A NdFeB permanent magnet is provided and includes Nd of about 25 to 30 wt %, Dy of about 0.5 to 6 wt %, Tb of about 0.2 to 2 wt %, Cu of about 0.1 to 0.5 wt %, B of about 0.8 to 2 wt %, a balance of Fe and other inevitable impurities. In addition, a method for producing the permanent magnet is provided.

Disclosed is a method of manufacturing a rare earth permanent magnet with substantially improved magnetic property. The method comprises: preparing a magnet master alloy by melting an R-T-B based alloy; pulverizing the magnet master alloy to provide a magnet powder; pressurizing the magnet powder as applying magnetic field to the magnet powder under an inert atmosphere to form a magnet molded body; sintering the magnet molded body under a vacuum atmosphere to obtain a sintered magnet molded body having oxygen content of about 0.1 wt % or less based on the total weight of the sintered magnet molded body; and treating the sintered magnet molded body with Dy and Tb.

In at least one embodiment, a single sintered magnet is provided having a concentration profile of heavy rare-earth (HRE) elements within a continuously sintered rare-earth (RE) magnet bulk. The concentration profile may include at least one local maximum of HRE element concentration within the bulk such that a coercivity profile of the magnet has at least one local maximum within the bulk. The magnet may be formed by introducing alternating layers of an HRE containing material and a magnetic powder into a mold, pressing the layers into a green compact, and sintering the green compact to form a single, unitary magnet.

A sintered annular magnet with a radial orientation of a remanent magnetic field, including: a principal annular part made from a ferromagnetic material, that has a first degree of magnetic anisotropy in the radial direction; and an annular reinforcing part fixed to the principal part of the magnet, the reinforcing part being made from same ferromagnetic material as the ferromagnetic material forming the principal part, and that has a second degree of magnetic anisotropy in the radial direction, the first degree being higher than the second degree.

Magnet arrangements, sensor devices and corresponding methods are provided comprising a first magnet portion and a second magnet portion. The first magnet portion is spaced apart from the second magnet portion, and the second magnet portion comprises a bore. In a corresponding sensor device, a sensor element may be provided at a position between the first and second magnet portions.

An R-T-B permanent magnet comprises rare-earth elements R, transition metal elements T, and boron B; wherein at least some of the rare-earth elements R is Nd and at least one of Tb and Dy; at least some of the transition metal elements T are Fe; the R-T-B permanent magnet comprises a plurality of main phase grains and grain boundary triple points each surrounded by the main phase grains; the grain boundary triple points comprise at least one of Nd and Pr, at least one of Tb and Dy, at least one of Fe and Co, and copper; the average contents of Nd, Pr, Tb, Dy, Fe, Co and Cu each (unit: atom %) are represented by [Nd], [Pr], [Tb], [Dy], [Fe], [Co] and [Cu]; ([Fe]+[Co])/([Nd]+[Pr]) is 2 or more and 5 or less; and [Cu]/([Tb]+[Dy]) is 1 or more and 4 or less.

The present invention provides an R-T-B based permanent magnet having excellent magnetic properties and corrosion resistance even when Co content is small. The R-T-B based permanent magnet in which R is a rare earth element including one or more selected from Nd and Pr and one or more selected from Dy and Tb, T is a combination of Fe and Co, and B is boron. The R-T-B based permanent magnet further includes Zr. A total content of Nd, Pr, Dy, and Tb is 30.00 mass % to 32.20 mass %, Co content is 0.30 mass % to 1.30 mass %, Zr content is 0.21 mass % to 0.85 mass %, and B content is 0.90 mass % to 1.02 mass % with respect to 100 mass % of the R-T-B based permanent magnet.

The present invention discloses a rare earth permanent magnet and a method for preparing same. The material of the rare earth permanent magnet has a heavy rare earth element volume diffusion phenomenon at a depth of 5 μm to 100 μm from the surface of the magnet to the interior of the magnet along the magnetic field orientation direction, thereby forming a volume diffusion layer region; the volume diffusion layer region is divided into magnet units having a volume of 10*100*5 μm, and the concentration difference of the heavy rare earth elements of the magnet units at different positions in the volume diffusion layer is below 0.5 at %. The present invention provides a sintered NdFeB magnet of high intrinsic coercive force Hcj on the premise of not influencing the remanence Br and the maximum magnetic energy product (BH)max of products. In the method for preparing the rare earth permanent magnet, microwave heat treatment is performed on a blank magnet coated with heavy rare earth source slurry in a vacuum condition. This method can effectively improve the heating efficiency, reduce the heat treatment time, lower the energy consumption, and reduce the production cost of the magnet.

A method of producing a sintered magnet is disclosed herein. In some embodiments, a method of producing a sintered magnet comprises, sintering a R—Fe—B based magnetic powder to produce a sintered magnet; wherein the R is Nd, Pr, Dy, Ce or Tb, and infiltrating a eutectic alloy into the sintered magnet, wherein the eutectic alloy contains Pr, Al, Cu and Ga, and wherein infiltration the eutectic alloy includes applying the eutectic alloy to the sintered magnet and heat-treating the sintered magnet to which the eutectic alloy is applied.

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.