Carbide/nitride grain refined rare earth iron boron permanent magnet and method of making

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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 University

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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" (1996).Iowa State University Patents. 177.

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Carbide/nitride grain refined rare earth-iron-boron permanent magnet

and method of making

Abstract

A method of making a permanent magnet wherein 1) a melt is formed having a base alloy composition 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 & Engineering

Disciplines

Engineering | Materials Science and Engineering

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[54] CARBIDE/NITRIDE GRAIN REFINED RARE EARTH-IRON-BORON PERMANENT MAGNET AND METHOD OF MAKING

Primary Examiner—John Sheehan

Attorney, Agent, or Firm—Edward J. Timmer [57] ABSTRACT

[75] Inventors: wllhamtyticafuxm; Di‘mel J‘ A method of making a permanent magnet wherein l) a melt

anagan’ 0 o mes’ owa is formed having a base alloy composition comprising RE,

. _ . . Fe and/or Co, and B (where RE is one or more rare earth

[731 Asslgnec' gxzdsgz?nu?zerilgegifxgch 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 [21] Appl' No" 232’837 composition melt in substantially stoichiometric amounts to [22] Filed; Am._ 25, 1994 form a thermodynamically stable compound (e.g. TR car

6 bide, nitride or carbonitride). The melt is rapidly solidi?ed

Int. Cl- ... .. in a manner to fol-1n particulates having a Substantially

[52] US. Cl. ... .. .. 148/102; 148/104; 75/348; amorphous (metallic glass) structure and a dispersion of

75/349; 419/61; 419/66 primary TRC, TRN and/or TRC/N precipitates. The amor

[58] Field of Search ... .. 148/101, 104, phous particulates are heated above the crystallization tem

148/ 102; 75/348, 349; 419/61, 66; 164/462, perature of the base alloy composition to nucleate and grow 463, 479 a hard magnetic phase to an optimum grain size and to form secondary TRC, TRN and/or TRC/N precipitates dispersed [56] References Cited at grain boundaries. The crystallized particulates are con

solidated at an elevated temperature to form a shape. During

U‘S‘ PATENT DOCUMENTS elevated temperature consolidation, the primary and second 4,597,938 7/1986 Matsuura et a1. ... .. 419/23 ary precipitates act to pin the grain boundaries and minimize 4,601,875 7/1986 Yamamoto et a1. ... .. 419/23 deleterious grain growth that is harmful to magnetic prop

4,801,340 l/1989 Inoue et a1. . . . . . . .. 148/103 enies,

4,919,732 4/1990 Yang et a1. 148/103

5,172,751 12/1992 Croat . . . . . . .. 148/101

5,240,513 8/1993 McCallum et a1. ... .. 1481104 13 Claims, 32 Drawing Sheets

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Jan. 23, 1996

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Figure

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