A sintered magnet contains Sm—Fe—N-based crystal grains and has high coercivity; and a magnetic powder is capable of forming a sintered magnet without lowering the coercivity even if heat is generated in association with the sintering. A sintered magnet comprises a crystal phase composed of a plurality of Sm—Fe—N-based crystal grains and a nonmagnetic metal phase present between the Sm—Fe—N crystal grains adjacent to each other, wherein a ratio of Fe peak intensity I.sub.Fe to SmFeN peak intensity I.sub.SmFeN measured by an X-ray diffraction method is 0.2 or less. A magnetic powder comprises Sm—Fe—N-based crystal particles and a nonmagnetic metal layer covering surfaces of the Sm—Fe—N crystal particles.

A sintered magnet contains Sm—Fe—N-based crystal grains and has high coercivity; and a magnetic powder is capable of forming a sintered magnet without lowering the coercivity even if heat is generated in association with the sintering. A sintered magnet comprises a crystal phase composed of a plurality of Sm—Fe—N-based crystal grains and a nonmagnetic metal phase present between the Sm—Fe—N crystal grains adjacent to each other, wherein a ratio of Fe peak intensity I.sub.Fe to SmFeN peak intensity I.sub.SmFeN measured by an X-ray diffraction method is 0.2 or less. A magnetic powder comprises Sm—Fe—N-based crystal particles and a nonmagnetic metal layer covering surfaces of the Sm—Fe—N crystal particles.

A neodymium-iron-boron magnetic material, a preparation method therefor and an application thereof. The neodymium-iron-boron magnetic material comprises the following components in percentage by mass: 29.5-31.5 wt. % of R, where RH>1.5 wt. %; 0.05-0.25 wt. % of Cu; 0.42-2.6 wt. % of Co; 0.20-0.3 wt. % of Ga; 0.25-0.3 wt. % of N; 0.46-0.6 wt. % of Al, or alternatively Al is less than or equal to 0.04 wt. % but is not 0; 0.98-1 wt. % of B; and 64-68 wt. % of Fe; wherein R is a rare-earth element and comprises Nd and RH, RH is a heavy rare-earth element and comprises Tb, and a mass ratio of Tb to Co is less than or equal to 15 but is not 0. The neodymium-iron-boron magnetic material has higher Hcj and Br, and lower absolute values of temperature coefficients of Br and Hcj.

An R-T-B based permanent magnet, in which R is a rare earth element, T is Fe or a combination of Fe and Co, and B is boron, includes main phase grains made of an R.sub.2T.sub.14B crystal phase and grain boundaries formed between the main phase grains. The grain boundaries include an R—O—C—N concentrated part having higher concentrations of R, O, C, and N than that of the main phase grains. The R—O—C—N concentrated part includes a heavy rare earth element. The R—O—C—N concentrated part has a core part and a shell part covering at least part of the core part. A concentration of the heavy rare earth element in the shell part is higher than a concentration of the heavy element in the core part. A covering ratio of the shell part with respect to the core part of the R—O—C—N concentrated part is 45% or more in average.

An R-T-B based permanent magnet, in which R is a rare earth element, T is Fe or a combination of Fe and Co, and B is boron, includes main phase grains made of an R.sub.2T.sub.14B crystal phase and grain boundaries formed between the main phase grains. The grain boundaries include an R—O—C—N concentrated part having higher concentrations of R, O, C, and N than that of the main phase grains. The R—O—C—N concentrated part includes a heavy rare earth element. The R—O—C—N concentrated part has a core part and a shell part covering at least part of the core part. A concentration of the heavy rare earth element in the shell part is higher than a concentration of the heavy element in the core part. A covering ratio of the shell part with respect to the core part of the R—O—C—N concentrated part is 45% or more in average.

The current invention discloses a type of micronized powder for manufacturing sintered Neodymium magnetic material, a target type jet mill pulverization method to prepare the micronized powder, and the resulting pulverized powder. The Neodymium magnet powder created under the method is of sphericity of greater than or equal to 90% and of particle adhesion rate of less than or equal to 10%. A is the diameter of the target center, B is the diameter of the side nozzle, and C is the distance between the target center and the nozzle. The relationship amongst A, B and C is A/B=m×(C/A+B), where m ranges from 1 to 7. A velocity of the jet stream from side nozzle is between about 320 m/s to about 580 m/s.

The disclosure relates to the technical field of sintered type NdFeB permanent magnets, in particular to a low-cost rare earth magnet and manufacturing method. There is provided a method of preparing a high-coercivity, sintered NdFeB magnet including cerium comprising the following steps:

(S1) Providing alloy flakes composed of R.sub.xT.sub.(1-x-y-z)B.sub.yM.sub.z;

(S2) Mixing the alloy flakes, a low melting point powder, and a lubricant, then subjecting the mixture to a hydrogen embrittlement process followed in this order by pulverizing the process product to an alloy powder by jet milling, magnetic field orientation molding of the alloy powder to obtain a blank, sintering and aging treatment the blank;

(S3) Coating a film composed of a diffusion source of formula R1.sub.xR2.sub.yH.sub.zM.sub.1-x-y-z on the sintered NdFeB magnet; and

(S4) Performing a diffusion heat treatment, followed by aging the sintered NdFeB magnet to obtain the low-cost rare earth magnet.

Provided are a neodymium-iron-boron magnet material, raw material composition, preparation method, and application. The raw material composition of the neodymium-iron-boron magnet material comprises the following mass content components: R: 28-33%; R is a rare earth element, R comprises R1 and R2; R1 is a rare earth element added during smelting, and R1 comprises Nd and Dy; R2 is a rare earth element added during grain boundary diffusion, R2 comprises Tb, the content of R2 is 0.2%-1%; Co: <0.5%, but not 0; M: ≤0.4%, but not 0, and M is one or more of Bi, Sn, Zn, Ga, In, Au, and Pb; Cu: ≤0.15%, but not 0; B: 0.9-1.1%; Fe: 60-70%; the percentage is the mass percentage of the mass of each component to the total mass of the raw material composition. The neodymium-iron-boron magnet material has high remanence, coercivity, and good thermal stability.

Disclosed in the present invention are a heavy rare earth alloy, neodymium-iron-boron permanent magnet material, a raw material, and a preparation method. The heavy rare earth alloy comprises the following components: RH: 30-100 mas %, not including 100 mas %; X, 0-20 mas %, not including 0; B: 0-1.1 mas %; and Fe and/or Co: 15-69 mas %, RH comprising one or more heavy rare earth elements in Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Sc, and X being Ti and/or Zr. When the heavy rare earth alloy of the present invention is used as a sub-alloy to prepare the neodymium-iron-boron permanent magnet material, a high utilization rate of heavy rare earth is achieved, so that the coercivity can also be greatly improved while the neodymium-iron-boron permanent magnet material maintains high remanence.

The disclosure refers to a method for preparing NdFeB magnets including at least one of Ce and La. The method includes:

S1) Separately preparing flakes of alloy R1 and flakes of alloy R2 each by a strip casting process, wherein the alloy R1 includes at least one of La and Ce, but the alloy R2 does not include La and Ce;
S2) separately subjecting the flakes of alloy R1 and R2 to a hydrogen embrittlement process followed by pulverizing the process product to alloy powders by jet milling, wherein a ratio of the average particle sizes D50 of the powder of alloy R1 and R2 satisfied formula:

0.32≤R2/R1≤0.66;

S3) mixing the powder of alloy R1 and R2; and
S4) subjecting the mixed powders to molding and magnetic field orientation, cold isostatic pressing, sintering, and an annealing process.