A permanent magnet includes R and T (R essentially includes Sm one or more of rare earth elements in addition to Sm, and T essentially includes Fe, or Fe and Co, one or more of transition metal elements in addition to Fe, or Fe and Co). A composition ratio of R in the permanent magnet is 20 at % or more and 40 at % or less. A remaining part is substantially only T, or only T and C. T amount is more than 1.5 times of R amount and less than 4.0 times of the R amount. Main phase grains included in the permanent magnet have an Nd5Fe17 type crystal structure. An average crystal grain size of the main phase grains of the permanent magnet is greater than 1 μm. A number ratio of main phase grains having a crystal grain size of less than 0.4 μm is less than 20%.

The present invention relates to a method for preparing a neodymium-iron-boron rare-earth permanent magnetic material, in particular to a hot press molding-based method for preparing a rare-earth permanent magnet. The problem that the residual magnetism and coercive force of a rare-earth permanent magnet prepared in the prior art cannot be both high is solved. An RTM alloy infiltrates same during an HD treatment. RTM sticks to the surface of coarse powder and infiltrates into the interior of the coarse powder along a grain boundary. The temperature of hot press sintering is relatively low, and grains barely grow. In the absence of Dy and Tb, a higher coercive force is obtained. If an alloy containing Dy and Tb is used for infiltration, these atoms diffuse into the surface layer of a main phase during preheating and heat treatment, achieving grain boundary hardening. Under the premise of a very small reduction in the residual magnetism, the coercive force is greatly improved.

To provide an R—Fe—B-based rare earth magnet excellent in the squareness and magnetic properties at high temperatures, and a production method thereof.

The present disclosure provides a rare earth magnet including a main phase 10 and a grain boundary phase 20 present. The overall composition of the rare earth magnet of the present disclosure is represented, in terms of molar ratio, by the formula: (R.sup.1.sub.(1-x)La.sub.x).sub.y(Fe.sub.(1-z)Co.sub.z).sub.(100-y-w-v)B.sub.wM.sup.1.sub.v, wherein R.sup.1 is one or more predetermined rare earth elements, and M.sup.1 is one or more predetermined elements, and wherein 0.02≤x≤0.1, 12.0≤y≤20.0, 0.1≤z≤0.3, 5.0≤w≤20.0, and 0≤v≤2.0. The main phase 10 has an R.sub.2Fe.sub.14B-type crystal structure, the average particle diameter of the main phase 10 is from 1 to 10 μm, and the volume ratio of a phase having an RFe.sub.2-type crystal structure in the grain boundary phase 20 is 0.60 or less relative to the grain boundary phase 20.

An anisotropic bonded magnet and a preparation method thereof are provided. By stacking magnets having different magnetic properties and/or densities, the magnets in the middle have high properties and the magnets at two ends and/or the periphery have low properties, thereby compensating for a property deviation caused by a difference in pressing densities during a pressing process, and improving the property uniformity of the magnets in an axial direction. The method solves the problem of “low in the middle and high at two ends” caused by the phenomenon of non-uniform magnetic field orientation and density along a height direction during orientation and densification.

The present disclosure is directed to methods of preparing substantially spherical metallic alloyed particles, having micron and sub-micron (i.e., nanometer)-scaled dimensions, and the powders so prepared, as well as articles derived from these powders. In particular embodiments, these metallic alloyed particles, complising rare earth metals, can be prepared in sizes as small 80 nm in diameter with size variances as low as 2-5%.

A magnet and a method of forming the magnet are provided. The method includes forming a slurry comprising magnetic powder material and binder material and creating raw layers from the slurry. A magnetic field is applied to the raw layers to orient the magnetic powder material in a desired direction, and each layer is cured to form another layer on the most recent cured layer. The layers are attached together.

An R-T-B based permanent magnet includes a rare earth element R, a transition metal element T, and B. The permanent magnet includes at least Nd as R. The permanent magnet includes at least Fe as T. The permanent magnet contains main phase grains and R-rich phases. The main phase grains include at least R, T, and B. The R-rich phases include at least R. The main phase grains observed in a cross section of the permanent magnet are flat. The cross section is parallel to an easy magnetization axis direction of the permanent magnet. Each of the R-rich phases is located between the main phase grains. An average value of intervals between the R-rich phases in the easy magnetization axis direction is from 5 μm to a width of the permanent magnet in the easy magnetization axis direction.

A rare-earth magnet and a method of manufacturing the same are provided. The method includes: preparing Sm-Fe-N magnetic powder; preparing reforming material powder containing metallic zinc; mixing the magnetic powder and the reforming material powder to obtain mixed powder; subjecting the mixed powder to compression molding in a magnetic field to obtain a magnetic-field molded body; subjecting the magnetic-field molded body to pressure sintering to obtain a sintered body; and subjecting the sintered body to heat treatment. A content proportion of the metallic zinc in the reforming material powder is 10 to 30% by mass with respect to the mixed powder. When a temperature and time in conditions for the heat treatment are defined as x° C. and y hours, respectively, the formulas y≥−0.32x+136 and 350≤x≤410 are met.

The disclosure refers to a preparation method for NdFeB permanent magnet including:

a) Preparing main alloy flakes consisting of (Pr.sub.2Nd.sub.8).sub.xFe.sub.100-x-y-zB.sub.yM.sub.z,where M is at least one of Al,Co,Cu,Ga,Ti and Zr, 28.5 wt. % ≤x≤31.0 wt. %,0.85 wt. %≤y≤0.98 wt. % and 0.5 wt. %≤z≤5.0 wt. %;

b) Preparing auxiliary alloy flakes consisting of L.sub.uFe.sub.100-u-v-wB.sub.vM.sub.w,where L is at least one ofPr and Nd,M is at least one of Al,Co,Cu,Ga,Ti and Zr, 35.0 wt. %≤u≤45.0 wt. %,0 wt. %≤v≤5.0 wt. % and 2.0 wt. %≤w≤10.0 wt. %;

c) Mixing the main alloy flakes and the auxiliary alloy flakes in predetermined rate, then performing hydrogen decrepitation to produce alloy pieces,and then crushing the alloy pieces to alloy powder by jet milling;

d) Preparing a powder mixture including the alloy powder and added heavy rare earth powder consisting of at least one of Dy and Tb;

e) Pressing the powder mixture to a green compact while applying a magnetic field, and thermal treatment of the green compact in a vacuum furnace to obtain the NdFeB permanent magnet.

A method of producing a magnetic powder and a magnetic powder is provided. The method of producing a magnetic powder according to an exemplary embodiment of the present disclosure includes: producing an iron powder by a reduction reaction of iron oxide, producing a magnetic powder using a molded body obtained by press molding a mixture including the iron powder, a rare earth oxide, boron, and calcium at a pressure of 22 MPa or more, and coating a surface of the magnetic powder with ammonium fluoride.