Journal of Materials Science

, Volume 28, Issue 1, pp 203–217

Sintering characteristics of Fe and FeCo alloy ultrafine powders

  • Y. Sakka
  • T. Uchikoshi
  • E. Ozawa
Papers

Abstract

Sintering characteristics of three kinds of iron and FeCo alloy ultrafine powders (UFPs) in vacuum and a hydrogen atmosphere were examined by continuously measuring their dimensions, and observing their structural changes. The UFPs exposed to air contain mixtures of oxide and hydroxide phases. The oxide phase increased during heating in vacuum. The compacts of the UFPs shrunk slightly at temperatures between 450 and 700 K, where the surface oxides sintered, and then densified rapidly above 700 K. The shrinkage in a stream of hydrogen occurred at much lower temperatures than that in vacuum. The reduction reaction is ratecontrolled by an interface reaction and the reduction rate of the UFPs depends on the oxidation level, where the more highly oxidized UFPs tend to the lower reduction rate. Activation energies of the reduction rate constants of the iron UFPs and FeCo UFPs lie in the range 48–59 kJ mol−1.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    C. Hayashi, R. Ueda and A. Tasaki (eds.), “Choubiryushi (Ultrafine Particles)” (Mita Shuppankai, Tokyo, 1988).Google Scholar
  2. 2.
    S. Saito (ed.), “Choubiryushi Handobukku (Handbook of Ultrafine Particles)” (Fuji Tekunoshisutemu, Tokyo, 1990).Google Scholar
  3. 3.
    C. Herring, J. Appl. Phys. 21 (1950) 31.Google Scholar
  4. 4.
    D. L. Johnson and I. B. Cutler, J. Amer. Ceram. Soc. 46 (1963) 541, and references therein.Google Scholar
  5. 5.
    S. Iwama, and K. Hayakawa, Jpn J. Appl. Phys. 20 (1981) 335.Google Scholar
  6. 6.
    Y. Sakka, T. Uchikoshi and E. Ozawa, J. Less-Common Metals 147 (1989) 89.Google Scholar
  7. 7.
    Y. Sakka, J. Mater. Sci. Lett. 10 (1991) 426.Google Scholar
  8. 8.
    X. Zhu, B. Birringer, U. Herr and H. Gleiter, Phys. Rev. B35 (1987) 9085.Google Scholar
  9. 9.
    R. W. Siegel and H. Hahn, in “Current trends in the physics of materials”, edited by M. Yussouff (World Scientific, Singapore, 1988) p. 403.Google Scholar
  10. 10.
    K. Hayashi and H. Kihara, J. Jpn Inst. Metals. 50 (1986) 1089.Google Scholar
  11. 11.
    52 (1988) 343.Google Scholar
  12. 12.
    K. Hayashi and H. Etoh, 53 (1989) 221.Google Scholar
  13. 13.
    V. Keith and M. G. Ward, Cryogenics (1984) 249.Google Scholar
  14. 14.
    H. Franco, J. Bossy and H. Godfrin, ibid. (1984) 477.Google Scholar
  15. 15.
    T. Uchikoshi, Y. Sakka and E. Ozawa, J. Jpn Inst. Metals 53 (1989) 614.Google Scholar
  16. 16.
    Y. Sakka, T. Uchikoshi and S. Ohno, Proc. Jpn Congr. Mater. Res 32 (1989) 104.Google Scholar
  17. 17.
    Y. Sakka, T. Uchikoshi and E. Ozawa, Mater. Trans. JIM 31 (1990) 802.Google Scholar
  18. 18.
    T. Uchikoshi, Y. Sakka and S. Ohno, J. Jpn. Soc. Powder Powder Metall 37 (1990) 508.Google Scholar
  19. 19.
    Y. Sakka, S. Ohno and M. Uda, J. Amer. Ceram Soc. 75 (1992) 244.Google Scholar
  20. 20.
    E. Fuchita, M. Oda and S. Kashu, in “Proceedings of the 7th International Conference on Vacuum Metal” (Iron Steel Institute of Japan, 1982) p. 973.Google Scholar
  21. 21.
    S. Ohno and M. Uda, J. Chem. Soc. Jpn (1984) 924.Google Scholar
  22. 22.
    K. Haneda and A. H. Morrish, Surface Sci. 77 (1978) 584.Google Scholar
  23. 23.
    B. D. Culity, “Elements of X-ray Diffraction”, 2nd Edn, (Addison-Wesley, MA, 1978) p. 102.Google Scholar
  24. 24.
    T. Furubayashi, I. Nakatani, and N. Saegusa, J. Phys. Soc. Jpn 56 (1987) 1855.Google Scholar
  25. 25.
    Y. Sakka and T. Uchikoshi J. Jpn Inst. Metals 55 (1991) 219.Google Scholar
  26. 26.
    Y. Sakka, J. Mater. Sci. Lett. 10 (1991) 987.Google Scholar
  27. 27.
    J. M. Heras and E. V. Albano, Appl. Surf. Sci 17 (1983) 207.Google Scholar
  28. 28.
    T. Uchikoshi, M. Yoshitake, Y. Sakka, T. Furubayashi and I. Yoshihara, submitted to J. Chem. Soc. Jpn. Google Scholar
  29. 29.
    T. Uchikoshi and Y. Sakka, J. Jpn Inst. Metals. 55 (1991) 558.Google Scholar
  30. 30.
    W. M. Mckewan, Trans. Met. Soc. AIME 212 (1958) 791.Google Scholar
  31. 31.
    M. Tokuda, H. Yoshikoshi and M. Ohtani, Tetsu-to-Hagane 56 (1970) 1899.Google Scholar

Copyright information

© Chapman & Hall 1993

Authors and Affiliations

  • Y. Sakka
    • 1
  • T. Uchikoshi
    • 1
  • E. Ozawa
    • 1
  1. 1.National Research Institute for MetalsTokyoJapan
  2. 2.K. K. L'Air Liquide LaboratoriesIbarakiJapan

Personalised recommendations