Hostname: page-component-76fb5796d-vvkck Total loading time: 0 Render date: 2024-04-26T06:22:36.098Z Has data issue: false hasContentIssue false
  • English
  • Français

Initial Magnetization Behavior of Rapidly Quenched Neodymium-Iron-Boron Magnets

Published online by Cambridge University Press:  25 February 2011

F. E. Pinkerton
F. E. Pinkerton*
Affiliation:
Physics Department, General Motors Research Laboratories, Warren, MI 48090-9055
Get access

Abstract

Initial magnetization and demagnetization data are reported for three forms of rapidly solidified Nd-Fe-B permanent magnet materials: melt-spun ribbons, hot pressed magnets, and die upset magnets. In all three materials the results are consistent with domain wall pinning at grain boundary phases as the coercivity mechanism. Optimally quenched ribbons are comprised of randomly oriented single domain Nd2Fe14B grains, and both initial magnetization and demagnetization are controlled by strong domain wall pinning at grain boundaries. Maximum coercivity is accompanied by a low initial permeability. Coercivity is reduced in overquenched ribbons by partial retention of a magnetically soft amorphous or very finely crystalline microstructure. Coercivity decreases in underquenched ribbons because wall pinning weakens as the grain size increases above optimum. Correlation of magnetization and demagnetization behaviors suggests that maximum coercivity in ribbons is largely determined by the resistance to domain wall formation in grains smaller than the single domain particle limit. Grain size is much less important in the aligned die upset magnets. Domain walls are initially free to move until they become strongly pinned at grain edges, and complete magnetization requires an applied field greater than the coercive field. Hot pressed magnets show a mixture of ribbon and die upset behavior.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 96: Symposium F – High Performance Permanent Magnet Materials , 1987 , 65
Copyright
Copyright © Materials Research Society 1987

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

10. REFERENCES

1. Herbst, J. F., Croat, J. J., Pinkerton, F. E., and Yelon, W. B., Phys. Rev. B 29, 4176 (1984).Google Scholar
2. Livingston, J. D., in Proceedings of the 8th International Workshop on Rare-Earth Magnets and Their Applications, edited by Strnat, K. J. (University of Dayton, Magnetics, KL-365, Dayton, Ohio 45469), pp. 423–440.Google Scholar
3. Herbst, J. F., Lee, R. W., and Pinkerton, F. E., Annu. Rev. Mater. Sci. 16, 467 (1986).Google Scholar
4. Croat, J. J., Herbst, J. F., Lee, R. W., and Pinkerton, F. E., J. Appl. Phys. 55, 2078 (1984).Google Scholar
5. Sagawa, M., Fujimura, S., Togawa, N., Yamamoto, H., and Matsuura, Y., J. Appl. Phys. 55, 2083 (1984).Google Scholar
6. Lee, R. W., Appl. Phys. Lett. 46, 790 (1985); R. W. Lee, E. G. Brewer, and N. A. Schaffel, IEEE Trans. Mag. MAG-21, 1958 (1985).Google Scholar
7. Pinkerton, F. E., IEEE Trans. Mag. MAG–22, 922 (1986).Google Scholar
8. Pinkerton, F. E. and VanWingerden, D. J., J. Appl. Phys. 60, 3685 (1986).Google Scholar
9. Mishra, R. K., J. Mag. Magn. Mater. 54–57, 450 (1986).Google Scholar
10. Stoner, E. C. and Wohlfarth, E. P., Philos. Trans. Roy. Soc. London A240, 599 (1948).Google Scholar
11. Pinkerton, F. E. (unpublished).Google Scholar
12. Mishra, R. K. and Lee, R. W., Appl. Phys. Lett. 48, 733 (1986).Google Scholar
13. Livingston, J. D., J. Appl. Phys. 57, 4137 (1985).Google Scholar
14. Hilscher, G., Grössinger, R., Heisz, S., Sassik, H., and Wiesinger, G., J. Mag. Magn. Mater. 54–57, 577 (1986).Google Scholar
15. Durst, K.-D. and Kronmfiller, H., in Proceedings of the 4th International Symposium on Magnetic Anisotropy and Coercivity in Rare Earth-Transition Metal Alloys, edited by Strnat, K. J. (University of Dayton, Magnetics, KL-365, Dayton, Ohio 45469, USA), pp. 725–735.Google Scholar
16. Pinkerton, F. E., J. Mag. Magn. Mater. 54–57, 579 (1986).Google Scholar
17. Wohlfarth, E. P., J. Appl. Phys. 29, 595 (1958).Google Scholar
18. Gaunt, P., Hadjipanayis, G., and Ng, D., J. Mag. Magn. Mater. 54–57, 841 (1986).Google Scholar
19. Mishra, R. A., J. Appl. Phys. (to be published).Google Scholar
20. Li, D. and Strnat, K. J., J. Appl. Phys. 57, 4143 (1985).Google Scholar
21. Heinecke, U., Handstein, A., and Schneider, J., J. Mag. Magn. Mater. 53, 236 (1985).Google Scholar