Influence of desorption recombination temperatures on microstructure and coercivity of HDDR-processed anisotropic Nd-Fe-B magnet powders

Rina Takizawa, Hiroshi Akamine, Masaru Itakura, Minoru Nishida, Nobuhiro Katayama, Koichiro Morimoto

Research output: Contribution to journalArticle

Abstract

In the hydrogenation decomposition desorption recombination(HDDR)processed Nd Fe Co B Al Ga Zr magnet powders, influence of the desorption recombination(DR)temperatures on the microstructures was investigated by high resolution scanning electron microscopy and scanning transmission electron microscopy. By applying the DR treatment under high vacuum(DR Step 2)at relative low temperatures about 973 K, we can obtain the excellent texture in which the average size of Nd2Fe14B grains is refined to about 240 nm and the grain boundary(GB)phase is uniformly dispersed around the Nd2Fe14B grains. In the GB phase, furthermore, the Nd composition increases and the(Fe, Co)composition decreases drastically with decreasing the DR temperatures, and then Nd rich GB phase with more than 65 at.%Nd can be formed at 973 K. At 973 K, however, the region with unformed GB phase is remained about 10% of the specimen, which leads to deterioration of the coercivity. It was found that the gently DR treatment is very effective not only for increasing the coercivity but also for improving the squareness in demagnetization curve.

Original languageEnglish
Pages (from-to)121-124
Number of pages4
JournalNippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals
Volume82
Issue number4
DOIs
Publication statusPublished - Jan 1 2018

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Coercive force
Powders
Hydrogenation
hydrogenation
coercivity
Magnets
Desorption
magnets
desorption
Decomposition
decomposition
microstructure
Microstructure
Grain boundaries
grain boundaries
Temperature
temperature
Demagnetization
Scanning electron microscopy
scanning electron microscopy

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Mechanics of Materials
  • Metals and Alloys
  • Materials Chemistry

Cite this

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title = "Influence of desorption recombination temperatures on microstructure and coercivity of HDDR-processed anisotropic Nd-Fe-B magnet powders",
abstract = "In the hydrogenation decomposition desorption recombination(HDDR)processed Nd Fe Co B Al Ga Zr magnet powders, influence of the desorption recombination(DR)temperatures on the microstructures was investigated by high resolution scanning electron microscopy and scanning transmission electron microscopy. By applying the DR treatment under high vacuum(DR Step 2)at relative low temperatures about 973 K, we can obtain the excellent texture in which the average size of Nd2Fe14B grains is refined to about 240 nm and the grain boundary(GB)phase is uniformly dispersed around the Nd2Fe14B grains. In the GB phase, furthermore, the Nd composition increases and the(Fe, Co)composition decreases drastically with decreasing the DR temperatures, and then Nd rich GB phase with more than 65 at.{\%}Nd can be formed at 973 K. At 973 K, however, the region with unformed GB phase is remained about 10{\%} of the specimen, which leads to deterioration of the coercivity. It was found that the gently DR treatment is very effective not only for increasing the coercivity but also for improving the squareness in demagnetization curve.",
author = "Rina Takizawa and Hiroshi Akamine and Masaru Itakura and Minoru Nishida and Nobuhiro Katayama and Koichiro Morimoto",
year = "2018",
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doi = "10.2320/jinstmet.J2017061",
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AU - Takizawa, Rina

AU - Akamine, Hiroshi

AU - Itakura, Masaru

AU - Nishida, Minoru

AU - Katayama, Nobuhiro

AU - Morimoto, Koichiro

PY - 2018/1/1

Y1 - 2018/1/1

N2 - In the hydrogenation decomposition desorption recombination(HDDR)processed Nd Fe Co B Al Ga Zr magnet powders, influence of the desorption recombination(DR)temperatures on the microstructures was investigated by high resolution scanning electron microscopy and scanning transmission electron microscopy. By applying the DR treatment under high vacuum(DR Step 2)at relative low temperatures about 973 K, we can obtain the excellent texture in which the average size of Nd2Fe14B grains is refined to about 240 nm and the grain boundary(GB)phase is uniformly dispersed around the Nd2Fe14B grains. In the GB phase, furthermore, the Nd composition increases and the(Fe, Co)composition decreases drastically with decreasing the DR temperatures, and then Nd rich GB phase with more than 65 at.%Nd can be formed at 973 K. At 973 K, however, the region with unformed GB phase is remained about 10% of the specimen, which leads to deterioration of the coercivity. It was found that the gently DR treatment is very effective not only for increasing the coercivity but also for improving the squareness in demagnetization curve.

AB - In the hydrogenation decomposition desorption recombination(HDDR)processed Nd Fe Co B Al Ga Zr magnet powders, influence of the desorption recombination(DR)temperatures on the microstructures was investigated by high resolution scanning electron microscopy and scanning transmission electron microscopy. By applying the DR treatment under high vacuum(DR Step 2)at relative low temperatures about 973 K, we can obtain the excellent texture in which the average size of Nd2Fe14B grains is refined to about 240 nm and the grain boundary(GB)phase is uniformly dispersed around the Nd2Fe14B grains. In the GB phase, furthermore, the Nd composition increases and the(Fe, Co)composition decreases drastically with decreasing the DR temperatures, and then Nd rich GB phase with more than 65 at.%Nd can be formed at 973 K. At 973 K, however, the region with unformed GB phase is remained about 10% of the specimen, which leads to deterioration of the coercivity. It was found that the gently DR treatment is very effective not only for increasing the coercivity but also for improving the squareness in demagnetization curve.

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