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- Nachgewiesen in: USPTO Patent Applications
- Sprachen: English
- Document Number: 20240055163
- Publication Date: February 15, 2024
- Appl. No: 18/448487
- Application Filed: August 11, 2023
- Claim: 1. An R—Fe—B permanent magnet, wherein the permanent magnet comprises at least a grain boundary and composite main phase grains; the grain boundary comprises an RH-rich phase distributed in the form of an agglomerate within the grain boundary between the composite main phase grains, preferably at the intersection of any adjacent three or more composite main phase grains; the RH-rich phase is continuously distributed along the grain boundary in the form of a thin-layer stripe; RH in the grain boundary has a content greater than that of the RH in the main phase grains, and the RH is at least one selected from heavy rare earth metals such as Dy, Tb, and Ho; the composite main phase grain has a core-shell structure, wherein the core-shell structure comprises a core structure having an R-T-B type phase structure and a shell structure on the outer layer of the core structure; the core structure comprises Ce-rich main phase grains and Ce-poor main phase grains; wherein Ce in the Ce-rich main phase grains has a content of 1-15 wt %, and Ce in the Ce-poor main phase grains has a content of 0-1 wt %.
- Claim: 2. The R—Fe—B permanent magnet according to claim 1, wherein the RH in the grain boundary has a content greater than that of the RH in the shell structure; preferably, the permanent magnet comprises RL, the RL is at least one selected from light rare earth metals such as Pr and Nd; and preferably, RL in the shell structure has a content greater than or equal to that of the RL in the core structure.
- Claim: 3. The R—Fe—B permanent magnet according to claim 1, wherein the R-T-B type phase structure comprises at least the following components: R, with a weight percentage of 28%≤R≤35%, wherein the R is selected from neodymium (Nd) and cerium (Ce), and optionally comprises or does not comprise at least one selected from scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu); B, with a weight percentage of 0.8%≤B≤1.2%; M, with a weight percentage of 0≤M≤5%, wherein the M is at least one selected from aluminum (Al), titanium (Ti), copper (Cu), gallium (Ga), zirconium (Zr), and niobium (Nb); and the balance of T, wherein the T consists of iron (Fe) and optionally presented cobalt (Co).
- Claim: 4. The R—Fe—B permanent magnet according to claim 1, wherein the permanent magnet is prepared by mixing a powder of a low-Ce master alloy and a powder of a high-Ce auxiliary alloy, press molding, sintering treatment, and then performing composite diffusion treatment; preferably, Ce in the low-Ce master alloy has a content not greater than 1 wt %, preferably 0-1 wt %; preferably, Ce in the high-Ce auxiliary alloy has a content greater than 1 wt % and not greater than 15 wt %; and preferably, the permanent magnet, from the surface to the core, has phase structures of the grain boundary and the composite main phase grains.
- Claim: 5. A preparation method of the permanent magnet according to claim 1, wherein the preparation method comprises mixing a powder of a low-Ce master alloy and a powder of a high-Ce auxiliary alloy, press molding, and sintering treatment to obtain a blank, and performing composite diffusion treatment on the blank to obtain the permanent magnet.
- Claim: 6. The preparation method according to claim 5, wherein Ce in the low-Ce master alloy has a content not greater than 1 wt %, preferably 0-1 wt %; preferably, Ce in the high-Ce auxiliary alloy has a content greater than 1 wt % and not greater than 15 wt %; and preferably, the powder of the low-Ce master alloy and the powder of the high-Ce auxiliary alloy are in a mass ratio of (1-50):1.
- Claim: 7. The preparation method according to claim 5, wherein the press molding comprises mixing the powder of the low-Ce master alloy and the powder of the high-Ce auxiliary alloy, and then press molding under the action of a magnetic field to obtain a green body; preferably, after press molding, cold isostatic pressing treatment can also be performed to further improve the density of the blank; and preferably, the sintering treatment comprises heating the green body to 1000-1100° C. under a vacuum atmosphere to obtain a blank.
- Claim: 8. The preparation method according to claim 5, wherein the composite diffusion treatment comprises: arranging a diffusion material on the surface of the blank, and performing heat treatment; preferably, the surface of the blank is uniformly coated with a slurry containing the diffusion material; preferably, the diffusion material comprises RH and RL optionally with or without the addition of an M powder; preferably, the RH is at least one selected from heavy rare earth metals such as Dy, Tb, and Ho; preferably, the RL is at least one selected from light rare earth metals such as Pr and Nd; and preferably, the M powder is selected from Ga and/or Cu.
- Claim: 9. The preparation method according to claim 8, wherein the diffusion material comprises the following components: RH with a content of 20-70 wt %, RL with a content of 20-70 wt %, and an M powder with a content of 0-10 wt %; preferably, the RH, the RL, and the M powder in the diffusion material are in a mass ratio of (1-10):(1-5):(0-2); preferably, the RH and the RL are provided by powders of the RH and the RL, respectively; preferably, the powder of the RH is at least one selected from a single metal of the RH, an alloy of the RH, an oxide of the RH, a fluoride of the RH, a hydride of the RH, and an oxyfluoride of the RH; and preferably, the powder of the RL is at least one selected from a single metal of the RL, an alloy of the RL, an oxide of the RL, a fluoride of the RL, a hydride of the RL, and an oxyfluoride of the RL.
- Claim: 10. Use of the permanent magnet according to claim 1, wherein the permanent magnet is used for a motor.
- Current International Class: 01
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