The origin of coercivity decrease in fine grained Nd–Fe–B sintered magnets

Li, W.F.; Ohkubo, T.; Hono, K.; Sagawa, M.

doi:10.1016/j.jmmm.2008.10.032

Cited by 161 publications

(57 citation statements)

References 9 publications

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“…3(a), (c)). This formation of a thin layer of Nd-rich phase along the grain boundary acted as strong pinning sites for domain wall motion [12] and resulted in coercivity enhancement [3]. In addition, the coercivity and remanence of 820 • C-DR treated powders was higher than those of 810 • C-DR treated powders when the Nd content of the alloy was 12.5 at.%.…”

Section: Methodsmentioning

confidence: 99%

Effect Of The Desorption-Recombination Temperature On The Microstructure And Magnetic Properties Of HDDR Processed Nd-Fe-B Powders

Lee

Cha

Liu

et al. 2015

Archives of Metallurgy and Materials

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The effect of the desorption-recombination temperature on the microstructure and magnetic properties of hydrogenationdisproportionation-desorption-recombination (HDDR) processed Nd-Fe-B powders was studied. The Nd x B 6.4 Ga 0.3 Nb 0.2 Fe bal (x=12.5-13.5, at.%) casting alloys were pulverized after homogenizing annealing, and then subjected to HDDR treatment. During the HDDR process, desorption-recombination (DR) reaction was induced at two different temperature, 810 • C and 820 • C. The higher Nd content resulted in enhanced coercivity of the HDDR powder, and which was attributed to the thicker and more uniform Nd-rich phase along grain boundaries. But this uniform Nd-rich phase induced faster grain growth. The remanence of the powder DR-treated at 820 • C is higher than that DR-treated at 810 • C. In addition, it was also confirmed that higher DR temperature is much more effective to improve squareness.

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Section: Methodsmentioning

confidence: 99%

Effect Of The Desorption-Recombination Temperature On The Microstructure And Magnetic Properties Of HDDR Processed Nd-Fe-B Powders

Lee

Cha

Liu

et al. 2015

Archives of Metallurgy and Materials

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“…In order to attain high energy product, it is necessary to enhance the anisotropy field and coercivity. To fabricate magnets with high energy products, the volume fraction of the magnetically hard Nd 2 Fe 14 B compound as matrix phase should be maximum, non-magnetic Nd-rich phase should be located at grain boundaries and magnetically soft α-iron phase should be minimum or completely removed from the structure of sintered parts [9][10][11]. The grain boundary Nd-rich phase is believed that it's strong effect on the coercivity of magnets.…”

Section: Introductionmentioning

confidence: 99%

Effect of Chill Wheel Cooling on Magnetic Properties of Nd15Fe77B8 Alloy Powders Produced by Melt Spinning Method

Öztürk¹

2017

IJMSA

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Abstract:In this study, effect of wheel cooling on magnetic properties of Nd 15 Fe 77 B 8 alloy powders produced by melt spinning method has been investigated. The present method includes the cooling of the copper wheel by externally contacting a coolant block which is cooled by internally circulating freon gas. Within this framework, the effect of wheel temperature on the microstructure and magnetic properties of Nd 15 Fe 77 B 8 powders have been investigated. The temperatures of cooling block and melt spinning wheel were measured as -15°C and -5°C, before experimental run, separately. Produced powders exhibited different morphologies depending on the powder sizes. The smallest size of powders was formed as spherical, ligamental and fiber-like morphologies. As powders get larger, the amount of spherical, ligamental and fiber-like shaped powders decreased and the length of the fibers declined. The microstructural cell sizes for 5 µm and 48 µm size powders were measured as 0.22 µm and 1.23 µm, respectively. The cooling rates of 4 µm, 28 µm and 52 µm sized powders were measured as 5.95 x 10 6 K/s, 0.85 x 10 6 K/s and 0.45 x 10 6 K/s, respectively. The Curie temperature of produced powders was 321.5°C. The coercivity value of melt-spun powders was obtained as 2.842 kOe.

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“…As curvas de desmagnetização dos ímãs produzidos são apresentadas na No caso dos ímãs produzidos com 30 minutos de moagem, este "joelho" pode ter sua origem na heterogeneidade do tamanho de partícula devido ao tempo insuficiente de moagem, produzindo uma distribuição de grãos muito ampla [37][38][39][40].…”

Section: Caracterização Magnéticaunclassified

“…Outro fator é a própria granulometria no pó produzido, que não é adequada à temperatura de sinterização, favorecendo o fenômeno de crescimento anormal de grãos, produzindo também uma distribuição muito ampla de diâmetros de grãos. [37][38][39][40].…”

Section: Caracterização Magnéticaunclassified

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Influência dos parâmetros de processamento na microestrutura e nas propriedades magnéticas de ímãs permanentes de (Nd,Pr)FeB

Fim¹

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The origin of coercivity decrease in fine grained Nd–Fe–B sintered magnets

Cited by 161 publications

References 9 publications

Effect Of The Desorption-Recombination Temperature On The Microstructure And Magnetic Properties Of HDDR Processed Nd-Fe-B Powders

Effect Of The Desorption-Recombination Temperature On The Microstructure And Magnetic Properties Of HDDR Processed Nd-Fe-B Powders

Effect of Chill Wheel Cooling on Magnetic Properties of Nd<sub>15</sub>Fe<sub>77</sub>B<sub>8</sub> Alloy Powders Produced by Melt Spinning Method

Influência dos parâmetros de processamento na microestrutura e nas propriedades magnéticas de ímãs permanentes de (Nd,Pr)FeB

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The origin of coercivity decrease in fine grained Nd–Fe–B sintered magnets

Cited by 161 publications

References 9 publications

Effect Of The Desorption-Recombination Temperature On The Microstructure And Magnetic Properties Of HDDR Processed Nd-Fe-B Powders

Effect Of The Desorption-Recombination Temperature On The Microstructure And Magnetic Properties Of HDDR Processed Nd-Fe-B Powders

Effect of Chill Wheel Cooling on Magnetic Properties of Nd&lt;sub&gt;15&lt;/sub&gt;Fe&lt;sub&gt;77&lt;/sub&gt;B&lt;sub&gt;8&lt;/sub&gt; Alloy Powders Produced by Melt Spinning Method

Influência dos parâmetros de processamento na microestrutura e nas propriedades magnéticas de ímãs permanentes de (Nd,Pr)FeB

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Effect of Chill Wheel Cooling on Magnetic Properties of Nd<sub>15</sub>Fe<sub>77</sub>B<sub>8</sub> Alloy Powders Produced by Melt Spinning Method