Soft and hard magnetic properties of nanocrystalline Fe-M-B (M=Zr, Nd) base alloys containing intergranular amorphous phase

A. Inoue, A. Takeuchi, A. Makino, T. Masumoto

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

This paper reviews our recent results of the soft and hard magnetic properties of nanocrystalline Fe-rich Fe-M-B (M=Nd or Zr) base alloys containing an intergranular amorphous phase. Based on the previous results that the soft magnetic alloys in Fe-Si-B-Nb-Cu and Fe-Zr-B systems do not have zero magnetostriction (λb), the effect of the additional Al or Si on the λs and magnetic properties was examined for the nanocrystalline Fe-Zr-B-Al and Fe-Zr-B-Si alloys. The soft magnetic properties of high Bs above 1.5 T and high μe above 1.5×104 combined with zero λs were obtained for the Fe88Zr7B3Al2 and Fe86Zr7B3Si4 alloys annealed for 3.6 ks in the annealing temperature (Ta) range of 823 to 923 K. This is in contrast to the previous result that the good soft magnetic properties of the nanocrystalline Fe90Zr7B3 alloy are obtained in the narrow Ta range around 923 K. The remarkable extension of the Ta range seems to be attributed to the zero λs. The replacement of Zr by Nd in the Fe90M7B3 alloys was found to cause rather good hard magnetic properties of 1.3 T for Br. 260 kA/m for iHc and 146 kJ/m3 for (BH)max in a triplex nanostructure of bcc-Fe with a size of 20 nm, tetragonal Fe14Nd2B with a size of 15 nm and intergranular amorphous phase with a thickness of 5 to 10 nm. The hard magnetic properties arc obtained for the nanostructure containing 80 % soft magnetic phases and 20 % Fe14Nd2B in volume. The notable result is presumably due to the effective action of the intergranular amorphous network phase which can act as a resistance against the micleation of the reversion of magnetic domain walls leading to the increase in iHc as well as an exchange magnetic coupling medium between bcc-Fe and bcc-Fe or tetragonal Fe14Nd2B phases leading to the high Br. This presumption is also supported from the result that no good hard magnetic properties are obtained for the over annealed sample without intergranular amorphous phase as well as for the use of the sample which does not consist of a mostly single amorphous phase in the as-quenched state. Thus, the soft and hard magnetic properties for the Fe-M-B alloys are obtained only in the optimal nanostructures. The fabrication of a new nanostructure is expected to cause the appearance of other function properties even at compositions where no useful properties have not been obtained.

Original languageEnglish
Pages (from-to)143-156
Number of pages14
JournalScience Reports of the Rerearch Institutes Tohoku University Series A-Physics
Volume42
Issue number1
Publication statusPublished - 1996 Mar 1

Keywords

  • Amorphous phase
  • Hard magnetic properties
  • Iron base alloys
  • Nanocrystallization
  • Soft magnetic properties

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Metals and Alloys

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