Magnetic Properties of Nd–Fe–B–Cr Nanocrystalline Composite Magnets

• Hinomura Toru

  Division of Materials Physics, Department of Physical Science, Graduate School of Engineering Science, Osaka University

• Nasu Saburo

  Division of Materials Physics, Department of Physical Science, Graduate School of Engineering Science, Osaka University

• Kanekiyo Hirokazu

  Fundamental Research Section, Research and Development Division, Sumitomo Special Metals Company, Ltd.

• Uehara Minoru

  Fundamental Research Section, Research and Development Division, Sumitomo Special Metals Company, Ltd.

• Hirosawa Satoshi

  Fundamental Research Section, Research and Development Division, Sumitomo Special Metals Company, Ltd.

Bibliographic Information

Other Title

• Magnetic Properties of Nd Fe B Cr Nanoc
• Magnetic Properties of Nd–Fe–B–Cr Nanocrystalline Composite Magnets

Abstract

Magnetic properties and phase composition of Nd_4.5Fe₇₇B_18.5 exchange-coupled nanocrystalline composite magnet have been investigated as a function of heat treatment by means of differential thermal analysis, magnetization, X-ray diffraction, and ⁵⁷Fe Mössbauer measurements. Cr content dependence of magnetic properties and phase composition of Cr-added Nd_4.5(Fe_1−xCr_x)₇₇B_18.5 has also been investigated. By annealing up to 853 K, Nd_4.5Fe₇₇B_18.5 amorphous ribbon crystallizes in both t-Fe₃B and Nd₂Fe₂₃B₃. These two compounds are soft magnets and the specimen does not have coercivity. Hard magnetic Nd₂Fe₁₄B is precipitated by annealing up to 943 K, and the specimen becomes hard magnetic. Nd_4.5Fe₇₇B_18.5 nanocrystalline composite magnet annealed up to 943 K consists of 10 mole% Nd₂Fe₁₄B and 90 mol% t-Fe₃B, and the small amount of hard magnetic phase results in large coercivity of this material. With increasing Cr content, coercivity of Nd_4.5(Fe_1−xCr_x)₇₇B_18.5 optimally heat-treated ribbon increases, but remanence decreases. In all the specimens, hard magnet Nd₂Fe₁₄B is formed and the amount is found to decrease with increasing Cr content. This is one of the reasons for the reduction of remanence. Soft magnetic phases which crystallize in the specimen changes from t-Fe₃B to Fe₂B and α-Fe depending on Cr content. Hyperfine magnetic field of Fe–B compound decreases as a function of Cr content, while those of Nd₂Fe₁₄B and α-Fe are independent of Cr content. Therefore, Cr atoms mainly exist in Fe–B compound, not in Nd₂Fe₁₄B and α-Fe, and reduce the magnetization and Curie temperature of soft magnetic phases. In addition, the total amount of soft magnetic compounds decreases by the Cr-substitution for Fe. These influences of Cr atoms result in the decrease of the remanence of this material.

Journal

• Materials Transactions, JIM

  Materials Transactions, JIM 38 (12), 1106-1115, 1997

  The Japan Institute of Metals

Keywords

• neodymium-iron-boron magnet
• chromium-added neodymium-iron-boron magnet
• nanocrystalline composite
• <SUP>57</SUP>Fe Mössbauer spectroscopy
• hyperfine magnetic field
• Nd<SUB>2</SUB>Fe<SUB>14</SUB>B
• Nd<SUB>2</SUB>Fe<SUB>23</SUB>B<SUB>3</SUB>
• t-Fe<SUB>3</SUB>B
• Fe<SUB>2</SUB>B

Details

• CRID: 1390282679224008704
• NII Article ID: 130003422501
• NII Article ID: 10002454573
• NII Book ID: AA10699969
• DOI: 10.2320/matertrans1989.38.1106
• COI: 1:CAS:528:DyaK1cXht1ymtLo%3D
• ISSN: 2432471X
• ISSN: 09161821
• NDL BIB ID: 4384542
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I4384542
• Web Site: https://www.jstage.jst.go.jp/article/matertrans1989/38/12/38_12_1106/_pdf
• Text Lang: en
• Data Source:
  • JaLC
  • NDL
  • Crossref
  • CiNii Articles
• Abstract License Flag: Disallowed