Effect of Nitridation Magnetic Properties of Nanocrystalline Fe-Co Alloy Powders

2010 ◽  
Vol 654-656 ◽  
pp. 1106-1109
Author(s):  
Ya Qiong He ◽  
Chang Hui Mao ◽  
Jian Yang
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Alloy Powder ◽  
High Energy ◽  
X Ray Diffraction ◽  
Powder Mixtures ◽  
X Ray ◽  
Transmission Electron ◽  
Nitridation Temperature ◽  
Microstructure And Magnetic Properties

Nanocrystalline Fe-Co alloy powders, which were prepared by high-energy mechanical milling, were nitrided under the mixing gas of NH3/H2 in the temperature range from 380°C to 510°C. X-ray diffraction (XRD) was used to analyze the grain size and reaction during the processing. The magnetic properties of the nitrided powders were measured by Vibrating Sample Magnetometer (VSM). The results show that with the appearance of Fe4N phase after nitride treatment, and the grain-size of FeCo phase decreases with the increase of nitridation temperature between 380°C to 450°C.The saturation magnetization of nitrided alloy powder treated at 480°C is about 18% higher than that of the initial Fe-Co alloy powder, accompanied by the reduction of the coercivity. Transmission electron microscope (TEM) was used, attempting to further analyze the effect of Fe4N phase on microstructure and magnetic properties of the powder mixtures.

MICROSTRUCTURE AND MAGNETIC PROPERTIES OF NANOSTRUCTURED Al2O3-20vol%Fe70Co30 COMPOSITE PREPARED BY HIGH ENERGY MECHANICAL MILLING

2009 ◽  
Vol 23 (06n07) ◽  
pp. 1383-1388 ◽  
Author(s):  
MASLEEYATI YUSOP ◽  
DELIANG ZHANG ◽  
MARCUS WILSON ◽  
NICK STRICKLAND
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Alloy Powder ◽  
Milling Time ◽  
High Energy ◽  
Composite Powders ◽  
Nanostructured Composite ◽  
Alloy Particles ◽  
Average Grain Size ◽  
Microstructure And Magnetic Properties

Al 2 O 3-20 vol % Fe 70 Co 30 composite powders have been prepared by high energy ball milling a mixture of Al 2 O 3 powder and Fe 70 Co 30 alloy powder. The Fe 70 Co 30 alloy powder was also prepared by mechanical alloying of Fe and Co powders using the same process. The effects of milling duration from 8 to 48 hours on microstructure and magnetic properties of the nanostructured composite powders have been studied by means of X-ray Diffractometry (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometry (VSM). It was found that the nanostructured composite powder particles with irregular shapes and Fe 70 Co 30 alloy particles being embedded in them formed after 8 hours of milling. The average grain size of the Al 2 O 3 matrix reduced drastically to less than 18nm after 16 hours of milling. On the other hand, the embedded alloy particles demonstrated almost unchanged average grain size in the range of 14-15nm. Magnetic properties of the powder compacts at room temperature were measured from hysteresis curves, and show strong dependence of the milling time, with the coercivity increasing from 67.1 up to 127.9kOe with increasing the milling time from 8 to 48 hours. The possible microstructural reasons for this dependence are discussed.

TEM Study of FePt and FePt:C/FePt Composite Double-Layered Thin Films

2013 ◽  
Vol 275-277 ◽  
pp. 1952-1955
Author(s):  
Ling Fang Jin ◽  
Xing Zhong Li
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Grain Size ◽  
Magnetic Properties ◽  
Composite Layer ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron

New functional nanocomposite FePt:C thin films with FePt underlayers were synthesized by noneptaxial growth. The effect of the FePt layer on the ordering, orientation and magnetic properties of the composite layer has been investigated by adjusting FePt underlayer thickness from 2 nm to 14 nm. Transmission electron microscopy (TEM), together with x-ray diffraction (XRD), has been used to check the growth of the double-layered films and to study the microstructure, including the grain size, shape, orientation and distribution. XRD scans reveal that the orientation of the films was dependent on FePt underlayer thickness. In this paper, the TEM studies of both single-layered nonepitaxially grown FePt and FePt:C composite L10 phase and double-layered deposition FePt:C/FePt are presented.

Grain Size Dependent Magnetic Properties of Nanocrystalline Sm [BE]Co [BD][BJ]/Cu

2001 ◽  
Vol 703 ◽  
Author(s):  
L. Bessais ◽  
C. Djéga-Mariadassou ◽  
J. Zhang ◽  
V. Lalanne ◽  
A. Percheron-Guégan
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Rietveld Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Size Dependent ◽  
Transmission Electron ◽  
Average Grain Size ◽  
Magnetic Metal ◽  
Chemical Distribution

ABSTRACTThe evolution of both micro structural and magnetic properties of the Sm[BE]Co[BD][BJ] Cu powder, is studied as a function of soft co-milling time. The average grain size in the range 20 - 50 nm was determined by transmission electron microscopy coupled with x-ray diffraction using the Rietveld method. The particle shape and chemical distribution were investigated by elemental mapping, using wavelength dispersive x-ray analysis with electron microprobe analysis. The coercivity evolution shows that an optimum value of 6 kOe is obtained after 5 h co-milling. The microstructure analysis indicates that both materials are well mixed in nanometer scale. This technique appears as a potential route to synthesize nanocrystalline Sm[BE]Co[BD][BJ] isolated by non-magnetic metal Cu.

Microstructure and Property Evolution of Cu90Zr10 Alloy in the Process of Mechanical Alloying

2013 ◽  
Vol 750-752 ◽  
pp. 667-670
Author(s):  
C.J. Li ◽  
L. Teng ◽  
J. Tan ◽  
Q. Yuan ◽  
J.J. Tang ◽  
...  
Keyword(s):  
Solid Solution ◽  
Grain Size ◽  
Mechanical Alloying ◽  
Alloy Powder ◽  
High Energy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Maximum Value ◽  
Average Grain Size ◽  
Energy Ball

Cu90Zr10 alloy powder was prepared by high-energy ball milling. The microstructure and property evolution of this alloy powder during mechanical alloying (MA) were investigated by using X-ray diffraction and optical microscopy (OM). The alloy powder with an average grain size of 10 - 40 nm was obtained, and the grain size was found to decrease gradually with increasing milling time. The microhardness reached a maximum value (about 295 Hv) after 30 h milling. The internal microstrain and the microhardness of the samples increased due to the grain refinement and solid solution during milling, and 10at.% Zr could be brought into Cu lattice by solid solution during MA. At last, the mechanisms of strengthening were discussed.

Magnetic CoFe2O4/carbon nanotubes composites: fabrication, microstructure and magnetic response

2014 ◽  
Vol 28 (12) ◽  
pp. 1450095 ◽  
Author(s):  
Panfeng Wang ◽  
Jingcai Xu ◽  
Yanbing Han ◽  
Bo Hong ◽  
Hongxiao Jin ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Magnetic Properties ◽  
Room Temperature ◽  
X Ray Diffraction ◽  
Targeting Therapy ◽  
X Ray ◽  
Transmission Electron ◽  
Tumor Hyperthermia ◽  
Temperature Time ◽  
Microstructure And Magnetic Properties

By combining the unique microstructure of carbon nanotubes (CNTs) with the good magnetism of CoFe 2 O 4 ferrites, CoFe 2 O 4/CNTs nanocomposites were prepared by the solvothermal method for the application of targeting therapy and tumor hyperthermia. X-ray diffraction (XRD), thermal gravity analysis (TGA), transmission electron microscope (TEM) and vibrating sample magnetometer (VSM) were introduced to study the influence of the solvothermal temperature, time and the CNTs content on the microstructure and magnetic properties of CoFe 2 O 4/CNTs nanocomposites. The diameter of CoFe 2 O 4 nanoparticles coating on the surface of CNTs and the saturation magnetization (Ms) increased with the solvothermal temperature. CoFe 2 O 4/CNTs nanocomposites prepared at 180°C, 200°C and 220°C exhibited superparamagnetism at room temperature, while the samples prepared at 240°C and 260°C presented ferromagnetism. And the solvothermal time and CNTs content slightly affected the microstructure and magnetic properties, Ms and coercivity (Hc) increased slightly with the increasing solvothermal time and the decreasing CNTs content.

scholarly journals Size Effect on the Structural and Magnetic Properties of Nanosized PerovskiteLaFeO3Prepared by Different Methods

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Nguyen Thi Thuy ◽  
Dang Le Minh
Keyword(s):  
Magnetic Properties ◽  
Electron Microscope ◽  
Room Temperature ◽  
High Energy ◽  
Ferromagnetic Behavior ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Electron ◽  
Co Precipitation

Nanosized LaFeO3material was prepared by 3 methods: high energy milling, citrate gel, and coprecipitation. The X-ray diffraction (XRD), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) show that the orthorhombic LaFeO3phase was well formed at a low sintering temperature of 500°C in the citrate-gel and co-precipitation methods. Scanning electron microscope (SEM) and transmission electron microscope (TEM) observations indicate that the particle size of the LaFeO3powder varies from 10 nm to 50 nm depending on the preparation method. The magnetic properties through magnetization versus temperatureM(T)and magnetization verses magnetic fieldM(H)characteristics show that the nano-LaFeO3exhibits a weak ferromagnetic behavior in the room temperature, and theM(H)curves are well fitted by Langevin functions.

Investigations on the Magnetic Properties of High-Coercivity Nd40Fe30Co15Al10B5 Bulk Amorphous Alloys

2005 ◽  
Vol 877 ◽  
Author(s):  
L. Bessais ◽  
C. Djëga-Mariadassou ◽  
N. X. Phuc
Keyword(s):  
Magnetic Properties ◽  
Amorphous Alloys ◽  
Magnetic Behavior ◽  
High Energy ◽  
High Coercivity ◽  
X Ray Diffraction ◽  
X Ray ◽  
Leading Role ◽  
Remanence Ratio ◽  
Transmission Electron

AbstractNd40Fe30Co15Al10B5 bulk amorphous prepared by high energy milling shows a coercivity of 8.1 kOe with a Curie temperature of 645 K. The controlled nanocrystallization enhances the coercivity to 20 kOe and the remanence ratio is equal to 0.59. The coexistence of two crystalline magnetic phases, ferromagnetic Nd2(Fe,Co,Al)14B and antiferromagnetic Nd6(Fe,Co,Al)14 are revealed by x-ray diffraction, high-resolution transmission electron microscopy, magnetization measurements, and Mössbauer spectrometry. The grain size for optimal magnetic properties is around 30 nm. The nucleation process may play a leading role in the high magnetic behavior.

MICROSTRUCTURE AND MAGNETIC PROPERTIES CHANGE OF Fe3O4 NANOPARTICLES SYNTHESIZED UNDER MAGNETIC FIELDS AT ROOM TEMPERATURE

2009 ◽  
Vol 23 (23) ◽  
pp. 2723-2731 ◽  
Author(s):  
JUN WANG ◽  
SIHUA XIA ◽  
SHIHE CAO
Keyword(s):  
Magnetic Properties ◽  
Magnetic Fields ◽  
Room Temperature ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
Promising Technique ◽  
X Ray ◽  
Transmission Electron ◽  
Co Precipitation ◽  
Microstructure And Magnetic Properties

Magnetite nanoparticles have been synthesized by a co-precipitation method under magnetic fields (0~1 T) at room temperature. The as-prepared samples were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM), vibrating sample magnetometer (VSM) and their microstructure analysis were evaluated on a Mössbauer spectrum. It was found that the Fe 3 O 4 samples produced under a magnetic field of 1 T had a much higher saturation magnetization (15.3 emu/g) than those produced under 0.6 T (7.56 emu/g) and 0 T magnetic fields (6.59 emu/g). This interesting result implies that magnetic fields can affect the growth of Fe 3 O 4 nanoparticles and further change the microstructure and crystallinity of Fe 3 O 4 nanoparticles. It is expected that this process could also be a promising technique to improve the magnetic properties of other magnetic materials.

scholarly journals Multiscale Copper-µDiamond Nanostructured Composites

2012 ◽  
Vol 730-732 ◽  
pp. 925-930
Author(s):  
Daniela Nunes ◽  
Vanessa Livramento ◽  
Horácio Fernandes ◽  
Carlos Silva ◽  
Nobumitsu Shohoji ◽  
...  
Keyword(s):  
Pure Copper ◽  
Thermal Stabilization ◽  
Hot Extrusion ◽  
Processing Parameters ◽  
High Energy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Optimal Processing ◽  
Novel Approach ◽  
Transmission Electron

Nanostructured copper-diamond composites can be tailored for thermal management applications at high temperature. A novel approach based on multiscale diamond dispersions is proposed for the production of this type of materials: a Cu-nDiamond composite produced by high-energy milling is used as a nanostructured matrix for further dispersion of micrometer sized diamond. The former offers strength and microstructural thermal stability while the latter provides high thermal conductivity. A series of Cu-nDiamond mixtures have been milled to define the minimum nanodiamond fraction suitable for matrix refinement and thermal stabilization. A refined matrix with homogenously dispersed nanoparticles could be obtained with 4 at.% nanodiamond for posterior mixture with mDiamond and subsequent consolidation. In order to define optimal processing parameters, consolidation by hot extrusion has been carried out for a Cu-nDiamond composite and, in parallel, for a mixture of pure copper and mDiamond. The materials produced were characterized by X-ray diffraction, scanning and transmission electron microscopy and microhardness measurements.

Structural changes in titanium dioxide nanocrystals during plastic deformation

2005 ◽  
Vol 38 (5) ◽  
pp. 749-756 ◽  
Author(s):  
Ulrich Gesenhues
Keyword(s):  
Structural Changes ◽  
Crystal Size ◽  
Lower Layer ◽  
High Energy ◽  
Primary Crystal ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Hall Method ◽  
Means Of Transmission

The polygonization of 200 nm rutile crystals during dry ball-milling at 10gwas monitored in detail by means of transmission electron microscopy (TEM) and X-ray diffraction (XRD). The TEM results showed how to modify the Williamson–Hall method for a successful evaluation of crystal size and microstrain from XRD profiles. Macrostrain development was determined from the minute shift of the most intense reflection. In addition, changes in pycnometrical density were monitored. Accordingly, the primary crystal is disintegrated during milling into a mosaic of 12–35 nm pieces where the grain boundaries induce up to 1.2% microstrain in a lower layer of 6 nm thickness. Macrostrain in the interior of the crystals rises to 0.03%. The pycnometrical density, reflecting the packing density of atoms in the grain boundary, decreases steadily by 1.1%. The results bear relevance to our understanding of plastic flow and the mechanism of phase transitions of metal oxides during high-energy milling.

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