Bulk metallic glass formation, composite, and magnetic propertiesof Fe-B-Nd based alloys

The glass formation in Fe-rich ternary Fe-B-Nd and quaternary (Fe,B,Nd)96Nb4 alloys has been studied and the best ternary and quaternary glass formers are located at Fe67B23Nd10 and (Fe68B25Nd7)Nb4 with critical diameters of 1 and 4 mm, respectively. For (Fe,B,Nd)96Nb4 alloys, the competing phases with glass were identified by monitoring the microstructure change. Fe14Nd2B was discovered to be one competing phase, which is the principle magnetic phase for Nd-Fe-B hard magnets. Composites with uniformly distributed Fe14Nd2B were formed for quaternary alloys with a diameter of 1.5 to 3 mm. Bulk hard magnets could be obtained by directly annealing the composites in a compositional area. A hard magnet with a coercivity of 1,100 kAm−1 and a maximum energy product, (BH)max, of 33 kJm–3 was obtained at (Fe67B23Nd10)96Nb4 by annealing. The combination of hard magnetic properties and the large critical sample size may make these alloys a commercially viable candidate for industrial applications.

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Nanocrystalline Nd-Fe-B Alloys for Polymer-Bonded Magnets Production

ISRN Nanotechnology ◽

10.5402/2012/438436 ◽

2012 ◽

Vol 2012 ◽

pp. 1-6

Author(s):

Aleksandar Grujić ◽

Vladan Ćosović ◽

Aleksandar Ćosović ◽

Jasna Stajić-Trošić

Keyword(s):

Magnetic Properties ◽

Exchange Coupling ◽

Magnetic Phase ◽

Coupling Effect ◽

Maximum Energy ◽

Soft Magnetic ◽

Nanocomposite Structure ◽

Maximum Energy Product ◽

Energy Product ◽

Composite Production

This study presents how different nanostructures of starting Nd-Fe-B particles have influence on magnetic properties of polymer-bonded Nd-Fe-B materials. Two types of nanocrystalline Nd-Fe-B alloys were used for polymer composite production by compression molding technique. The particles with low neodymium content (Nd-low) have nanocomposite structure with small exchange coupling effect between hard and soft magnetic phase. In other hand, practically monophase hard magnetic structure of Nd-Fe-B particles with stoichiometric neodymium content (Nd-stoich) shows improved magnetic properties. With increasing concentration of polymer matrix, the coercivity (Hcb), remanence (Br), and maximum energy product ((BH)max) decrease more prominenty for composites with stoichiometric Nd-Fe-B content.

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Improved thermal stability of hard magnetic properties in rapidly solidified RE–TM–B alloys

Journal of Materials Research ◽

10.1557/jmr.2008.0337 ◽

2008 ◽

Vol 23 (10) ◽

pp. 2733-2742 ◽

Cited By ~ 10

Author(s):

Z.W. Liu ◽

R.V. Ramanujan ◽

H.A. Davies

Keyword(s):

Thermal Stability ◽

Grain Size ◽

Magnetic Properties ◽

Elevated Temperature ◽

Melt Spinning ◽

Maximum Energy ◽

Maximum Energy Product ◽

Energy Product ◽

Rapidly Solidified ◽

Hard Magnetic Properties

Rapidly solidified nanocrystalline RE–TM–B (RE = Nd, Pr, Dy, TM = Fe, Co) alloys with enhanced hard magnetic properties were synthesized by melt spinning. The composition- and microstructure-dependent elevated temperature magnetic properties were investigated. The temperature coefficients of remanence (α) and coercivity (β) were determined. The effects of Pr substituting Nd, Co substituting Fe, Dy substituting RE, and grain size on the Curie temperature and thermal stability were studied. Co or Dy substitutions were found to have a significant beneficial effect on the thermal stability. Reducing grain size could also improve elevated temperature behavior. Maximum energy product (BH)max > 100 kJ/m3 could be obtained in compositionally optimized nanophase alloys at temperature of 473 K. Extremely low coefficients of α and β were realized in exchange coupled nanocomposite alloys. Bonded nanocomposite magnets with α = −0.052%/K and β = −0.0365%/K for 300–400 K were also successfully fabricated.

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EM of rapidly solidified permanent magnets

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100121399 ◽

1992 ◽

Vol 50 (1) ◽

pp. 198-199

Author(s):

Raja K. Mishra

Keyword(s):

Melt Spinning ◽

Permanent Magnets ◽

Dark Field Image ◽

Dark Field ◽

Maximum Energy ◽

Quench Rate ◽

Maximum Energy Product ◽

Energy Product ◽

Annular Dark Field ◽

Rapidly Solidified

The discovery of a new class of permanent magnets based on Nd2Fe14B phase in the last decade has led to intense research and development efforts aimed at commercial exploitation of the new alloy. The material can be prepared either by rapid solidification or by powder metallurgy techniques and the resulting microstructures are very different. This paper details the microstructure of Nd-Fe-B magnets produced by melt-spinning.In melt spinning, quench rate can be varied easily by changing the rate of rotation of the quench wheel. There is an optimum quench rate when the material shows maximum magnetic hardening. For faster or slower quench rates, both coercivity and maximum energy product of the material fall off. These results can be directly related to the changes in the microstructure of the melt-spun ribbon as a function of quench rate. Figure 1 shows the microstructure of (a) an overquenched and (b) an optimally quenched ribbon. In Fig. 1(a), the material is nearly amorphous, with small nuclei of Nd2Fe14B grains visible and in Fig. 1(b) the microstructure consists of equiaxed Nd2Fe14B grains surrounded by a thin noncrystalline Nd-rich phase. Fig. 1(c) shows an annular dark field image of the intergranular phase. Nd enrichment in this phase is shown in the EDX spectra in Fig. 2.

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Effects of Magnetic Powder Loading on Mechanical Properties and Magnetic Properties of Natural Rubber

Advances in Science and Technology ◽

10.4028/www.scientific.net/ast.45.1423 ◽

2006 ◽

Vol 45 ◽

pp. 1423-1428

Author(s):

Somsak Woramongconchai ◽

Chatchawan Lohitvisat ◽

Aree Wichainchai

Keyword(s):

Mechanical Properties ◽

Magnetic Properties ◽

Coercive Force ◽

Natural Rubber ◽

Barium Ferrite ◽

Maximum Energy ◽

Magnetic Powder ◽

Elongation At Break ◽

Maximum Energy Product ◽

Energy Product

The effect of magnetic powders and powders loading on magnetic properties and mechanical properties of magnetic rubbers were studied. The natural rubber with magnetic powders, Barium ferrite, Neodymium iron boron, were used as starting materials to prepare magnetic rubbers. Barium ferrite (BaO.6F2O3) powders had been sintered at 1285 oC for 30 hours to improve its crystal structure. The physical properties of magnetic rubbers, residual flux density (Br), coercive force (Hc), maximum energy product (BHmax), hardness and density, had a trend to increase as enhancing magnetic powders loading. However, some properties such as, intrinsic coercive force (Hci), tensile strength and elongation at break, had a trend to decrease when the magnetic powder loading was increased. Magnetic properties of the anisotropic type, sintered powders, were higher than isotropic type, non-sintered powders, except the Hci because anisotropic magnetic rubber indicated crystal orientation in the same direction.

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Replacement of NdFeB by Ferrite Magnets

Materials Science Forum ◽

10.4028/www.scientific.net/msf.912.106 ◽

2018 ◽

Vol 912 ◽

pp. 106-111

Author(s):

Marcos Flavio de Campos ◽

Daniel Rodrigues ◽

Jose Adilson de Castro

Keyword(s):

Wind Turbines ◽

Maximum Energy ◽

High Resistivity ◽

Relevant Issue ◽

Demagnetizing Field ◽

Ndfeb Magnets ◽

Electric Cars ◽

Maximum Energy Product ◽

Energy Product ◽

Proper Volume

The replacement of NdFeB magnets by ferrite magnets is discussed. For motors, remanence is relevant, implying in a volume three times that of NdFeB, when the relevant index of merit is remanence. However, if the relevant issue is the BHmax (maximum energy product), the volume for replacement should be ten times larger. The high resistivity of ferrites is a big advantage for motors. The temperature of operation is also relevant, because NdFeB magnets loss coercivity even with small increase of temperature. Different applications are discussed, as for instance, motors for electric cars and wind turbines. The choice of the proper volume depends on the evaluation of demagnetizing field in the condition of operation.

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Bulk Nanocrystalline Permanent Magnets by Selective Laser Melting

Practical Metallography ◽

10.1515/pm-2021-0055 ◽

2021 ◽

Vol 58 (10) ◽

pp. 630-643

Author(s):

F. Trauter ◽

J. Schanz ◽

H. Riegel ◽

T. Bernthaler ◽

D. Goll ◽

...

Keyword(s):

Additive Manufacturing ◽

Field Strength ◽

Selective Laser Melting ◽

Permanent Magnets ◽

Maximum Energy ◽

Laser Melting ◽

Maximum Energy Product ◽

Energy Product ◽

Bulk Nanocrystalline ◽

Micrometer Scale

Abstract Fe-Nd-B powders were processed by additive manufacturing using laboratory scale selective laser melting to produce bulk nanocrystalline permanent magnets. The manufacturing process was carried out in a specially developed process chamber under Ar atmosphere. This resulted in novel types of microstructures with micrometer scale clusters of nanocrystalline hard magnetic grains. Owing to this microstructure, a maximum coercive field strength (coercivity) μ0Hc of 1.16 T, a remanence Jr of 0.58 T, and a maximum energy product (BH)max of 62.3 kJ/mm3could, for example, be obtained for the composition Nd16.5-Pr1.5-Zr2.6-Ti2.5-Co2.2-Fe65.9-B8.8.

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High-Throughput Screening of Rare-Earth-Lean Intermetallic 1-13-X Compounds for Good Hard-Magnetic Properties

Metals ◽

10.3390/met9101096 ◽

2019 ◽

Vol 9 (10) ◽

pp. 1096 ◽

Cited By ~ 2

Author(s):

Georg Krugel ◽

Wolfgang Körner ◽

Daniel F. Urban ◽

Oliver Gutfleisch ◽

Christian Elsässer

Keyword(s):

Rare Earth ◽

High Throughput ◽

High Throughput Screening ◽

Spontaneous Magnetization ◽

Anisotropy Field ◽

Structure Type ◽

Anisotropy Constant ◽

Maximum Energy ◽

Maximum Energy Product ◽

Energy Product

By computational high-throughput screening, the spontaneous magnetization M s , uniaxial magnetocrystalline anisotropy constant K 1 , anisotropy field H a , and maximum energy product ( B H ) max are estimated for ferromagnetic intermetallic phases with a tetragonal 1-13-X structure related to the LaCo 9 Si 4 structure type. For SmFe 13 N, a ( B H ) max as high as that of Nd 2 Fe 14 B and a comparable K 1 are predicted. Further promising candidates of composition SmFe 12 AN with A = Co, Ni, Cu, Zn, Ga, Ti, V, Al, Si, or P are identified which potentially reach (BH) max values higher than 400 kJ/m 3 combined with significant K 1 values, while containing almost 50% less rare-earth atoms than Nd 2 Fe 14 B.

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Effect of Dysprosium Content on the Magnetic Properties of Nanocrystalline (Pr0.25Nd0.75)10-xDyxFe82Co2B6 Alloys

Materials Science Forum ◽

10.4028/www.scientific.net/msf.789.28 ◽

2014 ◽

Vol 789 ◽

pp. 28-31 ◽

Cited By ~ 2

Author(s):

He Wei Ding ◽

Chun Xiang Cui ◽

Ji Bing Sun

Keyword(s):

Magnetic Properties ◽

Melt Spinning ◽

Maximum Energy ◽

Vibrating Sample Magnetometer ◽

X Ray ◽

Maximum Energy Product ◽

Energy Product ◽

Intrinsic Coercivity ◽

Electronic Microscope ◽

Microstructure And Magnetic Properties

(Pr0.25Nd0.75)10-xDyxFe82Co2B6(x=0~0.3) ribbons were prepared by melt spinning at 25m/s and subsequent annealing. The effect of Dy content on the microstructure and magnetic properties of the ribbons has been investigated by X-ray diffractometer (XRD), scanning electronic microscope (SEM) and vibrating sample magnetometer (VSM). The magnetic properties related to the Dy content were characterized. Intrinsic coercivity of 598kA/m, remanence of 0.58T, and the maximum energy product (BH)max of 43kJ/m3 were achieved in (Pr0.25Nd0.75)9.8Dy0.2Fe82Co2B6 after annealing at 700°C for 10 minutes.

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Microstructure Of Fe-Nd-B Alloys Tailored To Approach Theoretical Coercrvtty Limits

Microscopy and Microanalysis ◽

10.1017/s1431927600013453 ◽

1999 ◽

Vol 5 (S2) ◽

pp. 26-27

Author(s):

Kannan M. Krishnan ◽

Er. Girt ◽

E. C. Nelson ◽

G. Thomas ◽

Ferdinand Hofer

Keyword(s):

Magnetic Particles ◽

Permanent Magnets ◽

Spontaneous Magnetization ◽

Particle Interaction ◽

Maximum Energy ◽

Interacting Particles ◽

Maximum Energy Product ◽

Energy Product ◽

Oriented Samples ◽

The Difference

Performance of permanent magnets for a variety of applications is often determined by the maximum energy product (BH)max. In order to obtain high (BH)max permanent magnetic materials have to have large coercivity. In theory the coercive field of ideally oriented, non-interacting, single domain, magnetic particles, assuming Kl is much bigger than K2, was shown to be He = 2K1/Ms - N Ms, where Kl and K2 are the magnetocrystalline anisotropy constants, Ms is the spontaneous magnetization and N is the demagnetization factor. For randomly oriented non-interacting particles the Stoner-Wohlfarth model predicts that the value of Hc decreases to about half. However, experimentally obtained values of the coercitive fields in permanent magnets are 3 to 10 and 2 times smaller for well oriented and randomly oriented samples, respectively. This discrepancy was attributed to inter-particle interaction and the microstructure of the permanent magnets. In order to understand the difference between the theoretically predicted and experimentally obtained results for He we prepared rapidly quenched, Nd-rich, NdxFe14B (2 < x < 150) ribbons.

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