Nanocrystalline and Nanostructured High-Performance Permanent Magnets

2001 ◽  
Vol 674 ◽  
Author(s):  
D. Goll ◽  
W. Sigle ◽  
G.C. Hadjipanayis ◽  
H. Kronmüller
Keyword(s):  
Magnetic Properties ◽  
High Performance ◽  
Permanent Magnets ◽  
Maximum Energy ◽  
High Quality ◽  
Hardening Mechanism ◽  
Temperature Dependences ◽  
Complex Correlation ◽  
Energy Products

ABSTRACTThe rather complex correlation between the microstructure and the magnetic properties is demonstrated for two types of high-quality RE-TM permanent magnets (pms), namely nanocrystalline RE2Fe14B (RE = Nd,Pr) and nanostructured Sm2(Co,Cu,Fe,Zr)17 pms. The detailed analysis of this correlation for both pm materials leads to a quantitative comprehension of the hardening mechanism enabling the optimization of their magnetic properties and temperature dependences. In the case of RE2Fe14B, isotropic bonded pms are fabricated showing maximum energy products in the order of 90 kJ/m3. In the case of Sm2(Co,Cu,Fe,Zr)17, magnets with excellent high-temperature magnetic properties are tailored. Hereby, the investigations in addition provide important clues to the evolution of the characteristic microstructural and magnetic properties and to the role of the involved elements.

Role of nanoscale interfacial defects on magnetic properties of the 2:17-type Sm–Co permanent magnets

2020 ◽  
Vol 816 ◽  
pp. 152620 ◽  
Author(s):  
Xin Song ◽  
Xianglong Zhou ◽  
Tao Yuan ◽  
Jingdong Wang ◽  
Ming Yue ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Permanent Magnets ◽  
Interfacial Defects

Role of Heat Treatment in Magnetic Properties of Fe-Co-Ni-Al-Cu-Ti Alloy

2012 ◽  
Vol 510-511 ◽  
pp. 394-398 ◽  
Author(s):  
S. Imran ◽  
M.S. Awan ◽  
M.N. Sarwar ◽  
S. Akhtar ◽  
M. Farooque
Keyword(s):  
Heat Treatment ◽  
Magnetic Properties ◽  
Single Phase ◽  
Permanent Magnets ◽  
X Ray ◽  
Casting Technique ◽  
Alloy Casting ◽  
The Matrix ◽  
Metallurgical Structure

Anisotropic (Fe-24Co-15Ni-7.5Al-3Cu-0.3Ti) permanent magnets were prepared by alloy casting technique. Samples were characterized for structural, microstructural and magnetic properties using x-ray diffractrometer (XRD), Scanning electron microscope (SEM) equiped with energy dispersive x-ray spectrometer and DC magnetometer. There is a relation between metallurgical structure and magnetic properties. The magnetic properties of this type of alloy depend on heat-treatment that is controlling the cooling rate in the presence of magnetic field and double aging. How magnetic properties vary with heat treatment is discussed in this work. XRD studied revealed that the alloy was single phase (bcc) with (110) as the major crystallographic plane. Optical and SEM micrographs showed the presence of (Ti,S)-rich precipitates which are randomly distributed in the matrix. Their composition was analyzed by EDX analysis.

scholarly journals Microstructure and Magnetic Properties of Ce14Fe78Co2B6 Nanopowders Prepared by Ball Milling at Low Temperature

2021 ◽  
Vol 7 (12) ◽  
pp. 160
Author(s):  
Marian Grigoras ◽  
Mihaela Lostun ◽  
Firuta Borza ◽  
Marieta Porcescu ◽  
George Stoian ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Low Temperature ◽  
Ball Milling ◽  
Liquid Nitrogen ◽  
High Performance ◽  
Permanent Magnets ◽  
X Ray Diffraction ◽  
Hard Magnetic Properties ◽  
Uniform Particle Size ◽  
Microstructure And Magnetic Properties

Ce14Fe78Co2B6 nanopowders with hard-magnetic properties have been successfully prepared by ball milling at low temperatures in liquid nitrogen. The morphology, structure, and magnetic properties of Ce14Fe78Co2B6 powders have been investigated using scanning electron microscopy, X-ray diffraction, and vibrating sample magnetometry, respectively. It was found that powder ball milling at low temperature in liquid nitrogen, has the advantage that the oxidation of powders is inhibited and the particles rapidly reach nanometric dimensions. In comparison to the Ce14Fe78Co2B6 powders prepared by ball milling at room temperature, the powders milled at low temperature present a more uniform particle size and no rare-earth oxides, which leads thus to remarkable magnetic properties. The nanocrystalline Ce14Fe78Co2B6 powders with optimum characteristics, prepared at low temperature, have the size of 153 nm or less, present a coercivity of 5.1 kOe, and a saturation magnetization of 113 emu/g after milling for 6 h at low temperature. Low temperature milling may become a promising technique for the fabrication of high performance powders used for permanent magnets preparation.

scholarly journals Development of a High-Performance-Ferrite Magnet Fabrication Process without Sintering Additives

2021 ◽  
Vol 59 (8) ◽  
pp. 551-559
Author(s):  
Pyeong-Yeol Yu ◽  
Min-Ho Kim ◽  
Young-Min Kang
Keyword(s):  
Magnetic Properties ◽  
Saturation Magnetization ◽  
High Performance ◽  
Secondary Phase ◽  
Batch Process ◽  
Maximum Energy ◽  
Magnetic Flux Density ◽  
Sintering Additives ◽  
Energy Product ◽  
Hard Magnetic Properties

Sintered M-type hexaferrites with the chemical formula of Sr0.3Ca0.4La0.3Fe9.8Co0.2-xMnxSi0.135O19-d (x = 0, 0.05, 0.1, 0.2) and Sr0.3Ca0.4La0.3Fe9.8-yCo0.2MnySi0.135O19-d (y = 0.05, 0.1, 0.2) were prepared by conventional solid station reaction routes. A high sintering density of more than 95% of the theoretical density was achieved in all hexaferrite samples when calcination was carried out at 1100 oC for 4 h, followed by sintering at 1230-1250 oC for 2 h without the use of sintering additives. High saturation magnetization and coercivity were achieved simultaneously at the x = 0.05 composition, where Mn replaces part of the Co. The secondary phase Fe2O3 generated by the initial addition of SiO2 was gradually reduced when the Fe contented was decreased in the Sr0.3Ca0.4La0.3Fe9.8-zCo0.15Mn0.05Si0.135O19-d samples, and a single M-type hexaferrite phase was confirmed in the Sr0.3Ca0.4La0.3Fe8.3Co0.15Mn0.05Si0.135O19-d (z = 1.5) sample, which also exhibited optimized hard magnetic properties, with a saturation magnetization of 4581 G and coercivity of 4771 Oe. Anisotropic sintered magnets were fabricated using the optimized composition, and showed excellent hard magnetic properties, with a remanent magnetic flux density of 4400 G and intrinsic coercivity of 4118 Oe, and a maximum energy product of 4.72 M·G·Oe. This result is very promising because high magnet performance can be achieved with a single batch process without the need for sintering additives during the process.

scholarly journals Gas Transport Phenomena and Polymer Dynamics in PHB/PLA Blend Films as Potential Packaging Materials

Polymers ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 647 ◽  
Author(s):  
Valentina Siracusa ◽  
Svetlana Karpova ◽  
Anatoliy Olkhov ◽  
Anna Zhulkina ◽  
Regina Kosenko ◽  
...  
Keyword(s):  
High Performance ◽  
Gas Transport ◽  
Gas Permeability ◽  
Point Of View ◽  
Segmental Mobility ◽  
Scanning Calorimetry ◽  
Blend Films ◽  
Spin Resonance ◽  
Temperature Dependences

Actually, in order to replace traditional fossil-based polymers, many efforts are devoted to the design and development of new and high-performance bioplastics materials. Poly(hydroxy alkanoates) (PHAS) as well as polylactides are the main candidates as naturally derived polymers. The intention of the present study is to manufacture fully bio-based blends based on two polyesters: poly (3-hydroxybutyrate) (PHB) and polylactic acid (PLA) as real competitors that could be used to replace petrol polymers in packaging industry. Blends in the shape of films have been prepared by chloroform solvent cast solution methodology, at different PHB/PLA ratios: 1/0, 1/9, 3/7, 5/5, 0/1. A series of dynamic explorations have been performed in order to characterize them from a different point of view. Gas permeability to N2, O2, and CO2 gases and probe (TEMPO) electron spin resonance (ESR) analyses were performed. Blend surface morphology has been evaluated by Scanning Electron Microscopy (SEM) while their thermal behavior was analyzed by Differential Scanning Calorimetry (DSC) technique. Special attention was devoted to color and transparency estimation. Both probe rotation mobility and N2, O2, and CO2 permeation have monotonically decreased during the transition from PLA to PHB, for all contents of bio-blends, namely because of transferring from PLA with lower crystallinity to PHB with a higher one. Consequently, the role of the crystallinity was elucidated. The temperature dependences for CO2 permeability and diffusivity as well as for probe correlation time allowed the authors to evaluate the activation energy of both processes. The values of gas transport energy activation and TEMPO rotation mobility are substantially close to each other, which should testify that polymer segmental mobility determines the gas permeability modality.

scholarly journals Influence of Melt-Pool Stability in 3D Printing of NdFeB Magnets on Density and Magnetic Properties

Materials ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 139 ◽  
Author(s):  
Mateusz Skalon ◽  
Michael Görtler ◽  
Benjamin Meier ◽  
Siegfried Arneitz ◽  
Nikolaus Urban ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Layer Thickness ◽  
Process Parameters ◽  
Permanent Magnets ◽  
Scanning Speed ◽  
Maximum Energy ◽  
Powder Layer ◽  
Influence Of Process Parameters ◽  
Layer Height ◽  
Melt Pool

The current work presents the results of an investigation focused on the influence of process parameters on the melt-track stability and its consequence to the sample density printed out of NdFeB powder. Commercially available powder of Nd7.5Pr0.7Fe75.4Co2.5B8.8Zr2.6Ti2.5 alloy was investigated at the angle of application in selective laser melting of permanent magnets. Using single track printing the stability of the melt pool was investigated under changing process parameters. The influence of changing laser power, scanning speed, and powder layer thickness on density, porosity structure, microstructure, phase composition, and magnetic properties were investigated. The results showed that energy density coupled with powder layer thickness plays a crucial role in melt-track stability. It was possible to manufacture magnets of both high relative density and high magnetic properties. Magnetization tests showed a significant correlation between the shape of the demagnetization curve and the layer height. While small layer heights are beneficial for sufficient magnetic properties, the remaining main parameters tend to affect the magnetic properties less. A quasi-linear correlation between the layer height and the magnetic properties remanence (Jr), coercivity (HcJ) and maximum energy product ((BH)max) was found.

Influence of Milling Time on Magnetic Properties and Microstructure of Sintered Nd-Fe-B Based Permanent Magnets

2018 ◽  
Vol 930 ◽  
pp. 445-448
Author(s):  
R.G.T. Fim ◽  
M.R.M. Silva ◽  
S.C. Silva ◽  
Julio Cesar Serafim Casini ◽  
P.A.P. Wendhausen ◽  
...  
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Permanent Magnets ◽  
Milling Time ◽  
Maximum Energy ◽  
Inhomogeneous Distribution ◽  
Maximum Energy Product ◽  
Grain Sizes ◽  
Energy Product

In this paper, the effect of the grain size on sintered Nd-Fe-B based permanent magnets was investigated. In order, the magnets were produced by different milling times at 200 rpm and then vacuum sintered at 1373 K for 60 minutes followed by cooling outside the furnace. The magnets either produced by lower and higher milling times (30 and 75 minutes) exhibited lower remanence and coercivity, due the inhomogeneous distribution of the grain sizes. The magnet produced by intermediary milling time (45 minutes) exhibited the highest properties among all samples, with remanence of 1.06 T, coercivity of 891.3 KA.m-1, maximum energy product of 211 KJ.m3and a squareness factor equal 0.92.

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