NdFeB permanent magnet material and preparation method thereof

Abstract

The present invention discloses a NdFeB permanent magnet material and a preparation method thereof. The preparation of the NdFeB permanent magnet material comprises the following steps: respectively providing NdFeB magnetic powder and cobalt metal powder; mixing the NdFeB magnetic powder and cobalt metal powder to form mixed magnetic powder; sequentially performing orientation molding, hot pressing sintering, sintering and tempering treatment on the mixed magnetic powder to obtain the NdFeB permanent magnet material. The preparation method can effectively improve the temperature stability of the remanence and coercive force of the permanent magnet material; and can make the Co element concentrate in the main phase epitaxial layer without entering the main phase, thereby effectively reducing the amount of metal Co while ensuring the improvement of the high temperature stability of the rare earth permanent magnet, and the production cost is low, simple and easy, easy to operate and industrialize.

Description

Technical Field

[0001] The invention belongs to the technical field of rare earth permanent magnet materials, and particularly relates to a method for preparing a neodymium iron boron permanent magnet material with high temperature stability, and also relates to the neodymium iron boron permanent magnet material prepared by the preparation method. Background Art

[0002] Rare earth permanent magnets are permanent magnetic materials based on intermetallic compounds formed by rare earth metal elements and transition metals. Neodymium iron boron permanent magnets (also known as NdFeB permanent magnets) are the permanent magnetic materials with the highest magnetic properties at present. They are widely used in high-tech fields such as aerospace, computers, oil extraction, transportation, machinery, new energy, communications, and national defense.

[0003] In order to further meet the actual needs in the fields of electric vehicles, wind power generation, etc., permanent magnet materials must have high coercivity to ensure the stability of magnets at high temperatures. At present, the industry mainly increases the coercivity of magnets by adding heavy rare earth elements such as Dy and Tb; however, the addition of excessive heavy rare earths will greatly reduce the remanence of permanent magnet materials, and because heavy rare earths are expensive, the production cost of permanent magnet materials is also greatly increased. Summary of the invention

[0004] In view of this, it is necessary for the present invention to provide a method for preparing a NdFeB permanent magnet material. The NdFeB permanent magnet material prepared by the preparation method has excellent high-temperature stability.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] The present invention provides a method for preparing a NdFeB permanent magnet material, comprising the following steps:

[0007] Provide NdFeB magnetic powder and cobalt metal powder respectively;

[0008] Mixing the NdFeB magnetic powder and cobalt metal powder to form mixed magnetic powder;

[0009] The mixed magnetic powder is sequentially subjected to orientation molding, hot pressing sintering, sintering and tempering treatment to obtain a NdFeB permanent magnet material.

[0010] In a further embodiment, the composition of the NdFeB magnetic powder is (Nd, Pr) by mass percentage. x Fe (100-x-y-z) B y M z , wherein 29%≤x≤33%, 0.80%≤y≤1.0%, 0<z≤4%; and M is at least one of Al, Cu, and Ga.

[0011] In a further embodiment, the NdFeB magnetic powder is jet milled NdFeB magnetic powder, which is obtained by jet milling process;

[0012] Preferably, the particle size of the NdFeB magnetic powder is between 2 μm and 10 μm.

[0013] In a further embodiment, the cobalt metal powder is at least one of cobalt powder and cobalt alloy powder;

[0014] Preferably, the cobalt alloy powder is selected from at least one of CoFe alloy powder, CoAl alloy powder and CoCu alloy powder;

[0015] Preferably, the cobalt metal powder is prepared by an atomization or evaporation condensation process, and has a particle size D50≤30 μm.

[0016] In a further embodiment, in the mixed magnetic powder, the NdFeB magnetic powder accounts for 90%-99.5% by mass, and the cobalt metal powder accounts for 0.5%-10% by mass.

[0017] In a further embodiment, the oriented molding process is specifically as follows: the mixed magnetic powder is oriented and pressed at a magnetic field strength of 2.3T-2.5T, and then isostatically pressed at 150-200MPa.

[0018] In a further embodiment, the hot pressing sintering process is as follows: at a pressure of 20 MPa-400 MPa and a vacuum degree of less than 10 -1 , sintering for 5-10 minutes at a temperature of 800℃-1100℃.

[0019] In a further embodiment, the sintering process is as follows: sintering at a temperature of 1000-1100° C. for 0.5-10 h in a vacuum or protective atmosphere; the protective atmosphere is a rare gas or nitrogen.

[0020] In a further embodiment, the tempering process is as follows: a two-stage tempering treatment is performed in a vacuum or protective atmosphere, wherein the temperature of the first-stage tempering treatment is 850-900°C, and the treatment time is 2-3h; the temperature of the second-stage tempering treatment is 480-550°C, and the treatment time is 2-3h.

[0021] The present invention further provides a NdFeB permanent magnet material, which is prepared by the preparation method as described above.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The present invention densifies the powder by mixing the jet milled powder and the Co powder or its alloy through a low temperature hot pressing sintering process. The low temperature hot pressing sintering process can effectively inhibit the diffusion of the Co element along the main phase grains, so that the Co atoms in the main phase Nd2Fe 14 B grain epitaxial layer forms Nd2(FeCo) 14B shell layer, which can increase the Curie temperature of the NdFeB main phase, thereby significantly reducing the temperature coefficient of remanence and the temperature coefficient of coercivity, and improving the temperature stability of the remanence and coercivity of the rare earth permanent magnet; and the method of the present invention can make the Co element concentrate in the epitaxial layer of the main phase without entering the interior of the main phase, thereby effectively reducing the amount of metal Co while ensuring the improvement of the high-temperature stability of the rare earth permanent magnet.

[0024] In summary, the implementation of the method of the present invention can effectively reduce the use of heavy rare earths and reduce production costs; it can also effectively reduce the use of strategic metal Co, and can solve the problem of reduced remanence caused by adding heavy rare earths to increase coercivity.

[0025] In addition, the preparation method of the present invention has the advantages of being clean and pollution-free, having low production cost, being simple and easy to operate, and being easy to industrialize. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of the principle of improving the high temperature stability of the NdFeB permanent magnet material of the present invention. DETAILED DESCRIPTION

[0027] Embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0029] The first aspect of the present invention discloses a method for preparing a NdFeB permanent magnet material, which mainly comprises the following steps:

[0030] Provide NdFeB magnetic powder and cobalt metal powder respectively

[0031] The NdFeB magnetic powder described in this article is a conventional permanent magnetic material in the art, and its specific composition can be adjusted according to actual conditions. According to some specific embodiments of the present invention, the composition of the NdFeB magnetic powder is (Nd, Pr) by mass percentage: x Fe (100-x-y-z) B y M z, wherein 29%≤x≤33%, 0.80%≤y≤1.0%, 0<z≤4%; M is at least one of Al, Cu, and Ga. Further, the particle size of the NdFeB magnetic powder in this article is between 2μm-10μm, and its specific preparation can adopt the conventional powder making process in the art. In some specific embodiments of the present invention, the NdFeB magnetic powder in this article is prepared by air flow milling process, and its main steps include rapid solidification, hydrogen rupture and air flow milling. The specific process can be: mixing the ingredients according to the proportion of each element in the NdFeB magnetic powder; mixing the prepared raw materials and melting and rapid solidification in an inert atmosphere (rare gas or nitrogen) to obtain NdFeB alloy sheets; crushing the NdFeB alloy sheets by hydrogen rupture and air flow milling to obtain NdFeB magnetic powder of the required particle size.

[0032] The cobalt metal powder described herein refers to a metal powder containing cobalt element, which may be a cobalt powder containing only cobalt element, or an alloy powder containing cobalt element. In some specific embodiments of the present invention, specific examples of cobalt alloy powder include but are not limited to at least one of CoFe alloy powder, CoAl alloy powder, and CoCu alloy powder. Preferably, the mass content of Co in the cobalt alloy powder is between 20% and 90%. Further, the particle size of the cobalt metal powder is ≤30μm, preferably, the particle size of the cobalt metal powder is between 1μm and 15μm. Its specific preparation, according to an embodiment of the present invention, can be carried out by the following method: the ingredients are prepared according to the composition of the cobalt metal powder, the prepared raw materials are mixed and then smelted in an inert atmosphere (rare gas or nitrogen) to obtain a master alloy; the master alloy is made into cobalt metal powder by vacuum atomization or evaporation condensation process. Among them, the specific parameters of the vacuum atomization or evaporation condensation process can be adjusted according to the actual situation, as long as the cobalt metal powder of the required particle size is obtained, so it will not be elaborated here.

[0033] Forming mixed magnetic powder

[0034] The NdFeB magnetic powder and the cobalt metal powder are fully mixed to form a mixed magnetic powder. There is no particular limitation on the mixing method, and the conventional mechanical mixing method in the art can be used. According to an embodiment of the present invention, the above two powders are added to a mixer in a certain proportion and mixed for 1h-3h to obtain a mixed magnetic powder. Furthermore, in terms of mass percentage, in the mixed magnetic powder, the mass percentage of the NdFeB magnetic powder is 90%-99.5%, and the mass percentage of the cobalt metal powder is 0.5%-10%. Figure 1 As shown in the figure, due to the ability to form Nd2(CoFe) 14 The shell structure of B can concentrate the Co element in the epitaxial layer of the main phase instead of entering the interior of the main phase, so that the amount of Co element can be greatly reduced. Therefore, more preferably, when the mass percentage of cobalt metal powder in the mixed magnetic powder is 0.5%-3%, the high-temperature stability of remanence and coercive force can be significantly improved.

[0035] Forming Green Magnets

[0036] Specifically, the mixed magnetic powder is oriented and formed to obtain a green magnet. The preparation of the green magnet can adopt a conventional magnetic field orientation forming process in the art, and the specific parameters can be adjusted according to actual conditions. In some specific embodiments of the present invention, specifically: the mixed magnetic powder is oriented and formed under a magnetic field strength of 2.3-2.5T, and then isostatically pressed at 150MPa-200MPa to form a green magnet.

[0037] Forming a preform

[0038] Specifically, the green magnet is hot pressed and sintered to form a preform. The low temperature hot pressing and sintering process can effectively inhibit the diffusion of Co elements along the main phase grains, so that Co atoms are in the main phase Nd2Fe 14 B grain epitaxial layer forms Nd2(FeCo) 14 B shell layer, which can increase the Curie temperature of the NdFeB main phase, thereby significantly reducing the temperature coefficient of remanence and the temperature coefficient of coercivity, and improving the temperature stability of the remanence and coercivity of the rare earth permanent magnet. This method can concentrate the Co element in the epitaxial layer of the main phase without entering the interior of the main phase, thereby effectively reducing the amount of metal Co while ensuring the improvement of the high-temperature stability of the rare earth permanent magnet. According to an embodiment of the present invention, the hot pressing sintering process is specifically as follows: placing the green magnet in a vacuum hot pressing sintering furnace at a pressure of 20MPa-400MPa and a vacuum degree of less than 10 -1 , sintering temperature is 800℃-1100℃ for 5-10min.

[0039] Prepared NdFeB permanent magnet material

[0040] The preform is then subjected to sintering and tempering treatments in sequence to obtain NdFeB permanent magnet materials. It can be understood that the sintering and tempering treatments here are conventional processes in this field. The purpose of high-temperature sintering is to eliminate surface defects of the grains to obtain relatively rounded main phase grains, and the purpose of aging and tempering treatment is to obtain a continuously distributed Nd-rich phase to improve the coercive force of the magnet. The specific parameter conditions can be adjusted according to actual conditions. According to an embodiment of the present invention, the sintering in the preparation method is specifically carried out in a vacuum environment or a protective atmosphere, with a sintering temperature of 1000°C-1100°C and a sintering time of 0.5h-10h. The tempering treatment is also carried out in a vacuum environment or a protective atmosphere. Preferably, the tempering treatment is a two-stage tempering treatment, wherein the temperature of the first-stage tempering is 850°C-900°C, the time of the first-stage tempering is 2h-3h, the temperature of the second-stage tempering is 480°C-550°C, and the time of the second-stage tempering is 2h-3h. It is understandable that the protective atmosphere described in the preparation method refers to an atmosphere filled with a rare gas or nitrogen, which will not be elaborated here.

[0041] The second aspect of the present invention discloses a NdFeB permanent magnet material, which is prepared by the preparation method described in the first aspect of the present invention and has beneficial high-temperature stability.

[0042] The present invention is described below by means of specific examples. It should be noted that the following specific examples are only for illustrative purposes and do not limit the scope of the present invention in any way. In addition, unless otherwise specified, methods without specific conditions or steps are conventional methods, and the reagents and materials used can be obtained from commercial channels.

[0043] Example 1

[0044] In this embodiment, the chemical formula of NdFeB magnetic powder is (NdPr) 30.5 oeLh 0.15 Al 0.1 Fe bal. B 0.94 , the cobalt metal powder uses pure Co powder.

[0045] The preparation of NdFeB permanent magnet materials is as follows:

[0046] The raw materials with purity greater than 99% are classified into (NdPr) 30.5 oeLh 0.15 Al 0.1 Fe bal. B 0.94 The alloy sheet with a thickness of 0.3 mm is prepared by using a quick-setting process; the alloy sheet is subjected to hydrogen crushing and air flow grinding to obtain NdFeB magnetic powder with an average particle size of 2 μm-3 μm;

[0047] Pure Co powder is passed through a vacuum gas atomization powder making system to obtain a powder with an average particle size of 4μm-5μm;

[0048] The two powders are mixed in a mixer for 3 hours to obtain mixed magnetic powder, wherein the mass percentage of NdFeB magnetic powder is 98% and the mass percentage of metal Co powder is 2%;

[0049] The mixed magnetic powder is pressed into shape under an orientation field of 2.3 T, and then cold isostatically pressed under a pressure of 150 MPa to obtain a green magnet;

[0050] The green magnet was placed in a vacuum hot pressing sintering furnace and sintered at 850°C for 5 minutes under a pressure of 200MPa; then sintered at 1050°C for 3 hours in a vacuum sintering furnace and cooled; finally, the primary tempering was carried out at 900°C for 2 hours and the secondary tempering was carried out at 510°C for 2 hours. After completion, it was gas quenched and air-cooled, cooled to room temperature and then taken out of the furnace to obtain NdFeB permanent magnet material.

[0051] Comparative Example 1

[0052] In this comparative example, the chemical formula of NdFeB is (NdPr) 30.5 oeLh 0.15 Al 0.1 Fe bal. B 0.94 The alloy sheet with a thickness of 0.3 mm was prepared by the quick-setting process, and the alloy sheet was subjected to hydrogen crushing and air flow milling to prepare NdFeB magnetic powder with an average particle size of 2 μm-3 μm;

[0053] The NdFeB magnetic powder is pressed into shape under an orientation field of 2.3T, and then cold isostatically pressed under a pressure of 150MPa to obtain a green magnet.

[0054] The green magnet was placed in a vacuum hot pressing sintering furnace and sintered at 850°C for 5 minutes under a pressure of 200MPa; then sintered at 1050°C for 3 hours in a vacuum sintering furnace and cooled; finally, the primary tempering was carried out at 900°C for 2 hours and the secondary tempering was carried out at 510°C for 2 hours. After completion, it was gas quenched and air-cooled, cooled to room temperature and then taken out of the furnace to obtain NdFeB permanent magnet material.

[0055] Comparative Example 2

[0056] In this comparative example, the chemical formula of NdFeB magnetic powder is (NdPr) 30.5 oeLh 0.15 Al 0.1 Fe bal. B 0.94 , the cobalt metal powder uses pure Co powder.

[0057] The preparation of NdFeB permanent magnet materials is as follows:

[0058] The raw materials with purity greater than 99% are classified into (NdPr) 30.5 oeLh 0.15 Al 0.1 Fe bal. B 0.94 The alloy sheet with a thickness of 0.3 mm is prepared by using a quick-setting process; the alloy sheet is subjected to hydrogen crushing and air flow grinding to obtain NdFeB magnetic powder with an average particle size of 2 μm-3 μm;

[0059] Pure Co powder is passed through a vacuum gas atomization powder making system to obtain a powder with an average particle size of 4μm-5μm;

[0060] The two powders are mixed in a mixer for 3 hours to obtain mixed magnetic powder, wherein the mass percentage of NdFeB magnetic powder is 98% and the mass percentage of metal Co powder is 2%;

[0061] The mixed magnetic powder is pressed into shape under an orientation field of 2.3 T, and then cold isostatically pressed under a pressure of 150 MPa to obtain a green magnet;

[0062] The green magnet is sintered at 1050°C in a vacuum sintering furnace for 3 hours and cooled; finally, it is subjected to primary tempering at 900°C for 2 hours and secondary tempering at 510°C for 2 hours. After completion, it is gas quenched and air-cooled, and then taken out of the furnace after cooling to room temperature to obtain NdFeB permanent magnet material.

[0063] Test Example 1

[0064] The NdFeB permanent magnet materials obtained in Example 1 and Comparative Examples 1-2 were processed into magnets of the same specifications and relevant performance tests were performed. The results are shown in Table 1.

[0065] Table 1 NdFeB permanent magnet material performance test results

[0066]

[0067] Note: The remanence and coercive force tests in Table 1 refer to those described in GB-T 3217-2013 Magnetic Test Methods for Permanent Magnet (Hard Magnetic) Materials;

[0068] Magnetic flux attenuation rate (%) = (magnetic flux before aging - magnetic flux after aging) / magnetic flux before aging × 100%

[0069] Example 2

[0070] In this embodiment, the chemical formula of NdFeB magnetic powder is (NdPr) 29.5 oeLh 0.2 Al 0.5 Zr 0.2 Fe bal. B 0.96The cobalt metal powder is CoFe (Co content is 60%) alloy powder.

[0071] The preparation of NdFeB permanent magnet materials is as follows:

[0072] The raw materials with purity greater than 99% are classified into (NdPr) 29.5 oeLh 0.2 Al 0.5 Zr 0.2 Fe bal. B 0.96 The alloy sheet with a thickness of 0.3 mm is prepared by using the quick-setting process; the alloy sheet is subjected to hydrogen crushing and air flow grinding to obtain NdFeB magnetic powder with an average particle size of 3 μm-5 μm;

[0073] Pure CoFe alloy powder is passed through a vacuum gas atomization powder making system to obtain a powder with an average particle size of 7 μm-8 μm;

[0074] The two powders are mixed in a mixer for 3 hours to obtain mixed magnetic powder, wherein the mass percentage of NdFeB magnetic powder is 90% and the mass percentage of CoFe alloy powder is 10%;

[0075] The mixed magnetic powder was pressed into shape under an orientation field of 2.4 T, and then cold isostatically pressed under a pressure of 180 MPa to obtain a green magnet;

[0076] The green magnet was placed in a vacuum hot pressing sintering furnace and sintered at 1000℃ for 8 minutes under a pressure of 20MPa; then sintered at 1100℃ in a vacuum sintering furnace for 0.5h and cooled; finally, the primary tempering was carried out at 850℃ for 3h and the secondary tempering was carried out at 480℃ for 3h. After completion, it was gas quenched and air cooled, cooled to room temperature and then taken out of the furnace to obtain NdFeB permanent magnet material.

[0077] Example 3

[0078] This embodiment adopts the same implementation as that of embodiment 2, except that the average particle size of the cobalt metal powder is between 10 μm and 12 μm. Other processes are the same as those of embodiment 2.

[0079] Example 4

[0080] This embodiment adopts the same implementation as that of embodiment 2, except that the average particle size of the cobalt metal powder is between 14 μm and 16 μm. Other processes are the same as those of embodiment 2.

[0081] Example 5

[0082] This embodiment adopts the same implementation as that of embodiment 2, except that the average particle size of the cobalt metal powder is between 18 μm and 20 μm. Other processes are the same as those of embodiment 2.

[0083] Example 6

[0084] In this embodiment, the chemical formula of NdFeB magnetic powder is (NdPr) 31 oeLh 0.15 Al 0.1 Zr 0.15 Fe bal. B 0.94 , the cobalt metal powder adopts CoAl alloy powder.

[0085] The preparation of NdFeB permanent magnet materials is as follows:

[0086] The raw materials with purity greater than 99% are classified into (NdPr) 31 oeLh 0.15 Al 0.1 Zr 0.15 Fe bal. B 0.94 The alloy sheet with a thickness of 0.3 mm is prepared by using the quick-setting process; the alloy sheet is subjected to hydrogen crushing and air flow grinding to obtain NdFeB magnetic powder with an average particle size of 7 μm-8 μm;

[0087] The CoAl alloy powder is passed through a vacuum gas atomization powder making system to obtain a powder with an average particle size of 10 μm-12 μm;

[0088] The two powders are mixed in a mixer for 1 hour to obtain mixed magnetic powder, wherein the mass percentage of NdFeB magnetic powder is 99.5% and the mass percentage of CoAl alloy powder is 5%;

[0089] The mixed magnetic powder is pressed into shape under an orientation field of 2.5 T, and then cold isostatically pressed under a pressure of 200 MPa to obtain a green magnet;

[0090] The green magnet is placed in a vacuum hot pressing sintering furnace and sintered at 800℃ for 10 minutes under a pressure of 400MPa; then it is sintered at 1000℃ in a vacuum sintering furnace for 10 hours and cooled; finally, it is tempered at 880℃ for 2.5 hours and at 550℃ for 2.5 hours. After that, it is gas quenched and air cooled, cooled to room temperature and then taken out of the furnace to obtain NdFeB permanent magnet material.

[0091] Example 7

[0092] This embodiment adopts the same implementation as that of the sixth embodiment, except that the cobalt metal powder adopts CoCu alloy powder. The other processes are the same as those of the sixth embodiment.

[0093] Example 8

[0094] This embodiment adopts the same implementation as that of Embodiment 6, except that the mass percentage of the CoAl alloy powder in the mixed magnetic powder is 0.5%.

[0095] Example 9

[0096] This embodiment adopts the same implementation as that of Embodiment 6, except that the mass percentage of the CoAl alloy powder in the mixed magnetic powder is 2%.

[0097] Example 10

[0098] This embodiment adopts the same implementation as that of Embodiment 6, except that the mass percentage of CoAl alloy powder in the mixed magnetic powder is 3%.

[0099] Test Example 2

[0100] The relevant performance tests of the NdFeB permanent magnet materials in Examples 2-10 were carried out with reference to the test method in Test Example 1. The test results are shown in Table 2.

[0101] Table 2 Test results of NdFeB permanent magnet materials

[0102]

[0103] It can be seen from the above embodiments and comparative examples that the preparation method of the NdFeB permanent magnet material in the present invention can effectively improve the high temperature stability of the permanent magnet material when a very small amount of Co is used.

[0104] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0105] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing a neodymium iron boron permanent magnet material, characterized in that: The following steps are involved: Provide NdFeB magnetic powder and cobalt metal powder respectively, wherein the cobalt metal powder is at least one of cobalt powder and cobalt alloy powder, and the cobalt alloy powder is at least one of CoFe alloy powder, CoAl alloy powder and CoCu alloy powder; The NdFeB magnetic powder and the cobalt metal powder are mixed to form a mixed magnetic powder, wherein the NdFeB magnetic powder accounts for 90%-99.5% by mass and the cobalt metal powder accounts for 0.5%-10% by mass. The mixed magnetic powder is sequentially subjected to orientation molding, hot pressing sintering, sintering and tempering treatment to obtain a NdFeB permanent magnet material. The hot pressing sintering process is as follows: at a pressure of 20MPa-400MPa and a vacuum degree of less than 10 -1 , sintering for 5-10 minutes at a temperature of 800℃-1100℃.

2. The preparation method according to claim 1, characterized in that The composition of the NdFeB magnetic powder is (Nd, Pr) by mass percentage. x Fe (100-x-y-z) B y M z , wherein 29%≤x≤33%, 0.80%≤y≤1.0%, 0<z≤4%; and M is at least one of Al, Cu, and Ga.

3. The preparation method according to claim 1 or 2, characterized in that: The NdFeB magnetic powder is jet-milled NdFeB magnetic powder, which is obtained by jet-milling process.

4. The preparation method according to claim 1, characterized in that: The particle size of the NdFeB magnetic powder is between 2 μm and 10 μm.

5. The preparation method according to claim 1, characterized in that: The cobalt metal powder is prepared by an atomization or evaporation condensation process, and has a particle size D50≤30 μm.

6. The preparation method according to claim 1, characterized in that: The specific process of the orientation molding is: the mixed magnetic powder is oriented and pressed at a magnetic field strength of 2.3T-2.5T, and then isostatically pressed at 150-200MPa.

7. The preparation method according to claim 1, characterized in that: The sintering process is: sintering for 0.5-10h at a temperature of 1000-1100°C in a vacuum or protective atmosphere; the protective atmosphere is a rare gas or nitrogen.

8. The preparation method according to claim 1, characterized in that: The tempering process is: two-stage tempering treatment in vacuum or protective atmosphere, wherein the temperature of the first tempering treatment is 850-900°C and the treatment time is 2-3h; the temperature of the second tempering treatment is 480-550°C and the treatment time is 2-3h.

9. A neodymium iron boron permanent magnet material, characterized in that: The method is prepared according to any one of claims 1 to 8.

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