Hot-processed magnet

Abstract

To provide a hot-processed magnet with high coercive force.SOLUTION: A hot-processed magnet 2 contains a rare earth element R, a transition metal element T, and boron. The hot-processed magnet 2 contains Nd as the rare earth element R. The hot-processed magnet 2 contains Fe as the transition metal element T. The hot-processed magnet includes a plurality of main phase particles 4 and a grain boundary phase 6 located between the plurality of main phase particles 4. The plurality of main phase particles 4 contain a rare earth element R, a transition metal element T, and boron. The grain boundary phase 6 includes a plurality of crystal grains 8. The plurality of crystal grains 8 are in contact with one or more main phase particles 4. The zone axes cza of the plurality of crystal grains 8 are oriented along one direction D.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to hot worked magnets. [Background technology]

[0002] In recent years, with the spread of wind power generation and electric vehicles, the demand for neodymium magnets has increased, and improvements in their properties are being sought. In order to elucidate the mechanism by which coercivity, an important property of neodymium magnets, is expressed, a great deal of research and development has been carried out in recent years, and understanding of the mechanism by which coercivity is expressed has deepened (see, for example, Patent Document 1 and Non-Patent Document 1 below). The coercivity of neodymium magnets depends on the ferromagnetic materials that make up the neodymium magnet (for example, NdFe 14 B) is theoretically determined by the crystalline anisotropy field Ha. However, because actual neodymium magnets contain polycrystals, they only exhibit about 20% of the theoretical value of coercivity. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-009421 [Non-patent literature]

[0004] [Non-Patent Document 1] H. Sepehri-Amin et al., Grainboundary and interface chemistry of an Nd-Fe-B-based sintered magnet, ActaMaterialia 60 (2012) 819-830, Published by Elsevier Ltd. Summary of the Invention [Problem to be solved by the invention]

[0005] An object of one aspect of the present disclosure is to provide a hot-worked magnet having high coercivity. [Means for solving the problem]

[0006] For example, as described below, one aspect of the present disclosure relates to a hot-processed magnet according to any one of [1] to

[14] .

[0007] [1] A hot deformed magnet containing a rare earth element R, a transition metal element T, and boron (B), The hot-processed magnet contains Nd as the rare earth element R, The hot-processed magnet contains Fe as the transition metal element T, The hot-worked magnet includes a plurality of main phase grains and a grain boundary phase located between the plurality of main phase grains, the plurality of main phase particles include the rare earth element R, the transition metal element T, and the boron; the grain boundary phase includes a plurality of crystal grains, a plurality of the crystal grains are in contact with one or more of the main phase grains, The crystal zone axes of the plurality of crystal grains are oriented along one direction. Hot processed magnets.

[0008] [2] The plurality of crystal grains are non-magnetic. [1] A hot-deformed magnet according to the present invention.

[0009] [3] The area fraction of the cross section of the plurality of crystal grains in the cross section of the hot-deformed magnet is 3% or more and 8% or less; the cross section of the hot-processed magnet is parallel to the easy magnetization axis direction of the hot-processed magnet; The hot-processed magnet according to [1] or [2].

[0010] [4] The plurality of crystal grains contain the rare earth element R and the element M; the element M is at least one selected from the group consisting of Cu, Ga, Zn, Ni, and Cr, the content of the rare earth element R in the plurality of crystal grains is 50% by mass or more and 98% by mass or less, the content of the transition metal element T in the plurality of crystal grains is 0% by mass or more and 50% by mass or less, The content of the element M in the plurality of crystal grains is greater than 0 mass% and 35 mass% or less. The hot-processed magnet according to any one of [1] to [3].

[0011] [5] Each of the plurality of crystal grains is a cubic crystal, a tetragonal crystal, or an orthorhombic crystal; The zone axis is <100> , <010> , or <001> That is, The hot-processed magnet according to any one of [1] to [4].

[0012] [6] The plurality of crystal grains includes Nd and Cu; Each of the plurality of crystal grains is a cubic crystal, a tetragonal crystal, or an orthorhombic crystal; The space group indicating the symmetry of the crystal structure of the plurality of crystal grains is Pnma, I4 / mcm, Fm-3m, or Ia-3; The hot-processed magnet according to any one of [1] to [4].

[0013] [7] The width of the grain boundary phase containing one or more of the crystal grains is 4 nm or more and 500 nm or less in the direction of the easy axis of magnetization of the hot-worked magnet. The hot-processed magnet according to any one of [1] to [6].

[0014] [8] One or more of the main phase particles adjacent to one or more of the crystal grains include at least one of columnar crystals and equiaxed crystals, The hot-processed magnet according to any one of [1] to [7].

[0015] [9] The hot-processed magnet further contains an element M, the element M is at least one selected from the group consisting of Cu, Ga, Zn, Ni, and Cr, the content of the rare earth element R in the hot-deformed magnet is 26.00% by mass or more and 32.00% by mass or less, the boron content in the hot-processed magnet is 0.77% by mass or more and 1.15% by mass or less, The content of the element M in the hot-deformed magnet is 0.67% by mass or more and 7.30% by mass or less. The hot-processed magnet according to any one of [1] to [8].

[0016]

[10] The width of each of the plurality of main phase grains in the easy axis direction of magnetization of the hot-worked magnet is represented by S, The width of each of the plurality of main phase grains in a direction perpendicular to the easy axis direction is represented as L, said S being smaller than said L; L / S is between 2 and 10, The S is 20 nm or more and 200 nm or less. The hot-processed magnet according to any one of [1] to [9].

[11] A plurality of the crystal grains <100> and one or more of the main phase particles. <100> The angle between and is between 0° and 10°. [1]-

[10] . The hot-processed magnet according to any one of [1]-

[10] .

[12] A plurality of the crystal grains <010> and one or more of the main phase particles. <010> The angle between and is between 0° and 10°. [1]-

[10] . The hot-processed magnet according to any one of [1]-

[10] .

[13] A plurality of the crystal grains <001> and one or more of the main phase particles. <001> The angle between and is between 0° and 10°. [1]-

[10] . The hot-processed magnet according to any one of [1]-

[10] .

[14] The one direction in which the zone axes of the plurality of crystal grains are oriented is parallel to the zone axes of one or more of the main phase particles that are in contact with the plurality of crystal grains. [1] -

[13] The hot-processed magnet according to any one of [1] to

[13] . [Effects of the Invention]

[0017] According to one aspect of the present disclosure, a hot-worked magnet having high coercivity is provided. [Brief explanation of the drawings]

[0018] [Figure 1] (a) in Figure 1 is a schematic perspective view of a hot-processed magnet, and (b) in Figure 1 is a schematic view of a cross section of the hot-processed magnet in (a) in Figure 1 (a view along the arrow in the direction of line II in the hot-processed magnet), and the cross section shown in (b) in Figure 1 is parallel to the easy axis of magnetization of the hot-processed magnet. [Figure 2] FIG. 2 is an enlarged view of a part (region II) of the cross section shown in (b) of FIG. [Figure 3] (a) in Figure 3 is a schematic diagram of a cross section of one secondary particle containing polycrystals among multiple main phase particles contained in the hot-processed magnet, and (b) in Figure 3 is an enlarged view of a portion (region III) of the cross section shown in (a) in Figure 3. [Figure 4] FIG. 4 is a schematic diagram showing the unit cell and zone axes of each of an arbitrary pair of crystal grains included in the hot-deformed magnet. [Figure 5] FIG. 5 is a schematic perspective view of a specific example of a mold used in the method for producing a hot-worked magnet (hot plastic working step). [Figure 6] FIG. 6 is a backscattered electron image of a cross section of the hot-processed magnet of Example 1, and the cross section shown in FIG. 6 is parallel to the easy axis of magnetization of the hot-processed magnet. [Figure 7](a) in Figure 7 is a backscattered electron image of a cross section of the hot-processed magnet of Example 1, where the cross section shown in (a) in Figure 7 is parallel to the easy axis of magnetization of the hot-processed magnet, and (b) in Figure 7 is a backscattered electron image of a cross section of the hot-processed magnet of Example 1, where the cross section shown in (b) in Figure 7 is parallel to the easy axis of magnetization of the hot-processed magnet, and the cross sections shown in (a) in Figure 7 and (b) in Figure 7 are backscattered electron images taken at a higher magnification than the backscattered electron image shown in Figure 6. [Figure 8] FIG. 8 is a TEM (Transmission Electron Microscope) image of a cross section of the hot-processed magnet of Example 1, and the cross section shown in FIG. 8 is parallel to the easy axis of magnetization of the hot-processed magnet. [Figure 9] (a) in Figure 9 is an electron beam diffraction pattern measured by irradiating an electron beam at measurement point 1 (crystal grain) in the cross section shown in Figure 8, (b) in Figure 9 is an electron beam diffraction pattern measured by irradiating an electron beam at measurement point 2 (crystal grain) in the cross section shown in Figure 8, (c) in Figure 9 is an electron beam diffraction pattern measured by irradiating an electron beam at measurement point 3 (crystal grain) in the cross section shown in Figure 8, and (d) in Figure 9 is an electron beam diffraction pattern measured by irradiating an electron beam at measurement point 7 (crystal grain) in the cross section shown in Figure 8. [Figure 10] (a) in FIG. 10 is an electron beam diffraction pattern measured by irradiating an electron beam at measurement point 4 (NdO) in the cross section shown in FIG. 8, (b) in FIG. 10 is an electron beam diffraction pattern measured by irradiating an electron beam at measurement point 5 (main phase particle) in the cross section shown in FIG. 8, and (c) in FIG. 10 is an electron beam diffraction pattern measured by irradiating an electron beam at measurement point 6 (main phase particle) in the cross section shown in FIG. 8. [Figure 11] FIG. 11 is a schematic diagram showing the cross sections of multiple crystal grains and multiple main phase particles contained in the hot-processed magnet, and each cross section shown in FIG. 11 is parallel to the easy axis of magnetization of the hot-processed magnet. DETAILED DESCRIPTION OF THE INVENTION

[0019] Preferred embodiments of the present disclosure will be described below with reference to the drawings. In the drawings, equivalent components are designated by equivalent reference numerals. The present disclosure is not limited to the following embodiments. One arrow C and two arrows AB shown in FIG. 1 indicate three coordinate axes that are orthogonal to each other. Arrow C corresponds to the magnetization easy axis direction C of the hot-worked magnet. Each of the two arrows AB corresponds to the AB direction that is orthogonal to the magnetization easy axis direction C. The magnetization easy axis direction C and the AB direction are common to all figures.

[0020] (hot-processed magnets) The hot-processed magnet according to this embodiment contains at least a rare earth element R, a transition metal element T, and boron (B).

[0021] The hot-processed magnet contains at least neodymium (Nd) as the rare earth element R. The hot-processed magnet may further contain other rare earth elements R in addition to Nd. The other rare earth elements R contained in the hot-processed magnet may be at least one element selected from the group consisting of scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu). The hot-processed magnet does not necessarily contain heavy rare earth elements (e.g., both Dy and Tb).

[0022] The hot-processed magnet contains at least iron (Fe) as the transition metal element T. The hot-processed magnet may contain only Fe as the transition metal element T. The hot-processed magnet may contain both Fe and cobalt (Co) as the transition metal element T.

[0023] (a) in FIG. 1 is a perspective view of the hot-processed magnet 2. (b) in FIG. 1 is a schematic diagram of a cross section 2cs of the hot-processed magnet 2. The cross section 2cs of the hot-processed magnet 2 is approximately or completely parallel to the easy axis direction C of the hot-processed magnet 2. The easy axis direction C is a direction parallel to a line connecting a pair of magnetic poles of the hot-processed magnet 2. In other words, the easy axis direction C is a direction from the south pole of the hot-processed magnet 2 to the north pole of the hot-processed magnet 2. The easy axis direction C may be determined based on a measurement of the magnetic flux distribution of the hot-processed magnet 2. The easy axis direction C may also be determined based on a measurement of the magnetic flux distribution of an analysis sample separated from the hot-processed magnet 2. As described above, the AB direction is perpendicular to the easy axis direction C.

[0024] The hot-worked magnet 2 shown in (a) of FIG. 1 is a rectangular parallelepiped (plate). However, the shape of the hot-worked magnet 2 is not limited to a rectangular parallelepiped. For example, the shape of the hot-worked magnet 2 may be a cube, a polygonal prism, an arc segment, an annular sector, a sphere, a disk, a cylinder, a tube, or a ring. For example, the shape of the cross section 2cs of the hot-worked magnet 2 may be a polygon, an arc (circular chord), a bow, an arch, a C-shape, or a circle.

[0025] FIG. 2 is an enlarged view of a portion (region II) of the cross section 2cs shown in (b) of FIG. 1. As shown in FIG. 2, the hot-processed magnet 2 includes a plurality of main phase particles 4 and a grain boundary phase 6 located between the plurality of main phase particles 4. In this disclosure, the grain boundary phase 6 is a general term for all components other than the plurality of main phase particles 4 (i.e., the remaining components of the hot-processed magnet 2 excluding all of the main phase particles 4). The hot-processed magnet 2 may include multiple grain boundary phases 6 at different positions. For example, the grain boundary phase 6 may be present at a grain boundary surrounded by three or more main phase particles 4 (grain boundary multiplex). For example, the grain boundary phase 6 may be present at a grain boundary between two main phase particles 4 (two-grain grain boundary).

[0026] The multiple main phase particles 4 contain at least a rare earth element R, a transition metal element T, and B. The main phase particle 4 contains at least Nd as the rare earth element R. The main phase particle 4 contains at least Fe as the transition metal element T. One main phase particle 4 may be one crystal grain (i.e., primary particle). At least some or all of the multiple main phase particles 4 contained in the hot-processed magnet 2 may be secondary particles containing polycrystals (multiple primary particles). The hot-processed magnet 2 may contain multiple secondary particles. One secondary particle may contain multiple main phase particles 4. The main phase particle 4 is R2T 14 Includes crystals (single crystal or polycrystal) of B. R2T 14 B is a ternary intermetallic compound with hard magnetism, i.e., R2T 14 The main phase grains 4 containing B crystals are hard magnetic materials. 14 It may consist of only crystals of B. 14 The crystal of B may be tetragonal. 14 The crystal axes of B are represented as the a-axis, b-axis, and c-axis. The a-axis, b-axis, and c-axis may be perpendicular to each other. R2T 14 The lattice constant of B in the a-axis direction is R2T 14 B may be equal to the lattice constant in the b-axis direction, and R2T 14 The lattice constant of B in the c-axis direction may be different from the lattice constants in the a-axis direction and the b-axis direction. 14 The c-axis of B may be approximately or completely parallel to the magnetization easy axis direction C of the hot-processed magnet 2. In other words, R2T 14 The (001) plane of the tetragonal crystal of B may be approximately or completely perpendicular to the direction of the easy axis C of magnetization of the hot-processed magnet 2 .

[0027] For example, R2T constituting the main phase particles 4 14 B is (Nd 1-x Pr x )2(Fe 1-y Co y ) 14B. x may be 0 or more and less than 1. y may be 0 or more and less than 1. The main phase particles 4 may contain heavy rare earth elements such as Tb and Dy as the rare earth element R in addition to light rare earth elements. The main phase particles 4 may contain other elements in addition to R, T, and B. For example, R2T 14 A portion of B in B may be substituted with another element such as carbon (C). The composition within the main phase particle 4 may be uniform. The composition within the main phase particle 4 may be non-uniform. For example, the concentration distribution of each of R, T, and B in the main phase particle 4 may have a gradient.

[0028] As shown in FIG. 2, the grain boundary phase 6 includes a plurality of crystal grains 8. The plurality of crystal grains 8 may be non-magnetic rather than paramagnetic. Each of the plurality of crystal grains 8 may be single crystal or polycrystalline. As shown in FIGS. 2 and 4, at least some or all of the plurality of crystal grains 8 are in contact with one or more main phase particles 4.

[0029] The unit cell uc8a shown in FIG. 4 represents the unit cell of any one crystal grain 8a that is in contact with one or more main phase particles 4. Another unit cell uc8b shown in FIG. 4 represents the unit cell of another crystal grain 8b (any one crystal grain 8 different from the above crystal grain 8a) that is in contact with one or more main phase particles 4. The three basic translation vectors that constitute the unit cell uc8a and the unit cell uc8b are represented as vector a, vector b, and vector c. For example, each of the multiple crystal grains 8 (crystal grains 8a and 8b) may be a cubic crystal, a tetragonal crystal, or an orthorhombic crystal. When vector a, vector b, and vector c are perpendicular to each other and the lengths of vector a, vector b, and vector c are equal to each other, each of the crystal grain 8a (unit cell uc8a) and the crystal grain 8b (unit cell uc8b) is a cubic crystal. When vector a, vector b, and vector c are perpendicular to each other, and the lengths of vector a and vector b are equal, and the length of vector c is different from the lengths of vector a and vector b, each of crystal grain 8a (unit cell uc8a) and crystal grain 8b (unit cell uc8b) is a tetragonal crystal. When vector a, vector b, and vector c are perpendicular to each other, and the lengths of vector a and vector b are different from each other, each of crystal grain 8a (unit cell uc8a) and crystal grain 8b (unit cell uc8b) is an orthorhombic crystal. In the present disclosure, orthorhombic crystal may imply rhombic crystal.

[0030] As shown in FIG. 4 , the zone axes cza of multiple crystal grains 8 (e.g., crystal grains 8a and 8b) that contact one or more main phase particles 4 are oriented along a single direction (orientation direction D). The zone axes cza of each of multiple crystal grains 8 that contact the same main phase particle 4 may be oriented along the same direction (orientation direction D). For example, the angle between the zone axes cza of any two of the multiple crystal grains 8 may be 5° or less, or 3° or less. In other words, the angle between the zone axis cza of any one crystal grain 8 and the orientation direction D may be 2.5° or less, or 1.5° or less. The zone axes cza of multiple crystal grains 8 may be approximately or completely parallel to each other. In other words, the directions of the zone axes cza of multiple crystal grains 8 may be the same and may coincide with the orientation direction D. Multiple crystal grains 8 whose zone axes cza are oriented along a single direction (orientation direction D) may be locally contained in only a portion of the hot-worked magnet 2. A plurality of crystal grains 8 whose zone axes cza are oriented along one direction (orientation direction D) may be present throughout the hot-worked magnet 2.

[0031] [Zone axis definition] Any two non-parallel lattice planes (e.g., (hkl) plane and (h'k'l') plane) in any crystal (e.g., crystal grain 8 or main phase particle 4) always intersect. h, k, l, h', k', and l' are Miller indices. The intersection line between the (hkl) plane and the (h'k'l') plane is <uvw>When facing the direction, the intersection of the (hkl) plane and the (h'k'l') plane is <uvw>The zone axes ( u is equal to kl'-lk', v is equal to lh'-hl', and w is equal to hk'-kh'. The (hkl) plane and (h'k'l') plane belong to the zone represented as [uvw]. <uvw>) is always perpendicular to the normal of the lattice planes (i.e., (hkl) planes and (h'k'l') planes) belonging to the crystal zone ([uvw]), so the (hkl) planes and (h'k'l') planes and the crystal zone axis ( <uvw>) satisfies hu+kv+lw=0 and h'u+k'v+l'w=0. These equations are called Weiss's zone law. [Orientation of the zone axis of the crystal grains] For example, the zone axis cza of each of the plurality of crystal grains 8 is <100> , <010> , or <001> It may be. For example, the number of crystal grains 8 adjacent to one or more main phase particles 4 <100> The crystal grains 8 may be oriented along one direction (orientation direction D). <100> The angle between any one grain 8 may be 5° or less, or 3° or less. <100> and the orientation direction D may be 2.5° or less, or 1.5° or less. For example, the number of crystal grains 8 adjacent to one or more main phase particles 4 <010> The crystal grains 8 may be oriented along one direction (orientation direction D). <010> The angle between any one grain 8 may be 5° or less, or 3° or less. <010> and the orientation direction D may be 2.5° or less, or 1.5° or less. For example, the number of crystal grains 8 adjacent to one or more main phase particles 4 <001> The crystal grains 8 may be oriented along one direction (orientation direction D). <001> The angle between any one grain 8 may be 5° or less, or 3° or less. <001> and the orientation direction D may be 2.5° or less, or 1.5° or less. [Zone axes of crystal grains and main phase particles] For example, the zone axis cza′ of each of the one or more main phase particles 4 in contact with the plurality of crystal grains 8 is <100> , <010> , or <001> Each of the plurality of main phase particles 4 in the hot-worked magnet 2 may be <001> may be approximately or completely parallel to the magnetization easy axis direction C of the hot-processed magnet 2. As shown in FIG. 11, the angle between the zone axis cza of each of the plurality of crystal grains 8 and the zone axis cza′ of each of the one or more main phase particles 4 in contact with the plurality of crystal grains 8 may be represented as angle θ. For example, the angle θ is <100> and one or more main phase particles 4, <100> and may be an angle between. For example, the angle θ is <010> and one or more main phase particles 4, <010> The angle may be between and. For example, the angle θ is <001> and one or more main phase particles 4, <001> The angle may be between and. For example, the angle θ may be 0° to 19.5°, 0° to 10°, 0° to 9.2°, 1.5° to 19.5°, 1.5° to 10°, or 1.5° to 9.2°. As the angle θ decreases, the crystal structure of each crystal grain 8 in the grain boundary phase 6 and the crystal structure of each main phase grain 4 tend to match at the interface between them. As a result, the energy barrier at the interface between the grain boundary phase 6 and the main phase grain 4 increases, and domain wall movement through the grain boundary phase 6 is likely to be suppressed. Therefore, when the angle θ is 10° or less, the coercivity and squareness ratio of the hot-worked magnet 2 tend to increase. For the same reason, the average value of the angle θ may be 0° or more and 19.5° or less, 0° or more and 10° or less, 0° or more and 9.2° or less, 1.5° or more and 19.5° or less, 1.5° or more and 10° or less, or 1.5° or more and 9.2° or less. For example, the average value of the angle θ may be the average value of the angles θ of 10 or more pairs of crystal grains 8 and main phase grains 4. 11 , the angle between one direction (orientation direction D) in which the zone axes cza of the plurality of crystal grains 8 are aligned and each zone axis cza′ of one or more main phase particles 4 in contact with the plurality of crystal grains 8 may be equal to the angle θ, and may be 0° to 19.5°, 0° to 10°, 0° to 9.2°, 1.5° to 19.5°, 1.5° to 10°, or 1.5° to 9.2°. For example, the one direction (orientation direction D) in which the zone axes cza of the plurality of crystal grains 8 are aligned may be approximately or completely parallel to the zone axis cza′ of each main phase particle 4 in contact with the plurality of crystal grains 8. Of the multiple zone axes of each of the multiple crystal grains 8 in contact with one or more main phase particles 4, the zone axis oriented along one direction (orientation direction D) may be represented as cza1. Of the multiple zone axes of each of the multiple crystal grains 8 in contact with one or more main phase particles 4, the zone axis that forms an angle of 0° or more and 10° or less with the zone axis cza′ of each of the multiple main phase particles 4 in contact with the multiple crystal grains 8 may be represented as cza2. cza1 and cza2 may be identical or different from each other. That is, the zone axis cza1 of a crystal grain 8 oriented along one direction (orientation direction D) may be identical to or different from the zone axis cza2 of a crystal grain 8 that forms an angle of 0° or more and 10° or less with the zone axis cza′ of the main phase particle 4.

[0032] [Measurement of the direction of the zone axis] The direction of the zone axis cza of each of the plurality of crystal grains 8 is identified based on the electron diffraction pattern of each of the plurality of crystal grains 8. The electron diffraction pattern may be measured by selected area electron diffraction (SAED) using a transmission electron microscope (TEM) or nano beam electron diffraction (NBED) using a TEM. An electron beam diffraction pattern of any one crystal grain 8 can be obtained by irradiating an electron beam onto the cross section of any one crystal grain 8 exposed in the cross section 2cs of the hot-worked magnet 2. As described above, the cross section 2cs of the hot-worked magnet 2 is approximately or completely parallel to the easy axis direction C of magnetization. The electron beam diffraction pattern includes multiple diffraction spots derived from multiple lattice planes in one crystal grain 8. The spot located in the center of the electron beam diffraction pattern (the central spot represented as (000)) is a spot of the electron beam that has passed through the crystal grain 8 without being diffracted by each lattice plane in the crystal grain 8. For example, <uvw>The direction of the zone axis cza expressed as follows may be the direction of a straight line passing through the center of the diffraction spot and the center of the central spot originating from the lattice plane expressed as the (uvw) plane. <uvw>The direction of the zone axis cza expressed as follows may be the direction of a straight line passing through the spot originating from a lattice plane parallel to the (uvw) plane and the center of the central spot. The above method identifies the direction of the zone axis cza of each of the multiple crystal grains 8. By comparing the electron diffraction patterns of each of the multiple crystal grains 8 with each other, it can be confirmed whether the zone axes cza of the multiple crystal grains 8 are oriented along one direction (orientation direction D). For example, if the electron diffraction patterns of each of the multiple crystal grains 8 approximately or completely match in the positions of the diffraction spots derived from each lattice plane and in the direction in which the multiple diffraction spots are arranged, the zone axes cza of the multiple crystal grains 8 are approximately or completely parallel to each other. Using a method similar to the above, the direction of the zone axis cza' of each of the one or more main phase particles 4 in contact with the plurality of crystal grains 8 is also identified. That is, the direction of the zone axis cza' of each of the one or more main phase particles 4 in contact with the plurality of crystal grains 8 is identified based on the electron diffraction pattern of each main phase particle 4. An electron beam is incident on the cross section of any one of the main phase particles 4 exposed in the cross section 2cs of the hot-worked magnet 2, thereby obtaining the electron diffraction pattern of any one of the main phase particles 4. The crystal structure of each main phase particle 4 may also be identified based on the electron diffraction pattern of each main phase particle 4. [Measuring method for angle θ] The angle θ mentioned above may be measured by the following method using a TEM. A sample (thin piece) is prepared from the hot-worked magnet 2 by a processing method such as milling using a focused ion beam (FIB). The thickness of the sample is adjusted to a thickness suitable for analysis using a TEM (usually 100 nm or less). Since the thickness of the grain boundary phase 6 in the sample is on the order of a few nanometers, the TEM is set in nanobeam diffraction mode. By the above-described method, the crystal structure of each crystal grain 8 in the sample and the crystal structure of each main phase grain 4 in contact with each crystal grain 8 in the sample are specified in advance. The direction of the electron beam incident on the crystal grains 8 in the sample is <uvw>The tilt angle of the stage on which the sample is placed in the TEM is adjusted so that the electron beam is parallel to the normal of the (uvw) plane. <uvw>The electron diffraction pattern of the crystal grains 8 is measured in a state where the electron beam is parallel to the crystal grains 8 in the sample. <001> (i.e., the normal to the (001) plane) is measured. From this electron diffraction pattern, the <uvw>(for example, <001> ) direction is identified. The direction of the electron beam incident on the main phase grain 4 in contact with the crystal grain 8 in the sample is <uvw>The tilt angle of the stage on which the sample is placed in the TEM is adjusted so that the electron beam is parallel to the main phase grains 4 (i.e., the normal to the (uvw) plane). <uvw>The electron diffraction pattern of the main phase grains 4 is measured in a state where the electron beam is parallel to the crystal zone axis. <001> The electron diffraction pattern of the main phase grains 4 is measured in a state parallel to the sample. <uvw>direction (e.g., <001> ) is identified. The electron diffraction patterns of the crystal grains 8 and the main phase particles 4 may be photographed with a digital camera or a CCD camera and analyzed as high-resolution image data. The crystal grains 8 and the main phase particles 4 in the sample <uvw>The angle θ is determined based on the direction of the crystal zone axis. <uvw>From the position of the diffraction spot corresponding to <uvw>A unit vector e1 may be specified that is parallel to the <uvw>From the position of the diffraction spot corresponding to <uvw>A unit vector e2 parallel to θ may be identified: θ = (180° / π) × arccos<e1,e2> The angle θ may be calculated from the following formula:<e1,e2> is the dot product of e1 and e2. For example, the crystal grains 8 and the main phase particles 4 <uvw>may be visualized based on image data of the electron diffraction patterns of the crystal grains 8 and the main phase particles 4, and the angle between the two vectors may be measured with a protractor.

[0033] The hot processed magnet 2 according to the present disclosure can have a high coercive force due to the following mechanism.

[0034] In a hot-processed magnet 2 in which the zone axes cza of multiple crystal grains 8 adjacent to one or more main phase grains 4 are aligned along a single orientation direction D, the pinning force of the domain walls in the grain boundary phase 6 containing the multiple crystal grains 8 is increased compared to a hot-processed magnet in which the zone axes cza of the multiple crystal grains 8 are not aligned. As a result, magnetization reversal due to domain wall movement is suppressed, each of the multiple main phase grains 4 is more likely to become a single magnetic domain, and the coercivity (HcJ) of the hot-processed magnet 2 is increased. Furthermore, the alignment of the zone axes cza of the multiple crystal grains 8 facilitates magnetic decoupling between the multiple main phase grains 4. This magnetic decoupling tends to increase the squareness ratio (Hk / HcJ) of the hot-processed magnet 2 while maintaining a high coercivity. Hk is the strength of the demagnetizing field corresponding to 90% of the remanence in the second quadrant of the magnetization curve of the hot-processed magnet 2. In contrast, when the grain boundary phase 6 is ferromagnetic or when the directions of the zone axes cza of the multiple crystal grains 8 in the grain boundary phase 6 are random, a multi-domain state in which domain walls penetrate the main phase grains 4 is likely to occur, magnetization reversal due to domain wall movement is likely to occur, and the coercive force is reduced. Previous research on hot-deformed magnets has focused on the macroscopic structure including the main phase grains and the grain boundary phase (e.g., the morphology of the main phase grains and the grain boundary phase). However, previous research has not addressed the microscopic structure of the grain boundary phase 6 (e.g., the structure and crystal orientation of the crystals in the grain boundary phase). The influence of the orientation of the zone axes cza of the multiple crystal grains 8 in the grain boundary phase 6 on the coercivity and squareness ratio was first discovered by the inventors of the present disclosure.

[0035] The technical scope of the hot-processed magnet 2 according to the present disclosure is not limited by the above mechanism.

[0036] For example, the coercive force (HcJ) of the hot-processed magnet 2 at 23°C may be 1313 kA / m or more and 1591 kA / m or less. For example, the remanence (Br) of the hot-worked magnet 2 at room temperature may be 1.25 T or more and 1.47 T or less, or 1.25 T or more and 1.46 T or less. For example, the squareness ratio (Hk / HcJ) of the hot-processed magnet 2 may be 90.5% or more and 98.5% or less, or 90.5% or more and 98.2% or less.

[0037] The angle between the one direction (orientation direction D) in which the zone axes cza of the plurality of crystal grains 8 in contact with one or more main phase particles 4 are oriented and the magnetization easy axis direction C is not particularly limited. The crystal structures of the plurality of crystal grains 8 in contact with one or more main phase particles 4 may be the same because this tends to increase the coercivity and squareness ratio. For the same reason, the compositions of the plurality of crystal grains 8 in contact with one or more main phase particles 4 may be the same. However, the crystal structures of the plurality of crystal grains 8 in contact with one or more main phase particles 4 may be different from each other. In other words, the zone axes cza of the plurality of crystal grains 8 having different crystal structures may be oriented along a single direction (orientation direction D). The compositions of the plurality of crystal grains 8 in contact with one or more main phase particles 4 may be different from each other. In other words, the zone axes cza of the plurality of crystal grains 8 having different compositions may be oriented along a single direction (orientation direction D).

[0038] The composition of the plurality of crystal grains 8 is different from the composition of the plurality of main phase particles 4. For example, the plurality of crystal grains 8 may contain at least one rare earth element R and at least one element M. The plurality of crystal grains 8 may contain at least Nd as the rare earth element R. The element M contained in the plurality of crystal grains 8 may be at least one selected from the group consisting of copper (Cu), gallium (Ga), zinc (Zn), nickel (Ni), and chromium (Cr). The element M contained in one crystal grain 8 may be an element different from the element M contained in another crystal grain 8. The plurality of crystal grains 8 may consist only of the rare earth element R and the element M. For example, the plurality of crystal grains 8 may further contain other elements in addition to the rare earth element R and the element M. For example, the plurality of crystal grains 8 may further contain at least one of Fe and Co as the transition metal element T. The plurality of crystal grains 8 may consist only of the rare earth element R, the element M, and the transition metal element T. The plurality of crystal grains 8 may be an intermetallic compound containing a rare earth element R and an element M. For example, as shown in FIG. 4, the unit cells of the plurality of crystal grains 8 (unit cell uc8a and unit cell uc8b) may contain the rare earth element R and the element M. For example, some of the rare earth elements R in the unit cells of the plurality of crystal grains 8 may be substituted with a transition metal element T or other elements. For example, some of the elements M in the unit cells of the plurality of crystal grains 8 may be substituted with a transition metal element T or other elements. The content (unit: mass %) of the rare earth element R in the plurality of crystal grains 8 may be greater than the content of the rare earth element R in the plurality of main phase particles 4. The concentration (unit: atomic %) of the rare earth element R in the plurality of crystal grains 8 may be greater than the concentration of the rare earth element R in the plurality of main phase particles 4. In other words, the rare earth element R may be concentrated in the plurality of crystal grains 8. Due to the concentration of the rare earth element R in the plurality of crystal grains 8, the plurality of crystal grains 8 are likely to become nonmagnetic phases. As a result, magnetic decoupling between the main phase particles 4 due to the plurality of crystal grains 8 is likely to occur, and the coercivity and squareness ratio are likely to increase. The surface of each main phase particle 4 (R2T 14 On the (001) plane of B, Nd ions are easily exposed, so the direction of the easy axis C of magnetization tends to be locally oriented in the in-plane direction of the surface of each main phase particle 4. In other words, the direction of the easy axis C tends to be locally parallel to the surface of each main phase particle 4. As a result, the surface of each main phase particle 4 tends to serve as a nucleus for magnetization reversal, and the coercivity tends to decrease. However, at the interface between the main phase particle 4 and the crystal grain 8, some of the Fe located on the surface of the main phase particle 4 is substituted with the element M. As a result, the direction of the crystalline electric field (anisotropy magnetic field) acting on the 4f electrons of the Nd ions exposed on the surface of the main phase particle 4 tends to change from the in-plane direction of the surface of each main phase particle 4 to the normal direction to the surface of each main phase particle 4. In other words, due to the element M derived from the multiple crystal grains 8, the direction of the easy axis C of magnetization on the surface of each main phase particle 4 tends to have the same uniaxial anisotropy as that inside (bulk) of each main phase particle 4. As a result, magnetization reversal caused by the surface of each main phase grain 4 is easily suppressed, and the coercive force is easily increased.

[0039] The content of the rare earth element R in the plurality of crystal grains 8 may be 50% by mass or more and 98% by mass or less, 60% by mass or more and 80% by mass or less, or 53.40% by mass or more and 96.27% by mass or less. The content of the transition metal element T in the plurality of crystal grains 8 may be 0% by mass or more and 50% by mass or less, 0% by mass or more and 20% by mass or less, 0% by mass or more and 10% by mass or less, or 3.20% by mass or more and 40.93% by mass or less. The content of the element M in the plurality of crystal grains 8 may be more than 0% by mass and 35% by mass or less, 2% by mass or more and 30% by mass or less, 20% by mass or more and 30% by mass or less, or 0.53% by mass or more and 31.54% by mass or less. The plurality of crystal grains 8 having the above composition are likely to be nonmagnetic. The nonmagnetic plurality of crystal grains 8 may be defined as a plurality of crystal grains 8 represented by the following chemical formula 1 or the following chemical formula 2. R α T β M γ (1) In the above chemical formula 1, α is 50% by mass or more and 98% by mass or less, 60% by mass or more and 80% by mass or less, or 53.40% by mass or more and 96.27% by mass or less; β in the above chemical formula 1 is 0% by mass or more and 50% by mass or less, 0% by mass or more and 20% by mass or less, 0% by mass or more and 10% by mass or less, or 3.20% by mass or more and 40.93% by mass or less; and γ in the above chemical formula 1 is more than 0% by mass and 35% by mass or less, 2% by mass or more and 30% by mass or less, 20% by mass or more and 30% by mass or less, or 0.53% by mass or more and 31.54% by mass or less. R A T B M C (2) A in the above chemical formula 2 is 40 atomic % or more and 94 atomic % or less, or 31.2 atomic % or more and 76.6 atomic % or less, B in the above chemical formula 2 is 0 atomic % or more and 30 atomic % or less, or 6.4 atomic % or more and 61.7 atomic % or less, and C in the above chemical formula 2 is 0.9 atomic % or more and 50 atomic % or less, or 0.9 atomic % or more and 48.3 atomic % or less. R in Chemical Formula 1 and Chemical Formula 2 is the rare earth element R described above, T in Chemical Formula 1 and Chemical Formula 2 is the transition metal element T described above, and M in Chemical Formula 1 and Chemical Formula 2 is the element M described above.

[0040] At least some or all of the plurality of crystal grains 8 in contact with one or more main phase particles 4 may contain Nd and Cu because the coercivity and squareness ratio are likely to increase. For example, as shown in FIG. 4 , the unit cells (unit cells uc8a and uc8b) of the plurality of crystal grains 8 may contain Nd as the rare earth element R and Cu as the element M. The plurality of crystal grains 8 containing Nd and Cu may further contain a transition metal element T. Because the coercivity and squareness ratio are likely to increase, each of the plurality of crystal grains 8 containing Nd and Cu may be a cubic, tetragonal, or orthorhombic crystal. Because the coercivity and squareness ratio are likely to increase, the space group indicating the symmetry of the crystal structure of the plurality of crystal grains 8 containing Nd and Cu may be Pnma, I4 / mcm, Fm-3m, or Ia-3. The notation of the space group is based on the Hermann-Mauguin notation. As shown in FIG. 4, the coercive force and squareness ratio tend to increase, so that the number of crystal grains 8 containing Nd and Cu is <100> However, the (010) planes of the crystal grains 8 containing Nd and Cu may be oriented along one direction (orientation direction D). Because this tends to increase the coercive force and squareness ratio, the (010) planes of the crystal grains 8 containing Nd and Cu may be substantially or completely parallel to each other, as shown in FIG. The crystal structure of each crystal grain 8 and the space group indicating the symmetry of the crystal structure may be identified based on the electron diffraction pattern of each crystal grain 8. By referencing a known database of crystal structures (e.g., the Inorganic Crystal Structure Database; ICSD), the Miller indices h, k, l (i.e., (hkl) planes) corresponding to each of the multiple spots (bright spots) in the electron diffraction pattern are identified. The multiple spots in the electron diffraction pattern are not uniform, have different brightnesses, and disappear at specific positions. By checking whether the electron diffraction pattern conforms to known systematic extinction rules and symmetry elements, the space group candidates are narrowed down. The electron diffraction pattern corresponding to the space group estimated by the above method is reproduced using simulation software (e.g., JEMS Electron Microscopy Software). The actual space group is identified by matching the reproduced electron diffraction pattern with the actually measured electron diffraction pattern. In other words, the actual space group is identified by repeating the above analysis until the electron diffraction pattern reproduced by the simulation software matches the actually measured electron diffraction pattern. As described above, the plurality of crystal grains 8 is not limited to an orthorhombic crystal containing Nd and Cu. As described above, at least some of the plurality of crystal grains 8 may be a cubic crystal or a tetragonal crystal. For example, at least some of the plurality of crystal grains 8 may be a tetragonal crystal containing Nd and Ga. For example, at least some of the plurality of crystal grains 8 may be an Nd-rich phase (e.g., NdFe 13 It may be a phase containing Ga.

[0041] The composition of the multiple crystal grains 8 may be distinguished from the composition of the multiple main phase particles 4 and other components based on the composition. The composition of the multiple crystal grains 8 may be measured using an energy dispersive X-ray spectroscopy (EDS) device attached to a scanning transmission electron microscope (STEM) or a scanning electron microscope (SEM). For example, a cross-sectional image of the hot-worked magnet 2 may be taken using STEM or SEM, and the composition of the multiple crystal grains 8 may be measured using EDS on the cross-sectional image. Furthermore, the multiple crystal grains 8 exposed in the cross-section of the hot-worked magnet 2 may be distinguished from the multiple main phase particles 4 and other components using elemental mapping using EDS. The composition of the multiple main phase particles 4 and other components may also be measured using the above method. Note that the same location as the TEM image can be observed using STEM using a sample observed using TEM. In other words, the composition at the location where the zone axis and angle θ were measured using TEM can be measured using STEM-EDS.

[0042] The grain boundary phase 6 may contain an oxide of the rare earth element R. At least a part or all of the plurality of crystal grains 8 may be an oxide of the rare earth element R. For example, the oxide of the rare earth element R may be at least one of Nd2O3 having a hexagonal crystal structure and NdO having a face-centered cubic structure. The oxide of the rare earth element R may be a type of R-rich phase described below. The grain boundary phase 6 may contain metallic neodymium (simple Nd) having a hexagonal close-packed structure. At least some or all of the plurality of crystal grains 8 may be metallic neodymium having a hexagonal close-packed structure. The metallic neodymium may be a type of R-rich phase described below. The plurality of crystal grains 8 containing the rare earth element R and the element M may be one type of R-rich phase described below. The grain boundary phase 6 may include an R-rich phase. The R-rich phase includes at least a rare earth element R. For example, the R-rich phase may include Nd as the rare earth element R. The R-rich phase may further include one or more other rare earth elements in addition to Nd as the rare earth element R. The R-rich phase may further include one or more elements other than the rare earth element R. The R-rich phase may include at least one of the rare earth element R alone, an alloy containing the rare earth element R, and a metal compound containing the rare earth element R. The concentration of the rare earth element R (unit: atomic %) in the R-rich phase may be higher than the average concentration of the rare earth element R in the main phase particles 4. The concentration of R in the R-rich phase may be higher than the average concentration of the rare earth element R in the cross section 2cs. When the hot-worked magnet 2 includes multiple rare earth elements R, the concentration of the rare earth element R may be the sum of the concentrations of the multiple rare earth elements R. The grain boundary phase 6 may further include a paramagnetic phase having a higher content of the transition metal element T than the plurality of crystal grains 8. For example, the content of the transition metal element T in the paramagnetic phase may be 60% by mass or more and 100% by mass or less. The paramagnetic phase may further include a rare earth element R.

[0043] The area fraction AR (phase fraction) of the cross section of the multiple crystal grains 8 in the cross section 2cs of the hot-processed magnet 2 may be 3.0% or more and 8.0% or less. The cross section 2cs where the area fraction is measured is approximately or completely parallel to the easy axis direction C of the hot-processed magnet 2. When the area fraction AR is 3.0% or more, the coercivity and squareness ratio are likely to increase. When the area fraction AR is 8.0% or less, the coercivity is likely to increase and the decrease in remanence due to the multiple crystal grains 8 is likely to be suppressed. Because the coercivity and squareness ratio are likely to increase and the decrease in remanence is likely to be suppressed, the area fraction AR may be 3.2% or more and 6.3% or less. The area fraction AR may be expressed as Acr / Acs (unit: %). Acr is the sum of the cross-sectional areas of multiple crystal grains 8. Acs is the area of ​​the cross section where Acr is measured. The cross section where Acr is measured may be the entire or a part of the cross section 2cs of the hot-processed magnet 2. In other words, Acs may be the entire area of ​​the cross section 2cs of the hot-processed magnet 2, or it may be the area of ​​a part of the cross section 2cs. The total area Acr of the cross sections of the plurality of crystal grains 8 may be measured by the following method. An image of the cross section 2cs of the hot-worked magnet 2 is taken using a TEM or SEM. A monochrome image is obtained by thresholding (binarizing) the image of the cross section 2cs using image analysis software. By adjusting the threshold value of the binarization process to an appropriate value, the multiple crystal grains 8 in the monochrome image can be distinguished from the multiple main phase particles 4 and other component compositions based on their contrast. Furthermore, the cross-sectional outline of each of the multiple crystal grains 8 is identified using the image analysis software, and the cross-sectional area of ​​each of the multiple crystal grains 8 is measured using the image analysis software. The total cross-sectional area Acr of the multiple crystal grains 8 is calculated from the cross-sectional area of ​​each of the multiple crystal grains 8. The image analysis software may be ImageJ, a public domain image analysis software, or other commercially available image analysis software.

[0044] For example, the volume ratio of the multiple main phase particles 4 (the volume ratio of all main phase particles 4 in the hot-worked magnet 2) may be 80% by volume or more and less than 100% by volume, or 92% by volume or more and 97% by volume or less.

[0045] As shown in FIG. 2 , the width W (e.g., the average value of the width W) of the grain boundary phase 6, which includes one or more crystal grains 8 in contact with one or more main phase grains 4, may be 4 nm or more and 500 nm or less in the direction of the easy axis C of magnetization of the hot-worked magnet 2. In other words, the width W of the grain boundary phase 6, which is located between a pair of main phase grains 4 and includes one or more crystal grains 8, may be 4 nm or more and 500 nm or less in the direction of the easy axis C of magnetization of the hot-worked magnet 2. When the width W of the grain boundary phase 6 is 4 nm or more, one or more crystal grains 8 (crystalline nonmagnetic phase) are likely to be formed in the grain boundary phase 6, which tends to increase the coercivity and squareness ratio of the hot-worked magnet 2. When the width W of the grain boundary phase 6 is 500 nm or less, the volume of the grain boundary phase 6, which does not have hard magnetic properties, is appropriately suppressed, which tends to suppress a decrease in the remanence of the hot-worked magnet 2. The width W of the grain boundary phase 6 may be 7.1 nm or more and 27.0 nm or less, or 7.5 nm or more and 27.0 nm or less, because the coercive force and squareness ratio are likely to increase and the decrease in remanence is likely to be suppressed.

[0046] One or more main phase particles 4 (secondary particles) in contact with one or more crystal grains 8 may include at least one of columnar crystals and equiaxed crystals. For example, as shown in FIGS. 3A and 3B, one secondary particle 4b may include multiple columnar crystals 4C, multiple flat main phase particles 4 (primary particles), and multiple equiaxed crystals 4E. The columnar crystals 4C in the secondary particles 4b may extend along the easy axis C. The flat main phase particles 4 (primary particles) in the secondary particles 4b may extend along the AB direction perpendicular to the easy axis C. The equiaxed crystals 4E may be referred to as isotropic crystals in terms of shape and crystal orientation. The columnar crystals 4C tend to be located near one surface of the flat secondary particles 4b. The equiaxed crystals 4E tend to be located near the other surface of the flat secondary particles 4b. The flat main phase particles 4 (primary particles) tend to be located between the columnar crystals 4 C and the equiaxed crystals 4 E. One columnar crystal 4 C and one equiaxed crystal 4 E may each be one main phase particle (primary particle). The columnar crystals 4C and the equiaxed crystals 4E may originate from the alloy ribbon, which is the raw material of the hot-processed magnet 2. In other words, the alloy ribbon may be a precursor of the secondary particles 4b. The alloy ribbon is produced by a rapid solidification method, which will be described later. In the rapid solidification method, a molten metal containing multiple elements that constitute the hot-processed magnet 2 is brought into contact with the surface of a chill roll and cooled. As a result, the molten metal solidifies to form an alloy ribbon. At the portion of the molten metal that contacts the surface of the chill roll (contact portion), the molten metal is rapidly cooled, and a chill layer (e.g., a layer containing a plurality of minute crystal grains on the nanoscale) is likely to be formed near the surface of the alloy ribbon. The plurality of crystal grains in the chill layer are heated in the hot forming process or the hot plastic working process. As a result, the growth of coarse crystal grains derived from the chill layer progresses rapidly near the surface of the alloy ribbon, and coarse equiaxed crystals 4E are likely to be formed near the surface of the flat secondary particles 4b. On the other hand, the portion of the molten metal located behind the contact portion (non-contact portion) does not contact the chill roll and is farthest from the surface of the chill roll, so the cooling rate of the non-contact portion is slower than the cooling rate of other portions of the molten metal. Therefore, a temperature gradient of the molten metal occurs in the direction from the non-contact portion to the contact portion. Due to the temperature gradient of the molten metal, during the solidification and crystallization of the molten metal, a plurality of columnar crystals 4C extending in the thickness direction of the alloy ribbon are likely to be formed near the surface of the alloy ribbon (the back side of the surface where the chill layer, which is a precursor of the equiaxed crystals 4E, is located). The cooling rate of the portion of the molten metal between the contact and non-contact portions (inside the molten metal) is lower than that of the contact portion but higher than that of the non-contact portion. Therefore, multiple crystal grains with diameters of several tens of nanometers (crystal grains larger than those in the chill layer) are likely to form inside the molten metal. During the hot plastic working process, each crystal grain formed inside the molten metal grows anisotropically along the AB direction, which is perpendicular to the easy axis direction C of magnetization, and becomes a flat main phase particle 4. The inventors speculate that the columnar crystals 4C and the equiaxed crystals 4E are easily formed because the multiple minute crystal grains and multiple coarse crystal grains contained in the alloy ribbon are difficult to orient by normal grain boundary sliding during the hot plastic working process. A plurality of crystal grains 8 whose zone axes cza are oriented along one direction (orientation direction D) tend to be present near columnar crystals 4C or equiaxed crystals 4E. That is, the zone axes cza of a plurality of crystal grains 8 in contact with one or more columnar crystals 4C or equiaxed crystals 4E may be oriented along one direction (orientation direction D). A grain boundary phase 6 may be present between a plurality of main phase particles 4 included in one secondary particle 4b. The grain boundary phase 6 in the secondary particle 4b may include a plurality of crystal grains 8. A plurality of crystal grains 8 in the secondary particle 4b may be in contact with one or more main phase particles 4 in the secondary particle 4b. The zone axes cza of a plurality of crystal grains 8 in contact with one or more main phase particles 4 in the secondary particle 4b may be oriented along one direction (orientation direction D).

[0047] 2, the main phase grains 4 observed in the cross section 2cs parallel to the easy axis direction C may be flat. In other words, the main phase grains 4 observed in the cross section 2cs may be plate-shaped. The flat main phase grains 4 may be stacked along the easy axis direction C.

[0048] The width S of each of the plurality of main phase particles 4 (primary particles) in the easy axis direction C may be smaller than the width L of each of the plurality of main phase particles 4 in the AB direction perpendicular to the easy axis direction C. In other words, the length (S) of the minor axis of each main phase particle 4 may be smaller than the length (L) of the major axis of each main phase particle 4. The width S of each main phase particle 4 in the easy axis direction C (e.g., the average value of the width S) may be 20 nm or more and 200 nm or less, 65 nm or more and 77 nm or less, or 66 nm or more and 75 nm or less. The width L of each main phase particle 4 in the AB direction perpendicular to the easy axis direction C (e.g., the average value of the width L) may be 100 nm or more and 1000 nm or less. For example, the aspect ratio L / S of each of the plurality of main phase particles 4 (e.g., the average value of the aspect ratio L / S) may be 2 or more and 10 or less. When the aspect ratio L / S is 2 or more, the c-axis of the main phase grains 4 is easily oriented in the direction of the easy axis of magnetization C, and the coercive force is easily increased. An aspect ratio L / S of 2 or more is advantageous in that the main phase grains 4 (R2T 14 This shows that anisotropic grain growth of the main phase grains 4 (crystals of B) has progressed sufficiently. Since there is a limit to the anisotropic grain growth of the main phase grains 4 in the hot plastic working process, it is difficult for the aspect ratio L / S to exceed 10. The size of each of the plurality of crystal grains 8 may be approximately the same as the size of each of the plurality of main phase particles 4. The size of each of the plurality of crystal grains 8 may be smaller than the size of each of the plurality of main phase particles 4. The shape of each of the plurality of crystal grains 8 is not limited.

[0049] The shape of the main phase particles 4 in the cross section 2cs is not limited to a rectangle. The shape of the main phase particles 4 in the cross section 2cs may be distorted. The shape of the main phase particles 4 in the cross section 2cs may not be uniform. When the shape of the main phase particles 4 in the cross section 2cs is distorted, the shape of the main phase particles 4 may be approximated by a rectangle with the smallest area among the rectangles circumscribing the main phase particle 4. The rectangle may be rectangular. The length of the short side of this rectangle may be considered to be the length (S) of the minor axis of the main phase particle 4, and the length of the long side of the rectangle may be considered to be the length (L) of the major axis of the main phase particle 4. The average value of the length of the minor axes of the main phase particles 4 may be calculated from the measured values ​​of the lengths of the minor axes of all the main phase particles 4 present in the backscattered electron image of the cross section 2cs taken by SEM. The average value of the length of the major axes of the main phase particles 4 may also be calculated from the measured values ​​of the lengths of the major axes of all the main phase particles 4 present in the backscattered electron image. However, the dimensions of the main phase particles 4 that extend beyond the backscattered electron image are excluded from the calculation of the average value. For example, the maximum dimensions of the backscattered electron image used to measure the lengths of the minor and major axes of the main phase particles 4 may be 120 μm long × 80 μm wide, or 80 μm long × 120 μm wide. Representative locations within these backscattered electron images taken at low magnification may be selected, and backscattered electron images of each location may be taken at high magnification. Then, average values ​​of the major and minor axes may be calculated from the lengths of the major and minor axes of all the main phase particles 4 measured within the high-magnification backscattered electron images. Image analysis software (e.g., the above-mentioned ImageJ) may be used to identify the shape (contour) of the main phase particles 4 and measure the dimensions of the main phase particles 4 (rectangles circumscribing the main phase particles 4).

[0050] Each main phase particle 4 may be composed of a surface layer and a core covered by the surface layer. The surface layer may be referred to as a shell, and the core as a core. The surface layer of each main phase particle 4 may contain at least one heavy rare earth element selected from Tb and Dy. The surface layer of each of all main phase particles 4 may contain at least one heavy rare earth element selected from Tb and Dy. The surface layer of some of all main phase particles 4 may contain at least one heavy rare earth element selected from Tb and Dy. When the surface layer contains a heavy rare earth element, the anisotropy magnetic field is likely to increase locally near the grain boundaries, making it difficult for magnetization reversal nuclei to occur near the grain boundaries. As a result, the coercivity of the hot-worked magnet 2 at high temperatures (e.g., 100 to 200°C) is increased. Since the hot-processed magnet 2 tends to have both high remanence (Br) and high coercivity, the total concentration of heavy rare earth elements in the surface layer may be higher than the total concentration of heavy rare earth elements in the center.

[0051] For example, the dimension of the hot-processed magnet 2 in the easy axis direction C may be several mm to several hundred mm, or several tens of mm to several hundred mm. For example, the dimension of the hot-processed magnet 2 in the AB direction may be several mm to several hundred mm, or several tens of mm to several hundred mm.

[0052] The overall composition of the hot-processed magnet 2 is described below. However, the composition of the hot-processed magnet 2 is not limited to the composition below. The content of each element in the hot-processed magnet 2 may be outside the following ranges.

[0053] The content of the rare earth element R in the hot-processed magnet 2 may be 26.00% by mass or more and 32.00% by mass or less, or 28.00% by mass or more and 32.00% by mass or less. If the content of the rare earth element R is 26.00% by mass or more, a liquid phase (R-rich phase) is likely to form at the grain boundaries during the manufacturing process of the hot-processed magnet 2, which tends to orient the main phase particles 4 due to grain boundary sliding and increase the coercive force of the hot-processed magnet 2. On the other hand, if the content of R is 32.00% by mass or less, the formation of an excessive liquid phase (R-rich phase) is suppressed, which tends to increase the volume ratio of the main phase.

[0054] Because the residual magnetic flux density and coercive force tend to increase, the total proportion of Nd and Pr in all rare earth elements R may be 80 atomic % or more and 100 atomic % or less, or 95 atomic % or more and 100 atomic % or less.

[0055] The total content of Tb and Dy in the hot-processed magnet 2 may be 0.00% by mass or more and 5.00% by mass or less. When the hot-processed magnet 2 contains at least one heavy rare earth element selected from Tb and Dy, the magnetic properties (particularly the coercive force at high temperatures) of the hot-processed magnet 2 tend to improve. However, the hot-processed magnet 2 does not need to contain Tb and Dy.

[0056] The B content in the hot-deformed magnet 2 may be 0.77% by mass or more and 1.15% by mass or less. When the B content is 0.77% by mass or more, the TbCu7-type R2Fe 17 When the B content is 1.15 mass % or less, the formation of heterogeneous phases such as R is appropriately suppressed, and the coercive force is easily increased. 1+ε The formation of heterophases such as Fe4B4 (Boride) is suppressed, and the coercive force is likely to increase. When the B content is within the above range, the squareness ratio of the hot-processed magnet 2 tends to approach 1.0.

[0057] The hot-processed magnet 2 may further contain the element M. The element M may be at least one element selected from the group consisting of Cu, Ga, Zn, Ni, and Cr. The content of the element M in the hot-processed magnet 2 may be 0.67% by mass or more and 7.30% by mass or less. When the content of the element M is 0.67% by mass or more, a plurality of nonmagnetic crystal grains 8 is likely to be formed. Furthermore, when the content of the element M is 0.67% by mass or more, a grain boundary phase with a low melting point is likely to be formed in the hot-forming process and hot plastic processing process described below, making it possible to lower the hot-processing temperature and hot plastic processing temperature, and the coercivity of the hot-processed magnet 2 is likely to be increased. When the content of the element M is 7.30% by mass or less, the formation of a plurality of nonmagnetic crystal grains 8 is appropriately suppressed, the proportion of main phase particles 4 in the hot-processed magnet 2 is increased, and the remanence of the hot-processed magnet 2 is likely to be increased.

[0058] The Cu content in the hot-processed magnet 2 may be 0.01% by mass or more and 1.50% by mass or less, or 0.04% by mass or more and 0.50% by mass or less. Having a Cu content within this range makes it easier to forge the hot-processed magnet 2, and tends to improve the coercive force, corrosion resistance, and temperature characteristics of the hot-processed magnet 2. However, the hot-processed magnet 2 does not need to contain Cu.

[0059] The Ga content in the hot-processed magnet 2 may be 0.03% by mass or more and 1.00% by mass or less, or 0.20% by mass or more and 0.80% by mass or less. When the Ga content is within this range, the formation of subphases (e.g., phases containing R, T, and Ga) is appropriately suppressed, and the remanence and coercivity of the hot-processed magnet 2 tend to increase. However, the hot-processed magnet 2 does not need to contain Ga.

[0060] The hot-processed magnet 2 may contain aluminum (Al). For example, the Al content in the hot-processed magnet 2 may be 0.01% by mass or more and 0.2% by mass or less, or 0.04% by mass or more and 0.07% by mass or less. The Al content within this range tends to improve the coercive force and corrosion resistance of the hot-processed magnet. However, the hot-processed magnet 2 does not need to contain Al.

[0061] The hot-processed magnet 2 may contain cobalt (Co). For example, the Co content in the hot-processed magnet 2 may be 0.30% by mass or more and 6.00% by mass or less, or 0.30% by mass or more and 4.00% by mass or less. When the hot-processed magnet 2 contains Co, the Curie temperature of the hot-processed magnet 2 is likely to be increased. Furthermore, when the hot-processed magnet 2 contains Co, the corrosion resistance of the hot-processed magnet 2 is likely to be improved. However, the hot-processed magnet 2 does not need to contain Co. The hot-processed magnet 2 may contain cerium (Ce). For example, the Ce content in the hot-processed magnet 2 may be 1.42 mass% or more and 14.17 mass% or less. However, the hot-processed magnet 2 does not need to contain Ce.

[0062] The remainder, excluding the above elements from the hot-processed magnet 2, may consist of only Fe, or Fe and other elements. In order for the hot-processed magnet 2 to have sufficient magnetic properties, the total content of the remaining elements other than Fe may be 5 mass% or less relative to the total mass of the hot-processed magnet 2.

[0063] The hot-processed magnet 2 may contain at least one element selected from the group consisting of silicon (Si), titanium (Ti), manganese (Mn), zirconium (Zr), vanadium (V), niobium (Nb), molybdenum (Mo), hafnium (Hf), tantalum (Ta), tungsten (W), bismuth (Bi), tin (Sn), calcium (Ca), carbon (C), nitrogen (N), oxygen (O), chlorine (Cl), sulfur (S), and fluorine (F) as other elements (e.g., inevitable impurities). For example, the total content of other elements in the hot-processed magnet 2 may be 0.001% by mass or more and 0.50% by mass.

[0064] For example, the composition of the entire hot-processed magnet 2 may be analyzed by X-ray fluorescence (XRF) analysis, inductively coupled plasma (ICP) emission spectrometry, inert gas fusion-non-dispersive infrared (NDIR) analysis, oxygen combustion-infrared absorption analysis, and inert gas fusion-thermal conductivity analysis.

[0065] For example, the hot-processed magnet 2 may be applied to motors, generators, actuators, etc. For example, the hot-processed magnet 2 may be used in various fields such as hybrid vehicles, electric vehicles, hard disk drives, magnetic resonance imaging devices (MRI), smartphones, digital cameras, flat-screen TVs, scanners, air conditioners, heat pumps, refrigerators, vacuum cleaners, washer-dryers, elevators, and wind power generators.

[0066] (Method of manufacturing hot-deformed magnets) The method for producing a hot-worked magnet according to this embodiment includes at least a ribbon production step, a hot pressing step, a hot deforming step, and an unloading step. The method for producing a hot-worked magnet may further include other steps, such as a grain boundary diffusion step, following the unloading step. However, the grain boundary diffusion step is not essential.

[0067] In order to suppress oxidation of the hot-processed magnet and its in-process products during the manufacturing process, the manufacturing method of the hot-processed magnet may be carried out in a non-oxidizing atmosphere. For example, the non-oxidizing atmosphere may be an inert gas such as argon (Ar) gas. The non-oxidizing atmosphere may further contain a reducing gas such as hydrogen gas (H) in addition to the inert gas.

[0068] The ribbon production process is a process in which alloy ribbons are produced from multiple types of raw metals by the hyper-rapid solidification method. In the hyper-rapid solidification method, molten metal in a container is sprayed onto the surface of a chill roll from a nozzle located at the tip of the container. The molten metal comes into contact with the surface of the chill roll and is instantly thrown off by the chill roll, which rotates at high speed, forming a large number of elongated ribbons. Upon contact with the surface of the chill roll, the molten metal is rapidly cooled and solidified. As a result, a large number of elongated alloy ribbons are formed. A container is placed in the direction in which the alloy ribbons are thrown off by the chill roll, and the alloy ribbons are collected into the container.

[0069] The molten metal is a metal (plurality of raw material metals) containing multiple elements that will constitute the hot-processed magnet. The multiple raw material metals may include, for example, simple rare earth elements (simple metals), alloys containing rare earth elements, pure iron, ferroboron, or alloys containing these. The multiple raw material metals may include the above-mentioned element M. The multiple raw material metals are weighed out to match the composition of the desired hot-processed magnet.

[0070] The molten metal may be obtained by heating a plurality of raw metals in a vessel by high-frequency induction heating. The temperature of the molten metal sprayed from the nozzle (spray temperature) may be, for example, about 1400°C. The rate of temperature increase until the temperature of the raw metal reaches the spray temperature may be, for example, about 20 to 100°C / second.

[0071] The surface of the chill roll may be made of a metal with high thermal conductivity, such as Cu. The temperature of the surface of the chill roll may be controlled by a coolant flowing through the chill roll. For example, if the cooling rate of the molten metal on the surface of the chill roll is about 10 5 ~10 6 The surface temperature of the cooling roll may be controlled so that the cooling rate is 0.25 °C / sec. The higher the cooling rate, the more the crystals (R2T) contained in the alloy ribbon 14 B) particle size tends to be finer, and the coercive force of the hot-processed magnet tends to be higher. The smaller the amount of molten metal sprayed onto the surface of the chill roll per unit time, the thinner the molten metal adhering to the surface of the chill roll, the higher the cooling rate, and the thinner the alloy ribbon. The higher the peripheral speed of the chill roll, the thinner the molten metal adhering to the surface of the chill roll, the higher the cooling rate, and the thinner the alloy ribbon. The thickness of the main phase particles in the direction of the easy axis of magnetization (the length of the minor axis of the main phase particles) depends on the thickness of the alloy ribbon (and the pulverization and classification of the alloy ribbon). The thinner the alloy ribbon, the smaller the thickness (particle size) of the main phase particles, and the higher the coercive force of the hot-processed magnet. For example, the thickness of the alloy ribbon may be 20 μm to 60 μm, or 30 μm to 50 μm. For example, the width of the alloy ribbon may be 1.0 mm to 5.0 mm.

[0072] After the ribbon preparation step, a pulverization / classification step may be carried out. The pulverization / classification step involves pulverizing the alloy ribbon using a pulverizer to produce coarse powder, and then classifying the coarse powder to recover an alloy powder having a predetermined particle size and aspect ratio. The alloy powder is a precursor of the main phase particles contained in the hot-worked magnet. The shape of each alloy particle constituting the alloy powder may be plate-like or flake-like. The alloy ribbon may be pulverized by at least one of a cutter mill and a propeller mill, for example. The coarse powder may be classified using a sieve. The particle size and particle size distribution of the alloy powder obtained by classification may be measured, for example, by a laser diffraction / scattering method. The particle size of the alloy powder obtained by classification may be, for example, 60 μm to 2800 μm or 150 μm to 2800 μm.

[0073] The hot compacting step is a step of forming a compact by applying pressure to an alloy ribbon (alloy powder) while heating it. For example, the alloy powder may be compressed in a die while being heated in the die. Pressurizing the alloy powder reduces voids between the alloy powder, resulting in a dense compact. Furthermore, heating the alloy powder during pressurization forms a liquid phase (an R-rich phase, such as an Nd-rich phase) on the surface of the alloy powder, and the liquid phase fills the voids (grain boundaries) between the alloy powder. The liquid phase lubricates the alloy powder, making it easier to compress the alloy powder and more likely to produce a dense compact. A cold compacting step may be performed before the hot compacting step. In the cold compacting step, the alloy powder may be compressed at room temperature to form a compact. The compact obtained by the cold compacting step may be densified by applying pressure to the compact obtained by the cold compacting step while being heated in the hot compacting step. For example, the temperature of the alloy powder in the hot compacting step (hot compacting temperature) may be 550°C or higher and 800°C or lower. If the hot compaction temperature is too low, a sufficient liquid phase is not formed on the surface of the alloy powder, making it difficult to densify the compact. If the hot compaction temperature is too high, the crystals (R2T) constituting the alloy powder are 14 B) grain growth proceeds excessively, and the coercivity of the hot-processed magnet tends to decrease. For example, the pressure applied to the alloy powder in the hot-compacting step (hot-compacting pressure) may be 50 MPa or more and 200 MPa or less. For example, the time during which the hot-compacting temperature and hot-compacting pressure are maintained within the above ranges (hot-compacting time) may be several tens of seconds or more and several hundred seconds or less.

[0074] After the hot forming step, a hot plastic working step is carried out. In the hot plastic working step, a plurality of main phase grains (R2T) whose c-axes (axis of easy magnetization) are oriented in a predetermined direction are formed by hot extrusion of the compact obtained by the hot forming step. 14 This is a process for obtaining a magnet base material containing R-rich phases (crystal grains of R). For example, in a hot plastic working process, a compact is extruded from a die while being heated. In the die, the grain boundary phase in the heated compact liquefies, forming a liquid phase (R-rich phase). At the same time, stress acts on the compact in a predetermined direction, distorting each alloy grain that makes up the compact. The formation of the liquid phase and the distortion of the alloy grains cause anisotropic growth of the crystal grains in a direction perpendicular to their c-axes. The liquid phase also lubricates each crystal grain, exerting a force on each crystal grain in response to the stress. As a result, the crystal grains rotate due to grain boundary sliding, and the c-axes of each crystal grain (main phase grain) become aligned approximately parallel to the stress direction. In other words, multiple flat main phase grains extending in a direction approximately perpendicular to the c-axes are stacked along the stress direction. For example, the temperature of the compact in the hot plastic working step (hot plastic working temperature) may be 700°C or higher and lower than 900°C, or 700°C or higher and 850°C or lower. If the hot plastic working temperature is too low, liquid phases (R-rich phases such as Nd-rich phases) are unlikely to form at the grain boundaries within the compact, the grains are unlikely to grow, and grain rotation due to grain boundary sliding is unlikely to occur. As a result, the average length of the minor axes of the main phase grains is likely to be less than 20 nm, and the c-axes of each main phase grain (crystal grain) are unlikely to be oriented approximately parallel to the stress direction. If the hot plastic working temperature is too high (for example, if the hot plastic working temperature is 900°C or higher), the liquid phase (R-rich phase) will exude excessively from each alloy particle and segregate to the surface of each alloy particle and the interfaces between alloy particles, and most of the liquid phase will be consumed in the grain growth of the crystal grains. Because most of the liquid phase is consumed in the grain growth of the crystal grains, the grain growth of the main phase particles (crystal grains) will proceed abnormally, and coarse main phase particles will likely be formed, with the average length of the minor axis of the main phase particles likely exceeding 200 nm. The coarse main phase particles will be difficult to orient in the direction of the easy axis of magnetization. For example, the extrusion speed of the compact during hot extrusion molding may be 0.01 mm / sec or more and 9.9 mm / sec or less. If the extrusion speed is too high (e.g., 10 mm / sec or more), the anisotropic growth of the main phase particles (crystal grains) in the compact does not proceed sufficiently, and the average length of the minor axes of the main phase particles (primary particles) tends to be less than 20 nm. In other words, if the extrusion speed is too high, the compact will be extruded from the die before the anisotropic growth of the crystal grains in the compact has proceeded sufficiently. As a result, it is difficult for the c-axes of the main phase particles (crystal grains) to be oriented parallel to the stress direction. For example, the pressure applied to the compact in the hot plastic working step (hot plastic working pressure) may be 35 MPa or more and 50 MPa or less. If the hot plastic working pressure exceeds 50 MPa, it is difficult for multiple crystal grains 8 to be formed, and it is difficult for the zone axes cza of the multiple crystal grains 8 to be oriented along one direction (orientation direction D). For example, the time (hot plastic working time) during which the hot plastic working temperature and hot plastic working pressure are maintained within the above ranges may be several tens of seconds.

[0075] For example, as shown in FIG. 5, a mold 10 used in a hot plastic working process has a cylindrical shape. That is, the mold 10 has a pair of circular end faces (a starting end face 10a and a terminal end face 10b) and a cylindrical side face. A cavity 12 formed in the mold 10 penetrates the mold 10 from the starting end face 10a to the terminal end face 10b. That is, the inlet of the cavity 12 (the inlet for the compact 20) opens at the starting end face 10a, and the outlet of the cavity 12 (the extrusion port for the compact 20) opens at the terminal end face 10b. The compact 20 is introduced into the inlet of the cavity 12 at the starting end face 10a. The hot forming pressure applied to the compact 20 by the upper ram of the press machine pushes the compact 20 out of the outlet of the cavity 12 at the terminal end face 10b. That is, the direction from the starting end face 10a to the terminal end face 10b is the extrusion direction Z of the formed body 20, and the direction of the hot plastic working pressure is equal to the extrusion direction Z. The starting end face 10a and the terminal end face 10b are planes parallel to each other, and the extrusion direction Z is perpendicular to the starting end face 10a and the terminal end face 10b. The shape of the cavity 12 in a direction perpendicular to the extrusion direction Z (a direction parallel to the starting end face 10a and the terminal end face 10b) is a quadrilateral with all four corners being right angles. A pair of opposing sides of this quadrilateral is referred to as a first side, and the other pair of opposing sides of the quadrilateral is referred to as a second side. The length xa of the first side at the starting end surface 10a (the entrance of the cavity 12) is longer than the length ya of the second side at the starting end surface 10a (the entrance of the cavity 12). The length xa of the first side gradually decreases along the extrusion direction Z and finally coincides with the length xb of the first side at the terminal end surface 10b (the outlet of the cavity 12). In other words, the length xb of the first side at the terminal end surface 10b (the outlet of the cavity 12) is smaller than the length xa of the first side at the starting end surface 10a (the entrance of the cavity 12). In contrast, the length ya of the second side gradually increases along the extrusion direction and eventually coincides with the length yb of the second side at the terminal end surface 10b (extrusion outlet of the cavity 12). In other words, the length yb of the second side at the terminal end surface 10b (extrusion outlet of the cavity 12) is greater than the length ya of the second side at the starting end surface 10a (entrance of the cavity 12). As a result of the decrease in the length xa of the first side along the extrusion direction Z and the increase in the length ya of the second side along the extrusion direction Z, the length xb of the first side at the outlet of the cavity 12 becomes smaller than the length yb of the second side at the outlet of the cavity 12. Furthermore, due to the change in the lengths of the first and second sides along the extrusion direction Z, the opening area of ​​the cavity 12 in the direction perpendicular to the extrusion direction Z gradually decreases along the extrusion direction Z. In other words, the opening area of ​​the outlet of the cavity 12 at the end face 10b is smaller than the opening area of ​​the inlet of the cavity 12 at the start face 10a. Due to the above-described changes in the shape and opening area of ​​the cavity 12 along the extrusion direction Z, stress that is approximately or completely parallel to the first side of the cavity 12 acts on the compact 20 passing through the cavity 12. The stress that the cavity 12 exerts on the compact 20 causes grain boundary sliding and rotation of the main phase grains within the compact 20. As a result, the c-axes of the main phase grains are oriented along the stress direction (direction X of the first side). In other words, the direction of the easy axis of magnetization C of the magnet base material obtained by hot extrusion molding approximately or completely coincides with the direction of the first side (direction X) at the terminal end surface 10b.

[0076] The unloading step following the hot plastic working step includes a first step and a second step following the first step. In the first step, the magnet substrate is heated while being pressed with a pressure p. In the second step, the magnet base material is naturally cooled while being pressurized with a pressure p, and after the magnet base material has naturally cooled, the pressure p applied to the magnet base material is released. In both the first and second steps, the magnet substrate is pressed by being sandwiched between a pair of rams of a biaxial press. The pressure p applied to the magnet substrate is approximately or completely parallel to the magnetization easy axis direction C of the magnet substrate. In the first step, the temperature of the pair of rams is maintained at a predetermined temperature (unloading temperature t), and the magnet substrate is heated by the pair of rams. The pressure p applied to the magnet base material in the unloading step may be 35 MPa or more and 70 MPa or less, or 35 MPa or more and 50 MPa or less. If the pressure p exceeds 70 MPa, it is difficult for multiple crystal grains 8 to be formed, and it is difficult for the zone axes cza of the multiple crystal grains 8 to be oriented along one direction (orientation direction D). Even if the unloading step is not performed, it is difficult for multiple crystal grains 8 to be formed, and it is difficult for the zone axes cza of the multiple crystal grains 8 to be oriented along one direction (orientation direction D). For example, the unloading temperature t may be 25°C or more and 500°C or less. The time during which the magnet base material is pressurized with the pressure p and the temperature of the magnet base material is maintained at the unloading temperature t may be 60 seconds or more and 600 seconds or less.

[0077] The magnet base material obtained by the above steps may be the finished hot-worked magnet. The magnet base material that has undergone the grain boundary diffusion step described below may be the finished hot-worked magnet.

[0078] After the unloading step, the following grain boundary diffusion step may be performed. The grain boundary diffusion step is a step of attaching a diffusion material containing a heavy rare earth element to the surface of the magnet substrate and heating the diffusion material and the magnet substrate. By heating the magnet substrate with the attached diffusion material, the heavy rare earth element in the diffusion material diffuses from the surface of the magnet substrate to the interior of the magnet substrate. Inside the magnet substrate, the heavy rare earth element diffuses through the grain boundaries to the vicinity of the surface of the main phase particles. Near the surface of the main phase particles, some of the light rare earth elements (such as Nd) are substituted with heavy rare earth elements. By localizing the heavy rare earth element near the surface and at the grain boundaries of the main phase particles, the anisotropy field becomes locally large near the grain boundaries, making it difficult for nuclei of magnetization reversal to be generated near the grain boundaries. As a result, a hot-worked magnet with high coercivity is obtained.

[0079] For example, the temperature (diffusion temperature) of the diffusion material and magnet base material in the grain boundary diffusion step may be 550° C. or higher and 900° C. or lower. For example, the time (diffusion time) during which the diffusion temperature is maintained within the above range may be 1 minute or higher and 1440 minutes or lower.

[0080] The diffusing material may contain at least one heavy rare earth element selected from Tb and Dy. The diffusing material may further contain at least one light rare earth element selected from Nd and Pr in addition to the heavy rare earth element. The diffusing material may be, for example, a metal consisting of one of the above elements, a hydride of one of the above elements, an alloy containing multiple types of the above elements, or a hydride of the alloy. The diffusing material may be a powder. In the grain boundary diffusion process, a slurry containing the diffusing material and an organic solvent may be applied to the surface of the magnet substrate. In the grain boundary diffusion process, the surface of the magnet substrate may be covered with a sheet containing the diffusing material and a binder. In the grain boundary diffusion process, the surface of the magnet substrate may be covered with an alloy foil (ribbon) composed of the diffusing material. The diffusing material does not need to contain the above-mentioned element M.

[0081] In order to promote the diffusion of the diffusing material, the surface of the magnet base material may be polished before the grain boundary diffusion step. In order to remove the diffusing material remaining on the surface of the magnet base material after the grain boundary diffusion step, the surface of the magnet base material may be polished after the grain boundary diffusion step.

[0082] The size and shape of the magnet substrate may be adjusted by cutting and polishing the magnet substrate. A passive layer may be formed on the surface of the magnet substrate by oxidation or chemical treatment of the surface of the magnet substrate. The surface of the magnet substrate may be covered with a protective film such as a resin film. The passive layer or protective film improves the corrosion resistance of the hot-worked magnet.

[0083] The present disclosure is not necessarily limited to the above-described embodiments. Various modifications of the present disclosure are possible without departing from the spirit of the present disclosure, and these modifications are also included in the present disclosure. [Example]

[0084] The present disclosure will be described in detail with reference to the following examples and comparative examples, but the present disclosure is not limited to the following examples.

[0085] <Production of hot-deformed magnets> Example 1 Each step in Example 1 below was carried out in a non-oxidizing atmosphere (Ar gas).

[0086] In the ribbon production step, an alloy powder (alloy ribbon) was produced from a molten metal containing a plurality of raw material metals by an ultra-rapid solidification method. The molten metal used in the ribbon production step contained Nd, Fe, Co, Ga, Cu, and B. Ga and Cu correspond to the element M described above. The contents of each element in the molten metal in Example 1 were the values ​​shown in Table 1 below.

[0087] In the hot compacting process, the alloy powder was compressed in a die while being heated in the die, to produce a compact. The compact was a rectangular parallelepiped. The dimensions of the compact were 22 mm x 11 mm x 30 mm. The hot compacting temperature was 660°C. The hot compacting pressure was 100 MPa. The hot compacting time was 240 seconds.

[0088] The hot plastic working process was carried out following the hot forming process. In the hot plastic working process, a magnet substrate was produced by hot extrusion molding of a compact using the above-mentioned mold 10 (mold 10 shown in Figure 5). The outline of the hot plastic working process was as described in the above embodiment. Both the entrance to the cavity 12 of the mold 10 and the exit to the cavity 12 of the mold 10 were rectangular. The length xa of the first side of the entrance of the cavity 12 was 22.0 mm. The length ya of the second side of the entrance of the cavity 12 was 11.0 mm. The length xb of the first side of the outlet of the cavity 12 was 5.5 mm. The length yb of the second side of the outlet of the cavity 12 was 30.0 mm. The plastic working rate (unit: %) in the hot plastic working process is defined as {(xa-xb) / xa} x 100. In other words, the plastic working rate was {(22.0-5.5) / 22.0} x 100, or 75%. The temperature of the die 10 in the hot plastic working step was 750° C. The extrusion speed in the hot extrusion was 0.1 mm / sec. The hot plastic working pressure (maximum pressure Pmax) was the value shown in Table 1 below.

[0089] An unloading process was carried out following the hot plastic working process. The outline of the unloading process was as described in the above embodiment. The pressure p applied to the magnet base material in the unloading process was the value shown in Table 1 below. The unloading temperature t was 480°C. The time during which the magnet base material was pressed at the pressure p and heated at the unloading temperature t was 300 seconds.

[0090] No grain boundary diffusion step using a diffusion agent was performed.

[0091] The hot-worked magnet of Example 1 was produced by the above method.

[0092] (Examples 2 to 9, Comparative Examples 1 to 3) The contents of each element in the molten metals of Examples 2 to 9 and Comparative Examples 1 to 3 were the values ​​shown in the following Table 1. Only the molten metal of Example 4 contained Pr and Dy in addition to Nd, Fe, Co, Ga, Cu, and B.

[0093] The maximum pressure Pmax in the hot plastic working step in each of Examples 2 to 9 and Comparative Examples 1 to 3 was the value shown in Table 1 below.

[0094] The pressure p in the unloading step for each of Examples 2 to 9 and Comparative Example 2 was the value shown in the following Table 1. The unloading step was not carried out for each of Comparative Examples 1 and 3. In other words, in Comparative Examples 1 and 3, after the hot plastic working step, the magnet base material was allowed to cool naturally without being heated or pressurized.

[0095] The hot-worked magnets of Examples 2 to 9 and Comparative Examples 1 to 3 were produced in the same manner as in Example 1, except for the above-mentioned points.

[0096] <Analysis of hot-processed magnets> A backscattered electron image of the cross section of the hot-processed magnet of Example 1 was taken using a scanning electron microscope (SEM). Furthermore, the composition of the cross section of the hot-processed magnet was analyzed using an energy dispersive X-ray spectrometer (SEM-EDS) attached to the SEM. The cross sections analyzed by SEM and SEM-EDS were parallel to the easy axis direction C of the hot-processed magnet. In other words, the backscattered electron image of the cross section of the hot-processed magnet was parallel to the easy axis direction C. Multiple backscattered electron images of Example 1 are shown in Figure 6, (a) in Figure 7, and (b) in Figure 7.

[0097] The results of the above analyses using SEM showed that the hot-deformed magnets had the following characteristics: The composition of the hot-deformed magnet was consistent with the composition of the molten metal (composition shown in Table 1 below). Hot-deformed magnets have many main phase particles (Nd2T 14 B grains). The hot-worked magnet contained a grain boundary phase located between multiple main phase grains. Each of the main phase particles contained at least Nd as R and at least Fe as T. Numerous flat main phase particles were observed in the cross section of the hot-worked magnet. The minor axes of the flat main phase grains were approximately parallel or completely parallel to the direction C of the easy axis of magnetization. The major axes of the flat main phase grains were approximately or completely perpendicular to the direction C of the easy axis of magnetization. Many flat main phase grains were stacked along the easy axis direction C. As shown in region 7a in the backscattered electron image of Figure 7(a), multiple equiaxed crystals (main phase particles) were observed in the cross section of the hot-deformed magnet. The multiple equiaxed crystals were surrounded by grain boundary phases. At least some of the equiaxed crystals were in contact with crystal grains (crystal grains containing Nd and Cu) described below. As shown in region 7b in the backscattered electron image of Figure 7(b), multiple columnar crystals (main phase particles) extending along the easy axis direction C were observed in the cross section of the hot-deformed magnet. At least some of the columnar crystals were in contact with crystal grains (crystal grains containing Nd and Cu) described below.

[0098] The average width S (length of the minor axis) of multiple main phase particles (primary particles) in the easy axis direction C of magnetization was measured in a backscattered electron image of the cross section of the hot-worked magnet using the following method. The vertical width (width in the easy axis direction C) of the backscattered electron image where the average width S was measured was 2.54 μm, and the horizontal width of the backscattered electron image where the average width S was measured was 1.90 μm. Multiple representative locations within the backscattered electron image were selected, and backscattered electron images of each location were taken at high magnification. The minor axis lengths of the main phase particles (primary particles) present in the high-magnification backscattered electron image were measured. The shape of each main phase particle was approximated by the rectangle with the smallest area among the rectangles circumscribing the main phase particle. The length of the long side of this rectangle was considered to be the length of the major axis of the main phase particle, and the length of the short side of the rectangle was considered to be the length of the minor axis of the main phase particle. The average values ​​(unit: nm) of the widths S (lengths of the minor axes) of the main phase particles (primary particles) in Example 1 are shown in Table 2 below.

[0099] A TEM image of the cross section of the hot-processed magnet of Example 1 was taken using a transmission electron microscope (TEM). Furthermore, the cross section of the hot-processed magnet (the cross section from which the TEM image was taken) was further observed using a STEM, and the composition of the cross section was analyzed using an energy-dispersive X-ray spectroscopy (STEM-EDS) device attached to the STEM. The cross section analyzed by TEM and STEM-EDS was parallel to the easy axis direction C of the hot-processed magnet. In other words, the TEM image of the cross section of the hot-processed magnet was parallel to the easy axis direction C. The TEM image of Example 1 is shown in FIG. 8. In Figure 8, multiple asterisks (*) numbered 1 to 7 indicate the positions of measurement points 1 to 7. The composition of each of measurement points 1 to 7 was analyzed by STEM-EDS. Electron beam diffraction patterns were measured at each of measurement points 1 to 7 by selected area electron diffraction (SAED). The electron diffraction pattern at measurement point 1 is shown in FIG. The electron diffraction pattern at measurement point 2 is shown in FIG. 9(b). The electron diffraction pattern at measurement point 3 is shown in FIG. 9(c). The electron diffraction pattern at measurement point 4 is shown in FIG. The electron diffraction pattern at measurement point 5 is shown in FIG. The electron diffraction pattern at measurement point 6 is shown in FIG. The electron diffraction pattern at measurement point 7 is shown in FIG. 9(d). The three numbers written above each spot in each electron diffraction pattern are the orientations (Miller indices) of the lattice planes corresponding to each spot.

[0100] The results of the above analyses using TEM and STEM showed that the hot-deformed magnets had the following characteristics: Crystal grains containing Nd and Cu were detected at each of the measurement points 1 to 3 and 7. That is, multiple crystal grains containing Nd and Cu were detected. For example, Nd 44.4 Cu 44。0 Fe 2.1 Co 9.5 The crystal grains are represented by the chemical formula Nd 43.7 Cu 44.3 Fe 2.8 Co 9.2 The crystal grains detected were expressed by the following chemical formula: The units of each number in these chemical formulas are atomic percent. NdO was detected at measurement point 4. Main phase particles were detected at measurement points 5 and 6, respectively. The Nd concentration (unit: atomic %) in each crystal grain containing Nd and Cu was higher than that in each main phase particle. Each grain containing Nd and Cu was in contact with one or more main phase particles. Each crystal grain containing Nd and Cu was cubic or orthorhombic. The space group indicating the symmetry of the crystal structure of each crystal grain containing Nd and Cu was Pnma. The electron diffraction patterns at measurement points 1 to 3 and 7, which originate from multiple crystal grains containing Nd and Cu, were compared with each other. The results of the comparison are as follows: The zone axes of several grains containing Nd and Cu ( <100> ) were oriented along one direction. That is, the zone axes ( <100> ) were nearly or completely parallel to each other. The zone axes of several grains containing Nd and Cu ( <100> The maximum angle between any pair of zone axes was 3°. The (010) planes of the multiple crystal grains containing Nd and Cu were oriented in the same direction, i.e., the (010) planes of the multiple crystal grains containing Nd and Cu were approximately or completely parallel to each other.

[0101] The area fractions AR of the cross sections of multiple crystal grains containing Nd and Cu were measured using backscattered electron images of the cross sections of the hot-worked magnet. Details of the method for measuring the area fraction AR were as described in the above embodiment. Phases located within the grain boundary phase, in contact with one or more main phase grains, containing Nd and Cu, and clearly distinguishable in contrast from the main phase grains and other grain boundary phases were considered to be crystal grains containing Nd and Cu. The vertical width (width in the direction of the easy axis C) of the backscattered electron image in which the area fraction AR was measured was 12.7 μm, and the horizontal width of the backscattered electron image in which the area fraction AR was measured was 9.5 μm. ImageJ, a public domain image processing software, was used to measure the area fraction AR. The area fraction AR (unit: %) of Example 1 is shown in Table 2 below. The electron diffraction patterns of each pair of crystal grains and the main phase grains that contact each other in the TEM image were measured. <001> and the main phase particles <001> The angle θ between The angle θ (unit: °) in Example 1 is shown in Table 2 below.

[0102] Five grain boundary phases containing one or more crystal grains containing Nd and Cu were randomly selected from a TEM image of the cross section of the hot-worked magnet. The width W of each grain boundary phase was measured in the TEM image, and the average value of the widths W of the five grain boundary phases was calculated. The width W of the grain boundary phase is the width of the grain boundary phase in the direction of the easy axis of magnetization C. The vertical width (width in the direction of the easy axis of magnetization C) of the backscattered electron image in which the width W of the grain boundary phase was measured was 2.54 μm, and the horizontal width of the backscattered electron image in which the width W of the grain boundary phase was measured was 1.90 μm. The average value (unit: nm) of the width W of the grain boundary phase in Example 1 is shown in Table 2 below.

[0103] The coercive force (HcJ), remanent magnetic flux density (Br), and squareness ratio (Hk / HcJ) of the hot-processed magnet of Example 1 were measured. The coercive force, remanent magnetic flux density, and squareness ratio were measured using a BH tracer. The coercive force was measured at 23°C, and the remanent magnetic flux density was measured at room temperature. The squareness ratio was measured at 23°C. The coercive force (unit: kA / m), remanent magnetic flux density (unit: T), and squareness ratio (unit: %) of Example 1 are shown in Table 2 below.

[0104] Various analyses and measurements were carried out on the hot-processed magnets of Examples 2 to 9 and Comparative Examples 1 to 3 using methods similar to those used in Example 1. The results of the various analyses and measurements for Examples 2 to 9 and Comparative Examples 1 to 3 are shown in Tables 2 and 3 below. In each of Examples 1, 5 to 7 and Comparative Example 1, crystal grain A was detected as one of a plurality of crystal grains in contact with one or more main phase grains. In Example 2, crystal grain B was detected as one of a plurality of crystal grains in contact with one or more main phase grains. In Example 3, crystal grain C was detected as one of a plurality of crystal grains in contact with one or more main phase particles. In Example 4, crystal grain D was detected as one of a plurality of crystal grains in contact with one or more main phase grains. In Comparative Example 2, crystal grain E was detected as one of a plurality of crystal grains in contact with one or more main phase particles. In Example 8, crystal grain F was detected as one of a plurality of crystal grains in contact with one or more main phase grains. In Comparative Example 3, crystal grain G was detected as one of a plurality of crystal grains in contact with one or more main phase particles. In Example 9, crystal grain H was detected as one of a plurality of crystal grains in contact with one or more main phase particles. The rare earth element R, transition metal element T, and element M contained in each of crystal grains A, B, C, D, E, F, G, and H are shown in Table 3 below. The contents (unit: mass %) of R, T and M in each of crystal grains A, B, C, D, E, F, G and H are shown in Table 3 below. The space groups indicating the symmetry of the crystal structure of each of the crystal grains A, B, C, D, E, F, G, and H are shown in Table 3 below. The crystal structures of the crystal grains A, B, C, D, E, F, G, and H are shown in Table 3 below. "fcc" in Table 3 below means a face-centered cubic lattice structure (cubic crystal). "tet" in Table 3 below means a tetragonal crystal. "bcc" in Table 3 below means a body-centered cubic lattice structure (cubic crystal). "ort" in Table 3 below means an orthorhombic crystal.

[0105] The "orientation" in the "Zone axis" column in Table 2 below refers to the zone axis ( <100> ) is 5° or less. In other words, "orientation" means that the angle between any pair of zone axes ( <100> ) means that it is oriented in one direction. The "non-oriented" in the "Zone axis" column in Table 2 below refers to the zone axis ( <100> ) the angle between any pair of zone axes is greater than 5°. In other words, "non-oriented" means that the zone axes ( <100> ) means that it is not oriented in one direction.

[0106] Except for the differences shown in Tables 2 and 3 below, the hot-processed magnets of Examples 2 to 9 each had the same characteristics as Example 1 described above.

[0107] The hot-deformed magnets of Comparative Examples 1 and 3 each contained a plurality of crystal grains containing Nd and Cu. However, in Comparative Examples 1 and 3, the zone axes ( <100> ) was not formed in one direction. Except for this, the hot-deformed magnets of Comparative Examples 1 and 3 had the same characteristics as Example 1 described above.

[0108] In the hot-processed magnet of Comparative Example 2, multiple crystal grains containing Nd and Cu were not detected. In Comparative Example 2, multiple amorphous phases containing Nd and Cu were detected in the grain boundary phase. Except for these points, the hot-processed magnet of Comparative Example 2 had the same characteristics as Example 1 described above. Only in Comparative Example 2, the average grain boundary phase width W refers to the average width of the grain boundary phase that does not contain crystal grains containing Nd and Cu. In other words, only in Comparative Example 2, the average grain boundary phase width W refers to the average width of the grain boundary phase that contains the amorphous phase containing Nd and Cu. Only in Comparative Example 2, the AR listed in Table 2 below refers to the area fraction of the cross section of multiple amorphous phases, not the area fraction of the cross section of multiple crystal grains. Since the Nd content in the raw material (alloy ribbon) of Comparative Example 2 is lower than that of Example 1, the volume fraction of the Nd-rich phase in the compact formed from the alloy ribbon is reduced, making it difficult for the grain boundary phase to liquefy during the hot plastic working process. Therefore, the formation of the grain boundary phase (liquid phase) during the hot plastic working process is insufficient, preventing proper orientation of the main phase particles. As a result, the remanence is reduced. Since the grain boundary phase of Comparative Example 2 is an oxide of the Nd-rich phase, the zone axes of the multiple crystal grains in the grain boundary phase cannot be aligned even if the magnet base material is cooled while maintaining the load (pressure p) during the unloading process after the hot plastic working process.

[0109] [Table 1]

[0110] [Table 2]

[0111] [Table 3] [Industrial Applicability]

[0112] For example, the RTB based hot-deformed magnet according to one aspect of the present disclosure may be used as a material for motors mounted on electric vehicles or hybrid vehicles. [Explanation of symbols]

[0113] 2...hot-deformed magnet, 2cs...cross section of hot-deformed magnet (cross section parallel to the easy axis of magnetization), 4...main phase particles, 6...grain boundary phase, 8...crystal grains (non-magnetic phase), C...direction of easy axis of magnetization, AB...direction perpendicular to the easy axis of magnetization, cza...zone axis, D...one direction in which the zone axis is oriented.< / uvw> < / uvw> < / uvw> < / uvw> < / uvw> < / uvw> < / uvw> < / uvw> < / uvw> < / uvw> < / uvw> < / uvw> < / uvw> < / uvw> < / uvw> < / uvw> < / uvw> < / uvw>

Claims

1. A hot-processed magnet comprising a rare earth element R, a transition metal element T, and boron, The hot-processed magnet contains Nd as the rare earth element R, The hot-processed magnet contains Fe as the transition metal element T, The hot-worked magnet includes a plurality of main phase grains and a grain boundary phase located between the plurality of main phase grains, the plurality of main phase particles contain the rare earth element R, the transition metal element T, and the boron; the grain boundary phase includes a plurality of crystal grains, a plurality of the crystal grains are in contact with one or more of the main phase grains, The zone axes of the plurality of crystal grains are oriented along one direction. Hot processed magnets.

2. the plurality of crystal grains are non-magnetic; The hot-worked magnet according to claim 1 .

3. an area fraction of the cross section of the plurality of crystal grains in the cross section of the hot-deformed magnet is 3% or more and 8% or less; the cross section of the hot-processed magnet is parallel to the easy axis of magnetization of the hot-processed magnet; The hot-worked magnet according to claim 1 .

4. the plurality of crystal grains contain the rare earth element R and the element M; the element M is at least one selected from the group consisting of Cu, Ga, Zn, Ni, and Cr; the content of the rare earth element R in the plurality of crystal grains is 50% by mass or more and 98% by mass or less, the content of the transition metal element T in the plurality of crystal grains is 0 mass% or more and 50 mass% or less, The content of the element M in the plurality of crystal grains is greater than 0 mass% and not more than 35 mass%. The hot-worked magnet according to claim 1 .

5. Each of the plurality of crystal grains is a cubic crystal, a tetragonal crystal, or an orthorhombic crystal; The zone axis is <100>, <010>, or <001>. The hot-worked magnet according to claim 1 .

6. the plurality of crystal grains contain Nd and Cu; Each of the plurality of crystal grains is a cubic crystal, a tetragonal crystal, or an orthorhombic crystal; The space group representing the symmetry of the crystal structure of the plurality of crystal grains is Pnma, I4 / mcm, Fm-3m, or Ia-3; The hot-worked magnet according to claim 1 .

7. the width of the grain boundary phase containing one or more of the crystal grains is 4 nm or more and 500 nm or less in the direction of the easy axis of magnetization of the hot-worked magnet; The hot-worked magnet according to claim 1 .

8. the one or more main phase particles in contact with the one or more crystal grains include at least one of columnar crystals and equiaxed crystals; The hot-worked magnet according to claim 1 .

9. The hot-processed magnet further contains an element M, the element M is at least one selected from the group consisting of Cu, Ga, Zn, Ni, and Cr; the content of the rare earth element R in the hot-processed magnet is 26.00% by mass or more and 32.00% by mass or less, the boron content in the hot-processed magnet is 0.77% by mass or more and 1.15% by mass or less, The content of the element M in the hot-processed magnet is 0.67% by mass or more and 7.30% by mass or less. The hot-worked magnet according to claim 1 .

10. The width of each of the plurality of main phase grains in the easy axis direction of magnetization of the hot-worked magnet is represented by S, a width of each of the plurality of main phase grains in a direction perpendicular to the easy axis direction is represented as L; The S is smaller than the L, L / S is 2 or more and 10 or less, The S is 20 nm or more and 200 nm or less. The hot-worked magnet according to claim 1 .

11. the angle between the <100> plane of the plurality of crystal grains and the <100> plane of one or more of the main phase particles is 0° or more and 10° or less; The hot-worked magnet according to claim 1 .

12. the angle between the <010> of the plurality of crystal grains and the <010> of one or more main phase particles is 0° or more and 10° or less; The hot-worked magnet according to claim 1 .

13. an angle between the <001> of the plurality of crystal grains and the <001> of one or more main phase grains is 0° or more and 10° or less; The hot-worked magnet according to claim 1 .

14. the one direction in which the zone axes of the plurality of crystal grains are oriented is parallel to the zone axes of one or more of the main phase particles that are in contact with the plurality of crystal grains; The hot-worked magnet according to claim 1 .

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