Hot-working behavior of cast Pr-Fe-B magnets

Shimoda, Tatsuya; Akioka, K.; Kobayashi, Osamu; Yamagami, T.; Ohki, T.; Miyagawa, Matsuo; Yuri, T.

doi:10.1109/20.42535

Cited by 67 publications

(14 citation statements)

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“…During heating, this fact results in unequal contact forces between powder particles for the different texture directions and subsequent aniso tropic sintering. On the other hand, it is known that there exists a grain growth anisotropy during both the solidification [7] and normal grain growth of the Nd 2 Fe 14 B compound [8].…”

Section: Dependence Of the Density Of Sintered Magnets On The Powdementioning

confidence: 99%

Preparation of sintered Nd-Fe-B magnets by pressless process

Попов

Шитов

Gerasimov

et al. 2012

Phys. Metals Metallogr.

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Pressless process used for the preparation of sintered Nd-Fe-B magnets has been studied. The effect of the average particle size D av , filling density ρ f , and powder texturing conditions for obtaining density ρ and desired magnetic hysteretic properties of sintered magnets has been investigated for both traditional technology (TT) and low oxygen technology (LOT). The ρ f magnitude ensuring the optimum relation between the density ρ of sintered magnets and their degree of texture was shown to be 2.5-3.0 and 2.2 g/cm 3 for the TT and LOT, respectively. At lower ρ f magnitudes, no required density of sintered magnets is reached, whereas at higher filling densities, a low level of texture and low remanence are realized. Optimum param eters of pulsed field inducing the high degree of texture in powders have been determined. The following properties were achieved for magnets prepared by pressless LOT: B r ≥ 14.2 kG, H c ≥ 8 kOe, and (BH) max ≥ 47.9 MG Oe.

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Section: Dependence Of the Density Of Sintered Magnets On The Powdementioning

confidence: 99%

Preparation of sintered Nd-Fe-B magnets by pressless process

Попов

Шитов

Gerasimov

et al. 2012

Phys. Metals Metallogr.

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“…Among several addition elements that have been investigated, Cu showed the lowest eutectic temperature when combined with Pr (461˚C) [17]. Grain refinement in cast PrFeBCu-type alloy has been attributed to this element [18] but this has not been observed in the cast or annealed PrFeCoBNbCu alloys (comparison in Figure 1 and Figure 2), although in this investigation Cu had a substantial effect on the pulverized material. At first glance, it might be thought that the eutectic Cu-Pr phase with a low melting point would interfere on the hydrogen process at high temperature (~860˚C).…”

Section: Resultsmentioning

confidence: 66%

Evaluation of Mean Crystallite Size on Magnetic Powder by Scanning Electron Microscopy and Synchrotron Diffractometry

Galego¹,

Serna²,

Faria³

2014

MSA

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This paper presents the results of investigations carried out with Pr-based magnetic powders. The magnetically hard powders were produced from homogenised alloys using a high temperature hydrogen pulverization process. Alloys and powders were investigated by scanning electron microscopy and by energy dispersive X-ray analysis. Mean crystallite size of the pulverized material was estimated using synchrotron powder diffractometry and the Scherrer method. A comparison between these two investigation techniques has been carried out. The effects of copper on the properties of the magnetic powders have been studied. It has been shown that the addition of this alloying element had a marked effect on the microstructure of the powders.

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“…The enhanced magnetic properties evolve from the nanocrystalline structure of the Nd 2 Fe 14 B phase, which promotes magnetic exchange interactions, leading to the lowering of the average magnetic anisotropy [5]. The ribbon powder can further be processed to anisotropic magnet by hot working [6][7][8]. This procedure, developed by General Motors, comprises hot pressing of crushed ribbon into a fully dense isotropic bulk material followed by deformation in the processes, which provide uniaxial stress direction.…”

Section: Introductionmentioning

confidence: 99%