Thin ribbon, and method for producing hot-processed magnet

Abstract

To provide a thin ribbon that improves density of a compact formed from a thin ribbon.SOLUTION: A thin ribbon 4 contains an alloy comprising a rare earth element, iron, and boron. The thin ribbon 4 has a surface R and a surface F located on the opposite side of the surface R. The surface R includes an amorphous region 3 in which only an amorphous phase of the alloy is exposed. The surface F includes a crystalline region 7 in which at least a crystalline phase of the alloy is exposed. A plurality of recesses 9 are formed in the crystalline region 7. The surface R does not include the crystalline region 7 in which the plurality of recesses 9 are formed.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing a ribbon and a hot-worked magnet. [Background technology]

[0002] Generally, hot-worked magnets are manufactured from alloy ribbons. (See Patent Documents 1 and 2 below.) For example, alloy ribbons are produced by a rapid solidification method. In this method, a molten metal containing a rare earth element R, a transition metal element T, and boron (B) is rapidly cooled on the surface of a chill roll. As a result, the molten metal solidifies and becomes an alloy ribbon. The alloy ribbon is pulverized to obtain alloy powder. A compact is obtained by hot pressing the alloy powder. A hot-worked magnet is obtained by hot deforming the compact. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-135142 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-84802 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of one aspect of the present disclosure is to provide a ribbon that increases the density of a compact formed from the ribbon, and a method for producing a hot-worked magnet that uses the ribbon as a raw material. [Means for solving the problem]

[0005] For example, as described below, one aspect of the present disclosure relates to a ribbon according to any one of [1] to

[10] and a method for producing a hot-worked magnet according to

[11] .

[0006] [1] A ribbon containing an alloy containing a rare earth element, iron, and boron, the ribbon has a surface R and a surface F located on the back side of the surface R, the surface R includes an amorphous region in which only the amorphous phase of the alloy is exposed, the surface F includes at least a crystalline region in which a crystalline phase of the alloy is exposed, a plurality of recesses are formed in the crystalline region; the surface R does not include the crystalline region in which the plurality of recesses are formed; Thin ribbon.

[0007] [2] The surface F further includes, in addition to the crystalline region, a region where the amorphous phase is exposed. [1] The thin ribbon described in [1].

[0008] [3] The amorphous phase is exposed in at least one of the plurality of recesses. [1] or [2].

[0009] [4] The amorphous phase is exposed in at least one of the recesses, the area ratio of the crystalline phase in the crystalline region is 0.18 or more and 0.90 or less; The ribbon according to any one of [1] to [3].

[0010] [5] The amorphous phase is exposed in at least one of the recesses, The perimeter of one of the recesses as observed from a direction perpendicular to the surface F is represented as L, The area of ​​one of the recesses as viewed from a direction perpendicular to the surface F is represented as A, L 2 / A is between 100 and 400, The ribbon according to any one of [1] to [4].

[0011] [6] The crystalline phase is exposed in all of the plurality of recesses. [1] or [2].

[0012] [7] The amorphous region includes a plurality of concave curved surfaces. The ribbon according to any one of [1] to [6].

[0013] [8] Used as a raw material for hot-worked magnets. The ribbon according to any one of [1] to [7].

[0014] [9] The thickness of the ribbon is 10 μm or more and 60 μm or less. The ribbon according to any one of [1] to [8].

[0015]

[10] The volume of the crystalline phase contained in the ribbon is V C is expressed as The volume of the amorphous phase contained in the ribbon is V A is expressed as V C / (V C +V A ) is greater than 0 and less than or equal to 0.40, The ribbon according to claim 1.

[11] A step of pulverizing the ribbon according to any one of [1] to

[10] to obtain an alloy powder; a step of obtaining a compact by pressing the alloy powder while heating; obtaining a magnet substrate by hot plastic working of the compact; Including, Manufacturing method of hot-deformed magnets. [Effects of the Invention]

[0016] According to one aspect of the present disclosure, there are provided a ribbon that increases the density of a compact formed from the ribbon, and a method for producing a hot-worked magnet that uses the ribbon as a raw material. [Brief explanation of the drawings]

[0017] [Figure 1](a) in FIG. 1 is a schematic perspective view of one specific example of a ribbon, and (b) in FIG. 1 is a schematic cross-sectional view of the ribbon of (a) in FIG. 1, where the cross-section of (b) in FIG. 1 is parallel to the thickness direction Z (YZ plane) of the ribbon. [Figure 2] FIG. 2 is an enlarged view of a part (region II) of the cross section of (b) in FIG. [Figure 3] (a) in Figure 3 is a backscattered electron image of a surface F of a specific example of the ribbon, and (b) in Figure 3 is a backscattered electron image of a surface R of a specific example of the ribbon. The two backscattered electron images shown in (a) in Figure 3 and (b) in Figure 3 are images taken at the same magnification. [Figure 4] (a) in Figure 4 is a backscattered electron image of a crystalline region (part of surface F) of one specific example of the ribbon, and (b) in Figure 4 is a backscattered electron image of an amorphous region (part of surface R) of one specific example of the ribbon. The two backscattered electron images shown in (a) in Figure 4 and (b) in Figure 4 are images taken at the same magnification and at a higher magnification than the two backscattered electron images shown in (a) in Figure 3 and (b) in Figure 3. [Figure 5] (a) in Figure 5 is a backscattered electron image of a crystalline region (part of surface F) of one specific example of the ribbon, and (b) in Figure 5 is a backscattered electron image of an amorphous region (part of surface R) of one specific example of the ribbon. The two backscattered electron images shown in (a) in Figure 5 and (b) in Figure 5 are images taken at the same magnification and at a higher magnification than the two backscattered electron images shown in (a) in Figure 4 and (b) in Figure 4. [Figure 6] FIG. 6 is an enlarged view of a portion of the backscattered electron image (crystalline region) shown in (a) of FIG. [Figure 7] (a) in Figure 7 is a schematic perspective view of a hot-processed magnet produced from a thin ribbon, (b) in Figure 7 is a schematic diagram of a cross section of the hot-processed magnet of (a) in Figure 7 (a view taken along the arrows in the direction of line b-b in the hot-processed magnet), the cross section of (b) in Figure 7 is parallel to the direction C of the easy axis of magnetization of the hot-processed magnet, and (c) in Figure 7 is an enlarged view of a portion (region VII) of the cross section of (b) in Figure 7. [Figure 8]FIG. 8 is a schematic diagram (cross-sectional view) showing a method for producing a ribbon (a super-rapid solidification method described later). DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, embodiments of the present disclosure will be described 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. X, Y, and Z shown in each drawing represent three mutually orthogonal coordinate axes. The directions of the X-axis, Y-axis, and Z-axis are common to all drawings.

[0019] The ribbon according to the present disclosure may be used as a raw material for a hot-processed magnet. In the present disclosure, the alloy powder refers to a pulverized ribbon. That is, the alloy powder and the individual alloy particles that make up the alloy powder are substantially the same as the ribbon, except that they have been subjected to a pulverization process.

[0020] (Composition of ribbon) The ribbon contains an alloy. The alloy contained in the ribbon contains a rare earth element R, a transition metal element T, and boron (B). The ribbon may consist only of the alloy. The ribbon may further contain trace amounts of other components (for example, elemental metals or unavoidable impurities) in addition to the alloy.

[0021] The alloy contained in the ribbon contains at least neodymium (Nd) as the rare earth element R. The alloy may further contain another rare earth element R in addition to Nd. The other rare earth element R contained in the alloy 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 alloy does not necessarily contain a heavy rare earth element (e.g., both Dy and Tb).

[0022] The alloy contained in the ribbon contains at least iron (Fe) as the transition metal element T. The alloy may contain only Fe as the transition metal element T. The alloy may contain both Fe and cobalt (Co) as the transition metal element T.

[0023] The alloy composition contained in the ribbon is R2T 14 It may be expressed as B. R2T 14 B is a ternary intermetallic compound with hard magnetic properties. 14 B is (Nd 1-x Pr x )2(Fe 1-y Co y ) 14 B. x may be greater than or equal to 0 and less than 1. y may be greater than or equal to 0 and less than 1. R2T 14 B may contain heavy rare earth elements such as Tb and Dy as the rare earth element R in addition to light rare earth elements. 14 B may contain other elements in addition to R, T, and B. For example, R2T 14 A part of B in B may be substituted with another element such as carbon (C).

[0024] The content of the rare earth element R in the alloy contained in the ribbon may be 26.00 mass% or more and 33.00 mass% or less. The total proportion of Nd and Pr in all the rare earth elements R may be 80 atomic% or more and 100 atomic% or less. The total content of Tb and Dy in the alloy may be 0.00 mass% or more and 5.00 mass% or less. Tb and Dy are not essential elements for the alloy contained in the ribbon.

[0025] The B content in the alloy contained in the ribbon may be 0.75 mass % or more and 1.20 mass % or less.

[0026] The alloy contained in the ribbon may contain gallium (Ga). The Ga content in the alloy may be 0.03 mass % or more and 1.00 mass % or less. Ga is not an essential element for the alloy contained in the ribbon. The alloy contained in the ribbon may contain aluminum (Al). The content of Al in the alloy may be 0.01 mass % or more and 0.2 mass % or less. Al is not an essential element for the alloy contained in the ribbon. The alloy contained in the ribbon may contain copper (Cu). The Cu content in the alloy may be 0.01 mass % or more and 1.50 mass % or less. Cu is not an essential element for the alloy contained in the ribbon. The alloy contained in the ribbon may contain cobalt (Co). The content of Co in the alloy may be 0.30 mass % or more and 6.00 mass % or less. Co is not an essential element for the alloy contained in the ribbon.

[0027] The remainder of the alloy contained in the ribbon, excluding the above elements, may be Fe alone, or Fe and other elements. The total content of the elements other than Fe in the remainder may be 5 mass% or less with respect to the total mass of the alloy. For example, the alloy contained in the ribbon may contain, as other elements (e.g., inevitable impurities), at least one element selected from the group consisting of silicon (Si), titanium (Ti), Mn (manganese), Zr (zirconium), vanadium (V), chromium (Cr), nickel (Ni), 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). The total content of the other elements in the alloy may be 0.001 mass% or more and 0.50 mass% or less.

[0028] The composition of the ribbon may be analyzed by, for example, X-ray fluorescence (XRF) analysis, inductively coupled plasma (ICP) emission analysis, inert gas fusion-non-dispersive infrared (NDIR) analysis, oxygen flow combustion-infrared absorption analysis, inert gas fusion-thermal conductivity analysis, etc.

[0029] (Structure, crystalline and amorphous of ribbons) As shown in (a) of FIG. 1 and (b) of FIG. 1, the ribbon 4 has a surface R and a surface F located on the reverse side of the surface R. As shown in Figure 2, the surface R includes an amorphous region 3 where only the amorphous phase of the alloy is exposed. That is, at least a portion of the surface R is the amorphous region 3. The entire surface R may be the amorphous region 3. That is, only the amorphous phase of the alloy may be exposed over the entire surface R. On the other hand, surface F includes a crystalline region 7 in which at least the crystalline phase of the alloy is exposed. In other words, at least a portion of surface F is the crystalline region 7. The entire surface F may be the crystalline region 7. A plurality of recesses 9 (dents) are formed in the crystalline region 7. The amorphous phase of the alloy may be exposed in the portion of surface F other than the crystalline region. Surface R does not include a crystalline region 7 in which a plurality of recesses 9 are formed. Therefore, surfaces R and F can be distinguished based on the presence or absence of a crystalline region 7 in which a plurality of recesses 9 are formed. The amorphous region 3 in surface R may be located behind the crystalline region 7 in surface F. Note that the feature that "surface R does not include a crystalline region 7 in which a plurality of recesses 9 are formed" means that the crystalline region 7 in which a plurality of recesses 9 are formed is not substantially observed on surface R. For example, the amorphous nature of the amorphous region 3 and the crystallinity of the crystalline region 7 may be confirmed by one or more analytical methods selected from the group consisting of thin film X-ray diffraction, transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), and scanning electron microscopy (SEM).

[0030] The crystalline phase of the alloy is R2T 14 B single crystal or R2T 14 The crystalline phase of the alloy may include polycrystalline B. 14 It may consist of only crystals of B. 14 The crystal of B may be tetragonal. For example, R2T 14 The crystal axes (principal translation vectors) of B may be 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 14The 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. In other words, the R2T included in the hot-processed magnet produced from the ribbon 4 14 The (001) plane of the tetragonal crystal of B may be approximately or completely perpendicular to the direction of the easy axis of magnetization C of the hot-processed magnet.

[0031] In the hot forming process described below, a formed body is formed by heating and pressurizing the pulverized ribbons 4. In the early stage of the hot forming process, the pressure acting on the ribbons 4 is relatively low, and each of the ribbons 4 is therefore likely to move. Therefore, in the early stage of the hot forming process, as the ribbons 4 are pressed, each of the ribbons 4 rotates and moves, and the gaps between the ribbons 4 decrease. However, the greater the frictional force acting between the plurality of ribbons 4, the more the rotation and movement of the plurality of ribbons 4 are hindered, making it difficult to reduce the gaps between the plurality of ribbons 4, and reducing the density of the compact. The frictional force acting between the plurality of ribbons 4 increases due to the close contact between the plurality of ribbons 4. In other words, the frictional force acting between the plurality of ribbons 4 increases as the contact area between the plurality of ribbons 4 increases. The amorphous regions 3 contained in the surface R of each of the plurality of ribbons 4 easily soften or liquefy with an increase in temperature, lubricating the plurality of ribbons 4. As a result, the frictional force acting between the plurality of ribbons 4 is reduced, the rotation and movement of the plurality of ribbons 4 is promoted, the gaps between the plurality of ribbons 4 are reduced, and the density of the compact is increased. In particular, when the surface R of each of the plurality of ribbons 4 is in contact with one another, the frictional force acting between the plurality of ribbons 4 is likely to be reduced. As the density of the compact increases, the remanence of the hot-worked magnet formed from the compact also increases. In contrast to the amorphous regions 3, the crystalline regions 7 included in the surface F of each of the plurality of ribbons 4 are unlikely to soften or liquefy with increasing temperature. Therefore, the crystalline regions 7 are unlikely to contribute to the lubrication of the plurality of ribbons 4. In particular, when the surfaces F of the plurality of ribbons 4 come into contact with each other, frictional forces tend to act between the plurality of ribbons 4, which tends to inhibit the rotation and movement of the plurality of ribbons 4. However, the plurality of recesses 9 formed in the crystalline regions 7 create gaps between the plurality of ribbons 4 and inhibit the adhesion of the plurality of ribbons 4 to each other. In other words, the plurality of recesses 9 formed in the crystalline regions 7 reduce the substantial contact area between the plurality of ribbons 4. Even if the surfaces F of the plurality of ribbons 4 come into contact with each other, the plurality of recesses 9 formed in the crystalline regions 7 can inhibit the adhesion of the plurality of ribbons 4 to each other. Therefore, the plurality of recesses 9 formed in the crystalline regions 7 reduce the frictional forces acting between the plurality of ribbons 4, making it difficult for the frictional forces to inhibit the rotation and movement of the plurality of ribbons 4. As a result, the gaps between the plurality of thin ribbons 4 decrease, the density of the compact increases, and the residual magnetic flux density of the hot-worked magnet formed from the compact also increases. At the end of the hot forming process, when the pressure acting on the multiple thin ribbons 4 is relatively high, the multiple thin ribbons 4 are compressed and arranged in the forming body so that the gaps between the multiple thin ribbons 4 are almost or completely eliminated.

[0032] Surface F may further include regions where the amorphous phase is exposed, in addition to the crystalline regions 7 where the multiple recesses 9 are formed. When surface F further includes regions where the amorphous phase is exposed, the amorphous phase in surface F gradually crystallizes during the hot-forming step while being gently incorporated into the crystalline regions 7. This suppresses rapid crystal growth of the alloy, making it difficult for coarse crystal grains of the alloy to form, and improves the coercive force of the hot-worked magnet produced from the multiple ribbons 4. In conventional hot-forming processes, the lower the temperature of the multiple ribbons, the less likely the ribbons are to soften and liquefy, making it difficult for the compact to become dense. In contrast, according to this embodiment, even when the hot-forming temperature is low enough to suppress the formation of coarse crystal grains, the compact becomes dense and its density increases due to the mechanism described above. As a result, the remanence of the hot-processed magnet formed from the compact also increases. In other words, according to this embodiment, the formation of coarse crystal grains during the hot-processing process is suppressed without sacrificing the remanence of the hot-processed magnet, making it easier to obtain a high coercive force for the hot-processed magnet.

[0033] The amorphous phase may be exposed in at least one of the recesses 9 formed in the crystalline region 7. The amorphous phase may also be exposed in all of the recesses 9. The gaps resulting from the recesses 9 remaining in the compact after the hot-forming process may actually contribute to a decrease in the density of the compact. However, if the amorphous phase is exposed in at least one of the recesses 9, the amorphous phase in each recess 9 softens or liquefies and deforms or moves as the temperature rises during the hot-forming process. As a result, the amorphous phase fills each recess 9, and gaps resulting from each recess 9 are less likely to remain in the compact, improving the density of the compact. When an amorphous phase is exposed in at least one or all of the recesses 9, the area ratio of the crystalline phase in the crystalline region 7 may be 0.18 to 0.90, or 0.180 to 0.757. The area ratio of the crystalline phase in the crystalline region 7 may be rephrased as the area ratio of the portion of the crystalline region 7 excluding the recesses 9. When the area ratio of the crystalline phase is within the above range, the area ratio (and volume ratio) of the crystalline phase and amorphous phase exposed in the crystalline region 7 is easily adjusted appropriately, and the above-mentioned effects resulting from the crystalline phase and amorphous phase being mixed in the crystalline region 7 are easily obtained. For the same reason, the area ratio of the crystalline phase in the entire surface F may also be 0.18 to 0.90, or 0.180 to 0.757.

[0034] FIG. 4(a) is a backscattered electron image of the crystalline region 7 taken by SEM, showing the crystalline region 7 enlarged 1000 times. FIG. 5(a) is also a backscattered electron image of the crystalline region 7 taken by SEM, showing the crystalline region 7 enlarged 10,000 times. In the flat portion of the crystalline region 7, excluding the recesses 9, the crystalline phase of the alloy is exposed. For example, as shown in FIG. 5(a), in the flat portion of the crystalline region 7, excluding the recesses 9, a fine structure (crystal grains of the alloy) with a width of approximately less than 1 μm is present. On the other hand, no fine structure is observed within each recess 9. Furthermore, each recess 9 in the crystalline region 7 can be distinguished from other portions (the crystalline phase exposed in the flat portion) based on the contrast. In other words, each recess 9 in the crystalline region 7 can be distinguished from other portions based on the presence or absence of a fine structure (crystal grains) and the contrast in the backscattered electron image. The area ratio of the crystalline phase in the crystalline region 7 may be measured in a backscattered electron image of the crystalline region 7 magnified 1000 times. To measure the area ratio of the crystalline phase in the crystalline region 7, threshold processing (binarization processing) of the backscattered electron image based on the RGB color model (Red-Green-Blue color model) is performed. By the binarization processing, a monochrome image is obtained from the backscattered electron image. Based on the contrast in the monochrome image, each recess 9 in the crystalline region 7 is distinguished from other portions, and the area (opening area) of each recess 9 is measured. For example, as shown in FIG. 6, the outline 9a of each recess 9 in the crystalline region 7 is identified, and each recess 9 is distinguished from other portions based on the outline 9a. The total area A of the crystalline region 7 (monochrome image) WHOLE The area A of the crystalline phase in the crystalline region 7 is calculated by subtracting the sum of the areas of all the recesses 9 in the crystalline region 7 from the area A of the crystalline phase in the crystalline region 7. C The area ratio of the crystalline phase in the crystalline region 7 (unit: no) can be considered as A C / A WHOLE The area of ​​the crystalline phase, A, can be expressed as Cmeans the area of ​​the crystalline phase observed from a direction perpendicular to the surface F. The area of ​​each recess 9 also means the area of ​​each recess 9 observed from a direction perpendicular to the surface F. Image processing software (for example, ImageJ, which is public domain image processing software) may be used for the above image processing and measurement of each area.

[0035] The perimeter of one recess 9 observed from a direction perpendicular to the surface F is represented as L. As shown in FIG. 6, the perimeter of one recess 9 means the total length of the contour line 9a of one recess 9. The area of ​​one recess 9 observed from a direction perpendicular to the surface F is represented as A. When an amorphous phase is exposed in at least one or all of the recesses 9, L 2 / A may be 100 or more and 400 or less, or 143 or more and 156 or less. L 2 When / A is within the above range, many areas where the crystalline phase and the amorphous phase come into contact are likely to exist in the crystalline region 7, and the above-mentioned effects resulting from the mixture of the crystalline phase and the amorphous phase within the crystalline region 7 are likely to be obtained. The perimeter L of one recess 9 may be measured on the surface of the crystalline region 7 magnified 1000 times (for example, (a) in FIG. 4 or the backscattered electron image in FIG. 6), similar to the area ratio of the crystalline phase. The perimeter L of one recess 9 may be measured on the backscattered electron image that has been subjected to binarization processing, similar to the area ratio of the crystalline phase. The volume of the crystalline phase contained in the ribbon 4 is V C The volume of the amorphous phase contained in the ribbon can be expressed as V A It can be expressed as: V C / (V C +V A ) may be greater than 0 and less than or equal to 0.40, or greater than or equal to 0.02 and less than or equal to 0.38. A part of the interior of the ribbon 4 before pulverization is exposed as a part of the surface of the alloy powder obtained by pulverizing the ribbon 4. C / (V C +V A) is within the above range, the volume ratio of the crystalline phase to the amorphous phase inside the ribbon 4 is appropriately adjusted, and therefore the area ratio (and volume ratio) of the crystalline phase to the amorphous phase in the portion of the surface of the alloy powder that originates from the inside of the ribbon 4 before pulverization is also likely to be appropriately adjusted. If the area ratio (and volume ratio) of the crystalline phase to the amorphous phase on the surface of the alloy powder is appropriately adjusted during the hot compaction step, the above-mentioned effects resulting from the crystalline phase and the amorphous phase being mixed in the crystalline region 7 are likely to be obtained. From the X-ray diffraction spectrum of either the ribbon 4 or the alloy powder obtained by pulverizing the ribbon 4, V C and V A As standard samples to be compared with the X-ray diffraction spectrum of the ribbon 4 or the alloy powder, an X-ray diffraction spectrum of a ribbon consisting only of a crystalline phase (spectrum C) and an X-ray diffraction spectrum of a ribbon consisting only of an amorphous phase (spectrum A) may be measured. By a scale analysis based on spectrum C and spectrum A, V C and V A For the scale analysis, analysis software for X-ray diffraction spectra (for example, HighScore Plus manufactured by Malvern Panalytical Ltd.) may be used. TM ) may be used. Prior to scale analysis, a background may be subtracted from each X-ray diffraction spectrum.

[0036] The crystalline phase may be exposed in all of the recesses 9. In other words, the surface of each of the recesses 9 formed in the crystalline region 7 may be a crystalline phase. In areas on the surface of the ribbon 4 where the amorphous phase aggregates and there is no crystalline phase nearby, coarse crystal grains of the alloy are likely to be formed due to rapid crystallization of the alloy during the hot forming process. Coarse crystal grains reduce the coercive force of the hot-worked magnet. However, when the crystalline phase is exposed in all of the recesses 9, rapid crystallization of the alloy is suppressed in the crystalline region 7 including the recesses 9, making it difficult for coarse crystal grains to form, and reducing the coercive force. For the same reason, only the crystalline phase may be exposed over the entire surface F (including the recesses 9). As described above, according to this embodiment, even when the hot forming temperature is low enough to suppress the formation of coarse crystal grains, the formation of coarse crystal grains during the hot forming process is suppressed without sacrificing the remanence of the hot-processed magnet, making it easier to obtain a high coercive force for the hot-processed magnet.

[0037] A part or the whole of the surface R or the amorphous region 3 may be flat. As shown in FIG. 2 , the surface R or the amorphous region 3 may include a plurality of concave (smooth) curved surfaces 5. That is, a part of the surface R or the amorphous region 3 may be a concave curved surface 5. Similar to the plurality of recesses 9 formed in the crystalline region 7, the plurality of concave curved surfaces 5 formed in the surface R or the amorphous region 3 become gaps between the plurality of ribbons 4 and suppress adhesion between the plurality of ribbons 4. In other words, similar to the plurality of recesses 9 formed in the crystalline region 7, the plurality of concave curved surfaces 5 contribute to increasing the density of the compact in the early stage of the hot forming process. Figure 3(b) is a backscattered electron image of surface R (surface R including amorphous regions 3) taken by SEM, showing surface R magnified 150 times. In Figure 3(b), multiple concave curved surfaces 5 (areas that are darker than the surrounding area) can be observed. Figure 4(b) is a backscattered electron image of the amorphous region 3 (part of the surface R) photographed by SEM, showing the amorphous region 3 magnified 1000 times. In Figure 4(b), multiple concave curved surfaces 5 can also be observed.

[0038] For example, the thickness of the ribbon 4 may be 10 μm or more and 60 μm or less. For example, the length of the ribbon 4 may be about several centimeters. For example, the width of the ribbon 4 may be 0.5 mm or more and 5.0 mm or less. For example, the maximum width of each recess 9 formed in the crystalline region 7 may be 3 μm or more and 20 μm or less. In other words, the maximum width of one recess observed from a direction perpendicular to the surface F may be 3 μm or more and 20 μm or less. For example, the depth of each recess 9 formed in the crystalline region 7 may be 0.1 μm or more and 1.0 μm or less.

[0039] (hot-processed magnets) The compact obtained by the hot compacting process becomes a hot-worked magnet by undergoing a hot plastic processing process. Figure 7(a) is a perspective view of the hot-worked magnet 2. Figure 7(b) is a schematic diagram of a cross section 2cs of the hot-worked magnet 2. Figure 7(c) is an enlarged view of a portion (region VII) of the cross section of Figure 7(b). The cross section 2cs of the hot-worked magnet 2 is approximately or completely parallel to the easy axis C of the hot-worked magnet 2. The easy axis C is parallel to the line connecting the pair of magnetic poles of the hot-worked magnet 2. In other words, the easy axis C is the direction from the south pole of the hot-worked magnet 2 to the north pole of the hot-worked magnet 2. The AB direction is perpendicular to the easy axis C. As shown in Figure 7(c), the hot-worked magnet 2 contains multiple main phase particles 4A. The multiple main phase particles 4A observed in the cross section 2cs parallel to the easy axis C are flat. The flat main phase grains 4A are derived from the above-described thin ribbons 4. The flat main phase grains 4A are stacked along the direction C of the easy axis of magnetization.

[0040] 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.

[0041] (Methods for manufacturing ribbons and hot-processed magnets) The method for producing a hot-worked magnet according to this embodiment includes at least a ribbon production step, a pulverization / classification step, a hot pressing step, and a hot deforming step. The method for producing a hot-worked magnet may further include other steps such as a grain boundary diffusion step. However, the grain boundary diffusion step is not essential.

[0042] 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.

[0043] The ribbon production process is a process in which a large number of ribbons 4 are produced from multiple types of raw metals by the rapid solidification method. An overview of the rapid solidification method is shown in FIG. 8. In the rapid solidification method, molten metal 4B in a container 83 is sprayed onto the surface of a chill roll 81 from a nozzle located at the tip of the container 83. The molten metal 4B contacts the surface of the chill roll 81. Upon contact with the surface of the chill roll 81, the molten metal 4B is rapidly cooled and solidified, becoming a long, thin ribbon (i.e., the ribbon 4). The portion of the molten metal 4B that contacts the surface of the chill roll 81 becomes surface R of the ribbon 4, and the portion of the molten metal 4B that does not contact the surface of the chill roll 81 becomes surface F of the ribbon 4. The ribbon 4 formed on the surface of the chill roll 81 is instantly ejected by the chill roll 81, which is rotating at high speed. A container for the ribbon 4 is placed in the direction in which the ribbon 4 is ejected, and the ribbon 4 is collected into the container. A large number of ribbons 4 are produced by the above method.

[0044] The container 83 containing the molten metal 4B and the cooling roll 81 are placed in a chamber 85. That is, the ribbon 4 is produced in the chamber 85. During the implementation of the rapid solidification method, Ar gas is continuously supplied into the chamber 85 at a predetermined wind speed. During the implementation of the rapid solidification method, the pressure P IN The pressure P in the chamber 85 is maintained at a predetermined value. IN and atmospheric pressure P ATM The difference is ΔP(=P IN -P ATM) For example, ΔP may be 0.0 kPa or more and 1.5 kPa. The lower ΔP is, the more likely the crystalline phase is exposed in each recess 9 formed in the crystalline region 7. The higher ΔP is, the more likely the amorphous phase is exposed in each recess 9 formed in the crystalline region 7. For example, the wind speed of the Ar gas supplied into the chamber 85 may be 9 m / s or more and 49 m / s or less. When the wind speed of the Ar gas is zero m / s, multiple recesses 9 tend not to be formed in the crystalline region 7. When the wind speed of the Ar gas is greater than zero m / s and less than 9 m / s, the amorphous region 3 is less likely to be formed on the surface R, and only the crystalline phase of the alloy tends to be exposed throughout the entire surface R.

[0045] The molten metal is a metal (plurality of raw material metals) containing multiple elements that will constitute the hot-processed magnet. For example, the multiple raw material metals may include rare earth elements or other elements (elemental metals), alloys containing rare earth elements or other elements, pure iron, or ferroboron. The multiple raw material metals are weighed to match the composition of the desired hot-processed magnet.

[0046] The molten metal may be obtained by heating a plurality of raw metals in a vessel by high-frequency induction heating. For example, the temperature of the molten metal sprayed from the nozzle (spray temperature) may be 1200°C or higher and 1400°C or lower. For example, the rate of temperature increase until the temperature of the plurality of raw metals reaches the spray temperature may be about 20 to 100°C / second.

[0047] 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 0.1° C. / sec. The higher the cooling rate, the more the crystals (R2T 14B) particle diameter tends to become finer, and the coercive force of the hot-processed magnet tends to increase. 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 ribbon 4. 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 ribbon 4. The thickness of the main phase particles 4A in the direction of the easy axis of magnetization (the length of the minor axis of the main phase particles 4A) depends on the thickness of the ribbon 4 (as well as the pulverization and classification of the ribbon 4). The thinner the ribbon 4, the smaller the thickness (particle diameter) of the main phase particles 4A, and the coercive force of the hot-processed magnet tends to increase.

[0048] After the ribbon preparation step, a pulverization / classification step may be performed. The pulverization / classification step is a step in which the ribbon 4 is pulverized to obtain an alloy powder. For example, the pulverization / classification step may be a step in which the ribbon 4 is pulverized using a pulverizer to produce a coarse powder, and the coarse powder is classified to recover an alloy powder having a predetermined particle size and aspect ratio. The alloy powder is a precursor of the main phase particles 4A contained in the hot-worked magnet. The shape of each alloy particle constituting the alloy powder may be plate-like or flake-like. For example, the ribbon 4 may be pulverized using at least one of a cutter mill and a propeller mill. 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 or more and 2800 μm or less.

[0049] The hot compacting step is a step of obtaining a compact by heating and pressing the ribbon 4 (alloy powder). 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 particles, resulting in a dense compact. Heating the alloy powder during pressurization also forms a liquid phase (an R-rich phase, such as an Nd-rich phase) on the surface of the alloy powder, filling the voids (grain boundaries) between the alloy powder particles. The liquid phase lubricates the alloy powder, making it easier to compress the alloy powder and more likely to obtain 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 pressed at room temperature to form a compact. The compact obtained by the cold compacting step may be densified by heating and pressing it 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.

[0050] After the hot compaction step, a hot plastic working step is carried out. The hot plastic working step is a step of obtaining a magnet base material by hot plastic working the compact obtained by the hot compaction step. For example, in the hot plastic working step, the compact is heated and pressurized to form a plurality of main phase grains 4A (R2T 14 A magnet base material containing B crystal grains is obtained. For example, die upset forging may be performed as the hot plastic working process. For example, hot extrusion may be performed as the hot plastic working process.

[0051] Heating during the hot plastic working process liquefies the grain boundary phase in the compact, generating a liquid phase (R-rich phase). Pressure during the hot plastic working process applies stress to the compact in a predetermined direction, distorting each alloy particle (ribbon 4) that makes up the compact. The generation of the liquid phase and the distortion of the alloy particles cause anisotropic growth of the crystal grains in a direction perpendicular to their c-axes. The liquid phase also lubricates each crystal grain, and a force acts 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 particle 4A) become oriented parallel to the stress direction. In other words, multiple flat main phase particles 4A extending in a direction perpendicular to the c-axis are stacked along the stress direction. The easy axis of magnetization of the magnet substrate becomes approximately or completely parallel to the stress direction.

[0052] 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 particles 4A is likely to be less than 20 nm, and the c-axes of the main phase particles 4A (crystal grains) are unlikely to be oriented 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 4A (crystal grains) will proceed abnormally, and coarse main phase particles 4A will likely be formed, with the average length of the minor axis of the main phase particles 4A likely to exceed 200 nm. The coarse main phase particles 4A will be difficult to orient in the direction of the easy axis of magnetization. For example, the pressure applied to the compact in the hot plastic working step (hot plastic working pressure) may be 50 MPa or more and 200 MPa or less. For example, the time during which the hot plastic working temperature and hot plastic working pressure are maintained within the above ranges (hot plastic working time) may be several tens of seconds.

[0053] 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.

[0054] After the hot plastic working process, the following grain boundary diffusion process may be carried out. The grain boundary diffusion process is a process in which a diffusion material containing a heavy rare earth element is attached to the surface of the magnet substrate, and the diffusion material and magnet substrate are heated. By heating the magnet substrate to which the diffusion material is attached, 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 4A. Near the surface of the main phase particles 4A, some of the light rare earth elements (such as Nd) are substituted with the heavy rare earth element. By localizing the heavy rare earth element near the surface and at the grain boundaries of the main phase particles 4A, the anisotropy magnetic 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.

[0055] 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.

[0056] 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 further contain a metal other than a rare earth element, such as Cu or Al, in addition to the heavy rare earth element and the light rare earth element. For example, the diffusing material may be 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.

[0057] 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.

[0058] 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.

[0059] 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 technical scope of the present disclosure. [Example]

[0060] 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.

[0061] Example 1 Each step in Example 1 below was carried out in a non-oxidizing atmosphere (Ar gas).

[0062] In the ribbon production process, a plurality of ribbons were produced from a molten metal containing a plurality of raw metals by the above-mentioned rapid solidification method shown in Figure 8. The molten metal was maintained at approximately 1200°C. The surface temperature of the chill roll was maintained at approximately room temperature. The above-mentioned ΔP was maintained at the value shown in Table 1 below. The wind velocity V of the Ar gas supplied into the chamber was Ar was maintained at the values ​​shown in Table 1 below. The melt contained Nd, Pr, Fe, B, Ga, and Co. The Nd content in the molten metal was 30.17 mass %. The Pr content in the molten metal was 0.13 mass %. The Fe content in the molten metal was 64.25 mass %. The B content in the molten metal was 0.90 mass %. The Ga content in the molten metal was 0.59 mass %. The Co content in the molten metal was 3.96 mass %.

[0063] A plurality of backscattered electron images were taken by SEM of each of a pair of surfaces of the ribbon of Example 1. From the backscattered electron images, the following plurality of characteristics of the ribbon of Example 1 were identified.

[0064] The ribbon had a surface R and a surface F located on the reverse side of the surface R. The surface R included an amorphous region 3 in which only the amorphous phase of the alloy was exposed. The surface F included at least a crystalline region 7 in which the crystalline phase of the alloy was exposed. A plurality of recesses 9 were formed in the crystalline region 7 . In each of the plurality of recesses 9, the amorphous phase was exposed. The surface R did not include the crystalline region 7 in which the plurality of recesses 9 were formed.

[0065] A plurality of backscattered electron images of the surface F of the ribbon of Example 1 are shown in FIG. 3(a), FIG. 4(a), FIG. 5(a), and FIG. A plurality of backscattered electron images of the surface R of the ribbon of Example 1 are shown in FIG. 3(b), FIG. 4(b), and FIG. 5(b). Surface R (backscattered electron image in Figure 3(b)) magnified 150 times contained multiple concave curved surfaces. The area ratio A of the crystalline phase in the crystalline region 7 (backscattered electron image (a) in Figure 4) magnified 1000 times C / A WHOLE was measured. In the crystalline region 7 (backscattered electron image in Figure 4(a)) magnified 1000 times, L 2 / A was measured. As in the above embodiment, A C / A WHOLE and L 2In each measurement, backscattered electron images were binarized using image processing software (ImageJ). By the method according to the above embodiment, V C / (V C +V A ) was measured. Example 1A C / A WHOLE , L 2 / A, and V C / (V C +V A ) are shown in Table 2 below. However, L in Example 1 2 The L / A of Example 1 shown in Table 2 below was measured in five recesses 9. 2 / A is the average value of the five measurements.

[0066] The alloy powder was produced by pulverizing the multiple ribbons. In the hot compacting process, the alloy powder was compressed in a die while being heated in the die, to produce a compact (i.e., a hot-processed magnet). The compact was a rectangular parallelepiped. The dimensions of the compact were 22 mm x 11 mm x 30 mm. The hot compacting temperature T (unit: °C) was as shown in Table 1 below. The hot compacting pressure was 150 MPa. The hot compacting time was 240 seconds.

[0067] The compact of Example 1 was produced by the above method. The bulk density (unit: g / cc) of the compact was measured five times by the Archimedes method. The average value of the five measured bulk densities is shown in Table 2 below. The average bulk density of the compact was calculated by the following formula: 14 The relative density of the compact was calculated by dividing it by the density of a single crystal of NdFe (7.607 g / cc). 14 It is the ratio (unit: %) of the average value of the bulk density of the molded body to the density of the single crystal of B. The relative densities of the molded bodies are shown in Table 2 below. The residual magnetic flux density (B r ) and coercive force (H cj) was measured at room temperature. The remanence and coercivity were measured using a BH tracer. The remanence (unit: T) and coercivity (unit: kA / m) are shown in Table 2 below.

[0068] (Examples 2 to 8 and Comparative Examples 1 to 5) In the ultra-rapid solidification methods of Examples 2 to 8 and Comparative Examples 1 to 5, ΔP and V Ar Each of these was maintained at the value shown in Table 1 below. In Comparative Examples 1, 2, 4, and 5, Ar gas was supplied into the chamber 85 in advance to adjust ΔP to a predetermined value, and then the ultra-rapid solidification method was carried out with the supply of Ar gas into the chamber 85 stopped. Therefore, in Table 1 below, V Ar is written as zero m / s.

[0069] ΔP and V Ar A plurality of ribbons for each of Examples 2 to 8 and Comparative Examples 1 to 5 were produced in the same manner as in Example 1, except for the following: A C / A WHOLE and L 2 Measurement of V / A was carried out only in Examples 2 to 4. C / (V C +V A ) was measured only in Examples 2 to 5 and Comparative Example 2. C / A WHOLE and L 2 / A is shown in the following Table 2. V C / (V C +V A ) are shown in Table 2 below.

[0070] A C / A WHOLE , L 2 / A, and V C / (V C +V A ), the ribbons of Examples 2 to 4 each had the same multiple characteristics as those of Example 1.

[0071] In each of the recesses 9 formed in the crystalline region 7 of Example 5, the crystalline phase, not the amorphous phase, was exposed. C / (V C +V A ) were the values ​​shown in the following Table 2. Except for these characteristics, the ribbon of Example 5 had the same multiple characteristics as those of Example 1.

[0072] The surface F of Comparative Example 1 was flat, and only the amorphous phase of the alloy was exposed over the entire surface F of Comparative Example 1. In other words, the surface F of Comparative Example 1 did not include a crystalline region 7 in which a plurality of recesses 9 were formed. Surface R of Comparative Example 1 included amorphous regions 3 in which only the amorphous phase of the alloy was exposed. Surface R of Comparative Example 1 did not include crystalline regions 7. In other words, only the amorphous phase of the alloy was exposed throughout the entire surface R of Comparative Example 1. Surface R of Comparative Example 1 included multiple concave curved surfaces.

[0073] The surface F of Comparative Example 2 was flat, and only the crystalline phase of the alloy was exposed over the entire surface F of Comparative Example 2. In other words, the surface F of Comparative Example 2 did not include a crystalline region 7 in which a plurality of recesses 9 were formed. Surface R of Comparative Example 2 did not include amorphous regions 3 where only the amorphous phase of the alloy was exposed. Only the crystalline phase of the alloy was exposed throughout surface R of Comparative Example 2. Surface R of Comparative Example 2 included multiple concave curved surfaces.

[0074] In each of the plurality of recesses 9 formed in the crystalline region 7 of Example 6, the crystalline phase, not the amorphous phase, was exposed. Except for this feature, the ribbon of Example 6 had the same features as those of Example 1.

[0075] In each of the plurality of recesses 9 formed in the crystalline region 7 of Example 7, a crystalline phase, not an amorphous phase, was exposed. In the flat portion of the crystalline region 7 of Example 7 excluding the plurality of recesses 9, both the crystalline phase and the amorphous phase were mixed. Except for these features, the ribbon of Example 7 had the same features as those of Example 1.

[0076] In each of the plurality of recesses 9 formed in the crystalline region 7 of Example 8, the crystalline phase, not the amorphous phase, was exposed. Except for this feature, the ribbon of Example 8 had the same features as those of Example 1.

[0077] The surface F of Comparative Example 3 included a crystalline region 7 in which a plurality of recesses 9 were formed. In each of the plurality of recesses 9 formed in the crystalline region 7 of Comparative Example 3, the crystalline phase, not the amorphous phase, was exposed. Surface R of Comparative Example 3 did not include an amorphous region 3 in which only the amorphous phase of the alloy was exposed. Only the crystalline phase of the alloy was exposed throughout surface R of Comparative Example 3. Surface R of Comparative Example 3 included multiple concave curved surfaces.

[0078] The surface F of Comparative Example 4 was flat, and only the amorphous phase of the alloy was exposed over the entire surface F of Comparative Example 4. In other words, the surface F of Comparative Example 4 did not include a crystalline region 7 in which a plurality of recesses 9 were formed. Surface R of Comparative Example 4 included amorphous regions 3 in which only the amorphous phase of the alloy was exposed. Surface R of Comparative Example 4 did not include crystalline regions 7. In other words, only the amorphous phase of the alloy was exposed throughout the entire surface R of Comparative Example 4. Surface R of Comparative Example 4 included multiple concave curved surfaces.

[0079] Surface F of Comparative Example 5 was flat, and only the crystalline phase of the alloy was exposed over the entire surface F of Comparative Example 5. In other words, surface F of Comparative Example 5 did not include a crystalline region 7 in which a plurality of recesses 9 were formed. Surface R of Comparative Example 5 did not include amorphous regions 3 in which only the amorphous phase of the alloy was exposed. Only the crystalline phase of the alloy was exposed throughout surface R of Comparative Example 5. Surface R of Comparative Example 5 included multiple concave curved surfaces.

[0080] The characteristics of the ribbons of Examples 2 to 8 and Comparative Examples 1 to 5 are summarized in Table 1 below.

[0081] The hot forming temperature T for each of Examples 2 to 8 and Comparative Examples 1 to 5 was the value shown in Table 1 below. Compacted bodies for each of Examples 2 to 8 and Comparative Examples 1 to 5 were produced in the same manner as in Example 1, except for the hot forming temperature T. The bulk density and relative density for each of Examples 2 to 8 and Comparative Examples 1 to 5 were measured in the same manner as in Example 1. The bulk density and relative density for each of Examples 2 to 8 and Comparative Examples 1 to 5 are shown in Table 2 below. The remanence and coercivity for each of Examples 2 to 5 and Comparative Examples 1 and 2 were measured in the same manner as in Example 1. The remanence and coercivity for each of Examples 2 to 5 and Comparative Examples 1 and 2 are shown in Table 2 below.

[0082] [Table 1]

[0083] [Table 2]

[0084] In all of Examples 1 to 5 and Comparative Examples 1 and 2, the hot forming temperature T was less than 700°C. The bulk density and relative density of each of Examples 1 to 5 were higher than those of Comparative Examples 1 and 2. The residual magnetic flux density of each of Examples 1 to 5 was higher than those of Comparative Examples 1 and 2. The coercivity of each of Examples 1 to 5 was higher than those of Comparative Examples 1 and 2.

[0085] In all of Examples 6 to 8 and Comparative Examples 3 to 5, the hot forming temperature T was 700° C. or higher. The bulk density and relative density of each of Examples 6 to 8 were higher than those of each of Comparative Examples 3 to 5. [Industrial Applicability]

[0086] For example, a ribbon according to one aspect of the present disclosure may be used as a raw material for a hot-worked magnet. [Explanation of symbols]

[0087] 2...hot-processed magnet, 2cs...cross section of hot-processed magnet (cross section parallel to the easy axis direction of magnetization), 3...amorphous region, 5...concave curved surface, 4...thin ribbon, 4A...main phase particles, 4B...molten metal, R...surface R, F...surface F, 7...crystalline region, 9...recess, 81...cooling roll, 83...container, 85...chamber, C...easy axis direction, AB...direction perpendicular to the easy axis direction of magnetization.

Claims

1. A ribbon including an alloy containing a rare earth element, iron, and boron, the ribbon has a surface R and a surface F located on the back side of the surface R, the surface R includes an amorphous region in which only the amorphous phase of the alloy is exposed, the surface F includes at least a crystalline region in which a crystalline phase of the alloy is exposed; a plurality of recesses are formed in the crystalline region; the surface R does not include the crystalline region in which the plurality of recesses are formed; Thin ribbon.

2. The surface F further includes, in addition to the crystalline region, a region where the amorphous phase is exposed. The ribbon according to claim 1.

3. the amorphous phase is exposed in at least one of the plurality of recesses; The ribbon according to claim 1.

4. the amorphous phase is exposed in at least one of the recesses, an area ratio of the crystalline phase in the crystalline region is 0.18 or more and 0.90 or less; The ribbon according to claim 1.

5. the amorphous phase is exposed in at least one of the recesses, The perimeter of one of the recesses as observed from a direction perpendicular to the surface F is represented as L, The area of ​​one of the recesses as viewed from a direction perpendicular to the surface F is represented as A, L ２ / A is 100 or more and 400 or less, The ribbon according to claim 1.

6. the crystalline phase is exposed in all of the plurality of recesses; The ribbon according to claim 1.

7. the amorphous region includes a plurality of concave curved surfaces; The ribbon according to claim 1.

8. Used as a raw material for hot-processed magnets, The ribbon according to claim 1.

9. The thickness of the ribbon is 10 μm or more and 60 μm or less. The ribbon according to claim 1.

10. The volume of the crystalline phase contained in the ribbon is V Ｃ is expressed as The volume of the amorphous phase contained in the ribbon is V Ａ is expressed as V Ｃ / (V Ｃ +V Ａ ) is greater than 0 and less than or equal to 0.40; The ribbon according to claim 1.

11. A step of pulverizing the ribbon according to any one of claims 1 to 10 to obtain an alloy powder; a step of obtaining a compact by pressing the alloy powder while heating; obtaining a magnet substrate by hot plastic working of the compact; Equipped with Manufacturing method of hot-deformed magnets.

Images