中国物理B ›› 2016, Vol. 25 ›› Issue (11): 117504-117504.doi: 10.1088/1674-1056/25/11/117504

• CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES • 上一篇    下一篇

Improvement in coercivity,thermal stability,and corrosion resistance of sintered Nd-Fe-B magnets with Dy80Ga20 intergranular addition

Beibei Zhou(周贝贝), Xiangbin Li(李向斌), Xuejing Cao(曹学静), Gaolin Yan(严高林), Aru Yan(闫阿儒)   

  1. 1 School of Physics and Technology, Wuhan university, Wuhan 430072, China;
    2 Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China
  • 收稿日期:2016-05-19 修回日期:2016-08-09 出版日期:2016-11-05 发布日期:2016-11-05
  • 通讯作者: Gaolin Yan E-mail:gaolinyan@whu.edu.cn
  • 基金资助:
    Project supported by the Ministry of Science and Technology of China (Grant Nos. 2014DFB50130 and 2011CB612304) and the National Natural Science Foundation of China (Grant Nos. 51172168 and 51072139).

Improvement in coercivity,thermal stability,and corrosion resistance of sintered Nd-Fe-B magnets with Dy80Ga20 intergranular addition

Beibei Zhou(周贝贝)1, Xiangbin Li(李向斌)1, Xuejing Cao(曹学静)1, Gaolin Yan(严高林)1, Aru Yan(闫阿儒)2   

  1. 1 School of Physics and Technology, Wuhan university, Wuhan 430072, China;
    2 Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China
  • Received:2016-05-19 Revised:2016-08-09 Online:2016-11-05 Published:2016-11-05
  • Contact: Gaolin Yan E-mail:gaolinyan@whu.edu.cn
  • Supported by:
    Project supported by the Ministry of Science and Technology of China (Grant Nos. 2014DFB50130 and 2011CB612304) and the National Natural Science Foundation of China (Grant Nos. 51172168 and 51072139).

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摘要： To investigate the coercivity, corrosion resistance, and thermal stability of Nd-Fe-B magnets, their properties were investigated at room and high temperature before and after doping with Dy80Ga20 (at.%) powder. The coercivity of the magnets increased from the undoped value of 12.72 kOe to a doped value of 21.44 kOe. A micro-structural analysis indicates that a well-developed core-shell structure forms in the magnets doped with Dy80Ga20 powder. The improvement in magnetic properties is believed to be related to the refined and uniform matrix grains, continuous grain boundaries, and a hardened (Nd, Dy)2Fe14B shell surrounding the matrix grains. Additionally, the doped magnets exhibit an obvious improvement in thermal stability. For the magnets with added Dy80Ga20 powder, the temperature coefficients of remanence (α) and coercivity (β) increased to -0.106%℃-1 and -0.60%℃-1 over the range 20-100℃, compared to temperature coefficients of -0.117%℃-1 (α) and -0.74%℃-1 (β) in the regular magnets without Dy80Ga20 powder. The irreversible loss of magnetic flux (Hirr) was investigated at different temperatures. After being exposed to 150℃ for 2 h, the Hirr of magnets with 4 wt.% Dy80Ga20 decreased by ~95% compared to that of the undoped magnets. The enhanced temperature coefficients and Hirr indicate improved thermal stability in the doped Nd-Fe-B magnets. The intergranular addition of Dy80Ga20 also improved the corrosion resistance of the magnets because of the enhanced intergranular phase. In a corrosive atmosphere for 96 h, the mass loss of the sintered magnets with 4 wt.% Dy80Ga20 was 2.68 mg/cm2, less than 10% of that suffered by the undoped magnets (28.1 mg/cm2).

关键词: Nd-Fe-B permanent magnet, magnetic property, thermal stability, corrosion resistance

Abstract: To investigate the coercivity, corrosion resistance, and thermal stability of Nd-Fe-B magnets, their properties were investigated at room and high temperature before and after doping with Dy80Ga20 (at.%) powder. The coercivity of the magnets increased from the undoped value of 12.72 kOe to a doped value of 21.44 kOe. A micro-structural analysis indicates that a well-developed core-shell structure forms in the magnets doped with Dy80Ga20 powder. The improvement in magnetic properties is believed to be related to the refined and uniform matrix grains, continuous grain boundaries, and a hardened (Nd, Dy)2Fe14B shell surrounding the matrix grains. Additionally, the doped magnets exhibit an obvious improvement in thermal stability. For the magnets with added Dy80Ga20 powder, the temperature coefficients of remanence (α) and coercivity (β) increased to -0.106%℃-1 and -0.60%℃-1 over the range 20-100℃, compared to temperature coefficients of -0.117%℃-1 (α) and -0.74%℃-1 (β) in the regular magnets without Dy80Ga20 powder. The irreversible loss of magnetic flux (Hirr) was investigated at different temperatures. After being exposed to 150℃ for 2 h, the Hirr of magnets with 4 wt.% Dy80Ga20 decreased by ~95% compared to that of the undoped magnets. The enhanced temperature coefficients and Hirr indicate improved thermal stability in the doped Nd-Fe-B magnets. The intergranular addition of Dy80Ga20 also improved the corrosion resistance of the magnets because of the enhanced intergranular phase. In a corrosive atmosphere for 96 h, the mass loss of the sintered magnets with 4 wt.% Dy80Ga20 was 2.68 mg/cm2, less than 10% of that suffered by the undoped magnets (28.1 mg/cm2).

Key words: Nd-Fe-B permanent magnet, magnetic property, thermal stability, corrosion resistance

中图分类号:  (Permanent magnets)

  • 75.50.Ww
75.30.-m (Intrinsic properties of magnetically ordered materials) 65.40.-b (Thermal properties of crystalline solids) 82.45.Bb (Corrosion and passivation)