The Effect of Mechanical Grinding on the Magnetic Properties of Nd-Fe-B Ingots

분쇄처리가 Nd-Fe-B계 ingot의 자기적 특성에 미치는 영향

  • Hwang, Yeon (Minerals Utilization & Materials Division, Korea Institute of Geology, Mining & Materials) ;
  • Kim, Taek-Soo (Minerals Utilization & Materials Division, Korea Institute of Geology, Mining & Materials) ;
  • Lee, Hyo-Sook (Minerals Utilization & Materials Division, Korea Institute of Geology, Mining & Materials)
  • 황연 (한국자원연구소 활용연구부) ;
  • 김택수 (한국자원연구소 활용연구부) ;
  • 이효숙 (한국자원연구소 활용연구부)
  • Published : 1998.11.01

Abstract

Mechanical grinding and subsequent annealing were applied to the $Nd_5Pr_7Fe_{82}B_6$ and $Nd_{12}Fe_{82}B_6$ ingots, and the crystal structure and magnetic properties were investigated. After 330 hours milling, the particles with $2~3\mu\textrm{m}$average size were identified to be composed of very fine crystallites judging from the x-ray diffraction patterns. The intrinsic coercivity of 18.36 ~ 18.79 kOe and the maximum energy product of 8.32-8.38 MGOe were obtained by the annealing of the milled powders at $600^{\circ}C$ for 2 hours. Annealing at a higher temperature resulted in the improved magnetic properties. However it was revealed that the control of the micro-crystallites formed during the grinding process was more important to get an optimized magnetic properties than the annealing condition.

$Nd_5Pr_7Fe_{82}B_6$$Nd_{12}Fe_{82}B_6$ 조성의 1차 용유된 ingot에 대하여 기계적 분쇄처리 및 열처리를 행하고 결정구조 및 자기적 특성을 측정하였다. Ar 분위기 하에서 330시간 분쇄처리한 결과 $2~3\mu\textrm{m}$크기의 입자가 얻어졌으며, x-선 회절도로부터 각 입자는 미세한 결정립으로 구성되어 있음을 알았다. 330시간 분쇄처리된 분말을 $600^{\circ}C$에서 2시간 열처리함으로써 항자계가 18.36-18.79kOe, 최대에너지적이 8.32-8.38 MGOe인 자기적 특성을 얻었다. 열처리 온도가 높아지면 자기적 특성이 향상되었으나, 기계적 분쇄처리에 의한 ingot의 미세결정화 과정이 최적의 자기적 특성을 얻는데 더욱 중요하였다.

Keywords

References

  1. J. Appl. Phys. v.55 M.Sagawa;S.Fujimura;N.Togawa;H.Yamamoto;Y.Matsuura
  2. J. Appl. Phys. v.55 J.J.Croat;J.F.Herbst;R.W.Lee;F.E.Pinkerton
  3. J. Appl. Phys. v.57 N.C.Koon;B.N.Das;M.Rubinstein;J.Tyson
  4. J. Appl. Phys. v.57 C.Abache;H.Oesterreicher
  5. IEEE Trans. Magn. v.MAG-21 R.W.Lee;E.G.Brewer;N.A.Schaffel
  6. J. Appl. Phys. v.62 J.Wecker;L.Schultz
  7. Appl. Phys. Lett. v.43 C.C.Koch;O.B.Cavin;C.G.McKamey;J.O.Scabrough
  8. J. Appl. Phys. v.72 T.Harada;T.Kuji
  9. 日本應用磁氣學會誌 v.19 T.Kato;T.Ohno;T.Huruya
  10. J. Mater. Sci. Lett. v.8 T.Nakamura;A.Inoue;K,Matsuki;T.Masumoto
  11. Mater. Lett. v.4 H.H.Stadelmajer;N.C.Liu
  12. Appl. Phys. Lett. v.48 K.Gudimetta;C.N.Christodoulou;G.C.Hadijipanayis
  13. Mater. Sci. Forum v.88-90 A.Calka;J.S.Williams
  14. Mater. Sci. Eng. v.A134 A.Calka;A.P.Radlinski
  15. J. Magn. Magn. Mater v.54-57 R.K.Mishra
  16. J. Appl. Phys. v.67 T.Harada;T.Ando;R.C.O'Handley;N.J.Grant