Rare earth magnet and method for producing the same

Abstract

Provided are a rare earth magnet and a method for producing the same while maintaining an improved coercivity and further reducing the amount of heavy rare earth elements used. The rare earth magnet disclosed in the present invention comprises a main phase 10 and a grain boundary phase 20. The main phase 10 is composed of R 1 2T 14 B(R 1 is a rare earth element, etc., T is a predetermined transition element, etc.) The main phase 10 has a core portion 12 and a shell portion 14. 2 and Ce(R 2 is a predetermined heavy rare earth element) and the existence ratio thereof is set as R 2 4f Ce 4f and the shell 14 occupies the 4g crystal position R 2 The existence ratio of Ce is R 2 4g Ce 4g When 0.44≤R 2 4g / (R 2 4f +R 2 4g )≤0.70 and 0.04≤(Ce 4f +Ce 4g ) / (R 2 4f +R 2 4g The method for producing a rare earth magnet disclosed in the present invention uses a rare earth magnet containing at least R 2 and Ce modified materials.

Description

Technical Field

[0001] The present disclosure relates to a rare earth magnet and a method for manufacturing the same. The present disclosure particularly relates to a rare earth magnet having excellent coercivity. 1 -TB series rare earth magnet and its manufacturing method. 1 is one or more elements selected from Y and rare earth elements, and T is one or more transition elements including one or more elements selected from Fe, Co and Ni as essential elements. Background Art

[0002] R 1 -TB series rare earth magnets are composed of R 1 2T 14 B represents the main phase. 1 -TB-based rare earth magnets exhibit magnetic properties through this main phase.

[0003] R 1 -TB series rare earth magnets are represented by the use of Nd as R 1 However, in recent years, attempts have been made to select a variety of rare earth elements as R according to the required functions (properties). 1 In addition, as R 1 When selecting a plurality of rare earth elements, an attempt is made to change the arrangement of the rare earth elements in the main phase according to the type of rare earth magnet.

[0004] For example, Patent Document 1 discloses an R 1 -TB rare earth magnets, in which the abundance ratios of Ce occupying the 4f crystal position and the 4g crystal position in the main phase are respectively defined as Ce 4f and Ce 4g When 0.8≤Ce 4f / (Ce 4f +Ce 4g )≤1.0. Moreover, Patent Document 1 discloses that a rare earth magnet satisfying this relationship is attached to the rotor of a motor, and even if the motor rotates and centrifugal force acts on the rare earth magnet, the rare earth magnet is difficult to peel off from the rotor, and its adhesion is high. Furthermore, regarding the 4f crystal position and 4g crystal position in the main phase, reference can be made to Non-Patent Document 1.

[0005] In addition, in R 1 -TB series rare earth magnets, as a selection of multiple rare earth elements as R 1 The conventional method is to use Nd-TB rare earth magnet as a precursor and diffuse and infiltrate heavy rare earth elements into the precursor. It is known that even if the amount of expensive heavy rare earth elements used is relatively small, the coercive force will be improved.

[0006] Prior Art Literature

[0007] Patent Document 1: International Publication No. 2014 / 148145

[0008] Non-patent literature 1: K. Saito et al., “Quantitative evaluation of site preference in Dy-substituted Nd2Fe 14 B”, Journal of Alloys and Compounds, Volume 721, October 15, 2017, Pages 476-481 Summary of the invention

[0009] If heavy rare earth elements are diffused and plated into the rare earth magnet precursor, the coercive force is improved as described above. However, the price of heavy rare earth elements is high, and it is expected that the price of heavy rare earth elements will rise further in the future. Therefore, the inventors have found that it is desirable to further reduce the amount of heavy rare earth elements used while maintaining the improvement of coercive force.

[0010] The present disclosure is made to solve the above-mentioned problems. The purpose of the present disclosure is to provide a rare earth magnet and a method for producing the same, in which the amount of heavy rare earth elements used is further reduced while maintaining an improved coercive force.

[0011] The present inventors have conducted repeated and in-depth studies to achieve the above-mentioned objectives and have completed the rare earth magnet and the method for manufacturing the same disclosed in the present invention. The rare earth magnet and the method for manufacturing the same disclosed in the present invention include the following schemes.

[0012] <1> A rare earth magnet comprising a main phase and a grain boundary phase existing around the main phase, wherein the main phase is composed of R 1 2T 14 B(R 1 is one or more elements selected from Y and rare earth elements, T is one or more transition elements with one or more elements selected from Fe, Co and Ni as essential elements,

[0013] The main phase has a core portion and a shell portion existing around the core portion,

[0014] The shell R 2 (R 2 is one or more elements selected from Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) has a molar ratio higher than that of the R 2 The molar ratio of

[0015] The R occupying the 4f crystal position of the shell 2 The existence ratio of Ce is R 2 4f Ce 4fand the R occupying the 4g crystal position of the shell 2 The existence ratio of Ce is R 2 4g Ce 4g When , the following relationship is satisfied:

[0016] 0.44≤R 2 4g / (R 2 4f +R 2 4g )≤0.70 and

[0017] 0.04≤(Ce 4f +Ce 4g ) / (R 2 4f +R 2 4g ).

[0018] <2> according to <1> Record rare earth magnets,

[0019] The R 1 Ce, Nd and R 2 One or more elements selected from Y and rare earth elements as essential elements,

[0020] The T is one or more transition elements which are one or more elements selected from Fe and Co as essential elements,

[0021] In the core, the R of the core as a whole 1 The total molar ratio of Y, Sc, La and Ce is less than 0.10.

[0022] In the core portion, the molar ratio of Co is less than 0.10 based on T of the entire core portion, and

[0023] The rare earth magnet satisfies the following relationship:

[0024] 0.47≤R 2 4g / (R 2 4f +R 2 4g )≤0.54.

[0025] <3> according to <1> Record rare earth magnets,

[0026] The R 1 Ce, La, Nd and R 2 One or more elements selected from Y and rare earth elements as essential elements,

[0027] The T is one or more transition elements which are one or more elements selected from Fe and Co as essential elements,

[0028] In the core, the R of the core as a whole 1 The total molar ratio of Y, Sc and Ce is less than 0.10, and the molar ratio of La is 0.01 to 0.20.

[0029] In the core portion, the molar ratio of Co is 0.10 to 0.40 based on T of the entire core portion, and

[0030] The rare earth magnet satisfies the following relationship:

[0031] 0.50≤R 2 4g / (R 2 4f +R 2 4g )≤0.60.

[0032] <4> according to <1> Record rare earth magnets,

[0033] The R 1 Ce, Nd and R 2 One or more elements selected from Y and rare earth elements as essential elements,

[0034] The T is one or more transition elements which are one or more elements selected from Fe and Co as essential elements,

[0035] In the core, the R of the core as a whole 1 The total molar ratio of Y, Sc, La and Ce is 0.10 to 0.90.

[0036] In the core portion, the molar ratio of Co is 0.40 or less based on T of the entire core portion, and

[0037] The rare earth magnet satisfies the following relationship:

[0038] 0.44≤R 2 4g / (R 2 4f +R 2 4g )≤0.51.

[0039] <5> according to <1> ~ <4> A rare earth magnet as described in any one of the items,

[0040] A sub-shell portion is provided between the core portion and the shell portion, and

[0041] The R of the secondary shell 4(R 4 is one or more elements selected from Pr, Nd, Pm, Sm and Eu) has a molar ratio higher than that of R 4 molar ratio.

[0042] <6> A method for manufacturing a rare earth magnet is to manufacture <1> The method of producing a rare earth magnet according to item 1 comprises the following steps:

[0043] A rare earth magnet precursor is prepared, the rare earth magnet precursor comprising a main phase and a grain boundary phase existing around the main phase, wherein the main phase is composed of R 1 2T 14 B(R 1 is one or more elements selected from Y and rare earth elements, and T is one or more transition elements with one or more elements selected from Fe, Co and Ni as essential elements); and

[0044] Make it contain at least R 2 The modified material of Ce is diffused and infiltrated into the interior of the rare earth magnet precursor.

[0045] <7> according to <6> A method for producing a rare earth magnet as described in item

[0046] In the rare earth magnet precursor,

[0047] The R 1 is one or more elements selected from Y and rare earth elements with Nd as an essential element,

[0048] The T is one or more transition elements which are one or more elements selected from Fe and Co as essential elements,

[0049] With the R 1 The total molar ratio of Y, Sc, La and Ce is less than 0.10, and

[0050] Based on the T, the molar ratio of Co is less than 0.10.

[0051] <8> according to <6> A method for producing a rare earth magnet as described in item

[0052] In the rare earth magnet precursor,

[0053] The R 1 is one or more elements selected from Y and rare earth elements with La and Nd as essential elements,

[0054] The T is one or more transition elements which are one or more elements selected from Fe and Co as essential elements,

[0055] With the R 1The total molar ratio of Y, Sc and Ce is less than 0.10, and the molar ratio of La is 0.01 to 0.20, and

[0056] Based on the above T, the molar ratio of Co is 0.10 to 0.40.

[0057] <9> according to <6> A method for producing a rare earth magnet as described in item

[0058] In the rare earth magnet precursor,

[0059] The R 1 is one or more elements selected from Y and rare earth elements with Ce and Nd as essential elements,

[0060] The T is one or more transition elements which are one or more elements selected from Fe and Co as essential elements,

[0061] With the R 1 The total molar ratio of Y, Sc, La and Ce is 0.10 to 0.90, and

[0062] Based on the above T, the molar ratio of Co is 0.40 or less.

[0063] <10> according to <6> ~ <9> The method for producing a rare earth magnet according to any one of the items, further comprising the following steps:

[0064] Before the modified material is diffused and plated into the rare earth magnet precursor, a pre-modified material is diffused and plated into the rare earth magnet precursor.

[0065] The pre-modified material contains at least R 4 (R 4 is one or more elements selected from Pr, Nd, Pm, Sm and Eu).

[0066] According to the present disclosure, most of Ce occupies the 4f crystal position in the main phase, and most of the heavy rare earth elements that contribute to the improvement of coercivity tend to occupy the 4g crystal position in the main phase that contributes to the improvement of coercivity. As a result, a higher coercivity than that predicted by the content ratio of the heavy rare earth elements in the rare earth elements can be obtained. In addition, such a rare earth magnet can be obtained by diffusing and infiltrating a modified material containing both heavy rare earth elements and Ce into a rare earth magnet precursor. Therefore, according to the present disclosure, a rare earth magnet and a method for manufacturing the same can be provided in which the amount of heavy rare earth elements used is further reduced while maintaining the improvement of coercivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Figure 1 This is an explanatory diagram schematically showing an example of the structure of the rare earth magnet disclosed in the present invention.

[0068] Figure 2A This is an explanatory diagram schematically showing an example of a state in which a modifying material is brought into contact with a rare earth magnet precursor.

[0069] Figure 2B This is an explanatory diagram schematically showing an example of a state in which a modifying material is diffused and plated into a grain boundary phase of a rare earth magnet precursor.

[0070] Figure 2C This is an explanatory diagram schematically showing an example of a state in which a core / shell structure is formed in the main phase.

[0071] Figure 3 It is an explanatory diagram schematically showing the crystal structure of the main phase.

[0072] Figure 4 It is a coordinate diagram showing the ionic radius of each rare earth element.

[0073] Figure 5 This is an explanatory diagram schematically showing an example of a structure in which the rare earth magnet disclosed in the present invention has a sub-shell portion.

[0074] Fig. 6A This is an explanatory diagram schematically showing an example of a state in which a preliminary modified material is brought into contact with a rare earth magnet precursor.

[0075] Figure 6B This is an explanatory diagram schematically showing an example of a state in which a preliminary reforming material is diffused and infiltrated into a grain boundary phase of a rare earth magnet precursor.

[0076] Figure 6C This is an explanatory diagram schematically showing an example of a state in which a sub-shell is formed in a main phase.

[0077] Fig.6D This is an explanatory diagram schematically showing an example of a state in which a modifying material is brought into contact with a rare earth magnet precursor having a main phase in which a sub-shell is formed.

[0078] Fig. 6E This is an explanatory diagram schematically showing an example of a state in which a modifying material is diffused and infiltrated into a grain boundary phase of a rare earth magnet precursor in which a subshell is formed in a main phase.

[0079] Fig. 6F This is an explanatory diagram schematically showing an example of a state in which the main phase forms a core / sub-shell / shell structure.

[0080] Figure 7 This is a graph showing the relationship between the molar ratio of Ce in the modified material and the coercive force for the samples in Table 1.

[0081] Figure 8 This is a graph showing the relationship between the molar ratio of Ce in the modified material and the coercive force for the samples in Table 2.

[0082] Fig. 9This is a graph showing the relationship between the molar ratio of Ce in the modified material and the coercive force for the samples in Table 3.

[0083] Fig.10 For the samples in Table 1, R 2 4g / (R 2 4f +R 2 4g ) and coercive force.

[0084] Fig.11 For the samples in Table 2, R 2 4g / (R 2 4f +R 2 4g ) and coercive force.

[0085] Fig.12 For the samples in Table 3, R 2 4g / (R 2 4f +R 2 4g ) and coercive force.

[0086] Description of Reference Numerals

[0087] 10 Main phase

[0088] 12 Nuclear

[0089] 14 Shell

[0090] 16 Sub-shell

[0091] 20 Grain boundary phase

[0092] 50 Rare Earth Magnet Precursor

[0093] 60 Modified materials

[0094] 62 Pre-modified materials

[0095] 100 Rare earth magnet disclosed in the present invention DETAILED DESCRIPTION

[0096] Hereinafter, embodiments of the rare earth magnet and the method for producing the same according to the present disclosure will be described in detail. Note that the embodiments described below do not limit the rare earth magnet and the method for producing the same according to the present disclosure.

[0097] Although not bound by theory, the reason why the rare earth magnet disclosed in the present invention has a higher coercive force than predicted based on the content ratio of the heavy rare earth element is explained using the accompanying drawings. In addition, although not bound by theory, the reason why the rare earth magnet disclosed in the present invention is obtained by diffusion-plating a modified material containing both the heavy rare earth element and Ce is also explained using the accompanying drawings.

[0098] Figure 1 1 is an explanatory diagram schematically showing an example of the structure of the rare earth magnet 100 of the present disclosure. The rare earth magnet 100 of the present disclosure includes a main phase 10 and a grain boundary phase 20. The grain boundary phase 20 exists around the main phase 10. In addition, the main phase 10 includes a core portion 12 and a shell portion 14. The shell portion 14 exists around the core portion 12.

[0099] like Figure 1 As shown, the main phase 10 of the rare earth magnet 100 of the present disclosure has a core / shell structure. The core / shell structure is obtained by diffusion-plating the modifying material 60 into the rare earth magnet precursor 50. This will be described using the drawings.

[0100] Figure 2A This is an explanatory diagram schematically showing an example of a state in which the modifying material 60 is brought into contact with the rare earth magnet precursor 50 . Figure 2B This is an explanatory diagram schematically showing an example of a state in which the modifying material 60 is diffused and permeated into the grain boundary phase 20 of the rare earth magnet precursor 50 . Figure 2C This is an explanatory diagram schematically showing an example of a state in which a core / shell structure is formed in the main phase.

[0101] like Figure 2A As shown, before the modified material 60 is diffused and plated into the rare earth magnet precursor 50, the main phase 10 is a single phase. A single phase refers to a phase with a substantially single crystal structure and composition. Figure 2A As shown, when the modified material 60 is heated in a state of contact with the rare earth magnet precursor 50, as shown in FIG. Figure 2B As shown, the modified material 60 diffuses and infiltrates into the grain boundary phase 20. Then, as shown in FIG. Figure 2C As shown in FIG. 1 , the modified material 60 diffused and infiltrated into the grain boundary phase 20 further diffused and infiltrated into the outer periphery of the main phase 10 to form a core portion 12 and a shell portion 14. When the core / shell structure is formed in the single-phase main phase 10, a portion of the rare earth elements existing in the outer periphery of the single-phase main phase 10 is exchanged with a portion of the rare earth elements of the modified material 60 diffused and infiltrated into the grain boundary phase 20 to form the shell portion 14. On the other hand, the core portion 12 maintains the same composition as the single-phase main phase 10. The main phase 10 of the rare earth magnet 100 of the present disclosure obtained in this way is as shown in FIG. Figure 1 As shown, it has a core / shell structure.

[0102] Next, the crystal structure of the main phase 10 will be described.

[0103] Figure 3 2 is an explanatory diagram schematically showing the crystal structure of the main phase 10 . Figure 3 The source is non-patent document 1. Figure 4 It is a coordinate diagram showing the ionic radius of each rare earth element.

[0104] like Figure 3 As shown, in the main phase 10, in either the core portion 12 or the shell portion 14, R 1 , T and B are present in a ratio of 2:14:1 in terms of atomic ratio, and all have a roughly tetragonal structure. 1 Occupies the 4f crystal position inside the tetragonal crystal and the 4g crystal position facing the outside of the tetragonal crystal. 1 Atoms with small ionic radius tend to occupy 4f crystal position, while atoms with large ionic radius tend to occupy 4g crystal position.

[0105] The magnetic anisotropy of the 4f crystal position is roughly orthogonal to the overall magnetic anisotropy of the main phase crystal structure. 1 It hardly contributes to the improvement of the anisotropic magnetic field. On the other hand, the 4g crystal position is roughly parallel to the overall magnetic anisotropy of the crystal structure of the main phase. Therefore, R occupying the 4g crystal position 1 The contribution to the improvement of the anisotropic magnetic field is great. In addition, heavy rare earth elements contribute to the improvement of the anisotropic magnetic field compared with rare earth elements other than heavy rare earth elements. Therefore, if as many heavy rare earth elements as possible occupy the 4g position, it further contributes to the improvement of the anisotropic magnetic field, and as a result, it further contributes to the improvement of the coercive force.

[0106] In addition, if the heavy rare earth element is more in the shell 14 than in the core 12, the anisotropic magnetic field of the main phase 10 as a whole becomes higher, and the coercive force can be improved. This is because the nucleation of magnetization reversal and the nuclear growth of adjacent main phase particles can be suppressed on the surface of the main phase 10 (the surface of the shell 14). Therefore, it has been conventionally performed to diffuse and permeate the modified material 60 containing the heavy rare earth element in the rare earth magnet precursor 50 that does not substantially contain the heavy rare earth element, so that the heavy rare earth element exists only in the shell 14 that contributes greatly to the improvement of the anisotropic magnetization. In addition, the existence of expensive heavy rare earth elements in the core 12 that contributes little to the improvement of the anisotropic magnetization is avoided.

[0107] In the rare earth magnet 100 disclosed in the present invention, the presence of expensive heavy rare earth elements in the core 12 is avoided as much as possible, and most of the heavy rare earth elements are present in the shell 14. In addition, the positions occupied by the heavy rare earth elements in the shell 14 are specially designed. That is, in the rare earth magnet 100 disclosed in the present invention, most of the heavy rare earth elements occupy the 4g crystal position in the shell 14. In addition, the modifying material 60 containing both the heavy rare earth elements and Ce is diffused and plated in such a manner that most of the heavy rare earth elements occupy the 4g crystal position in the shell 14.

[0108] In the past, it was believed that if the modified material 60 contained a rare earth element other than a heavy rare earth element, the diffusion and plating amount of the heavy rare earth element into the shell portion 14 would be relatively reduced, the anisotropic magnetic field would be reduced, and the coercive force would be reduced. In particular, it was believed that if the modified material 60 contained a light rare earth element such as Ce, the anisotropic magnetic field would be reduced, and the reduction in coercive force would be significant. However, although not being bound by theory, it is believed that when the modified material 60 containing both a heavy rare earth element and Ce is used, the coercive force is improved compared to the past for the following reasons.

[0109] Most of the rare earth elements in the main phase 10 are trivalent. However, it is known that Ce in the main phase 10 is tetravalent. Figure 4 As shown in Figure 1, the ion radius of Ce ions (quadrivalent) is smaller than that of other rare earth element ions. 1 ), atoms with small ionic radius tend to occupy 4f crystal position, and atoms with large ionic radius tend to occupy 4g crystal position. In addition, as described above, if the modified material 60 is diffused and infiltrated into the rare earth magnet precursor 50, a portion of the rare earth elements existing in the peripheral portion of the single-phase main phase 10 and a portion of the rare earth elements of the modified material 60 diffused and infiltrated into the grain boundary phase 20 are exchanged to form a shell 14. During this exchange, if the modified material 60 contains both heavy rare earth elements and Ce, Ce preferentially occupies the 4f crystal position of the shell 14. As a result, the heavy rare earth element tends to occupy the 4g crystal position of the shell 14. This is because Figure 4 As shown, the ionic radius of Ce (4 valence) is smaller than that of heavy rare earth elements. In addition, as mentioned above, the 4g crystal position contributes more to the improvement of the anisotropic magnetic field than the 4f crystal position. Therefore, when most of the heavy rare earth elements occupy the 4g crystal position, the coercive force increases.

[0110] Ce greatly reduces the anisotropic magnetic field. However, Ce helps heavy rare earth elements that help to increase the anisotropic magnetic field occupy the 4g crystal position, and Ce itself occupies the 4f crystal position that has almost no effect on increasing the anisotropic magnetic field. Thus, it is avoided that the heavy rare earth elements occupy the 4f crystal position that has almost no effect on the increase of the anisotropic magnetic field. As a result, it is possible to solve the problem that the coercive force cannot be increased accordingly despite the use of expensive heavy rare earth elements.

[0111] Hereinafter, based on the findings described so far, constituent elements of the rare earth magnet and the method for producing the same according to the present disclosure will be described.

[0112] Rare Earth Magnets

[0113] First, the constituent elements of the rare earth magnet of the present disclosure will be described.

[0114] like Figure 1As shown, the rare earth magnet 100 of the present disclosure includes a main phase 10 and a grain boundary phase 20. Hereinafter, the main phase 10 and the grain boundary phase 20 will be described separately.

[0115] <Main Phase>

[0116] The main phase 10 has a core 12 and a shell 14. The shell 14 exists around the core 12. The rare earth magnet 100 disclosed in the present invention embodies magnetism through the main phase 10. The particle size of the main phase 10 is not particularly limited. The average particle size of the main phase 10 can be 1.0 μm or more, 1.1 μm or more, 1.2 μm or more, 1.3 μm or more, 1.5 μm or more, 2.0 μm or more, 3.0 μm or more, 4.0 μm or more, 5.0 μm or more, 5.9 μm or more, or 6.0 μm or more, and can be 20 μm or less, 15 μm or less, 10 μm or less, 9.0 μm or less, 8.0 μm or less, or 7.0 μm or less. The rare earth magnet 100 disclosed in the present invention is obtained by diffusion-plating a modifying material 60 containing both a heavy rare earth element and Ce. Since the modifying material contains a heavy rare earth element, the diffusion-plating temperature becomes relatively high. Therefore, by having the main phase 10 have an average particle size as described above, it is easy to suppress the coarsening of the main phase 10 during the diffusion and infiltration of the modified material. Furthermore, the "average particle size" of the main phase is measured as follows. In a scanning electron microscope image or a transmission electron microscope image, a certain area observed from the perpendicular direction of the easy magnetization axis is specified, and a plurality of lines are drawn on the main phase existing in the certain area in the perpendicular direction of the easy magnetization axis, and the main phase diameter (length) is calculated based on the distance between the points intersecting within the main phase particles (cutting method). When the cross section of the main phase is close to a circle, it is converted to the equivalent diameter of the projected area circle. When the cross section of the main phase is close to a rectangle, it is approximately converted to a rectangular parallelepiped. The distribution (particle size distribution) of the diameter (length) obtained in this way is D 50 The value is the average particle size.

[0117] The main phase 10 has a molar ratio of R 1 2T 14 B represents the composition. 1It is one or more elements selected from Y and rare earth elements. T is one or more transition elements with one or more elements selected from Fe, Co and Ni as essential elements. Y is yttrium, Fe is iron, Co is cobalt, and Ni is nickel. "Essential elements" means that elements other than the target element may be included within the limit that the effect of the rare earth magnet and the manufacturing method thereof disclosed in the present invention is not impaired. That is, the so-called "T is one or more elements selected from Fe, Co and Ni as essential elements" means that T may contain transition elements other than Fe, Co and Ni within the limit that the effect of the rare earth magnet and the manufacturing method thereof disclosed in the present invention is not impaired. Typically, the total of one or more elements selected from Fe, Co and Ni in T can be 80 atomic % or more, 90 atomic % or more, 95 atomic % or more, 98 atomic % or more or 99 atomic % or more, and can be 100 atomic %. As transition elements other than Fe, Co and Ni, for example, Ga, Al and Cu can be cited. These elements are mainly present in the grain boundary phase 20, but part of them may also be present in the main phase 10 in an interstitial or substitutional manner.

[0118] In this specification, unless otherwise specified, rare earth elements are 16 elements, namely Sc, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu. Among them, unless otherwise specified, Sc, La and Ce are light rare earth elements. In addition, unless otherwise specified, Pr, Nd, Pm, Sm and Eu are medium rare earth elements. Moreover, unless otherwise specified, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu are heavy rare earth elements. Furthermore, generally speaking, the scarcity of heavy rare earth elements is high, and the scarcity of light rare earth elements is low. The scarcity of medium rare earth elements is between that of heavy rare earth elements and light rare earth elements. Furthermore, Sc is scandium, La is lanthanum, Ce is cerium, Pr is praseodymium, Nd is neodymium, Pm is promethium, Sm is samarium, Eu is europium, Gd is gadolinium, Tb is terbium, Dy is dysprosium, Ho is holmium, Er is erbium, Tm is thulium, Yb is ytterbium, and Lu is lutetium.

[0119] like Figure 3 As shown, in the main phase 10, in either the core portion 12 or the shell portion 14, R 1 , T and B are present in a ratio of 2:14:1 in terms of atomic number, and all have a roughly tetragonal structure. 1 It occupies the 4f crystal position inside the tetragonal crystal and the 4g crystal position facing the outside of the tetragonal crystal. The 4f crystal position and the 4g crystal position will be described in detail later.

[0120] As described above, the rare earth magnet 100 of the present disclosure is obtained by diffusion-plating the modifying material 60 containing both the heavy rare earth element and Ce in the rare earth magnet precursor 50. The core 12 and the shell 14 are obtained by the diffusion-plating. Therefore, the core 12 has the original composition of the main phase 10 of the rare earth magnet precursor 50. In addition, in the shell 14, a part of the rare earth elements existing in the peripheral part of the main phase 10 of the rare earth magnet precursor 50 and a part of the rare earth elements of the modifying material 60 are exchanged. As a result, the molar ratio of the heavy rare earth element in the shell 14 is higher than the molar ratio of the heavy rare earth element in the core 12. The heavy rare earth element is composed of R 2 Indicates that R 2 is one or more elements selected from Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu. Therefore, in the rare earth magnet 100 of the present disclosure, R in the shell 14 2 The molar ratio is higher than that of R 2 From the perspective of increasing the coercive force without reducing the residual magnetization as much as possible, R 2 Preferably, it is one or more elements selected from Tb and Dy, and more preferably Tb.

[0121] R in the shell 14 2 The molar ratio of R in the core 12 2 The difference in the molar ratio can be, for example, 0.01 or more, 0.05 or more, 0.10 or more, 0.11 or more, 0.12 or more, 0.13 or more, 0.14 or more, or 0.15 or more, and can be 0.50 or less, 0.45 or less, 0.40 or less, 0.38 or less, 0.37 or less, 0.36 or less, 0.34 or less, 0.32 or less, 0.30 or less, 0.29 or less, 0.28 or less, 0.27 or less, 0.26 or less, 0.24 or less, 0.22 or less, or 0.20 or less.

[0122] Next, the core portion 12 and the shell portion 14 will be described in detail. For the sake of convenience, the shell portion 14 will be described first.

[0123] <Shell>

[0124] like Figure 3 As shown, R 1 Occupies the 4f crystal position inside the tetragonal crystal and the 4g crystal position facing the outside of the tetragonal crystal. 1 Among them, atoms with small ionic radius tend to occupy 4f crystal positions, while atoms with large ionic radius tend to occupy 4g crystal positions. Figure 4 , about R from modified material 60 2 Ce and Ce, Ce with a small ionic radius tends to occupy the 4f crystal position, while Ce with a large ionic radius tends to occupy the 4f crystal position. 2 It is easy to occupy the 4g crystal position. From this point of view, R2 Preferably, it is one or more elements selected from the group consisting of Gd, Tb, Dy and Ho.

[0125] R occupies the 4f crystal position of the shell 14 2 The proportions of Ce and R can be expressed based on the molar ratio. 2 4f and Ce 4f In addition, R occupies the 4g crystal position of the shell 14 2 The proportions of R and Ce can be expressed based on the molar ratio. 2 4g and Ce 4g In this case, the rare earth magnet 100 of the present disclosure satisfies the following relationships (1) and (2).

[0126] 0.44≤R 2 4g / (R 2 4f +R 2 4g )≤0.70 (1)

[0127] 0.04≤(Ce 4f +Ce 4g ) / (R 2 4f +R 2 4g ) (2)

[0128] R 2 4g / (R 2 4f +R 2 4g ) is 0.44 or more, then in the shell 14, R 2 Most of them occupy the 4g crystal position, and the anisotropic magnetic field of the main phase 10 as a whole is increased, resulting in an increase in coercive force. From this point of view, R 2 4g / (R 2 4f +R 2 4g ) may be 0.45 or more, 0.46 or more, 0.47 or more, 0.48 or more, 0.49 or more, or 0.50 or more. 2 4g / (R 2 4f +R 2 4g ) is less than 0.70, Ce occupying the 4f crystal position in the shell portion 14 will not be excessively present, so that R 2 Most of them occupy the 4g crystal position, and as a result, they can maintain the same2 The coercivity increases with the amount used. 2 4g / (R 2 4f +R 2 4g ) can be less than 0.65, less than 0.64, less than 0.63, less than 0.62, less than 0.61, less than 0.60, less than 0.59, less than 0.58, less than 0.57, less than 0.56, less than 0.55, less than 0.54, less than 0.53, less than 0.52 or less than 0.51.

[0129] In addition, in the shell 14, R 2 Preferentially occupying the 4g crystal position, relative to R 2 A certain amount of Ce is required. Therefore, in the shell 14, (Ce 4f +Ce 4g ) / (R 2 4f +R 2 4g ) needs to be 0.04 or more. From this point of view, (Ce 4f +Ce 4g ) / (R 2 4f +R 2 4g ) can be 0.06 or more, 0.11 or more, 0.13 or more, 0.15 or more, 0.20 or more, 0.25 or more, 0.27 or more, or 0.30 or more, and can be 2.50 or less, 2.03 or less, 2.00 or less, 1.70 or less, 1.66 or less, 1.50 or less, 1.47 or less, 1.14 or less, 1.10 or less, 1.00 or less, 0.84 or less, 0.80 or less, 0.55 or less, 0.52 or less, 0.50 or less, 0.45 or less, 0.43 or less, 0.40 or less, or 0.37 or less.

[0130] <Nuclear Department>

[0131] As described above, the core portion 12 has the same composition as the main phase 10 of the rare earth magnet precursor 50 . Therefore, the composition of the core portion 12 represents the properties of the rare earth magnet precursor 50 .

[0132] If R 2 The molar ratio of R in the shell portion 14 is higher than that in the core portion 12, and 2 4g / (R 2 4f +R 2 4g ) and (Ce 4f +Ce4g ) / (R 2 4f +R 2 4g ) satisfies the relationship between (1) and (2) above, the composition of the core portion 12 is not particularly limited. This means that when manufacturing the rare earth magnet 100 disclosed in the present invention, the composition of the rare earth magnet precursor 50 is not particularly limited. The rare earth magnet precursor 50 is described in the "Manufacturing Method". However, by determining the composition of the core portion 12, the specific magnetic properties of the rare earth magnet 100 disclosed in the present invention (the rare earth magnet after the modified material 60 is diffused and plated) can be improved, and the amount of Y and light rare earth elements used can be increased while maintaining the magnetic properties, thereby seeking to reduce costs. They are described as rare earth magnets of the first to third modes.

[0133] <First Method>

[0134] The rare earth magnet of the first embodiment is as follows:

[0135] R 1 Ce, Nd and R 2 One or more elements selected from Y and rare earth elements as essential elements,

[0136] T is one or more transition elements which are one or more elements selected from Fe and Co as essential elements,

[0137] In the core, the core as a whole R 1 The total molar ratio of Y, Sc, La and Ce is less than 0.1.

[0138] In the core portion, the molar ratio of Co is less than 0.1 based on T of the entire core portion, and

[0139] Satisfy 0.47≤R 2 4g / (R 2 4f +R 2 4g )≤0.54.

[0140] The rare earth magnet of the first embodiment is obtained by using a rare earth magnet precursor mainly containing Nd and having low contents of Y, light rare earth elements, and Co. The rare earth magnet of the first embodiment has an excellent balance between residual magnetization and coercive force.

[0141] In the rare earth magnet of the first type, R 1 Ce, Nd and R 2 One or more elements selected from Y and rare earth elements as essential elements. "Essential elements" means that elements other than the target elements may be included within the limit that the effects of the rare earth magnet and the manufacturing method thereof disclosed in the present invention are not impaired. That is, "Ce, Nd and R2 "Essential elements" means that R 1 May contain Ce, Nd and R 2 Typically, R 1 Ce, Nd and R 2 The total amount can be 80 atomic % or more, 90 atomic % or more, 95 atomic % or more, 98 atomic % or more, or 99 atomic % or more, or 100 atomic %. Nd mainly comes from the rare earth magnet precursor, Ce and R 2 Mainly from modified materials. Part or all of Nd can also be replaced by Pr.

[0142] T is one or more transition elements with one or more elements selected from Fe and Co as essential elements. "Essential elements" means that elements other than the target element may be included within the limit that the effect of the rare earth magnet and the manufacturing method thereof disclosed in the present invention is not impaired. That is, the so-called "T is one or more elements selected from Fe and Co as essential elements" means that T may contain transition elements other than Fe and Co within the limit that the effect of the rare earth magnet and the manufacturing method thereof disclosed in the present invention is not impaired. Typically, the total of one or more elements selected from Fe and Co in T may be 80 atomic % or more, 90 atomic % or more, 95 atomic % or more, 98 atomic % or more, or 99 atomic % or more, or 100 atomic %. As transition elements other than Fe and Co, for example, Ga, Al and Cu can be mentioned. These elements are mainly present in the grain boundary phase 20, but a part of them may also be present in the main phase 10 in an interstitial or substitutional type.

[0143] In the rare earth magnet of the first embodiment, the core portion is R 1 Based on the total molar ratio of Y, Sc, La and Ce, the total molar ratio of Y, Sc, La and Ce can be less than 0.10, less than 0.05 or less than 0.03, or 0. In addition, in the core part, based on the T of the entire core part, the molar ratio of Co can be less than 0.10, less than 0.05 or less than 0.03, or 0. As described above, in the core part, Y, Sc, La, Ce and Co are in a small amount, which come from the rare earth magnet precursor. Such a rare earth magnet precursor has an excellent balance between residual magnetization and coercive force, and the coercive force can be further improved by diffusing and plating the modifying material therein.

[0144] In the rare earth magnet of the first aspect, 0.47≤R 2 4g / (R 2 4f +R 2 4g )≤0.54. By satisfying this point, the coercive force can be particularly improved. From this point of view, R2 4g / (R 2 4f +R 2 4g ) may be 0.48 or more or 0.50 or more, and may be 0.53 or less or 0.52 or less.

[0145] <Method 2>

[0146] The second embodiment of the rare earth magnet is as follows:

[0147] R 1 Ce, La, Nd and R 2 One or more elements selected from Y and rare earth elements as essential elements,

[0148] T is one or more transition elements which are one or more elements selected from Fe and Co as essential elements,

[0149] In the core, the core as a whole R 1 As a basis, the total molar ratio of Y, Sc and Ce is less than 0.1, and the molar ratio of La is 0.01 to 0.20,

[0150] In the core portion, the molar ratio of Co is 0.1 to 0.4 based on T of the entire core portion, and

[0151] Satisfy 0.50≤R 2 4g / (R 2 4f +R 2 4g )≤0.60.

[0152] The rare earth magnet of the second embodiment is obtained using a rare earth magnet precursor containing La and Co. In the rare earth magnet of the second embodiment, the main phase becomes unstable when La is contained, but the main phase is stabilized by the coexistence of La and Co, and the reduction of residual magnetization can be suppressed even when cheap La is used.

[0153] In the rare earth magnet of the second embodiment, R 1 Ce, La, Nd and R 2 One or more elements selected from Y and rare earth elements as essential elements. "Essential elements" means that elements other than the target elements may be included within the limit that the effects of the rare earth magnet and the manufacturing method thereof disclosed in the present invention are not impaired. That is, "Ce, La, Nd and R 2 "Essential elements" means that R 1 May contain Ce, La, Nd and R 2 Typically, R1 Among Ce, La, Nd and R 2 The total amount can be 80 atomic % or more, 90 atomic % or more, 95 atomic % or more, 98 atomic % or more, or 99 atomic % or more, or 100 atomic %. La and Nd mainly come from the rare earth magnet precursor, Ce and R 2 Mainly from modified materials. Part or all of Nd can be replaced by Pr.

[0154] T is one or more transition elements with one or more elements selected from Fe and Co as essential elements. "Essential elements" means that elements other than the target element may be included within the limit that the effect of the rare earth magnet and the manufacturing method thereof disclosed in the present invention is not impaired. That is, the so-called "T is one or more elements selected from Fe and Co as essential elements" means that T may contain transition elements other than Fe and Co within the limit that the effect of the rare earth magnet and the manufacturing method thereof disclosed in the present invention is not impaired. Typically, the total of one or more elements selected from Fe and Co in T can be 80 atomic % or more, 90 atomic % or more, 95 atomic % or more, 98 atomic % or more, or 99 atomic % or more, or 100 atomic %. As transition elements other than Fe and Co, for example, Ga, Al and Cu can be mentioned. These elements are mainly present in the grain boundary phase 20, but a part of them may also be present in the main phase 10 in an interstitial or substitutional type.

[0155] In the rare earth magnet of the second embodiment, in the core portion, R 1 As a reference, the total molar ratio of Y, Sc and Ce may be less than 0.1, 0.05 or less, 0.03 or less, or 0. 1 Based on T of the core as a whole, the molar ratio of Co in the core portion can be 0.10 or more, 0.15 or more, 0.20 or less, 0.35 or less, 0.30 or less, or 0.25 or less. As described above, the coexistence of La and Co in the core portion comes from the rare earth magnet precursor. This rare earth magnet precursor can suppress the decrease in residual magnetization even if cheap La is used, and the coercive force can be improved by diffusing and plating modified materials therein.

[0156] In the rare earth magnet of the second embodiment, 0.50≤R 2 4g / (R 2 4f +R 2 4g)≤0.60. By satisfying this point, the coercive force can be particularly improved. From this point of view, R 2 4g / (R 2 4f +R 2 4g ) may be 0.52 or more, 0.54 or more, or 0.56 or more, and may be 0.59 or less, 0.58 or less, or 0.57 or less.

[0157] <Third Method>

[0158] The rare earth magnet of the third embodiment is as follows:

[0159] R 1 Ce, Nd and R 2 One or more elements selected from Y and rare earth elements as essential elements,

[0160] T is one or more transition elements which are one or more elements selected from Fe and Co as essential elements,

[0161] In the core, the core as a whole R 1 The total molar ratio of Y, Sc, La and Ce is 0.10 to 0.90.

[0162] In the core portion, the molar ratio of Co is 0.40 or less based on T of the entire core portion, and

[0163] Satisfy 0.44≤R 2 4g / (R 2 4f +R 2 4g )≤0.51.

[0164] The third type of rare earth magnet uses a rare earth magnet precursor containing a light rare earth element, thereby reducing the amount of Nd used while maintaining the desired residual magnetization and coercive force.

[0165] In the rare earth magnet of the third embodiment, R 1 Ce, Nd and R 2 One or more elements selected from Y and rare earth elements as essential elements. "Essential elements" means that elements other than the target elements may be included within the limit that the effects of the rare earth magnet and the manufacturing method thereof disclosed in the present invention are not impaired. That is, "Ce, Nd and R 2 "Essential elements" means that R 1 May contain Ce, Nd and R 2 Typically, R 1Among Ce, Nd and R 2 The total amount may be 80 atomic % or more, 90 atomic % or more, 95 atomic % or more, 98 atomic % or more, or 99 atomic % or more, or 100 atomic %. Nd mainly comes from the rare earth magnet precursor, and R 2 Mainly from the modified material. Ce comes from both the rare earth magnet precursor and the modified material.

[0166] T is one or more transition elements with one or more elements selected from Fe and Co as essential elements. "Essential elements" means that elements other than the target element may be included within the limit that the effect of the rare earth magnet and the manufacturing method thereof disclosed in the present invention is not impaired. That is, the so-called "T is one or more elements selected from Fe and Co as essential elements" means that T may contain transition elements other than Fe and Co within the limit that the effect of the rare earth magnet and the manufacturing method thereof disclosed in the present invention is not impaired. Typically, the total of one or more elements selected from Fe and Co in T can be 80 atomic % or more, 90 atomic % or more, 95 atomic % or more, 98 atomic % or more, or 99 atomic % or more, or 100 atomic %. As transition elements other than Fe and Co, for example, Ga, Al and Cu can be mentioned. These elements are mainly present in the grain boundary phase 20, but a part of them may also be present in the main phase 10 in an interstitial or substitutional type.

[0167] In the rare earth magnet of the third embodiment, in the core portion, R 1 Based on the total molar ratio of Y, Sc, La and Ce, the total molar ratio can be 0.10 or more, 0.20 or more, 0.30 or more, 0.40 or more or 0.50 or more, and can be 0.90 or less, 0.80 or less, 0.70 or less or 0.60 or less. In addition, in the core part, based on the T of the entire core part, the molar ratio of Co can be 0.40 or less, 0.30 or less, 0.20 or less or 0.10 or less, and can also be 0. In this way, by using the rare earth magnet precursor that actively uses light rare earth elements and reduces the amount of Nd used, the coercive force can be further improved by diffusing and plating the modified material therein while maintaining the residual magnetization and coercive force.

[0168] In the rare earth magnet of the third embodiment, R 2 4g / (R 2 4f +R 2 4g ) is 0.44 or more, 0.45 or more, 0.46 or more, or 0.47 or more, and R 2 4g / (R 2 4f +R 2 4g) is 0.51 or less, 0.50 or less, 0.49 or less, or 0.48 or less, and improvement in coercive force can be recognized.

[0169] <Sub-shell>

[0170] The rare earth magnet disclosed in the present invention may optionally have a subshell portion. This will be described using the accompanying drawings. Figure 5 This is an explanatory diagram schematically showing an example of the structure of an embodiment of the rare earth magnet of the present disclosure having a sub-shell portion. In this embodiment of the rare earth magnet 100 of the present disclosure, a sub-shell portion 16 is provided between the core portion 12 and the shell portion 14 .

[0171] The secondary shell part comes from the diffusion and infiltration of the pre-modified material. The pre-modified material contains at least R 4 . R 4 is one or more elements selected from Pr, Nd, Pm, Sm and Eu. 4 The modified material (containing at least R 2 Before diffusion-plating the modifying materials (such as Ce and Ce), a pre-modifying material is diffused-plated inside the rare earth magnet precursor.

[0172] The secondary shell part comes from the diffusion plating of the pre-modified material, so the R 4 The molar ratio is higher than that of R 4 The molar ratio of R in the secondary shell 4 The molar ratio of R 4 The difference in molar ratio can be, for example, 0.01 or more, 0.05 or more, 0.10 or more, 0.11 or more, 0.12 or more, 0.13 or more, 0.14 or more, or 0.15 or more, and can be 0.50 or less, 0.45 or less, 0.41 or less, 0.40 or less, 0.38 or less, 0.37 or less, 0.36 or less, 0.34 or less, 0.32 or less, 0.30 or less, 0.29 or less, 0.28 or less, 0.27 or less, 0.26 or less, 0.24 or less, 0.22 or less, or 0.20 or less. This is because a portion of the rare earth elements present in the peripheral portion of the main phase of the single phase is exchanged with a portion of the rare earth elements of the pre-modified material diffused and infiltrated into the grain boundary phase to form a sub-shell portion. The formation of the sub-shell portion by diffusion and infiltration of the pre-modified material is described in detail in the "Manufacturing Method".

[0173] <Grain boundary phase>

[0174] like Figure 1 As shown in FIG. 1 , the rare earth magnet 100 of the present disclosure includes a grain boundary phase 20 in addition to the main phase 10 described above. The grain boundary phase 20 exists around the main phase 10 .

[0175] The modified material 60 is diffused and infiltrated into the grain boundary phase 20. In addition to the heavy rare earth elements and Ce, the modified material 60 generally contains transition elements other than rare earth elements, such as copper. As a result, in the grain boundary phase 20, not only the content ratio (concentration) of rare earth elements increases, but also the content ratio of non-magnetic elements such as copper increases. Therefore, the grain boundary phase 20 is non-magnetic in most cases. As a result, the grain boundary phase 20 magnetically divides each main phase 10, which helps to improve the coercive force.

[0176] 《Manufacturing method》

[0177] Next, the method for producing the rare earth magnet of the present disclosure will be described.

[0178] The method for manufacturing a rare earth magnet disclosed in the present invention includes a rare earth magnet precursor preparation step and a modified material diffusion and infiltration plating step. In addition, the method for manufacturing a rare earth magnet disclosed in the present invention may optionally include a pre-modified material infiltration step. Each step is described below.

[0179] <Rare earth magnet precursor preparation step>

[0180] A rare earth magnet precursor having a main phase and a grain boundary phase is prepared. The main phase has a molar ratio of R 1 2T 14 B represents the composition. 1 and T as described in "Rare Earth Magnets".

[0181] like Figure 2A As shown, the main phase 10 in the rare earth magnet precursor 50 before the modifying material 60 is diffused and plated is a single phase. In addition, the grain boundary phase 20 exists around the main phase 10 .

[0182] The composition of the rare earth magnet precursor 50 is not particularly limited as long as the rare earth magnet precursor 50 includes the main phase 10 and the grain boundary phase 20. However, it is preferred that the α-Fe phase does not exist in the grain boundary phase 20 as much as possible. For this reason, the grain boundary phase 20 is preferably a so-called R-rich phase. 1 Phase. So-called R-rich 1 Phase refers to the R of the grain boundary phase 20 1 The content ratio (molar ratio) of R is higher than 10 in the main phase. 1 If the grain boundary phase 20 becomes a so-called R-rich 1 If the α-Fe phase exists in the grain boundary phase 20, the diffusion and infiltration of the modifying material 60 is hindered, and the grain boundary phase 20 becomes the so-called R-rich phase. 1 phase, it is possible to avoid hindering the diffusion and permeation of the modifying material 60.

[0183] As the rare earth magnet precursor 50, a known rare earth magnet can be used. Such a rare earth magnet has a composition of R before the modifying material 60 is diffused and plated. 1 2T 14 The composition (overall composition) of the rare earth magnet precursor 50 may be, for example, R 1 p T (100-p-q) B q (wherein 12.0≤p≤20.0 and 5.0≤q≤20.0). T may contain unavoidable impurity elements in addition to the elements described so far. Most of the unavoidable impurity elements are present in the grain boundary phase, but a part of them may be present in the main phase. Furthermore, in this specification, unavoidable impurity elements refer to impurity elements contained in the raw materials of the rare earth magnet, or impurity elements mixed in the manufacturing process, etc., which are unavoidable to contain, or impurity elements that cause a significant increase in manufacturing costs in order to avoid them. For the convenience of manufacturing, impurity elements mixed in the manufacturing process include elements contained within a range that does not affect the magnetic properties.

[0184] In the modifying material diffusion and plating step described later, the modifying material 60 is diffused and plated near the outer periphery of the single-phase main phase 10 of the rare earth magnet precursor 50. Thus, in the rare earth magnet 100 (the rare earth magnet after the modifying material 60 is diffused and plated) of the present disclosure, Figure 2C As shown, the main phase 10 has a core / shell structure. Therefore, as described in "Core" of "Rare Earth Magnet", in the main phase 10 of the rare earth magnet 100 (rare earth magnet after diffusion and infiltration of the modified material 60) of the present disclosure, the composition of the core 12 maintains the composition of the single-phase main phase 10 in the rare earth magnet precursor 50. Therefore, for the composition of the main phase 10 of the rare earth magnet precursor 50, reference can be made to the description of "Core" of "Rare Earth Magnet". The following is a brief description of the rare earth magnet precursor used in the manufacture of the first to third forms of rare earth magnets described in "Core" of "Rare Earth Magnet".

[0185] <Rare Earth Magnet Precursor Used in Manufacturing Rare Earth Magnet of First Embodiment>

[0186] The rare earth magnet precursor used for manufacturing the rare earth magnet of the first embodiment (hereinafter sometimes referred to as "the rare earth magnet precursor of the first embodiment") has a molar ratio of R 1 2T 14 The main phase represented by B may have the following composition.

[0187] R 1One or more elements selected from Y and rare earth elements with Nd as an essential element. "Essential elements" means that elements other than the target element may be included within the limit that the effect of the rare earth magnet and the manufacturing method thereof disclosed in the present invention is not impaired. That is, "Nd as an essential element" means that within the limit that the effect of the rare earth magnet and the manufacturing method thereof disclosed in the present invention is not impaired, R 1 Elements other than Nd may be included. Typically, in R 1 Among them, Nd may be 80 atomic % or more, 90 atomic % or more, 95 atomic % or more, 98 atomic % or more, or 99 atomic % or more, or may be 100 atomic %. A part or all of Nd may be substituted with Pr.

[0188] T is one or more transition elements with one or more elements selected from Fe and Co as essential elements. "Essential elements" means that elements other than the target element may be included within the limit that the effect of the rare earth magnet and the manufacturing method thereof disclosed in the present invention is not impaired. That is, the so-called "T is one or more elements selected from Fe and Co as essential elements" means that T may contain transition elements other than Fe and Co within the limit that the effect of the rare earth magnet and the manufacturing method thereof disclosed in the present invention is not impaired. Typically, the total of one or more elements selected from Fe and Co in T can be 80 atomic% or more, 90 atomic% or more, 95 atomic% or more, 98 atomic% or more, or 99 atomic% or more, or 100 atomic%. As transition elements other than Fe and Co, for example, Ga, Al and Cu can be mentioned. These elements are mainly present in the grain boundary phase, but part of them can also be present in the main phase in an interstitial or substitutional type.

[0189] In addition, R 1 Based on T, the total molar ratio of Y, Sc, La and Ce may be less than 0.10, 0.05 or less, 0.03 or less, or 0. Moreover, based on T, the molar ratio of Co may be less than 0.1, 0.05 or less, 0.03 or less, or 0.

[0190] The rare earth magnet precursor of the first embodiment has the above-mentioned composition, and the rare earth magnet precursor has an excellent balance between residual magnetization and coercive force. In addition, by diffusion-plating the modifying material therein, the rare earth magnet of the present disclosure can further improve the coercive force.

[0191] The composition (overall composition) of the rare earth magnet precursor is, for example, R 1 p T (100-p-q) B q (where 12.0≤p≤20.0 and 5.0≤q≤20.0), R 1The total molar ratio of Y, Sc, La and Ce when the molar ratio of Co when the molar ratio of Y, Sc, La and Ce when the molar ratio of Co when the molar ratio of T when the molar ratio of Co ... 1 The molar ratio of the respective elements of A and T is the same.

[0192] <Rare Earth Magnet Precursor Used in Production of Rare Earth Magnet of Second Embodiment>

[0193] The rare earth magnet precursor used in the production of the rare earth magnet of the second embodiment (hereinafter sometimes referred to as "the rare earth magnet precursor of the second embodiment") has a molar ratio of R 1 2T 14 The main phase represented by B may have the following composition.

[0194] R 1 It is one or more elements selected from Y and rare earth elements with La and Nd as essential elements. "Essential elements" means that elements other than the target elements may be contained within the limit that the effect of the rare earth magnet and the manufacturing method thereof disclosed in the present invention is not impaired. That is, "La and Nd are essential elements" means that within the limit that the effect of the rare earth magnet and the manufacturing method thereof disclosed in the present invention is not impaired, R 1 Elements other than La and Nd may be included. Typically, R 1 The total content of La and Nd may be 80 atomic % or more, 90 atomic % or more, 95 atomic % or more, 98 atomic % or more, or 99 atomic % or more, or 100 atomic %. A part or all of Nd may be substituted with Pr.

[0195] T is one or more transition elements with one or more elements selected from Fe and Co as essential elements. "Essential elements" means that elements other than the target element may be included within the limit that the effect of the rare earth magnet and the manufacturing method thereof disclosed in the present invention is not impaired. That is, the so-called "T is one or more elements selected from Fe and Co as essential elements" means that T may contain transition elements other than Fe and Co within the limit that the effect of the rare earth magnet and the manufacturing method thereof disclosed in the present invention is not impaired. Typically, the total of one or more elements selected from Fe and Co in T can be 80 atomic % or more, 90 atomic % or more, 95 atomic % or more, 98 atomic % or more, or 99 atomic % or more, or 100 atomic %. As transition elements other than Fe and Co, for example, Ga, Al and Cu can be mentioned. These elements are mainly present in the grain boundary phase 20, but a part of them may also be present in the main phase 10 in an interstitial or substitutional type.

[0196] In addition, R 1 Based on R1 Based on T, the molar ratio of La may be 0.01 or more, 0.02 or more, 0.03 or more, 0.04 or more, or 0.05 or more, and may be 0.20 or less, 0.15 or less, 0.10 or less, 0.08 or less, or 0.06 or less. In addition, based on T, the molar ratio of Co may be 0.10 or more, 0.15 or more, or 0.20 or more, and may be 0.40 or less, 0.35 or less, 0.30 or less, or 0.25 or less.

[0197] The rare earth magnet precursor of the second embodiment has the above-mentioned composition, and even if inexpensive La is used, the rare earth magnet precursor can suppress the reduction of residual magnetization by coexisting with Co. Furthermore, by diffusion-plating the modifying material therein, the rare earth magnet of the present disclosure can improve the coercive force.

[0198] The composition (overall composition) of the rare earth magnet precursor is, for example, R 1 p T (100-p-q) B q (where 12.0≤p≤20.0 and 5.0≤q≤20.0), R 1 The total molar ratio of Y, Sc and Ce and the molar ratio of La and the molar ratio of Co when T is used as the reference are considered to be the same as the above molar ratios for the main phase. This is because it is considered that in the main phase and the grain boundary phase, the R 1 This is because the molar ratio of the elements in A and T is the same.

[0199] <Rare earth magnet precursor used in the production of the rare earth magnet of the third embodiment>

[0200] The rare earth magnet precursor used in the production of the rare earth magnet of the third embodiment (hereinafter sometimes referred to as "the rare earth magnet precursor of the third embodiment") has a molar ratio of R 1 2T 14 The main phase represented by B may have the following composition.

[0201] R 1 Ce and Nd are essential elements, and one or more elements selected from Y and rare earth elements. "Essential elements" means that elements other than the target elements may be included within the limit that the effect of the rare earth magnet and the manufacturing method thereof disclosed in the present invention is not impaired. That is, "Ce and Nd are essential elements" means that within the limit that the effect of the rare earth magnet and the manufacturing method thereof disclosed in the present invention is not impaired, R 1 Elements other than Ce and Nd may be included. Typically, R 1The total amount of Ce and Nd may be 80 atomic % or more, 90 atomic % or more, 95 atomic % or more, 98 atomic % or more, or 99 atomic % or more, or 100 atomic %. A part or all of Nd may be substituted with Pr.

[0202] T is one or more transition elements with one or more elements selected from Fe and Co as essential elements. "Essential elements" means that elements other than the target element may be included within the limit that the effect of the rare earth magnet and the manufacturing method thereof disclosed in the present invention is not impaired. That is, the so-called "T is one or more elements selected from Fe and Co as essential elements" means that T may contain transition elements other than Fe and Co within the limit that the effect of the rare earth magnet and the manufacturing method thereof disclosed in the present invention is not impaired. Typically, the total of one or more elements selected from Fe and Co in T can be 80 atomic % or more, 90 atomic % or more, 95 atomic % or more, 98 atomic % or more, or 99 atomic % or more, or 100 atomic %. As transition elements other than Fe and Co, for example, Ga, Al and Cu can be mentioned. These elements are mainly present in the grain boundary phase 20, but a part of them may also be present in the main phase 10 in an interstitial or substitutional type.

[0203] R 1 Based on T, the total molar ratio of Y, Sc, La and Ce can be 0.10 or more, 0.20 or more, 0.30 or more, 0.40 or more or 0.50 or more, and can be 0.90 or less, 0.80 or less, 0.70 or less or 0.60 or less. Moreover, based on T, the molar ratio of Co can be 0.40 or less, 0.30 or less, 0.20 or less or 0.10 or less, and can also be 0.

[0204] The third embodiment uses a rare earth magnet precursor having the above-mentioned composition, that is, a rare earth magnet precursor in which light rare earth elements are actively used and the amount of Nd used is reduced, and diffuses and plates a modifying material therein while maintaining the residual magnetization and coercive force, thereby further improving the coercive force.

[0205] The composition (overall composition) of the rare earth magnet precursor is, for example, R 1 p T (100-p-q) B q (where 12.0≤p≤20.0 and 5.0≤q≤20.0), R 1 The total molar ratio of Y, Sc, La and Ce based on T and the molar ratio of Co based on T are considered to be the same as the above molar ratio of the main phase. This is because in the main phase and the grain boundary phase, it is considered that the R 1 The molar ratio of the respective elements of A and T is the same.

[0206] <Method for producing rare earth magnet precursor>

[0207] There is no particular limitation on the method for producing the rare earth magnet precursor. Typically, the following production methods can be cited. A molten metal having the composition (overall composition) of the rare earth magnet precursor is cooled to obtain a magnetic ribbon. The magnetic ribbon is crushed to obtain a magnetic powder. The magnetic powder is pressed into powder to obtain a powder compact in a magnetic field. The powder compact is then sintered without pressure to obtain a rare earth magnet precursor. In addition, the magnetic ribbon can be used as a rare earth magnet precursor without sintering, or the magnetic powder can be used as a rare earth magnet precursor.

[0208] The cooling rate of the molten metal having the composition (overall composition) of the rare earth magnet precursor can be, for example, 1 to 1000°C / s. If cooled at this rate, a magnetic ribbon having a main phase with an average particle size of 1 to 20 μm can be obtained. The main phase with such an average particle size is difficult to coarsen during the pressureless sintering of the magnetic powder and the diffusion and infiltration of the modified material. Therefore, it is believed that the average particle size of the main phase in the rare earth magnet disclosed in the present invention (the rare earth magnet after diffusion and infiltration of the modified material) is roughly the same as the average particle size of the main phase in the magnetic powder. For elements that may be lost in the process of obtaining the magnetic ribbon, the amount of loss can be predicted.

[0209] There is no particular limitation on the method for cooling the molten metal having the composition (overall composition) of the rare earth magnet precursor. From the viewpoint of obtaining the above cooling rate, for example, a strip casting method and a book mold casting method can be cited. From the viewpoint of less segregation of the rare earth magnet precursor, a strip casting method is preferred.

[0210] As a method for pulverizing the magnetic ribbon, for example, there can be mentioned a method of coarsely pulverizing the magnetic ribbon and then further pulverizing it with a jet mill, etc. As a method for coarse pulverization, for example, there can be mentioned a method using a hammer mill, a method of hydrogen embrittlement of the magnetic ribbon, and a combination thereof.

[0211] The molding pressure during the compaction of the magnetic powder can be, for example, 50 MPa or more, 100 MPa or more, 200 MPa or more, or 300 MPa or more, and can be 1000 MPa or less, 800 MPa or less, or 600 MPa or less. The applied magnetic field can be 0.1 T or more, 0.5 T or more, 1.0 T or more, 1.5 T or more, or 2.0 T or more, and can be 10.0 T or less, 8.0 T or less, 6.0 T or less, or 4.0 T or less. In this way, if the magnetic powder is compacted while applying a magnetic field, anisotropy can be imparted to the rare earth magnet disclosed in the present invention.

[0212] The sintering temperature of the powder compact may be, for example, 900° C. or more, 950° C. or more, or 1000° C. or more, and may be 1100° C. or less, 1050° C. or less, or 1040° C. or less. The sintering time may be, for example, 1 hour or more, 2 hours or more, 3 hours or more, or 4 hours or more, and may be 24 hours or less, 18 hours or less, 12 hours or less, or 6 hours or less. In order to suppress oxidation of the powder compact during sintering, the sintering atmosphere is preferably an inert gas atmosphere. The inert gas atmosphere includes a nitrogen atmosphere.

[0213] <Modified material diffusion plating process>

[0214] Make it contain at least R 2 The modified material containing Ce and R is diffused and plated into the interior of the rare earth magnet precursor. 2 and Ce, and will not coarsen the main phase of the rare earth magnet precursor, and can diffuse and infiltrate the modified material into the interior of the rare earth magnet precursor. The composition of the modified material is not particularly limited. Typically, the modified material contains at least R 2 and Ce, and contains transition elements other than rare earth elements. If the modified material is such a composition, the melting point of the modified material can be made lower than R 2 and Ce, can diffuse and infiltrate the modifying material into the interior of the rare earth magnet precursor at a relatively low temperature, and can avoid coarsening of the main phase during diffusion and infiltration.

[0215] The composition of the modified material may be, for example, (R 2 (1-r-s) Ce r R 3 s ) (1-t) M 1 t The composition represented by R 3 Is selected from R 2 and rare earth elements other than Ce and one or more elements of Y. 1 It is transition elements and inevitable impurity elements other than Y and rare earth elements. 1 YesR 1 Transition elements and unavoidable impurity elements other than M 1 Preferably with R 2 and Ce, especially with R 2 Alloying to make the melting point of the modified material lower than R 2 The melting point of the element. As such M 1 , for example, one or more elements selected from Cu, Al, Co and Fe. From the viewpoint of lowering the melting point of the modified material, M 1 Cu is preferred.

[0216] When the Ce content ratio (molar ratio) r is 0.05 or more, Ce occupies the 4f crystal position, R 2 Occupies the 4g crystal position, which contributes to the improvement of coercivity. From this point of view, r can be 0.10 or more, 0.20 or more, or 0.30 or more. If r is 0.90 or less, the Ce content ratio will not be excessive, and R 2 The existence ratio of R is relatively reduced, resulting in a decrease in coercivity. From this point of view, r can be less than 0.80, less than 0.70, less than 0.60, less than 0.50 or less than 0.40. The modified material is allowed to contain R 3 , that is, it is allowed to contain R 2 Rare earth elements other than Ce and Y. 3 The content ratio (molar ratio) s may be 0.30 or less, 0.20 or less, 0.10 or less, or 0.05 or less, or may be 0. In order to make the diffusion and permeation temperature of the modifying material a temperature at which the main phase can be prevented from coarsening, M may be appropriately determined. 1 The content ratio (molar ratio) t. t can be greater than 0, greater than 0.10, greater than 0.20 or greater than 0.30, and can be less than 0.90, less than 0.80, less than 0.70, less than 0.60, less than 0.50 or less than 0.40. When t is 0, it means that the modified material is essentially only a rare earth element, and such a modified material is suitable for diffusion and infiltration of the modified material, for example, a vapor phase method. The diffusion and infiltration method of the modified material such as the vapor phase method will be described later.

[0217] As for the manufacturing method of the modified material, as long as the modified material of the above composition can be obtained, there is no particular restriction on the manufacturing method of the modified material. As a manufacturing method of the modified material, for example, a method of obtaining a thin strip by liquid quenching method or thin strip continuous casting method etc. can be cited for the molten metal having the modified material composition. In these methods, since the molten metal is quenched, the segregation of the modified material is less. In addition, as a manufacturing method of the modified material, for example, a molten metal having the modified material composition is cast in a casting mold such as a book mold. In this method, a large amount of modified material can be obtained relatively easily. In order to reduce the segregation of the modified material, the book mold is preferably made of a material with high thermal conductivity. In addition, it is preferred to perform homogenization heat treatment on the casting material to suppress segregation. In addition, as a manufacturing method of the modified material, a method of loading the raw material of the modified material into a container, arc melting the raw material in the container, cooling the molten material to obtain an ingot can be cited. In this method, even if the melting point of the raw material is high, the modified material can be obtained relatively easily. From the viewpoint of reducing segregation of the reformed material, it is preferred to subject the ingot to a homogenizing heat treatment.

[0218] There is no particular limitation on the method of diffusion-plating the modifying material inside the rare earth magnet precursor, but a method that can avoid coarsening of the main phase is preferred. Typical methods of diffusion-plating the modifying material include: Figure 2A to Figure 2C As shown in the figure, the modifying material 60 is brought into contact with the rare earth magnet precursor 50, heated, and the melt of the modifying material 60 is diffused and infiltrated into the interior of the rare earth magnet precursor 50 (liquid phase method). The modifying material 60 is preferably diffused and infiltrated in an inert gas atmosphere. Thereby, oxidation of the rare earth magnet precursor 50 and the modifying material 60 can be suppressed. The inert gas atmosphere includes a nitrogen atmosphere.

[0219] In the case of diffusion-plating the modified material by the liquid phase method, the diffusion-plating temperature (heating temperature) may be, for example, 750° C. or more, 775° C. or more, or 800° C. or more, and may be 1000° C. or less, 950° C. or less, 925° C. or less, or 900° C. or less. In addition, the diffusion-plating time (heating time) may be, for example, 5 minutes or more, 10 minutes or more, 15 minutes or more, or 30 minutes or more, and may be 180 minutes or less, 150 minutes or less, 120 minutes or less, 90 minutes or less, 60 minutes or less, or 40 minutes or less.

[0220] The diffusion and plating amount of the modified material can be appropriately determined so that the desired amount of R 2 Typically, the modifying material may be 0.1 mol parts or more, 1.0 mol parts or more, 2.0 mol parts or more, 2.5 mol parts or more, or 3.0 mol parts or more, and may be 15.0 mol parts or less, 10.0 mol parts or less, or 5.0 mol parts or less, relative to 100 mol parts of the rare earth magnet precursor.

[0221] As a method for diffusing and infiltrating the modified material into the rare earth magnet precursor, in addition to the above-mentioned liquid phase method, a gas phase method can also be cited. In the gas phase method, the modified material is vaporized in a vacuum and diffused and infiltrated into the rare earth magnet precursor. When the modified material is diffused and infiltrated by the gas phase method, the composition of the modified material is, for example, a molar ratio of (R 2 (1-r-s) Ce r R 3 s ) (1-t) M 1 t In the case of a composition represented by , t=0 is preferred. Thus, M remaining in the grain boundary phase can be 1 Minimizing the content of Mg helps to increase the residual magnetization.

[0222] In the case of using a vapor phase method to diffusely plate the modified material, the diffusion infiltration temperature can be, for example, 850°C or more, 875°C or more, or 900°C or more, and can be 1000°C or less, 950°C or less, or 925°C or less. As the diffusion infiltration time, it can be 5 minutes or more, 10 minutes or more, 15 minutes or more, or 30 minutes or more, and can be 180 minutes or less, 150 minutes or less, 120 minutes or less, 90 minutes or less, 60 minutes or less, or 40 minutes or less. The diffusion infiltration amount of the modified material can be based on the situation of the liquid phase method.

[0223] <Preliminary Modified Material Diffusion Plating Process>

[0224] The method for producing the rare earth magnet disclosed in the present invention may optionally include a preliminary modified material diffusion and infiltration plating step. The preliminary modified material diffusion and infiltration plating step will be described below using the accompanying drawings. Fig. 6A This is an explanatory diagram schematically showing an example of a state in which a preliminary modified material is brought into contact with a rare earth magnet precursor. Figure 6B This is an explanatory diagram schematically showing an example of a state in which a preliminary reforming material is diffused and infiltrated into a grain boundary phase of a rare earth magnet precursor. Figure 6C This is an explanatory diagram schematically showing an example of a state in which a sub-shell is formed in a main phase. Fig.6D This is an explanatory diagram schematically showing an example of a state in which a modifying material is brought into contact with a rare earth magnet precursor having a main phase in which a sub-shell is formed. Fig. 6E This is an explanatory diagram schematically showing an example of a state in which a modifying material is diffused and permeated into a grain boundary phase of a rare earth magnet precursor having a subshell formed in a main phase. Fig. 6F This is an explanatory diagram schematically showing an example of a state in which a core / sub-shell / shell structure is formed in the main phase.

[0225] like Figure 6A to Figure 6F As shown, before the modifying material 60 is diffused and infiltrated into the interior of the rare earth magnet precursor 50, the pre-modified material 62 is diffused and infiltrated into the rare earth magnet precursor 50. That is, Fig. 6A As shown in FIG. 1 , the pre-modified material 62 is brought into contact with the surface of the rare earth magnet precursor 50 having the single-phase main phase 10. When heated in this state, as shown in FIG. Figure 6B As shown, the pre-modified material 62 diffuses and infiltrates into the grain boundary phase 20. Figure 6C As shown, the pre-modified material 62 diffused and infiltrated into the grain boundary phase 20 further diffuses and infiltrates into the periphery of the main phase 10, forming a core portion 12 and a sub-shell portion 16 in the main phase 10. At this time, a part of the rare earth element existing in the periphery of the main phase 10 is exchanged with a part of the rare earth element of the pre-modified material 62 diffused and infiltrated into the grain boundary phase 20, forming the sub-shell portion 16. On the other hand, the core portion 12 maintains the same composition as the single-phase main phase 10.

[0226] like Fig.6DAs shown in FIG. 1 , the modified material 60 is brought into contact with the surface of the rare earth magnet precursor 50 having the main phase 10 formed with the subshell portion 16. When heated in this state, as shown in FIG. Fig. 6E As shown, the modified material 60 diffuses and infiltrates into the grain boundary phase 20. Then, as shown in FIG. Fig. 6F As shown, the modified material 60 diffused and infiltrated into the grain boundary phase 20 is further diffused and infiltrated into the outer periphery of the sub-shell portion 16, forming the sub-shell portion 16 and the shell portion 14. At this time, a part of the rare earth element existing in the outer periphery of the sub-shell portion 16 is exchanged with a part of the rare earth element of the modified material 60 diffused and infiltrated into the grain boundary phase 20, forming the shell portion 14. On the other hand, the sub-shell portion 16 maintains the composition before the modified material 60 is diffused and infiltrated.

[0227] The pre-modified material 62 contains at least R 4 As mentioned above, R 4 is one or more elements selected from Pr, Nd, Pm, Sm and Eu. The pre-modified material preferably reduces R 2 Content. 2 It is a scarce and expensive element, but has a high effect of improving the anisotropic magnetic field. When the element with a high effect of improving the anisotropic magnetic field is present on the outermost surface of the main phase 10, its contribution to improving the coercive force becomes greater. Therefore, in the subshell part, it is preferred that R 2 The content ratio should be as low as possible.

[0228] The addition of the pre-modified material diffusion plating step is particularly effective in the case of a rare earth magnet precursor that uses light rare earth elements and reduces the amount of Nd used, such as the rare earth magnet of the third embodiment. When the amount of light rare earth elements used increases, the residual magnetization and coercive force decrease. However, by making the content of R 4 That is, the diffusion and plating of the pre-modified material of the middle rare earth element can compensate for the reduction of the residual magnetization and the anisotropic magnetic field. Compared with the light rare earth elements, the middle rare earth elements are more scarce and expensive. By making the middle rare earth elements that are beneficial to the residual magnetization and the anisotropic magnetic field more present in the sub-shell part that is closer to the outside than the core part, the residual magnetization and the anisotropic magnetic field can be increased with less middle rare earth elements. In particular, since the anisotropic magnetic field can be increased, it makes a significant contribution to improving the coercive force.

[0229] The composition of the pre-modified material may be, for example, in a molar ratio of (R 4 (1-i) R 5 i ) (1-j) M 2 j The composition represented by R 5 Is selected from R 4 One or more elements other than Y and rare earth elements. 2It is transition elements and inevitable impurity elements other than Y and rare earth elements. 2 YesR 1 Transition elements and unavoidable impurity elements other than M 2 Preferably with R 4 Alloying to make the melting point of the modified material lower than R 4 The melting point of the element. As such M 2 , for example, one or more elements selected from Cu, Al, Co and Fe. From the viewpoint of lowering the melting point of the modified material, M 2 Cu is preferred.

[0230] Pre-modified materials are allowed to contain R 5 That is R 4 Except Y and rare earth elements. 5 The content ratio (molar ratio) i of may be 0.30 or less, 0.20 or less, 0.10 or less, or 0.05 or less, or may be 0. In addition, in order to make the diffusion and permeation temperature of the pre-modified material reach a temperature at which the main phase can be prevented from coarsening, M may be appropriately determined. 2 j may be greater than or equal to 0, greater than or equal to 0.10, greater than or equal to 0.20, or greater than or equal to 0.30, and may be less than or equal to 0.90, less than or equal to 0.80, less than or equal to 0.70, less than or equal to 0.60, less than or equal to 0.50, or less than or equal to 0.40. j being 0 means that the modifying material is substantially only a rare earth element, and in the case of such a modifying material, a vapor phase method, for example, is applicable to diffusion plating of the modifying material.

[0231] There is no particular restriction on the method of diffusion-plating the pre-modified material into the rare earth magnet precursor, but preferably the method can avoid the coarsening of the main phase. As a diffusion-plating method for the pre-modified material, a typical method is a liquid phase method. It is preferred to diffuse-plating the pre-modified material in an inert gas atmosphere. Thus, the oxidation of the rare earth magnet precursor and the pre-modified material can be suppressed. The inert gas atmosphere includes a nitrogen atmosphere.

[0232] When the pre-modified material is diffused and plated by the liquid phase method, the diffusion and plating temperature (heating temperature) can be, for example, 750° C. or more, 775° C. or more, or 800° C. or more, and can be 1000° C. or less, 950° C. or less, 925° C. or less, or 900° C. or less. The diffusion and plating time (heating time) can be 5 minutes or more, 10 minutes or more, 15 minutes or more, or 30 minutes or more, and can be 240 minutes or less, 180 minutes or less, 165 minutes or less, 150 minutes or less, 120 minutes or less, 90 minutes or less, 60 minutes or less, or 40 minutes or less.

[0233] The diffusion plating amount of the pre-modified material can be appropriately determined so that the expected amount of R 4Typically, the amount may be 0.1 mol or more, 1.0 mol or more, 2.0 mol or more, 2.5 mol or more, or 3.0 mol or more, and may be 15.0 mol or less, 10.0 mol or less, or 5.0 mol or less, relative to 100 mol of the rare earth magnet precursor.

[0234] As a method for diffusing and plating the pre-modified material into the rare earth magnet precursor, in addition to the above-mentioned liquid phase method, for example, a gas phase method can be cited. In the gas phase method, the pre-modified material is vaporized in a vacuum, and the pre-modified material is diffused and plating into the rare earth magnet precursor. When the gas phase method is used to diffuse and plating the modified material, the composition of the pre-modified material is, for example, a molar ratio of (R 4 (1-i) R 5 i ) (1-j) M 2 j In the case of a composition represented by , j = 0 is preferred. This allows the M remaining in the grain boundary phase to be 2 Minimizing the content helps to increase the residual magnetization.

[0235] In the case of using a vapor phase method to diffusely plate the pre-modified material, the diffusion and plating temperature can be, for example, 850° C. or more, 875° C. or more, or 900° C. or more, and can be 1000° C. or less, 950° C. or less, or 925° C. or less. The diffusion and plating time can be 5 minutes or more, 10 minutes or more, 15 minutes or more, or 30 minutes or more, and can be 180 minutes or less, 150 minutes or less, 120 minutes or less, 90 minutes or less, 60 minutes or less, or 40 minutes or less. The diffusion and plating amount of the pre-modified material can be based on the situation of the liquid phase method.

[0236] There is no particular limitation on the method for producing the preliminary modified material as long as the modified material having the above composition can be obtained. In addition, the method for producing the preliminary modified material can refer to the method for producing the modified material.

[0237] The rare earth magnet obtained by the manufacturing method described so far has a molar ratio of R 1 p T (100-p-q) B q ·((R 2 (1-r-s) Ce r R 3 s ) (1-t) M 1 t ) m ·(R 4 (1-i) R 5i ) (1-j) M 2 j ) n In this formula, R 1 p T (100-p-q) B q From rare earth magnet precursors, (R 2 (1-r-s) Ce r R 3 s ) (1-t) M 1 t from modified materials, and (R 4 (1-i) R 5 i ) (1-j) M 2 j From the pre-modified material. In addition, m and n correspond to the diffusion and plating amount (in moles) of the modified material and the pre-modified material relative to 100 moles of the rare earth magnet precursor, respectively.

[0238] <Transformation>

[0239] In addition to the contents described so far, the rare earth magnet and the method for producing the same disclosed in the present invention can be subjected to various modifications within the scope of the contents described in the claims. For example, as a modified material, a material containing at least R 2 and Ce fluoride, and the modified material is diffused and plated into the interior of the rare earth magnet precursor by a vapor phase method. As a result, the rare earth magnet disclosed in the present invention as a whole can reduce the content ratio of rare earth elements and rare earth magnets other than iron group elements, and can improve the residual magnetization. In addition, before the diffusion and plating of the modified material, the rare earth magnet precursor can be homogenized and heat treated at 800-1050°C for 1-24 hours. In this way, segregation in the rare earth magnet precursor can be suppressed. In addition, before and after the diffusion and plating of the modified material, a so-called optimized heat treatment can be performed. As conditions for the optimized heat treatment, for example, it is possible to keep at 850-1000°C for 50-300 minutes, and then cool to 450-700°C at a rate of 0.1-5.0°C / min. By optimizing the heat treatment, the residual magnetization and coercive force can be improved.

[0240] [Example]

[0241] The rare earth magnet and the method for producing the same according to the present disclosure are described in more detail below by way of examples and comparative examples. Note that the rare earth magnet and the method for producing the same according to the present disclosure are not limited to the conditions used in the following examples.

[0242] 《Sample Preparation》

[0243] Samples of Examples 1 to 18, Comparative Examples 1 to 3, and Reference Examples 1 to 3 were prepared in the following order.

[0244] <Preparation of Samples of Example 1>

[0245] Prepare the overall composition in terms of molar ratio (Nd 0.81 Pr 0.19 ) 14 (Fe 0.99 Co 0.01 ) 79.3 B 5.9 Ga 0.4 Al 0.2 Cu 0.2 The rare earth magnet precursor is prepared based on a magnetic thin strip, which is prepared by a thin strip continuous casting method by casting a rare earth magnet having a molar ratio of (Nd 0.81 Pr 0.19 ) 14 (Fe 0.99 Co 0.01 ) 79.3 B 5.9 Ga 0.4 Al 0.2 Cu 0.2 The magnetic powder is hydrogen-crushed and then crushed with a jet mill to obtain a magnetic powder. The magnetic powder is pressed while applying a 2T magnetic field to obtain a pressed powder body. Then, the pressed powder body is pressure-free sintered at 1050°C for 4 hours to obtain a rare earth magnet precursor. The main phase composition of the rare earth magnet precursor is (Nd 0.81 Pr 0.19 )2(Fe 0.99 Co 0.01 ) 14 B. Most of Ga, Al and Cu in the melt are present in the grain boundary phase, and the contents of Ga, Al and Cu in the main phase are below the detection limit. In addition, the average grain size of the main phase is 4.9 μm.

[0246] The modified material was diffused and plated into the rare earth magnet precursor obtained as described above to obtain the sample of Example 1. The composition of the modified material is (Tb 0.9 Ce 0.1 ) 0.7 Cu 0.3 The diffusion plating temperature was 950° C. and the diffusion plating time was 15 minutes. 2.5 mol parts of the modifying material were diffusion plated into 100 mol parts of the rare earth magnet precursor.

[0247] <Preparation of Samples of Examples 2 to 5>

[0248] For Examples 2 to 5, the compositions of the modified materials are (Tb0.8 Ce 0.2 ) 0.7 Cu 0.3 ,(Tb 0.7 Ce 0.3 ) 0.7 Cu 0.3 ,(Tb 0.6 Ce 0.4 ) 0.7 Cu 0.3 and (Tb 0.4 Ce 0.6 ) 0.7 Cu 0.3 , Examples 2 to 5 were prepared in the same manner as Example 1 except for the above. Note that the samples of Examples 1 to 5 correspond to the rare earth magnets of the first embodiment.

[0249] <Preparation of Samples of Comparative Example 1>

[0250] The composition of the modified material is Tb 0.7 Cu 0.3 , a sample of Comparative Example 1 was prepared in the same manner as in Example 1 except for the above.

[0251] <Preparation of Samples in Reference Example 1>

[0252] The composition of the modified material is Ce 0.7 Cu 0.3 , except for this, the sample of Reference Example 1 was prepared in the same manner as in Example 1.

[0253] <Preparation of Samples of Example 6>

[0254] Prepare the overall composition in terms of molar ratio (Nd 0.77 Pr 0.18 La 0.05 ) 14.4 (Fe 0.8 Co 0.2 ) 79.1 B 5.7 Ga 0.4 Al 0.2 Cu 0.2 The rare earth magnet precursor is prepared based on a magnetic thin strip, which is prepared by a thin strip continuous casting method by casting a rare earth magnet having a molar ratio of (Nd 0.77 Pr 0.18 La 0.05 ) 14.4 (Fe 0.8 Co 0.2 ) 79.1 B 5.7 Ga 0.4 Al 0.2 Cu 0.2The magnetic powder is hydrogen-crushed and then crushed with a jet mill to obtain magnetic powder. The magnetic powder is pressed while applying a 2T magnetic field to obtain a pressed powder body. Then, the pressed powder body is pressure-free sintered at 1050°C for 4 hours to obtain a rare earth magnet precursor. The main phase composition of the rare earth magnet precursor is (Nd 0.77 Pr 0.18 La 0.05 )2(Fe 0.8 Co 0.2 ) 14 B. Most of Ga, Al and Cu in the melt are present in the grain boundary phase, and the contents of Ga, Al and Cu in the main phase are below the detection limit. In addition, the average grain size of the main phase is 5.2 μm.

[0255] The modified material was diffused and plated into the rare earth magnet precursor obtained as described above to obtain the sample of Example 1. The composition of the modified material is (Tb 0.9 Ce 0.1 ) 0.7 Cu 0.3 The diffusion plating temperature was 950° C. and the diffusion plating time was 15 minutes. 2.5 mol of the modified material was diffusion plated into 100 mol of the rare earth magnet precursor.

[0256] <Preparation of Samples of Examples 7 to 11>

[0257] For Examples 7 to 11, the compositions of the modified materials are (Tb 0.7 Ce 0.3 ) 0.7 Cu 0.3 ,(Tb 0.6 Ce 0.4 ) 0.7 Cu 0.3 ,(Tb 0.5 Ce 0.5 ) 0.7 Cu 0.3 ,(Tb 0.4 Ce 0.6 ) 0.7 Cu 0.3 and (Tb 0.3 Ce 0.7 ) 0.7 Cu 0.3 , except for this, samples of Examples 7 to 11 were prepared in the same manner as in Example 6. Note that the samples of Examples 6 to 11 correspond to the rare earth magnets of the second embodiment described above.

[0258] <Preparation of Samples of Comparative Example 2>

[0259] The composition of the modified material is Tb 0.7 Cu0.3 , a sample of Comparative Example 2 was prepared in the same manner as in Example 6 except for the above.

[0260] <Preparation of Samples in Reference Example 2>

[0261] The composition of the modified material is Ce 0.7 Cu 0.3 , except for this, the sample of Reference Example 2 was prepared in the same manner as in Example 6.

[0262] <Preparation of Samples of Example 12>

[0263] Prepare the overall composition in terms of molar ratio (Nd 0.5 Ce 0.375 La 0.125 ) 13.1 Fe 80.5 B6 0.1 Ga 0.3 The rare earth magnet precursor is prepared based on a magnetic thin strip, which is prepared by a thin strip continuous casting method by casting a rare earth magnet having a molar ratio of (Nd 0.5 Ce 0.375 La 0.125 ) 13.1 Fe 80.5 B6 0.1 Ga 0.3 The magnetic powder is hydrogen-crushed and then crushed with a jet mill to obtain magnetic powder. The magnetic powder is pressed while applying a 2T magnetic field to obtain a pressed powder body. Then, the pressed powder body is pressure-free sintered at 1050°C for 4 hours to obtain a rare earth magnet precursor. The main phase composition of the rare earth magnet precursor is (Nd 0.5 Ce 0.375 La 0.125 )2Fe 14 B. Ga and Cu in the melt are mostly present in the grain boundary phase, and the contents of Ga and Cu in the main phase are below the detection limit. In addition, the average grain size of the main phase is 5.0 μm.

[0264] The pre-modified material is diffused and plated into the rare earth magnet precursor obtained as described above. The composition of the pre-modified material is Nd 0.9 Cu 0.1 The diffusion plating temperature was 950°C and the diffusion plating time was 165 minutes. 4.7 mol of the modified material was diffused and infiltrated into 100 mol of the rare earth magnet precursor. The composition of the subshell after the pre-modified material was diffused and infiltrated was (Nd 0.91 Ce 0.08 La 0.01 )2Fe 14 B.

[0265] The modified material is further diffused and plated into the rare earth magnet precursor having the above-mentioned subshell portion to obtain the sample of Example 12. The composition of the modified material is (Tb 0.9Ce0.1 ) 0.7 Cu 0.3 The diffusion plating temperature was 950° C. and the diffusion plating time was 15 minutes. 2.5 mol parts of the modifying material were diffusion plated into 100 mol parts of the rare earth magnet precursor.

[0266] <Preparation of Samples of Examples 13 to 18>

[0267] For Examples 7 to 11, the compositions of the modified materials are (Tb 0.8 Ce 0.2 ) 0.7 Cu 0.3 ,(Tb 0.7 Ce 0.3 ) 0.7 Cu 0.3 ,(Tb 0.6 Ce 0.4 ) 0.7 Cu 0.3 ,(Tb 0.5 Ce 0.5 ) 0.7 Cu 0.3 ,(Tb 0.4 Ce 0.6 ) 0.7 Cu 0.3 and (Tb 0.3 Ce 0.7 ) 0.7 Cu 0.3 , except for this, samples of Examples 13 to 18 were prepared in the same manner as in Example 12. Note that the samples of Examples 12 to 18 correspond to the rare earth magnets of the second embodiment described above.

[0268] <Preparation of Samples of Comparative Example 3>

[0269] The composition of the modified material is Tb 0.7 Cu 0.3 , a sample of Comparative Example 3 was prepared in the same manner as in Example 12 except for the above.

[0270] <Preparation of Samples of Reference Example 3>

[0271] The composition of the modified material is Ce 0.7 Cu 0.3 , except for this, the sample of Reference Example 3 was prepared in the same manner as in Example 12.

[0272] "evaluate"

[0273] The magnetic properties of each sample were measured at 300K using a vibrating sample magnetometer (VSM). The magnetic properties were measured before and after the modified material was diffused and plated. In the case where the pre-modified material was diffused and plated, the magnetic properties were measured before and after the diffusion and plating. In addition, the composition of the shell was analyzed using CS-STEM-EDX (Cs Corrected-Scanning Transmission Electron Microscope-Energy Dispersive X-ray spectroscope; scanning transmission electron microscope with spherical aberration correction function-energy dispersive X-ray spectrometer) to obtain R 2 4g / (R 2 4f+ R 2 4g ) and (Ce 4f +Ce 4g ) / (R 2 4f+ R 2 4g ). During analysis, the electron beam is incident on the sample from the

[110] direction. 1 The 4f and 4g crystal positions are arranged alternately, so the composition of each crystal position can be analyzed with atomic-level resolution.

[0274] The results are shown in Tables 1 to 3. Figure 7 This is a graph showing the relationship between the molar ratio of the modifying material Ce and the coercive force for the samples in Table 1. Figure 8 This is a graph showing the relationship between the molar ratio of the modifying material Ce and the coercive force for the samples in Table 2. Fig. 9 This is a graph showing the relationship between the molar ratio of the modifying material Ce and the coercive force for the samples in Table 3. Fig.10 For the samples in Table 1, R 2 4g / (R 2 4f +R 2 4g ) and coercive force. Fig.11 For the samples in Table 2, R 2 4g / (R 2 4f +R 2 4g ) and coercive force. Fig.12 For the samples in Table 3, R 2 4g / (R 24f +R 2 4g ) and coercive force.

[0275] Table 1-1

[0276]

[0277] Table 1-2

[0278]

[0279] Table 1-3

[0280]

[0281] Table 2-1

[0282]

[0283] Table 2-2

[0284]

[0285] Table 2-3

[0286]

[0287] Table 3-1

[0288]

[0289] Table 3-2

[0290]

[0291] Table 3-3

[0292]

[0293] Table 3-4

[0294]

[0295] Figures 7 to 9 The dotted line is the modified material with Ce molar ratio of 0 (Tb 0.7 Cu 0.3 ) The coercivity value of the sample diffused and plated is the same as that of the modified material with a Ce molar ratio of 1 (Ce 0.7 Cu 0.3 ) is a line connecting the coercivity values ​​of the samples that were diffused and plated. In the past, it was believed that the coercivity decreased as the molar ratio of Ce in the modified material increased. Therefore, it was previously believed that the coercivity decreased along the dotted line. However, when Tb(R 2 ) and Ce coexisting modified materials ((Tb (1-x)Cex) 0.7 Cu 0.3 The sample of the embodiment of diffusion plating in the range of 0<x<1) has a coercive force value above the dotted line. Therefore, it can be understood that the rare earth magnet of the present disclosure has a coercive force value higher than that of the heavy rare earth element (R 2 ) content is higher than predicted. In addition, it can be understood that the rare earth magnet of the present disclosure having such a coercive force satisfies 0.44≤R 2 4g / (R 2 4f +R 2 4g )≤0.70 and 0.04≤(Ce 4f +Ce 4g ) / (R 2 4f +R 2 4g ).

[0296] In addition, from Table 1 and Fig.10 It can be understood that in the rare earth magnet of the first embodiment, 0.47≤R 2 4g / (R 2 4f +R 2 4g )≤0.54, it has a particularly high coercive force. In addition, from Table 2 and Fig.11 It can be understood that in the rare earth magnet of the second embodiment, 0.50≤R 2 4g / (R 2 4f +R 2 4g )≤0.60, it has a particularly high coercive force. Moreover, from Table 3 and Fig.12 It can be understood that in the third type of rare earth magnet, 0.44≤R 2 4g / (R 2 4f +R 2 4g )≤0.51, it has a particularly high coercive force.

[0297] From the above results, the effects of the rare earth magnet and the method for producing the same according to the present disclosure can be confirmed.

Claims

1. A rare earth magnet comprising a main phase and a grain boundary phase existing around the main phase, wherein the composition of the main phase is R 1 2T 14 B means, among which, R 1 is one or more elements selected from Y and rare earth elements, T is one or more transition elements having one or more elements selected from Fe, Co and Ni as essential elements, The main phase has a core portion and a shell portion existing around the core portion, The shell R 2 The molar ratio is higher than that of the core R 2 The molar ratio of R 2 is one or more elements selected from the group consisting of Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu, and, The R occupying the 4f crystal position of the shell 2 The existence ratio of Ce is R 2 4f Ce 4f and the R occupying the 4g crystal position of the shell 2 The existence ratio of Ce is R 2 4g Ce 4g When , the following relationship is satisfied: 0.44≤R 2 4g / (R 2 4f +R 2 4g )≤0.70 and 0.04≤(What 4f +What 4g ) / (R 2 4f +R 2 4g ), A sub-shell portion is provided between the core portion and the shell portion, and The R of the secondary shell 4 The molar ratio is higher than that of the core R 4 The molar ratio of R 4 It is one or more elements selected from Pr, Nd, Pm, Sm and Eu.

2. The rare earth magnet according to claim 1, The R 1 Ce, Nd and R 2 One or more elements selected from Y and rare earth elements as essential elements, The T is one or more transition elements which are one or more elements selected from Fe and Co as essential elements, In the core, the R of the core as a whole 1 The total molar ratio of Y, Sc, La and Ce is less than 0.

10. In the core portion, the molar ratio of Co is less than 0.10 based on T of the entire core portion, and The rare earth magnet satisfies the following relationship: 0.47≤R 2 4g / (R 2 4f +R 2 4g )≤0.54。 3. The rare earth magnet according to claim 1, The R 1 Ce, La, Nd and R 2 One or more elements selected from Y and rare earth elements as essential elements, The T is one or more transition elements which are one or more elements selected from Fe and Co as essential elements, In the core, the R of the core as a whole 1 The total molar ratio of Y, Sc and Ce is less than 0.10, and the molar ratio of La is 0.01 to 0.

20. In the core portion, the molar ratio of Co is 0.10 to 0.40 based on T of the entire core portion, and The rare earth magnet satisfies the following relationship: 0.50≤R 2 4g / (R 2 4f +R 2 4g )≤0.60。 4. The rare earth magnet according to claim 1, The R 1 Ce, Nd and R 2 One or more elements selected from Y and rare earth elements as essential elements, The T is one or more transition elements which are one or more elements selected from Fe and Co as essential elements, In the core, the R of the core as a whole 1 The total molar ratio of Y, Sc, La and Ce is 0.10 to 0.

90. In the core portion, the molar ratio of Co is 0.40 or less based on T of the entire core portion, and The rare earth magnet satisfies the following relationship: 0.44≤R 2 4g / (R 2 4f +R 2 4g )≤0.51。 5. A method for manufacturing a rare earth magnet, which is a method for manufacturing the rare earth magnet according to claim 1, comprising the following steps: A rare earth magnet precursor is prepared, the rare earth magnet precursor comprising a main phase and a grain boundary phase existing around the main phase, wherein the main phase is composed of R 1 2T 14 B means, among which, R 1 is one or more elements selected from Y and rare earth elements, and T is one or more transition elements having one or more elements selected from Fe, Co and Ni as essential elements; and Make it contain at least R 2 and Ce modified materials are diffused and plated into the interior of the rare earth magnet precursor, The method further comprises the following steps: before diffusing and permeating the modified material into the rare earth magnet precursor, diffusing and permeating the pre-modified material into the rare earth magnet precursor, The pre-modified material contains at least R 4 , where R 4 It is one or more elements selected from Pr, Nd, Pm, Sm and Eu.

6. The method for producing a rare earth magnet according to claim 5, In the rare earth magnet precursor, The R 1 is one or more elements selected from Y and rare earth elements with Nd as an essential element, The T is one or more transition elements which are one or more elements selected from Fe and Co as essential elements, With the R 1 The total molar ratio of Y, Sc, La and Ce is less than 0.10, and Based on the T, the molar ratio of Co is less than 0.

10.

7. The method for producing a rare earth magnet according to claim 5, In the rare earth magnet precursor, The R 1 is one or more elements selected from Y and rare earth elements with La and Nd as essential elements, The T is one or more transition elements which are one or more elements selected from Fe and Co as essential elements, With the R 1 The total molar ratio of Y, Sc and Ce is less than 0.10, and the molar ratio of La is 0.01 to 0.20, and Based on the above T, the molar ratio of Co is 0.10 to 0.

40.

8. The method for producing a rare earth magnet according to claim 5, In the rare earth magnet precursor, The R 1 is one or more elements selected from Y and rare earth elements with Ce and Nd as essential elements, The T is one or more transition elements which are one or more elements selected from Fe and Co as essential elements, With the R 1 The total molar ratio of Y, Sc, La and Ce is 0.10 to 0.90, and Based on the above T, the molar ratio of Co is 0.40 or less.

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