T6 operation to 760 in samples under thermomechanical treatment due to sediment morphology, volume fraction of sediments, their uniform distribution in the matrix, and nano sized sediments in samples under thermomechanical treatment.

In Situ TEM Heating Study of the γ Lamellae Formation inside the α2 Matrix of a Ti-45Al-7.5Nb Alloy

2010 ◽  
Vol 146-147 ◽  
pp. 1365-1368 ◽  
Author(s):  
Li Mei Cha ◽  
Helmut Clemens ◽  
Gerhard Dehm ◽  
Zao Li Zhang
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ex Situ ◽  
In Situ Tem ◽  
Transmission Electron ◽  
Initial Stage ◽  
Heat Treated ◽  
The Matrix ◽  
In Situ Heating

In-situ heating transmission electron microscopy (TEM) was employed to investigate the initial stage of lamellae formation in a high Nb containing γ-TiAl based alloy. A Ti-45Al-7.5Nb alloy (at %), which was heat treated and quenched in a non-equilibrium state such that the matrix consists of ordered a2 grains, was annealed inside a TEM up to 750 °C. The in-situ TEM study reveals that g laths precipitate in the a2 matrix at ~ 750 °C possessing the classical Blackburn orientation relationship, i.e. (0001)a2 // (111)g and [11-20]a2 // <110]g. The microstructure of the in-situ TEM experiment is compared to results from ex-situ heating and subsequent TEM studies.

The Influence of the SPD Temperature on Superplasticity of Aluminium Alloys

2006 ◽  
Vol 503-504 ◽  
pp. 585-590 ◽  
Author(s):  
Rinat K. Islamgaliev ◽  
N.F. Yunusova ◽  
Ruslan Valiev
Keyword(s):  
Aluminium Alloys ◽  
Elevated Temperatures ◽  
Volume Fraction ◽  
High Pressure Torsion ◽  
Strain Rates ◽  
Angular Pressing ◽  
Thin Foils ◽  
Transmission Electron ◽  
In Situ Heating

Recent studies have demonstrated that ultrafinе-grainеd (UFG) alloys processed by equal channel angular pressing (ECAP) and high pressure torsion (HPT) can exhibit enhanced supеrplacticity at relatively low temperature and/or high strain rates. At the same time severe plastic deformation (SPD) of aluminium alloys is often carried out at elevated temperatures leading to various grain size and volume fraction of precipitates. The significance of the SPD temperature for commercial 1420 and 1421 aluminium alloys has been evaluated in this paper using in-situ heating of thin foils in the column of a transmission electron microscope. Superplastic characteristics of alloys processed at various ECAP temperatures are discussed.

scholarly journals A Nanocellulose Polypyrrole Composite Based on Tunicate Cellulose

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Dawei Zhang ◽  
Qing Zhang ◽  
Xin Gao ◽  
Guangzhe Piao
Keyword(s):  
Electron Microscopy ◽  
Electrical Conductivity ◽  
Ammonium Persulfate ◽  
High Electrical Conductivity ◽  
Chemical Polymerization ◽  
Transmission Electron ◽  
Mean Size ◽  
Polypyrrole Composite ◽  
Scanning Electron

The water-dispersed conductive polypyrrole (PPy) was prepared via thein situoxidative chemical polymerization by using ammonium persulfate (APS) as oxidant and tunicate cellulose nanocrystals (T-CNs) as a dopant and template for tuning the morphologies of PPy nanoparticles. Highly flexible paper-like materials of PPy/T-CNs nanocomposites with high electrical conductivity values and good mechanical properties were prepared. The structure of nanocomposites of PPy/T-CNs was investigated by using Fourier transform infrared spectroscopy. Scanning electron microscopy and transmission electron microscopy analyses of the composites revealed that PPy consisted of nanoparticles about 2.5 nm in mean size to form a continuous coating covered on the T-CNs. The diameters of the PPy nanoparticles increased from 10 to 100 nm with the increasing pyrrole amount. Moreover, electrical properties of the obtained PPy/T-CNs films were studied using standard four-probe technique and the electrical conductivity could be as high as 10−3 S/cm.

Microstructural Evolution and Mechanical Properties of Powder Hot Extruded Al-Zn-Mg-Cu Alloy

2009 ◽  
Vol 79-82 ◽  
pp. 2015-2018 ◽  
Author(s):  
Shao Qing Wang ◽  
Hua Shun Yu ◽  
Zhen Ya Zhang ◽  
Guang Hui Min ◽  
Hui Yu
Keyword(s):  
Electron Microscopy ◽  
Compositional Analysis ◽  
Hot Extrusion ◽  
Major Constituent ◽  
Cu Alloy ◽  
Transmission Electron ◽  
Heat Treated ◽  
Peak Aging ◽  
Mean Size ◽  
Al Matrix

In this study, an ultrastrength Al-10Zn-3.2Mg-2.3Cu alloy was fabricated by powder hot extrusion technique. The microstructures of powder, extruded and subsequently heat treated rods were investigated by means of X-ray diffractometer (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) with energy dispersive spectrometry (EDS) for compositional analysis. During extrusion, more MgZn2 compounds were precipitated from the supersaturated Al matrix and observed on the grain boundaries and in the grain interiors. The microstructure of as-extruded alloy is composed of Al matrix and MgZn2 phases in different shapes. After solution treating, the MgZn2 phases were mostly dissolved into matrix and the major constituent are Al7Cu2Fe phase as well as oxides. The mean size of grains was controlled to 2.5μm, and the major precipitates were GP zones and/or η’(MgZn2) phases in the Al matrix after peak-aging (T6) treatment (120°C for 20h). The ultimate tensile strength (σb), yield strength (σ0.2) and elongation (δ) are 745Mpa, 690MPa and 9.0%, respectively.

Micromagnetic Processes in Steels

1991 ◽  
Vol 232 ◽  
Author(s):  
A. D. Beale ◽  
M. G. Hetherington ◽  
J. P. Jakubovics ◽  
B. A. Lewis ◽  
C. B. Scruby
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Domain Structure ◽  
Magnetic Domain ◽  
Magnetic Domain Structure ◽  
Magnetoacoustic Emission ◽  
Transmission Electron ◽  
Heat Treated

ABSTRACTMagnetoacoustic emission (MAE) and Barkhausen emission (BE) measurements have been carried out on steel specimens heat treated to produce various microstructures ranging from martensitic/bainitic to ferritic/pearlitic. The magnetic domain structure of the specimens has been studied using transmission electron microscopy, and micromagnetic processes have been observed using an in-situ magnetizing device. The results are used in the interpretation of the MAE and BE measurements.

Sign in / Sign up

Export Citation Format

Share Document