Gm Global Technolgoy Operations, Inc.

Robert W Lee

John J Croat

Earl G Brewer

Peter Vernia

Neal A Schaffel

A method is disclosed of hot working a magnetically soft cast crystalline material containing grains of RE.sub.2 TM.sub.14 B and an RE metal, rich intergranular second phase into anisotropic permanent magnet bodies.

Permanent magnet manufacture from very low coercivity crystalline rare

Magnetically isotropic, fine grain, RE.sub.2 Fe.sub.4 B phase containing particulate material is hot pressed to full density and bonded to a metal backing layer of desired shape and composition. Additionally, if desired, the fully dense isotropic material can be further deformed in a direction lateral to the press direction so as to strain the particles to align the preferred magnetic axes of the crystal grains therein and thus form a laminate of a magnetically anisotropic magnet layer bonded to a metal backing layer.

Method for producing laminated bodies comprising an RE-FE-B type

This invention relates to permanent bonded magnets of very finely crystalline, melt-spun, rare earth-iron alloys. The compacts are magnetically isotropic.

Bonded rare earth-iron magnets

A method to produce rare earth (RE), iron, boron type anisotropic permanently magnetic material includes forming magnetically isotropic coarse powder particles of melt-spun alloy with a very fine grain RE.sub.2 FE.sub.14 B phase. The particles are mixed with inert particles of a size and of a weight percentage of the mixture to separate the powder particles for preventing hot work bonding therebetween. The mixture is hot pressed to cause the magnetically isotropic particles to be compressed in a direction parallel to the press direction so as to strain the particles to cause crystallites to be oriented along a crystallographically preferred magnetic axis resulting in particles of anisotropic permanently magnetic material.

Method for producing anisotropic RE-FE-B type magnetically aligned

A method to increase the volume fraction of magnetically aligned material in rare earth (RE), iron, boron type anisotropic permanently magnetic material includes forming an adaptively shaped fully dense substantially magnetically isotropic preform from relatively coarse powder particles of melt spun alloy with a very fine grain Re.sub.2 Fe.sub.14 B phase. The preform is heated and die upset to provide uniformity of strain in the perform as it is conformed to the die thereby to cause an increased percentage of the crystallites to be oriented along a crystallographically preferred magnetic axis which increases the energy product of a resultant magnet.

Die-upset manufacture to produce high volume fractions of RE-Fe-B type

High energy product, magnetically anisotropic permanent magnets are produced by hot working overquenched or fine grained, melt-spun materials comprising iron, neodymium and/or praseodymium, and boron to produce a fully densified, fine grained body that has undergone plastic flow.

Iron-rare earth-boron permanent magnets by hot working

Iron-rare earth-boron permanent

In accordance with a preferred embodiment, an arcuate magnet is formed by selectively hot working a composition including iron, neodymium and/or praseodymium, and boron such that an edge of the arcuate has greater apparent coercivity than a central region and the central region has a higher remanence than the edge.

Hot pressed permanent magnet having high and low coercivity regions

In a preferred embodiment thin layers of rare earth metal-cobalt powder comprising an outer layer of RCo.sub.5 and a discrete transitional layer of R.sub.2 Co.sub.17 are compressed against an adjacent thicker layer of iron powder to form a laminated green compact, with the rare earth-cobalt powdered material being magnetically aligned. The green laminate body is then sintered to densify the rare earth-cobalt material layer to a body wherein the pores are substantially noninterconnecting. The laminate structure is then magnetized. By this method a strong rare earth-cobalt (RCo.sub.5) permanent magnet body is produced in which the rare earth-cobalt layer may be very thin (of the order of 1 to 2 millimeters) but of relatively large surface area and supported by a strong iron layer so as to be durable in handling, manufacturing and use. It is possible to press an RCo.sub.5 layer directly onto a powdered iron layer when the oxygen content of the iron is suitably low. The method will also produce an R.sub.2 Co.sub.17 -iron composite.

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Troy, MI, United States of America

Robert W Lee