A rare earth sintered magnet is prepared by a method comprising the steps of melting raw materials to form an alloy, pulverizing the alloy into a fine powder, shaping the fine powder into a compact, and sintering the compact. The pulverizing step includes a coarse pulverizing step including hydrogen decrepitation and a fine pulverizing step, and further includes the step of adding a lubricant. The sintering step includes an atmosphere heat treatment including heating the compact at a temperature from the lubricant decomposition temperature to the sintering temperature and holding at the temperature for a time, in an inert gas atmosphere, and a vacuum heat treatment. The sintered magnet has a low impurity concentration and a narrow carbon concentration distribution.

The present invention provides a method for manufacturing a rare-earth magnet, the method comprising the steps of preparing a rare-earth magnet raw material powder including R, Fe and B as composition components (R is one or more elements selected from the rare earth elements including Y and Sc); packing the raw material powder into a molding die, and compacting and molding the raw material powder while applying a magnetic field, wherein, in the compacting and molding step, compacting is performed biaxially, in the directions of X and Y axes, when the magnetic field is applied in the direction of Z axis.

A sintered R.sub.2M.sub.17 magnet is provided that comprises at least 70 Vol % of a Sm.sub.2M.sub.17 phase, wherein R is at least one of the group consisting of Ce, La, Nd, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm,

Yt, Lu and Y, and M comprises Co, Fe, Cu and Zr. In an area of the R.sub.2M.sub.17 sintered magnet of 200 by 200 μm viewed in a Kerr micrograph, an areal proportion of demagnetised regions after application of an internal opposing field of 1200 kA/m is less than 5% or less than 2%.

This invention provides methods for fabricating a hard or soft magnet with tailorable magnetic and crystallographic orientations. Methods are disclosed to individually tailor three-dimensional voxels for selected crystallographic orientations and, independently, selected magnetic orientations with location specificity throughout a magnet. Some variations provide a method of making a magnet, comprising: providing a feedstock composition containing magnetic or magnetically susceptible materials; exposing the feedstock composition to an energy source for melting, thereby generating a first melt layer; solidifying the first melt layer in the presence of an externally applied magnetic field, thereby generating a magnetic metal layer containing a plurality of individual voxels; optionally repeating to generate a plurality of solid layers; and recovering a magnet comprising the magnetic metal layer(s), wherein the externally applied magnetic field has a magnetic-field orientation that is selected to control a magnetic axis and a crystallographic texture within the magnetic metal layer(s).

A sintered ferrite magnet having a composition of metal elements of Ca, R, A, Fe and Co, which is represented by the general formula of Ca.sub.1−x−yR.sub.xA.sub.yFe.sub.2n−zCo.sub.z, wherein R is at least one of rare earth elements indispensably including La; A is Sr and/or Ba; x, y, z and n represent the atomic ratios of Ca, R, A, Fe and Co; 2n represents a molar ratio expressed by 2n=(Fe+Co)/(Ca+R+A); and x, y, z and n meet the conditions of 0.15≤x≤0.35, 0.05≤y≤0.40, (1−x−y)>y, 0<z≤0.18, and 7.5≤(2n−z)<11.0.

The present disclosure refers to a method for preparing sintered NdFeB magnets, including: a) Preparing alloy flakes from a raw material by strip casting, performing a hydrogen decrepitation to produce alloy pieces, pulverization the alloy pieces to an alloy powder, performing molding and orientation, cold isostatic pressing, and getting a green compact; b) Putting the green compact into a vacuum furnace and performing a first sintering step in 830 to 880° C. for 2 to 10 hours and 5×10.sup.−1 Pa or less; c) Performing a second sintering step while applying a pressure to the green compact achieved by step b), the pressure is 1 MPa to 5 MPa and the sintering temperature is 720 to 850° C. for 15 to 60 minutes, and the temperature of the first sintering step is at least 10° C. higher than that of the second sintering step; d) Subjecting the sintered magnet of step c) to an annealing treatment.

A compression-molding method for a permanent includes: providing a drive coil to generate an electromagnetic force when a transient current is passed into the drive coil, so as to apply a molding compression force to magnetic powder under compression, and providing an orientation coil to generate an orientation magnetic field when a transient current is passed into the orientation coil, thereby providing the magnetic powder under compression with an anisotropic property; and synchronously passing the transient currents to the drive coil and the orientation coil to synchronously generate the electromagnetic force and the orientation magnetic field, thereby completing compression-molding of the permanent magnet, wherein a magnitude of the electromagnetic force and an intensity of the orientation magnetic field are respectively changed by changing peak values of the transient currents.

The present invention is a method for producing a rare earth magnet, including preparing a magnetic powder and a modifier powder, mixing them to obtain a mixed powder, compression-molding the mixed powder in a magnetic field to obtain a magnetic-field molded body, and pressure-sintering the magnetic-field molded body to obtain a sintered body, wherein the magnetic powder includes a first particle group and a second particle group, the D.sub.50 values of the first particle group and the second particle group are denoted by d.sub.1 μm and d.sub.2 μm, respectively, d.sub.1 and d.sub.2 satisfy the relationship of 0.350≤d.sub.2/d.sub.1≤0.500, and the ratio between the total volume of the first particle group and the total volume of the second particle group is from 9:1 to 4:1; and a rare earth magnet obtained by the production method.

A sintered R.sub.2M.sub.17 magnet is provided that comprises at least 70 Vol % of a Sm.sub.2M.sub.17 phase, wherein R is at least one of the group consisting of Ce, La, Nd, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm,

Yt, Lu and Y, and M comprises Co, Fe, Cu and Zr. In an area of the R.sub.2M.sub.17 sintered magnet of 200 by 200 μm viewed in a Kerr micrograph, an areal proportion of demagnetised regions after application of an internal opposing field of 1200 kA/m is less than 5% or less than 2%.

The present disclosure aims to provide a bonded magnet having good magnetic properties and a method of preparing the bonded magnet. The present disclosure provides a method of preparing a bonded magnet, including: a first compression step of compressing a magnetic powder having an average particle size of 10 .Math.m or less while magnetically orienting it to obtain a first molded article; a second compression step of bringing the first molded article into contact with a thermosetting resin having a viscosity of 200 mPa.Math.s or less, followed by compression to obtain a second molded article; and a heat treatment step of heat treating the second molded article.