A sintered magnet and method of manufacturing the same are disclosed herein. According to an exemplary embodiment, a manufacturing method of a sintered magnet includes mixing the neodymium iron boron (NdFeB)-based powders and rare-earth hydride powders to prepare a mixture, heat-treating the mixture at a temperature of 600 to 850 C., and sintering the heat-treated mixture at a temperature of 1000 to 1100 C. to prepare the sintered magnet, wherein the rare earth hydride powders are neodymium hydride (NdH.sub.2) powders or mixed powers of NdH.sub.2 and praseodymium hydride (PrH.sub.2). In an embodiment, the NdFeB-based powders are prepared by a reduction-diffusion method.

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 m from a surface of the sintered magnet body.

Anisotropic rare earth magnet powder particles include R.sub.2TM.sub.14B.sub.1-type crystals of a tetragonal compound consisting of one or more rare earth element, B, and one or more transition element, and enveloping layers containing at least Nd and Cu. Surfaces of the R.sub.2TM.sub.14B.sub.1-type crystals are enveloped by the enveloping layers. The particles has an average crystal grain diameter of 0.05 to 1 m. The particles contain, when the whole particles are taken as 100 atomic %, 11.5 to 15 atomic % of total rare earth element (Rt); 5.5 to 8 atomic % of B; and about 0.05 atomic % to about 2 atomic % of Cu. The powder particles have an atomic ratio of Cu, which is a ratio of the total number of Cu atoms to a total number of atoms of Rt, falling within the range of 1 to 6%. The powder particles do not include dysprosium Dy, Tb, Ho and Ga. Coercivity of the magnetic powder is more than 955 kA/m.

A method of stabilizing soft particles to create dried nanocomposite magnets includes coating a plurality of soft particles with a layer of SiO.sub.2, the soft particles being nanoparticles, creating a composite by mixing the soft particles with hard phase via a solution phase based assembly, annealing the composite, washing the composite with an alkaline solution to remove SiO.sub.2, and compacting the composite to create dried nanocomposite magnets.

To provide a rare earth magnet ensuring excellent magnetic anisotropy while reducing the amount of Nd, etc., and a manufacturing method thereof.

A rare earth magnet comprising a crystal grain having an overall composition of (R2.sub.(1-x)R1.sub.x).sub.yFe.sub.100-y-w-z-vCo.sub.wB.sub.zTM.sub.v (wherein R2 is at least one of Nd, Pr, Dy and Tb, R1 is an alloy of at least one or two or more of Ce, La, Gd, Y and Sc, TM is at least one of Ga, Al, Cu, Au, Ag, Zn, In and Mn, 0<x<1, y=12 to 20, z=5.6 to 6.5, w=0 to 8, and v=0 to 2), wherein the average grain size of the crystal grain is 1,000 nm or less, the crystal grain consists of a core and an outer shell, the core has a composition of R1 that is richer than R2, and the outer shell has a composition of R2 that is richer than R1.

The present invention relates to a method for preparing a neodymium-iron-boron rare-earth permanent magnetic material, in particular to a hot press molding-based method for preparing a rare-earth permanent magnet. The problem that the residual magnetism and coercive force of a rare-earth permanent magnet prepared in the prior art cannot be both high is solved. An RTM alloy infiltrates same during an HD treatment. RTM sticks to the surface of coarse powder and infiltrates into the interior of the coarse powder along a grain boundary. The temperature of hot press sintering is relatively low, and grains barely grow. In the absence of Dy and Tb, a higher coercive force is obtained. If an alloy containing Dy and Tb is used for infiltration, these atoms diffuse into the surface layer of a main phase during preheating and heat treatment, achieving grain boundary hardening. Under the premise of a very small reduction in the residual magnetism, the coercive force is greatly improved.

To provide a rare earth magnet ensuring excellent magnetic anisotropy while reducing the amount of Nd, etc., and a manufacturing method thereof. A rare earth magnet comprising a crystal grain having an overall composition of (R2.sub.(1-x)R1.sub.x).sub.yFe.sub.100-y-w-z-vCo.sub.wB.sub.zTM.sub.v (wherein R2 is at least one of Nd, Pr, Dy and Tb, R1 is an alloy of at least one or two or more of Ce, La, Gd, Y and Sc, TM is at least one of Ga, Al, Cu, Au, Ag, Zn, In and Mn, 0<x<1, y=12 to 20, z=5.6 to 6.5, w=0 to 8, and v=0 to 2), wherein the average grain size of the crystal grain is 1,000 nm or less, the crystal grain consists of a core and an outer shell, the core has a composition of R1 that is richer than R2, and the outer shell has a composition of R2 that is richer than R1.

A method for preparing a metal powder includes preparing a mixture by mixing a fluoride of a group 1 element, a fluoride of a group 2 element or a transition metal fluoride, with neodymium oxide, boron, iron, and a reducing agent; and heating the mixture at a temperature of 800 C. to 1100 C.

Articles, devices and machines are disclosed for initiating structural changes based on material magnetic properties to cause self-adjustment to improve the operation or function of structures, devices or machines. In one aspect, a device exhibiting a self-healing property to repair a damage, the device including a device structure over which magnetic microparticles are dispersed to impart a self-healing ability to enable the device structure, once damaged to have a broken portion, to self-repair based on magnetic attraction of the dispersed magnetic microparticles to cause re-attachment of the broken portion.

A hybrid rare-earth-iron-boron hard magnetic material is constituted of two materials, a first magnetic alloy of chemical composition Nd120.2Fe820.2B60.2 in atomic percent with each single particle surrounded and chemically bonded to a second material constituted by copper, zinc, or a mixture of the foregoing such as brass alloys. The mixture of the first and second materials is magnetically oriented, compacted and densified such as through sintering, to optimize its mechanical and magnetic properties.