Anisotropic magnet and method for manufacturing anisotropic magnet

Abstract

An anisotropic magnet includes an R-T-B based magnet (A) (R represents a rare earth element including Nd and / or Pr, and T represents Fe or Fe and Co. ) in which the amount of rare earth elements contained is more than 12 at% and less than 19 at%; and an R-T-B based magnet (B) (R represents a rare earth element including Nd and / or Pr, and T represents Fe or Fe and Co. ) The amount of rare earth elements contained in the R-T-B magnet (A) is greater than the amount of rare earth elements contained in the R-T-B magnet (A), and the amount of rare earth elements contained in the R-T-B magnet (A) is 19 at% or less.

Description

Technical Field

[0001] The present invention relates to an anisotropic magnet and a method for manufacturing the anisotropic magnet. Background Art

[0002] Patent Document 1 describes a permanent magnet material that has magnetic anisotropy by having the following two regions: a region having a composition of R x (T, M) 100-x (wherein R is a rare earth element, M is a semi-metal, T is a transition metal mainly composed of Fe and / or Co and contains one or more of Zr, Nb, Ti, V, Hf, Ta, and W as essential components, and x is 5 ≤ x < 12 in at%) and having microcrystals with an average particle size of 2 μm or less as the main body; and a region having a composition of R x1 (T, M) 100-x1 (wherein R is a rare earth element, T is a transition metal mainly composed of Fe or Fe and Co, M is a semi-metal mainly composed of B, and x1 is 12 ≤ x1 ≤ 20 in at%) and having microcrystals with an average particle size of 2 μm or less as the main body.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Patent Laid-Open No. 64-42554 Summary of the Invention

[0006] However, the permanent magnet material having magnetic anisotropy described in Patent Document 1 has a problem of low magnetic properties.

[0007] Therefore, an object of the present invention is to provide an anisotropic magnet having excellent magnetic properties.

[0008] An anisotropic magnet according to one aspect of the present invention includes: an R-T-B-based magnet (A) containing more than 12 at% and less than 19 at% of a rare earth element (R represents a rare earth element including Nd and / or Pr, and T represents Fe or Fe and Co); and an R-T-B-based magnet (B) containing more of the rare earth element than the amount of the rare earth element in the above R-T-B-based magnet (A) and containing 19 at% or less of the rare earth element (R represents a rare earth element including Nd and / or Pr, and T represents Fe or Fe and Co).

[0009] Advantages of the Invention

[0010] According to one aspect of the present invention, an anisotropic magnet having excellent magnetic properties can be obtained. Brief Description of the Drawings

[0011] Figure 1 It is a graph showing the demagnetization curves of the magnets produced in the examples and comparative examples. Detailed Description of the Invention

[0012] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the present invention is not limited by this embodiment. In addition, among the constituent elements in the following embodiments, there are elements that can be replaced and easily replaced by those skilled in the art or substantially the same elements.

[0013] <Anisotropic Magnet>

[0014] The anisotropic magnet of the embodiment includes: an R-T-B (boron) -based magnet (A) in which the amount of rare earth elements contained exceeds 12 at% and is less than 19 at% (R represents a rare earth element including Nd (neodymium) and / or Pr (praseodymium), and T represents Fe (iron) or Fe and Co (cobalt)); and an R-T-B -based magnet (B) in which the amount of rare earth elements contained is more than the amount of rare earth elements in the above-mentioned R-T-B -based magnet (A) and the amount of rare earth elements contained is 19 at% or less (R represents a rare earth element including Nd and / or Pr, and T represents Fe or Fe and Co).

[0015] Furthermore, as a measure for saving heavy rare earth elements, as an anisotropic rare earth iron-based bulk magnet having small temperature characteristics and heat resistance at the same time, a hot-worked magnet has attracted attention. When the hot-worked magnet is anisotropized, the grain boundary phase requires a liquid phase component. The liquid phase component is mainly a rare earth component. Therefore, as a composition required for plastic deformation, it is necessary to make the amount of rare earth element R greater than Nd 2 Fe 14 The stoichiometric composition of the B phase (Nd 11.76 Fe 82.36 B 5.88 ), and the amount of rare earth elements is preferably 13 at% or more. However, since a heat history is added during plastic deformation and the coercivity decreases, there is a trade-off relationship between the coercivity and magnetization. Therefore, it has become a further technical problem to increase the magnetization while suppressing the decrease in coercivity.

[0016] In addition, when manufacturing a hot-worked magnet, in order to increase the magnetization, an attempt has also been made to use a magnet having a rare earth element R content less than Nd 2 Fe 14 in the stoichiometric composition of the B phase (R-rich magnet) together with a magnet having a rare earth element R content greater than Nd 2 Fe 14 in the stoichiometric composition of the B phase (T-rich magnet) (for example, Patent Document 1). However, in this case, as in the comparative example described later, the anisotropization is insufficient, and the magnetization decreases together with the coercivity.

[0017] In contrast, if a magnet rich in R includes the above R-T-B magnet (B) and the above R-T-B magnet (A) which is rich in R but has a larger amount of T than the above R-T-B magnet (B), like the anisotropic magnet of the embodiment, the decrease in coercivity is suppressed and the magnetization is increased. Thus, the anisotropic magnet of the embodiment has excellent magnetic properties. It is considered that this is because anisotropization occurs sufficiently when manufacturing the anisotropic magnet of the embodiment. The anisotropic magnet of the embodiment can be manufactured, for example, by hot working while simultaneously using a magnet powder rich in R and a magnet powder rich in R but having a larger amount of T than the former, as described later. In this case, it is considered that anisotropization occurs sufficiently during hot working, and the magnetization can be increased while suppressing the decrease in coercivity.

[0018] It should be noted that the object of Patent Document 1 is "to focus on the fact that the rare earth element R in the R-T-M magnet is 12 at% or more, so that the deformation resistance is small and it is easy to perform press forming and plastic working, and to improve the anti-deformability of the improved R-T-M magnet with R less than 12 at%". The method is "to mix two kinds of powders with R < 12 at% and R ≥ 12 at% and coalesce them to improve the formability and plastic working property". Thereby, it is disclosed that "the characteristics of the whole are improved by the high characteristics of the magnet material with R < 12 at%, and the workability of the whole is improved by the plastic deformability of the magnet material with R ≥ 12 at%". In other words, the object of Patent Document 1 is to provide the following R-T-M magnet material: mixing a magnet powder that forms a soft magnetic phase by making the amount of the rare earth element R less than the stoichiometric composition of the Nd 2 Fe 14 B phase (Nd 11.76 Fe 82.36 B 5.88 ) and is rich in Fe, and a magnet powder that forms a Nd-rich phase by making the amount of the rare earth element R greater than the stoichiometric composition of the Nd 2 Fe 14 B phase, which has a small deformation resistance, is excellent in press forming or plastic working, etc., and can be densified and highly anisotropized.

[0019] However, in the case of mixing a magnet powder with the amount of the rare earth element R less than the stoichiometric composition of the Nd 2 Fe 14 B phase (Nd 11.76 Fe 82.36 B 5.88 ) and rich in Fe and a magnet powder with the amount of the rare earth element R greater than the stoichiometric composition of the Nd 2 Fe 14When magnet powder of the Nd-rich phase is formed by mixing with the stoichiometric composition of the B-phase and then subjected to thermoplastic processing, the anisotropization is insufficient and the magnetic properties deteriorate.

[0020] In the anisotropic magnet of the embodiment, preferably, the amount of the rare earth element contained in the R-T-B-based magnet (A) is 13 at% or more and less than 19 at%, and the amount of the rare earth element contained in the R-T-B-based magnet (B) is more than the amount of the rare earth element in the R-T-B-based magnet (A) and is 19 at% or less. When the amount of the rare earth element is within the above range, plastic deformation occurs sufficiently, and the residual magnetic flux density Br can be further increased. In addition, a decrease in the coercive force can be further suppressed.

[0021] In the R-T-B-based magnet (A) and the R-T-B-based magnet (B), R represents a rare earth element including Nd and / or Pr. Preferably, R contains Nd as an essential component, and more preferably, R is Nd or Nd and Pr. As the rare earth element, it may also include at least one selected from scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu).

[0022] In both the R-T-B-based magnet (A) and the R-T-B-based magnet (B), preferably, when the total amount of Fe and Co is set to 100 at%, the amount of Fe contained is 50 at% or more. In addition, more preferably, T is Fe (formed only of Fe).

[0023] In both the R-T-B-based magnet (A) and the R-T-B-based magnet (B), preferably, the amount of B contained is 4 at% or more and 8 at% or less. From the viewpoints of plastic deformation, the residual magnetic flux density Br, and the coercive force, it is preferable that the amount of B is within the above range.

[0024] In addition, preferably, the R-T-B-based magnet (A) and the R-T-B-based magnet (B) are formed of R, T, and B. Specifically, preferably, the R-T-B-based magnet (A) and the R-T-B-based magnet (B) are both formed of R, T, B, and inevitably contained elements. From the viewpoints of plastic deformation, the residual magnetic flux density Br, and the coercive force, it is preferable not to contain elements other than R, T, and B.

[0025] In addition, in the anisotropic magnet of the embodiment, preferably, when the total amount of the R-T-B-based magnet (A) and the R-T-B-based magnet (B) is set to 100 vol%, the amount of the R-T-B-based magnet (A) contained is 30 vol% or more and 50 vol% or less, and the amount of the R-T-B-based magnet (B) contained is 50 vol% or more and 70 vol% or less. It should be noted that the amounts of the R-T-B-based magnet (A) and the R-T-B-based magnet (B) can be confirmed by spot composition analysis of regions based on EPMA (electron probe microanalysis) and composition analysis based on surface or line analysis using SEM-EDX (scanning electron microscope-energy dispersive spectrometer). Here, the composition analysis of the anisotropic magnet of the embodiment can be performed by observing a cross-section perpendicular to the easy magnetization axis.

[0026] In addition, for the anisotropic magnet of the embodiment, in the case of observing a cross-section perpendicular to the easy magnetization axis, the size of the region containing the R-T-B-based magnet (A) and the size of the region containing the R-T-B-based magnet (B) are generally both 30 μm or more and 500 μm or less. It should be noted that the analysis of the regions can be confirmed by spot composition analysis of regions based on EPMA and composition analysis based on surface or line analysis using SEM-EDX.

[0027] The anisotropic magnet of the embodiment can be particularly applied to an optical actuator such as Optical Image Stabilization (OIS).

[0028] <Manufacturing Method of Anisotropic Magnet>

[0029] The manufacturing method of the anisotropic magnet of the embodiment includes a mixing step and a hot working step. According to the above manufacturing method, the above anisotropic magnet can be manufactured.

[0030] (Mixing Step)

[0031] The mixing step is a step of mixing an R-T-B-based magnet powder (A1) (R represents a rare earth element including Nd and / or Pr, and T represents Fe or Fe and Co.) having a rare earth element content of more than 12 at% and less than 19 at% and an R-T-B-based magnet powder (B1) (R represents a rare earth element including Nd and / or Pr, and T represents Fe or Fe and Co.) having a rare earth element content greater than that of the R-T-B-based magnet (A1) and a rare earth element content of 19 at% or less to obtain a mixed powder.

[0032] First, prepare R-T-B system magnet powders (A1) and R-T-B system magnet powders (B1). Both the R-T-B system magnet powders (A1) and the R-T-B system magnet powders (B1) contain R as a ternary tetragonal compound. 2 Fe 14 B phase (e.g., R 2 Fe 14 B type compound phase) as the main phase. In addition, the R-T-B system magnet powders (A1) and the R-T-B system magnet powders (B1) generally also contain rich R phases, etc. R represents a rare earth element including Nd and / or Pr. Preferably, R contains Nd as an essential component, and more preferably, R is Nd or Nd and Pr. As the rare earth element, it may also include at least one selected from scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu). T represents Fe or Fe and Co. When T is Fe and Co, preferably, when the total amount of Fe and Co is set to 100 at%, the amount of Fe contained is 50 at% or more. In addition, more preferably, T is Fe (formed only of Fe).

[0033] In addition, the amount of B preferably contained in both the R-T-B system magnet powders (A1) and the R-T-B system magnet powders (B1) is 4 at% or more and 8 at% or less.

[0034] In addition, the R-T-B system magnet powders (A1) and the R-T-B system magnet powders (B1) are preferably formed of R, T, and B. That is, preferably, the R-T-B system magnet powders (A1) and the R-T-B system magnet powders (B1) are both formed of R, T, B, and inevitably contained elements. From the viewpoints of plastic deformation, residual magnetic flux density Br, and coercive force, it is preferred not to contain elements other than R, T, and B.

[0035] The Nd-T-B system magnet powders (A1) and the R-T-B system magnet powders (B1) are manufactured, for example, by the melt spinning method (ultra-rapid quenching method). Specifically, the Nd-T-B alloy is subjected to high-frequency induction heating under negative pressure or in an argon atmosphere to dissolve it. Here, then, the molten solution of the dissolved alloy is sprayed onto a copper rotating roll to perform ultra-rapid quenching (high-speed cooling) to produce a strip-shaped thin strip. Then, the thin strip is pulverized. For example, preferably, after the thin strip is broken into several mm to several tens of mm, it is pulverized using a pulverizer or the like. The pulverized powder is obtained by pulverizing the thin strip.

[0036] After crushing a strip-shaped thin strip into crushed powder, it is heat-treated to obtain magnet powder. At this stage, the directions of the easy magnetization axes of the respective crystal grains of the magnet powder are not unified in one direction, so it is magnetically isotropic. It should be noted that both the Nd-T-B-based magnet powder (A1) and the R-T-B-based magnet powder (B1) can be manufactured using an Nd-T-B-based alloy adjusted so that the amount of rare earth elements falls within the above range.

[0037] It should be noted that it is possible to use pre-manufactured magnet powder instead of actually manufacturing magnet powder. For example, as magnet powder with increased density by hot pressing, Magnequench provides magnet powder that is isotropic magnetically by crushing an Nd-T-B-based thin strip produced by the ultra-rapid quenching method.

[0038] As described above, the R-T-B-based magnet powder (A1) and the R-T-B-based magnet powder (B1) are mixed. At this time, preferably, when the total amount of the R-T-B-based magnet powder (A1) and the R-T-B-based magnet powder (B1) is set to 100 vol%, the R-T-B-based magnet powder (A1) in an amount of 30 vol% or more and 50 vol% or less and the R-T-B-based magnet powder (B1) in an amount of 50 vol% or more and 70 vol% or less are mixed.

[0039] (Hot working process)

[0040] The hot working process is a process of hot working the mixed powder obtained through the above mixing process to obtain an anisotropic magnet. Hereinafter, the case of manufacturing an annular anisotropic magnet will be described as an example.

[0041] Specifically, hot pressing is performed on the above mixed powder to produce a sintered magnet body. First, a first mold is prepared. The first mold is composed of a hollow cylindrical die, a hollow cylindrical upper punch and a lower punch inserted into the inside of the die, and a cylindrical core arranged inside the upper punch and the lower punch. The die, the upper punch, the lower punch, and the core are formed of a conductive material (for example, graphite, cemented carbide, etc.).

[0042] Next, the mixed powder is filled into the first mold and placed in a sintering device (SPS device: spark plasma sintering device) for sintering, and the sintered magnet body (hot-pressed magnet body) is taken out from the first mold.

[0043] The mixed powder filled in the cavity of the first mold is pressurized by an upper punch and a lower punch by applying pressure between an upper electrode and a lower electrode. In addition, an electric current flows from the upper electrode to the upper punch, passes through the die, the core, and the mixed powder, and flows through the lower punch to the lower electrode, thereby generating Joule heat and generating a discharge plasma within the mixed powder, whereby the mixed powder is heated. For example, it is heated to 600 to 700 °C (hot pressing) while being pressurized at 30 to 50 MPa. In addition, sintering is preferably carried out under a negative pressure in an inert environment, specifically preferably in an argon environment or a nitrogen environment.

[0044] After heating, the current is cut off for cooling. After cooling to a specified temperature, the first mold is taken out of the sintering device. Specifically, a ring-shaped sintered magnet body formed by sintering the mixed powder is taken out of the first mold. For the ring-shaped sintered magnet body in this state, its relative density is about 90%, the easy magnetization axes of its grains are randomly oriented, and it is magnetically isotropic.

[0045] Next, a hot-worked magnet is made from the sintered magnet. First, a second mold is prepared. It should be noted that the preparation of the second mold can be carried out simultaneously with the preparation of the first mold or before the preparation of the first mold.

[0046] The above-mentioned sintered magnet is placed in the second mold, and the second mold is placed in the sintering device for thermoplastic processing.

[0047] In the sintering device, an upper electrode is arranged at the upper end of the punch, and a lower electrode is arranged at the lower end of the die. The upper electrode and the lower electrode are formed of a conductive material (for example, graphite, cemented carbide, etc.). The sintering device is equipped with a power supply device and a control device for applying a specified voltage between the upper electrode and the lower electrode to supply a specified current. The sintering device can either share the sintering device used for the above-mentioned hot pressing or use other devices.

[0048] The sintered magnet body disposed between the die and the punch of the second mold is pressed by the die and the punch. In addition, heating is performed by the discharge plasma and Joule heat generated when current flows through the path of upper electrode → punch → sintered magnet body → die → lower electrode. In thermoplastic processing, after applying a pressure of 30 to 100 MPa, heating is started. For example, while heating to 600 °C or higher and 700 °C or lower, pressure is applied. During heating, ON-OFF DC pulse energization is performed on the sintered magnet body. In thermoplastic processing, it is ideal to adjust the pressure so that the processing speed does not increase, and it is preferable to keep the processing speed constant. Preferably, thermoplastic processing is performed under negative pressure or in an inert environment. Specifically, it is performed in an argon environment or a nitrogen environment. Preferably, while monitoring the displacement, thermoplastic processing is performed during the period from the start of displacement to the completion of displacement. Here, regarding the monitoring of displacement, generally, the displacement amount of the servo motor for pressure control is monitored.

[0049] The grains of the hot-worked magnet obtained by thermoplastic processing have a flat shape, and the easy magnetization axis of the grains is perpendicular to the flat plane of the grains. The grains when producing a thin strip by the ultra-rapid cooling method are isotropic in shape, but through thermoplastic processing, the grains grow into a flat shape, and the flat planes of the particles are mechanically aligned in the pressing direction. That is to say, it means that the pressing direction (the short axis direction of the grains) coincides with the easy magnetization axis. Therefore, the easy magnetization axis of the grains in the magnet coincides with the thickness direction of the hot-worked magnet (the sintered magnet body changes into a hot-worked magnet through thermoplastic processing). It should be noted that the hot-worked magnet adopts a manufacturing method for producing an anisotropic magnet by so-called hot extrusion processing.

[0050] After heating, the current of the sintering device is cut off and it is cooled. After cooling to a specified temperature, the second mold is taken out from the sintering device, and the annular hot-worked magnet (anisotropic magnet) obtained by thermoplastic processing of the sintered magnet body is taken out from the second mold.

[0051] The anisotropic magnet obtained by thermoplastic processing is magnetically anisotropic. For example, it is annular, and its relative density is approximately the true density. The anisotropic magnet thus obtained suppresses the decrease in coercive force and improves magnetization. That is, it is considered that the above-mentioned anisotropic magnet has excellent magnetic properties and sufficient anisotropization.

[0052] It should be noted that generally, it is considered that the compositions of the R-T-B-based magnet powders (A1) and R-T-B-based magnet powders (B1) used in the manufacturing method of the anisotropic magnet of the embodiment are also maintained as they are in the obtained anisotropic magnet. Therefore, it is considered that the compositions of the R-T-B-based magnet powders (A1) and R-T-B-based magnet powders (B1) are the same as the compositions of the R-T-B-based magnet (A) and R-T-B-based magnet (B), respectively. In addition, generally, it is considered that the mixing ratios of the R-T-B-based magnet powders (A1) and R-T-B-based magnet powders (B1) used in the manufacturing method of the anisotropic magnet of the embodiment are also maintained as they are in the obtained anisotropic magnet. Therefore, it is considered that the mixing ratios of the R-T-B-based magnet powders (A1) and R-T-B-based magnet powders (B1) are the same as the ratios of the R-T-B-based magnet (A) and R-T-B-based magnet (B) in the anisotropic magnet, respectively.

[0053] [Examples]

[0054] [Example 1]

[0055] (Mixing step)

[0056] 50 vol% of Nd-Fe-B-based magnet powder (A1) (Nd 13 Fe Bal B 6 (Nd content: 13 at%, B content: 6 at%, the remaining part is Fe), MQP-A (trade name), manufactured by Magnequench Co., Ltd.) and 50 vol% of Nd-Fe-B-based magnet powder (B1) (Nd 14.5 Fe Bal B 6 (Nd content: 14.5 at%, B content: 6 at%, the remaining part is Fe), MQU (trade name) series, manufactured by Magnequench Co., Ltd.) were mixed to obtain a mixed powder.

[0057] (Hot working step)

[0058] As described above, the mixed powder was hot-pressed to produce a sintered magnet body. Then, through thermoplastic processing, a hot-worked magnet (anisotropic magnet including R-T-B-based magnet (A) and R-T-B-based magnet (B)) was produced.

[0059] [Example 2]

[0060] Except for using the mixed powder prepared as described below as the mixed powder, a hot-worked magnet (anisotropic magnet including R-T-B-based magnet (A) and R-T-B-based magnet (B)) was produced in the same manner as in Example 1.

[0061] Mix 30 vol% of Nd-Fe-B magnet powder (A1) (Nd 13 Fe Bal B 6 (Nd content: 13 at%, B content: 6 at%, the balance being Fe), MQP-A (trade name), manufactured by Magnequench) and 70 vol% of Nd-Fe-B magnet powder (B1) (Nd 14.5 Fe Bal B 6 (Nd content: 14.5 at%, B content: 6 at%, the balance being Fe), MQU (trade name) series, manufactured by Magnequench) to obtain a mixed powder.

[0062] [Comparative Example 1]

[0063] Except for using the Nd-Fe-B magnet powder (Nd 14.5 Fe Bal B 6 (Nd content: 14.5 at%, B content: 6 at%, the balance being Fe), MQU (trade name) series, manufactured by Magnequench) alone instead of the mixed powder, a hot-worked magnet (anisotropic magnet) was produced in the same manner as in Example 1.

[0064] [Comparative Example 2]

[0065] Except for using the Nd-Fe-B magnet powder (Nd 13 Fe Bal B 6 (Nd content: 13 at%, B content: 6 at%, the balance being Fe), MQP-A (trade name), manufactured by Magnequench) alone instead of the mixed powder, a hot-worked magnet (anisotropic magnet) was produced in the same manner as in Example 1.

[0066] [Comparative Example 3]

[0067] Except for using the mixed powder prepared as described below as the mixed powder, a hot-worked magnet (anisotropic magnet) was produced in the same manner as in Example 1.

[0068] Mix 30 vol% of Nd-Fe-B magnet powder (A1) (Nd 11.5 Fe Bal B 5.8 Nb 1.5(Nd content: 11.5 at%, B content: 5.8 at%, Nb content: 1.5 at%, the balance being Fe), MQP14-12 (trade name), manufactured by Magnequench) and 70 vol% of Nd-Fe-B-based magnet powder (B1) (Nd 14.5 Fe Bal B 6 (Nd content: 14.5 at%, B content: 6 at%, the balance being Fe), MQU (trade name) series, manufactured by Magnequench) were mixed to obtain a powder.

[0069] <Measurement of Magnetic Properties>

[0070] The static magnetic properties of the anisotropic magnets obtained by the investigation were examined. Specifically, after magnetizing the anisotropic magnets in the thickness direction (easy magnetization axis direction) by applying a magnetic field of 5 T, measurement was performed using a vibrating sample magnetometer (VSM). Figure 1 The results are shown therein. That is, Figure 1 is a graph showing the demagnetization curves of the magnets produced in the examples and comparative examples.

[0071] In Comparative Example 3, there was insufficient liquid phase for deformation, the workability was poor, and the anisotropization was insufficient. In addition, due to heating, the main phase was adversely affected, and the magnetization and coercive force were greatly reduced. On the other hand, in Examples 1 and 2, the magnetization could be increased while suppressing the decrease in coercive force.

[0072] It should be noted that in the examples and comparative examples, it was considered that the compositions of the R-T-B-based magnet (A) and the R-T-B-based magnet (B) were the same as the compositions of the R-T-B-based magnet powder (A1) and the R-T-B-based magnet powder (B1), respectively. In addition, it was considered that the ratios of the R-T-B-based magnet (A) and the R-T-B-based magnet (B) in the anisotropic magnet were the same as the mixing ratios of the R-T-B-based magnet powder (A1) and the R-T-B-based magnet powder (B1), respectively.

Claims

1. An anisotropic magnet, comprising: an R-T-B-based magnet (A) containing more than 12 at% and less than 19 at% of a rare earth element, where R represents a rare earth element including Nd and / or Pr, and T represents Fe or Fe and Co; and an R-T-B-based magnet (B) containing more of the rare earth element than the amount of the rare earth element in the R-T-B-based magnet (A) and containing 19 at% or less of the rare earth element, where R represents a rare earth element including Nd and / or Pr, and T represents Fe or Fe and Co.

2. The anisotropic magnet according to claim 1, wherein in the R-T-B-based magnet (A), the amount of the rare earth element contained is 13 at% or more and less than 19 at%, in the R-T-B-based magnet (B), the amount of the rare earth element contained is more than the amount of the rare earth element in the R-T-B-based magnet (A) and is 19 at% or less.

3. The anisotropic magnet according to claim 1 or 2, wherein the R-T-B-based magnet (A) is formed of R, T, and B, and the R-T-B-based magnet (B) is formed of R, T, and B.

4. A method for manufacturing an anisotropic magnet, comprising: a mixing step of mixing an R-T-B-based magnet powder (A1) containing more than 12 at% and less than 19 at% of a rare earth element and an R-T-B-based magnet powder (B1) containing more of the rare earth element than the amount of the rare earth element in the R-T-B-based magnet powder (A1) and containing 19 at% or less of the rare earth element to obtain a mixed powder, where R represents a rare earth element including Nd and / or Pr, and T represents Fe or Fe and Co; and a hot working step of hot working the mixed powder obtained by the mixing step to obtain an anisotropic magnet.

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