Iowa State University Patents
Iowa State University Research Foundation, Inc.
9-8-1998
Carbide/nitride grain refined rare earth-iron-boron
permanent magnet and method of making
R. William McCallum
Iowa State University, mccallum@ameslab.gov
Daniel J. Branagan
Iowa State UniversityFollow this and additional works at:
http://lib.dr.iastate.edu/patents
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Recommended Citation
McCallum, R. William and Branagan, Daniel J., "Carbide/nitride grain refined rare earth-iron-boron permanent magnet and method of making" (1998).Iowa State University Patents. 273.
comprising RE, Fe and/or Co, and B (where RE is one or more rare earth elements) and 2) TR (where TR is a transition metal selected from at least one of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, and Al) and at least one of C and N are provided in the base alloy composition melt in substantially stoichiometric amounts to form a thermodynamically stable compound (e.g. TR carbide, nitride or carbonitride). The melt is rapidly solidified in a manner to form particulates having a substantially amorphous (metallic glass) structure and a dispersion of primary TRC, TRN and/or TRC/N precipitates. The amorphous particulates are heated above the crystallization temperature of the base alloy composition to nucleate and grow a hard magnetic phase to an optimum grain size and to form secondary TRC, TRN and/or TRC/N precipitates dispersed at grain boundaries. The crystallized particulates are consolidated at an elevated temperature to form a shape. During elevated temperature consolidation, the primary and secondary precipitates act to pin the grain boundaries and minimize deleterious grain growth that is harmful to magnetic properties.
Keywords
Ames Laboratory, Materials Science and Engineering
Disciplines
Materials Science and Engineering
United States Patent [19]
McCallum et al.
US005803992A
[11] Patent Number:
[45]
Date of Patent:
5,803,992
Sep. s, 1998
[54]
[75]
[73]
CARBIDE/NITRIDE GRAIN REFINED RARE FOREIGN PATENT DOCUMENTS EARTH-IRON-BORON PERMANENT
0443647 8/1991 European Pat. Off. ... .. 148/302
MAGNET AND METHOD OF MAKING 5-105902 4/1993 Japan ... .. 148/302
Inventors: R. William McCallum; Daniel J.
Branagan, both of Ames, Iowa Primary Examiner—John Sheehan
Attorney, Agent, or Firm—EdWard J. Timmer Assignee: Iowa State University Research
Foundation, Inc., Ames, Iowa [57] ABSTRACT
A method of making a permanent magnet Wherein 1) a melt
Appl. No.: 564,425 is formed having a base alloy composition comprising RE,
. _ Fe and/or Co, and B (Where RE is one or more rare earth
Flled' NOV‘ 29’ 1995 elements) and 2) TR (Where TR is a transition metal selected
. . from at least one of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, and Al) Related U'S' Apphcatlon Data and at least one of C and N are provided in the base alloy Division of Ser_ No 2327837’ Apr‘ 25’ 1994’ Pat‘ NO‘ composition melt in substantially stoichiometric amounts to
5,486,240' form a thermodynamically stable compound (eg TR
6 carbide, nitride or carbonitride). The melt is rapidly solidi
IIlt- Cl- ... .. ?ed in a manner to form particulates having a Substantially
U.S. Cl. ... .. 148/302; 420/83; 420/121; amorphous (metallic glass) Structure and a dispersion of
148/121 primary TRC, TRN and/or TRC/N precipitates. The amor
Fleld of Search ... .. phous particulates are heated above the Crystallization tern
420/83, 121 perature of the base alloy composition to nucleate and groW
_ a hard magnetic phase to an optimum grain siZe and to form
References Clted secondary TRC, TRN and/or TRC/N precipitates dispersed
Us PATENT DOCUMENTS at grain boundaries. The crystallized particulates are con
sohdated at an elevated temperature to form a shape. During
4,597,938 7/1986 Matsuura et al. ... .. 419/23 elevated temperature Consolidation, the primary and Second
476017875 7/1986 Yamamoto et a1- - ~~ 419/23 ary precipitates act to pin the grain boundaries and minimize
478017340 1/1989 Inoue et a1‘ """" " 148/103 deleterious grain groWth that is harmful to magnetic prop
4,919,732 4/1990 Yang et al. 148/103 er?es
5,162,064 11/1992 Kim et al. . 148/302 ' 5,172,751 12/1992 Croat ... .. 148/101
5,240,513 8/1993 McCallum et al. ... .. 148/104 5 Claims, 32 Drawing Sheets
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