A reactor for forming fully coated particles having a solid core, the reactor comprises a reactor vessel which is configured to receive particles, and a gas phase coating mechanism that is configured to selectively introduce pulses of gas phase materials that form a coating on the particles. The reactor also includes a sieve (16) that is located within the reactor vessel, and a forcing means that is configured to force the particles through the sieve (16) in use. The sieve is configured to deagglomerate any particle aggregates formed in the reactor vessel upon forcing of the particles by the forcing means through the sieve.

A method for producing a sintered R-T-B based magnet includes: preparing a sintered R-T-B based magnet work (R is a rare-earth element; and T is at least one selected from the group consisting of Fe, Co, Al, Mn and Si, and contains Fe with no exception); preparing an RL-RH-B-M based alloy; and a diffusion step of performing heat treatment while at least a portion of the RL-RH-B-M based alloy is attached to at least a portion of a surface of the sintered R-T-B based magnet work. In the RL-RH-B-M based alloy, the content of RL is 50 mass % or higher and 95 mass % or lower, the content of RH is 45 mass % or lower (including 0 mass %), the content of B is 0.1 mass % or higher and 3.0 mass % is lower; and the content of M is 4 mass % or higher and 49.9 mass % or lower.

Rare earth-containing alloy flakes and a sintered magnet made of the same are provided, which alloy flakes are useful in the production of sintered magnets of which Br and HcJ may be excellent and well-balanced according to the Dy and/or Tb content. The rare earth-containing alloy flakes are R-TM-A-M-type alloy flakes which have a particular composition, and a structure having a Nd.sub.2Fe.sub.14B main phase and a boundary phase, the Fe content in the boundary phase is not more than 10 mass %, and a ratio of the total content (b) of Dy and Tb in the boundary phase to the total content (a) of Dy and Tb in the main phase is higher than 1.0, and are useful as a sintered magnet material.

Provided is a sintered magnet that is an R-T-B based sintered magnet having a region having a concentration of at least one heavy rare earth element decreasing from the surface toward the inside, in which the at least one heavy rare earth element includes at least either of Tb or Dy, R includes Nd, T includes Fe, Co, and Cu, there is a grain boundary phase containing at least either of Tb or Dy and Nd between two main phase particles, and a value obtained by subtracting a half value width of a concentration distribution curve of Cu from a half value width of a concentration distribution curve of Tb or Dy in a part including the grain boundary phase is from 10 to 20 nm.

A BÏ2212 article may be formed by mixing metallic precursor powders including bismuth, strontium, calcium and copper in an oxygen-free atmosphere, mechanically alloying the metallic precursor powders in an oxygen-free atmosphere, and heating the metallic precursor alloy according to a temperature profile. The profile may include a ramp-up stage during which the alloy is heated to a peak temperature in an oxygen-free atmosphere, a dwell stage during which the alloy is held at the peak temperature for a dwell time, and a ramp-down stage during which the alloy is cooled from the peak temperature. During at least a portion of the dwell stage, the oxygen-free atmosphere is switched to an oxygen-inclusive atmosphere, wherein the alloy is oxidized to form a superconducting oxide, which may be sintered during or after oxidation. The alloy may be formed into a shape, such as a wire, prior to oxidizing.

An iron powder and method of making an iron powder. The method includes a step of neutralizing an acidic aqueous solution containing a trivalent iron ion and a phosphorus-containing ion, with an alkali aqueous solution, so as to provide a slurry of a precipitate of a hydrated oxide, or a step of adding a phosphorus-containing ion to a slurry containing a precipitate of a hydrated oxide obtained by neutralizing an acidic aqueous solution containing a trivalent iron ion with an alkali aqueous solution. A silane compound is added to the slurry so as to coat a hydrolysate of the silane compound on the precipitate of the hydrated oxide. The precipitate of the hydrated oxide after coating is recovered through solid-liquid separation, the recovered precipitate is heated to provide iron particles coated with a silicon oxide, and a part or the whole of the silicon oxide coating is dissolved and removed.

A permanent magnet is expressed by a composition formula: R.sub.pFe.sub.qM.sub.rCu.sub.tCo.sub.100-p-q-r-t. The magnet comprises a metal structure including a main phase having a Th.sub.2Zn.sub.17 crystal phase and a grain boundary phase. The main phase includes a cell phase having the Th.sub.2Zn.sub.17 crystal phase and a Cu-rich phase. A section including a c-axis of the Th.sub.2Zn.sub.17 crystal phase has a first region in the crystal grain and a second region in the crystal grain, the first region is provided in the cell phase divided by the Cu-rich phase, the second region is provided within a range of not less than 50 nm nor more than 200 nm from the grain boundary phase in a direction perpendicular to an extension direction of the grain boundary phase, and a difference between a Cu concentration of the first region and a Cu concentration of the second region is 0.5 atomic percent or less.

A permanent magnet is expressed by a composition formula: R.sub.pFe.sub.qM.sub.rCu.sub.tCo.sub.100-p-q-r-t. The magnet comprises a metal structure including a main phase having a Th.sub.2Zn.sub.17 crystal phase and a grain boundary phase. The main phase includes a cell phase having the Th.sub.2Zn.sub.17 crystal phase and a Cu-rich phase. A section including a c-axis of the Th.sub.2Zn.sub.17 crystal phase has a first region in the crystal grain and a second region in the crystal grain, the first region is provided in the cell phase divided by the Cu-rich phase, the second region is provided within a range of not less than 50 nm nor more than 200 nm from the grain boundary phase in a direction perpendicular to an extension direction of the grain boundary phase, and a difference between a Cu concentration of the first region and a Cu concentration of the second region is 0.5 atomic percent or less.

A permanent magnet of an embodiment includes a sintered compact, the sintered compact including: a composition expressed by R.sub.pFe.sub.qM.sub.rCu.sub.sCo.sub.100-p-q-r-s, (R is at least one element selected from rare earth elements, M is at least one element selected from Zr, Ti, and Hf, 10.5≦p≦12.5 atomic %, 24≦q≦40 atomic %, 0.88≦r≦4.5 atomic %, and 3.5≦s≦10.7 atomic %); and a structure having crystal grains each composed of a main phase including a Th.sub.2Zn.sub.17 crystal phase, and a crystal grain boundary of the crystal grains. An average crystal grain diameter of the crystal grains is 50 μm or more and 100 μm or less, and a ratio of the crystal grains having a crystal grain diameter of 50 μm or more is 75% or more.

A permanent magnet of an embodiment includes a sintered compact, the sintered compact including: a composition expressed by R.sub.pFe.sub.qM.sub.rCu.sub.sCo.sub.100-p-q-r-s, (R is at least one element selected from rare earth elements, M is at least one element selected from Zr, Ti, and Hf, 10.5≦p≦12.5 atomic %, 24≦q≦40 atomic %, 0.88≦r≦4.5 atomic %, and 3.5≦s≦10.7 atomic %); and a structure having crystal grains each composed of a main phase including a Th.sub.2Zn.sub.17 crystal phase, and a crystal grain boundary of the crystal grains. An average crystal grain diameter of the crystal grains is 50 μm or more and 100 μm or less, and a ratio of the crystal grains having a crystal grain diameter of 50 μm or more is 75% or more.