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<p>This study investigates sintered magnets produced from alloys of a (Nd<sub>0.75</sub>Dy<sub>0.25</sub>)<sub>32</sub>Fe<sub>66.4–<i>x</i></sub>Co<sub><i>x</i></sub>Cu<sub>0.1</sub>Ga<sub>0.6</sub>B<sub>0.9</sub> system with varying cobalt content. The Curie temperatures of the initial and sintered magnets were determined. A microstructural analysis and x-ray diffraction (XRD) of the magnets were carried out. We optimized the composition of the alloy and the two-stage annealing process. The alloy with an optimal composition of (Nd<sub>0.75</sub>Dy<sub>0.25</sub>)<sub>32</sub>Fe<sub>55.3</sub>Co<sub>11.1</sub>Cu<sub>0.1</sub>Ga<sub>0.6</sub>B<sub>0.9</sub> (wt.%), prepared by a low-oxygen process, exhibited high hysteresis characteristics at room temperature (<i>B</i><sub><i>r</i></sub> = 11.72 kG; <sub>M</sub><i>H</i><sub><i>c</i></sub> = 20.8 kOe; <sub>B</sub><i>H</i><sub><i>c</i></sub> = 11.2 kOe; and (<i>BH</i>)<sub>max</sub> = 32.9 MG ∙ Oe) and a reduced temperature coefficient of magnetic induction, α = |–0.053Ι| %/°C, in the range of 23 – 100°C. The formation of a nonmagnetic Laves phase (Nd, Dy)(Fe, Co, Cu, Ga)<sub>2</sub> along the grain boundaries was identified as the key factor contributing to the increase in coercive force (<i>H</i><sub><i>c</i></sub>) to 20.8 kOe. This enhancement was attributed to improved magnetic insulation between the grains of the main magnetic phase (Nd, Dy)<sub>2</sub>(Fe, Co)<sub>14</sub>B, resulting from the suppressed exchange interaction due to reduced magnetization of the (Nd, Dy)(Fe, Co, Cu, Ga)<sub>2</sub> phase, as the contents of gallium and copper increased.</p>

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High-Coercivity (Nd, Dy) – (Fe, Co) – Cu – Ga – B Magnets with Enhanced Temperature Stability of Magnetic Properties

  • 期刊论文

  • 发表日期：

    2025年9月1日

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  • A. V. Shitov,
  • D. A. Kolodkin,
  • L. A. Stashkova,
  • A. R. Soltus,
  • D. Y. Vasilenko

摘要

This study investigates sintered magnets produced from alloys of a (Nd0.75Dy0.25)32Fe66.4–xCoxCu0.1Ga0.6B0.9 system with varying cobalt content. The Curie temperatures of the initial and sintered magnets were determined. A microstructural analysis and x-ray diffraction (XRD) of the magnets were carried out. We optimized the composition of the alloy and the two-stage annealing process. The alloy with an optimal composition of (Nd0.75Dy0.25)32Fe55.3Co11.1Cu0.1Ga0.6B0.9 (wt.%), prepared by a low-oxygen process, exhibited high hysteresis characteristics at room temperature (Br = 11.72 kG; MHc = 20.8 kOe; BHc = 11.2 kOe; and (BH)max = 32.9 MG ∙ Oe) and a reduced temperature coefficient of magnetic induction, α = |–0.053Ι| %/°C, in the range of 23 – 100°C. The formation of a nonmagnetic Laves phase (Nd, Dy)(Fe, Co, Cu, Ga)2 along the grain boundaries was identified as the key factor contributing to the increase in coercive force (Hc) to 20.8 kOe. This enhancement was attributed to improved magnetic insulation between the grains of the main magnetic phase (Nd, Dy)2(Fe, Co)14B, resulting from the suppressed exchange interaction due to reduced magnetization of the (Nd, Dy)(Fe, Co, Cu, Ga)2 phase, as the contents of gallium and copper increased.