Cobalt-free permanent magnet materials based on iron-rare-earth alloys (invited)

Hadjipanayis, G. C.; Hazelton, R. C.; Lawless, K. R.

doi:10.1063/1.333570

Cited by 160 publications

(24 citation statements)

References 12 publications

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“…8,10 Quite recently, however. Hadjipanayis, et al 11,12 and Croat, et al 13,14 have noticed that high coercive forces produced in melt spun R Fe B alloys originate from the formation of a stable compound which appears to have a tetragonal structure. This compound coincided with that which we found from a di erent approach.…”

Section: Introductionmentioning

confidence: 99%

Permanent magnet materials based on the rare earth-iron-boron tetragonal compounds

Sagawa¹,

Fujimura²,

Yamamoto³

et al. 1984

IEEE Trans. Magn.

748

188

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Structural and metallographic studies were carried out on the Nd Fe B alloy system as well as the Nd Fe B tetragonal compound on which record high energy mag nets have been developed using a powder metallurgical technique. The study on the new magnet has also been extended to other R Fe B compounds containing various rare earths R and to R Fe Co B alloys. The results are as follows:1 The sintered Nd Fe B magnet is composed of mainly three phases, the Nd2Fe14B matrix phase plus Nd rich phase and B rich phase ~Nd2Fe7B6 as minor phases.2 Nd2Fe14B has the space group of P42/mnm. The crystal structure of this phase can be described as a layer structure with alternate stacking se quence of a Nd rich layer and a sheet formed only by Fe atoms. The sheet of Fe atoms has a structure similar to the phase found in Fe Cr and Fe Mo systems.3 The Nd rich phase containing more than 95 atoms Nd, 3~5 atoms Fe and a trace of B has fcc structure with a = 0.52 nm. This phase is formed around grain boundaries of the matrix phase. Nd2Fe7B6 phase has an one dimensional incommensurate structure with a = ao and c 8co, based on a tetragonal structure with ao = 0.716 nm and co = 0.391 nm.4 In the as sintered Nd15Fe77B8 alloy periodic strain contrasts are observed along grain boundaries, which disappear after annealing at 870 K. This may be related to the enhancement of the intrinsic coercivity of the sintered mag net by post sintering heat treatment.5 Stable R2Fe14B phases are formed by various rare earths except La. Of all the R2Fe14B com pounds, Nd2Fe14B has the maximum saturation magnetization as high as 1.57 T. Dy and Tb form R2Fe14B phases with the highest anisotropies. Small additions of these elements greatly en hance the coercive force of the Nd2Fe14B base magnet.6 Partial replacement of Fe by Co raises the Curie temperature of the Nd2Fe14B compound, which improves the temperature coe cient of the remanence of the magnet. But the intrinsic co ercive force is decreased by the Co addition.

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Section: Introductionmentioning

confidence: 99%

Permanent magnet materials based on the rare earth-iron-boron tetragonal compounds

Sagawa¹,

Fujimura²,

Yamamoto³

et al. 1984

IEEE Trans. Magn.

748

188

View full text Add to dashboard Cite

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“…In fact, phase 2:14:1 was detected in this way [6,7]. Soon it was discovered that such materials have a coercive force significantly greater than the corresponding massive magnets, including sintered magnets.…”

Section: Nanocrystalline Single-phase Hard Magnetic Materialsmentioning

confidence: 96%

“…Hadjipanais [6,7] and J.J. Croat [8], using the melt spinning technology, obtained a large coercive force on the Pr-Fe-B(Si) and Nd-Fe-B alloys, respectively. The large values of the coercive force in both cases were due to the strongly anisotropic tetragonal phase R 2 Fe 14 B (K = 4.5⋅107 erg/cm 3 ) of the nanoscale value obtained after the crystallization of the spinning flakes [9].…”

Section: Introductionmentioning

confidence: 99%

Nanocrystalline Hard Magnetic Materials

Алымов¹,

Milyaev²,

Yusupov³

et al. 2017

AMT

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The first part of the review covers the results of studies of nanocrystalline single-phase hard magnetic materials, mainly on the basis of compounds of rare earth metals produced by super-fast melt quenching with its subsequent crystallization, mechanical alloying and other rapid solidification techniques such as vapor deposition, etc. Specific features of microstructure, magnetic properties, and mechanisms of magnetic hardening of such alloys are considered. The discussion of magnetic properties of nanocomposite magnets focuses on the exchange interaction of hard magnetic phase with nanoparticles of soft magnetic phase known as the spring interaction effect. The process of magnetic reversal of nanocomposite magnets is discussed. KeywordsCoercive force; hard magnetite alloy; magnetic anisotropy; maximum energy product; nanocomposite material; rare earth compound; residual induction.

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“…0 4 ) 7 . 4 has been taken. For the annealing procedures the samples have been wrapped into Ta foils and sealed in quartz tubes with Ar.…”

Section: Introductionmentioning

confidence: 99%

“…Nevertheless, nanocrystalline magnetic materials of this system have opened a new class of pm materials which are optimally suitable for high-performance polymer bonded magnets. Pms which supply the highest (BII)mnx values at elevated temperatures (beyond which RE2Fe, 4 B is no longer viable) are based on the quintary system Sm 2 (Co,Cu,Fe,Zr)1 7 [5]., With such magnets coercivities as large as I T can be realized even at 500'C which makes them suitable for high temperatures [6,7].…”

Section: Introductionmentioning

confidence: 99%

Nanocrystalline and Nanostructured High-Performance Permanent Magnets

2001

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The rather complex correlation between the microstructure and the magnetic properties is demonstrated for two types of high-quality RE-TM permanent magnets (pins), namely nanocrystalline RE 2 Fe, 4 B (RE = Nd,Pr) and nanostructured Sm 2 (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 RE 2 Fe, 4 B, isotropic bonded pms are fabricated showing maximum energy products in the order of 90 kJ/m 3 . In the case of Sm 2 (Co,Cu,Fe,Zr)1 7 , magnets with excellent hightemperature 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.

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Cobalt-free permanent magnet materials based on iron-rare-earth alloys (invited)

Cited by 160 publications

References 12 publications

Permanent magnet materials based on the rare earth-iron-boron tetragonal compounds

Permanent magnet materials based on the rare earth-iron-boron tetragonal compounds

Nanocrystalline Hard Magnetic Materials

Nanocrystalline and Nanostructured High-Performance Permanent Magnets

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