An anisotropic bonded magnet and a preparation method thereof are provided. Through a method of stacking magnets which are different in content of SmFeN and/or have different 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 densities during a pressing process, and improving the property uniformity of the magnets in an axial direction. The method avoids the phenomenon of non-uniform magnetic field orientation and density in a height direction during orientation and densification as well as the phenomenon of low in the middle and high at two ends.

A two-step diffusion method for preparing high-performance dual-main-phase sintered mischmetal-iron-boron magnet belongs to the preparing technical field of rare earth permanent magnet materials. The compositions of the two main phase alloys are RE-Fe—B (RE is Nd or Pr) and (Nd, MM)-Fe—B (MM is mischmetal), respectively. First, PrHoFe strip-casting alloy is used as a diffusion source. Next, a PrHo-rich layer is uniformly coated on the surface of (Nd, MM)-Fe—B hydrogen decrepitation powders. The higher anisotropic fields of Pr.sub.2Fe.sub.14B and Ho.sub.2Fe.sub.14B are used to improve the coercivity. Then, the ZrCu strip-casting alloy is used as a diffusion source. A Zr-rich layer is uniformly coated on the surface of the powders after the first-step diffusion, which prevents the growth of the MM-rich main phase grains during the sintering process and the inter-diffusion between the two main phases, thus obtaining high coercivity.

A single crystal particle powder having a crystal structure of TbCu.sub.7-type of the present invention is represented by the general formula:

[Chemical Formula 1]

(R.sub.1-zM.sub.z)T.sub.x  (1)

or the general formula:

[Chemical Formula 2]

(R.sub.1-zM.sub.z)T.sub.xN.sub.y  (2)

and has a crystal structure of TbCu.sub.7-type,
wherein R is at least one element selected from the group consisting of Sm and Nd, T is at least one element selected from the group consisting of Fe and Co, x is 7.0≤x≤10.0, y is 1.0≤y≤2.0, and z is 0.0≤z≤0.3.

To provide an R—Fe—B-based rare earth magnet excellent in the squareness and magnetic properties at high temperatures, and method for producing thereof.

The present disclosure relates to a rare earth magnet including a main phase 10 and a grain boundary phase 20 present around the main phase 10, and a method for producing thereof. In the rare earth magnet of the present disclosure, the overall composition is represented, in terms of molar ratio, by the formula: (R.sup.1.sub.(1-x)La.sub.x).sub.y(Fe.sub.(1-z)Co.sub.z).sub.(100-y-w-v)B.sub.wM.sup.1.sub.v, wherein R.sup.1 is a predetermined rare earth element, M.sup.1 is a predetermined element, 0≤x≤0.1, 12.0≤y≤20.0, 0.1≤z≤0.3, 5.0≤w≤20.0, and 0≤v≤2.0. The main phase 10 has an R.sub.2Fe.sub.14B-type crystal structure, the average particle diameter of the main phase 10 is less than 1 μm, and the volume ratio of a phase having an RFe.sub.2-type crystal structure in the grain boundary phase 20 is 0.40 or less relative to the grain boundary phase 20.

A rare earth-iron-nitrogen-based magnetic powder according to this invention contains, as main constituent components, a rare-earth element (R), iron (Fe), and nitrogen (N). Moreover, this magnetic powder has an average particle size of 1.0-10.0 μm, and contains 22.0-30.0 mass % of a rare-earth element (R) and 2.5-4.0 mass % of nitrogen (N). Further, this magnetic powder includes: a core part having any one crystal structure among a Th.sub.2Zn.sub.17 type, a Th.sub.2Ni.sub.17 type, and a TbCu.sub.7 type; and a shell layer provided on the surface of the core part and having a thickness of 1-30 nm. The shell layer contains a rare-earth element (R) and iron (Fe) so that the R/Fe atomic ratio is 0.3-5.0, and further contains 0-10 at % (exclusive of 0) of nitrogen (N). Furthermore, this magnetic powder contains compound particles composed of a rare-earth element (R) and phosphorus (P).

Provided are a method of producing a titanium-containing rare earth-iron-nitrogen anisotropic magnetic powder having good magnetic properties, and secondary particles for a titanium-containing anisotropic magnetic powder. The method includes: obtaining a first precipitate containing R, iron, and titanium by mixing a first precipitating agent with a solution containing R, iron, and titanium, wherein R is at least one selected from Sc, Y, Pr, Nd, Pm, Sm, Gd, Tb, Dy, Ho, Er, Tm, and Lu; obtaining a second precipitate containing R and iron by mixing, in the presence of the first precipitate, a second precipitating agent with a solution containing R and iron; obtaining an oxide containing R, iron, and titanium by calcining the second precipitate; obtaining a partial oxide by heat treating the oxide in a reducing gas atmosphere; obtaining alloy particles by reducing the partial oxide; and obtaining an anisotropic magnetic powder by nitriding the alloy particles.

The present disclosure provides a method for manufacturing a multi-main-phase structure magnet having excellent coercive force and a multi-main-phase structure magnet manufactured therefrom.

Example nanoparticles may include an iron-based core, and a shell. The shell may include a non-magnetic, anti-ferromagnetic, or ferrimagnetic material. Example alloy compositions may include an iron-based grain, and a grain boundary. The grain boundary may include a non-magnetic, anti-ferromagnetic, or ferrimagnetic material. Example techniques for forming iron-based core-shell nanoparticles may include depositing a shell on an iron-based core. The depositing may include immersing the iron-based core in a salt composition for a predetermined period of time. The depositing may include milling the iron-based core with a salt composition for a predetermined period of time. Example techniques for treating a composition comprising core-shell nanoparticles may include nitriding the composition.

The disclosed technology provides a nanofunctionalized magnetic material feedstock comprising: from 50 wt % to 99.5 wt % of magnetic microparticles having an average microparticle effective diameter from 1 micron to 500 microns; from 0.4 wt % to 40 wt % of one or more rare earth elements; and from 0.1 wt % to 10 wt % of metal-containing inoculant nanoparticles, wherein at least 1 wt % of the inoculant nanoparticles are chemically and/or physically disposed on surfaces of the magnetic microparticles. The nanofunctionalized magnetic material feedstock is processed using high-throughput laser-based additive manufacturing to optimize the architecture of NdFeB or other magnets, generating site-specific, demagnetization-resistant microstructures. This disclosure teaches a rapid, single-step laser-based process to tailor the easy axis alignment, grain size, and microstructure of a permanent magnet at corners and edges to resist demagnetization.

The disclosed technology provides a cladded permanent magnet comprising: a core magnet region containing a core magnetic material; and a magnet cladding containing a shell magnetic material comprising (i) a magnetic compound that is chemically the same as the core magnetic material, (ii) one or more rare earth elements, and (iii) metal-containing inoculant nanoparticles, wherein the magnet cladding is disposed on the core magnet region, wherein the magnet cladding has at least 10% higher ambient-temperature magnetic coercivity compared to the core magnet region. The cladded permanent magnet is made via high-throughput laser-based additive manufacturing to optimize the architecture of NdFeB or other magnets, generating site-specific, demagnetization-resistant microstructures. This disclosure teaches a rapid, single-step laser-based process to tailor the easy axis alignment, grain size, and microstructure of a permanent magnet at corners and edges to resist demagnetization.