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Samarium-Cobalt Phase Equilibria Revisited; Relevance to Permanent Magnets

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Published/Copyright: December 16, 2021
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International Journal of Materials Research
From the journal International Journal of Materials Research Volume 89 Issue 2

Abstract

In the binary system Sm–Co the region between Sm5Co19 (79.2 at.% Co) and Co is discussed. SmCo5 is not stable at low temperatures; it is transformed in the anomalous eutectoid reaction SmCo5 → Sm5Co19 +Sm2Co17, and the experimental evidence does not support other assumptions about this process. In this reaction, the crystallization of Sm5Co19 is suppressed or greatly retarded, leaving the appearance of simple precipitation of Sm2Co17. This precipitation, in any form, destroys the high coercivity that is otherwise obtained in sintered magnets. The conditions for possible spinodal decomposition are described, and it is shown why it cannot be responsible for the coercivity mechanism in binary SmCo5. The partial replacement of Co by Cu in SmCo5 also leads to the precipitation of Sm2Co17 but now, contrary to the behavior in binary Sm–Co, it actually enhances coercivity.

Abstract

Im Zweistoffsystem Sm–Co wird der Bereich zwischen Sm5Co19 (79.2 At.-% Co) und Co besprochen. SmCo5 ist bei tiefen Temperaturen nicht stabil, sondern zerfällt durch die anomale eutektoide Reaktion SmCo5 → SmsCo19 + Sm2Co17, wobei alternative Annahmen über diesen Vorgang experimentell nicht belegt werden können. Dabei wird die Kristallisation von Sm5Co19 unterdrückt bzw. wesentlich verzögert, so daß der Eindruck einfacher Ausscheidung von Sm2Co17 entsteht. Diese Ausscheidung, wie auch immer gestaltet, vernichtet die in Sintermagneten zu erwartende hohe Koerzitivfeldstärke. Die Bedingungen für das Auftreten einer spinodalen Entmischung werden untersucht, und es wird gezeigt, daß eine solche fär den Koerzitivitätsmechanismus in binärem SmCo5 nicht verantwortlich gemacht werden kann. Wird ein Teil des Co durch Cu ersetzt, so scheidet sich ebenfalls Sm2Co17 aus, doch wird in diesem Fall, entgegen dem Verhalten binärer Sm-Co-Legierungen, die Koerzitivität erhöht.

H. H. Stadelmaier Department of Materials Science and Engineering, North Carolina State University Box 7907, Raleigh, NC 27695-7907, USA
B. Reinsch Robert Bosch GmbH, Forschung 1, Abt. FV/FLW Werkstoffe Postfach 10 60 50, D-70049 Stuttgart, Germany
G. Petzow Max-Planck-Institut für Metallforschung Pulvermetallurgisches Laboratorium Heisenbergstr. 5, D-70569 Stuttgart, Germany

Dedicated to Prof. Dr.-Ing. habil. Dr.-Ing. E.h. Werner Schatt on the occasion of his 75th birthday

Literature

68Bus Buschow, K. H. J., van der Goot, A. S.: J. Less-Common Met. 14 (1968) 323–328.10.1016/0022-5088(68)90037-4Search in Google Scholar

69Bus Buschow, K. H. J.; Naastepad, P. A.; Westendorp, F. F.: J. Appl. Phys. 40 (1969) 4029–4032.10.1063/1.1657138Search in Google Scholar

69Nes Nesbitt, E. A.: J. Appl. Phys. 40 (1969)1259–1265.10.1063/1.1657619Search in Google Scholar

70Hof Hofer, F.: IEEE Trans. Magn. 6 (1970) 221–224.10.1109/TMAG.1970.1066730Search in Google Scholar

70Wes Westendorp, F. F.: Solid State Commun. 8 (1970) 139–141.10.1016/0038-1098(70)90065-7Search in Google Scholar

71Bus Buschow, K. H. J.; van der Goot, A. S.: Acta Cryst. B27 (1971) 1085–1088.10.1107/S0567740871003558Search in Google Scholar

72Bro den Broeder, F. J. A.; Buschow, K. H. J.: J. Less-Common Met. 29 (1972) 65-71.10.1016/0022-5088(72)90147-6Search in Google Scholar

72Giv Givord, D.; Givord, F.; Lemaire, R.; James, W. J.; Shah, J. S.: J. Less-Common Met. 29 (1972) 389–396.10.1016/0022-5088(72)90202-0Search in Google Scholar

73Bus Buschow, K. H. J.; den Broeder, F. J. A.: J. Less-Common Met. 33 (1973) 191–201.10.1016/0022-5088(73)90038-6Search in Google Scholar

73Kha Khan, Y.: Acta Cryst. B29 (1973) 2502–2507.10.1107/S0567740873006928Search in Google Scholar

73Nes Nesbitt, E. A.; Wernick, J. H.: Rare Earth Permanent Magnets, Academic Press, New York (1973).Search in Google Scholar

73Sme Smeggil, J. G.; Rao, P.; Livingston, J. D.; Koch, E. F: AIP Conf. Proc. 18 (1973) 1144–1148.Search in Google Scholar

74Bro den Broeder, F. J. A.; Westerhout, G. D.; Buschow, K. H. J.: Z. Metallkd. 65 (1974) 501–505.Search in Google Scholar

74Kha1 Khan, Y.: Acta Cryst. B30 (1974)1533–1537.10.1107/S0567740874005206Search in Google Scholar

74Kha2 Khan, Y.: Z. Metallkd. 65 (1974) 489 – 495.Search in Google Scholar

74Ray Ray, A. E.: Cobalt 1974-1 (1974) 13–20.Search in Google Scholar

74Wil Willson, M. C.; Janowiecki, R. J.: AIP Conf. Proc. 24 (1974) 689–690.10.1063/1.30239Search in Google Scholar

76Bro den Broeder, F. J. A.; Zijlstra, H.: J. Appl. Phys. 47 (1976) 2688–2695.10.1063/1.322990Search in Google Scholar

77Per Perry, A. J.: J. Less-Common Met. 51 (1977) 153–162.10.1016/0022-5088(77)90182-5Search in Google Scholar

78Nag Nagel, H.; Menth, A.: IEEE Trans. Magn. MAG 14 (1978) 671–673.10.1109/TMAG.1978.1059946Search in Google Scholar

79Gla Glardon, R.; Kurz, W.: Z. Metallkd. 70 (1979) 386–391.Search in Google Scholar

80Fid Fidler, J.; Kirchmayr, H.; Wernisch, J.: J. Less-Common Met. 71 (1980) 245–257.10.1016/0022-5088(80)90208-8Search in Google Scholar

83ElM ElMasry, N. A.; Stadelmaier, H. H.; Shahwan, C. J.; Jordan, L. T.: Z. Metallkd. 74 (1983) 33 – 37.Search in Google Scholar

84Sta Stadelmaier, H. H.: Z. Metallkd. 75 (1984) 227–230.Search in Google Scholar

86Chu Chuang, Y. C.; Wu, C. H.; Chang, S. C.; Li, T. C.; Wang, Y. C.: J. Less-Common Met. 125 (1986) 25–32.10.1016/0022-5088(86)90077-9Search in Google Scholar

86Sta Stadelmaier, H. H.; Schneider, G.; Ellner, M.: J. Less-Common Met. 115 (1986) L11-L14.10.1016/0022-5088(86)90163-3Search in Google Scholar

87Mey1 Meyer-Liautaud, F.; Allibert, C. H.; Castanet, R.: J. Less-Common Met. 127 (1987) 243–250.10.1016/0022-5088(87)90384-5Search in Google Scholar

87Mey2 Meyer-Liautaud, F.; Derkaoui, S.; Allibert, C. H.; Castanet, R.: J. Less-Common Met. 127 (1987) 231–242.10.1016/0022-5088(87)90383-3Search in Google Scholar

88Sta Stadelmaier, H. H.; Henig, E.-Th.; Schneider, G.; Petzow, G.: Z. Metallkd. 79 (1988) 313–316.Search in Google Scholar

89Der Derkaoui, S.; Allibert, C. H.: J. Less-Common Met. 154 (1989) 309–315.10.1016/0022-5088(89)90216-6Search in Google Scholar

90Mas Massalski, T. B. (ed.): Binary Alloy Phase Diagrams, 1st Ed., ASM International, Materials Park, OH (1986), 2nd Ed. (1990).Search in Google Scholar

91Str Strnat, K. J.; Strnat, R. M. W.: J. Magn. Magn. Mat. 100 (1991) 38–56.10.1016/0304-8853(91)90811-NSearch in Google Scholar

92Wu Wu, C. H.; Chuang, Y C.; Jin, X. M; Guan, X. H.: Z. Metallkd. 83 (1992) 32–34.Search in Google Scholar

93Ge Ge, W Q.; Wu, C. H.; Chuang, Y. C.: Z. Metallkd. 84 (1993) 165–169.Search in Google Scholar
Received: 1997-09-24
Published Online: 2021-12-16

© 1998 Carl Hanser Verlag, München

Articles in the same Issue

  1. Frontmatter
  2. Editorial
  3. Editorial
  4. Aufsätze
  5. Schwindungsverhalten von WC–Co Hartmetallen
  6. Melting Behaviour of (Ti, Mo)C–Co and (Ti, W)C–Co Alloys
  7. Melting Behaviour of (Ti, Mo)C–Ni and (Ti, W)C–Ni alloys
  8. Investigation of Swelling Behaviour of Ti–Al Elemental Powder Mixtures During Reaction Sintering
  9. Mechanical Behaviour of Granular Ceramic Films During Drying
  10. Grundlagen und neue Anwendungen der Kossel-Technik in der Materialforschung
  11. Samarium-Cobalt Phase Equilibria Revisited; Relevance to Permanent Magnets
  12. Dispersion Strengthening of Copper Alloys
  13. Thermomechanical Treatment of Shape Memory Alloys by Ausforming and Marforming
  14. High Cycle Fatigue Behaviour of Mo Alloyed Sintered Steel
  15. The Evolution of a Single Void under Irradiation
  16. Thermodynamics and Combustion Synthesis of Si–TiC–N and Si–TiO2–N
  17. Biologisierte Titanwerkstoffe
  18. Mitteilungen der Deutschen Gesellschaft für Materialkunde e.V.
  19. Zeitschrift für
https://doi.org/10.3139/ijmr-1998-0023

Articles in the same Issue

  1. Frontmatter
  2. Editorial
  3. Editorial
  4. Aufsätze
  5. Schwindungsverhalten von WC–Co Hartmetallen
  6. Melting Behaviour of (Ti, Mo)C–Co and (Ti, W)C–Co Alloys
  7. Melting Behaviour of (Ti, Mo)C–Ni and (Ti, W)C–Ni alloys
  8. Investigation of Swelling Behaviour of Ti–Al Elemental Powder Mixtures During Reaction Sintering
  9. Mechanical Behaviour of Granular Ceramic Films During Drying
  10. Grundlagen und neue Anwendungen der Kossel-Technik in der Materialforschung
  11. Samarium-Cobalt Phase Equilibria Revisited; Relevance to Permanent Magnets
  12. Dispersion Strengthening of Copper Alloys
  13. Thermomechanical Treatment of Shape Memory Alloys by Ausforming and Marforming
  14. High Cycle Fatigue Behaviour of Mo Alloyed Sintered Steel
  15. The Evolution of a Single Void under Irradiation
  16. Thermodynamics and Combustion Synthesis of Si–TiC–N and Si–TiO2–N
  17. Biologisierte Titanwerkstoffe
  18. Mitteilungen der Deutschen Gesellschaft für Materialkunde e.V.
  19. Zeitschrift für
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