Low-boron R-Fe-B permanent magnet material and preparation method thereof

Abstract

The invention provides a low-boron R-Fe-B permanent magnet material and a preparation method thereof, and belongs to the technical field of rare earth permanent magnet materials. An R-Fe-B-M alloy and a grain boundary phase R-Ga-M alloy are sequentially crushed and dehydrogenated to obtain a coarse material, the coarse material is mixed with an antioxidant, a lubricating agent and a dispersing agent, and then compression molding, cold isostatic pressing treatment, vacuum degassing, vacuum low-temperature sintering and aging treatment are carried out. In the R-Fe-B-M alloy, the content of R is 29 wt%-36 wt%, the content of B is 0.8 wt%-0.96 wt%, the R-Fe-B-M alloy belongs to an alloy with excessive rare earth elements and low content of B, more rare earth-rich grain boundary phases can be generated, the R-Ga-M alloy is low in melting point and beneficial to liquid phase sintering, and by combining a three-section type heating delay sintering process of firstly performing vacuum degassing and applying pressure-assisted diffusion air pressure, the high-temperature-resistant performance of the R-Fe-B-M alloy can be improved, so that the high-temperature-resistant performance of the R-Fe-B-M alloy is improved, and the yield of the R-Fe-B-M alloy is improved. And the low-boron R-Fe-B permanent magnet material can be obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of rare earth permanent magnet materials, and in particular to a low-boron R-Fe-B permanent magnet material and a preparation method thereof. Background Art

[0002] The Nd-Fe-B rare earth permanent magnet material is the third-generation rare earth permanent magnet material, which has excellent comprehensive magnetic properties and belongs to the core functional materials. The rapid development of new energy vehicles, industrial servo motors, wind power generation, rail transit and other fields has stimulated the increasing demand for high-performance sintered neodymium iron boron magnets in the market.

[0003] In the related processes, the technical route for preparing Nd-Fe-B sintered magnets adopts the grain boundary diffusion process that can greatly improve the utilization efficiency of heavy rare earth resources, that is, the grain boundary diffusion treatment of the diffusion substrate is carried out by means of surface impregnation, electrophoretic deposition, evaporation coating, magnetron sputtering method, etc. with a diffusion source containing heavy rare earth elements. After the grain boundary diffusion process, high-temperature sintering treatment and heat treatment are carried out to obtain the permanent magnet material, and there is a problem of high high-temperature sintering treatment temperature, and the temperature is 1060~1085°C. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a low-boron R-Fe-B permanent magnet material and a preparation method thereof. The low-boron R-Fe-B permanent magnet material can be obtained by vacuum low-temperature sintering in the present invention.

[0005] In order to achieve the above-mentioned invention purpose, the present invention provides the following technical solutions: The present invention provides a preparation method of a low-boron R-Fe-B permanent magnet material, comprising the following steps: The R-Fe-B-M alloy is subjected to first crushing and first dehydrogenation in sequence to obtain a R-Fe-B-M alloy rough material; in the R-Fe-B-M alloy, R is a rare earth element, including one or more of Nd, Pr, La, Ce, Y and Sm, M includes one or more of Cu, Al, Co, Ga, Ni, Ti, Nb, Zr, Ge, Zn, Sn, Ag, V, Cr, Mn, W, Mo and Si, and the content of R in the R-Fe-B-M alloy is 29wt%~36wt%, and the content of B element is 0.8wt%~0.96wt%; The grain boundary phase R-Ga-M alloy is subjected to secondary crushing and secondary dehydrogenation in sequence to obtain a coarse grain boundary phase R-Ga-M alloy; in the grain boundary phase R-Ga-M alloy, R is a rare earth element, including one or more of Nd, Pr, La, Ce, and Sm, M includes one or more of Dy, Tb, Gd, Y, and Ho, the content of R in the grain boundary phase R-Ga-M alloy is 60 wt% - 90 wt%, the content of Ga element is 10 wt% - 20 wt%, and the content of M element is 0 wt% - 30 wt% and not 0 wt%; Mix the R-Fe-B-M alloy coarse material, the grain boundary phase R-Ga-M alloy coarse material, an antioxidant, a lubricant, and a dispersant, and then perform molding under a magnetic field to obtain a blank; Perform cold isostatic pressing on the blank to obtain a green compact; Perform vacuum degassing, vacuum low-temperature sintering, and aging treatment on the green compact in sequence to obtain the low-boron series R-Fe-B permanent magnet material. The pressure of the vacuum low-temperature sintering is 0.05 - 1 MPa. The vacuum low-temperature sintering includes first vacuum low-temperature sintering, second vacuum low-temperature sintering, and third vacuum low-temperature sintering in sequence. The temperature of the first vacuum low-temperature sintering is 470 - 580 °C, the holding time of the first vacuum low-temperature sintering is 4 - 12 h, the temperature of the second vacuum low-temperature sintering is 650 - 730 °C, the holding time of the second vacuum low-temperature sintering is 4 - 12 h, the temperature of the third vacuum low-temperature sintering is 900 - 1000 °C, and the holding time of the third vacuum low-temperature sintering is 4 - 30 h.

[0006] Preferably, when mixing, the mass W1 of the R-Fe-B-M alloy coarse material and the mass W2 of the grain boundary phase R-Ga-M alloy coarse material satisfy the relationship: W2 = (0.1% - 2%) × W1.

[0007] Preferably, the content of M element in the R-Fe-B-M alloy is 1 wt% - 2 wt%, and the balance is Fe element and inevitable impurities; when M in the R-Fe-B-M alloy includes one or more of Ga, Ge, Zn, Sn, Ag, and Si, the contents of Ga, Ge, Zn, Sn, Ag, and Si in the R-Fe-B-M alloy are independently 0 wt% - 0.20 wt% and not 0 wt%.

[0008] Preferably, the temperature of the first dehydrogenation is 320 - 580 °C.

[0009] Preferably, the temperature of the second dehydrogenation is 400 - 500 °C.

[0010] Preferably, the vacuum degree of the vacuum degassing is lower than 9×10 -3Pa. The vacuum degassing includes first vacuum degassing, second vacuum degassing, and third vacuum degassing carried out in sequence. The temperature of the first vacuum degassing is 330 - 360 °C, the heat preservation time of the first vacuum degassing is 1 - 4 h, the temperature of the second vacuum degassing is 550 - 580 °C, the heat preservation time of the second vacuum degassing is 1 - 4 h, the temperature of the third vacuum degassing is 850 - 880 °C, and the heat preservation time of the third vacuum degassing is 1 - 4 h.

[0011] Preferably, the vacuum degree of the aging treatment is lower than 9×10 -3 Pa. The aging treatment includes first aging treatment and second aging treatment carried out in sequence. The temperature of the first aging treatment is 880 - 910 °C, the heat preservation time of the first aging treatment is 2 - 4 h, the temperature of the second aging treatment is 440 - 520 °C, and the heat preservation time of the second aging treatment is 2 - 4 h.

[0012] Preferably, the pressure of the cold isostatic pressing treatment is 180 - 220 MPa.

[0013] Preferably, the intensity of the magnetic field is 1.5 - 2.5 T.

[0014] The present invention also provides a low-boron series R-Fe-B permanent magnetic material prepared by the preparation method described in the above technical solution.

[0015] The present invention provides a preparation method of a low-boron R-Fe-B permanent magnet material, comprising the following steps: successively performing first crushing and first dehydrogenation on an R-Fe-B-M alloy to obtain a coarse R-Fe-B-M alloy material; in the R-Fe-B-M alloy, R is a rare earth element, including one or more of Nd, Pr, La, Ce, Y and Sm, M includes one or more of Cu, Al, Co, Ga, Ni, Ti, Nb, Zr, Ge, Zn, Sn, Ag, V, Cr, Mn, W, Mo and Si, the content of R in the R-Fe-B-M alloy is 29 wt% - 36 wt%, and the content of B element is 0.8 wt% - 0.96 wt%; successively performing second crushing and second dehydrogenation on a grain boundary phase R-Ga-M alloy to obtain a coarse grain boundary phase R-Ga-M alloy material; in the grain boundary phase R-Ga-M alloy, R is a rare earth element, including one or more of Nd, Pr, La, Ce and Sm, M includes one or more of Dy, Tb, Gd, Y and Ho, the content of R in the grain boundary phase R-Ga-M alloy is 60 wt% - 90 wt%, the content of Ga element is 10 wt% - 20 wt%, and the content of M element is 0 wt% - 30 wt% and not 0 wt%; mixing the coarse R-Fe-B-M alloy material, the coarse grain boundary phase R-Ga-M alloy material, an antioxidant, a lubricant and a dispersant, and then performing pressing and forming under a magnetic field to obtain a blank; performing cold isostatic pressing treatment on the blank to obtain a compact; successively performing vacuum degassing, vacuum low-temperature sintering and aging treatment on the compact to obtain the low-boron R-Fe-B permanent magnet material, the pressure of the vacuum low-temperature sintering is 0.05 - 1 MPa, the vacuum low-temperature sintering includes successively performed first vacuum low-temperature sintering, second vacuum low-temperature sintering and third vacuum low-temperature sintering, the temperature of the first vacuum low-temperature sintering is 470 - 580 °C, the heat preservation time of the first vacuum low-temperature sintering is 4 - 12 h, the temperature of the second vacuum low-temperature sintering is 650 - 730 °C, the heat preservation time of the second vacuum low-temperature sintering is 4 - 12 h, the temperature of the third vacuum low-temperature sintering is 900 - 1000 °C, and the heat preservation time of the third vacuum low-temperature sintering is 4 - 30 h.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: In the present invention, the content of R in the R-Fe-B-M alloy is 29 wt% to 36 wt%, and the content of B element is 0.8 wt% to 0.96 wt%. It belongs to an alloy with excessive rare earth elements and low B element content, which is beneficial to generate more rare earth-rich grain boundary phases. The R-Ga-M alloy is a low-melting-point alloy mainly composed of light rare earth elements and assisted by heavy rare earth elements, which is conducive to liquid-phase sintering. Combined with prior vacuum degassing and using a three-stage temperature-raising delay sintering process of pressure-assisted diffusion gas pressure, the raw materials can be melted into a liquid phase during vacuum low-temperature sintering treatment, promoting the densification of the magnet and simultaneously performing grain boundary diffusion sintering. A low-boron R-Fe-B permanent magnet material can be obtained through vacuum low-temperature sintering. Moreover, the present invention adds an R-Ga-M alloy, does not require an additional grain boundary diffusion process, and is not limited to the thickness of the magnet, which is different from the related technology that requires machining the magnet obtained through sintering and aging treatments into a specific-shaped diffusion substrate (with a thickness less than 8 mm). At the same time, the present invention reduces the usage amount of gallium element (Ga usage amount is less than 0.4 wt%), can reduce the production cost, and does not require adding special grain boundary diffusion equipment. The entire preparation process is short and easy to operate, suitable for large-scale industrial production, and further reduces the production cost.

[0017] The data of the examples show that the remanence Br of the low-boron R-Fe-B permanent magnet material prepared by the present invention is ≥14.00 kGs, and the intrinsic coercivity Hcj is ≥20 kOe.

[0018] The present invention also provides a low-boron R-Fe-B permanent magnet material prepared by the preparation method described in the above technical solution. The low-boron R-Fe-B permanent magnet material of the present invention can be applied to new energy vehicles, wind power new energy, automotive energy-saving electrical appliances, energy-saving household appliances, energy-saving elevators, intelligent equipment such as robots, and intelligent consumer electronics fields such as mobile phones. Detailed Embodiments

[0019] The present invention provides a preparation method for a low-boron R-Fe-B permanent magnet material, comprising the following steps: The R-Fe-B-M alloy is successively subjected to first crushing and first dehydrogenation to obtain a coarse R-Fe-B-M alloy; R in the R-Fe-B-M alloy is a rare earth element, including one or more of Nd, Pr, La, Ce, Y, and Sm, and M includes one or more of Cu, Al, Co, Ga, Ni, Ti, Nb, Zr, Ge, Zn, Sn, Ag, V, Cr, Mn, W, Mo, and Si. The content of R in the R-Fe-B-M alloy is 29 wt% to 36 wt%, and the content of B element is 0.8 wt% to 0.96 wt%; The grain boundary phase R-Ga-M alloy is subjected to secondary crushing and secondary dehydrogenation in sequence to obtain a coarse material of the grain boundary phase R-Ga-M alloy; in the grain boundary phase R-Ga-M alloy, R is a rare earth element, including one or more of Nd, Pr, La, Ce, and Sm, and M includes one or more of Dy, Tb, Gd, Y, and Ho. The content of R in the grain boundary phase R-Ga-M alloy is 60wt% - 90wt%, the content of Ga element is 10wt% - 20wt%, and the content of M element is 0wt% - 30wt% and not 0wt%. The coarse material of the R-Fe-B-M alloy, the coarse material of the grain boundary phase R-Ga-M alloy, an antioxidant, a lubricant, and a dispersant are mixed, and then are compacted under a magnetic field to obtain a blank. The blank is subjected to cold isostatic pressing treatment to obtain a green compact. The green compact is subjected to vacuum degassing, vacuum low-temperature sintering, and aging treatment in sequence to obtain the low-boron series R-Fe-B permanent magnetic material. The pressure of the vacuum low-temperature sintering is 0.05 - 1MPa. The vacuum low-temperature sintering includes first vacuum low-temperature sintering, second vacuum low-temperature sintering, and third vacuum low-temperature sintering carried out in sequence. The temperature of the first vacuum low-temperature sintering is 470 - 580°C, the heat preservation time of the first vacuum low-temperature sintering is 4 - 12h, the temperature of the second vacuum low-temperature sintering is 650 - 730°C, the heat preservation time of the second vacuum low-temperature sintering is 4 - 12h, the temperature of the third vacuum low-temperature sintering is 900 - 1000°C, and the heat preservation time of the third vacuum low-temperature sintering is 4 - 30h.

[0020] In the present invention, unless otherwise specified, the raw materials used are commercially available products in the art or raw materials prepared by conventional preparation methods in the art.

[0021] In the present invention, the R-Fe-B-M alloy is subjected to primary crushing and primary dehydrogenation in sequence to obtain a coarse material of the R-Fe-B-M alloy; in the R-Fe-B-M alloy, R is a rare earth element, including one or more of Nd, Pr, La, Ce, Y, and Sm, and M includes one or more of Cu, Al, Co, Ga, Ni, Ti, Nb, Zr, Ge, Zn, Sn, Ag, V, Cr, Mn, W, Mo, and Si. The content of R in the R-Fe-B-M alloy is 29wt% - 36wt%, and the content of B element is 0.8wt% - 0.96wt%.

[0022] In the present invention, the content of R in the R-Fe-B-M alloy may specifically be 29 wt%, 29.5 wt%, 30 wt%, 31 wt%, 32 wt%, 33 wt%, 34 wt%, 35 wt% or 36 wt%, and the content of B element may specifically be 0.8 wt%, 0.85 wt%, 0.9 wt%, 0.95 wt% or 0.96 wt%; the R-Fe-B-M alloy belongs to an alloy with excessive rare earth elements and low B element content, which is beneficial to generate more rare earth-rich grain boundary phases.

[0023] In the present invention, the content of M element in the R-Fe-B-M alloy is preferably 1 wt% to 2 wt%, and may specifically be 1 wt%, 1.2 wt%, 1.4 wt%, 1.55 wt%, 1.7 wt% or 2 wt%, and the balance is Fe element and inevitable impurities; when M in the R-Fe-B-M alloy preferably includes one or more of Ga, Ge, Zn, Sn, Ag and Si, the contents of Ga, Ge, Zn, Sn, Ag and Si in the R-Fe-B-M alloy are independently 0 wt% to 0.20 wt% and not 0 wt%, and may specifically be 0.05 wt%, 0.1 wt%, 0.15 wt% or 0.20 wt%; in the present invention, controlling the contents of each element in the R-Fe-B-M alloy within the above ranges can form an alloy with high rare earth content but low gallium.

[0024] In a specific embodiment of the present invention, the R-Fe-B-M alloy is preferably (Pr0.2Nd0.8)30FebalCu0.4Co0.5Ga0.15Zr0.2Ti0.3B0.9 (wt%), (Pr0.2Nd0.8)32FebalCu0.2Co0.5Ga0.1Ti0.15Nb0.25B0.85 (wt%), (Pr0.25Nd0.75)33FebalCu0.3Co0.5Ga0.15Ti0.2Nb0.25B0.85 (wt%) or (Pr0.25Nd0.75)29.5Ce1.5FebalCu0.4Co0.8Ga0.15Zr0.15Nb0.2B0.9 (wt%).

[0025] In the present invention, the R-Fe-B-M alloy is preferably used in the form of alloy cast sheets, and the thickness of the alloy cast sheets is preferably 0.1 to 0.6 mm, and may specifically be 0.1, 0.2, 0.24, 0.26, 0.3, 0.4, 0.5 or 0.6 mm. The present invention has no special limitation on the source of the alloy cast sheets, and it is preferably an alloy cast sheet prepared by a vacuum thin-sheet rapid solidification furnace. The present invention has no special limitation on the specific parameters for preparing the alloy cast sheets by the vacuum thin-sheet rapid solidification furnace.

[0026] In the present invention, the temperature of the first dehydrogenation is preferably 320-580 °C, specifically, it can be 320, 360, 400, 440, 480, 500, 520, 540, 560 or 580 °C.

[0027] In the present invention, the first crushing is preferably hydrogen crushing. The present invention has no special limitations on the parameters of the first crushing and the time of the first dehydrogenation, as long as saturated dehydrogenation can be achieved.

[0028] In the present invention, the grain boundary phase R-Ga-M alloy is successively subjected to second crushing and second dehydrogenation to obtain a coarse material of the grain boundary phase R-Ga-M alloy; in the grain boundary phase R-Ga-M alloy, R is a rare earth element, including one or more of Nd, Pr, La, Ce and Sm, and M includes one or more of Dy, Tb, Gd, Y and Ho. The content of R in the grain boundary phase R-Ga-M alloy is 60wt%-90wt%, the content of Ga element is 10wt%-20wt%, and the content of M element is 0wt%-30wt% and not 0wt%.

[0029] In the present invention, the content of R in the grain boundary phase R-Ga-M alloy is specifically 60wt%, 70wt%, 80wt% or 90wt%; the content of Ga element can specifically be 10wt%, 15wt% or 20wt%; the content of M element can specifically be 5wt%, 10wt%, 15wt%, 20wt%, 25wt% or 30wt%.

[0030] In the present invention, the melting point of gallium is 29.76 °C. By adding gallium to reduce the melting point of the alloy, the present invention controls the content of each element in the grain boundary phase R-Ga-M alloy within the above range to form a low-melting-point alloy mainly composed of light rare earth elements and assisted by heavy rare earth elements, which will melt into a liquid phase during vacuum sintering, facilitating liquid-phase sintering and thereby reducing the temperature of vacuum low-temperature sintering.

[0031] In a specific embodiment of the present invention, the grain boundary phase R-Ga-M alloy is preferably Pr60Ga20Dy20 (wt%), (Pr0.25Nd0.75)70Ga10Dy10Tb10 or (Pr0.2Nd0.8)60Ga20Dy10Tb10.

[0032] In the present invention, the grain boundary phase R-Ga-M alloy is preferably used in the form of an alloy casting sheet, and the thickness of the alloy casting sheet is preferably 0.1 to 0.6 mm, specifically it can be 0.1, 0.2, 0.24, 0.26, 0.3, 0.4, 0.5 or 0.6 mm. The present invention has no special limitation on the source of the alloy casting sheet. It is preferably an alloy casting sheet prepared by a kilogram-level vacuum rapid quenching furnace or a vacuum thin sheet rapid solidification furnace. The present invention has no special limitation on the specific parameters of preparing the alloy casting sheet by the kilogram-level vacuum rapid quenching furnace or the vacuum thin sheet rapid solidification furnace.

[0033] In the present invention, the temperature of the second dehydrogenation is preferably 400 to 500 °C, specifically it can be 420, 440, 450, 460, 480 or 500 °C.

[0034] In the present invention, the second crushing is preferably ball milling or hydrogen crushing. The present invention has no special limitation on the parameters of the second crushing and the time of the second dehydrogenation, as long as saturated dehydrogenation can be achieved.

[0035] After obtaining the R-Fe-B-M alloy rough material and the grain boundary phase R-Ga-M alloy rough material, the present invention mixes the R-Fe-B-M alloy rough material, the grain boundary phase R-Ga-M alloy rough material, an antioxidant, a lubricant and a dispersant, and then performs press molding under a magnetic field to obtain a blank.

[0036] In the present invention, the mass W1 of the R-Fe-B-M alloy rough material and the mass W2 of the grain boundary phase R-Ga-M alloy rough material during mixing preferably satisfy the relational expression: W2 = (0.1% - 2%) × W1, and W2 can specifically be 0.1% × W1, 0.5% × W1, 1% × W1, 1.2% × W1, 1.8% × W1 or 2% × W1.

[0037] By controlling the relationship between W1 and W2 within the above range, the present invention can obtain a low-boron series R-Fe-B permanent magnet material with a low gallium content, reduce the usage amount of gallium element, and thus reduce the production cost.

[0038] In the present invention, the sum of the contents of the antioxidant and the lubricant in the low-boron series R-Fe-B permanent magnet material is preferably 0.1 to 0.13 wt%, specifically it can be 0.11 wt% or 0.13 wt%. In a specific embodiment of the present invention, the content of the antioxidant in the low-boron series R-Fe-B permanent magnet material is 0.06 wt%, and the content of the lubricant is 0.05 wt%.

[0039] In the present invention, the content of the dispersant in the low-boron series R-Fe-B permanent magnet material is preferably 0.1 wt%.

[0040] The present invention has no special limitation on the types of the antioxidant, lubricant and dispersant, and the types and dosages well-known to those skilled in the art can be adopted.

[0041] The present invention preferably mixes the R-Fe-B-M alloy rough material and the grain boundary phase R-Ga-M alloy rough material, then adds an antioxidant and a lubricant. After uniform mixing, jet milling is carried out to control the oxygen content to 0-10 ppm. The obtained powder is further mixed with a dispersant to obtain a mixed material.

[0042] In the present invention, the average particle size of the powder is preferably 2.3-3.5 μm, and specifically can be 2.3, 2.45, 2.5, 2.6, 3 or 3.5 μm.

[0043] In the present invention, the intensity of the magnetic field is preferably 1.5-2.5 T, and specifically can be 1.5, 2 or 2.5 T.

[0044] The present invention preferably places the mixed material in an orientation magnetic field that has been filled with nitrogen and deoxygenated and has an oxygen content of 100-500 ppm (specifically can be 100, 200, 300, 400 or 500 ppm) for molding to obtain the blank.

[0045] After obtaining the blank, the present invention performs cold isostatic pressing on the blank to obtain a green compact.

[0046] In the present invention, the pressure of the cold isostatic pressing is preferably 180-220 MPa, specifically can be 180, 200 or 220 MPa, and the time is preferably 180 s.

[0047] After obtaining the green compact, the present invention sequentially performs vacuum degassing, vacuum low-temperature sintering and aging treatment on the green compact to obtain the low-boron R-Fe-B permanent magnetic material. The pressure of the vacuum low-temperature sintering is 0.05-1 MPa. The vacuum low-temperature sintering includes first vacuum low-temperature sintering, second vacuum low-temperature sintering and third vacuum low-temperature sintering in sequence. The temperature of the first vacuum low-temperature sintering is 470-580 °C, the heat preservation time of the first vacuum low-temperature sintering is 4-12 h, the temperature of the second vacuum low-temperature sintering is 650-730 °C, the heat preservation time of the second vacuum low-temperature sintering is 4-12 h, the temperature of the third vacuum low-temperature sintering is 900-1000 °C, and the heat preservation time of the third vacuum low-temperature sintering is 4-30 h.

[0048] In the present invention, the vacuum degree of the vacuum degassing is preferably lower than 9×10 -3Pa, the vacuum degassing preferably includes first vacuum degassing, second vacuum degassing and third vacuum degassing carried out in sequence. The temperature of the first vacuum degassing is preferably 330-360°C, specifically 330, 340, 350 or 360°C. The heat preservation time of the first vacuum degassing is preferably 1-4h, specifically 1, 2, 3 or 4h. The temperature of the second vacuum degassing is preferably 550-580°C, specifically 550, 560, 570 or 580°C. The heat preservation time of the second vacuum degassing is preferably 1-4h, specifically 1, 2, 3 or 4h. The temperature of the third vacuum degassing is preferably 850-880°C, specifically 850, 860, 870 or 880°C. The heat preservation time of the third vacuum degassing is preferably 1-4h, specifically 1, 2, 3 or 4h. In the present invention, it is preferred that when the vacuum degree at the previous temperature gradient resumes to be lower than 9×10 -3 Pa, then the next temperature gradient is carried out. After the degassing at the three temperature gradients is completed and the vacuum degree is lower than 9×10 -3 Pa, argon is filled and air cooling is carried out. When the temperature in the vacuum sintering furnace is lower than 100°C, then the vacuum low-temperature sintering is carried out.

[0049] In the present invention, the vacuum degassing is preferably carried out in a vacuum sintering furnace.

[0050] In the present invention, the pressure of the vacuum low-temperature sintering can specifically be 0.05, 0.1, 0.2, 0.4, 0.6, 0.8 or 1MPa.

[0051] In the present invention, the atmosphere of the vacuum low-temperature sintering is preferably a protective gas, and the protective gas is preferably argon.

[0052] In the present invention, the temperature of the first vacuum low-temperature sintering can specifically be 470, 490, 500, 520, 540, 560 or 580°C. The heat preservation time of the first vacuum low-temperature sintering can specifically be 4, 6, 8, 10 or 12h. The temperature of the second vacuum low-temperature sintering can specifically be 650, 670, 690, 700, 710, 720 or 730°C. The heat preservation time of the second vacuum low-temperature sintering can specifically be 4, 6, 8, 10 or 12h. The temperature of the third vacuum low-temperature sintering can specifically be 900, 950, 980 or 1000°C. The heat preservation time of the third vacuum low-temperature sintering can specifically be 4, 5, 8, 10, 15, 20, 25 or 30h.

[0053] After the vacuum low-temperature sintering is completed, in the present invention, it is preferred to stop heating and cool it to a temperature lower than 100°C in the vacuum sintering furnace by air cooling or argon filling and air cooling.

[0054] In the present invention, the vacuum degree of the aging treatment is preferably lower than 9×10-3 Pa. The aging treatment preferably includes a first aging treatment and a second aging treatment carried out in sequence. The temperature of the first aging treatment is preferably 880-910 °C, specifically it can be 880, 890, 900 or 910 °C. The holding time of the first aging treatment is preferably 2-4 h, specifically it can be 2, 3 or 4 h. The temperature of the second aging treatment is preferably 440-520 °C, specifically it can be 440, 450, 480, 500 or 520 °C. The holding time of the second aging treatment is preferably 2-4 h, specifically it can be 2, 3 or 4 h.

[0055] After the first aging treatment is completed, the present invention preferably stops heating, and is air-cooled or air-cooled with argon filling until the temperature is lower than 100 °C, and then the second aging treatment is carried out.

[0056] After the aging treatment is completed, the present invention preferably stops heating, and is air-cooled or air-cooled with argon filling until the temperature of the vacuum sintering furnace is lower than 80 °C, and the low-boron R-Fe-B permanent magnet material is obtained.

[0057] The present invention also provides a low-boron R-Fe-B permanent magnet material prepared by the preparation method described in the above technical solution.

[0058] In the present invention, the density of the low-boron R-Fe-B permanent magnet material is preferably greater than 7.5 g / cm 3 .

[0059] The low-boron R-Fe-B permanent magnet material of the present invention can be applied to new energy vehicles, wind power new energy, automotive energy-saving electric appliances, energy-saving household appliances, energy-saving elevators, intelligent equipment such as robots, and intelligent consumer electronics fields such as mobile phones.

[0060] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with the embodiments in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without creative efforts shall fall within the protection scope of the present invention.

[0061] In the present invention, bal means "balance".

[0062] Example 1 A preparation method of a low-boron R-Fe-B permanent magnet material includes the following steps: 1. The composition of the R-Fe-B-M alloy cast sheet is (Pr0.2Nd0.8)30FebalCu0.4Co0.5Ga0.15Zr0.2Ti0.3B0.9 (wt%). After melting the above raw material components in a vacuum thin-sheet rapid solidification furnace, an alloy cast sheet with an average thickness of 0.24 mm is prepared.

[0063] 2. The composition of the grain boundary phase R-Ga-M alloy cast sheet is Pr60Ga20Dy20 (wt%). After vacuum melting the above raw material components, an alloy cast sheet with an average thickness of 0.26 mm is prepared.

[0064] 3. The R-Fe-B-M alloy cast sheet is crushed by the hydrogen breaking process, and the dehydrogenation temperature is 500 °C to obtain the R-Fe-B-M alloy rough material.

[0065] 4. The grain boundary phase R-Ga-M alloy cast sheet is crushed by the hydrogen breaking process, and the dehydrogenation temperature is 400 °C to obtain the grain boundary phase R-Ga-M alloy rough material.

[0066] 5. Weigh the obtained R-Fe-B-M alloy rough material as weight W1, and weigh the grain boundary phase R-Ga-M alloy rough material as weight W2, where W1 and W2 satisfy the following relationship: W2 = 1.2% × W1.

[0067] 6. The weighed R-Fe-B-M alloy rough material and the grain boundary phase R-M alloy rough material are mixed, and an antioxidant (the content of the antioxidant in the low-boron R-Fe-B permanent magnet material is 0.06 wt%) and a lubricant (the content of the lubricant in the low-boron R-Fe-B permanent magnet material is 0.05 wt%) are added. After mixing evenly, the mixture is ground into powder by a jet mill, the oxygen content is controlled at 10 ppm, the average particle size of the obtained powder is 2.8 μm, and then a dispersant (the content of the dispersant in the low-boron R-Fe-B permanent magnet material is 0.1 wt%) is added for powder mixing, and the powder mixing is uniform.

[0068] 7. Weigh the powder obtained by the jet mill and put it into a 2.0 T orientation magnetic field that has been filled with nitrogen and deoxygenated and has an oxygen content of 500 ppm for molding to obtain a blank. Then, the blank after molding is subjected to cold isostatic pressing treatment (180 MPa, 180 s) to obtain a green compact.

[0069] 8. Put the green compact into a vacuum sintering furnace for degassing treatment. When the vacuum degree is lower than 9×10 -3 Pa, start heating, and carry out degassing for 1 h at three temperature gradients of 350 °C, 580 °C, and 850 °C respectively. When the vacuum degree resumes to be lower than 9×10 -3 Pa at the previous temperature gradient, then carry out the next temperature gradient. After the degassing at the three temperature gradients is completed and the vacuum degree is lower than 9×10 -3 Pa, fill with argon and air-cool, and the temperature in the vacuum sintering furnace is lower than 100 °C.

[0070] 9. The vacuum degree is lower than 9×10 -3When the pressure reaches 0.1 MPa, ultra-pure argon gas is filled and then vacuum low-temperature sintering treatment is carried out. Heating is started. After holding at 580 °C for 10 h, the temperature is further increased. After holding at 700 °C for 10 h, the temperature is further increased. After holding at 900 °C for 10 h, heating is stopped and it is air-cooled until the temperature in the vacuum sintering furnace is lower than 100 °C.

[0071] 10. Aging treatment. When the vacuum degree is lower than 9×10 -3 , heating is started, held at 890 °C for 2 h, heating is stopped, filled with argon and air-cooled, cooled to a temperature lower than 100 °C, then the temperature is further increased to 450 °C and held for 4 h, heating is stopped, filled with argon and air-cooled until the temperature in the vacuum sintering furnace is lower than 80 °C, and then the furnace door is opened to discharge the material.

[0072] 11. Measure the magnetic properties of the low-boron R-Fe-B permanent magnet material at room temperature. Remanence Br: 14.25 kGs, intrinsic coercivity Hcj: 20.80 kOe, maximum magnetic energy product (BH)max: 50.19 MGOe. The density of the prepared low-boron R-Fe-B permanent magnet material is 7.57 g / cm 3 .

[0073] Example 2 A preparation method of a low-boron R-Fe-B permanent magnet material, comprising the following steps: 1. The composition of the R-Fe-B-M alloy cast sheet is (Pr0.2Nd0.8)32FebalCu0.2Co0.5Ga0.1Ti0.15Nb0.25B0.85 (wt%). After melting the above raw material components in a vacuum thin-sheet rapid solidification furnace, an alloy cast sheet with an average thickness of 0.26 mm is prepared.

[0074] 2. The composition of the grain boundary phase R-Ga-M alloy cast sheet is (Pr0.2Nd0.8)60Ga20Dy10Tb10. After melting the above raw material components in a vacuum, an alloy cast sheet with an average thickness of 0.26 mm is prepared.

[0075] 3. The R-Fe-B-M alloy cast sheet is crushed by a hydrogenation-disproportionation process, and the dehydrogenation temperature is 560 °C to obtain the R-Fe-B-M alloy coarse material.

[0076] 4. The grain boundary phase R-Ga-M alloy cast sheet is crushed by a hydrogenation-disproportionation process, and the dehydrogenation temperature is 440 °C to obtain the grain boundary phase R-Ga-M alloy coarse material.

[0077] 5. Weigh the obtained R-Fe-B-M alloy coarse material as weight W1, and weigh the grain boundary phase R-Ga-M alloy coarse material as weight W2, where W1 and W2 satisfy the following relationship: W2 = 2% × W1.

[0078] 6. The as - weighed R - Fe - B - M alloy rough material and the grain boundary phase R - M alloy rough material are mixed, and an antioxidant (the content of the antioxidant in the low - boron R - Fe - B permanent magnetic material is 0.06 wt%) and a lubricant (the content of the lubricant in the low - boron R - Fe - B permanent magnetic material is 0.05 wt%) are added. After mixing evenly, it is ground into powder by a jet mill, the oxygen content is controlled at 10 ppm, the average particle size of the obtained powder is 2.8 μm, and then a dispersant (the content of the dispersant in the low - boron R - Fe - B permanent magnetic material is 0.1 wt%) is added for powder mixing, and the powder mixing is uniform.

[0079] 7. The powder obtained by jet milling is put into a 2.0T orientation magnetic field that has been filled with nitrogen to remove oxygen and has an oxygen content of 100 ppm for pressing and forming to obtain a blank. Then, the formed blank is subjected to cold isostatic pressing treatment (180 MPa, 180 s) to obtain a green compact.

[0080] 8. The green compact is put into a vacuum sintering furnace for degassing treatment. When the vacuum degree is lower than 9×10 -3 Pa, heating starts, and degassing is carried out for 1 h at three temperature gradients of 330 °C, 580 °C, and 860 °C respectively. When the vacuum degree returns to lower than 9×10 -3 Pa at the previous temperature gradient, the next temperature gradient is carried out. After the degassing at the three temperature gradients is completed and the vacuum degree is lower than 9×10 -3 Pa, argon is filled and air - cooled until the temperature in the vacuum sintering furnace is lower than 100 °C.

[0081] 9. When the vacuum degree is lower than 9×10 -3 Pa, ultra - pure argon gas is filled at 0.2 MPa and then vacuum low - temperature sintering treatment is carried out. Heating starts, it is kept at 580 °C for 10 h, then continues to heat up, kept at 720 °C for 10 h, then continues to heat up, kept at 980 °C for 10 h, then stops heating, and is air - cooled until the temperature in the vacuum sintering furnace is lower than 100 °C.

[0082] 10. Aging treatment: When the vacuum degree is lower than 9×10 -3 , heating starts, it is kept at 880 °C for 2 h, then stops heating, argon is filled and air - cooled, cooled to a temperature lower than 100 °C, then continues to heat up to 440 °C and kept for 4 h, then stops heating, argon is filled and air - cooled until the temperature in the vacuum sintering furnace is lower than 80 °C, and then the furnace door is opened to take out the material.

[0083] 11. Measure the magnetic properties of the low - boron R - Fe - B permanent magnetic material magnet at room temperature. Remanence Br: 14.20 kGs, intrinsic coercivity Hcj: 25.32 kOe, maximum magnetic energy product (BH)max: 50.08 MGOe. The density of the obtained low - boron R - Fe - B permanent magnetic material is 7.55 g / cm 3 .

[0084] Example 3 A preparation method of a low-boron R-Fe-B permanent magnet material, comprising the following steps: 1. The composition of the R-Fe-B-M alloy ingot is (Pr0.25Nd0.75)33FebalCu0.3Co0.5Ga0.15Ti0.2Nb0.25B0.85 (wt%). After melting the above raw material components in a vacuum thin-sheet rapid solidification furnace, an alloy ingot with an average thickness of 0.22 mm is prepared.

[0085] 2. The composition of the grain boundary phase R-Ga-M alloy ingot is (Pr0.25Nd0.75)70Ga10Dy10Tb10. After vacuum melting the above raw material components, an alloy ingot with an average thickness of 0.24 mm is prepared.

[0086] 3. The R-Fe-B-M alloy ingot is crushed by a hydrogen breaking process, and the dehydrogenation temperature is 580 °C to obtain the R-Fe-B-M alloy coarse material.

[0087] 4. The grain boundary phase R-Ga-M alloy ingot is crushed by a hydrogen breaking process, and the dehydrogenation temperature is 450 °C to obtain the grain boundary phase R-Ga-M alloy coarse material.

[0088] 5. Weigh the obtained R-Fe-B-M alloy coarse material as weight W1, and weigh the grain boundary phase R-Ga-M alloy coarse material as weight W2, where W1 and W2 satisfy the following relationship: W2 = 2% × W1.

[0089] 6. The weighed R-Fe-B-M alloy coarse material and the grain boundary phase R-M alloy coarse material are mixed, and an antioxidant (the content of the antioxidant in the low-boron R-Fe-B permanent magnet material is 0.06 wt%) and a lubricant (the content of the lubricant in the low-boron R-Fe-B permanent magnet material is 0.05 wt%) are added. After mixing evenly, it is ground into powder by a jet mill, the oxygen content is controlled at 10 ppm, the average particle size of the obtained powder is 2.8 μm, and then a dispersant (the content of the dispersant in the low-boron R-Fe-B permanent magnet material is 0.1 wt%) is added for powder mixing, and the powder mixing is uniform.

[0090] 7. Put the powder obtained by the jet mill into a 2.0 T orientation magnetic field that has been filled with nitrogen and deoxygenated and has an oxygen content of 100 ppm for molding to obtain a blank, and then the blank after molding is subjected to cold isostatic pressing treatment (180 MPa, 180 s) to obtain a green compact.

[0091] 8. Put the green compact into a vacuum sintering furnace for degassing treatment. When the vacuum degree is lower than 9×10 -3 Pa, start heating, and perform degassing for 1 h at three temperature gradients of 330 °C, 560 °C, and 850 °C respectively. When the vacuum degree returns to lower than 9×10 -3When the pressure reaches [specific value] Pa, proceed to the next temperature gradient. After the degassing at the three temperature gradients is completed, if the vacuum degree is lower than 9×10 -3 Pa, fill with argon and cool with air until the temperature in the vacuum sintering furnace is lower than 100°C.

[0092] 9. When the vacuum degree is lower than 9×10 -3 Pa, fill with ultra-pure argon at 0.2 MPa and then carry out vacuum low-temperature sintering treatment. Start heating, keep the temperature at 580°C for 8 hours, then continue to heat up. Keep the temperature at 700°C for 8 hours, then continue to heat up. Keep the temperature at 980°C for 8 hours, then stop heating and cool with air until the temperature in the vacuum sintering furnace is lower than 100°C.

[0093] 10. Aging treatment: When the vacuum degree is lower than 9×10 -3 , start heating, keep the temperature at 850°C for 2 hours, then stop heating, fill with argon and cool with air until the temperature is lower than 100°C. Then continue to heat up to 460°C and keep it for 4 hours, stop heating, fill with argon and cool with air until the temperature in the vacuum sintering furnace is lower than 80°C, and then open the furnace door to take out the material.

[0094] 11. Measure the magnetic properties of the low-boron R-Fe-B permanent magnet material at room temperature. Remanence Br: 14.15 kGs, intrinsic coercivity Hcj: 25.20 kOe, maximum magnetic energy product (BH)max: 50.10 MGOe. The density of the prepared low-boron R-Fe-B permanent magnet material is 7.60 g / cm 3 .

[0095] Example 4 A preparation method of a low-boron R-Fe-B permanent magnet material, comprising the following steps: 1. The composition of the R-Fe-B-M alloy cast sheet is (Pr0.25Nd0.75)29.5Ce1.5FebalCu0.4Co0.8Ga0.15Zr0.15Nb0.2B0.9 (wt%). After melting the above raw material components in a vacuum thin-sheet rapid solidification furnace, alloy cast sheets with an average thickness of 0.24 mm are prepared.

[0096] 2. The composition of the grain boundary phase R-Ga-M alloy cast sheet is Pr60Ga20Dy20 (wt%). After melting the above raw material components in a vacuum, alloy cast sheets with an average thickness of 0.24 mm are prepared.

[0097] 3. The R-Fe-B-M alloy cast sheet is crushed by the hydrogen breaking process, and the dehydrogenation temperature is 560°C to obtain the R-Fe-B-M alloy coarse material.

[0098] 4. The grain boundary phase R-Ga-M alloy cast sheet is crushed by the hydrogen breaking process, and the dehydrogenation temperature is 480°C to obtain the grain boundary phase R-Ga-M alloy coarse material.

[0099] 5. Weigh the obtained R-Fe-B-M alloy rough material with a weight of W1, and weigh the grain boundary phase R-Ga-M alloy rough material with a weight of W2, where W1 and W2 satisfy the following relationship: W2 = 1.8% × W1.

[0100] 6. Mix the weighed R-Fe-B-M alloy rough material and the grain boundary phase R-M alloy rough material, and add an antioxidant (the content of the antioxidant in the low-boron R-Fe-B permanent magnetic material is 0.06 wt%) and a lubricant (the content of the lubricant in the low-boron R-Fe-B permanent magnetic material is 0.05 wt%). After mixing evenly, grind the mixture into powder by a jet mill, control the oxygen content to 10 ppm, and the average particle size of the obtained powder is 2.8 μm. Then add a dispersant (the content of the dispersant in the low-boron R-Fe-B permanent magnetic material is 0.1 wt%) to mix the powder evenly.

[0101] 7. Put the powder obtained by the jet mill into a 2.0 T orientation magnetic field that has been purged with nitrogen and has an oxygen content of 100 ppm for molding to obtain a blank. Then, subject the molded blank to cold isostatic pressing treatment (180 MPa, 180 s) to obtain a green compact.

[0102] 8. Put the green compact into a vacuum sintering furnace for degassing treatment. When the vacuum degree is lower than 9×10 -3 Pa, start heating, and perform degassing for 1 h at three temperature gradients of 350 °C, 560 °C, and 850 °C respectively. When the vacuum degree returns to lower than 9×10 -3 Pa at the previous temperature gradient, then proceed to the next temperature gradient. After the outgassing at the three temperature gradients is completed and the vacuum degree is lower than 9×10 -3 Pa, fill with argon and air-cool until the temperature in the vacuum sintering furnace is lower than 100 °C.

[0103] 9. When the vacuum degree is lower than 9×10 -3 Pa, fill with ultra-pure argon at 0.2 MPa and then perform vacuum low-temperature sintering treatment. Start heating, hold at 560 °C for 8 h, then continue to heat up, hold at 720 °C for 8 h, then continue to heat up, hold at 950 °C for 8 h, then stop heating, and air-cool until the temperature in the vacuum sintering furnace is lower than 100 °C.

[0104] 10. Aging treatment: When the vacuum degree is lower than 9×10 -3 , start heating, hold at 890 °C for 2 h, then stop heating, fill with argon and air-cool until the temperature is lower than 100 °C. Then continue to heat up to 480 °C and hold for 4 h, stop heating, fill with argon and air-cool until the temperature in the vacuum sintering furnace is lower than 80 °C, and then open the furnace door to discharge the material.

[0105] 11. Measure the magnetic properties of the low-boron R-Fe-B permanent magnet material at room temperature. The remanence Br is 14.10 kGs, the intrinsic coercivity Hcj is 20.12 kOe, and the maximum magnetic energy product (BH)max is 50.15 MGOe. The density of the prepared low-boron R-Fe-B permanent magnet material is 7.58 g / cm 3 .

[0106] The above are only the preferred embodiments of the present invention and do not impose any formal restrictions on the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A preparation method of a low-boron R-Fe-B permanent magnetic material, characterized in that It includes the following steps: The R-Fe-B-M alloy is first crushed and then dehydrogenated for the first time to obtain a R-Fe-B-M alloy rough material; in the R-Fe-B-M alloy, R is a rare earth element, including one or more of Nd, Pr, La, Ce, Y, and Sm, and M includes one or more of Cu, Al, Co, Ga, Ni, Ti, Nb, Zr, Ge, Zn, Sn, Ag, V, Cr, Mn, W, Mo, and Si. The content of R in the R-Fe-B-M alloy is 29wt% - 36wt%, and the content of B element is 0.8wt% - 0.96wt%. The grain boundary phase R-Ga-M alloy is first crushed and then dehydrogenated for the second time to obtain a grain boundary phase R-Ga-M alloy rough material; in the grain boundary phase R-Ga-M alloy, R is a rare earth element, including one or more of Nd, Pr, La, Ce, and Sm, and M includes one or more of Dy, Tb, Gd, Y, and Ho. The content of R in the grain boundary phase R-Ga-M alloy is 60wt% - 90wt%, the content of Ga element is 10wt% - 20wt%, and the content of M element is 0wt% - 30wt% and not 0wt%. The R-Fe-B-M alloy rough material, the grain boundary phase R-Ga-M alloy rough material, an antioxidant, a lubricant, and a dispersant are mixed, and then pressed and formed under a magnetic field to obtain a blank. The blank is subjected to cold isostatic pressing to obtain a green compact. The green compact is successively subjected to vacuum degassing, vacuum low-temperature sintering, and aging treatment to obtain the low-boron series R-Fe-B permanent magnet material. The pressure of the vacuum low-temperature sintering is 0.05 - 1MPa. The vacuum low-temperature sintering includes first vacuum low-temperature sintering, second vacuum low-temperature sintering, and third vacuum low-temperature sintering in sequence. The temperature of the first vacuum low-temperature sintering is 470 - 580°C, the holding time of the first vacuum low-temperature sintering is 4 - 12h, the temperature of the second vacuum low-temperature sintering is 650 - 730°C, the holding time of the second vacuum low-temperature sintering is 4 - 12h, the temperature of the third vacuum low-temperature sintering is 900 - 1000°C, and the holding time of the third vacuum low-temperature sintering is 4 - 30h.

2. The preparation method according to claim 1, wherein When mixing, the mass W1 of the R-Fe-B-M alloy rough material and the mass W2 of the grain boundary phase R-Ga-M alloy rough material satisfy the relationship: W2 = (0.1% - 2%) × W1.

3. The preparation method according to claim 1, wherein The content of M element in the R-Fe-B-M alloy is 1wt% - 2wt%, and the balance is Fe element and inevitable impurities; when M in the R-Fe-B-M alloy includes one or more of Ga, Ge, Zn, Sn, Ag, and Si, the contents of Ga, Ge, Zn, Sn, Ag, and Si in the R-Fe-B-M alloy are independently 0wt% - 0.20wt% and not 0wt%.

4. The preparation method according to claim 1, characterized in that, The temperature of the first dehydrogenation is 320 - 580°C.

5. The preparation method according to claim 1, wherein The temperature of the second dehydrogenation is 400 - 500°C.

6. The preparation method according to claim 1, characterized in that, The degree of vacuum for the vacuum degassing is lower than 9×10 - 3 Pa. The vacuum degassing includes first vacuum degassing, second vacuum degassing, and third vacuum degassing carried out in sequence. The temperature of the first vacuum degassing is 330 - 360°C, the heat preservation time of the first vacuum degassing is 1 - 4 h, the temperature of the second vacuum degassing is 550 - 580°C, the heat preservation time of the second vacuum degassing is 1 - 4 h, the temperature of the third vacuum degassing is 850 - 880°C, and the heat preservation time of the third vacuum degassing is 1 - 4 h.

7. The preparation method according to claim 1, wherein The vacuum degree of the aging treatment is lower than 9×10 - 3 Pa. The aging treatment includes a first aging treatment and a second aging treatment carried out in sequence. The temperature of the first aging treatment is 880-910°C, the heat preservation time of the first aging treatment is 2-4h, the temperature of the second aging treatment is 440-520°C, and the heat preservation time of the second aging treatment is 2-4h.

8. The preparation method according to claim 1, characterized in that, The pressure of the cold isostatic pressing is 180 - 220MPa.

9. The preparation method according to claim 1, characterized in that, The intensity of the magnetic field is 1.5 - 2.5 T.

10. A low-boron R-Fe-B permanent magnet material prepared by the preparation method according to any one of claims 1 to 9.