A step of, while a powder of an RLM alloy (where RL is Nd and/or Pr; M is one or more elements selected from among Cu, Fe, Ga, Co, Ni and Al) which is produced through atomization and a powder of an RH compound (where RH is Dy and/or Tb) are present on the surface of a sintered R-T-B based magnet, performing a heat treatment at a sintering temperature of the sintered R-T-B based magnet or lower is included. The RLM alloy contains RL in an amount of 65 at % or more, and the melting point of the RLM alloy is equal to or less than the temperature of the heat treatment. The heat treatment is performed while the RLM alloy powder and the RH compound powder are present on the surface of the sintered R-T-B based magnet at a mass ratio of RLM alloy:RH compound=9.6:0.4 to 5:5.

A rotor includes at least one first permanent magnet and a second permanent magnet and has 2n (n is a natural number) magnetic poles. The at least one first permanent magnet forms part of an outer peripheral surface of the rotor and is magnetized to have polar anisotropy. The second permanent magnet is adjacent to the at least one first permanent magnet in a circumferential direction of the rotor, and has lower magnetic force than magnetic force of the at least one first permanent magnet. The second permanent magnet has 3×2n magnetic poles.

An alloy for R-T-B based permanent magnet in which R is a rare earth element, T is a combination of Fe and Co, and B is boron. R includes one or more selected from Nd, Pr, Dy, and Tb. The alloy for R-T-B based permanent magnet includes M and C. M is one or more selected from Al, Cu, Zr, and Ga. Relative to 100 mass % of the alloy for R-T-B based permanent magnet, a total content of Nd, Pr, Dy, and Tb is 28.00 mass % or more and 34.00 mass % or less, Co content is 0.05 mass % or more and 3.00 mass % or less, B content is 0.70 mass % or more and 0.95 mass % or less, C content is 0.12 mass % or more and 0.19 mass % or less, a total content of M is more than 0 mass % and 4.00 mass % or less, and Fe is a substantial balance.

The present disclosure provides a method for preparing a high-coercivity sintered NdFeB magnet. The method including the steps of: S1, Providing a NdFeB powder as a main material; S2, Vacuum coating a layer of a rare earth alloy R.sub.xH.sub.(100-x) on a surface of a metal nano-powder M to obtain an auxiliary alloy material with a core-shell structure, with R being selected from one or more of Dy, Tb, Pr, Nd, La, and Ce; H being selected from one or more of Cu, Al, and Ga; the nano-powder M being selected from one or more of Mo, W, Zr, Ti, and Nb; 0≤x≤90 wt. %; S3, Adding the auxiliary alloy material obtained by step S2 to the NdFeB powder of step S1 and mixing, then orientation pressing of the mixture to obtain a compact body; and S4, Sintering and annealing treatment of the compact body to obtain the high-coercivity sintered NdFeB magnet.

A method for manufacturing a sintered magnet according to one embodiment of the present disclosure is provided. The method includes producing an R-T-B-based magnetic powder through a reduction-diffusion method, and sintering the R-T-B-based magnetic powder, wherein R is a rare earth element, and T is a transition metal, and wherein the producing the magnetic powder includes adding a refractory metal sulfide powder to a R-T-B-based raw material.

A sintered magnet and a method for producing the same are provided. The method includes producing an R—Fe—B-based magnet powder by a reduction-diffusion method, adding a R—Al—Cu powder as a sintering agent to the R—Fe—B-based magnet powder to form a mixed powder, wherein the R—Al—Cu powder is an alloy of R, Al and Cu, and R is Nd, Pr, Dy, Tb or Ce, and sintering the mixed powder to form a sintered magnet.

A ferrite sintered magnet contains a main phase formed of ferrite having a hexagonal magnetoplumbite type crystalline structure; a first subphase containing La, Ca, and Fe, in which an atomic ratio of La is higher than that of the main phase, and the atomic ratio of La is higher than an atomic ratio of Ca; and a second subphase containing La, Ca, Si, B, and Fe, in which an atomic ratio of Ca is higher than an atomic ratio of La, an atomic ratio of B is higher than an atomic ratio of Fe, and the atomic ratio of Fe is lower than that of the main phase. An area ratio of the second subphase on a cross-sectional surface of the ferrite sintered magnet is greater than or equal to 1%.

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.

The present invention relates to a Ce-containing sintered rare earth permanent magnet with high toughness and high coercivity and a method of preparing the magnet, belonging to the technical field of rare earth permanent magnetic materials. The magnet is prepared by steps of raw material batching, strip casting, hydrogen decrepitation and jet milling, powder orientating and forming, sintering and heat treatment. The materials of the permanent magnet comprise the main phase alloy powders and the Ce added phase alloy powders, wherein the Ce added phase alloy is a magnetic phase or a non-magnetic liquid-phase alloy; and the Ce added phase alloy accounts for 5% to 30% of the total weight of the permanent magnet, and the remainder is the main phase alloy. During the jet milling stage, a certain concentration of oxygen is added into the inert gas, so that the final magnet has an oxygen content of 1500 to 2500 ppm. The Ce-containing dual-alloy magnet prepared in accordance with the present invention has high coercivity, and the intrinsic coercivity (H.sub.cj) is up to 17 to 28.73 kOe. The magnet of the present invention has good fracture toughness which is increased by 10% to 30% as compared with the conventional Nd—Fe—B sintered magnet. The magnet of the present invention can meet needs of high-end applications such as wind power generation, new energy vehicles, and the like, and greatly expands the application fields of Ce-containing magnets.

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.