A method for producing a permanent magnet, comprising the step: (a) providing a powder of a magnetic material, (b) coating the powder particles with a coating of a diamagnetic or paramagnetic coating material, (c) compressing the coated particles to form a pressed part, (d) heat treatment to sinter the coating material at a temperature less than a temperature suitable for sintering the magnetic material, while the coating material transfers to a matrix of a diamagnetic or paramagnetic material, which embeds the particles of the magnetic material, and (e) magnetizing the magnetizable material in an external magnetic field, wherein the steps (c), (d) and (e) are carried out in any order successively or at the same time in any desired combination. The nanostructured permanent magnet that can be produced by mean of said method comprises cores of a permanently magnetic material having a mean particle diameter of no more than 1 m and a matrix of a diamagnetic or paramagnetic material in which the cores are embedded.

An NdFeB magnet includes a magnet body and a composite coating of metal disposed on the body. The compositing coating has a plurality of plating layers disposed on the magnet body to cover and protect the magnet body and improve corrosion resistance of the magnet body. The plating layers include a first, a second, a third, and a fourth plating layers to cover the magnet body. The first plating layer contains Zn. The second plating layer contains a Zinc-Nickel alloy. The third plating layer contains Copper. The fourth plating layer contains Nickel. A method of depositing on a composite layer on an NdFeB magnet body.

A rare earth magnet molding (1) of the present invention includes rare earth magnet particles (2), and an insulating phase (3) present among the rare earth magnet particles. Segregation regions (4) in which at least one element selected from the group consisting of Dy, Tb, Pr and Ho is segregated are distributed in the rare earth magnet particles (2). Accordingly, the rare earth magnet molding that has excellent resistance to heat in motor environments or the like while maintaining high magnetic characteristics (coercive force) is provided.

A magnet preparation method includes coating powder slurry on at least one of a first surface or a second surface of an NdFEB matrix and carrying out a curing reaction, to obtain a coated magnet, and subjecting the coated magnet to a vacuum heat treatment, a grain boundary diffusion treatment, and an aging treatment. The first surface and the second surface are opposite to each other. The powder slurry includes powder containing heavy rare earth element and UV monomer. The UV monomer includes radical-cured UV monomer. A temperature of the vacuum heat treatment is in a range from 250? C. to 600? C.

An expandable sintered neodymium-iron-boron magnet, a preparation method, and an application are provided. The magnet has a sintered neodymium-iron-boron magnet and an expandable coating coated on the surface of the sintered neodymium-iron-boron magnet. The sintered neodymium-iron-boron magnet coated with the expandable coating is used to replace a conventional assembly method of an epoxy resin adhesive coating magnet and potting resin glue, so that the magnet coated with the expandable coating may be inserted into a magnetic steel groove. The irreversible expansion of the coating itself is used to fix the magnet in the magnetic steel groove. Meanwhile, the use of the expandable coating shortens the assembly time of motors and improves the assembly accuracy of the motors.

A method for producing magnet-polymer pellets useful as a feedstock in an additive manufacturing process, comprising: (i) blending thermoplastic polymer and hard magnetic particles; (ii) feeding the blended magnet-polymer mixture into a pre-feed hopper that feeds directly into an inlet of a temperature-controlled barrel extruder; (iii) feeding the blended magnet-polymer mixture into the barrel extruder at a fixed feed rate of 5-20 kg/hour, wherein the temperature at the outlet is at least to no more than 10 C. above a glass transition temperature of the blended magnet-polymer mixture; (iv) feeding the blended magnet-polymer mixture directly into an extruding die; (v) passing the blended magnet-polymer mixture through the extruding die at a fixed speed; and (vi) cutting the magnet-polymer mixture at regular intervals as the mixture exits the extruding die at the fixed speed. The use of the pellets as feed material in an additive manufacturing process is also described.

A rare-earth element including a magnet body containing a rare-earth element, and a protective layer formed on a surface of the magnet body. The protective layer may include a first layer covering the magnet body and containing a rare-earth element, and a second layer covering the first layer and containing substantially no rare-earth element. Another protective layer in accordance may include an inner protective layer and an outer protective layer successively from the magnet body side. The outer protective layer is any of an oxide layer, a resin layer, a metal salt layer, and a layer containing an organic-inorganic hybrid compound.

A method for preparing an RFeB based sintered magnet. The method includes: 1) preparing a R.sup.1FeB-M alloy, pulverizing the R.sup.1FeB-M alloy to yield a R.sup.1FeB-M alloy powder, adding a heavy rare earth powder of R.sup.2 or R.sup.2X and subsequently adding a lubricant to the R.sup.1FeB-M alloy powder and uniformly stirring to form a mixture, where R.sup.1 being Nd, Pr, Tb, Dy, La, Gd, Ho, or a mixture thereof; M being Ti, V, Cr, Mn, Co, Ga, Cu, Si, Al, Zr, Nb, W, Mo, or a mixture thereof; R.sup.2 being at least one from Tb, Dy, and Ho; X being at least one from O, F, and Cl; 2) pressing the mixture obtained in step 1) to form a compact, and sintering the compact in a pressure sintering device in vacuum or in an inactive gas atmosphere to obtain a magnet; and 3) aging the magnet obtained in step 2).

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.

The anisotropic rare earth magnet powder of the present invention includes powder particles having R.sub.2TM.sub.14B.sub.1-type crystals of a tetragonal compound of a rare earth element (R), boron (B), and a transition element (TM) having an average crystal grain diameter of 0.05 to 1 m, and enveloping layers containing at least a rare earth element (R) and copper (Cu) and enveloping surfaces of the crystals. Owing to the presence of the enveloping layers, coercivity of the anisotropic rare earth magnet powder can be remarkably enhanced without using a scarce element such as Ga and Dy.