The disclosure discloses a NdFeB permanent magnet and a preparation method thereof. The magnet is composed of main phase I, a shell structure, a grain boundary phase adjacent to the shell structure, a main phase II, a Ga rich region and a Cu rich region. The magnet has high remanence, high coercivity, and high magnetic energy. In addition, this method can significantly reduce the production cost.

The present disclosure is directed towards a method of manufacturing a permanent magnet such that the magnet defines a channel for allowing circulation of a coolant through the permanent magnet, or defines a channel for allowing circulation of the coolant through an interface between the permanent magnet and a substrate. Magnets made by this method may be useful for manufacturing and/or operating a machine, such as a motor, engine, or sensor.

The present invention provides a rare-earth sintered magnet that is characterized in that: R (R indicates one or more elements selected from rare-earth elements, wherein Nd is essential), T (T indicates one or more elements selected from iron-group elements, wherein Fe is essential), X (X indicates one or two elements selected from B and C, wherein B is essential), M.sup.1 (M.sup.1 indicates one or more elements selected from Al, Si, Cr, Mn, Cu, Zn, Ga, Ge, Mo, Sn, W, Pb, and Bi), 0.1 mass % or less of O, 0.05 mass % or less of N, and 0.07 mass % or less of C are contained; the average crystal grain size is 4.0 μm or less; and relational expression (1) 0.26×D+97≤Or≤0.26×D+99 is satisfied assuming that the degree of orientation is Or [%] and that the average crystal grain size is D [μm]. With this rare-earth sintered magnet, it is possible to achieve superior magnetic characteristics in which both high Br and high H.sub.cJ are achieved.

The present disclosure relates generally to a method for improving the performance of sintered NdFeB magnet. A method of preparing a sintered NdFeB magnet therefore comprises the steps of: a) preparing alloy flakes from a raw material of the NdFeB magnet by a strip casting process; and b) preparing a coarse alloy powder from the alloy flakes by a hydrogen decrepitation process, the hydrogen decrepitation process including treatment of the alloy flakes under a hydrogen pressure of 0.10 MPa to 0.25 MPa for a duration of 1 to 3.5 hours, then degassing the hydrogen at a predetermined temperature between 300° C. to 400° C. for a duration time of 0.5 to 5 hours, and then mixing the resulting coarse alloy powder with a lubricant.

An R-T-B-based sintered magnet and a preparation method therefor. The R-T-B-based sintered magnet comprises: R, B, Ti, Ga, Al, Cu, and T. The contents thereof are as follows: R is 29.0-33%; the content of B is 0.86-0.93%; the content of Ti is 0.05-0.25%; the content of Ga is 0.3-0.5%, but not 0.5%; the content of Al is 0.6-1%, but not 0.6%; the content of Cu is 0.36-0.55%. The percentage is the mass percentage. Under the condition that no heavy rare earth is added or a small amount of heavy rare earth is added, by using a low B technology, not only the remanence performance of the R-T-B-based sintered magnet is improved, but also the coercivity and the squareness of the magnet are ensured.

A neodymium-iron-boron permanent magnet material, a preparation method, and an application. The neodymium permanent magnet material includes R, Al, Cu, and Co; R comprises RL and RH; RL comprises one or many light rare earth elements among Nd, La, Ce, Pr, Pm, Sm, and Eu; RH comprises one or many heavy rare earth elements among Tb, Gd, Dy, Ho, Er, Tm, Yb, Lu, and Sc; the neodymium-iron-boron permanent magnet material satisfies the following relations: (1) B/R: 0.033-0.037; (2) AI/RH: 0.12-2.7. The neodymium-iron-boron permanent magnet material has uniquely advantageous magnetic and mechanical properties, with Br≥13.12 kGs, Hcj≥17.83 kOe, and bending strength≥409 MPa.

Disclosed are a neodymium-iron-boron magnet material, a raw material composition, a preparation method therefor and a use thereof. The raw material composition of the neodymium-iron-boron magnet material comprises the following components in weight content: R: 28-33%; R being rare earth elements, and comprising R1 and R2, R1 being a rare earth element added during smelting, R1 comprising Nd and Dy, R2 being a rare earth element added during grain boundary diffusion, R2 comprising Tb, and the content of R2 being 0.2-1%; M: ≤0.4% but not 0, M being one or more elements among Bi, Sn, Zn, Ga, In, Au and Pb; Cu: ≤0.15% but not 0; B: 0.9-1.1%; Fe: 60-70%; but not containing Co. The neodymium-iron-boron magnet material under the condition of adding a small amount of heavy rare earth elements and not adding cobalt, can still have a relatively high coercivity and remanence, and excellent thermal stability.

An R-T-B based permanent magnet including R.sub.2T.sub.14B main phase crystal grains and a grain boundary. R represents one or more rare earth elements, T represents one or more iron group elements essentially including Fe or Fe and Co, and B represents boron. In a cross-section parallel to the alignment direction of the R-T-B based permanent magnet, the coverage of the R.sub.2T.sub.14B main phase crystal grains is 50.0% or more, and the area ratio of the R.sub.2T.sub.14B main phase crystal grains is 92.0% or more.

A neodymium-iron-boron permanent magnet, a preparation method and use thereof are disclosed. The neodymium-iron-boron permanent magnet has a composition represented by formula I: [mHR(1−m) (Pr.sub.25Nd.sub.75)].sub.x(Fe.sub.100-a-b-c-dM.sub.aGa.sub.bIn.sub.cSn.sub.d).sub.100-x-yB.sub.y formula I; where a is 0.995-3.493, b is 0.114-0.375, c is 0.028-0.125, d is 0.022-0.100; x is 29.05-30.94, y is 0.866-1.000; m is 0.02-0.05; HR is Dy and/or Tb; M is at least one selected from the group consisting of Co, Cu, Ti, Al, Nb, Zr, Ni, W and Mo.

The present invention relates to an R-T-B sintered magnet and a preparation method thereof. The sintered magnet includes a grain boundary region T1, a shell layer region T2 and an R.sub.2Fe.sub.14B grain region T3; at 10 μm to 60 μm from a surface of the sintered magnet toward a center thereof, an area ratio of the shell layer region T2 to the R.sub.2Fe.sub.14B grain region T3 is 0.1 to 0.3, and a thickness of the shell layer region T2 is 0.5 μm to 1.2 μm; and an average coating percent of the shell layer region T2 on the R.sub.2Fe.sub.14B grain region T3 is 80% or more. In the present invention, by optimizing a preparation process and a microstructure of a traditional rare earth permanent magnet, diffusion efficiency of heavy rare earth in the magnet is improved, such that coercivity of the magnet is greatly improved, and manufacturing cost is reduced.