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Title: Production method for making rare earth compounds

Abstract

A method of making a rare earth compound, such as a earth-transition metal permanent magnet compound, without the need for producing rare earth metal as a process step, comprises carbothermically reacting a rare earth oxide to form a rare earth carbide and heating the rare earth carbide, a compound-forming reactant (e.g., a transition metal and optional boron), and a carbide-forming element (e.g., a refractory metal) that forms a carbide that is more thermodynamically favorable than the rare earth carbide whereby the rare earth compound (e.g., Nd{sub 2}Fe{sub 14}B or LaNi{sub 5}) and a carbide of the carbide-forming element are formed.

Inventors:
; ; ; ;
Publication Date:
Research Org.:
Iowa State University
Sponsoring Org.:
USDOE, Washington, DC (United States)
OSTI Identifier:
563707
Patent Number(s):
US 5,690,889/A/
Application Number:
PAN: 8-605,324
Assignee:
Iowa State Univ. Research Foundation, Inc., Ames, IA (United States) PTO; SCA: 360101; PA: EDB-98:014956; SN: 98001896340
DOE Contract Number:
W-7405-ENG-82
Resource Type:
Patent
Resource Relation:
Other Information: PBD: 25 Nov 1997
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; SYNTHESIS; NEODYMIUM ALLOYS; IRON ALLOYS; BORON ALLOYS; LANTHANUM ALLOYS; NICKEL BASE ALLOYS; MAGNETIC MATERIALS; PERMANENT MAGNETS; RARE EARTH COMPOUNDS; CARBIDES

Citation Formats

McCallum, R.W., Ellis, T.W., Dennis, K.W., Hofer, R.J., and Branagan, D.J. Production method for making rare earth compounds. United States: N. p., 1997. Web.
McCallum, R.W., Ellis, T.W., Dennis, K.W., Hofer, R.J., & Branagan, D.J. Production method for making rare earth compounds. United States.
McCallum, R.W., Ellis, T.W., Dennis, K.W., Hofer, R.J., and Branagan, D.J. Tue . "Production method for making rare earth compounds". United States. doi:.
@article{osti_563707,
title = {Production method for making rare earth compounds},
author = {McCallum, R.W. and Ellis, T.W. and Dennis, K.W. and Hofer, R.J. and Branagan, D.J.},
abstractNote = {A method of making a rare earth compound, such as a earth-transition metal permanent magnet compound, without the need for producing rare earth metal as a process step, comprises carbothermically reacting a rare earth oxide to form a rare earth carbide and heating the rare earth carbide, a compound-forming reactant (e.g., a transition metal and optional boron), and a carbide-forming element (e.g., a refractory metal) that forms a carbide that is more thermodynamically favorable than the rare earth carbide whereby the rare earth compound (e.g., Nd{sub 2}Fe{sub 14}B or LaNi{sub 5}) and a carbide of the carbide-forming element are formed.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Nov 25 00:00:00 EST 1997},
month = {Tue Nov 25 00:00:00 EST 1997}
}
  • A method of making a rare earth compound, such as a earth-transition metal permanent magnet compound, without the need for producing rare earth metal as a process step, comprises carbothermically reacting a rare earth oxide to form a rare earth carbide and heating the rare earth carbide, a compound-forming reactant (e.g. a transition metal and optional boron), and a carbide-forming element (e.g. a refractory metal) that forms a carbide that is more thermodynamically favorable than the rare earth carbide whereby the rare earth compound (e.g. Nd.sub.2 Fe.sub.14 B or LaNi.sub.5) and a carbide of the carbide-forming element are formed.
  • This patent describes a method for producing rare earth-ferromagnetic metal alloy permanent magnets, comprising the steps of: (a) mixing a particulate additive material selected from the group consisting of refractory oxides, carbides, and nitrides, in an amount which provides about 0.1 percent to about 2 percent by weight additive material in the mixture, with a major amount of a particulate rare earth-ferromagnetic metal alloy and a minor amount of a particulate sintering aid alloy; (b) aligning magnetic domains of the mixture in a magnetic field; (c) compacting the aligned mixture to form a shape; and (d) sintering the compacted shape.
  • A method of making a permanent magnet is disclosed 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 inmore » 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. 33 figs.« less
  • An improved molten metal containment vessel is disclosed in which wetting of the vessel's inner wall surfaces by molten metal is inhibited by coating at least the inner surfaces of the containment vessel with one or more rare earth oxysulfide or rare earth sulfide compounds to inhibit wetting and or adherence by the molten metal to the surfaces of the containment vessel.
  • 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 mannermore » 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.« less