A sintered magnet body (R.sub.aT.sup.1.sub.bM.sub.cB.sub.d) coated with a powder mixture of an intermetallic compound (R.sup.1.sub.iM.sup.1.sub.j, R.sup.1.sub.xT.sup.2.sub.yM.sup.1.sub.z, R.sup.1.sub.iM.sup.1.sub.jH.sub.k), alloy (M.sup.1.sub.dM.sup.2.sub.e) or metal (M.sup.1) powder and a rare earth (R.sup.2) oxide is diffusion treated. The R.sup.2 oxide is partially reduced during the diffusion treatment, so a significant amount of R.sup.2 can be introduced near interfaces of primary phase grains within the magnet through the passages in the form of grain boundaries. The coercive force is increased while minimizing a decline of remanence.

Disclosed are a stirring process and a stirring system for a neodymium-iron-boron powder and a process for manufacturing a neodymium-iron-boron magnetic steel. The stirring process for the neodymium-iron-boron powder mainly comprises the following aeration, feeding and stirring. Specifically, the aeration refers to filling a mixer with nitrogen and/or an inert gas, with the internal space of the mixer closed; the feeding refers to placing a neodymium-iron-boron powder to be stirred into the mixer and keeping the internal space of the mixer closed; and the stirring refers to introducing the mixer with a pulsed air stream, which is an intermittently jetted air stream formed by nitrogen and/or an inert gas, and by which the neodymium-iron-boron powder can be repeatedly blown up and down to mix and stir the neodymium-iron-boron powder.

Disclosed are a stirring process and a stirring system for a neodymium-iron-boron powder and a process for manufacturing a neodymium-iron-boron magnetic steel. The stirring process for the neodymium-iron-boron powder mainly comprises the following aeration, feeding and stirring. Specifically, the aeration refers to filling a mixer with nitrogen and/or an inert gas, with the internal space of the mixer closed; the feeding refers to placing a neodymium-iron-boron powder to be stirred into the mixer and keeping the internal space of the mixer closed; and the stirring refers to introducing the mixer with a pulsed air stream, which is an intermittently jetted air stream formed by nitrogen and/or an inert gas, and by which the neodymium-iron-boron powder can be repeatedly blown up and down to mix and stir the neodymium-iron-boron powder.

An R-T-B-based permanent magnet which contains R that represents at least one rare earth element essentially including Tb or Dy, T that represents Fe or at least one iron-group element essentially including Fe and Co, and B that represents boron, and further contains Cu. The total content of R is 28.35 to 29.95% by mass, inclusive, the content of Cu is 0.05 to 0.40% by mass, inclusive, and the content of B is 0.93 to 1.00% by mass, inclusive. The distribution of the concentration of Tb or Dy decreases from the outside of the R-T-B-based permanent magnet toward the inside of the R-T-B-based permanent magnet.

Disclosed are a neodymium-iron-boron magnet material, a raw material composition, a preparation method therefor and a use thereof. The raw material composition of the neodymium-iron-boron magnet material comprises the following components by mass percentage: 29.5-32% of R′, wherein R′ is a rare earth element and includes Pr and Nd; and Pr≥17.15%; 0.25-1.05% of Ga; 0.9-1.2% of B; and 64-69% of Fe. Without adding a heavy rare earth element to the neodymium-iron-boron magnet material, the remanence and coercive force of the resulting neodymium-iron-boron magnet material are both relatively high.

Disclosed herein are systems and methods for synthesis of spheroidized metal or metal alloy powders using microwave plasma processing. In some embodiments, the metal or metal alloy may comprise a highly ductile, soft, and/or malleable metal or metal alloy such that machining of the metal or metal alloy is difficult or impossible. In some embodiments, a volatile material is dispersed within the metal or metal alloy feedstock to enable machining and pre-processing of the feedstock. In some embodiments, the dispersed volatile material alters the physical properties of the feedstock, such that the metal or metal alloy, which is difficult to machine due to high ductility, softness, and/or malleability, is easily machined in a pre-processing step. In some embodiments, the pre-processed feedstock, can be fed into a plasma processing apparatus. In some embodiments, the volatile material dispersed within the feedstock material may be vaporized upon exposure to the microwave plasma apparatus. In some embodiments, plasma processing of the pre-processed feedstock material may synthesize pure, spheroidized metal or metal alloy particles, with substantially no contamination of the volatile material ion the final product.

Disclosed herein are systems and methods for synthesis of spheroidized metal or metal alloy powders using microwave plasma processing. In some embodiments, the metal or metal alloy may comprise a highly ductile, soft, and/or malleable metal or metal alloy such that machining of the metal or metal alloy is difficult or impossible. In some embodiments, a volatile material is dispersed within the metal or metal alloy feedstock to enable machining and pre-processing of the feedstock. In some embodiments, the dispersed volatile material alters the physical properties of the feedstock, such that the metal or metal alloy, which is difficult to machine due to high ductility, softness, and/or malleability, is easily machined in a pre-processing step. In some embodiments, the pre-processed feedstock, can be fed into a plasma processing apparatus. In some embodiments, the volatile material dispersed within the feedstock material may be vaporized upon exposure to the microwave plasma apparatus. In some embodiments, plasma processing of the pre-processed feedstock material may synthesize pure, spheroidized metal or metal alloy particles, with substantially no contamination of the volatile material ion the final product.

A method for producing a powdered starting material, which is provided for production of rare earth magnets, including includes the following steps: pulverizing an alloy, including at least one rare earth metal, wherein a powdered intermediate product is formed from the alloy including the at least one rare earth metal, and carrying out at least one classification aimed at particle size and/or particle density for the powdered intermediate product. A fraction of the powdered intermediate product, which is formed by the at least one classification, is used for fabrication of rare earth magnets. Furthermore, at least one dynamic classifier is provided, implementing at least one classification directed at particle size and/or particle density for the powdered intermediate product and thereby separates the fraction from the powdered intermediate product, which forms the starting material for manufacturing rare earth magnets.

An R-T-B based sintered magnet containing a first heavy rare earth element, in which R includes Nd, T includes Co and Fe, the first heavy rare earth element includes Tb or Dy, the R-T-B based sintered magnet has a region in which a concentration of the first heavy rare earth element decreases from the surface toward the inside, a first grain boundary phase which contains the first heavy rare earth element and Nd but does not contain Co is present in one cross section including the region, and an area occupied by the first grain boundary phase in one cross section including the region is 1.8% or less.

A method for producing nanoparticulate compressed tablets/pellets from synthetic and/or natural materials, and compressed tablets/pellets produced using the method for producing nanoparticulate compressed tablets/pellets from synthetic and/or natural materials and to uses thereof.