A R-Fe-B permanent magnetic material and its preparation method

Abstract

The present invention provides a kind of R-Fe-B system permanent magnet material and preparation method thereof, belong to the technical field of rare earth permanent magnet material. The present invention performs hydrogen cracking and dehydrogenation on the first main phase R-Fe-B-M alloy, the second main phase R-Fe-B-M alloy and the grain boundary phase R-Ga-M alloy respectively in sequence, obtains the coarse material and mixes it with antioxidant, lubricant and dispersant, then performs compression molding, the obtained blank is subjected to cold isostatic pressing treatment, the obtained pressed green is subjected to vacuum degassing, vacuum sintering and aging treatment in sequence, and obtains the R-Fe-B system permanent magnet material. The present invention adopts a dual-main phase system, combines the grain boundary phase R-Ga-M alloy, and the grain boundary phase R-Ga-M alloy can form a low-melting-point alloy based on light rare earth elements, is beneficial to liquid phase sintering, promotes magnet densification, and then can improve intrinsic coercivity without adding heavy rare earth elements Dy and Tb, and without the need for grain boundary diffusion process.

Description

Technical Field

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

[0002] Nd-Fe-B rare earth permanent magnets, known as the "King of Magnets," are widely used in new energy vehicles, high-end electronic components, and other fields due to their excellent magnetic properties and relatively low price. The rapid promotion and popularization of emerging technologies such as new energy vehicles, energy-saving motors, wind turbines, energy-saving home appliances, and industrial robots has significantly increased demand for Nd-Fe-B rare earth permanent magnets. At the same time, downstream application scenarios for Nd-Fe-B rare earth permanent magnets continue to expand. The gradual maturity of technologies such as 5G and the Internet of Things is making smart homes, smart travel, and smart entertainment a reality. Potential growth areas for future demand, such as humanoid robots, are also emerging.

[0003] The related process for producing high-performance NdFeB sintered magnets requires large amounts of doping with heavy rare earth elements (Dy and Tb) to achieve high coercivity. However, Dy and Tb are scarce in rare earth minerals and have high market prices. In addition, heavy rare earth elements Dy and Tb form ferrimagnetic coupling with the Fe element in the magnet grains. Large amounts of doping can significantly reduce the remanence and maximum magnetic energy product. Therefore, the production of high-performance NdFeB sintered magnets mostly uses the grain boundary diffusion process, which can significantly reduce the use of heavy rare earth elements. However, the grain boundary diffusion process includes surface impregnation, electrophoretic deposition, evaporation and magnetron sputtering, requiring specialized equipment and huge investment. Summary of the Invention

[0004] In view of this, the present invention aims to provide an R-Fe-B permanent magnet material and a preparation method thereof. The preparation method of the present invention does not require the addition of heavy rare earth elements Dy and Tb, nor does it require a grain boundary diffusion process, and can improve the intrinsic coercivity of the R-Fe-B permanent magnet material.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a method for preparing an R-Fe-B permanent magnetic material, wherein the R-Fe-B permanent magnetic material does not contain heavy rare earth elements Dy and Tb, comprising the following steps:

[0007] The first main phase R-Fe-BM alloy is subjected to a first hydrogen cracking and a first dehydrogenation in sequence to obtain a first main phase R-Fe-BM alloy coarse material; in the first main phase R-Fe-BM 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;

[0008] The second main phase R-Fe-BM alloy is subjected to a second hydrogen cracking and a second dehydrogenation in sequence to obtain a second main phase R-Fe-BM alloy coarse material; in the second main phase R-Fe-BM 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;

[0009] The grain boundary phase R-Ga-M alloy is subjected to a third hydrogen cracking and a third dehydrogenation in sequence to obtain a grain boundary phase R-Ga-M alloy coarse 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 Cu, Al, Ge, Zn, Sn, Ag and Si, and the content of R in the grain boundary phase R-Ga-M alloy is 60wt%-90wt%, the content of Ga is 10wt%-20wt%, and the content of M is 0wt%-30wt% and is not 0wt%;

[0010] The first main phase R-Fe-BM alloy coarse material, the second main phase R-Fe-BM alloy coarse material, the grain boundary phase R-Ga-M alloy coarse material, an antioxidant, a lubricant and a dispersant are mixed, and then pressed under a magnetic field to obtain a blank;

[0011] The blank is subjected to cold isostatic pressing to obtain a compact;

[0012] The compact is subjected to vacuum degassing, vacuum sintering and aging treatment in sequence to obtain the R-Fe-B permanent magnetic material.

[0013] Preferably, during the mixing, the mass W1 of the first main phase R-Fe-BM alloy coarse material, the mass W2 of the second main phase R-Fe-BM alloy coarse material, and the mass W3 of the grain boundary phase R-Ga-M alloy coarse material satisfy the relationship:

[0014] W1: W2= (4~9): (1~6);

[0015] W3=(0.1%~8%)×(W1+W2).

[0016] Preferably, the content of R in the first main phase R-Fe-BM alloy is 28wt%~31wt%, the content of B element is 0.93wt%~1.03wt%, the content of M element is 1wt%~2wt%, and the balance is Fe element and unavoidable impurities; when M in the first main phase R-Fe-BM 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 first main phase R-Fe-BM alloy are independently 0wt%~0.25wt% and not 0wt%.

[0017] Preferably, the content of R in the second main phase R-Fe-BM alloy is 30wt%~36.5wt%, the content of B element is 0.8wt%~0.95wt%, the content of M element is 1wt%~3wt%, and the balance is Fe element and inevitable impurities; when M in the second main phase R-Fe-BM 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 second main phase R-Fe-BM alloy are independently 0.25wt%~0.56wt%.

[0018] Preferably, the temperature of the first dehydrogenation is 500-580°C; the temperature of the second dehydrogenation is 320-520°C; and the temperature of the third dehydrogenation is 320-520°C.

[0019] Preferably, the vacuum degree of the vacuum degassing is lower than 9×10 -3 Pa, the vacuum degassing includes a first vacuum degassing, a second vacuum degassing and a third vacuum degassing performed in sequence, the temperature of the first vacuum degassing is 330~360℃, the insulation time of the first vacuum degassing is 1~4h, the temperature of the second vacuum degassing is 550~580℃, the insulation time of the second vacuum degassing is 1~4h, the temperature of the third vacuum degassing is 850~880℃, and the insulation time of the third vacuum degassing is 1~4h.

[0020] Preferably, the vacuum degree of the vacuum sintering is lower than 9×10 -3 Pa, temperature is 1000~1100℃, and time is 3~6h.

[0021] Preferably, 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 performed sequentially, the temperature of the first aging treatment is 880-910°C, the holding time of the first aging treatment is 2-4 hours, the temperature of the second aging treatment is 440-520°C, and the holding time of the second aging treatment is 2-4 hours.

[0022] Preferably, the intensity of the magnetic field is 1.5~2.5T.

[0023] The present invention also provides an R-Fe-B permanent magnetic material prepared by the preparation method described in the above technical solution.

[0024] The present invention provides a preparation method of an R-Fe-B permanent magnet material, wherein the R-Fe-B permanent magnet material does not contain heavy rare earth elements Dy and Tb, and comprises the following steps: sequentially performing a first hydrogen cracking and a first dehydrogenation on a first main phase R-Fe-BM alloy to obtain a first main phase R-Fe-BM alloy coarse material; wherein R in the first main phase R-Fe-BM alloy is a rare earth element, including one or more of Nd, Pr, La, Ce, Y and Sm, and M includes Cu, Al, Co, Ga, Ni, Ti, N b, Zr, Ge, Zn, Sn, Ag, V, Cr, Mn, W, Mo and Si; the second main phase R-Fe-BM alloy is subjected to a second hydrogen cracking and a second dehydrogenation in sequence to obtain a second main phase R-Fe-BM alloy coarse material; in the second main phase R-Fe-BM alloy, R is a rare earth element, including one or more of Nd, Pr, La, Ce, Y and Sm, and M includes Cu, Al, Co, Ga, Ni, Ti, Nb, Zr, Ge, Zn, Sn, Ag, V, C r, Mn, W, Mo and Si; the grain boundary phase R-Ga-M alloy is subjected to a third hydrogen cracking and a third dehydrogenation in sequence to obtain a grain boundary phase R-Ga-M alloy coarse 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 Cu, Al, Ge, Zn, Sn, Ag and Si, and the content of R in the grain boundary phase R-Ga-M alloy is 60wt%~90wt%, and the content of Ga element is 10wt%~20wt%, the content of M element is 0wt%~30wt% and is not 0wt%; the first main phase R-Fe-BM alloy coarse material, the second main phase R-Fe-BM alloy coarse material, the grain boundary phase R-Ga-M alloy coarse material, an antioxidant, a lubricant and a dispersant are mixed, and then pressed under a magnetic field to obtain a blank; the blank is subjected to cold isostatic pressing to obtain a compact; the compact is sequentially subjected to vacuum degassing, vacuum sintering and aging treatment to obtain the R-Fe-B permanent magnet material.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention utilizes a dual-phase system (comprising a first-phase R-Fe-BM alloy and a second-phase R-Fe-BM alloy) combined with a grain boundary phase R-Ga-M alloy. This grain boundary phase R-Ga-M alloy forms a low-melting-point alloy primarily composed of light rare earth elements. During vacuum sintering, it melts into a liquid phase, facilitating liquid-phase sintering and promoting magnet densification. This enhances the intrinsic coercivity of R-Fe-B permanent magnets without the addition of heavy rare earth elements (Dy and Tb) or the need for grain boundary diffusion. Furthermore, the preparation method of the present invention does not utilize heavy rare earth element (Dy and Tb) diffusion sources, thus eliminating the need for additional grain boundary diffusion processes and limiting the thickness of the magnet. This differs from related art methods, which require the sintered and aged magnet to be machined into a specific-shaped diffusion substrate (less than 8 mm thick), treated with traditional grain boundary diffusion processes (such as surface impregnation, electrophoretic deposition, evaporation, and magnetron sputtering), and then subjected to a long diffusion process. The preparation method of the present invention can not only prepare magnets with high coercivity, but also has no limitation on the thickness of the R-Fe-B permanent magnet material and does not require the addition of special grain boundary diffusion equipment. The entire preparation process is short and easy to operate, suitable for large-scale industrial production, and reduces production costs.

[0027] The data of the examples show that the present invention does not utilize heavy rare earth element diffusion sources (Dy and Tb) and does not perform grain boundary diffusion, but achieves the intrinsic coercivity Hcj ≥ 20 kOe of the R-Fe-B permanent magnet material without heavy rare earth elements by adding grain boundary phase R-Ga-M alloy.

[0028] The present invention also provides an R-Fe-B permanent magnet material prepared by the preparation method described in the above technical solution. The 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 equipment, energy-saving home appliances, energy-saving elevators, robots and other intelligent equipment as well as smart consumer electronics such as mobile phones. DETAILED DESCRIPTION

[0029] The present invention provides a method for preparing an R-Fe-B permanent magnetic material, wherein the R-Fe-B permanent magnetic material does not contain heavy rare earth elements Dy and Tb, comprising the following steps:

[0030] The first main phase R-Fe-BM alloy is subjected to a first hydrogen cracking and a first dehydrogenation in sequence to obtain a first main phase R-Fe-BM alloy coarse material; in the first main phase R-Fe-BM 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;

[0031] The second main phase R-Fe-BM alloy is subjected to a second hydrogen cracking and a second dehydrogenation in sequence to obtain a second main phase R-Fe-BM alloy coarse material; in the second main phase R-Fe-BM 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;

[0032] The grain boundary phase R-Ga-M alloy is subjected to a third hydrogen cracking and a third dehydrogenation in sequence to obtain a grain boundary phase R-Ga-M alloy coarse 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 Cu, Al, Ge, Zn, Sn, Ag and Si, and the content of R in the grain boundary phase R-Ga-M alloy is 60wt%-90wt%, the content of Ga is 10wt%-20wt%, and the content of M is 0wt%-30wt% and is not 0wt%;

[0033] The first main phase R-Fe-BM alloy coarse material, the second main phase R-Fe-BM alloy coarse material, the grain boundary phase R-Ga-M alloy coarse material, an antioxidant, a lubricant and a dispersant are mixed, and then pressed under a magnetic field to obtain a blank;

[0034] The blank is subjected to cold isostatic pressing to obtain a compact;

[0035] The compact is subjected to vacuum degassing, vacuum sintering and aging treatment in sequence to obtain the R-Fe-B permanent magnetic material.

[0036] In the present invention, unless otherwise specified, the raw materials used are all commercially available products in the art or raw materials prepared by conventional preparation methods in the art.

[0037] The present invention sequentially performs a first hydrogen cracking and a first dehydrogenation on a first main phase R-Fe-BM alloy to obtain a first main phase R-Fe-BM alloy coarse material; in the first main phase R-Fe-BM 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.

[0038] In the present invention, the content of R in the first main phase R-Fe-BM alloy is preferably 28wt%~31wt%, specifically 28wt%, 29wt%, 29.5wt%, 30wt% or 31wt%; the content of B element is preferably 0.93wt%~1.03wt%, specifically 0.93wt%, 0.96wt%, 0.98wt%, 1wt% or 1.03wt%; the content of M element is preferably 1wt%~2wt%, specifically 1wt%, 1.85wt% or 2wt%; by limiting the contents of the R and B elements within the above range, R2Fe14B permanent magnet materials can be obtained, which have a wider range of applications. Limiting the content of the M element within the above range can control the content of other elements and reduce the impact on magnetic properties.

[0039] In the present invention, when M in the first main phase R-Fe-BM 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 first main phase R-Fe-BM alloy are independently preferably 0wt%~0.25wt% and not 0wt%, specifically 0.1wt%, 0.15wt% or 0.25wt%. Limiting the Ga content within the above range can make the first main phase R-Fe-BM alloy a low gallium alloy, provide a high main phase component ratio, and enable the dual main phase system of the present invention to have high remanence and high magnetic energy product performance characteristics, while suppressing the tendency of the main phase components of the dual main phase system of the present invention to decompose during the aging process.

[0040] In a specific embodiment of the present invention, the first main phase R-Fe-BM alloy is preferably Nd28FebalCu0.2Co1Ga0.15Zr0.2Nb0.3B1 (wt%), (Pr0.25Nd0.75)29.5FebalCu0.2Co1.2Ga0.1Zr0.15Nb0.2B0.98 (wt%), (Pr0.2Nd0.8)29FebalCu0.2Co1Ga0.15Zr0.25Nb0.1B0.96 (wt%) or (Pr0.2Nd0.8)28Ce1.5FebalCu0.1Co1Ga0.15Zr0.25Nb0.15B1 (wt%).

[0041] In the present invention, the first main phase R-Fe-BM alloy is preferably used in the form of an alloy casting sheet. The thickness of the alloy casting sheet is preferably 0.15~0.4mm, specifically 0.15, 0.2, 0.26, 0.28, 0.3 or 0.4mm. The present invention has no special limitation on the source of the alloy casting sheet. It is preferred that the alloy casting sheet be prepared by a vacuum thin sheet rapid solidification furnace. The present invention has no special limitation on the specific parameters of the vacuum thin sheet rapid solidification furnace for preparing the alloy casting sheet.

[0042] In the present invention, the temperature of the first dehydrogenation is preferably 500-580°C, specifically 500, 510, 520, 530, 540, 550, 560, 570 or 580°C.

[0043] The present invention has no particular limitation on the parameters of the first hydrogen breakdown and the time of the first dehydrogenation, as long as saturated dehydrogenation can be achieved.

[0044] The present invention sequentially performs second hydrogen cracking and second dehydrogenation on a second main phase R-Fe-BM alloy to obtain a second main phase R-Fe-BM alloy coarse material; in the second main phase R-Fe-BM 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.

[0045] In the present invention, the content of R in the second main phase R-Fe-BM alloy is preferably 30wt%~36.5wt%, specifically 30wt%, 32wt%, 35wt% or 36.5wt%; the content of B element is preferably 0.8wt%~0.95wt%, specifically 0.8wt%, 0.85wt%, 0.9wt% or 0.95wt%; the content of M element is preferably 1wt%~3wt%, specifically 1wt%, 1.8wt% or 3wt%, and the balance is Fe element and unavoidable impurities; limiting the content within the above range can make the rare earth element excessive, reduce the main phase ratio of the first main phase R-Fe-BM alloy and the second main phase R-Fe-BM alloy, and increase the proportion of the grain boundary phase R-Ga-M alloy.

[0046] In the present invention, when M in the second main phase R-Fe-BM 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 second main phase R-Fe-BM alloy are independently preferably 0.25wt% to 0.56wt%, specifically 0.25wt%, 0.3wt%, 0.4wt%, 0.5wt% or 0.56wt%. Limiting the Ga content within the above range can make the second main phase R-Fe-BM alloy a high gallium alloy. The dual main phase system in the present invention can produce RE6Fe during the preparation process. 13 The Ga non-magnetic phase reduces the iron content in the continuous grain boundary region, realizes magnetic decoupling of adjacent main phase grains, and improves the coercive force performance of the dual main phase system of the present invention.

[0047] In a specific embodiment of the present invention, the second main phase R-Fe-BM alloy is preferably (Pr0.2Nd0.8)32FebalCu0.2Al0.2Co0.5Ga0.50Ti0.15Nb0.25B0.9 (wt%), (Pr0.25Nd0.75)35FebalCu0.2Al0.2Co0.5Ga0.50Ti0.15Nb0.25B0.8 (wt%) or (Pr0.2Nd0.8)32FebalCu0.2Al0.2Co0.5Ga0.52Ti0.2Nb0.3B0.9 (wt%).

[0048] In the present invention, the second main phase R-Fe-BM alloy is preferably used in the form of an alloy casting sheet. The thickness of the alloy casting sheet is preferably 0.15~0.4 mm, specifically 0.15, 0.2, 0.26, 0.28, 0.3 or 0.4 mm. The present invention has no special limitation on the source of the alloy casting sheet. It is preferred that the alloy casting sheet be prepared by a vacuum thin sheet rapid solidification furnace. The present invention has no special limitation on the specific parameters of the vacuum thin sheet rapid solidification furnace for preparing the alloy casting sheet.

[0049] In the present invention, the temperature of the second dehydrogenation is preferably 320-520°C, specifically 320, 360, 400, 440, 480 or 520°C.

[0050] The present invention has no particular limitation on the parameters of the second hydrogen breakdown and the time of the second dehydrogenation, as long as saturated dehydrogenation can be achieved.

[0051] The present invention sequentially performs a third hydrogen cracking and a third dehydrogenation on a grain boundary phase R-Ga-M alloy to obtain a grain boundary phase R-Ga-M alloy coarse 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 Cu, Al, Ge, Zn, Sn, Ag and Si; the content of R in the grain boundary phase R-Ga-M alloy is 60wt%-90wt%, the content of Ga is 10wt%-20wt%, and the content of M is 0wt%-30wt% and is not 0wt%.

[0052] 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 be specifically 10wt%, 15wt% or 20wt%; the content of M element can be specifically 5wt%, 10wt%, 15wt%, 20wt%, 25wt% or 30wt%.

[0053] In the present invention, the melting point of gallium is 29.76°C. By adding gallium to lower 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-mentioned range to form a low-melting-point alloy mainly composed of light rare earth elements. During the vacuum sintering process, it will melt into a liquid phase, which is beneficial to liquid phase sintering and promotes magnet densification. In addition, the intrinsic coercive force of the R-Fe-B permanent magnet material can be improved without adding heavy rare earth elements Dy and Tb and without the need for a grain boundary diffusion process.

[0054] In a specific embodiment of the present invention, the grain boundary phase R-Ga-M alloy is preferably Pr60Ga20Cu20 (wt%), Pr60Ga20Cu15Al5 (wt%) or (Pr0.2Nd0.8)70Ga20Cu5Al5 (wt%).

[0055] In the present invention, the grain boundary phase R-Ga-M alloy is preferably used in the form of an alloy casting sheet. The thickness of the alloy casting sheet is preferably 0.15~0.4mm, specifically 0.15, 0.2, 0.26, 0.28, 0.3 or 0.4mm. The present invention has no special limitation on the source of the alloy casting sheet. It is preferred that the alloy casting sheet be prepared by a kilogram-grade vacuum rapid quenching furnace or a vacuum thin-sheet rapid solidification furnace. The present invention has no special limitation on the specific parameters of the kilogram-grade vacuum rapid quenching furnace or the vacuum thin-sheet rapid solidification furnace for preparing the alloy casting sheet.

[0056] In the present invention, the temperature of the third dehydrogenation is preferably 320-520°C, specifically 320, 360, 400, 440, 480 or 520°C.

[0057] The present invention has no particular limitation on the parameters of the third hydrogen breakdown and the time of the third dehydrogenation, as long as saturated dehydrogenation can be achieved.

[0058] After obtaining the first main phase R-Fe-BM alloy coarse material, the second main phase R-Fe-BM alloy coarse material and the grain boundary phase R-Ga-M alloy coarse material, the present invention mixes the first main phase R-Fe-BM alloy coarse material, the second main phase R-Fe-BM alloy coarse material, the grain boundary phase R-Ga-M alloy coarse material, an antioxidant, a lubricant and a dispersant, and then presses them under a magnetic field to obtain a blank.

[0059] In the present invention, the mass W1 of the first main phase R-Fe-BM alloy coarse material, the mass W2 of the second main phase R-Fe-BM alloy coarse material, and the mass W3 of the grain boundary phase R-Ga-M alloy coarse material during mixing preferably satisfy the relationship:

[0060] W1:W2=(4~9):(1~6), W1:W2 can be 4:6, 5:5, 6:4, 7.5:2.5, 7:3, 8:2 or 9:1;

[0061] W3 = (0.1%~8%)×(W1+W2), where W3 can specifically be 0.1%×(W1+W2), 1.2%×(W1+W2), 2%×(W1+W2), 4%×(W1+W2), 6%×(W1+W2) or 8%×(W1+W2).

[0062] The present invention controls the relationship between W1, W2 and W3 within the above range to obtain an R-Fe-B permanent magnet material with high remanence, high intrinsic coercivity and high magnetic energy product.

[0063] In the present invention, the sum of the contents of the antioxidant and the lubricant in the R-Fe-B permanent magnet material is preferably 0.1-0.13wt%, specifically 0.11wt% or 0.13wt%. In a specific embodiment of the present invention, the content of the antioxidant in the R-Fe-B permanent magnet material is 0.06wt%, and the content of the lubricant is 0.05wt%.

[0064] In the present invention, the content of the dispersant in the R-Fe-B permanent magnetic material is preferably 0.1 wt %.

[0065] The present invention has no particular limitation on the types of the antioxidant, lubricant and dispersant, and any type and amount known to those skilled in the art may be used.

[0066] The present invention preferably mixes the first main phase R-Fe-BM alloy coarse material, the second main phase R-Fe-BM alloy coarse material and the grain boundary phase R-Ga-M alloy coarse material, then adds an antioxidant and a lubricant, and after uniform mixing, performs air flow grinding to pulverize the material, controls the oxygen content to 0~10ppm, and then mixes the obtained powder with a dispersant to obtain a mixture.

[0067] In the present invention, the average particle size of the powder is preferably 2.0-3.5 μm, specifically 2.0, 2.5, 2.6, 3 or 3.5 μm.

[0068] In the present invention, the intensity of the magnetic field is preferably 1.5-2.5T, specifically 1.5, 2 or 2.5T.

[0069] In the present invention, the mixed material is preferably placed in an oriented magnetic field that is filled with nitrogen and deoxygenated and has an oxygen content of 100 to 500 ppm (specifically, 100, 200, 300, 400 or 500 ppm) for compression molding to obtain the blank.

[0070] After obtaining the blank, the present invention performs cold isostatic pressing on the blank to obtain a pressed blank.

[0071] In the present invention, the pressure of the cold isostatic pressing treatment is preferably 180-220 MPa, specifically 180, 200 or 220 MPa, and the time is preferably 180 s.

[0072] After obtaining the compact, the present invention sequentially performs vacuum degassing, vacuum sintering and aging treatment on the compact to obtain the R-Fe-B permanent magnet material.

[0073] In the present invention, the vacuum degree of the vacuum degassing is preferably lower than 9×10 -3 Pa, the vacuum degassing preferably includes a first vacuum degassing, a second vacuum degassing and a third vacuum degassing performed in sequence. The temperature of the first vacuum degassing is preferably 330-360°C, specifically 330, 340, 350 or 360°C, and the holding 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, and the holding 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, and the holding time of the third vacuum degassing is preferably 1-4h, specifically 1, 2, 3 or 4h.

[0074] In the present invention, the vacuum degassing is preferably performed in a vacuum sintering furnace.

[0075] In the present invention, the vacuum degree of the vacuum sintering is preferably lower than 9×10 -3 Pa, the temperature is preferably 1000-1100° C., specifically 1000, 1050, 1085 or 1100° C., and the time is preferably 3-6 h, specifically 3, 4, 5 or 6 h.

[0076] After the vacuum sintering is completed, the present invention preferably stops heating and cools the vacuum sintering furnace by air cooling or argon filling until the temperature in the vacuum sintering furnace is below 100°C.

[0077] In the present invention, the vacuum degree of the aging treatment is preferably less than 9×10 -3 Pa, the aging treatment preferably includes a first aging treatment and a second aging treatment performed sequentially. The temperature of the first aging treatment is preferably 880-910° C., specifically 880, 890, 900 or 910° C., and the holding time of the first aging treatment is preferably 2-4 hours, specifically 2, 3 or 4 hours. The temperature of the second aging treatment is preferably 440-520° C., specifically 440, 450, 460, 480, 500 or 520° C., and the holding time of the second aging treatment is preferably 2-4 hours, specifically 2, 3 or 4 hours.

[0078] After the first aging treatment is completed, the present invention preferably stops heating, cools the steel sheet by air or argon filling to a temperature below 100° C., and then performs the second aging treatment.

[0079] After the second aging treatment is completed, the present invention preferably stops heating and cools the material to a temperature below 80° C. in the vacuum sintering furnace by air cooling or argon filling to obtain the R—Fe—B permanent magnet material.

[0080] The present invention also provides an R-Fe-B permanent magnetic material prepared by the preparation method described in the above technical solution.

[0081] In the present invention, the density of the R-Fe-B permanent magnet material is preferably greater than 7.5 g / cm 3 .

[0082] In the present invention, the intrinsic coercivity of the R-Fe-B permanent magnetic material is preferably Hcj≥20kOe, the remanence Br>14kGs, and the magnetic energy product (BH) max>50MGOe.

[0083] The 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 home appliances, energy-saving elevators, robots and other intelligent equipment as well as smart consumer electronics such as mobile phones.

[0084] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0085] In the present invention, bal means "balance".

[0086] Example 1

[0087] A method for preparing an R-Fe-B permanent magnetic material comprises the following steps:

[0088] 1. The composition of the first main phase R-Fe-BM alloy casting sheet is Nd28FebalCu0.2Co1Ga0.15Zr0.2Nb0.3B1 (wt%). The above raw material composition is melted in a vacuum thin-sheet rapid solidification furnace to prepare an alloy casting sheet with an average thickness of 0.24 mm.

[0089] 2. The composition of the second main phase R-Fe-BM alloy flakes is (Pr0.2Nd0.8)32FebalCu0.2Al0.2Co0.5Ga0.52Ti0.2Nb0.3B0.9 (wt%). The above raw material composition is melted in a vacuum thin-sheet rapid solidification furnace to prepare alloy flakes with an average thickness of 0.26 mm.

[0090] 3. The composition of the grain boundary phase R-Ga-M alloy sheet is Pr60Ga20Cu20 (wt%). The above raw materials are vacuum melted to prepare alloy sheets with an average thickness of 0.26 mm.

[0091] 4. The first main phase R-Fe-BM alloy casting is crushed by a hydrogen crushing process with a dehydrogenation temperature of 580°C to obtain the first main phase R-Fe-BM alloy coarse material.

[0092] 5. The second main phase R-Fe-BM alloy flakes are crushed by hydrogen crushing process with dehydrogenation temperature of 450°C to obtain the second main phase R-Fe-BM alloy coarse material.

[0093] 6. The grain boundary phase R-Ga-M alloy flakes are crushed by hydrogen crushing process with dehydrogenation temperature at 400°C to obtain grain boundary phase R-Ga-M alloy coarse material.

[0094] 7. The first main phase R-Fe-BM alloy coarse material is weighed to weight W1, the second main phase R-Fe-BM alloy coarse material is weighed to weight W2, and the grain boundary phase R-Ga-M alloy coarse material is weighed to weight W3, where W1, W2, and W3 satisfy the following relationship: W1:W2=7.5:2.5, W3=1.2wt%×(W1+W2).

[0095] 8. The weighed first main phase R-Fe-BM alloy coarse material, the second main phase R-Fe-BM alloy coarse material, and the grain boundary phase RM alloy coarse material are mixed, and an antioxidant (the content of the antioxidant in the R-Fe-B permanent magnet material is 0.06wt%) and a lubricant (the content of the lubricant in the R-Fe-B permanent magnet material is 0.05wt%) are added. After the mixture is evenly mixed, it is pulverized by air flow grinding, and the oxygen content is controlled at 10ppm. The average particle size of the obtained powder is 2.8μm. Then, a dispersant (the content of the dispersant in the R-Fe-B permanent magnet material is 0.1wt%) is added to mix the powder evenly.

[0096] 9. Weigh the powder obtained by air flow grinding and place it in a 2.0T oriented magnetic field filled with nitrogen and oxygen-exhausted with an oxygen content of 500 ppm for pressing to obtain a blank. The pressed blank is then subjected to cold isostatic pressing (180 MPa, 180 s) to obtain a compact.

[0097] 10. Place the compact into a vacuum sintering furnace for degassing. -3 Pa, heating was started, and degassing was carried out at three temperature gradients of 330 °C, 580 °C, and 850 °C for 1 h. The vacuum degree at the previous temperature gradient was restored to less than 9 × 10 -3 Pa.

[0098] 11. Continue to heat up and keep it at 1085℃ for 4 hours for vacuum sintering, then stop heating, fill with argon and cool with air. The temperature in the vacuum sintering furnace is lower than 100℃.

[0099] 12. Aging treatment, vacuum degree is less than 9×10 -3 Start heating, keep it at 900℃ for 2h, stop heating, charge with argon and cool it to below 100℃, then continue heating to 480℃ and keep it for 3h, stop heating, charge with argon and cool it to below 80℃, then open the furnace door to discharge the material.

[0100] 13. The magnetic properties of the R-Fe-B permanent magnet material were measured at room temperature. The remanence Br was 14.40 kGs, the intrinsic coercivity Hcj was 20.10 kOe, and the magnetic energy product (BH) max was 50.20 MGOe. The density of the R-Fe-B permanent magnet material was 7.56 g / cm 3 .

[0101] Comparative Example 1

[0102] A method for preparing an R-Fe-B permanent magnetic material comprises the following steps:

[0103] 1. The composition of the first main phase R-Fe-BM alloy casting sheet is Nd28FebalCu0.2Co1Ga0.15Zr0.2Nb0.3B1 (wt%). The above raw material composition is melted in a vacuum thin-sheet rapid solidification furnace to prepare an alloy casting sheet with an average thickness of 0.24 mm.

[0104] 2. The composition of the second main phase R-Fe-BM alloy flakes is (Pr0.2Nd0.8)32FebalCu0.2Al0.2Co0.5Ga0.52Ti0.2Nb0.3B0.9 (wt%). The above raw material composition is melted in a vacuum thin-sheet rapid solidification furnace to prepare alloy flakes with an average thickness of 0.26 mm.

[0105] 3. The first main phase R-Fe-BM alloy flakes are crushed by hydrogen crushing process with dehydrogenation temperature of 580°C to obtain the first main phase R-Fe-BM alloy coarse material.

[0106] 4. The second main phase R-Fe-BM alloy flakes are crushed by hydrogen crushing process with dehydrogenation temperature of 450°C to obtain the second main phase R-Fe-BM alloy coarse material.

[0107] 5. The first main phase R-Fe-BM alloy coarse material is weighed to a weight of W1, and the second main phase R-Fe-BM alloy coarse material is weighed to a weight of W2, wherein W1 and W2 satisfy the following relationship: W1:W2=7.5:2.5.

[0108] 6. The weighed first main phase R-Fe-BM alloy coarse material and the second main phase R-Fe-BM alloy coarse material are mixed, and antioxidant (the content of antioxidant in R-Fe-B permanent magnet material is 0.06wt%) and lubricant (the content of lubricant in R-Fe-B permanent magnet material is 0.05wt%) are added. After the mixture is uniform, it is pulverized by air flow milling. The oxygen content is controlled at 10ppm. The average particle size of the obtained powder is 2.8μm. Dispersant (the content of dispersant in R-Fe-B permanent magnet material is 0.1wt%) is added to mix the powder. The mixed powder is uniform.

[0109] 7. Weigh the powder obtained by air flow grinding and place it in a 2.0T oriented magnetic field filled with nitrogen and oxygen-exhausted with an oxygen content of 500 ppm for pressing to obtain a blank. The pressed blank is then subjected to cold isostatic pressing (180 MPa, 180 s) to obtain a compact.

[0110] 8. Place the compact into a vacuum sintering furnace for degassing. Wait until the vacuum degree is lower than 9×10 -3 Pa, heating was started, and degassing was carried out at three temperature gradients of 330 °C, 580 °C, and 850 °C for 1 h. The vacuum degree at the previous temperature gradient was restored to less than 9 × 10 -3 Pa.

[0111] 9. Continue to heat up and keep it at 1085℃ for 4 hours for vacuum sintering, then stop heating, fill with argon and cool with air. The temperature in the vacuum sintering furnace is lower than 100℃.

[0112] 10. Aging treatment, vacuum degree is less than 9×10 -3 Start heating, keep it at 900℃ for 2h, stop heating, charge with argon and cool it to below 100℃, then continue heating to 480℃ and keep it for 3h, stop heating, charge with argon and cool it to below 80℃, then open the furnace door to discharge the material.

[0113] 11. The magnetic properties of R-Fe-B permanent magnet material were measured at room temperature. The remanence Br was 14.53 kGs, the intrinsic coercivity Hcj was 15.10 kOe, and the magnetic energy product (BH) max was 51.20 MGOe. The density of the R-Fe-B permanent magnet material was 7.56 g / cm 3 .

[0114] Example 2

[0115] A method for preparing an R-Fe-B permanent magnetic material comprises the following steps:

[0116] 1. The composition of the first main phase R-Fe-BM alloy casting is (Pr0.25Nd0.75)29.5FebalCu0.2Co1.2Ga0.1Zr0.15Nb0.2B0.98 (wt%). The above raw materials are melted in a vacuum thin-sheet rapid solidification furnace to prepare alloy castings with an average thickness of 0.26 mm.

[0117] 2. The composition of the second main phase R-Fe-BM alloy sheet is (Pr0.25Nd0.75)35FebalCu0.2Al0.2Co0.5Ga0.50Ti0.15Nb0.25B0.8 (wt%). The above raw material composition is melted in a vacuum thin sheet rapid solidification furnace to prepare an alloy sheet with an average thickness of 0.26 mm.

[0118] 3. The composition of the grain boundary phase R-Ga-M alloy sheet is Pr60Ga20Cu15Al5 (wt%). The above raw materials are vacuum melted to prepare alloy sheets with an average thickness of 0.2 mm.

[0119] 4. The first main phase R-Fe-BM alloy casting sheet is crushed by a hydrogen crushing process with a dehydrogenation temperature of 540°C to obtain the first main phase R-Fe-BM alloy coarse material.

[0120] 5. The second main phase R-Fe-BM alloy flakes are crushed by hydrogen crushing process with dehydrogenation temperature of 480°C to obtain the second main phase R-Fe-BM alloy coarse material.

[0121] 6. The grain boundary phase R-Ga-M alloy flakes are crushed by hydrogen crushing process with dehydrogenation temperature at 440℃ to obtain grain boundary phase R-Ga-M alloy coarse material.

[0122] 7. The first main phase R-Fe-BM alloy coarse material is weighed to weight W1, the second main phase R-Fe-BM alloy coarse material is weighed to weight W2, and the grain boundary phase R-Ga-M alloy coarse material is weighed to weight W3, where W1, W2, and W3 satisfy the following relationship: W1:W2=7:3, W3=1.2wt%×(W1+W2).

[0123] 8. The weighed first main phase R-Fe-BM alloy coarse material, the second main phase R-Fe-BM alloy coarse material, and the grain boundary phase RM alloy coarse material are mixed, and the antioxidant content in the R-Fe-B permanent magnet material is 0.06wt%) and lubricant (the lubricant content in the R-Fe-B permanent magnet material is 0.05wt%) are added. After the mixing is uniform, the powder is pulverized by air flow grinding, and the oxygen content is controlled at 10ppm. The average particle size of the obtained powder is 2.8μm. Then, a dispersant (the dispersant content in the R-Fe-B permanent magnet material is 0.1wt%) is added to mix the powder uniformly.

[0124] 9. Weigh the powder obtained by air flow grinding and place it in a 2.0T oriented magnetic field filled with nitrogen and oxygen-exhausted with an oxygen content of 500 ppm for pressing to obtain a blank. The pressed blank is then subjected to cold isostatic pressing (180 MPa, 180 s) to obtain a compact.

[0125] 10. Place the compact into a vacuum sintering furnace for degassing. -3 Pa, heating was started, and degassing was carried out at three temperature gradients of 330 °C, 580 °C, and 850 °C for 1 h. The vacuum degree at the previous temperature gradient was restored to less than 9 × 10 -3 Pa.

[0126] 11. Continue to heat up and keep it at 1085℃ for 4 hours for vacuum sintering, then stop heating, fill with argon and cool with air. The temperature in the vacuum sintering furnace is lower than 100℃.

[0127] 12. Aging treatment, vacuum degree is less than 9×10 -3Start heating, keep warm at 900℃ for 2h, stop heating, charge with argon and cool until the temperature is below 100℃, then continue heating to 440℃ and keep warm for 3h, stop heating, charge with argon and cool until the temperature in the vacuum sintering furnace is below 80℃, and open the furnace door to discharge the material.

[0128] 13. The magnetic properties of the R-Fe-B permanent magnet material were measured at room temperature. The remanence Br was 14.30 kGs, the intrinsic coercivity Hcj was 20.25 kOe, and the magnetic energy product (BH) max was 50.50 MGOe. The density of the R-Fe-B permanent magnet material was 7.58 g / cm 3 .

[0129] Example 3

[0130] A method for preparing an R-Fe-B permanent magnetic material comprises the following steps:

[0131] 1. The composition of the first main phase R-Fe-BM alloy casting sheet is (Pr0.2Nd0.8)29FebalCu0.2Co1Ga0.15Zr0.25Nb0.1B0.96 (wt%). The above raw material composition is melted in a vacuum thin-sheet rapid solidification furnace to prepare an alloy casting sheet with an average thickness of 0.20 mm.

[0132] 2. The composition of the second main phase R-Fe-BM alloy sheet is (Pr0.2Nd0.8)32FebalCu0.2Al0.2Co0.5Ga0.50Ti0.15Nb0.25B0.9 (wt%). The above raw material composition is melted in a vacuum thin-sheet rapid solidification furnace to prepare an alloy sheet with an average thickness of 0.20 mm.

[0133] 3. The composition of the grain boundary phase R-Ga-M alloy sheet is (Pr0.2Nd0.8)70Ga20Cu5Al5 (wt%). The above raw materials are vacuum melted to prepare alloy sheets with an average thickness of 0.18 mm.

[0134] 4. The first main phase R-Fe-BM alloy casting is crushed by a hydrogen crushing process with a dehydrogenation temperature of 560°C to obtain the first main phase R-Fe-BM alloy coarse material.

[0135] 5. The second main phase R-Fe-BM alloy flakes are crushed by hydrogen crushing process with dehydrogenation temperature of 440°C to obtain the second main phase R-Fe-BM alloy coarse material.

[0136] 6. The grain boundary phase R-Ga-M alloy flakes are crushed by hydrogen crushing process with dehydrogenation temperature at 400°C to obtain grain boundary phase R-Ga-M alloy coarse material.

[0137] 7. The first main phase R-Fe-BM alloy coarse material is weighed to weight W1, the second main phase R-Fe-BM alloy coarse material is weighed to weight W2, and the grain boundary phase R-Ga-M alloy coarse material is weighed to weight W3, where W1, W2, and W3 satisfy the following relationship: W1:W2=7.5:2.5, W3=2wt%×(W1+W2).

[0138] 8. The weighed first main phase R-Fe-BM alloy coarse material, the second main phase R-Fe-BM alloy coarse material, and the grain boundary phase RM alloy coarse material are mixed, and an antioxidant (the content of the antioxidant in the R-Fe-B permanent magnet material is 0.06wt%) and a lubricant (the content of the lubricant in the R-Fe-B permanent magnet material is 0.05wt%) are added. After the mixture is evenly mixed, it is pulverized by air flow grinding, and the oxygen content is controlled at 10ppm. The average particle size of the obtained powder is 2.8μm. Then, a dispersant (the content of the dispersant in the R-Fe-B permanent magnet material is 0.1wt%) is added to mix the powder evenly.

[0139] 9. Weigh the powder obtained by air flow grinding and place it in a 2.5T oriented magnetic field filled with nitrogen and oxygen-exhausted with an oxygen content of 100 ppm for pressing to obtain a blank. The pressed blank is then subjected to cold isostatic pressing (180 MPa, 180 s) to obtain a compact.

[0140] 10. Place the compact into a vacuum sintering furnace for degassing. -3 Pa, heating was started, and degassing was carried out at three temperature gradients of 330 °C, 580 °C, and 850 °C for 1 h. The vacuum degree at the previous temperature gradient was restored to less than 9 × 10 -3 Pa.

[0141] 11. Continue to heat up and keep it at 1085℃ for 4 hours for vacuum sintering, then stop heating, fill with argon and cool with air. The temperature in the vacuum sintering furnace is lower than 100℃.

[0142] 12. Aging treatment, vacuum degree is less than 9×10 -3 Start heating, keep warm at 900℃ for 2h, stop heating, charge with argon and cool until the temperature is below 100℃, then continue heating to 460℃ and keep warm for 3h, stop heating, charge with argon and cool until the temperature in the vacuum sintering furnace is below 80℃, and open the furnace door to discharge the material.

[0143] 13. The magnetic properties of R-Fe-B permanent magnet material were measured at room temperature. The remanence Br was 14.45 kGs, the intrinsic coercive force Hcj was 20.62 kOe, and the magnetic energy product (BH) max was 51.20 MGOe.

[0144] The density of the prepared R-Fe-B permanent magnet material is 7.58 g / cm 3.

[0145] Example 4

[0146] A method for preparing an R-Fe-B permanent magnetic material comprises the following steps:

[0147] 1. The composition of the first main phase R-Fe-BM alloy flake is (Pr0.2Nd0.8)28Ce1.5FebalCu0.1Co1Ga0.15Zr0.25Nb0.15B1 (wt%). The above raw materials are melted in a vacuum sheet rapid solidification furnace to prepare alloy flakes with an average thickness of 0.28 mm.

[0148] 2. The composition of the second main phase R-Fe-BM alloy sheet is (Pr0.2Nd0.8)32FebalCu0.2Al0.2Co0.5Ga0.50Ti0.15Nb0.25B0.9 (wt%). The above raw material composition is melted in a vacuum thin-sheet rapid solidification furnace to prepare an alloy sheet with an average thickness of 0.24 mm.

[0149] 3. The composition of the grain boundary phase R-Ga-M alloy sheet is (Pr0.2Nd0.8)70Ga20Cu5Al5 (wt%). The above raw materials are vacuum melted to prepare alloy sheets with an average thickness of 0.20 mm.

[0150] 4. The first main phase R-Fe-BM alloy casting is crushed by a hydrogen crushing process with a dehydrogenation temperature of 560°C to obtain the first main phase R-Fe-BM alloy coarse material.

[0151] 5. The second main phase R-Fe-BM alloy flakes are crushed by hydrogen crushing process with dehydrogenation temperature of 440°C to obtain the second main phase R-Fe-BM alloy coarse material.

[0152] 6. The grain boundary phase R-Ga-M alloy flakes are crushed by hydrogen crushing process with dehydrogenation temperature at 440℃ to obtain grain boundary phase R-Ga-M alloy coarse material.

[0153] 7. The first main phase R-Fe-BM alloy coarse material is weighed to weight W1, the second main phase R-Fe-BM alloy coarse material is weighed to weight W2, and the grain boundary phase R-Ga-M alloy coarse material is weighed to weight W3, where W1, W2, and W3 satisfy the following relationship: W1:W2=7.5:2.5, W3=1.8wt%×(W1+W2).

[0154] 8. The weighed first main phase R-Fe-BM alloy coarse material, the second main phase R-Fe-BM alloy coarse material, and the grain boundary phase RM alloy coarse material are mixed, and an antioxidant (the content of the antioxidant in the R-Fe-B permanent magnet material is 0.06wt%) and a lubricant (the content of the lubricant in the R-Fe-B permanent magnet material is 0.05wt%) are added. After the mixture is evenly mixed, it is pulverized by air flow grinding, and the oxygen content is controlled at 10ppm. The average particle size of the obtained powder is 2.8μm. Then, a dispersant (the content of the dispersant in the R-Fe-B permanent magnet material is 0.1wt%) is added to mix the powder evenly.

[0155] 9. Weigh the powder obtained by air flow grinding and place it in a 2.5T oriented magnetic field filled with nitrogen and oxygen-exhausted with an oxygen content of 100 ppm for pressing to obtain a blank. The pressed blank is then subjected to cold isostatic pressing (180 MPa, 180 s) to obtain a compact.

[0156] 10. Place the compact into a vacuum sintering furnace for degassing. -3 Pa, heating was started, and degassing was carried out at three temperature gradients of 330 °C, 580 °C, and 850 °C for 1 h. The vacuum degree at the previous temperature gradient was restored to less than 9 × 10 -3 Pa.

[0157] 11. Continue to heat up and keep it at 1085℃ for 4 hours for vacuum sintering, then stop heating, fill with argon and cool with air. The temperature in the vacuum sintering furnace is lower than 100℃.

[0158] 12. Aging treatment, vacuum degree is less than 9×10 -3 Start heating, keep it at 900℃ for 2h, stop heating, charge with argon and cool it to below 100℃, then continue heating to 450℃ and keep it for 3h, stop heating, charge with argon and cool it to below 80℃, then open the furnace door to discharge the material.

[0159] 13. The magnetic properties of the R-Fe-B permanent magnet material were measured at room temperature. The remanence Br was 14.20 kGs, the intrinsic coercivity Hcj was 20.15 kOe, and the magnetic energy product (BH) max was 50.18 MGOe. The density of the R-Fe-B permanent magnet material was 7.56 g / cm 3 .

[0160] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation thereto. It should be noted that those skilled in the art may make various improvements and modifications without departing from the principles of the present invention, and such improvements and modifications shall also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing an R-Fe-B permanent magnetic material, characterized in that: The R-Fe-B permanent magnet material does not contain heavy rare earth elements Dy and Tb, and comprises the following steps: The first main phase R-Fe-BM alloy is subjected to a first hydrogen cracking and a first dehydrogenation in sequence to obtain a first main phase R-Fe-BM alloy coarse material; in the first main phase R-Fe-BM 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 second main phase R-Fe-BM alloy is subjected to a second hydrogen cracking and a second dehydrogenation in sequence to obtain a second main phase R-Fe-BM alloy coarse material; in the second main phase R-Fe-BM 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 grain boundary phase R-Ga-M alloy is subjected to a third hydrogen cracking and a third dehydrogenation in sequence to obtain a grain boundary phase R-Ga-M alloy coarse 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 Cu, Al, Ge, Zn, Sn, Ag and Si, and the content of R in the grain boundary phase R-Ga-M alloy is 60wt%-90wt%, the content of Ga is 10wt%-20wt%, and the content of M is 0wt%-30wt% and is not 0wt%; The first main phase R-Fe-BM alloy coarse material, the second main phase R-Fe-BM alloy coarse material, the grain boundary phase R-Ga-M alloy coarse material, an antioxidant, a lubricant and a dispersant are mixed, and then pressed under a magnetic field to obtain a blank; The blank is subjected to cold isostatic pressing to obtain a compact; The green compact is subjected to vacuum degassing, vacuum sintering and aging treatment in sequence to obtain the R-Fe-B permanent magnet material; During the mixing, the mass W1 of the first main phase R-Fe-BM alloy coarse material, the mass W2 of the second main phase R-Fe-BM alloy coarse material, and the mass W3 of the grain boundary phase R-Ga-M alloy coarse material satisfy the relationship: W1:W2=7.5:2.5; W3=(1.2%~2%)×(W1+W2); The content of R in the first main phase R-Fe-BM alloy is 28wt%-31wt%, the content of B element is 0.93wt%-1.03wt%, the content of M element is 1wt%-2wt%, and the balance is Fe element and inevitable impurities; when M in the first main phase R-Fe-BM 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 first main phase R-Fe-BM alloy are independently 0wt%-0.25wt% and not 0wt%; The content of R in the second main phase R-Fe-BM alloy is 30wt%~36.5wt%, the content of B element is 0.8wt%~0.95wt%, the content of M element is 1wt%~3wt%, and the balance is Fe element and inevitable impurities; when M in the second main phase R-Fe-BM 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 first main phase R-Fe-BM alloy are independently 0.25wt%~0.56wt%.

2. The preparation method according to claim 1, characterized in that The temperature of the first dehydrogenation is 500-580°C; the temperature of the second dehydrogenation is 320-520°C; and the temperature of the third dehydrogenation is 320-520°C.

3. The preparation method according to claim 1, characterized in that The vacuum degree of the vacuum degassing is lower than 9×10 - 3 Pa, the vacuum degassing includes a first vacuum degassing, a second vacuum degassing and a third vacuum degassing performed in sequence, the temperature of the first vacuum degassing is 330~360℃, the insulation time of the first vacuum degassing is 1~4h, the temperature of the second vacuum degassing is 550~580℃, the insulation time of the second vacuum degassing is 1~4h, the temperature of the third vacuum degassing is 850~880℃, and the insulation time of the third vacuum degassing is 1~4h.

4. The preparation method according to claim 1, characterized in that The vacuum degree of the vacuum sintering is lower than 9×10 - 3 Pa, temperature is 1000~1100℃, and time is 3~6h.

5. The preparation method according to claim 1, characterized in that The vacuum degree of the aging treatment is less than 9×10 - 3 Pa, the aging treatment includes a first aging treatment and a second aging treatment performed sequentially, the temperature of the first aging treatment is 880-910°C, the holding time of the first aging treatment is 2-4 hours, the temperature of the second aging treatment is 440-520°C, and the holding time of the second aging treatment is 2-4 hours.

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

7. The R-Fe-B permanent magnet material obtained by the preparation method according to any one of claims 1 to 6.