JP7371108B2 - Rare earth diffusion magnet manufacturing method and rare earth diffusion magnet - Google Patents

Description

The present invention relates to the production of rare earth magnets, and particularly to a method for producing rare earth diffused magnets and a rare earth diffused magnet.

Sintered NdFeB magnets have excellent magnetic properties and are widely used in many fields such as electronic information, automobile industry, medical equipment, energy transportation, etc. In recent years, new applications have emerged in the fields of energy conservation and environmental protection, such as wind power generation, energy-saving home appliances, and new energy vehicles. Using the grain boundary diffusion method, heavy rare earth elements are diffused into the grain boundaries and edge regions of the main phase grains of the magnet. Thereby, the objective of increasing the anisotropic magnetic field of the magnet can be achieved without significantly reducing the residual magnetism and magnetic energy product.

The existing rare earth magnet manufacturing method uses a continuous pass magnetron sputtering device to sputter heavy rare earth metals such as Dy and Tb onto the surface of the magnet, effectively controlling the thickness and uniformity of the sputtered layer. , it is possible to realize rapid and continuous production of magnets using grain boundary diffusion technology. However, this method quickly consumes the Dy/Tb target during sputtering, and heavy rare earths are expensive, which increases the manufacturing cost of the magnet.

Another method produces grain boundary diffused rare earth permanent magnet materials by chemical vapor deposition of composite target materials. Through the deposition of composite target material, medium-high temperature treatment, and low-temperature aging treatment, the coercive force of the magnet is obviously improved, and the residual magnetism and magnetic energy product are basically not reduced. Composite target materials can improve the performance of magnets, but the inventor believes that during the diffusion process of composite targets, the light rare earth elements that originally exist inside the magnets diffuse to the surface due to the difference in concentration, causing the surface of the magnet to It was discovered that a rare earth-rich layer was formed in the area. Such a rare earth rich layer is easily oxidized and deteriorates the corrosion resistance of the magnet.

In order to solve the above problems, the present invention provides a method for manufacturing a rare earth diffused magnet and a rare earth diffused magnet, controls the content of RL in the sputtering plating layer, and the obtained rare earth diffused magnet has a high overall It has magnetic properties and excellent corrosion resistance.

Embodiments of the present invention provide a method of manufacturing a rare earth diffused magnet, including the following steps:
Step A. A first target material is sputtered onto a substrate to form a first plating layer on the surface of the substrate, and the composition of the first target material is RH _x -RL _y -M _z in mass percent. However, RH is one or more of Dy, Tb, or Ho, RH includes at least one of Dy or Tb, RL is one or more of Nd, Pr, Ce, La, and Y, and RL is Contains at least one of Nd or Pr, M is at least one element of Co, Cu, Ga, Ag, Sn or Al, y is 22 to 28 wt%, z is 0 to 20 wt%, x is (100-yz)wt%, and the base material is a rare earth magnet;
Step B. A step of performing a diffusion treatment on the sputtered base material to obtain a rare earth diffused magnet.

Preferably, in the method for manufacturing a rare earth diffused magnet, y is 25 to 28 wt%, and z is 0 to 12 wt%.

In the method for manufacturing a rare earth diffused magnet, the first plating layer has a thickness of 2 to 20 μm.

In step A of the method for manufacturing a rare earth diffused magnet, after the first target material is sputtered, a second target material is sputtered to form a second plating layer on the first plating layer, and the second plating layer is formed on the first plating layer. The composition of the target material is at least one of Cr, Ti, W, Mo, Si, _{Al2O3 ,} or _ZrO2 .

In a preferred embodiment of the present invention, the second plating layer has a thickness of 0.1 to 6 μm.

The above method for manufacturing a rare earth diffused magnet further includes manufacturing the base material before the step A, and the manufacturing of the base material includes forming alloy flakes by melting and rapid solidification of raw materials, and forming the alloy flakes by melting and rapidly solidifying raw materials. The flakes are subjected to hydrogen crushing and jet mill treatment to obtain an alloy powder, the alloy powder is pressed in a magnetic field to obtain a press molded body, and the press molded body is sent to a sintering furnace to be sintered. The method includes obtaining a sintered magnet, and slicing the sintered magnet to obtain the base material.

In the above method for manufacturing a rare earth diffused magnet, the thickness of the alloy flakes is 0.15 to 0.5 mm.

In the above method for producing a rare earth diffused magnet, the thickness of the base material is 1 to 10 mm.

In the above method for producing a rare earth diffused magnet, the diffusion treatment includes primary heat treatment: keeping warm at 800 to 1000°C for 2 to 18 hours, and secondary heat treatment: keeping warm at 450 to 600°C for 3 to 8 hours. .

The present invention also provides a rare earth diffused magnet manufactured by the method for manufacturing a rare earth diffused magnet.

In the rare earth diffused magnet manufacturing method and rare earth diffused magnet of the present invention, the content of the RL element in the plating layer is close to the content of the RL element in the base material, and when diffusing, the heavy rare earth element is transferred to the base material. However, since the RL elements in the base material are not concentrated on the surface, a rare earth rich layer is not formed on the surface of the rare earth diffused magnet, and the corrosion resistance of the rare earth diffused magnet is improved.

FIG. 3 is a schematic diagram of the structure of a sputtered substrate according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to provide a better understanding of embodiments of the present invention and their respective advantages, modes for carrying out the present invention will now be described in more detail in conjunction with the accompanying drawings and examples. However, the specific embodiments and examples described below are merely illustrative of the invention and are not intended to limit the invention.

The "connection" referred to in the present invention is to be understood in a broad sense, unless explicitly specified or limited otherwise, and it can be directly connected or connected via an intermediate. In the description of the present invention, directions or positional relationships indicated by "top", "bottom", "front", "rear", "left", "right", "upper end", "lower end", etc. This is the orientation or positional relationship shown based on the drawing. This is not intended to indicate or imply that the referenced devices or elements must have any particular orientation or be constructed or operated in any particular orientation, but rather are intended to illustrate the invention. , is merely a convenience to simplify the explanation. Therefore, these descriptions should not be construed as limitations on the invention.

As shown in FIG. 1, the rare earth diffused magnet according to the embodiment of the present invention can be obtained by forming a plating layer on a base material 1 by sputtering, and then performing a diffusion treatment on the sputtered base material. It will be done. The base material is a rare earth magnet. During sputtering, the base material passes under the first target material to form a first plating layer 21 on the surface of the base material. If necessary, a second target material is provided after the first target material, and after the base material passes through the first target material, the second target material is sputtered to form a second plating on the first plating layer 21. A layer 22 may also be formed. The second plating layer 22 can further improve the performance of the rare earth diffused magnet. After the sputtering of one surface of the substrate is completed, a subsequent thermal diffusion treatment may be performed, and if necessary, the substrate may be turned over and the thermal diffusion treatment may be performed after sputtering on another surface. Generally, the two sputtered surfaces of the substrate will be opposite each other, and the sputtered surface will be the surface perpendicular to the magnetization direction of the substrate.

The above method for manufacturing a rare earth diffused magnet in an embodiment of the present invention may include a process for manufacturing a base material. The production of the base material is
S1, blend the raw materials according to the composition of the base material, and create alloy flakes by melting and rapid solidification of the raw materials, preferably the thickness of the alloy flakes is 0.15 ~ 0.15 to facilitate subsequent processing. a step controlled to be 0.5 mm;
S2, hydrogen crush the alloy flakes, preferably perform dehydrogenation at 540 ° C. for 6 hours, and make the hydrogen content after dehydrogenation 1200 ppm to obtain a moderately crushed powder; into a jet mill to produce fine powder to obtain an alloy powder with D50=4.0 μm;
S3, pressing the alloy powder in a magnetic field, preferably at a magnetic field strength of 1.8T to obtain a pressed body;
S4, placing the press molded body in a sintering furnace and sintering it, preferably at a sintering temperature of 1000°C and a heat retention time of 6 hours to obtain a sintered magnet;
S5, including the step of pickling the surface of the sintered magnet to degrease it, and then slicing it to obtain a base material.
The thickness of the base material is preferably 1 to 10 mm.

After the substrate was obtained, subsequent processing was performed on the substrate to obtain a rare earth diffused magnet. The specific steps are as follows.

Step A. Sputter onto the base material. Preferably, the sputtering conditions are as follows. The temperature is 100 to 200°C, the deposition pressure per unit area is 1 to 30 Pa under argon gas conditions, the speed of the substrate passing through the sputtering zone is 0.01 to 1.0 m/s, and the sputtering target is The vertical distance between the material and the top surface of the substrate is 10 to 200 mm.

The substrate passes under the first target material, and the first target material is sputtered to form a first plating layer on the surface of the substrate. The composition of the first target material is RH _x -RL _y -M _z in mass percent. However, RH is one or more of Dy, Tb, or Ho, RH includes at least one of Dy or Tb, RL is one or more of Nd, Pr, Ce, La, and Y, and RL is Contains at least one of Nd or Pr, M is at least one element of Co, Cu, Ga, Ag, Sn or Al, y is 22 to 28 wt%, z is 0 to 20 wt%, x is (100-yz)wt%, and the base material is a rare earth magnet. In this embodiment, z may be 0, ie, the first target material does not contain M.

Step B. A diffusion treatment is performed on the sputtered base material to obtain a rare earth diffused magnet. Preferably, the diffusion treatment includes a primary heat treatment: incubation at 800°C to 1000°C for 2 to 18 hours, and a secondary heat treatment: incubation at 450°C to 600°C for 3 to 8 hours.

After sputtering a heavy rare earth plating layer on the surface of the base material, a diffusion treatment is performed on the heavy rare earth plating layer, which is a diffusion source, at a high temperature, and the rare earth in the diffusion source is diffused into the grain boundary phase and main phase of the base material. In the diffusion process, the RH element in the plating layer diffuses along the grain boundaries, replaces the RL element in the main phase, and forms a core-shell structure around the crystal grains of the main phase. After the RL element was substituted in the main phase, it diffused into the grain boundaries of the main phase. When a concentration gradient is formed with the rare earth in the surface layer of the base material, the RL element in the grain boundary phase diffuses to the surface of the base material. In this embodiment, the content of RL elements in the diffusion source is relatively close to the RL elements inside the substrate. During diffusion, the heavy rare earths in the diffusion source continue to diffuse into the interior of the substrate because a concentration difference with the interior of the substrate still exists. Since the difference between the concentration of the RL element in the diffusion source and the concentration inside the base material was small, the driving force for the light rare earth elements in the base material to diffuse to the surface and form a rare earth rich layer was suppressed. No rare earth rich layer is formed on the surface of the material. This improves the corrosion resistance of the rare earth diffused magnet. If the content of the RL element contained in the target material is too large, the concentration of heavy rare earth elements will decrease, and the final specific coercive force Hcj of the magnet will not be sufficiently improved. Moreover, if the content of the RL element is too small, it will not be sufficient to suppress surface concentration of the RL element within the base material. The target material may contain a small amount of Cu or Al or Co, further accelerating the diffusion of the metal atoms of the RH element, thereby increasing the coercive force of the magnet. Depending on the composition of the base material, the composition of the plating layer can be appropriately adjusted so that the content of the RL element in the plating layer is less than the content of the RL element in the base material.

Preferably, in the method for manufacturing a rare earth diffused magnet, y of the first target material is 25 to 28 wt%, and z is 0 to 12 wt%.

Preferably, the first plating layer has a thickness of 2 to 20 μm. If the thickness of the first plating layer is too thin, this will affect the increase in the intrinsic coercive force Hcj, but if the thickness of the first plating layer is too thick, the target material will be wasted.

In step A above, after the first target material is sputtered, the second target material is sputtered onto the base material to form a second plating layer on the first plating layer. The composition of the second target material is _at least one of Cr, Ti, W, Mo, Si, _Al2O3 , or _ZrO2 .

The second plating layer can further improve the corrosion resistance of the rare earth diffusion magnet, and due to the coating with the second plating layer, the loss of rare earth elements in the first plating layer due to volatilization is reduced during diffusion treatment. This further improves the performance of the rare earth diffused magnet. In a preferred embodiment, the thickness of the second plating layer is 0.1 to 6 μm.

(Example 1-1)
The manufacturing process of the rare earth diffused magnet is as follows.

1. Mixing of raw materials Raw materials are mixed according to the composition mass ratio of the base material C1 and the first target material.

The composition of the base material C1 is Nd _22.5 Pr _6.9 Dy _2.6 Co _1.0 Cu _0.1 Ga _0.12 Al _0.3 B _0.98 Fe _bal .

The composition of the first target material is Tb ₆₈ Nd ₂₃ Pr ₄ Al ₅ .

2. Melting The raw material of the substrate C1 is melted and rapidly solidified into thin strips of alloy flakes, the casting temperature of which is 1380 °C, and the thickness of the alloy flakes is controlled to be 0.2-0.5 mm. Ru.

The raw material for the first target material is placed in a vacuum melting furnace and melted in vacuum. The melting temperature is 1050° C., the melting time is 15 minutes, and the alloy ingot is cast and subjected to forging, hot rolling, cold rolling and mechanical processing to form the first target material.

3. Preparation of base material 31. The alloy flakes of the base material C1 are subjected to hydrogen crushing and dehydrogenation is performed at 540° C. for 6 hours, and the hydrogen content after dehydrogenation is set to 1200 ppm to obtain a powder in which the alloy is crushed to a medium degree. The medium crushed powder is put into a jet mill to produce fine powder, and an alloy powder with D50=4.0 μm is obtained.

32. The alloy powder is pressed in a magnetic field, preferably at a field strength of 1.8 T, to obtain a pressed body, the density of which is 4.3 g/cm ³ .

33. The press-formed body is placed in a sintering furnace and sintered at a sintering temperature of 1000° C. and a heat retention time of 6 hours to obtain a sintered magnet. The density of the sintered magnet is 7.56 g/ ^cm3 .

34. The surface of the sintered magnet is pickled to remove oil, and then sliced to obtain a base material C1 of 30 x 17 x 5 mm.

4. Sputtering is performed on the base material Sputtering is performed in a plating chamber, the target material is the first target material, and the base material C1 passes under the first target material to form the first plating layer on the surface of the base material. Form. The thickness of the first plating layer is 8 μm.

5. A diffusion treatment is performed on the sputtered base material C1, and after this process is kept at 800° C. for 18 hours, a tempering aging treatment is performed at 500° C. for 4 hours to obtain a rare earth diffused magnet.

Conduct magnetic performance tests and corrosion resistance tests on rare earth diffused magnets. Table 1 shows the performance of the rare earth diffused magnet of this example.

Base material sample 1 in Table 1 is a sample of base material C1 that has not undergone sputtering and diffusion treatment for the plating layer, and was manufactured after undergoing two-stage tempering and aging heat treatment. Among them, the tempering process is as follows: The primary tempering process is kept at 920°C for 2 hours, and the secondary tempering process is kept at 500°C for 4 hours.

Corrosion resistance test conditions: A sample is placed in a PCT aging test box, the conditions are set to 2 atm, 120°C, and 100% RH for 96 hours, and a corrosion resistance test is conducted.

Weight loss rate=(initial weight of sample−weight of sample after PCT experiment)/surface area of sample.

(Example 1-2)
This example is basically the same as Example 1 except that the sputtering target material is different, but the sputtering target material is Tb ₇₀ Nd ₂₅ Al ₅ , and the thickness of the plating layer is 8 μm.

(Example 1-3)
It is basically the same as Example 1 except that the sputtering target material is different, but the composition of the sputtering target material is Tb ₇₀ Nd ₂₅ Ga ₅ , and its sputtering thickness on the surface of the base material C1 is 8 μm.

(Example 1-4)
It is basically the same as Example 1 except that the sputtering target material is different, but the composition of the sputtering target material is Tb ₇₀ Nd ₂₅ Cu ₅ , and its sputtering thickness on the surface of the base material C1 is 8 μm.

(Example 1-5)
It is basically the same as Example 1 except that the sputtering target material is different, but the composition of the sputtering target material is Tb ₇₀ Nd ₂₅ Ag ₅ , and its sputtering thickness on the surface of the base material C1 is 8 μm.

(Example 1-6)
It is basically the same as Example 1 except that the sputtering target material is different, but the composition of the sputtering target material is Tb ₇₀ Nd ₂₂ Ce ₃ Al ₅ , and its sputtering on the surface of the base material C1 The thickness is 8 μm.

(Example 1-7)
It is basically the same as Example 1 except that the sputtering target material is different, but the composition of the sputtering target material is Tb ₇₀ Nd ₂₂ La ₃ Al ₅ , and its sputtering on the surface of the base material C1 The thickness is 8 μm.

(Comparative example 1)
This example is basically the same as Example 1 except that the sputtering target material is different. The sputtering target material was a pure metal Tb target, and the thickness of the Tb plating layer was 8 μm.

(Comparative example 2)
It is basically the same as Example 1 except that the sputtering target material is different, but the composition of the sputtering target material is Tb ₈₀ Nd ₁₅ Al ₅ , and its sputtering thickness on the surface of the base material C1 is 8 μm.

(Comparative example 3)
It is basically the same as Example 1 except that the sputtering target material is different, but the composition of the sputtering target material is Tb ₅₅ Nd ₄₀ Al ₅ , and its sputtering thickness on the surface of the base material C1 is 8 μm.

In Table 1, "Br" is residual magnetism, "Hcj" is intrinsic coercive force, (BH)max is maximum magnetic energy product, and "Hk/Hcj" is squareness.

As can be seen from the comparison, the rare earth diffused magnets manufactured in Examples 1-1 to 1-7, Comparative Example 1, Comparative Example 2, and Comparative Example 3 have significantly higher Hcj than base material sample 1. and Br decreased slightly. According to the corrosion resistance test results, the corrosion resistance of the rare earth diffused magnets of Examples 1-1 to 1-7 is higher than that of the rare earth diffused magnets produced in Comparative Example 1, Comparative Example 2, and Comparative Example 3. The corrosion resistance of Examples 1-1 to 1-7 is similar to that of base material sample 1. As can be seen, although the rare earth diffused magnets of Examples 1-1 to 1-7 were subjected to sputtering and diffusion treatment, their corrosion resistance did not deteriorate, whereas the rare earth diffused magnets of Comparative Examples 1, 2, and The corrosion resistance of rare earth diffused magnets was significantly reduced.

(Example 2)
The process is basically the same as that of Example 1, but differs in the following points.

The composition of the base material C2 of this example is Nd ₃₁ Dy _0.5 Co _1.2 Cu _0.16 Al _0.4 B _0.98 Fe _bal .

The composition of the first target material is Tb ₆₅ Pr ₂₅ Al ₁₀ .

The thickness of the sputtered first plating layer is 6 μm.

The diffusion treatment after sputtering included primary heat treatment: keeping warm at 1000°C for 2 hours, and secondary heat treatment: keeping warm at 600°C for 3 hours.

Table 2 shows the performance and corrosion resistance test results of the rare earth diffused magnet of Example 2.

Base material sample 2 in Table 2 is a sample of base material C2 without sputtering and diffusion treatment of the plating layer, and was prepared after undergoing two-stage tempering and aging heat treatment. This tempering process is as follows. The primary tempering process is kept at 1000°C for 2 hours, and the secondary tempering process is kept at 600°C for 3 hours.

(Example 3)
It is basically the same as Example 2 except that the sputtering target material is different, but the composition of the sputtering target material is Dy ₆₅ Pr ₂₅ Sn ₁₀ , and its sputtering thickness on the surface of the base material C2 is 6 μm.

(Example 4)
It is basically the same as Example 2 except that the sputtering target material is different, but the composition of the sputtering target material is Dy ₃₅ Tb ₂₅ Pr ₂₅ Cu ₁₅ , and its sputtering on the surface of the base material C2 The thickness is 6 μm.

(Example 5)
It is basically the same as Example 2 except that the sputtering target material is different, and the composition of the sputtering target material is Tb ₆₀ Ho ₈ Pr ₂₂ Al ₁₀ , and its sputtering thickness on the surface of the base material C2 is The diameter is 6 μm.

(Example 6)
It is basically the same as Example 2 except that the sputtering target material is different, and the composition of the sputtering target material is Tb ₆₆ Pr ₂₀ Y ₂ Co ₁₂ . The sputtering thickness is 6 μm.

(Example 7)
It is basically the same as Example 2 except that the sputtering target material is different, and the composition of the sputtering target material is Tb ₆₃ Pr ₂₇ Al ₁₀ , and its sputtering thickness on the surface of the base material C2 is It is 6 μm.

From Table 2, it can be seen that the corrosion resistance of the rare earth diffused magnet of the present invention was slightly changed compared to the base material. After sputtering with the target material of the present invention, the corrosion resistance of the prepared rare earth diffused magnet is significantly improved. According to actual needs, the thickness of the first plating layer can be reduced to 2 μm.

(Examples 8 to 15)
Using base material C2, the composition is Nd ₃₁ Dy _0.5 Co _1.2 Cu _0.16 Al _0.4 B _0.98 Fe _bal .

The manufacturing process for the base material C2 is the same as in Example 1. The manufacturing process of the first target material and the second target material is the same as the manufacturing process of the first target material in Example 1.

When sputtering the base material C2, first, a first target material is sputtered to form a first plating layer on the surface of the base material C2, and then a second target material is sputtered to form a second plating layer. is formed on the surface of the first plating layer. The thicknesses of the first plating layer and the second plating layer are shown in Table 3.

The base material C2 after being sputtered is subjected to a diffusion treatment. The diffusion treatment included a primary heat treatment: incubation at 920°C for 6 hours, and a secondary heat treatment: incubation at 450°C for 8 hours.

Table 3 shows the composition, magnetic properties, and corrosion resistance test results of the plating layers of Examples 8 to 15.

Base material sample 3 in Table 3 is a sample of base material C2 without sputtering and diffusion treatment of the plating layer, and was manufactured after undergoing two-stage tempering and aging heat treatment. This tempering process is as follows. The primary tempering process is kept at 920°C for 4 hours, and the secondary tempering process is kept at 450°C for 8 hours.

Salt spray test: The test sample was placed in a salt spray test box to undergo corrosion in a continuous spray environment. The liquid of the spray solution is a 5% NaCl solution, pH=7.1, and the temperature is 25° C. The samples are observed every 24 hours for rust spots.

High-temperature and high-pressure experiment: put the test sample into a high-temperature and high-pressure experiment box, the experiment temperature is 120 ± 3 ° C, the vapor pressure is 0.20 MPa, the experiment is carried out for 288 hours, and then the sample is taken out and ultrasonic cleaning is used to investigate the corrosion generation. Remove the object and record the difference in weight before and after corrosion. Finally, the weight loss per unit surface area is calculated as the substrate weight loss parameter by dividing the weight loss by the surface area of the sample.

Compared with the rare earth diffused magnet in which only the first plating layer was sputtered, the time of the salt water spray resistance test of the rare earth diffused magnet increased after the second plating layer was sputtered, and the weight loss rate in the weight loss test decreased. , its corrosion resistance is further improved. At the same time, the magnet with the second plating layer sputtered had slightly improved Hcj than the magnet with only the first plating layer sputtered.

The various embodiments described above with reference to the accompanying drawings are merely for explaining the present invention, and do not limit the scope of the present invention. Those skilled in the art should understand that all modifications or equivalent substitutions made to the present invention without departing from the spirit and scope of the invention are to be included within the scope of the invention. Further, unless the context dictates otherwise, words appearing in the singular include the plural and vice versa. Further, unless otherwise specified, all or a portion of any embodiment may be used in combination with all or a portion of any other embodiment.

Claims (9)

Step A. A first target material is sputtered onto a base material to form a first plating layer on the surface of the base material, and the composition of the first target material is RH _x -RL _y -M _z in mass percent, provided that: RH is one or more of Dy, Tb, or Ho, RH includes at least one of Dy or Tb, RL is one or more of Nd, Pr, Ce, La, and Y, and RL is Nd or M is at least one element of Co, Cu, Ga, Ag, Sn or Al, y is 25 to 28 wt%, z is 0 to 20 wt%, and x is ( 100-y-z) wt%, and the substrate is a sintered NdFeB magnet;
Step B. A method for manufacturing a rare earth diffused magnet, comprising the step of performing a diffusion treatment on a sputtered base material to obtain a rare earth diffused magnet. The method for manufacturing a rare earth diffused magnet according to claim 1, wherein z is 0 to 12 wt%. The method for manufacturing a rare earth diffused magnet according to claim 1, wherein the first plating layer has a thickness of 2 to 20 μm. In step A, after sputtering a first target material, a second target material is sputtered to form a second plating layer on the first plating layer, and the second target material has a composition of Cr, Ti, The method for manufacturing a rare earth diffused magnet according to claim 1, characterized in that the magnet is at least one of W, Mo, Si, _{Al2O3 ,} or _ZrO2 . 5. The method for manufacturing a rare earth diffused magnet according to claim 4, wherein the second plating layer has a thickness of 0.1 to 6 μm. Before said step A, the manufacturing of said substrate further comprises: producing alloy flakes by melting and rapid solidification of raw materials;
performing hydrogen crushing and jet milling on the alloy flakes to obtain alloy powder;
pressing the alloy powder in a magnetic field to obtain a press molded body;
Claim 1 characterized by comprising: placing the press molded body in a sintering furnace and sintering it to obtain a sintered magnet; and slicing the sintered magnet to obtain the base material. A method for manufacturing a rare earth diffused magnet described in . The method for manufacturing a rare earth diffused magnet according to claim 6, wherein the thickness of the alloy flakes is 0.15 to 0.5 mm. The method for manufacturing a rare earth diffused magnet according to claim 6, wherein the thickness of the base material is 1 to 10 mm. The method for manufacturing a rare earth diffused magnet according to claim 1, wherein the diffusion treatment includes the following primary heat treatment and secondary heat treatment.
Primary heat treatment: Insulation at 800-1000℃ for 2-18 hours Secondary heat treatment: Insulation at 450-600℃ for 3-8 hours

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