Magnetic anisotropy and crystallographic alignment in Fe and NdH2 during d -HDDR process of Nd-Fe-B-Ga-Nb powders

Takashi Horikawa; Masao Yamazaki; Chisato Mishima; Masashi Matsuura; Satoshi Sugimoto

doi:10.1063/1.5079953

Magnetic anisotropy and crystallographic alignment in Fe and NdH₂ during d -HDDR process of Nd-Fe-B-Ga-Nb powders

Takashi Horikawa, Masao Yamazaki, Chisato Mishima, Masashi Matsuura, Satoshi Sugimoto

ENG - Materials Science

Research output: Contribution to journal › Article › peer-review

6 Citations (Scopus)

Abstract

Hydrogen disproportionation (HD) treatments at 820°C for 10 h with different hydrogen pressures (P_HD) were performed for Nd-Fe-B-Ga-Nb magnetic powder to clarify the relationship between the structural differences and resultant magnetic anisotropy as a function of P_HD during dynamic hydrogen disproportionation desorption recombination. When P_HD was 30 kPa, the anisotropy was the highest after recombination, and coarsened lamellar and spherical structures comprising Fe and NdH₂ were observed after HD treatment. In the coarse lamellar structures, the crystallographic orientations of adjacent Fe and NdH₂ grains were the same. The diameters of such regions were approximately 1100 nm, and their total area fraction was approximately 70% of the Fe and NdH₂ phases. In contrast, when P_HD was 100 kPa at which the anisotropy was lower, the sample consisted of mainly spherical grains, and the total area fraction of the regions where adjacent Fe and NdH₂ grains exhibited the same crystallographic orientations was small (25%). This result indicates that the presence of coarsened lamellar comprising crystallographically aligned Fe and NdH₂ grains contributed significantly to the induction of anisotropy after recombination.

Original language	English
Article number	035244
Journal	AIP Advances
Volume	9
Issue number	3
DOIs	https://doi.org/10.1063/1.5079953
Publication status	Published - 2019 Mar 1

ASJC Scopus subject areas

Physics and Astronomy(all)

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@article{e635621f99e5476d997c8c1edbafd9ef,

title = "Magnetic anisotropy and crystallographic alignment in Fe and NdH2 during d -HDDR process of Nd-Fe-B-Ga-Nb powders",

abstract = "Hydrogen disproportionation (HD) treatments at 820°C for 10 h with different hydrogen pressures (PHD) were performed for Nd-Fe-B-Ga-Nb magnetic powder to clarify the relationship between the structural differences and resultant magnetic anisotropy as a function of PHD during dynamic hydrogen disproportionation desorption recombination. When PHD was 30 kPa, the anisotropy was the highest after recombination, and coarsened lamellar and spherical structures comprising Fe and NdH2 were observed after HD treatment. In the coarse lamellar structures, the crystallographic orientations of adjacent Fe and NdH2 grains were the same. The diameters of such regions were approximately 1100 nm, and their total area fraction was approximately 70% of the Fe and NdH2 phases. In contrast, when PHD was 100 kPa at which the anisotropy was lower, the sample consisted of mainly spherical grains, and the total area fraction of the regions where adjacent Fe and NdH2 grains exhibited the same crystallographic orientations was small (25%). This result indicates that the presence of coarsened lamellar comprising crystallographically aligned Fe and NdH2 grains contributed significantly to the induction of anisotropy after recombination.",

author = "Takashi Horikawa and Masao Yamazaki and Chisato Mishima and Masashi Matsuura and Satoshi Sugimoto",

note = "Funding Information: This work was partially supported by the Future Pioneering Projects/Development of Magnetic Material Technology for High-Efficiency Motors from NEDO and the Elemental Strategy Initiative Center for Magnetic Materials (ESICMM) under the outsourcing project of MEXT, Japan. Publisher Copyright: {\textcopyright} 2019 Author(s).",

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doi = "10.1063/1.5079953",

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T1 - Magnetic anisotropy and crystallographic alignment in Fe and NdH2 during d -HDDR process of Nd-Fe-B-Ga-Nb powders

AU - Horikawa, Takashi

AU - Yamazaki, Masao

AU - Mishima, Chisato

AU - Matsuura, Masashi

AU - Sugimoto, Satoshi

N1 - Funding Information: This work was partially supported by the Future Pioneering Projects/Development of Magnetic Material Technology for High-Efficiency Motors from NEDO and the Elemental Strategy Initiative Center for Magnetic Materials (ESICMM) under the outsourcing project of MEXT, Japan. Publisher Copyright: © 2019 Author(s).

PY - 2019/3/1

Y1 - 2019/3/1

N2 - Hydrogen disproportionation (HD) treatments at 820°C for 10 h with different hydrogen pressures (PHD) were performed for Nd-Fe-B-Ga-Nb magnetic powder to clarify the relationship between the structural differences and resultant magnetic anisotropy as a function of PHD during dynamic hydrogen disproportionation desorption recombination. When PHD was 30 kPa, the anisotropy was the highest after recombination, and coarsened lamellar and spherical structures comprising Fe and NdH2 were observed after HD treatment. In the coarse lamellar structures, the crystallographic orientations of adjacent Fe and NdH2 grains were the same. The diameters of such regions were approximately 1100 nm, and their total area fraction was approximately 70% of the Fe and NdH2 phases. In contrast, when PHD was 100 kPa at which the anisotropy was lower, the sample consisted of mainly spherical grains, and the total area fraction of the regions where adjacent Fe and NdH2 grains exhibited the same crystallographic orientations was small (25%). This result indicates that the presence of coarsened lamellar comprising crystallographically aligned Fe and NdH2 grains contributed significantly to the induction of anisotropy after recombination.

AB - Hydrogen disproportionation (HD) treatments at 820°C for 10 h with different hydrogen pressures (PHD) were performed for Nd-Fe-B-Ga-Nb magnetic powder to clarify the relationship between the structural differences and resultant magnetic anisotropy as a function of PHD during dynamic hydrogen disproportionation desorption recombination. When PHD was 30 kPa, the anisotropy was the highest after recombination, and coarsened lamellar and spherical structures comprising Fe and NdH2 were observed after HD treatment. In the coarse lamellar structures, the crystallographic orientations of adjacent Fe and NdH2 grains were the same. The diameters of such regions were approximately 1100 nm, and their total area fraction was approximately 70% of the Fe and NdH2 phases. In contrast, when PHD was 100 kPa at which the anisotropy was lower, the sample consisted of mainly spherical grains, and the total area fraction of the regions where adjacent Fe and NdH2 grains exhibited the same crystallographic orientations was small (25%). This result indicates that the presence of coarsened lamellar comprising crystallographically aligned Fe and NdH2 grains contributed significantly to the induction of anisotropy after recombination.

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Magnetic anisotropy and crystallographic alignment in Fe and NdH₂ during d -HDDR process of Nd-Fe-B-Ga-Nb powders

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