Manufacturing method for RTB-type sintered magnets

Abstract

This method can reduce or suppress the adhesion of fine powder to components that may come into contact with the fine powder between the grinding process and the molding process. [Solution] The method for manufacturing an RTB-type sintered magnet according to the present disclosure includes a fine grinding step to obtain fine powder by fine grinding an RTB-type sintered magnet alloy (where R is a rare earth element and always contains at least one selected from the group consisting of Nd, Pr and Ce, T is at least one transition metal and always contains Fe, and B is boron), and a molding step to mold the fine powder using a powder press molding apparatus. At least the surface portion of the member that comes into contact with the fine powder between the fine grinding step and the molding step is formed from aluminum.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing an R-T-B sintered magnet.

Background Art

[0002] An R-T-B sintered magnet (where R is a rare earth element, necessarily including at least one selected from the group consisting of Nd, Pr, and Ce, T is at least one transition metal necessarily including Fe, and B is boron) consists of a main phase of a compound having an R2Fe 14 B-type crystal structure, a grain boundary phase located at the grain boundary portion of this main phase, and a compound phase generated by the influence of trace additive elements and impurities. The R-T-B sintered magnet has a high residual magnetic flux density B r (hereinafter, may be simply referred to as "B r ") and a high coercive force H cJ (hereinafter, may be simply referred to as "H cJ ") and exhibits excellent magnetic properties, and is thus known as the highest-performance magnet among permanent magnets. For this reason, R-T-B sintered magnets are used in various motors in the automotive field such as electric vehicles (EV, HV, PHV), the renewable energy field such as wind power generation, the home appliance field, and the industrial field.

[0003] Rare earth-based R-T-B sintered magnets such as R-T-B sintered magnets are manufactured through a process of preparing an alloy for the R-T-B sintered magnet, a process of finely pulverizing the alloy to produce fine powder, a process of press-forming the fine powder to produce a powder compact, and a process of sintering the powder compact. The fine powder of the alloy is produced, for example, by the following method.

[0004] First, a raw material alloy is produced from the molten metal of various raw material metals by a method such as the strip casting method. The obtained raw material alloy is subjected to a pulverization process to obtain raw material alloy powder having a predetermined particle size distribution. This pulverization process usually includes a coarse pulverization process and a fine pulverization process. The former is performed, for example, by a "hydrogen pulverization process" that utilizes the phenomenon of hydrogen embrittlement. The latter is performed, for example, using an air-flow pulverizer (jet mill).

[0005] Fine powder formed by pulverizing devices such as jet mills is composed of active particles on its surface. Therefore, if it comes into contact with the inner walls of the pulverizing device and piping immediately after pulverization, it can adhere to the piping, causing blockages and reducing the recovery rate of the fine powder.

[0006] Patent Document 1 attempts to solve this problem by flowing an oxygen-containing gas through the grinding apparatus.

[0007] Patent Document 2 discloses that, in order to solve the above problems, the surface of the part that comes into contact with the fine powder inside the grinding device is formed from high-purity alumina or silicon nitride. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2006-176839 [Patent Document 2] Japanese Patent Publication No. 2004-337742 [Overview of the project] [Problems that the invention aims to solve]

[0009] The fine powder formed by the grinding device may come into contact with transport containers, hoppers, screw conveyors, feeders, and scraping devices between the grinding process and the molding process. The problem of the fine powder adhering to these devices is not solved by the technologies described in Patent Documents 1 and 2.

[0010] The manufacturing method for RTB-type sintered magnets of this disclosure makes it possible to reduce the adhesion of fine powder to components that may come into contact with the fine powder between the fine grinding step and the molding step. [Means for solving the problem]

[0011] In exemplary and non-limiting embodiments, the method for manufacturing an RTB-type sintered magnet of the present disclosure includes a grinding step of grinding an RTB-type sintered magnet alloy (where R is a rare earth element and always contains at least one selected from the group consisting of Nd, Pr, and Ce, T is at least one transition metal and always contains Fe, and B is boron) to obtain fine powder, and a molding step of molding the fine powder with a powder press molding apparatus, wherein at least the surface portion of the member that comes into contact with the fine powder between the grinding step and the molding step is formed of aluminum. [Effects of the Invention]

[0012] According to embodiments of this disclosure, it is possible to reduce or suppress the adhesion of fine powder to components that may come into contact with the fine powder between the grinding process and the molding process. [Brief explanation of the drawing]

[0013] [Figure 1] This flowchart outlines the manufacturing method of an RTB-type sintered magnet according to an embodiment of the present disclosure. [Figure 2] This diagram schematically illustrates an example of the configuration and operation of a vibrating feeder, weighing cup, raw material cup, funnel, chute, feeder box, and powder press molding machine. [Figure 3] This is a schematic cross-sectional view showing a part of a component having a stainless steel substrate and an aluminum coating layer covering at least a portion of the surface of the stainless steel substrate. [Figure 4] This is a schematic cross-sectional view showing a portion of a component that is a machined aluminum part. [Figure 5] This is a schematic cross-sectional view showing a portion of another component that is a machined aluminum part. [Figure 6] This is a schematic perspective view showing an example of a weighing cup configuration. [Figure 7] This figure schematically shows an example of the configuration of the grinding system in this embodiment. [Modes for carrying out the invention]

[0014] Hereinafter, embodiments of a method for manufacturing an R-T-B sintered magnet in the present disclosure will be described. Here, R is a rare earth element and necessarily includes at least one selected from the group consisting of Nd, Pr, and Ce. T is at least one of transition metals and necessarily includes Fe. B is boron.

[0015] <Embodiment> First, while referring to FIG. 1, an outline of the method for manufacturing an R-T-B sintered magnet of the present embodiment will be described. As shown in FIG. 1, the method for manufacturing an R-T-B sintered magnet in the present embodiment includes a fine pulverization step (S10) of finely pulverizing an alloy for an R-T-B sintered magnet to obtain fine powder, and a molding step (S20) of molding the fine powder by a powder press molding apparatus.

[0016] Further, at least the surface layer portion of a member with which the fine powder comes into contact between the fine pulverization step (S10) and the molding step (S20) is formed of aluminum. The member with which the fine powder comes into contact between the fine pulverization step (S10) and the molding step (S20) can be, for example, a container for transporting the fine powder or a part of a powder supply apparatus that supplies the fine powder to a powder press molding apparatus. In the case of the container, the surface layer portion formed of aluminum does not need to extend over the entire surface of the container, and it is sufficient if it forms the inner wall surface of the container. The powder supply apparatus is, for example, at least one of a hopper, a screw conveyor, a feeder, and a scraping device. Also in such a powder supply apparatus, it is sufficient if at least the surface layer portion of a portion with which the fine powder can come into contact is formed of aluminum.

[0017] Figure 2 schematically shows an example of the configuration and operation of a vibrating feeder 10, a weighing cup 12, a raw material cup 14, a funnel 16, a chute 18, a feeder box 20, and a powder press molding apparatus 30. The vibrating feeder 10 receives the fine powder after the fine pulverization process from the fine pulverization apparatus, and vibrates in a state where the fine powder is placed thereon, thereby dropping the fine powder into the weighing cup 12 (Fig. 2(a)). The weight of the fine powder accumulated in the weighing cup 12 is accurately measured by a weighing scale or the like. When the weight of the fine powder accumulated in the weighing cup 12 reaches a predetermined value, the weighing cup 12 rotates as shown in Fig. 2(b), and moves the predetermined weight of fine powder stored in the weighing cup 12 to the raw material cup 14. Thereafter, as shown in Fig. 2(c), the raw material cup 14 rotates, and the fine powder is accommodated in the feeder box 20 through the funnel and the chute 18. The feeder box 20 moves on the powder press molding apparatus 30 and operates to supply the fine powder into the die cavity 30A provided in the powder press apparatus.

[0018] In the above-described example of the configuration and operation, each of the vibrating feeder 10, the weighing cup 12, the raw material cup 14, the funnel 16, the chute 18, and the feeder box 20 can be a member with which the fine powder comes into contact between the fine pulverization process (S10) and the molding process (S20).

[0019] According to the experiments of the present inventor, it was found that when these members are formed of, for example, stainless steel, even if the surface thereof is smooth, the fine powder adheres to the surface of each member. In particular, when the fine powder adheres to the weighing cup 12, a part of the accurately weighed fine powder remains inside the weighing cup 12, so that the required amount of fine powder is not supplied to the die cavity 30A of the powder press molding apparatus 30, and a problem may occur that the powder molded body does not have sufficient weight and density. This may reduce the production yield of the final sintered magnet.

[0020] The inventors tested whether coating the surface of a component made of stainless steel with various materials could reduce or suppress the adhesion of fine powder. They found that when using organic materials such as fluororesins with excellent lubricity and release properties, or composite materials of inorganic materials such as ceramics and organic materials such as fluororesins, as coating materials, the adhesion of fine powder could not be sufficiently improved. However, they found that when aluminum was used as the coating material, the adhesion of fine powder hardly occurred. The thickness of the aluminum coating layer is, for example, 0.2 μm to 50 μm, preferably 0.5 μm to 20 μm.

[0021] Furthermore, it is sufficient that at least the surface portion of the component that comes into contact with the fine powder between the crushing and molding processes is made of aluminum; the portion other than the surface may be made of another material, such as stainless steel. Stainless steel is easy to process and has been widely used in conventional materials that come into contact with fine powder. Therefore, the effects of the present invention can be obtained by using a conventionally used stainless steel component as a stainless steel substrate and forming an aluminum coating layer to cover the portion of the surface of the stainless steel substrate that comes into contact with the fine powder. The aluminum coating layer can be formed using various film formation techniques such as electroplating, vapor deposition, sputtering, and ion plating. In addition, the component that can come into contact with the fine powder may itself be a machined aluminum part.

[0022] A native oxide film less than 10 nm thick is formed on the surface of aluminum in the atmosphere. This native oxide film is a layer of aluminum oxide (alumina) that spreads across the surface of the aluminum. Typically, an aluminum oxide layer is also formed on the surface of the surface layer formed from aluminum in the disclosure. The presence of such an aluminum oxide layer may contribute to the function of reducing or suppressing the adhesion of fine powder, but the mechanism by which the adhesion of fine powder to aluminum is reduced or suppressed is unknown. It should be noted that the aluminum oxide layer does not necessarily have to be a native oxide film; it may also be an anodized film intentionally formed by anodic oxidation.

[0023] As explained above, "formed from aluminum" includes aluminum coatings, machined aluminum, natural oxide films of aluminum, and anodized films, but does not include those formed from high-purity alumina or silicon nitride as described in the prior art. This can also be expressed as "made from metallic aluminum."

[0024] Figure 3 is a schematic cross-sectional view of a part of a component having a stainless steel substrate 50 and an aluminum coating layer 52 (thickness: for example, 0.5 μm to 50 μm) covering at least a portion of the surface of the stainless steel substrate 50. A native oxide film 52A (thickness: for example, 1 nm to 5 nm) is formed on the surface of the aluminum coating layer 52.

[0025] Figure 4 is a schematic cross-sectional view showing a part of a component that is a machined aluminum part 56. In the component shown in Figure 4, a native oxide film 52A (thickness: for example, 1 nm to 5 nm) is formed on the surface of the machined aluminum part 56.

[0026] Figure 5 is a schematic cross-sectional view showing a part of another component, which is a machined aluminum part 56. In the component shown in Figure 5, an anodized film 52B (thickness: for example, 5 μm to 100 μm) formed by anodizing is formed on the surface of the aluminum coating layer 52.

[0027] In the cross-sections of the members illustrated in Figures 3 to 5, the surfaces of the aluminum coating layer 52 and the machined aluminum parts 56 are smooth, but curved surfaces may be formed on these surfaces. Fine irregularities may be formed on these surfaces through repeated contact with fine powder, and it has been found that the presence of such irregularities contributes to reducing the adhesion of fine powder.

[0028] Figure 6 is a schematic perspective view showing an example of the configuration of a weighing cup 12. For reference, Figure 6 shows the X, Y, and Z axes, which are orthogonal to each other. The Z axis is parallel to the vertical direction. The weighing cup 12 is one of the containers for transporting fine powder. In this example, a surface layer 12A made of aluminum is provided on the inner wall surface of the weighing cup (container) 12. More specifically, the weighing cup 12 in this example has a cup-shaped stainless steel base material 12B and an aluminum coating layer (a surface layer 12A made of aluminum) that covers at least a part (the inner wall surface) of the surface of the stainless steel base material 12B.

[0029] In this example, the stainless steel base material 12B has a cup shape that is roughly similar to a "frustum of a square pyramid," with at least one side being inclined. By adopting this shape, in this weighing cup 12, the fine powder is in contact with the aluminum coating layer (the surface layer portion 12A formed from aluminum) rather than the stainless steel base material 12B, and therefore the entire amount is supplied to another container located below (for example, the raw material cup 14 in Figure 2) without adhering to the inner wall surface of the weighing cup 12. As a result, weight variation of the molded powder is reduced, and the resulting sintered magnets are less likely to be defective.

[0030] The following describes examples of each process shown in Figure 1.

[0031] <Fine grinding process (S10)> In this embodiment, the fine grinding step (S10) to obtain fine powder by finely grinding the RTB-type sintered magnet alloy is performed by producing rare earth alloy powder using a jet mill grinding device. Prior to the fine grinding step (S10), it is preferable to perform a hydrogen grinding step to produce coarse powder of the rare earth alloy. Here, the composition of the rare earth raw material alloy is, for example, as follows. R: 26.5~33.5% by mass (R is a rare earth element and must contain at least one of Nd and Pr), M: 0.20~1.50 mass% (M is at least one element selected from the group consisting of Ga, Cu, Zn, Al, and Si, and must include Cu), B: 0.85~0.92% by mass, T: Contains 61.5% by mass or more (T is Fe and Co, and Fe accounts for 90% or more of T by mass ratio), Tb: 0.30% by mass or less, Dy: 0.30% by mass or less

[0032] Rare earth alloys having the above composition can be produced, for example, by the strip casting method. Rare earth alloys may contain multiple types of alloying components with different compositions.

[0033] The hydrogen pulverization process may include a hydrogen absorption step in which hydrogen is absorbed into the rare earth alloy at a temperature of 200°C or less in a processing chamber, and a dehydrogenation step in which hydrogen is exhausted from the processing chamber and the rare earth alloy is heated to a temperature of, for example, 80°C to 650°C to produce a coarse pulverized powder.

[0034] The average particle size of the coarsely ground powder is, for example, 10 μm to 500 μm. In this disclosure, the average particle size (d50) can be measured by airflow-dispersive laser diffraction (in accordance with JIS Z 8825:2013 revised edition). That is, in this specification, the average particle size means the particle size (median diameter: d50) at which the cumulative particle size distribution (volume basis) from the small particle size side accounts for 50%.

[0035] In the fine grinding step (S10), the coarsely ground powder is ground to obtain fine powder with a median diameter d50 of, for example, 3.5 μm or less. The fine grinding step (S10) may also include a step of mixing an organic grinding aid with the coarsely ground powder. An example of an organic grinding aid is zinc stearate. The average particle size d50 of the fine powder is preferably 2.0 μm or more and 3.5 μm or less.

[0036] Next, an example of a grinding system used in this embodiment will be described with reference to Figure 7. Figure 7 is a schematic diagram showing an example of the configuration of the grinding system 1000 in this embodiment. In this example, the grinding system 1000 includes a jet mill grinding device 100, a cyclone collection device 200, a bag filter device 300, and a recovery container 400.

[0037] The jet mill grinding device 100 receives the material to be ground from a raw material tank (not shown) via a raw material input pipe 34. Multiple valves are provided in the raw material input pipe 21, and the internal pressure of the jet mill grinding device 100 is appropriately maintained by opening and closing these valves. The material to be ground introduced into the jet mill grinding device 100 is finely ground by collisions between the material itself and with impact plates installed to efficiently advance the grinding process, due to the high-speed injection of inert gas from the nozzle pipe 31.

[0038] Rare earth alloy powders, such as RTB-type sintered magnet alloys, are active and easily oxidized. Therefore, to avoid the risk of heat generation and ignition, and to improve the performance of the magnets by reducing the oxygen content as an impurity, dry (high-purity) inert gases such as nitrogen, argon, and helium with a dew point of -60°C dp or lower are generally used as the gas in the jet mill grinding device 100.

[0039] The finely ground powder particles (fine powder) inside the jet mill grinding device 100 are carried by the rising airflow and guided from the upper outlet to the inlet pipe 22 of the cyclone collection device 200. Coarse particles that have not been sufficiently ground may be separated by a classification rotor, for example, installed to classify coarse particles larger than the median diameter (d50), and remain inside the jet mill grinding device 100, where they may undergo a further crushing process by impact. Such classification of coarse particles may be performed using centrifugal separation with a swirling flow instead of using a classification rotor. In this way, the coarsely ground powder introduced into the jet mill grinding device 100 is ground into fine powder with an average particle size distribution (median diameter: d50) of, for example, 2.0 μm to 4.5 μm, before being moved to the cyclone collection device 200.

[0040] The cyclone collection device 200 is used to separate the powder from the airflow carrying the powder. Specifically, coarsely ground powder of RTB-type sintered magnet alloy is ground in the preceding jet mill, and the fine powder generated by the grinding is supplied to the cyclone collection device 200 through the inlet pipe 22 along with the gas used for grinding. The mixture of the inert gas (grinding gas) and the ground fine powder is sent to the cyclone collection device 200 in a high-speed airflow. The cyclone collection device 200 is used to separate these grinding gases from the fine powder. The fine powder separated from the grinding gas is collected in a recovery container (recovery device) 400 via piping 24 connected to the discharge port 40.

[0041] The pulverized gas is supplied to the bag filter device 300 via the outlet pipe 23 of the cyclone collection device 200. In the bag filter device 300, very small particles are collected, and the clean gas is released to the outside from the exhaust port 25. Although it is possible to use a bag filter instead of the cyclone collection device 200 for this solid-gas separation, the scattering of fine powder into the atmosphere due to filter damage has a significant impact on the environment and safety. Therefore, as shown in the example in Figure 3, it is desirable to further separate the fine particles from the gas separated by the cyclone collection device 200 by using a bag filter in combination.

[0042] In the grinding system 1000 shown in Figure 3, a pipe 24 for transferring the fine powder produced by the jet mill grinding device 100 to the recovery container 400 is provided in the cyclone collection device 200. If the cyclone collection device 200 is not present, such a pipe 24 can be provided directly in the jet mill grinding device 100. Inert gas can be supplied from the active gas supply unit to the inside of the pipe 24 and the inside of the recovery container 400, filling them with inert gas.

[0043] By using the grinding system 1000 having the above configuration, it becomes possible to transfer the fine powder produced by the jet mill grinding device 100 to the recovery container 400. The recovery container 400 may be configured to be detachable from the grinding system 1000.

[0044] <Molding process (S20) in which fine powder is molded using a powder press molding device> The fine powder collected in the collection container 400 is supplied to the powder press molding apparatus using the components shown in Figure 2, as described above, and the molding process is carried out. The fine powder is compressed and molded by the powder press molding apparatus to produce a powder molded body.

[0045] Powder molded bodies can be manufactured, for example, by magnetic field pressing. In magnetic field pressing, powder molded bodies can be formed by pressing in an inert gas atmosphere or by wet pressing, from the viewpoint of suppressing oxidation. In wet pressing, the surface of the particles constituting the powder molded body is coated with a dispersant such as an oil, suppressing contact with oxygen and water vapor in the atmosphere. Therefore, oxidation of the particles by the atmosphere before, during, or after the pressing process can be prevented or suppressed.

[0046] <Other processes> Next, a sintering process is performed to sinter the powder molded body, thereby obtaining a rare earth sintered magnet (sintered body).

[0047] The sintering of the powder-molded body is preferably carried out at a temperature in the range of 1000°C to 1150°C. To prevent oxidation due to sintering, residual gases in the atmosphere may be replaced with inert gases such as helium or argon. It is preferable to heat treat the obtained sintered body. Heat treatment can improve the magnetic properties. Known conditions can be used for heat treatment, such as heat treatment temperature and heat treatment time. The rare earth sintered magnet body thus obtained is subjected to grinding and polishing, surface treatment, and magnetization processes as needed to complete the final rare earth sintered magnet. [Examples]

[0048] The present disclosure will be explained in more detail below with experimental examples, but the present disclosure is not limited to those examples.

[0049] The RTB-type sintered magnet alloy was prepared for fine grinding using the method described in the above embodiment. Furthermore, examples and comparative examples of weighing cups having the shape shown in Figure 6 were prepared. • Example: Aluminum coating on the inner wall surface of a stainless steel cup • Comparison example: Stainless steel cup (uncoated)

[0050] After supplying 24g of finely ground RTB-type sintered magnet alloy powder to the weighing cups of the example and comparative example, the weighing cups were rotated approximately 90° counterclockwise around an axis parallel to the Y-axis in Figure 6. The fine powder accumulated inside the weighing cup 12 was discharged downwards and transferred to the raw material cup 14, and then fed into the feeder box 20 through the funnel 16 and chute 18. After repeating this eight times, the fine powder was supplied into the die cavity 30A of the powder press molding apparatus 30 to produce powder molded bodies. The weight of approximately 400 powder molded bodies thus produced was measured, and the weight variation (coefficient of variation CV) of the powder molded bodies was calculated by dividing the standard deviation σ by the average weight of the powder molded bodies. Table 1 shows the weight variation of the powder molded bodies in the comparative example and example. From these results, it can be seen that the variation in measured values ​​such as weight is lower in the example than in the comparative example. In the comparative example, fine powder was observed adhering to the inner wall surface of the weighing cup, but no such adhesion was observed in the example.

[0051] [Table 1]

[0052] This experiment demonstrates that aluminum has the effect of making it difficult for fine powder to adhere to RTB-type sintered magnet alloys, even when in contact with them.

[0053] As described above, this disclosure includes a method for manufacturing RTB-type sintered magnets as described in the following sections. [Item 1] A fine grinding step to obtain fine powder by finely grinding an RTB-type sintered magnet alloy (where R is a rare earth element and must contain at least one selected from the group consisting of Nd, Pr, and Ce; T is at least one transition metal and must contain Fe; and B is boron), A molding step in which the aforementioned fine powder is molded using a powder press molding device, Includes, A method for manufacturing an RTB-type sintered magnet, wherein at least the surface portion of the member that comes into contact with the fine powder between the fine grinding step and the molding step is made of aluminum. [Item 2] The method for manufacturing an RTB-type sintered magnet according to item 1, wherein the member comprises a stainless steel substrate and an aluminum coating layer covering at least a portion of the surface of the stainless steel substrate. [Item 3] The aforementioned component is a machined aluminum part, according to the method for manufacturing an RTB-type sintered magnet as described in item 1. [Item 4] The aforementioned member is a container for transporting the fine powder, A method for manufacturing an RTB-type sintered magnet according to any one of items 1 to 3, wherein the surface portion formed from aluminum forms the inner wall surface of the container. [Item 5] The method for manufacturing an RTB-type sintered magnet according to any one of items 1 to 3, wherein the member is part of a powder supply device that supplies the fine powder to the powder press molding device. [Item 6] The method for manufacturing an RTB-type sintered magnet according to item 5, wherein the powder supply device is at least one of a hopper, a screw conveyor, a feeder, and a scraping device. [Item 7] A method for manufacturing an RTB-type sintered magnet according to any one of items 1 to 6, wherein an aluminum oxide layer is formed on the surface of the surface portion formed from aluminum. [Item 8] The method for manufacturing an RTB-type sintered magnet as described in item 7, wherein the aluminum oxide layer is a native oxide film. [Item 9] The method for manufacturing an RTB-type sintered magnet as described in item 7, wherein the aluminum oxide layer is an anodized film. [Explanation of Symbols]

[0054] 10. Vibration Feeder 12 weighing cups 14 ingredient cups 16 Funnel 18 shots 20 Feeder Boxes 30 Powder press molding machine 100 Jet Mill Grinding Equipment 200 Cyclone collection device 300 Bag Filter System 400 collection containers

Claims

1. A fine grinding step to obtain fine powder by finely grinding an R-T-B sintered magnet alloy (where R is a rare earth element and must contain at least one selected from the group consisting of Nd, Pr, and Ce; T is at least one transition metal and must contain Fe; and B is boron), A molding step in which the aforementioned fine powder is molded using a powder press molding device, Includes, A method for manufacturing an R-T-B type sintered magnet, wherein at least the surface portion of a member that comes into contact with the fine powder between the fine grinding step and the molding step is made of aluminum.

2. The method for manufacturing an R-T-B sintered magnet according to claim 1, wherein the member comprises a stainless steel substrate and an aluminum coating layer covering at least a portion of the surface of the stainless steel substrate.

3. The method for manufacturing an R-T-B type sintered magnet according to claim 1, wherein the aforementioned member is a machined aluminum part.

4. The aforementioned member is a container for transporting the fine powder, The method for manufacturing an R-T-B sintered magnet according to any one of claims 1 to 3, wherein the surface portion formed from aluminum forms the inner wall surface of the container.

5. The method for manufacturing an R-T-B sintered magnet according to any one of claims 1 to 3, wherein the member is part of a powder supply device that supplies the fine powder to the powder press molding device.

6. The method for manufacturing an R-T-B sintered magnet according to claim 5, wherein the powder supply device is at least one of a hopper, a screw conveyor, a feeder, and a scraping device.

7. A method for manufacturing an R-T-B sintered magnet according to any one of claims 1 to 3, wherein an aluminum oxide layer is formed on the surface of the surface portion formed from aluminum.

8. The method for manufacturing an R-T-B type sintered magnet according to claim 7, wherein the aluminum oxide layer is a native oxide film.

9. The method for manufacturing an R-T-B type sintered magnet according to claim 7, wherein the aluminum oxide layer is an anodized film.

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