Hard magnetic properties of bulk amorphous alloys

Akihisa Inoue, Tao Zhang, Akira Takeuchi

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)

Abstract

The amorphous phase in the Nd-Fe-Al and Pr-Fe-Al systems is formed in extremely wide composition ranges of 0 to 90 at% Fe and 0 to 93 at% Al by melt spinning. Ferromagnetic Ln90-xFexAl10 (Ln=Nd or Pr) bulk amorphous alloys with high coercive force at room temperature are obtained by a copper mold casting method. The maximum diameter of the cylindrical amorphous samples is 12 mm for the Nd-30%Fe-Al alloy and 3 mm for the Pr-30%Fe-Al alloys and decreases with deviating Fe content. Neither glass transition nor supercooled liquid region is observed in the temperature range before crystallization (T < Tx), which is different from other bulk amorphous alloys exhibiting wide supercooled liquid regions. The extremely high Tx/Tm and small ΔTm(=Tm-Tx) values are the reason for the achievement of large glass-forming ability in these systems. The bulk amorphous Ln60Fe30Al10 alloys are ferromagnetic with the Curie temperature (Tc) of 515 to 600 K which are much higher than those for Nd-Fe and Pr-Fe binary amorphous ribbons. The remanence (Br) and intrinsic coercive force (iHc) are 0.089 to 0.122 T and 277 to 321 kA/m, respectively, and the crystallization to Ln+Al2Ln+δ phases causes a ferromagnetic- to -paramagnetic phase transition. Thus, the hard magnetic properties are achieved only in the amorphous state.

Original languageEnglish
Pages (from-to)261-269
Number of pages9
JournalScience Reports of the Rerearch Institutes Tohoku University Series A-Physics
Volume44
Issue number2
Publication statusPublished - 1997 Mar 1

Keywords

  • Bulk amorphous permanent magnet
  • Copper mold casting
  • Ferromagnetic bulk amorphous alloy
  • Ferromagnetic cluster
  • High coercive force
  • High reduced glass transition temperature
  • Large glass-forming ability
  • Praseodymium-iron-aluminum alloy

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Metals and Alloys

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