Anisotropic nanocrystalline rare earth permanent magnet material with high remanence, high coercivity and high resistivity, preparation method and application thereof

Abstract

The present invention relates to the technical field of rare earth permanent magnet materials. The present invention provides an anisotropic nanocrystalline rare earth permanent magnet material with high remanence, high coercivity, and high resistivity, as well as a preparation method and application thereof. The permanent magnet material is prepared from raw materials comprising the following mass fractions: 98-99.99% alloy powder and 0.01-2% diamond powder. The diamond powder in the present invention has a particle size of 5-1000 nm and exhibits properties such as a high melting point, high hardness, excellent thermal conductivity, and non-conductivity. It is not easily melted during hot pressing and thermal deformation. The diamond powder can be evenly distributed at the interface of the magnetic powder, effectively reducing the holding time before deformation processing, inhibiting interfacial grain growth, and improving the resistivity of the magnet. The permanent magnet material obtained by the present invention has excellent magnetic properties. By adding a specific amount of nanodiamond powder, the coercivity of the magnet is significantly increased without seriously damaging the remanence of the magnet, thus combining high remanence, high coercivity, and high resistivity.

Description

Technical Field

[0001] The present invention relates to the technical field of rare earth permanent magnet materials, and in particular to an anisotropic nanocrystalline rare earth permanent magnet material with high remanence, high coercivity and high resistivity, and a preparation method and application thereof. Background Art

[0002] RE-Fe-B permanent magnet materials are widely used in the field of permanent magnet motors due to their excellent comprehensive hard magnetic properties. However, due to their high electrical conductivity, low Curie temperature, and high absolute value of the coercive force temperature coefficient, eddy current losses will be generated during the service of the permanent magnet motor, causing the temperature of the magnet to rise, thereby causing thermal demagnetization effect, making the service stability of the magnet poor. Nanocrystalline rare earth permanent magnet materials are one of the current research hotspots of rare earth permanent magnet alloy materials because their temperature stability and fracture toughness are superior to those of traditional micron-crystalline rare earth permanent magnet materials. Hot pressing / hot deformation process is one of the mainstream methods for preparing full-density anisotropic nanocrystalline RE-Fe-B magnets. Since Re2Fe 14 B grains have anisotropy of Young's modulus, that is, the Young's modulus along the a and b axes is much greater than the Young's modulus along the c axis. Under the action of uniaxial pressure, RE-Fe-B crystals achieve preferential growth orientation through crystal plane slip, grain rotation, and "dissolution-precipitation" mechanism, forming a c-axis oriented texture parallel to the pressure direction. 14 Composed of a B-based phase and an RE-rich phase, the magnetic properties of hot-deformed magnets, especially the remanence and magnetic energy product, are closely related to the orientation of the main phase grains. The non-ferromagnetic RE-rich phase not only provides atomic diffusion channels and wets grain boundaries during the hot deformation process, but the uniform distribution of the RE-rich phase also reduces exchange coupling between the main phase grains, thereby increasing the coercivity of the magnet. However, due to the rough surface of the rapidly quenched magnetic powder and insufficient contact between the flaky magnetic powders, stress concentration occurs at the contact interface. At high temperatures, heat easily accumulates at the powder interface, causing abnormal growth of coarse grains at the interface and the appearance of quasi-periodic coarse grains within the magnet. This results in the actual coercivity of hot-deformed magnets being far lower than expected from theoretical values.

[0003] To address the problems of locally coarse grains, uneven microstructure, and low coercivity within magnets, an invention patent (CN201610847457.5) discloses a method for suppressing local grain coarsening, improving the uniformity of the microstructure of heat-deformed magnets, and thereby increasing their coercivity by adding graphene. However, graphene has a large specific surface area and high surface energy, and strong van der Waals forces exist between the layers, making it difficult to evenly disperse the graphene and causing significant agglomeration. Agglomerated graphene can seriously deteriorate the magnetic properties of the magnet. Furthermore, graphene has high electrical conductivity, so adding graphene reduces the resistivity of heat-deformed magnets, increases eddy current losses, and reduces the service stability of NdFeB magnets. An invention patent (CN202010169811.X) discloses a method for increasing the resistivity of heat-deformed magnets by coating them with nano-inorganic insulating materials. However, the introduction of a large amount of non-magnetic phases significantly reduces the magnetic properties of the magnets. Patent CN110098026A discloses a method for improving the strength and surface hardness of bonded rare earth permanent magnets by adding diamond. However, excessive addition of binder to bonded magnets results in severe magnetic dilution, resulting in low magnetic properties and limiting their scope of application. In summary, improving the microstructure and enhancing the magnetoelectric properties of nanocrystalline thermally deformed magnets is of great significance. Summary of the Invention

[0004] The purpose of the present invention is to overcome the problems existing in the prior art and provide an anisotropic nanocrystalline rare earth permanent magnet material with high remanence, high coercivity and high resistivity, as well as a preparation method and application thereof.

[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 an anisotropic nanocrystalline rare earth permanent magnet material with high remanence, high coercivity and high resistivity, which is prepared from raw materials containing the following mass fractions:

[0007] Alloy powder 98-99.99%, diamond powder 0.01-2%.

[0008] As an advantage, the alloy powder is Re x Fe 100-x-y-z TM y B z ; Re is one or more of La, Ce, Pr, Nd, Y, Dy, and Tb, and TM is one or more of Co, Zr, Cr, V, Nb, Si, Ti, Mo, Mn, W, Ga, Cu, Al, and Zn;

[0009] Among them, 26.0≤x≤36.0, 0.14≤y≤8.0, 0.8≤z≤1.36.

[0010] Preferably, the particle size of the diamond powder is 5 to 1000 nm.

[0011] The present invention also provides a method for preparing the anisotropic nanocrystalline rare earth permanent magnet material with high remanence, high coercivity and high resistivity, comprising the following steps:

[0012] (1) The alloy powder and diamond powder are mixed and then densified to obtain an isotropic magnet;

[0013] (2) The isotropic magnet is subjected to thermal deformation orientation treatment to obtain the anisotropic nanocrystalline rare earth permanent magnet material.

[0014] Preferably, the densification treatment environment in step (1) is a vacuum environment or an argon atmosphere, and the vacuum degree of the vacuum environment is greater than or equal to 1*10 -2 Pa; the temperature of the densification treatment is 400 to 750°C or 20 to 30°C, the pressure of the densification treatment is 100 to 700 MPa, and the time of the densification treatment is 3 to 10 min.

[0015] Preferably, the environment of the thermal deformation orientation treatment in step (2) is a vacuum environment or an argon atmosphere, and the vacuum degree of the vacuum environment is greater than or equal to 10 Pa; the temperature of the thermal deformation orientation treatment is 650-850°C, the pressure of the thermal deformation orientation treatment is 20-250 MPa, and the rate of the thermal deformation orientation treatment is 0.01-0.5 mm / s.

[0016] Preferably, the thermal deformation orientation treatment in step (2) is performed by thermal deformation circular cake treatment or back extrusion circular ring treatment; the deformation amount of the thermal deformation circular cake treatment is 30 to 80%.

[0017] Preferably, the pressure of the heat-deformed round cake treatment in step (2) is 20 to 250 MPa.

[0018] The present invention also provides the application of the anisotropic nanocrystalline rare earth permanent magnet material with high remanence, high coercive force and high resistivity in the field of permanent magnet motors.

[0019] The beneficial effects of the present invention are:

[0020] 1. The anisotropic nanocrystalline rare earth permanent magnet material prepared by the present invention has a certain improvement in magnetic properties compared with alloy powder; and by adding a specific mass fraction of nanodiamond powder, the coercive force of the magnet can be greatly improved without causing serious damage to the remanence of the magnet.

[0021] 2. The nano-diamond powder added in the present invention has the characteristics of high melting point, high hardness, excellent thermal conductivity and non-conductivity. The characteristics of high melting point and high hardness make the nano-diamond powder difficult to melt during hot pressing and thermal deformation, and can be evenly distributed on the contact interface of the rapidly quenched magnetic powder particles, which can inhibit the formation of coarse grains and RE2Fe 14 B grain growth; excellent thermal conductivity makes the diamond powder evenly distributed at the interface of magnetic powder, avoiding local overheating due to insufficient contact of magnetic powder at high temperature, shortening the time required for the magnet as a whole to reach the set temperature, reducing the holding time before deformation treatment, thereby achieving the purpose of inhibiting the overall grain growth of the magnet and improving the comprehensive magnetic properties of the magnet; the insulating properties make the diamond powder evenly distributed at the contact interface of the rapidly quenched magnetic powder particles, improving the resistivity of the magnet. In addition, the refinement of the grains in the coarse-grained area leads to an increase in the number of grain boundaries. Free electrons will scatter in different directions when encountering crystal defects, resulting in a decrease in electron conduction efficiency. Ultimately, the magnetic properties and resistivity of the magnet are simultaneously improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a microscopic morphology of the nano-diamond powder of Example 1;

[0023] Figure 2 (a) is a microstructure diagram of the anisotropic nanocrystalline rare earth permanent magnet material with a diamond addition of 0.1% prepared in Example 1;

[0024] Figure 2 (b) is a distribution morphology of nano-diamond powder in anisotropic nanocrystalline rare earth permanent magnet material with a diamond addition of 0.1% prepared in Example 1;

[0025] Figure 3 (a) is a fracture morphology of anisotropic nanocrystalline rare earth permanent magnet material with zero diamond addition prepared in Example 2;

[0026] Figure 3 (b) is a fracture morphology of the anisotropic nanocrystalline rare earth permanent magnet material prepared in Example 2 with a diamond addition of 0.1%. DETAILED DESCRIPTION

[0027] The present invention provides an anisotropic nanocrystalline rare earth permanent magnet material with high remanence, high coercivity and high resistivity, which is prepared from raw materials containing the following mass fractions:

[0028] Alloy powder 98-99.99%, diamond powder 0.01-2%.

[0029] In the present invention, the mass fraction of the alloy powder is 98 to 99.99%, preferably 98.5 to 99.5%, and more preferably 98.8 to 99.2%.

[0030] In the present invention, the mass fraction of the diamond powder is 0.01 to 2%, preferably 0.5 to 1.5%, and more preferably 0.8 to 1.2%.

[0031] In the present invention, the alloy powder is Re x Fe 100-x-y-z TM y B z ; Re is preferably one or more of La, Ce, Pr, Nd, Y, Dy, Tb, and TM is preferably one or more of Co, Zr, Cr, V, Nb, Si, Ti, Mo, Mn, W, Ga, Cu, Al, and Zn;

[0032] Among them, 26.0≤x≤36.0, 0.14≤y≤8.0, 0.8≤z≤1.36.

[0033] In the present invention, the range of x is preferably 26.0≤x≤36.0, more preferably 28.0≤x≤34.0, and even more preferably 30.0≤x≤32.0.

[0034] In the present invention, the range of y is preferably 0.14≤y≤8.0, more preferably 2.0≤y≤6.0, and even more preferably 3.0≤y≤5.0.

[0035] In the present invention, the range of z is preferably 0.8≤z≤1.36, more preferably 0.9≤z≤1.26, and even more preferably 1.0≤z≤1.16.

[0036] In the present invention, the Re x Fe 100-x-y-z TM y B z The alloy powder can be purchased or prepared.

[0037] The present invention provides a x Fe 100-x-y-z TM y B z The method for preparing alloy powder comprises the following steps:

[0038] (a) melting and casting the raw materials in sequence to obtain a RE-Fe-B-TM alloy ingot;

[0039] (b) After removing the surface oxide scale of the RE-Fe-B-TM alloy ingot, mechanical crushing and rapid quenching are performed in sequence to obtain a RE-Fe-B-TM rapid quenching strip;

[0040] (c) Mechanically crushing the RE-Fe-B-TM quenching strip to obtain the Rex Fe 100-x-y-z TM y B z alloy powder.

[0041] In the present invention, the melting method in step (a) is preferably arc melting or induction melting; the melting atmosphere is argon; the melting temperature is preferably 1200°C to 1500°C, more preferably 1230°C to 1400°C, and more preferably 1250°C to 1350°C.

[0042] In the present invention, the quenching method of step (b) is preferably melt quenching or induction quenching; the quenching rate is preferably 15 to 40 m / s, more preferably 20 to 35 m / s, and more preferably 25 to 30 m / s.

[0043] In the present invention, the particle size of the diamond powder is preferably 5 to 1000 nm, more preferably 50 to 800 nm, and even more preferably 200 to 600 nm.

[0044] In the present invention, the rare earth permanent magnet material is composed of the main phase Re2Fe 14 It is composed of B phase, rare earth-rich phase and nano-diamond. The main phase is flaky grains and diamonds are evenly distributed at the interface of magnetic powder.

[0045] The present invention also provides a method for preparing the anisotropic nanocrystalline rare earth permanent magnet material with high remanence, high coercivity and high resistivity, comprising the following steps:

[0046] (1) The alloy powder and diamond powder are mixed and then densified to obtain an isotropic magnet;

[0047] (2) The isotropic magnet is subjected to thermal deformation orientation treatment to obtain the anisotropic nanocrystalline rare earth permanent magnet material.

[0048] In the present invention, the mixing atmosphere in step (1) is preferably argon, the mixing method is preferably three-dimensional mixing or ball milling mixing, and the mixing time is preferably 1 to 3 hours, more preferably 1.5 to 2.5 hours, and more preferably 1.8 to 2.2 hours.

[0049] In the present invention, the environment of the densification treatment in step (1) is preferably a vacuum environment or an argon atmosphere; the vacuum degree of the vacuum environment is preferably greater than or equal to 1*10 -2 Pa, more preferably greater than or equal to 1.2*10 -2 Pa, more preferably greater than or equal to 1.5*10 -2Pa; the densification treatment is a cold pressing or hot pressing densification treatment; the temperature of the hot pressing densification treatment is preferably 400-750°C, more preferably 450-700°C, and more preferably 500-650°C; the temperature of the cold pressing densification treatment is preferably 20-30°C, more preferably 22-28°C, and more preferably 24-26°C.

[0050] In the present invention, the pressure of the densification treatment is preferably 100-700 MPa, more preferably 200-600 MPa, and more preferably 300-500 MPa; the time of the densification treatment is preferably 3-10 min, more preferably 4-9 min, and more preferably 5-8 min.

[0051] In the present invention, the environment of the thermal deformation orientation treatment in step (2) is preferably a vacuum environment or an argon atmosphere; the vacuum degree of the vacuum environment is greater than or equal to 10Pa, further preferably greater than or equal to 12Pa, more preferably greater than or equal to 15Pa; the temperature of the thermal deformation orientation treatment is preferably 650-850°C, further preferably 700-800°C, more preferably 730-770°C; the rate of the thermal deformation orientation treatment is preferably 0.01-0.5mm / s, further preferably 0.05-0.4mm / s, more preferably 0.1-0.3mm / s.

[0052] In the present invention, the thermal deformation orientation treatment in step (2) is performed by thermal deformation circular cake treatment or back extrusion circular ring treatment; the deformation amount of the thermal deformation circular cake treatment is preferably 30-80%, more preferably 50-75%, and more preferably 60-70%.

[0053] In the present invention, the pressure of the heat-deformed round cake treatment in step (2) is preferably 20 to 250 MPa, more preferably 50 to 200 MPa, and even more preferably 100 to 150 MPa.

[0054] In the present invention, the back-extrusion ring process is to place the isotropic magnet in a mold of specific size and extrude it under dynamic pressure.

[0055] In the present invention, the finishing pressure of the back-extrusion ring treatment is preferably 50 to 300 MPa, more preferably 70 to 250 MPa, and even more preferably 100 to 200 MPa.

[0056] In the present invention, the heating method for the densification treatment in step (1) and the thermal deformation orientation treatment in step (2) is a spark plasma sintering method or an induction heating sintering method.

[0057] The present invention also provides the application of the anisotropic nanocrystalline rare earth permanent magnet material with high remanence, high coercive force and high resistivity in the field of permanent magnet motors.

[0058] The technical solutions provided by the present invention are described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0059] Example 1

[0060] Nd 29.89 Fe 62.62 Co 5.93 Ga 0.64 B 0.92 The alloy powder is mixed with nano-diamond powder with a particle size of 500 nm and placed in a three-dimensional mixer. The mixture is mixed for 2 hours in an argon atmosphere to obtain a uniformly mixed magnetic powder. The uniformly mixed magnetic powder is taken out from an argon-protected glove box (the mass fraction of the nano-diamond powder in the uniformly mixed magnetic powder is 0.1%). The uniformly mixed magnetic powder is placed in a pre-prepared hot pressing mold and subjected to a hot pressing densification treatment at 500° C. and 500 MPa in an argon atmosphere for 5 minutes to obtain an isotropic magnet. The magnet is then subjected to a hot deformation round cake treatment in an argon atmosphere at 750° C. and 150 MPa, with a set rate of 0.1 mm / s and a deformation amount of 70% (the heating method for the densification treatment and the hot deformation round cake treatment is a spark plasma sintering method), to obtain an anisotropic nanocrystalline rare earth permanent magnet material with a diamond addition of 0.1%.

[0061] Keeping other conditions unchanged, the mass fraction of nano-diamond powder in the uniformly mixed magnetic powder was set to 0, 0.2%, 0.3%, 0.4% and 2%, respectively, to obtain anisotropic nanocrystalline rare earth permanent magnet materials with different diamond addition amounts (0, 0.2%, 0.3%, 0.4% and 2%).

[0062] The microscopic morphology of the nano-diamond powder in this embodiment is characterized to obtain a microscopic morphology of the nano-diamond powder, as shown in FIG. Figure 1 As shown; the microstructure of the anisotropic nanocrystalline rare earth permanent magnet material with a diamond addition of 0.1% prepared in this embodiment was characterized to obtain a microstructure diagram of the anisotropic nanocrystalline rare earth permanent magnet material, as shown Figure 2 (a) shows the distribution morphology of nano-diamond powder in anisotropic nanocrystalline rare earth permanent magnet materials, as shown in Figure 2 (b) is shown. Figure 2 (a) It can be seen that the permanent magnet material is made of stacked strip-shaped magnetic powders, and some rare earth-rich phases are distributed at the interface of the magnetic powders; Figure 2 (b) It can be seen that the nanodiamond particles are distributed at the strip interface, inhibiting the grain growth at the interface.

[0063] The magnetic properties of the anisotropic nanocrystalline rare earth permanent magnet materials with diamond addition amounts of 0, 0.1%, 0.2%, 0.3%, 0.4% and 2% in this embodiment were tested respectively, and the performance comparison results are shown in Table 1.

[0064] Table 1 Comparison of magnetic properties of permanent magnet materials with different diamond addition amounts

[0065]

[0066]

[0067] It can be seen from Table 1 that adding an appropriate amount of nanodiamonds can simultaneously improve the magnetic properties and resistivity of anisotropic nanocrystalline rare earth permanent magnet materials; after adding more nanodiamonds, the resistivity of the permanent magnet material increases significantly.

[0068] Example 2

[0069] MM 29.6 Fe 62.6 Co 6.0 Ga 0.6 Al 0.2 B 1.0 The alloy powder is mixed with nano-diamond powder with a particle size of 600 nm and placed in a three-dimensional mixer. The mixture is mixed for 2.2 hours under an argon atmosphere to obtain a uniformly mixed magnetic powder. The uniformly mixed magnetic powder is taken out from an argon-protected glove box (the mass fraction of the nano-diamond powder in the uniformly mixed magnetic powder is 0.1%); the mixture is placed in a pre-prepared hot pressing mold and subjected to a hot pressing densification treatment at 600° C. and 200 MPa in an argon atmosphere for 10 minutes to obtain an isotropic magnet; the magnet is then subjected to a hot deformation disc treatment in an argon atmosphere at 700° C. and 120 MPa, with a set rate of 0.2 mm / s and a deformation amount of 75% (the heating method for the densification treatment and the hot deformation disc treatment is a spark plasma sintering method) to obtain an anisotropic nanocrystalline rare earth permanent magnet material with a diamond addition of 0.1%.

[0070] Among them, MM 29.6 Fe 62.6 Co 6.0 Ga 0.6 Al 0.2 B 1.0 In the rapidly quenched magnetic powder, MM is a mixed rare earth, composed of the following components in mass fractions: Ce 49.8wt%, Nd 25wt%, Pr 25wt%, and Dy 0.2wt%.

[0071] Keeping other conditions unchanged, the mass fraction of nano-diamond powder in the uniformly mixed magnetic powder is set to 0, and anisotropic nano-crystalline rare earth permanent magnet material with 0 diamond addition amount is obtained.

[0072] The fracture morphologies of the anisotropic nanocrystalline rare earth permanent magnet materials with 0 and 0.1% diamond addition obtained in this embodiment were characterized respectively, and the fracture morphologies of the anisotropic nanocrystalline rare earth permanent magnet materials with 0 diamond addition were obtained, as shown in FIG. Figure 3 (a) shows the fracture morphology of anisotropic nanocrystalline rare earth permanent magnet material with a diamond addition of 0.1%, as shown in Figure 3 As shown in (b), the magnet without nanodiamonds has coarse grains and poor orientation. However, after adding nanodiamonds, the grain size at the contact interface of the magnetic powder is significantly reduced, the grains in the fine-grained area are even finer, and the orientation is more regular, resulting in a significant improvement in magnet performance.

[0073] The magnetic properties of the anisotropic nanocrystalline rare earth permanent magnet materials with diamond additions of 0 and 0.1% in this embodiment were tested respectively, and the performance comparison results are shown in Table 2.

[0074] Table 2 Comparison of magnetic properties of permanent magnet materials with diamond addition of 0 and 0.1%

[0075]

[0076] Example 3

[0077] Ce 33 Fe 65.15 Ga 0.5 B 1.35 The alloy powder was mixed with nano-diamond powder with a particle size of 700 nm and placed in a three-dimensional mixer. The mixture was mixed for 1.9 h under an argon atmosphere to obtain a uniform mixed magnetic powder. The uniform mixed magnetic powder (the mass fraction of the nano-diamond powder in the uniform mixed magnetic powder was 0.1%) was taken out from an argon-protected glove box and placed in a pre-prepared hot pressing mold. The mixture was heated to a vacuum degree of 1.2*10 -2 Pa environment, hot pressing densification treatment was carried out at 550℃ and 200MPa for 5 minutes to obtain an isotropic magnet; then the magnet was subjected to heat deformation round cake treatment at 700℃ and 200MPa in a vacuum environment of 12Pa, with a set rate of 0.3mm / s and a deformation amount of 65% (the heating method for densification treatment and heat deformation round cake treatment was induction heating sintering method), to obtain an anisotropic nanocrystalline rare earth permanent magnet material with a diamond addition of 0.1%.

[0078] Keeping other conditions unchanged, the mass fraction of nano-diamond powder in the uniformly mixed magnetic powder was set to 0, 0.4% and 0.8%, respectively, to obtain anisotropic nanocrystalline rare earth permanent magnet materials with different diamond addition amounts (0, 0.4% and 0.8%).

[0079] The magnetic properties of the anisotropic nanocrystalline rare earth permanent magnet materials with diamond addition amounts of 0%, 0.1%, 0.4% and 0.8% in this embodiment were tested respectively, and the performance comparison results are shown in Table 3.

[0080] Table 3 Comparison of magnetic properties of permanent magnet materials with different diamond addition amounts

[0081]

[0082] Example 4

[0083] Nd 29.8 Fe 68.6 Ga 0.4 Ti 0.15 Si 0.1 B 0.95 The alloy powder was mixed with nano-diamond powder with a particle size of 650 nm and placed in a three-dimensional mixer. The mixture was mixed for 2 h under an argon atmosphere to obtain a uniform mixed magnetic powder. The uniform mixed magnetic powder was taken out from an argon-protected glove box (the mass fraction of the nano-diamond powder in the uniform mixed magnetic powder was 0.5%) and placed in a pre-prepared hot pressing mold. The mixture was heated to a vacuum degree of 1.4*10 -2 Pa environment, hot pressing densification treatment was carried out at 660℃ and 200MPa for 4 minutes to obtain an isotropic magnet; then the magnet was placed in a back extrusion mold for back extrusion ring treatment in a vacuum environment of 14Pa, and the rate was set to 0.2mm / s, the temperature was 850℃, and the ending pressure was 150Mpa. The heating method for the densification treatment and the back extrusion ring treatment was induction heating sintering, and a back-extruded magnetic ring with an outer diameter of 30mm, an inner diameter of 26mm, and a wall thickness of 2mm with a c-axis texture and a diamond addition of 0.5% was obtained.

[0084] Keeping other conditions unchanged, the mass fraction of nano-diamond powder in the uniformly mixed magnetic powder was set to 0, and a back-extrusion magnetic ring with an outer diameter of 30 mm, an inner diameter of 26 mm, and a wall thickness of 2 mm and a c-axis texture was obtained with 0 diamond addition.

[0085] The magnetic properties of the back-extrusion magnetic rings with diamond additions of 0% and 0.5% in this embodiment were tested respectively, and the performance comparison results are shown in Table 4.

[0086] Table 4 Comparison of magnetic properties of back-extrusion magnetic rings with diamond addition of 0 and 0.5%

[0087]

[0088]

[0089] Example 5

[0090] Nd 29.89Fe 62.62 Co 5.93 Ga 0.64 B 0.92 The alloy powder is mixed with nano-diamond powder with a particle size of 450 nm and placed in a three-dimensional mixer. The mixture is mixed for 1.8 hours under an argon atmosphere to obtain a uniformly mixed magnetic powder. The uniformly mixed magnetic powder is taken out from an argon-protected glove box (the mass fraction of the nano-diamond powder in the uniformly mixed magnetic powder is 0.1%); the uniformly mixed magnetic powder is placed in a pre-prepared cold pressing mold and subjected to a cold pressing densification treatment at 25° C. and 350 MPa in an argon atmosphere for 10 minutes to obtain an isotropic magnet; the magnet is then subjected to a heat deformation round cake treatment in an argon atmosphere at 710° C. and 170 MPa, with a set rate of 0.15 mm / s and a deformation amount of 55% (the heating method for the densification treatment and the heat deformation round cake treatment is a spark plasma sintering method) to obtain an anisotropic nanocrystalline rare earth permanent magnet material with a diamond addition of 0.1%.

[0091] Keeping other conditions unchanged, the mass fraction of nano-diamond powder in the uniformly mixed magnetic powder is set to 0, and anisotropic nano-crystalline rare earth permanent magnet material with 0 diamond addition amount is obtained.

[0092] The magnetic properties of the anisotropic nanocrystalline rare earth permanent magnet materials with diamond additions of 0 and 0.1% in this embodiment were tested respectively, and the performance comparison results are shown in Table 5.

[0093] Table 5 Comparison of magnetic properties of permanent magnet materials with diamond addition of 0 and 0.1%

[0094]

[0095] It can be seen from the above examples that the anisotropic nanocrystalline rare earth permanent magnet material prepared by the present invention has a certain improvement in magnetic properties compared to alloy powder; and by adding a specific mass fraction of nanodiamond powder, the coercive force of the magnet can be greatly improved without causing serious damage to the remanence of the magnet.

[0096] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. An anisotropic nanocrystalline rare earth permanent magnet material with high remanence, high coercivity and high resistivity, characterized in that: Prepared from raw materials containing the following mass fractions: Alloy powder 98~99.99%, diamond powder 0.01~2%; The rare earth permanent magnet material is composed of the main phase Re2Fe 14 It is composed of B phase, rare earth-rich phase and nano-diamonds. The main phase is flaky grains, and diamonds are evenly distributed at the interface of magnetic powder. The method for preparing the anisotropic nanocrystalline rare earth permanent magnet material with high remanence, high coercivity and high resistivity comprises the following steps: (1) The alloy powder and diamond powder are mixed and then densified to obtain an isotropic magnet; (2) subjecting the isotropic magnet to thermal deformation orientation treatment to obtain the anisotropic nanocrystalline rare earth permanent magnet material; The thermal deformation orientation treatment in step (2) is performed by thermal deformation disc treatment or back extrusion ring treatment; the pressure of the thermal deformation disc treatment is 100~150MPa; the back extrusion ring treatment is to place the isotropic magnet in a mold of a specific size and extrude it under dynamic pressure, and the end pressure of the back extrusion ring treatment is 100~200MPa.

2. The anisotropic nanocrystalline rare earth permanent magnet material according to claim 1, characterized in that: The alloy powder is Re x Fe 100-x-y-z TM y B z ; Re is one or more of La, Ce, Pr, Nd, Y, Dy, and Tb, and TM is one or more of Co, Zr, Cr, V, Nb, Si, Ti, Mo, Mn, W, Ga, Cu, Al, and Zn; Among them, 26.0≤x≤36.0, 0.14≤y≤8.0, 0.8≤z≤1.

36.

3. The anisotropic nanocrystalline rare earth permanent magnet material according to claim 1, characterized in that: The particle size of the diamond powder is 5-1000 nm.

4. The method for preparing the anisotropic nanocrystalline rare earth permanent magnet material with high remanence, high coercivity and high resistivity according to any one of claims 1 to 3, characterized in that: It includes the following steps: (1) The alloy powder and diamond powder are mixed and then densified to obtain an isotropic magnet; (2) subjecting the isotropic magnet to thermal deformation orientation treatment to obtain the anisotropic nanocrystalline rare earth permanent magnet material; The thermal deformation orientation treatment in step (2) is performed by thermal deformation disc treatment or back extrusion ring treatment; the pressure of the thermal deformation disc treatment is 100~150MPa; the back extrusion ring treatment is to place the isotropic magnet in a mold of a specific size and extrude it under dynamic pressure, and the end pressure of the back extrusion ring treatment is 100~200MPa.

5. The preparation method according to claim 4, wherein The densification process in step (1) is performed in a vacuum environment or an argon atmosphere, and the vacuum degree of the vacuum environment is greater than or equal to 1*10 -2 Pa; the temperature of the densification treatment is 400~750℃ or 20~30℃, the pressure of the densification treatment is 100~700MPa, and the time of the densification treatment is 3~10min.

6. The preparation method according to claim 4 or 5, characterized in that The environment of the thermal deformation orientation treatment in step (2) is a vacuum environment or an argon atmosphere, and the vacuum degree of the vacuum environment is greater than or equal to 10 Pa; the temperature of the thermal deformation orientation treatment is 650~850℃, and the rate of the thermal deformation orientation treatment is 0.01~0.5mm / s.

7. The preparation method according to claim 6, wherein The deformation amount of the heat-deformed round cake in step (2) is 30-80%.

8. Application of the anisotropic nanocrystalline rare earth permanent magnet material with high remanence, high coercivity and high resistivity according to any one of claims 1 to 3 in the field of permanent magnet motors.

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