Permanent magnet comprising pr as grain boundary diffusion material and manufacturing method therefor

Abstract

Provided are a permanent magnet comprising Pr as a grain boundary diffusion material and a manufacturing method therefor. The permanent magnet comprising Pr as a grain boundary diffusion material comprises: a plurality of crystal grains containing a main phase of Nd-Fe-B; and a coercivity reinforcing layer disposed between the plurality of crystal grains, wherein the coercivity reinforcing layer contains Pr, Ga, and Cu, the mass ratio of the Ga is 0.1 wt% to 0.4 wt%, and the mass ratio of the Cu is 0.1 wt% to 0.4 wt%.

Description

Permanent magnet containing PR as a grain boundary diffusion material and method for manufacturing the same

[0001] The present invention relates to a permanent magnet and a method for manufacturing the same, and more specifically, to a permanent magnet with improved magnetic properties by including Pr as a grain boundary diffusion material and a method for manufacturing the same.

[0002] NdFeB magnets are Nd2Fe, a compound of the rare earth elements neodymium (Nd), iron (Fe), and boron (B). 14 It is a permanent magnet with a composition of B, and is widely used across various industrial fields such as electric vehicles, wind turbines, and home appliances.

[0003] NdFeB-based magnets require high coercivity to ensure reliability at high temperatures. Among the methods to improve coercivity, grain boundary diffusion technology has been proposed to increase coercivity by diffusing heavy rare earth elements along the grain boundaries of magnetic powder. Generally, heavy rare earth elements such as dysprosium (Dy) or terbium (Tb) are mainly used, but these elements have the disadvantage of being scarce in the Earth's crust and expensive.

[0004] Recently, grain boundary diffusion technology using praseodymium (Pr), a rare earth element, as the main element is being researched, instead of heavy rare earth elements which have high price volatility and environmental risks. When using Pr-based metals for grain boundary diffusion, the selection of the base material is also very important. This is because the composition, purity, and crystal structure of the base material directly affect the efficiency of grain boundary diffusion and the characteristics of the final magnet.

[0005] The technical problem that the present invention aims to solve is to provide a permanent magnet with improved magnetic properties by including Pr as a grain boundary diffusion material, a method for manufacturing the same, and a base material for grain boundary diffusion.

[0006] The technical problems of the present invention are not limited to those mentioned above, and other unmentioned technical problems will be clearly understood by those skilled in the art from the description below.

[0007] A permanent magnet containing Pr as a grain boundary diffusion material for solving the aforementioned technical problem comprises a plurality of crystal grains comprising a columnar phase of Nd-Fe-B; and a coercivity reinforcing layer disposed between the plurality of crystal grains, wherein the coercivity reinforcing layer comprises Pr, Ga, and Cu, the mass ratio of Ga is 0.1 wt% to 0.4 wt%, and the mass ratio of Cu is 0.1 wt% to 0.4 wt%.

[0008] In some embodiments of the present invention, the mass ratio of the grain boundary diffusion material in the plurality of crystal grains and the coercivity reinforcing layer may be 1.5 to 10 wt%.

[0009] In some embodiments of the present invention, the mass ratio of the grain boundary diffusion material in the plurality of crystal grains and the coercivity reinforcing layer is 2 to 10 wt%, and the coercivity of the permanent magnet may be 20 kOe or more.

[0010] In some embodiments of the present invention, the mass ratio of the grain boundary diffusion material in the plurality of crystal grains and the coercivity reinforcing layer is 2 to 10 wt%, and the coercivity of the permanent magnet may be 25 kOe or more.

[0011] In some embodiments of the present invention, the grain boundary diffusion material included in the plurality of crystal grains and the coercivity reinforcing layer may contain 0.5 to 4 wt% silver.

[0012] In some embodiments of the present invention, the residual magnetic flux density of the permanent magnet may be 14.5 kG or more.

[0013] A method for manufacturing a permanent magnet containing Pr as a grain boundary diffusion material to solve the above-described technical problem comprises the steps of providing a base material, applying a grain boundary diffusion material to the base material, and heating the applied grain boundary diffusion material and the base material to form a permanent magnet, wherein the permanent magnet comprises a plurality of crystal grains including a columnar phase of Nd-Fe-B and a coercivity reinforcing layer disposed between the plurality of crystal grains, wherein the coercivity reinforcing layer comprises Pr, Ga, and Cu, the mass ratio of Ga is 0.1 wt% to 0.4 wt%, and the mass ratio of Cu is 0.1 wt% to 0.4 wt%.

[0014] In some embodiments of the present invention, the base material may contain at least 1 wt% of Pr.

[0015] In some embodiments of the present invention, the step of applying a grain boundary diffusion material to the base material may include applying 1 wt% to 8 wt% of the grain boundary diffusion material to the base material.

[0016] In some embodiments of the present invention, the step of applying a grain boundary diffusion material to the base material includes applying 2 wt% to 8 wt% of the grain boundary diffusion material to the base material, and the coercivity of the permanent magnet may be 20 kOe or more.

[0017] In some embodiments of the present invention, the step of applying a grain boundary diffusion material to the base material includes applying 4 wt% to 8 wt% of the grain boundary diffusion material to the base material, and the coercivity of the permanent magnet may be 25 kOe or more.

[0018] Specific details of other embodiments are included in the detailed description and drawings.

[0019] A permanent magnet containing Pr as a grain boundary diffusion material according to an embodiment of the present invention may have enhanced coercivity by including Pr as a grain boundary diffusion material, and may be advantageous for the production environment of permanent magnet products because it does not use heavy rare earth elements such as Dy or Tb.

[0020] In addition, the permanent magnet according to the embodiment of the present invention can have an improved crystal grain structure and a structure of a coercivity reinforcing layer by performing a grain boundary diffusion process using a base material containing 1 wt% or more of Pr, which can provide improved coercivity for a permanent magnet capable of operating in a high-temperature environment. Meanwhile, even when using a base material that does not contain 1 wt% or more of Pr, an effect of improving coercivity can be obtained by using Pr as a grain boundary diffusion material, and even if the amount of grain boundary diffusion material is increased, it can contribute to the generation of a strong magnetic field by having a residual magnetic density above a certain value.

[0021] The effects of the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art from the description in the claims.

[0022] FIG. 1 is a drawing for explaining a permanent magnet containing Pr as a grain boundary diffusion material according to an embodiment of the present invention.

[0023] FIG. 2 is a drawing illustrating a method for manufacturing a magnetic material using a grain boundary diffusion base material according to an embodiment of the present invention.

[0024] FIG. 3 is a drawing for explaining an example of the configuration of a base material used in a permanent magnet containing Pr of the present invention as a grain boundary diffusion material and a method for manufacturing the same.

[0025] Figure 4 is a graph of the coercivity and residual magnetic flux density when the grain boundary diffusion process is performed using base material A, and Figure 5 is a graph of the coercivity and residual magnetic flux density when the grain boundary diffusion process is performed using base material B.

[0026] FIG. 6 is a drawing for explaining an example of a motor manufactured using a permanent magnet according to an embodiment of the present invention.

[0027] FIG. 7 is a drawing for explaining an example of an actuator manufactured using a permanent magnet according to an embodiment of the present invention.

[0028] The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below but may be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims. Throughout the specification, the same reference numerals refer to the same components.

[0029] When one component is referred to as being "connected to" or "coupled to" another component, it includes cases where it is directly connected or coupled to the other component, or cases where another component is interposed. Conversely, when one component is referred to as being "directly connected to" or "directly coupled to" another component, it indicates that no other component is interposed. "And / or" includes each of the mentioned items and all combinations of one or more of them.

[0030] The terms used herein are for describing the embodiments and are not intended to limit the invention. In this specification, the singular form includes the plural form unless specifically stated otherwise in the text. As used herein, "comprises" and / or "comprising" do not exclude the presence or addition of one or more other components, steps, actions, and / or elements to the mentioned components, steps, actions, and / or elements.

[0031] Although terms such as "first," "second," etc., are used to describe various components, it goes without saying that these components are not limited by these terms. These terms are used merely to distinguish one component from another. Therefore, it goes without saying that the "first component" mentioned below may be the "second component" within the technical scope of the present invention.

[0032] Unless otherwise defined, all terms used in this specification (including technical and scientific terms) may be used in a meaning commonly understood by those skilled in the art to which the present invention pertains. Additionally, terms defined in commonly used dictionaries are not to be interpreted ideally or excessively unless explicitly and specifically defined otherwise.

[0033] FIG. 1 is a drawing for explaining a permanent magnet containing Pr as a grain boundary diffusion material according to an embodiment of the present invention.

[0034] Referring to FIG. 1, a permanent magnet (1) containing Pr as a grain boundary diffusion material according to an embodiment of the present invention may include a plurality of crystal grains (100) and a coercivity reinforcing layer (200) disposed between the plurality of crystal grains (100).

[0035] A permanent magnet (1) can be formed by diffusing a base material formed by a sintering process of magnet powder and a grain boundary diffusion material containing praseodymium (Pr) as the main component onto the base material at a high temperature.

[0036] Each of the plurality of crystal grains (100) is Nd2Fe 14 It can include a main phase of a tetragonal crystal structure, and the Nd-Fe-B structure can have high residual magnetic flux density and coercivity.

[0037] In some embodiments of the present invention, a plurality of crystal grains (100) may have a structure in which an element of a grain boundary diffusing material such as Pr is substituted at the Nd site. This may be the case for two reasons. First, during the sintering process of the magnet powder when forming the permanent magnet (1), the grain boundary diffusing material such as Pr is Nd2Fe 14 This is a case where Nd sites in the B crystal structure are substituted and evenly distributed within multiple crystal grains (100).

[0038] Secondly, the coercivity reinforcing layer (200) is formed along the grain boundaries between adjacent grains (100) by grain boundary diffusion, and subsequently, the grain boundary diffusion material can diffuse into the grains (100). However, the grains (100) may contain a relatively small amount of grain boundary diffusion material compared to the proportion of grain boundary diffusion material in the coercivity reinforcing layer (200).

[0039] Thus, Nd2Fe of multiple crystal grains (100) 14 When the columnar phase has a structure in which Pr, a grain boundary diffusing material, is substituted, it can affect the lattice constant, anisotropic magnetic field, Curie temperature, etc. of the columnar phase.

[0040] In addition, in some embodiments, Pr present within a plurality of crystal grains (100) may be segregated at the grain boundaries due to having an atomic radius larger than that of Nd. This tendency is particularly pronounced when Pr is present together with transition metals or non-metal elements such as Cu and Ga, and may affect the grain boundary diffusion process in the base material and the magnetic properties of the finished permanent magnet.

[0041] The coercivity reinforcing layer (200) may include a light rare earth element such as Pr and may be formed at the grain boundaries between a plurality of crystal grains (100). In this specification, the light rare earth element included in the coercivity reinforcing layer is described as Pr.

[0042] Meanwhile, the coercivity reinforcing layer (200) may further include one or more transition metal or non-metal elements selected from the group consisting of Cu, Al, Ga, and Ti. These elements can promote the diffusion of light rare earth elements at the grain boundaries and improve the characteristics of the grain boundaries, thereby contributing to the improvement of coercivity.

[0043] In some embodiments, the coercivity reinforcing layer (200) is (Pr, M) x O y It may include an oxide grain boundary phase of the form (where LRE is a light rare earth element, M is a transition metal or nonmetal, and x and y are positive integers). This oxide grain boundary phase has non-magnetic properties and can play a role in improving coercivity by suppressing exchange coupling between grains.

[0044] In some embodiments of the present invention, the permanent magnet (1) may correspond to SH Grade by having a coercivity of, for example, at least 17 kOe to a maximum of 20 kOe. The SH Grade permanent magnet (1) may be used in permanent magnets used in cameras or vehicles that operate in a temperature range of, for example, up to 150°C.

[0045] Or in another embodiment, the permanent magnet (1) may correspond to a UH Grade having a coercivity of up to 25 KOe. The UH Grade permanent magnet (1) may be used in an operating environment with a temperature range of, for example, up to 180°C, and more specifically, the UH Grade permanent magnet may be used for vehicles.

[0046] For a permanent magnet (1) having such high coercivity, a grain boundary diffusion process can be performed on a base material containing at least 1 wt% of Pr, and the completed permanent magnet (1) can be made to contain at least 1.5 to 10 wt% of a grain boundary diffusion material.

[0047] Or, in some other embodiments of the present invention, the permanent magnet (1) may have a residual magnetic flux density of at least 14.5 kG. For the permanent magnet (1) having such a residual magnetic flux density, the permanent magnet (1) completed by performing a grain boundary diffusion process on a base material that does not contain Pr may contain at least 0.5 to 4 wt% of a grain boundary diffusion material.

[0048] The manufacture of such a permanent magnet (1) and the performance of the manufactured permanent magnet are explained using Fig. 2, etc.

[0049] FIG. 2 is a diagram illustrating a method for manufacturing a permanent magnet containing Pr as a grain boundary diffusion material according to an embodiment of the present invention.

[0050] Referring to FIG. 2, a method for manufacturing a permanent magnet using a grain boundary diffusion base material according to an embodiment of the present invention includes the steps of providing a base material (S110), applying a grain boundary diffusion material to the base material (S120), and heating the applied grain boundary diffusion material and the base material to form a permanent magnet (S130).

[0051] The step (S110) of providing a grain boundary diffusion base material may include, for example, providing a base material having Nd, Fe, and B as main components, and optionally including one or more elements selected from the group consisting of light rare earth elements such as praseodymium (Pr) and transition metal or non-metal elements such as Cu, Al, Ga, Zr, Nb, Mo, Hf, Ta, W, and Si.

[0052] An example of the composition of such a base material is explained using Fig. 3.

[0053] FIG. 3 is a drawing for explaining an example of the configuration of a base material used in a permanent magnet containing Pr of the present invention as a grain boundary diffusion material and a method for manufacturing the same.

[0054] Referring to Figure 3, in base material A, Nd may be included in 23.76 wt% and Pr in 5.94 wt%, and in base material B, Co in 0.93 wt%, Co in 0.50 wt%, Zr in 0.35 wt%, Ga in 0.37 wt%, and Cu in 0.33 wt%, and most of the remaining elements excluding each of the elements in base material A may be Fe.

[0055] Meanwhile, in the B base material, ND may be included in the amount of 28.93 wt%, B in the amount of 0.93 wt%, Co in the amount of 0.91 wt%, Ga in the amount of 0.11 wt%, Cu in the amount of 0.15 wt%, Ti in the amount of 0.10 wt%, and Al in the amount of 0.09 wt%, and likewise, most of the remaining elements excluding each of these elements may be Fe.

[0056] The difference between base material A and base material B is whether or not Pr is included, and this can affect the coercivity and residual magnetic flux density of the permanent magnet (1) manufactured using base material A or base material B. This is explained using the experimental results of FIGS. 4 and 5.

[0057] Figure 4 is a graph of the coercivity and residual magnetic flux density when the grain boundary diffusion process is performed using base material A, and Figure 5 is a graph of the coercivity and residual magnetic flux density when the grain boundary diffusion process is performed using base material B.

[0058] First, referring to Figure 4, the horizontal axis values ​​1, 2, 3, 4, and 8 (wt%) correspond to the wt% range of grain boundary diffusion material that has undergone grain boundary diffusion on base material A, the left vertical axis corresponds to the residual magnetic flux density (unit kG), and the right vertical axis corresponds to the coercivity (unit kOe).

[0059] When a grain boundary diffusion process is performed on base material A using grain boundary diffusion materials in amounts of 1 wt%, 2 wt%, 3 wt%, 4 wt%, and 8 wt%, respectively, the coercivity of the permanent magnets formed through this process is 16.89 kOe, 20.15 kOe, 20.16 kOe, 26.25 kOe, and 28.00 kOe, and the residual magnetic flux density is 14.30 kG, 14.00 kG, 13.96 kG, 13.66 kG, and 12.90 kG, showing a tendency for coercivity to increase and residual magnetic flux density to decrease as the amount of grain boundary diffusion material increases. On the other hand, when grain boundary diffusion is not performed on base material A, the coercivity is approximately 16 kOe and the residual magnetic flux density is approximately 14.5 kG.

[0060] That is, by forming a permanent magnet (1) using a base material containing 1 wt% or more of Pr, such as base material A, the permanent magnet (1) can have SH grade, more preferably UH grade coercivity characteristics.

[0061] This is because, as a sufficient amount of Pr is present in the base material, Pr is used as a grain boundary diffusion material to influence the diffusivity of Pr during the grain boundary diffusion process, thereby reducing the Pr concentration gradient within the multiple crystal grains (100) and obtaining a more uniform Pr distribution, which is advantageous for improving coercivity. In addition, Pr contained in the base material can contribute to improving coercivity by suppressing the growth of crystal grains during the grain boundary diffusion process and maintaining magnetic anisotropy.

[0062] A permanent magnet (1) formed by a grain boundary diffusion process in which a base material A containing 1 wt% or more of Pr is formed may include 1.5 to 10 wt% of grain boundary diffusion material in a plurality of crystal grains (100) and a coercivity reinforcing layer (200). Alternatively, the permanent magnet (1) may have a coercivity of 20 kOe or more by including 2 to 10 wt% of grain boundary diffusion material in a plurality of crystal grains (100) and a coercivity reinforcing layer (200). Alternatively, the permanent magnet (1) may have a coercivity of 25 kOe or more by including 3 to 10 wt% of grain boundary diffusion material in a plurality of crystal grains (100) and a coercivity reinforcing layer (200).

[0063] Meanwhile, referring to Fig. 5, when a grain boundary diffusion process is performed on base material B using grain boundary diffusion materials in amounts of 1 wt%, 2 wt%, 4 wt%, and 8 wt%, respectively, the coercivity of the permanent magnets formed thereby is 9.68 kOe, 13.40 kOe, 15.43 kOe, and 15.63 kOe, and the residual magnetic flux density is 14.86 kG, 14.75 kG, 14.52 kG, and 14.52 kG, showing a tendency for coercivity to increase and residual magnetic flux density to decrease as the amount of grain boundary diffusion material increases. However, compared to the case where Pr is included in an amount of 1 wt% or more as with base material A mentioned earlier, the magnitude of the coercivity is small, and the increase in coercivity is not significant even with an increase in the amount of grain boundary diffusion material.

[0064] Meanwhile, when grain boundary diffusion is not performed on the B base material, the coercivity is about 9.6 kOe and the residual magnetic flux density is about 14.9 kG. Even with an increase in the amount of grain boundary diffusion material, the residual acceleration density is maintained at 14.5 kG, so the decrease in residual acceleration density does not exceed 3%. This means that compared to the permanent magnet (1) using the A base material mentioned earlier, it has a residual acceleration density value of more than 10% and can generate a larger magnetic field.

[0065] A permanent magnet (1) formed by a grain boundary diffusion process of a B base material that does not contain Pr may contain 0.5 to 4 wt% of grain boundary diffusion material in a plurality of crystal grains (100) and a coercivity reinforcing layer (200).

[0066] Referring again to FIG. 2, in the step (S120) of applying a grain boundary diffusion material to a grain boundary diffusion substrate, a grain boundary diffusion material can be applied to a grain boundary diffusion substrate by at least one method among spray coating, immersion coating, screen printing, electrophoresis, sputtering, and vacuum deposition.

[0067] Finally, in the step (S130) of forming a permanent magnet by heating the applied grain boundary diffusion material and the base material, a permanent magnet can be formed by heat-treating the base material coated with the grain boundary diffusion material at a high temperature in a vacuum or inert atmosphere.

[0068] FIG. 6 is a drawing for explaining an example of a motor manufactured using a permanent magnet according to an embodiment of the present invention.

[0069] Referring to FIG. 6, the motor (1000) may include a housing (1100), a stator (1200), a rotor (1300), and a rotating shaft (1400), etc.

[0070] The motor (1000) may be a drive motor that operates in a high-temperature environment, such as an electric vehicle (EV) or a hybrid vehicle (HEV).

[0071] The housing (1100) may form a space for accommodating the stator (1200), rotor (1300), and rotation axis (1400). The housing (1100) may include a metal material, for example, to ensure good heat generation performance, but the present invention is not limited thereto.

[0072] The stator (1200) may be fixedly positioned inside the housing (1100) and arranged to surround the rotor (1200) at a certain distance from the rotor (1200). The stator (1200) may include a plurality of cores, and a coil may be wound on each core.

[0073] The rotor (1300) can interact with the stator (1200) while rotating around the rotation axis (1400). The rotor (1300) may include a permanent magnet (1310) disposed on the outer surface of the rotor core. The permanent magnet (1310) may be a permanent magnet formed using the base material A of FIG. 4. That is, the permanent magnet (1310) may be a permanent magnet having enhanced coercivity to maintain magnetic force even in a high-temperature environment, and may be, for example, an SH grade or UH grade permanent magnet.

[0074] FIG. 7 is a drawing for explaining an example of an actuator manufactured using a permanent magnet according to an embodiment of the present invention. FIG. 7 is described as a side cross-sectional view of a structure in which an actuator including a permanent magnet is coupled to a lens module (2000).

[0075] Referring to FIG. 7, the lens module (2000) may include a housing (2010), a lens part (2020), an actuator (2100), etc.

[0076] The housing (2010) forms the exterior of the lens module (2000) and can accommodate the lens portion (2020) and the actuator (2100), etc. The housing (2010) can be opened in an area facing the lens portion (2020) to expose the lens portion (2020), and a cover glass can be installed in that area to protect the lens portion (2020).

[0077] The lens portion (2020) may include a lens barrel containing one or more lenses.

[0078] The actuator (2100) can drive the lens unit (2020) by receiving power. The actuator (2100) can move one or more lenses included in the lens unit (2020) in the up and down direction by including a voice coil motor (VCM).

[0079] The actuator (2100) may include a bobbin (2110), a coil (2120), and a permanent magnet (2130), etc.

[0080] The bobbin (2110) accommodates a lens portion (2020) on its inner side and can move one or more lenses included in the lens portion (2020) in the direction of the optical axis by driving according to control.

[0081] The coil (2120) can drive the bobbin (2110) by receiving power to form an electromagnetic force and interacting with the magnetic force formed by the permanent magnet (2130).

[0082] A permanent magnet (2130) may be installed on the housing (2010) side facing the coil (2120). Although the permanent magnet (2130) in FIG. 5 is shown to have a rectangular cross-sectional shape, the present invention is not limited thereto, and a permanent magnet (2130) of various shapes, such as a square or a trapezoid, may be included in the actuator (2100).

[0083] The permanent magnet (2130) may be a permanent magnet formed using the B base material described above using FIG. 5. That is, the permanent magnet (2130) may be a permanent magnet with a residual magnetic flux density of 14.5 kG or more, which is not a coercive force to ensure a high-temperature operating environment, but can generate a strong magnetic field.

[0084] In summary, a permanent magnet containing Pr as a grain boundary diffusion material according to an embodiment of the present invention can have enhanced coercivity by including Pr as a grain boundary diffusion material, and can be advantageous for the production environment of permanent magnet products by not using heavy rare earth elements such as Dy or Tb.

[0085] In addition, the permanent magnet according to the embodiment of the present invention can have an improved crystal grain structure and a structure of a coercivity reinforcing layer by performing a grain boundary diffusion process using a base material containing 1 wt% or more of Pr, which can provide improved coercivity for a permanent magnet capable of operating in a high-temperature environment. Meanwhile, even when using a base material that does not contain 1 wt% or more of Pr, an effect of improving coercivity can be obtained by using Pr as a grain boundary diffusion material, and even if the amount of grain boundary diffusion material is increased, it can contribute to the generation of a strong magnetic field by having a residual magnetic density above a certain value.

[0086] Although embodiments of the present invention have been described above with reference to the attached drawings, those skilled in the art will understand that the present invention may be implemented in other specific forms without changing its technical concept or essential features. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive.

Claims

1. A plurality of crystal grains comprising a columnar phase of Nd-Fe-B; and It includes a coercivity reinforcing layer disposed between the plurality of crystal grains, wherein The above coercivity reinforcing layer includes Pr, Ga, and Cu, and The mass ratio of the above Ga is 0.1 wt% to 0.4 wt%, and The mass ratio of the above Cu is 0.1 wt% to 0.4 wt%, Permanent magnet containing Pr as a grain boundary diffusion material.

2. In Paragraph 1, The mass ratio of the grain boundary diffusion material in the plurality of crystal grains and the coercivity reinforcing layer is 1.5 to 10 wt%, Permanent magnet containing Pr as a grain boundary diffusion material.

3. In Paragraph 2, The mass ratio of the grain boundary diffusion material in the plurality of crystal grains and coercivity reinforcing layers is 2 to 10 wt%, and The coercivity of the above permanent magnet is 20 kOe or more, Permanent magnet containing Pr as a grain boundary diffusion material.

4. In Paragraph 1, The grain boundary diffusion material included in the plurality of crystal grains and the coercivity reinforcing layer above contains 0.5 to 4 wt% silver, Permanent magnet containing Pr as a grain boundary diffusion material.

5. In Paragraph 4, The residual magnetic flux density of the above permanent magnet is 14.5 kG or more, Permanent magnet containing Pr as a grain boundary diffusion material.

6. Step of providing the base material; A step of applying a grain boundary diffusion material to the above base material; and The method includes the step of forming a permanent magnet by heating the coated grain boundary diffusion material and the base material, wherein The above permanent magnet is, Multiple crystal grains containing a columnar phase of Nd-Fe-B; It includes a coercivity reinforcing layer disposed between the plurality of crystal grains, wherein The above coercivity reinforcing layer includes Pr, Ga, and Cu, and The mass ratio of the above Ga is 0.1 wt% to 0.4 wt%, and The mass ratio of the above Cu is 0.1 wt% to 0.4 wt%, A method for manufacturing a permanent magnet containing Pr as a grain boundary diffusion material.

7. In Paragraph 6, The above base material comprises at least 1 wt% of Pr, A method for manufacturing a permanent magnet containing Pr as a grain boundary diffusion material.

8. In Paragraph 7, The step of applying a grain boundary diffusion material to the above base material is, A step comprising applying 1 wt% to 8 wt% of a grain boundary diffusion material to the above base material, A method for manufacturing a permanent magnet containing Pr as a grain boundary diffusion material.

9. In Paragraph 8, The step of applying a grain boundary diffusion material to the above base material is, The method includes the step of applying 2 wt% to 8 wt% of a grain boundary diffusion material to the above base material, The coercivity of the above permanent magnet is 20 kOe or more, A method for manufacturing a permanent magnet containing Pr as a grain boundary diffusion material.

10. In Paragraph 6, The above base material does not contain Pr, and The step of applying a grain boundary diffusion material to the above base material is, The method includes the step of applying 1 wt% to 8 wt% of a grain boundary diffusion material to the above base material, The residual magnetic flux density of the above permanent magnet is 14.5 kG or more, A method for manufacturing a permanent magnet containing Pr as a grain boundary diffusion material.

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