The present disclosure is directed at methods of preparing rare earth-based permanent magnets having improved coercivity and remanence, the method comprising one or more steps comprising: (a) homogenizing a first population of particles of a first GBM alloy with a second population of particles of a second core alloy to form a composite alloy preform, the first GBM alloy being substantially represented by the formula: AC.sub.bR.sub.xCo.sub.yCu.sub.dM.sub.z, the second core alloy being substantially represented by the formula G.sub.2Fe.sub.14B, where AC, R, M, G, b, x, y, and z are defined; (b) heating the composite alloy preform particles to form a population of mixed alloy particles; (c) compressing the mixed alloy particles, under a magnetic field of a suitable strength to align the magnetic particles with a common direction of magnetization and inert atmosphere, to form a green body; (d) sintering the green body; and (e) annealing the sintered body. Particular embodiments include magnets comprising neodymium-iron-boron core alloys, including Nd.sub.2Fe.sub.14B.

The present disclosure is directed at methods of preparing rare earth-based permanent magnets having improved coercivity and remanence, the method comprising one or more steps comprising: (a) homogenizing a first population of particles of a first GBM alloy with a second population of particles of a second core alloy to form a composite alloy preform, the first GBM alloy being substantially represented by the formula: AC.sub.bR.sub.xCo.sub.yCu.sub.dM.sub.z, the second core alloy being substantially represented by the formula G.sub.2Fe.sub.14B, where AC, R, M, G, b, x, y, and z are defined; (b) heating the composite alloy preform particles to form a population of mixed alloy particles; (c) compressing the mixed alloy particles, under a magnetic field of a suitable strength to align the magnetic particles with a common direction of magnetization and inert atmosphere, to form a green body; (d) sintering the green body; and (e) annealing the sintered body. Particular embodiments include magnets comprising neodymium-iron-boron core alloys, including Nd.sub.2Fe.sub.14B.

A silver particle synthesizing method includes reducing a dispersant from first silver particles each covered with the dispersant to obtain second silver particles. The method further includes synthesizing third silver particles each having a larger particle diameter than the second silver particles by causing a reaction between a silver compound and a reductant in a liquid phase containing the second silver particles.

A silver particle synthesizing method includes reducing a dispersant from first silver particles each covered with the dispersant to obtain second silver particles. The method further includes synthesizing third silver particles each having a larger particle diameter than the second silver particles by causing a reaction between a silver compound and a reductant in a liquid phase containing the second silver particles.

There is provided a sintered bearing having high rotational accuracy and low rotational fluctuation. This bearing includes a bearing surface (4a), and is made of a sintered compact (4) produced by molding and sintering a raw material powder (10) containing a partially diffusion-alloyed powder (11) in which a copper powder (13) is partially diffused on a surface of an iron powder (12), a tin powder (14) as a low-melting-point metal powder, and a graphite powder as a solid lubricant powder. The sintered bearing has a radial crushing strength greater than or equal to 300 MPa.

There is provided a sintered bearing having high rotational accuracy and low rotational fluctuation. This bearing includes a bearing surface (4a), and is made of a sintered compact (4) produced by molding and sintering a raw material powder (10) containing a partially diffusion-alloyed powder (11) in which a copper powder (13) is partially diffused on a surface of an iron powder (12), a tin powder (14) as a low-melting-point metal powder, and a graphite powder as a solid lubricant powder. The sintered bearing has a radial crushing strength greater than or equal to 300 MPa.

A magnetic material includes a soft magnetic metal grain containing Fe, and a multilayer oxide film covering the surfaces of the soft magnetic metal grain. The multilayer oxide film has a first oxide layer of crystalline nature containing Fe, and a second oxide layer of amorphous nature containing Si. In an embodiment, the silicon oxide film of amorphous nature is formed by dripping, divided into multiple sessions, a treatment solution containing TEOS (tetraethoxy silane), ethanol, and water into a mixed solution containing the soft magnetic metal grain, ethanol, and ammonia water, to mix the solutions.

A magnetic material includes a soft magnetic metal grain containing Fe, and a multilayer oxide film covering the surfaces of the soft magnetic metal grain. The multilayer oxide film has a first oxide layer of crystalline nature containing Fe, and a second oxide layer of amorphous nature containing Si. In an embodiment, the silicon oxide film of amorphous nature is formed by dripping, divided into multiple sessions, a treatment solution containing TEOS (tetraethoxy silane), ethanol, and water into a mixed solution containing the soft magnetic metal grain, ethanol, and ammonia water, to mix the solutions.

A composite powder comprising powder particles is disclosed. Each powder particle comprises a core element and a diffusion layer at least partially surrounding the core element. The core element comprises copper, gold or silver and an alloy element capable of forming a nitride, a carbide or a carbonitride. The diffusion layer comprises the alloy element and a nitride, carbide or carbonitride compound. The nitride, carbide or carbonitride compound comprises the alloy element.

A composite powder comprising powder particles is disclosed. Each powder particle comprises a core element and a diffusion layer at least partially surrounding the core element. The core element comprises copper, gold or silver and an alloy element capable of forming a nitride, a carbide or a carbonitride. The diffusion layer comprises the alloy element and a nitride, carbide or carbonitride compound. The nitride, carbide or carbonitride compound comprises the alloy element.