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.

A permanent magnet includes a rare earth element R; a transition metal element T; and B. The permanent magnet includes Nd as R. The permanent magnet includes Fe as T. The permanent magnet contains main phase grains and R-rich phases. The main phase grains include R, T, and B. The R-rich phases include 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 a direction substantially perpendicular to the easy magnetization axis direction is from 30 μm to 1,000 μm. An average value of lengths of short axes of the main phase grains observed in the cross section is from 20 nm to 200 nm.

A permanent magnetic composition comprising the formula:

(La.sub.xM.sub.yNd.sub.1-x-y).sub.rFe.sub.vM′.sub.zCo.sub.14-v-zB.sub.w  (1)

wherein 0.1≤x<1, 11≤v≤14, 0≤y≤0.3, 0≤z≤0.5, 1.9≤r≤3, 0.1≤(x+y)<1, 11≤(v+z)≤14, and 1.0≤w≤1.1, wherein M represents one or more lanthanide elements other than La and Nd, and M′ represents one or more transition metal elements other than Fe and Co, or M′ represents one or more main group elements other than B; or the permanent magnet may be more particularly described by the formula (La.sub.xNd.sub.1-x).sub.rFe.sub.vCo.sub.14-vB.sub.w or LaNdFe.sub.12Co.sub.2B, wherein x, v, and w are defined above. Also described herein are methods for producing the permanent magnet.

Provided is an R-T-B-based magnet material alloy including an R.sub.2T.sub.14B phase which is a principal phase and R-rich phases which are phases enriched with the R, wherein the principal phase has primary dendrite arms and secondary dendrite arms diverging from the primary dendrite arms, and regions where the secondary dendrite arms have been formed constitute a volume fraction of 2 to 60% of the alloy, whereby excellent coercive force can be ensured in R-T-B-based sintered magnets even when the amount of heavy rare earth elements added to the alloy is reduced. The inter-R-rich phase spacing is preferably at most 3.0 μm, and the volume fraction of chill crystals is preferably at most 1%. Furthermore, the secondary dendrite arm spacing is preferably 0.5 to 2.0 μm, and the ellipsoid aspect ratio of R-rich phase is preferably at most 0.5.

A method for producing rare-earth magnet powder having high magnetic properties including a disproportionation step of causing hydrogen absorption and disproportionation reaction to a magnet raw material obtained by exposing a cast alloy containing a rare earth element (R), boron (B) and a transition metal (TM) to a hydrogen atmosphere having a temperature of 350 to 550 deg. C, and a recombination step of causing hydrogen desorption and recombination reaction to the magnet raw material after the disproportionation step.

Provided is a permanent magnet including a rare-earth element R (such as Nd), a transition metal element T (such as Fe), B, Zr, and Cu. The permanent magnet contains a plurality of main phase grains including Nd, T, and B, and grain boundary multiple junctions, the one grain boundary multiple junction is a grain boundary surrounded by three or more of the main phase grains, one of the grain boundary multiple junctions contains a ZrB.sub.2 crystal and an R—Cu-rich phase including R and Cu, a concentration of B in the one grain boundary multiple junction containing both the ZrB.sub.2 crystal and the R—Cu-rich phase is from 5 to 20 atomic %, a concentration of Cu in the one grain boundary multiple junction containing both the ZrB.sub.2 crystal and the R—Cu-rich phase is from 5 to 25 atomic %, and a surface layer part of the main phase grain includes at least one kind of heavy rare-earth element among Tb and Dy.

The present disclosure refers to a method of preparing a NdFeB magnet powder. The method includes a hydrogen treatment process including the steps of: a) charging NdFeB alloy flakes into a hydrogen treatment furnace, wherein the NdFeB alloy flakes include a neodymium-rich phase and a main phase; b) performing a hydrogen absorption by heating the hydrogen treatment furnace in a first stage to a temperature at which only the neodymium-rich phase undergoes a hydrogen absorption reaction, then introducing and maintaining hydrogen at a predetermined pressure until the hydrogen absorption of the neodymium-rich phase is finished, then stop heating of the hydrogen treatment furnace in a second stage, where the temperature falls to a temperature at which the main phase undergoes a hydrogen absorption reaction; and c) when the hydrogen absorption of step b) is finished, performing a vacuum dehydrogenation of the obtained coarse magnet powder.

A method of processing an anisotropic permanent magnet includes forming anisotropic flakes from a hulk magnet alloy, each of the anisotropic flakes having an easy magnetization direction with respect to a surface of the flake and combining the anisotropic flakes with a binder to form a mixture. The method further includes extruding or rolling the mixture without applying a magnetic field such that the easy magnetization directions of the anisotropic flakes align to form one or more layers having a magnetization direction aligned with the easy magnetization directions of the anisotropic flakes, and producing the anisotropic permanent magnet from the layers having the magnetization direction such that the anisotropic permanent magnet has a magnetization with. a specific orientation.

The present invention discloses rare earth-bonded magnetic powder and a preparation method therefor. The bonded magnetic powder is of a multilayer core-shell structure, and comprises a core layer and an antioxidant layer (3), wherein the core layer is formed by RFeMB, R is Nd and/or PrNd, and M is one or more of Co, Nb, and Zr; and the core layer is coated with an iron-nitrogen layer (2). In addition, the present invention also discloses the preparation method for the rare earth-bonded magnetic powder and a bonded magnet. The oxidation and corrosion of magnetic raw powder during phosphorization and subsequent treatment process are effectively prevented, thereby further improving the long-term temperature resistance and environmental tolerance of the material.

A composite permanent magnet includes at least one magnetically-hard portion formed from a compacted powder material and at least one magnetically-soft portion mixed with the at least one magnetically-hard portion. The composite permanent magnet also includes a nonmagnetic outer coating portion applied to each magnetically-soft portion to isolate the coated magnetically-soft portion from magnetically-hard portions thereby inhibiting demagnetization of the at least one magnetically-hard portion.