The present invention discloses a grain boundary diffusion method of an R—Fe—B series rare earth sintered magnet, an HRE diffusion source, and a preparation method thereof, comprising the following steps: engineering A of forming a dry layer on a high-temperature-resistant carrier, the dry layer being adhered with HRE compound powder, the HRE being at least one of Dy, Tb, Gd, or Ho; and engineering B of performing heat treatment on the R—Fe—B series rare earth sintered magnet and the high-temperature-resistant carrier treated with the engineering A in a vacuum or inert atmosphere and supplying HRE to a surface of the R—Fe—B series rare earth sintered magnet. The method can reduce the consumption of heavy rare earth element and control the loss of residual magnetism Br while increasing the coercivity.

A high-performance Nd—Fe—B isotropic magnetic powder and a preparation method thereof are disclosed. The method includes S1, smelting and refining ingredients under vacuum to obtain an alloy ingot, crushing the alloy ingot to obtain an alloy block, wherein the smelting is conducted at a temperature of 1,350-1,450° C., and the refining is conducted at a temperature of 1,335-1,430° C. and a pressure of 900-1,100 Pa in an inert gas atmosphere for 3-7 minutes; S2, melting the alloy block obtained in step S1 to obtain an alloy solution, rapidly quenching the alloy solution to form a Nd—Fe—B rapidly-quenched alloy plate; S3, crushing the Nd—Fe—B rapidly-quenched alloy plate obtained in step S2 to obtain a magnetic powder; S4, subjecting the magnetic powder to a crystallization heat treatment in an inert gas atmosphere, and cooling to obtain the Nd—Fe—B isotropic magnetic powder.

A method for manufacturing a multicomponent permanent magnet, and a multicomponent permanent magnet are proposed. The multicomponent permanent magnet has a first permanent magnet having a R-T-B-composition, wherein R is at least one selected from the group consisting of Y, Ce, La, Pr, Nd, Sm, Eu and Gd and T is one or more transition metal elements including Fe; and a second permanent magnet having a R-T-B-composition, wherein R is at least one selected from the group consisting of Y, Ce, La, Pr, Nd, Sm, Eu and Gd and T is one or more transition metal elements including Fe, the second magnet including at least one of a heavy rare earth element (HRE) and an increased amount of Ce and/or Co, the second magnet having different magnetic properties, in particular a higher coercivity, than the first magnet. The first magnet and the second magnet are connected mechanically, wherein the connection is electrically conductive with an adjusted electrical resistivity.

A permanent magnet of an embodiment comprises: a base magnet represented by a-b-c (a includes a rare earth-based element, b includes a transition element, and c includes boron (B)); and a coating layer coated on a surface of the base magnet, wherein the coating layer comprises a compound containing a metal having magnetism, the compound including: a phosphor (P); and a metal belonging to the fourth period in the periodic table.

A magnet material is represented by a formula: R.sub.xD.sub.yBe.sub.sB.sub.tM.sub.100-x-y-t (R is at least one element selected from a group consisting of rare-earth elements, D is at least one element selected from a group consisting of Nb, Ti, Zr, Ta, and Hf, and M is at least one element selected from a group consisting of Fe and Co, and when a total number of elements obtained by adding R, D, B, and M is set to 100, x is a number satisfying 4.0<x≤11.0, y is a number satisfying 0≤y≤7.5, s is a number satisfying 0<s 1.0, and t is a number satisfying 0≤t<12), and includes a main phase having at least one crystal phase selected from a group consisting of a ThMn.sub.12 type crystal phase and a TbCu.sub.7 type crystal phase.

To provide a motor control method ensuring that dragging loss at the time of high rotation can be reduced. A motor control method, wherein a composite permanent magnet has a core part and a shell part, the Curie temperature of one of the core part and the shell part is T.sub.c1 K, and the Curie temperature of another is T.sub.c2 K, and wherein when the magnitude of the reluctance torque is equal to or greater than the magnitude of the magnet torque, the temperature of the composite permanent magnet is set at T.sub.s K that is (T.sub.c1100) K or higher and lower than T.sub.c2 K and when the magnitude of the reluctance torque is less than the magnitude of the magnetic torque, the temperature of the composite permanent magnet is set at lower than the temperature T.sub.s K or T.sub.c1 K, whichever is lower.

There is provided a method for manufacturing a rare earth sintered magnet to improve the high temperature demagnetization characteristic of the rare earth permanent magnet, by diffusing a heavy rare earth element to the grain boundary of a sintered magnet to improve the magnetic characteristics based on temperature.

A method for manufacturing a multicomponent permanent magnet, and a multicomponent permanent magnet are proposed. The multicomponent permanent magnet has a first permanent magnet having a R-T-B-composition, wherein R is at least one selected from the group consisting of Y, Ce, La, Pr, Nd, Sm, Eu and Gd and T is one or more transition metal elements including Fe; and a second permanent magnet having a R-T-B-composition, wherein R is at least one selected from the group consisting of Y, Ce, La, Pr, Nd, Sm, Eu and Gd and T is one or more transition metal elements including Fe, the second magnet including at least one of a heavy rare earth element (HRE) and an increased amount of Ce and/or Co, the second magnet having different magnetic properties, in particular a higher coercivity, than the first magnet. The first magnet and the second magnet are connected mechanically, wherein the connection is electrically conductive with an adjusted electrical resistivity.

To provide a motor control method ensuring that dragging loss at the time of high rotation can be reduced.

A motor control method, wherein a composite permanent magnet has a core part and a shell part, the Curie temperature of one of the core part and the shell part is T.sub.c1 K, and the Curie temperature of another is T.sub.c2 K, and wherein when the magnitude of the reluctance torque is equal to or greater than the magnitude of the magnet torque, the temperature of the composite permanent magnet is set at T.sub.s K that is (T.sub.c1100) K or higher and lower than T.sub.c2 K and when the magnitude of the reluctance torque is less than the magnitude of the magnetic torque, the temperature of the composite permanent magnet is set at lower than the temperature T.sub.s K or T.sub.c1 K, whichever is lower.

A permanent magnet of an embodiment comprises: a base magnet represented by a-b-c (a includes a rare earth-based element, b includes a transition element, and c includes boron (B)); and a coating layer coated on a surface of the base magnet, wherein the coating layer comprises a compound containing a metal having magnetism, the compound including: a phosphor (P); and a metal belonging to the fourth period in the periodic table.