Analysis of magnetization reversal of Nd-Fe-B magnets by dynamic domain observation with a Kerr microscope

• Project/Area Number: 26420311
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Electron device/Electronic equipment
• Research Institution: Kyushu Institute of Technology
• Principal Investigator: Takezawa Masaaki 九州工業大学, 大学院工学研究院, 教授 (20312671)
• Project Period (FY): 2014-04-01 – 2017-03-31
• Project Status: Completed (Fiscal Year 2016)
• Budget Amount: ¥5,200,000 (Direct Cost: ¥4,000,000、Indirect Cost: ¥1,200,000); Fiscal Year 2016: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000); Fiscal Year 2015: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000); Fiscal Year 2014: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000)
• Keywords: 磁区観察 / 磁区構造 / 磁気Kerr効果 / ハード磁性材料 / ネオジム磁石 / 減磁過程

Outline of Final Research Achievements

We observed the demagnetization behavior of Nd-Fe-B magnets by observing their magnetic domains with a high-resolution and dynamic domain observation system using Kerr effect microscope. The relation between the domain configuration and microstructure observed by a scanning electron microscope was investigated. The reversal domains nucleated from the impurity site and a-Fe enriched point that deteriorate hard magnetic properties. Moreover, magnetic interaction among the grains beyond the grain boundaries caused simultaneous magnetization reversal. The large magnetization-reversal clusters produced the low-coercivity, and also reduced the squareness of the magnet.

Research Products

• [Journal Article] The high squareness Sm-Co magnet having Hcb=10.6 kOe at 150°C (2017)
  • Author(s): H. Machida, T. Fujiwara, R. Kamada, Y. Morimoto, and M. Takezawa
  • Journal Title: AIP Advances Volume: 7 Issue: 5
  • DOI: 10.1063/1.4976334
  • Peer Reviewed / Open Access
• [Journal Article] Analysis of Thermal Demagnetization Behavior of Nd-Fe-B Sintered Magnets Using Magnetic Domain Observation (2016)
  • Author(s): M. Takezawa, S. Ikeda, Y. Morimoto and H. Kabashima
  • Journal Title: AIP Advances Volume: 6 Issue: 5 Pages: 056021-056021
  • DOI: 10.1063/1.4944402
  • NAID: 120005716906
  • Peer Reviewed / Open Access
• [Journal Article] Relationship between Microstructure and Magnetic Domain Structure of Nd-Fe-B Melt-Spun Ribbon Magnets (2015)
  • Author(s): M. Takezawa, H. Taneda and Y. Morimoto
  • Journal Title: Frontiers of Materials Science Volume: 9 Issue: 2 Pages: 206-210
  • DOI: 10.1007/s11706-015-0297-5
  • NAID: 120005941591
  • Peer Reviewed / Open Access
• [Journal Article] Nd-Fe-B系焼結磁石の高温下における減磁過程の磁区観察 (2015)
  • Author(s): 竹澤昌晃、荻本紘史、森本祐治
  • Journal Title: 粉体および粉末冶金 Volume: 2 Pages: 67-71
  • NAID: 130005060879
  • Peer Reviewed
• [Presentation] Nd-Fe-B 系焼結磁石における隣接粒子間方位差と磁化反転の関係 (2017)
  • Author(s): 槙 智仁, 打越 凌, 石井 倫太郎, 西内 武司, 竹澤 昌晃
  • Organizer: 日本金属学会春期大会
  • Place of Presentation: 首都大学東京
  • Year and Date: 2017-03-15
• [Presentation] Nd-Fe-B系焼結磁石における高温中における圧縮応力による磁区構造変化 (2016)
  • Author(s): 福島 啓子, 竹澤 昌晃, 森本 祐治, 中野 善和, 松本 紀久
  • Organizer: 電気学会マグネティックス研究会
  • Place of Presentation: 慶応大学
  • Year and Date: 2016-12-11
• [Presentation] Nd-Fe-B異方性HDDR磁粉の磁区構造と減磁過程 (2016)
  • Author(s): 永石 知也, 竹澤 昌晃, 榛葉 和晃, 三嶋 千里, 御手洗 浩成
  • Organizer: 電気学会マグネティックス研究会
  • Place of Presentation: 日本電気計器検定所(東京都港区)
  • Year and Date: 2016-11-28
• [Presentation] The High Squareness Sm-Co Magnet Having Hcb=10.6kOe at 150°C (2016)
  • Author(s): H. Machida, T. Fujiwara, R. Kamada, Y. Morimoto, and M. Takezawa
  • Organizer: 61th Annual Conference on Magnetism and Magnetic Materials
  • Place of Presentation: New Orleans, USA
  • Year and Date: 2016-10-31
  • Int'l Joint Research
• [Presentation] Magnetic Domain Observation on Demagnetization of Nd-Fe-B Sintered Magnets under Compressive Stress and Elevated Temperatures (2016)
  • Author(s): M. Takezawa, K. Fukushima, Y. Morimoto, and Y. Nakano
  • Organizer: 61th Annual Conference on Magnetism and Magnetic Materials
  • Place of Presentation: New Orleans, USA
  • Year and Date: 2016-10-31
  • Int'l Joint Research
• [Presentation] 磁区観察を用いたNd-Fe-B系焼結磁石の熱減磁解析 (2016)
  • Author(s): 池田 壮一郎, 森本 祐治, 竹澤 昌晃, 椛嶌 寿行
  • Organizer: 平成28年 電気学会基礎・材料・共通部門大会
  • Place of Presentation: 九州工業大学
  • Year and Date: 2016-09-06
• [Presentation] Nd-Fe-B系焼結磁石の圧縮応力による磁区構造変化 (2016)
  • Author(s): 竹澤 昌晃, 森本 祐治, 江島 潤, 中野 善和, 荒木 健
  • Organizer: 平成28年 電気学会基礎・材料・共通部門大会
  • Place of Presentation: 九州工業大学
  • Year and Date: 2016-09-06
• [Presentation] Influence of misorientation angle between easy-axes of adjacent grains on magnetic domain propagation in Nd-Fe-B sintered magnet (2016)
  • Author(s): T. Maki, R. Uchikoshi, R. Ishii, T. Nishiuchi, and M. Takezawa
  • Organizer: 24th International Workshop on Rare-Earth and Future Permanent Magnets and their Applications
  • Place of Presentation: Darmstadt, Germany
  • Year and Date: 2016-08-28
  • Int'l Joint Research
• [Presentation] Nd-Fe-B系焼結磁石の配向度と磁区構造の関係 (2016)
  • Author(s): 打越 凌, 池田 尊穂, 竹澤 昌晃, 槙 智仁, 石井 倫太郎, 西内 武司, 松浦 裕
  • Organizer: 電気学会マグネティックス研究会
  • Place of Presentation: 豊橋技術科学大学
  • Year and Date: 2016-08-09
• [Presentation] Nd-Fe-B 系焼結磁石における熱と圧縮応力による磁区構造変化 (2016)
  • Author(s): 竹澤 昌晃, 福島 啓子, 森本 祐治, 中野 善和
  • Organizer: 平成28年 電気学会全国大会
  • Place of Presentation: 東北大学
  • Year and Date: 2016-03-16
• [Presentation] Analysis of Thermal Demagnetization Behavior of Nd-Fe-B Sintered Magnets Using Magnetic Domain Observation (2016)
  • Author(s): M. Takezawa, S. Ikeda, Y. Morimoto and H. Kabashima
  • Organizer: The 13th Joint MMM/Intermag Conference
  • Place of Presentation: San Diego
  • Year and Date: 2016-01-12
  • Int'l Joint Research
• [Presentation] 磁区観察によるNd-Fe-B系焼結磁石の熱減磁解析 (2015)
  • Author(s): 池田 壮一郎, 竹澤 昌晃, 森本 祐治, 椛嶌 寿行
  • Organizer: 電気学会マグネティックス研究会
  • Place of Presentation: 日本電気計器検定所
  • Year and Date: 2015-12-01
• [Presentation] In-situ Magnetic Domain Observation of Nd-Fe-B Permanent Magnet with a Kerr Microscope (2015)
  • Author(s): M. Takezawa, H. Ogimoto, H. Taneda and Y. Morimoto
  • Organizer: 14th International Union of Materials Research Societies- International Conference on Advanced Materials (IUMRS-ICAM2015)
  • Place of Presentation: Jeju, Korea
  • Year and Date: 2015-10-29
  • Int'l Joint Research / Invited
• [Presentation] Nd-Fe-B 系焼結磁石の磁区構造と結晶組織の関係 (2015)
  • Author(s): 永石 知也, 森本 祐治, 竹澤 昌晃
  • Organizer: 第39回 日本磁気学会学術講演会
  • Place of Presentation: 名古屋大学
  • Year and Date: 2015-09-10
• [Presentation] Relationship between Microstructure and Magnetic Domain structure of Nd-Fe-B Melt-spun Ribbon Magnets (2015)
  • Author(s): M. Takezawa, H. Taneda, and Y. Morimoto
  • Organizer: EMN (Energy Materials Nanotechnology) Meeting on Photovoltaics
  • Place of Presentation: Orlando, FL, USA
  • Year and Date: 2015-01-12 – 2015-01-15
  • Invited
• [Presentation] Relationship between microstructure and magnetic domain structure of anisotropic melt-spun Nd－Fe－B ribbons (2014)
  • Author(s): M. Takezawa, H. Taneda, and Y. Morimoto
  • Organizer: 59th Annual Conference on Magnetism and Magnetic Materials
  • Place of Presentation: Honolulu, Hawai, USA
  • Year and Date: 2014-11-03 – 2014-11-07
• [Presentation] Nd-Fe-B急冷薄帯磁石の結晶組織と硬質磁気特性 (2014)
  • Author(s): 竹澤 昌晃, 種子田 大幸, 森本 祐治
  • Organizer: 平成26年 電気学会 基礎・材料・共通部門大会
  • Place of Presentation: 信州大学
  • Year and Date: 2014-08-21 – 2014-08-22
• [Presentation] Magnetic Domain Observation of Nd-Fe-B Sintered Magnets with A Kerr Microscope (2014)
  • Author(s): M. Takezawa, H. Ogimoto and Y. Morimoto
  • Organizer: The Moscow International Symposium on Magnetism (MISM) 2014
  • Place of Presentation: Moscow, Russia
  • Year and Date: 2014-06-29 – 2014-07-03
  • Invited
• [Presentation] Nd-Fe-B系焼結磁石の高温下における減磁過程の磁区観察 (2014)
  • Author(s): 竹澤 昌晃, 荻本 紘史, 森本 祐治
  • Organizer: 粉体粉末治金協会 平成26年度春季大会
  • Place of Presentation: 早稲田大学
  • Year and Date: 2014-06-03 – 2014-06-05
  • Invited