A production method includes producing a rare-earth magnet precursor (S′) by performing first hot working in which, in two side surfaces of a sintered body, which are parallel to a pressing direction and are opposite to each other, one side surface is brought to a constrained state to suppress deformation, and the other side surface is brought to an unconstrained state to permit deformation; and producing a rare-earth magnet by performing second hot working in which, in two side surfaces (S′1, S′2) of the rare-earth magnet precursor (S′), which are parallel to the pressing direction, a side surface (S′2), which is in the unconstrained state in the first hot working, is brought to the constrained state to suppress deformation, and a side surface (S′1), which is in the constrained state in the first hot working, is brought to the unconstrained state to permit deformation.

A metal powder capable of producing a dust core having a high saturation magnetic flux density, excellent rust resistance, and a low iron loss. The metal powder includes from 1.0% to 15.0% of Si, from 1.0% to 13.0% of Cr, from 10 ppm to 10000 ppm of Cl, from 100 ppm to 10000 ppm of S (sulfur), and from 0.2% to 7.0% of O (oxygen) by mass concentration, the remainder including Fe and unavoidable impurities, in which the average particle diameter of the metal powder is from 0.1 μm to 2.0 μm. This facilitates the production of a dust core having a high magnetic flux density, excellent rust resistance, and a low iron loss.

Disclosed are a rare-earth permanent magnet having improved magnetic properties and a method of manufacturing the same. A method of manufacturing a rare-earth permanent magnet may include: preparing a mixed powder including i) a first alloy represented by R1.sub.aR2.sub.bB.sub.cM.sub.dFe.sub.bal and ii) a second alloy represented by R2.sub.bB.sub.cM.sub.dFe.sub.bal where R1 is one or two or more of La, Ce, and Y; R2 is a rare-earth element except for La, Ce, and Y; and M is a metal element; press-forming and sintering the prepared mixed powder in a magnetic field to prepare a sintered body; and performing a heat treatment based on diffusion temperature conditions of an R1 component and an R2 component contained in the prepared sintered body.

A dual-rotor machine comprising a dual rotor support structure rotatably connected to a frame. A stationary stator is disposed between the rotors and is fixed to the frame. An inner rotor and outer rotor, each comprising a permanent magnet Halbach array, are coaxially disposed with the stator and are rotable about the stator. In this configuration, the inner rotor channels its magnetic flux to its outside, while the outer rotor channels its magnetic flux to its inside. The magnetic flux density at the stator for the dual-rotor machine can be as high as 2 Tesla or higher for high-grade neodymium-iron-boron permanent magnet material, and the stored magnetic energy for conversion to mechanical or electrical energy available to the stator may be at least 0.5 kJ/m. The rotor Halbach arrays may comprise monolithic permanent magnets with continuously variable magnetic field direction.

A method for producing a NdFeB system sintered magnet. The method includes: a hydrogen pulverization process, in which coarse powder of a NdFeB system alloy is prepared by coarsely pulverizing a lump of NdFeB system alloy by making this lump occlude hydrogen; a fine pulverization process, in which fine powder is prepared by performing fine pulverization for further pulverizing the coarse powder; a filling process, in which the fine powder is put into a filling container; an orienting process, in which the fine powder in the filling container is oriented; and a sintering process, in which the fine powder after the orienting process is sintered as held in the filling container. The processes from hydrogen pulverization through orienting are performed with neither dehydrogenation heating nor evacuation each for desorbing hydrogen occluded in the hydrogen pulverization process. The processes from hydrogen pulverization through sintering are performed in an oxygen-free atmosphere.

Permanent magnets and methods of making the same are disclosed herein. The permanent magnets include a 3D-printed, i.e., additively manufactured, framework and an infiltrate such that there is a discrete magnetic phase and a discrete non-magnetic phase or two discrete magnetic phases. The infiltrate may provide superior strength, elasticity or magnetic properties.

A permanent magnet is expressed by a composition formula: R.sub.pFe.sub.qM.sub.rCu.sub.sCo.sub.100-p-q-r-s. The magnet includes a crystal grain having a main phase including a TbCu.sub.7 crystal phase, and a volume ratio of the TbCu.sub.7 crystal phase to the main phase is 95% or more.

A mold which is inexpensive and easy to process and does not embrittle. Also provided is a process by which a sintered NdFeB magnet can be produced using the mold without suffering bending or deformation. At least part (e.g., a bottom plate) of the mold is made of a carbon material. Carbon materials have lower friction with a sinter during sintering than metals. The mold hence enables a sintered NdFeB magnet to be produced without suffering the bending or deformation caused by friction due to sintering shrinkage. Carbon materials are inexpensive and easy to process. The mold does not embrittle even when repeatedly used. Such effects can be significantly produced when a carbon material is used as the bottom plate, on which the load of the sinter is imposed during sintering.

A method of fabricating a curvilinear magnet includes forming at least one slot in a material billet. The slotted material billet is inserted into a mold having a curvilinear pocket. The mold is closed around the slotted material billet such that the slotted material billet conforms to the curvilinear pocket and forms a curvilinear billet. The curvilinear billet is arranged in a structure. The curvilinear billet arranged in the structure is then magnetized.

A rare earth permanent magnet includes a main phase containing: a rare earth element R of one or more types including Nd; an element L of one or more types selected from a group consisting of Co, Be, Li, Al, and Si; B; and Fe, wherein crystals which form the main phase belong to P4.sub.2/mnm; some of B atoms occupying a 4f site of the crystals are substituted with atoms of the element L; each distribution of Nd atoms and the atoms of the element L appears along a C-axis direction of the crystals in a plurality of cycles; and the rare earth permanent magnet includes an area where a cycle of the atoms of the element L matches a cycle of the Nd atoms.