A rare earth sintered magnet is prepared by a method comprising the steps of melting raw materials to form an alloy, pulverizing the alloy into a fine powder, shaping the fine powder into a compact, and sintering the compact. The pulverizing step includes a coarse pulverizing step including hydrogen decrepitation and a fine pulverizing step, and further includes the step of adding a lubricant. The sintering step includes an atmosphere heat treatment including heating the compact at a temperature from the lubricant decomposition temperature to the sintering temperature and holding at the temperature for a time, in an inert gas atmosphere, and a vacuum heat treatment. The sintered magnet has a low impurity concentration and a narrow carbon concentration distribution.

When a slurry s obtained by dispersing a rare-earth-compound powder in a solvent is applied to sintered magnet bodies m, and dried to remove the solvent in the slurry and cause the surfaces of the sintered magnet bodies to be coated with the powder, and the sintered magnet bodies coated with the powder are heat treated to cause the rare-earth element to be absorbed by the sintered magnet bodies, the sintered magnet bodies m are warmed or heated before the slurry s is applied. As a result, the rare-earth-compound powder can be efficiently and uniformly applied to the surfaces of the sintered magnet bodies.

The present disclosure relates to a method for preparing high-performance sintered NdFeB magnets. The method comprises the steps of: a) attaching a multi-element alloy powder onto a surface of the sintered NdFeB magnet, wherein the multi-element alloy is of formula (1) Pr.sub.aRH.sub.bGa.sub.cCu.sub.d (1) with RH being at least one element selected from Dy and Tb and a, b, c, and d satisfying the conditions 0.30≤(a+b)/(a+b+c+d)≤0.65, 0.20≤d/(c+d)≤0.50, and 0.23≤b/(a+b)≤0.60; and b) performing a diffusion process.

A sintered R.sub.2M.sub.17 magnet is provided that comprises at least 70 Vol % of a Sm.sub.2M.sub.17 phase, wherein R is at least one of the group consisting of Ce, La, Nd, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm,

Yt, Lu and Y, and M comprises Co, Fe, Cu and Zr. In an area of the R.sub.2M.sub.17 sintered magnet of 200 by 200 μm viewed in a Kerr micrograph, an areal proportion of demagnetised regions after application of an internal opposing field of 1200 kA/m is less than 5% or less than 2%.

A production method of a Sm—Fe—N-based rare earth magnet, enabling to stably impart sufficient anisotropy, is provided.

The present disclosure provides a production method of a rare earth magnet, including preparing a raw material powder containing a magnetic powder (SmFeN powder 10) having a magnetic phase which contains Sm, Fe and N and at least partially has a crystal structure of at least either Th.sub.2Zn.sub.17 type or Th.sub.2Ni.sub.17 type, and pressure-sintering the raw material powder. In this production method, magnetic orientation is imparted to the raw material powder by applying a magnetic field before the pressure sintering, and the application of magnetic field is continued to maintain the magnetic orientation at least until the middle of the pressure sintering.

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.

A magnetic field generator including: a yoke; and a plurality of main magnetic pole magnets and a plurality of secondary magnetic pole magnets, the main magnetic pole magnets and the secondary magnetic pole magnets comprising a rare earth sintered magnet, having magnetic pole orientations different from each other by substantially 90°, and being alternately arranged in a linear Halbach magnet array without gaps and fixed to the yoke, wherein near contact surfaces of the main magnetic pole magnets and the secondary magnetic pole magnets, a grain boundary diffusion layer is formed in which at least one of Dy or Tb being heavy rare earth elements or a compound of at least one of the Dy or the Tb is diffused into internal grain boundaries from the contact surfaces.

A sintered R.sub.2M.sub.17 magnet is provided that comprises at least 70 Vol % of a Sm.sub.2M.sub.17 phase, wherein R is at least one of the group consisting of Ce, La, Nd, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm,

Yt, Lu and Y, and M comprises Co, Fe, Cu and Zr. In an area of the R.sub.2M.sub.17 sintered magnet of 200 by 200 μm viewed in a Kerr micrograph, an areal proportion of demagnetised regions after application of an internal opposing field of 1200 kA/m is less than 5% or less than 2%.

Provided is a rare earth sintered magnet in which a multi-layer main phase particle having multiple layers including a layer 1 having R.sup.2 concentration, represented by at %, higher than that of a center of the particle, a layer 2 which is formed on the outside of the layer 1 and has R.sup.2 concentration lower than that of the layer 1, and a layer 3 which is formed on the outside of the layer 2 and has R.sup.2 concentration higher than that of the layer 2 is present at least in a portion in the vicinity of a surface of the main phase particle within at least 500 μm from a surface of the sintered magnet body.

In a sintered rare-earth magnet containing R.sub.2T.sub.14B main-phase grains (R being one or more element selected from rare-earth elements and T being one or more element selected from iron group elements), intergranular grain boundaries that from between two mutually adjoining main-phase grains and grain boundary triple junctions surrounded by three or more main-phase grains, the main-phase grains, the intergranular grain boundaries and the grain boundary triple junctions all include TiB.sub.2 crystals. The sintered rare-earth magnet is a to high-performance magnet of high coercivity and good squareness.