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.

Proposed are a method of manufacturing an anisotropic rare-earth bulk magnet, the method being capable of suppressing formation of ReFe.sub.2 phase, and an anisotropic rare-earth bulk magnet having excellent magnetic properties.

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.

Provided are a rare earth magnet precursor having a roughened structure on a surface or a rare earth magnet molded body having a roughened structure on a surface, and a method for manufacturing the same. In the rare earth magnet precursor or the rare earth magnet molded body, recesses and protrusions are formed on the surface having the roughened structure, and the recesses and protrusions satisfy at least one of the following (a) to (c): (a) an arithmetic mean height (Sa) (ISO 25178) from 5 to 300 μm, (b) a maximum height (Sz) (ISO 25178) from 50 to 1500 μm, and (c) a developed interfacial area ratio (Sdr) (ISO 25178) from 0.3 to 12.

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.

A manufacturing method of a sintered magnet is described. The method includes forming a pre-sintering body from a first magnetic powder and a second magnetic powder (containing a heavy rare earth element, HRE) so that at least part of the second magnetic powder is provided at at least one inner portion of the pre-sintering body and surrounded format least two opposite sides by the first magnetic powder; sintering the pre-sintering body; and annealing the sintered pre-sintering body at an annealing temperature lower than the sintering temperature, thereby causing inter-grain diffusion of HRE from the HRE reservoir zone to the grain boundary phase. After the annealing, the grain boundary phase contains the HRE in a higher concentration than the main phase.

(Co)polymer matrix composites including a porous (co)polymeric network; a multiplicity of thermally-conductive particles and a multiplicity of magnetic particles distributed within the (co)polymeric network structure; wherein the thermally-conductive particles, magnetic particles and optional magnetic particles are present in a range from 15 to 99 weight percent, based on the total weight of the particles and the (co)polymer (excluding the solvent). Methods of making and using the (co)polymer matrix composites are also disclosed. The (co)polymer matrix composites are useful, for example, as heat dissipating or heat absorbing thermal interface materials that also provide magnetic properties useful, for example, in flux field directional materials or shielding from electromagnetic interference.

An alloy cast strip preparation method includes a melting process and a casting cooling process. The melting process includes controlling a power of an induction melting furnace to perform a cyclic heat treatment to completely melt an alloy raw material before a surface temperature of a melt obtained by melting the alloy raw material is raised to 1300° C., and, after the alloy raw material is melted, adjusting the power of the induction melting furnace to stabilize the surface temperature of the melt at a temperature in a range from 1400° C. to 1500° C. The casting cooling process includes performing casting cooling on the melt arranged on a surface of a rotary cooling roll to obtain an alloy cast strip while controlling a surface linear velocity of the rotary cooling roll to be from 1.5 m/s to 2.25 m/s.