Structural and magnetic properties of nanocrystalline Fe-rich Fe-Nb-Nd-B sintered magnets produced by consolidating amorphous powders

Author

Kojima, Akira ; Makino, Akihiro ; Inoue, A.

Author_Institution

Fac. of Eng., Tohoku Univ., Sendai, Japan

Volume

33

Issue

5

fYear

1997

fDate

9/1/1997 12:00:00 AM

Firstpage

3817

Lastpage

3819

Abstract

Nanocrystalline bulk Fe₈₈Nb₂Nd₅B ₅ and Fe₈₆Nb₂Nd₇B₅ alloys were made by consolidating amorphous powders with an electric-pulse-current sintering method and subsequent annealing. Bulk alloy made by consolidating amorphous powders has a higher density (the maximum density could reach 7.5 g/cm³ consolidating at 873 K and 636 MPa) than that made by consolidating crystalline powders, presumably because the amorphous alloy softens around the crystallization temperature. The structure formed after annealing at 1023 K for 180 s shows a nanocrystalline composite consisting of bcc-Fe, Nd₂Fe ₁₄B and Fe₃B or Fe₂B phases with grain sizes of 20-40 nm. The nanocrystalline bulk Fe₈₈Nb₂Nd₅B₅ alloy shows hard magnetic properties, remanence of 1.05 T, coercive force (H_cJ) of 263 kA/m, maximum energy product ((BH)_max) of 75 kJ/m³

Keywords

amorphous magnetic materials; annealing; boron alloys; coercive force; composite materials; crystallisation; ferromagnetic materials; grain size; iron alloys; magnetic hysteresis; nanostructured materials; neodymium alloys; niobium alloys; permanent magnets; powder metallurgy; remanence; sintering; 1023 K; 20 to 40 nm; 636 MPa; 873 K; Fe₈₆Nb₂Nd₇B₅; Fe₈₈Nb₂Nd₅B₅; amorphous alloy; amorphous powders; annealing; coercive force; consolidating amorphous powders; crystallization temperature; density; electric-pulse-current sintering method; grain sizes; hard magnetic properties; magnetic properties; maximum energy product; nanocrystalline Fe-rich Fe-Nb-Nd-B sintered magnets; nanocrystalline composite; remanence; structural properties; Amorphous materials; Annealing; Crystallization; Grain size; Iron alloys; Magnetic properties; Neodymium; Niobium alloys; Powders; Temperature;

fLanguage

English

Journal_Title

Magnetics, IEEE Transactions on

Publisher

ieee

ISSN

0018-9464

Type

jour

DOI

10.1109/20.619581

Filename

619581