Title :
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
fDate :
9/1/1997 12:00:00 AM
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 (HcJ ) 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;
Journal_Title :
Magnetics, IEEE Transactions on
