A method for producing a metal powder provided on the surface thereof with a glassy thin film, wherein a glassy substance is produced in the vicinity of the surface of the metal powder by spray pyrolysis from a solution that contains a thermally decomposable metal compound and a glass precursor that produces a glassy substance that does not form a solid solution with the metal produced from the metal compound by thermal decomposition, so as to form the metal powder provided on the surface thereof with the glassy thin film. The glass precursor is prepared such that the melting temperature Tm.sub.M of the metal and the liquid phase temperature Tm.sub.G of the mixed oxide of the glassy substance satisfy the following formula (1):
−100 [° C.]≤(Tm.sub.M−Tm.sub.G)≤500 [° C.]  (1).

A method for producing a metal powder provided on the surface thereof with a glassy thin film, wherein a glassy substance is produced in the vicinity of the surface of the metal powder by spray pyrolysis from a solution that contains a thermally decomposable metal compound and a glass precursor that produces a glassy substance that does not form a solid solution with the metal produced from the metal compound by thermal decomposition, so as to form the metal powder provided on the surface thereof with the glassy thin film. The glass precursor is prepared such that the melting temperature Tm.sub.M of the metal and the liquid phase temperature Tm.sub.G of the mixed oxide of the glassy substance satisfy the following formula (1):
−100 [° C.]≤(Tm.sub.M−Tm.sub.G)≤500 [° C.]  (1).

This invention relates to a preparation method of rare earth oxide dispersion strengthened fee grain tungsten materials, the mass percent of the rare earth oxide is of 0.1-2%, and the rest ingredient is W. Weigh soluble rare earth salt and tungstate, dissolve into water to made into 50-100 g/L of rare earth salt solution and 150-300 g/L of tungstate solution, respectively. Firstly, add trace alkali in rare earth salt solution to control pH in 7-8, then add organic dispersant and stir to form evenly suspended R(OH).sub.3 particle colloid (R refers to rare earth element). Secondly pour the tungstate solution into the R(OH).sub.3colloid, add trace acid to control pH in 6-7, then add organic dispersant and stir to form tungstic acid micro particles, which wrap around the colloidal particles, forming coprecipitation coating particle colloid. Thirdly, the coprecipitation coating particle colloidal is spray-dried, forming tungsten and rare earth oxide compound precursor powder. Alter that, ultrafine or nanoscale tungsten powder with particle size of 50˜500 nm is obtained through a process of calcination subsequent with hydrogen thermal reduction. Finally, the tungsten powder is subjected to ordinary compression molding and then conventional high temperature sintering. The trace rare earth oxide dispersion strengthened high performance fine grain tungsten materials prepared by this invention, its density is close to full density (98.5% or higher), its grain size is uniform and very fine (average in 5˜10 microns), and the rare earth oxides particles evenly distribute in tungsten intracrystalline or grain, boundary with particle size of 100˜500 nm.

This invention relates to a preparation method of rare earth oxide dispersion strengthened fee grain tungsten materials, the mass percent of the rare earth oxide is of 0.1-2%, and the rest ingredient is W. Weigh soluble rare earth salt and tungstate, dissolve into water to made into 50-100 g/L of rare earth salt solution and 150-300 g/L of tungstate solution, respectively. Firstly, add trace alkali in rare earth salt solution to control pH in 7-8, then add organic dispersant and stir to form evenly suspended R(OH).sub.3 particle colloid (R refers to rare earth element). Secondly pour the tungstate solution into the R(OH).sub.3colloid, add trace acid to control pH in 6-7, then add organic dispersant and stir to form tungstic acid micro particles, which wrap around the colloidal particles, forming coprecipitation coating particle colloid. Thirdly, the coprecipitation coating particle colloidal is spray-dried, forming tungsten and rare earth oxide compound precursor powder. Alter that, ultrafine or nanoscale tungsten powder with particle size of 50˜500 nm is obtained through a process of calcination subsequent with hydrogen thermal reduction. Finally, the tungsten powder is subjected to ordinary compression molding and then conventional high temperature sintering. The trace rare earth oxide dispersion strengthened high performance fine grain tungsten materials prepared by this invention, its density is close to full density (98.5% or higher), its grain size is uniform and very fine (average in 5˜10 microns), and the rare earth oxides particles evenly distribute in tungsten intracrystalline or grain, boundary with particle size of 100˜500 nm.

Provided is a simple, fast, scalable, and environmentally benign method of producing a graphene-reinforced inorganic matrix composite directly from a graphitic material, the method comprising: (a) mixing multiple particles of a graphitic material and multiple particles of an inorganic solid carrier material to form a mixture in an impacting chamber of an energy impacting apparatus; (b) operating the energy impacting apparatus with a frequency and an intensity for a length of time sufficient for peeling off graphene sheets from the graphitic material and transferring the graphene sheets to surfaces of solid inorganic carrier material particles to produce graphene coated or graphene-embedded inorganic particles inside the impacting chamber; and (c) forming graphene-coated or graphene-embedded inorganic particles into the graphene-reinforced inorganic matrix composite. Also provided is a mass of the graphene-coated or graphene-embedded inorganic particles produced by this method.

Provided is a simple, fast, scalable, and environmentally benign method of producing a graphene-reinforced inorganic matrix composite directly from a graphitic material, the method comprising: (a) mixing multiple particles of a graphitic material and multiple particles of an inorganic solid carrier material to form a mixture in an impacting chamber of an energy impacting apparatus; (b) operating the energy impacting apparatus with a frequency and an intensity for a length of time sufficient for peeling off graphene sheets from the graphitic material and transferring the graphene sheets to surfaces of solid inorganic carrier material particles to produce graphene coated or graphene-embedded inorganic particles inside the impacting chamber; and (c) forming graphene-coated or graphene-embedded inorganic particles into the graphene-reinforced inorganic matrix composite. Also provided is a mass of the graphene-coated or graphene-embedded inorganic particles produced by this method.

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.

To provide a powder material for additive layer manufacturing capable of molding a three-dimensional shaped molded article having less cracking or chipping and having high hardness and a method for manufacturing a molded article using the powder material. A powder material for additive layer manufacturing used to manufacture a three-dimensional shaped molded article by irradiation with a laser light or an electron beam contains cobalt, a first component containing one or more substances selected from the group consisting of vanadium carbide, niobium carbide, and molybdenum carbide, an optional additive component, and the balance of tungsten carbide. The content of the first component is 0.6% by mass or more and 5% by mass or less.

A metal powder for powder metallurgy contains Fe as a principal component, Cr in a proportion of 11.0 mass % or more and 25.0 mass % or less, Ni in a proportion of 8.0 mass % or more and 30.0 mass % or less, Si in a proportion of 0.20 mass % or more and 1.2 mass % or less, C in a proportion of 0.070 mass % or more and 0.40 mass % or less, Mn in a proportion of 0.10 mass % or more and 2.0 mass % or less, P in a proportion of 0.10 mass % or more and 0.50 mass % or less, and at least one of W and Nb in a proportion of 0.20 mass % or more and 3.0 mass % or less in total.

A metal powder for powder metallurgy contains Fe as a principal component, Cr in a proportion of 11.0 mass % or more and 25.0 mass % or less, Ni in a proportion of 8.0 mass % or more and 30.0 mass % or less, Si in a proportion of 0.20 mass % or more and 1.2 mass % or less, C in a proportion of 0.070 mass % or more and 0.40 mass % or less, Mn in a proportion of 0.10 mass % or more and 2.0 mass % or less, P in a proportion of 0.10 mass % or more and 0.50 mass % or less, and at least one of W and Nb in a proportion of 0.20 mass % or more and 3.0 mass % or less in total.