Journal of Materials Science

, Volume 16, Issue 11, pp 3183–3193

Annealing behaviour of amorphous Fe80B20 on continuous heating

  • O. T. Inal
  • C. V. Robino
  • L. Keller
  • F. G. Yost
  • M. M. Karnowsky
Papers

DOI: 10.1007/BF00540327

Cite this article as:
Inal, O.T., Robino, C.V., Keller, L. et al. J Mater Sci (1981) 16: 3183. doi:10.1007/BF00540327

Abstract

Resistance measurements during direct heating of Fe80B20 amorphous alloys indicate phase changes occur at 395, 500, 720 and 840° C. Samples heated to these temperatures, and maintained for five minutes in a neutral atmosphere, show that a hardness maximum occurs at the crystallization temperature of 395° C and that annealing at 500° C produces a material with the same hardness. Above 500° C the microhardness is seen to drop below that of the amorphous alloy. Saturation magnetization measurements show a steady increase following each anneal, up to a temperature of 720° C, and the rate of increase is seen to drop in the range of 720 to 840° C. X-ray diffraction studies show that only a small fraction of the matrix is crystallized following the anneal at 395° C and the transformed phases are α-Fe and Fe3B. Following annealing at 500° C, an increased proportion of α-Fe and Fe3B are observed with complete crystallinity while samples heattreated at 720° C are seen to consist of a three-phase mixture of α-Fe, Fe23B6 and Fe2B. Annealing at 840° C is seen to produce an equilibrium phase mixture of α-Fe and Fe2B phases. Only in the sample annealed at 395° C is a fraction of the amorphous phase seen to persist, indicating that a 5 min anneal is not sufficient, at this temperature, to induce complete crystallization. These structural features are corroborated by field ion microscope analyses, made at liquid nitrogen temperature in a medium of pure neon, and scanning electron microscopy, and are also consistent with our earlier study involving the isothermal annealing, for various times, of Fe80B20 alloy at 780° C.

Copyright information

© Chapman and Hall Ltd. 1981

Authors and Affiliations

  • O. T. Inal
    • 1
  • C. V. Robino
    • 1
  • L. Keller
    • 1
  • F. G. Yost
    • 2
  • M. M. Karnowsky
    • 2
  1. 1.Department of Metallurgical and Materials EngineeringNew Mexico Institute of Mining and TechnologySocorroUSA
  2. 2.Sandia National LaboratoriesAlbuquerqueUSA

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