Rare earth sintered magnet, method for manufacturing rare earth sintered magnet, rotor, and rotating machine

Abstract

A rare earth sintered magnet (1) has: a main phase (10) that satisfies the general formula (Nd, Pr, R)-Fe-B-M and contains crystal grains based on an Nd2Fe14B crystal structure, where R is one or more rare earth elements selected from the group consisting of Nd and Pr, and M is one or more elements selected from the group consisting of Ga, Al, Cu, and Co; and a sub-phase (20) formed between the main phases. The main phase has a core part and a shell part covering the core part. When the Nd concentration in the core portion is CNd and the Pr concentration in the core portion is CPr, the main phase has a first main phase (11) in which CNd > CPr and a second main phase (12) in which CNd < CPr. The first main phase is mixed with the second main phase. The sub-phase has a first crystalline sub-phase (21) and a second crystalline sub-phase (22), the main component of which is an oxide phase represented by (Nd, Pr, R)-O containing element M as a trace component. The concentration of the element M in the second pair is higher than that in the first pair.

Description

Technical Field

[0001] This disclosure relates to a permanent magnet, namely a rare earth sintered magnet, which is a material containing rare earth elements sintered into a permanent magnet, a method for manufacturing a rare earth sintered magnet, a rotor, and a rotating machine. Background Technology

[0002] Given that the tetragonal crystal R2T 14 RTB-based permanent magnets are predominantly composed of boron intermetallic compounds. In these magnets, R represents rare earth elements, T represents Fe (iron) or transition metals such as Fe partially replaced by Co (cobalt), and B represents boron. RTB-based permanent magnets are used in various high-value-added components, primarily industrial motors. In particular, Nd-Fe-B sintered magnets with Nd (neodymium) as R exhibit excellent magnetic properties and are therefore used in various components. Furthermore, since industrial motors are often used in high-temperature environments exceeding 100°C, the addition of heavy rare earth elements such as Dy (dysprosium) to Nd-TB sintered magnets has been explored to improve coercivity.

[0003] In recent years, the production of Nd-Fe-B sintered magnets has been expanding, leading to increased consumption of Nd and heavy rare earth elements such as Dy and Tb (terbium). However, Nd and heavy rare earth elements are expensive and geographically unevenly distributed, posing procurement risks. Therefore, research is underway to develop technologies to curb the consumption of Nd and heavy rare earth elements.

[0004] Patent document 1 discloses an RTB-based sintered magnet, which comprises R2T 14 RTB-based sintered magnets with boron as the main phase particles, wherein R is one or more rare earth elements with RH as an essential heavy rare earth element, T is one or more transition metal elements with Fe or Fe and Co as essential transition metal elements, and B is boron. A portion of the main phase particles contains multiple low-heavy rare earth element crystal phases and multiple non-magnetic R-rich phases. Among them, the low-heavy rare earth element crystal phases include R2T. 14 B crystal is a phase in which the concentration of heavy rare earth elements is relatively low compared to the overall concentration of heavy rare earth elements in the main phase particles. The non-magnetic R-rich phase is a phase with an R content of 70 atomic% or more and 100 atomic% or less. Furthermore, a portion of the main phase particles has a core-shell structure, comprising a core and a shell surrounding the core with a lower total heavy rare earth element concentration than the core. According to the technology described in Patent Document 1, an RTB-based sintered magnet with improved coercivity and low cost is obtained.

[0005] Patent document 2 discloses a method for manufacturing a rare earth magnet, which includes: manufacturing a rare earth magnet composed of (R1) 1-x R2 x ) a TM b B c Md The process involves three steps: a first step of constructing a sintered body with a microstructure consisting of a main phase and grain boundary phases; a second step of thermoplastic processing of the sintered body to manufacture a rare-earth magnet precursor; and a third step of diffusing and penetrating the molten R3-M modified alloy into the grain boundary phases of the rare-earth magnet precursor to manufacture a rare-earth magnet. Specifically, R1 is one or more rare-earth elements including Y (yttrium), R2 is a rare-earth element different from R1, TM is one or more transition metals including Fe, Ni (nickel), and Co, B is boron, and M is one or more of Ti (titanium), Ga (gallium), Zn (zinc), Si (silicon), Al (aluminum), Nb (niobium), Zr (zirconium), Ni, Co, Mn (manganese), V (vanadium), W (tungsten), Ta (tantalum), Ge (germanium), Cu (copper), Cr (chromium), Hf (hafnium), Mo (molybdenum), P (phosphorus), C (carbon), Mg (magnesium), Hg (mercury), Ag (silver), and Au (gold). Furthermore, x, a, b, c, and d are 0.01≤x≤1, 12≤a≤20, b=100-acd, 5≤c≤20, and 0≤d≤3, all representing atomic percentages. Additionally, R3 is a rare earth element containing R1 and R2. The thermoplastic processing performed on the sintered body will be referred to as hot processing. According to the technology described in Patent Document 2, it is possible to manufacture rare earth magnets that reduce heavy rare earth elements and possess excellent magnetization and coercivity properties, even with a high principal phase index.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2018-174313

[0009] Patent Document 2: Japanese Patent Application Publication No. 2015-153813 Summary of the Invention

[0010] The problem that the invention aims to solve

[0011] However, regarding the RTB-based sintered magnet described in Patent Document 1, since the phase containing heavy rare earth elements exists within the main phase, even if the coercivity can be improved, the remanent magnetic flux density required for industrial motors and the like cannot be obtained, and the magnetic properties may decrease due to thermal load. Furthermore, regarding the rare earth magnet manufactured using the manufacturing method described in Patent Document 2, while it is possible to reduce the amount of heavy rare earth elements and improve coercivity, the manufacturing method includes hot working, resulting in a smaller particle size of the main phase. This leads to problems with the remanent magnetic flux density and magnetic properties of the manufactured rare earth magnet.

[0012] This disclosure is made in view of the above and aims to obtain rare earth sintered magnets that do not use heavy rare earth elements, do not reduce the residual magnetic flux density and magnetic properties compared with the past, and can improve coercivity.

[0013] Methods for solving problems

[0014] To address the aforementioned issues and achieve the objectives, the rare-earth sintered magnet disclosed herein comprises: a main phase in which R is selected from one or more rare-earth elements other than Nd and Pr (praseodymium), and M is selected from one or more elements other than Ga, Al, Cu, and Co, wherein the main phase satisfies the general formula (Nd, Pr, R)-Fe-BM, and contains Nd2Fe. 14 B is a crystal structure based on grains; and secondary phases, which form between the main phases. The main phase has a core and a shell covering the core. When the concentration of Nd in the core is set as CNd and the concentration of Pr in the core is set as CPr, the main phase has a first main phase with CNd > CPr and a second main phase with CNd < CPr. The first and second main phases are mixed. The secondary phases have a first secondary phase and a second secondary phase with crystalline structure mainly composed of oxide phases (Nd, Pr, R)-O containing element M as a trace component. The second secondary phase has a higher concentration of element M than the first secondary phase.

[0015] The effects of the invention

[0016] The rare earth sintered magnet disclosed herein produces the following effects: it does not use heavy rare earth elements and can improve coercivity without reducing the residual magnetic flux density and magnetic properties compared to the past. Attached Figure Description

[0017] Figure 1 The diagram schematically illustrates an example of the structure of a rare-earth sintered magnet in its sintering state according to Embodiment 1.

[0018] Figure 2 The diagram schematically illustrates an example of the structure of a rare-earth sintered magnet in its sintering state according to Embodiment 2.

[0019] Figure 3 To show tetragonal Nd2Fe 14 A diagram of atomic sites in the B crystal structure.

[0020] Figure 4 This is a flowchart illustrating an example of the steps in a method for manufacturing a rare-earth sintered magnet alloy according to Embodiment 3.

[0021] Figure 5 This is a flowchart illustrating an example of the steps in a method for manufacturing a rare-earth sintered magnet according to Embodiment 3.

[0022] Figure 6 A cross-sectional view is shown schematically, illustrating an example of the configuration of a rotor equipped with a rare-earth sintered magnet according to Embodiment 4.

[0023] Figure 7A cross-sectional view is shown schematically as an example of the configuration of the rotating machine according to Embodiment 5.

[0024] Figure 8 The image shows a compositional image obtained by analyzing the cross-section of rare earth sintered magnets according to Examples 1 to 8 using a Field Emission-Electron Probe Micro Analyzer (FE-EPMA).

[0025] Figure 9 The elemental mapping of Nd obtained by FE-EPMA analysis of cross-sections of rare earth sintered magnets according to Examples 1 to 8.

[0026] Figure 10 The elemental mapping of Pr obtained by FE-EPMA analysis of cross sections of rare earth sintered magnets according to Examples 1 to 8.

[0027] Figure 11 The elemental mapping of Co obtained by FE-EPMA analysis of cross sections of rare earth sintered magnets according to Examples 1 to 8.

[0028] Figure 12 The elemental mapping of O (oxygen) was obtained by analyzing the cross-sections of rare earth sintered magnets according to Examples 1 to 8 using FE-EPMA.

[0029] Figure 13 The elemental mapping of La (lanthanum) was obtained by analyzing the cross-sections of rare earth sintered magnets according to Examples 1 to 8 using FE-EPMA.

[0030] Figure 14 The elemental mapping of Sm (samarium) was obtained by analyzing the cross-sections of rare earth sintered magnets according to Examples 1 to 8 using FE-EPMA. Detailed Implementation

[0031] The following description, based on the accompanying drawings, details the rare earth sintered magnet, the method for manufacturing the rare earth sintered magnet, the rotor, and the rotating machine related to the embodiments of this disclosure.

[0032] Implementation method 1.

[0033] Figure 1 This diagram schematically illustrates an example of the structure of a rare-earth sintered magnet in its sintering state according to Embodiment 1. The rare-earth sintered magnet 1 according to Embodiment 1 has a structure satisfying the general formula (Nd, Pr, R)-Fe-BM, containing Nd2Fe... 14The main phase 10 is based on a B crystal structure; and the secondary phase 20 exists between the main phase 10 and the secondary phase 20. The main phase 10 has a core and a shell covering the core. R is one or more rare earth elements selected from Nd and Pr. M is one or more elements selected from Ga, Al, Cu, and Co. The shell has a different composition from the core and is arranged to cover the core.

[0034] Specifically, according to Embodiment 1, if the rare earth sintered magnet 1, that is, the rare earth sintered magnet 1 containing the main phase 10 and the secondary phase 20, is made such that R is a rare earth element other than Nd and Pr, and M is one or more elements selected from Ga, Al, Cu, and Co, then the general formula is derived from (Nd... a Pr b R c Fe d B e M f Let a, b, c, d, e, and f preferably satisfy the following relation.

[0035] 5≤a+b≤20

[0036] 0 < c < (a + b)

[0037] 70≤d≤90

[0038] 0.5≤e≤10

[0039] 0≤f≤5

[0040] a+b+c+d+e+f = 100 atoms

[0041] The main phase 10 has a tetragonal R2Fe structure in which a portion of the Nd sites are replaced by Pr and one or more rare earth elements R selected from Nd and Pr. 14 B crystal structure. That is, the main phase 10 has a (Nd, Pr, R)2Fe crystal structure. 14 The composition formula of B. Element M can enter the main phase 10. When element M is a transition element, i.e., Co or Cu, it is assumed that element M will enter Nd₂Fe. 14 Part of the Fe sites in the B crystal structure are replaced.

[0042] In the rare earth sintered magnet 1 according to Embodiment 1, when the Nd concentration in the core is set to CNd and the Pr concentration in the core is set to CPr, the main phase 10 has a first main phase 11 with CNd > CPr and a second main phase 12 with CNd < CPr, and the first main phase 11 and the second main phase 12 are mixed. The first main phase 11 has a core 11c and a shell 11s that has a different composition from the core 11c and covers the core 11c. The second main phase 12 has a core 12c and a shell 12s that has a different composition from the core 12c and covers the core 12c. In the core 11c of the first main phase 11, CNd > CPr, and in the core 12c of the second main phase 12, CNd < CPr.

[0043] That is, the rare-earth sintered magnet 1 contains two main phases 10: a first main phase 11 and a second main phase 12. If we focus on the cores 11c and 12c of these two main phases 10, it means that in the first main phase 11, the concentration of Nd is higher than that of Pr, and conversely, in the second main phase 12, the concentration of Pr is higher than that of Nd. By mixing the two main phases 10 with core-shell structures and anisotropic magnetic fields (i.e., magnetically anisotropic), Nd can be reduced, and remanent magnetic flux density and coercivity can be increased while maintaining good magnetization without adding heavy rare-earth elements. Furthermore, by adding element M, the coercivity is significantly improved, thus also helping to suppress the decrease in magnetic properties associated with temperature changes.

[0044] The concentration difference represented by "first principal phase 11 where CNd > CPr and second principal phase 12 where CNd < CPr" indicates a clear difference in the detection intensity of Nd and Pr, achieved through mapping analysis using an Electron Probe Micro Analyzer (EPMA). Specifically, taking the first principal phase 11 as an example, it means that for the Nd concentration in the core 11c, the EPMA detection intensity is higher than the average Nd detection intensity, while for the Pr concentration, the EPMA detection intensity shows a value near the lower limit of the Pr detection intensity, or the EPMA detection intensity is lower than the average Pr detection intensity. The second principal phase 12 can be considered the opposite of the first principal phase 11.

[0045] Furthermore, according to Embodiment 1, when the concentration of Nd in the core 11c of the first main phase 11 is set to C1Nd, the concentration of Nd in the core 12c of the second main phase 12 is set to C2Nd, the concentration of Pr in the core 11c of the first main phase 11 is set to C1Pr, and the concentration of Pr in the core 12c of the second main phase 12 is set to C2Pr, the relationship C1Nd > C2Nd and C1Pr < C2Pr is satisfied. That is, for the concentration of Nd, the core 11c of the first main phase 11 is higher than that of the core 12c of the second main phase 12; conversely, for the concentration of Pr, the core 12c of the second main phase 12 is higher than that of the core 11c of the first main phase 11. This concentration difference also refers to the difference in the detection intensity of Nd and Pr according to the mapping analysis using the above-described EPMA. Specifically, at the Nd concentration, this means that the average detection intensity of EPMA of Nd in the core 11c of the first main phase 11 is higher than the average detection intensity of Nd, while the average detection intensity of EPMA of Nd in the core 12c of the second main phase 12 is lower than the average detection intensity of Nd. At the Pr concentration, this means that the average detection intensity of EPMA of Pr in the core 12c of the second main phase 12 is higher than the average detection intensity of Pr, while the average detection intensity of EPMA of Pr in the core 11c of the first main phase 11 is lower than the average detection intensity of Pr. That is, Pr is abundant in the core 12c of the second main phase 12 where the Nd concentration is low, and conversely, Nd is abundant in the core 11c of the first main phase 11 where the Pr concentration is low. By controlling the microstructure to this state, a rare-earth sintered magnet 1 with excellent magnetic properties can be obtained.

[0046] Furthermore, in the rare earth sintered magnet 1 according to Embodiment 1, a first principal phase 11, in which CNd > CPr, is present in greater quantities than a second principal phase 12, where CNd < CPr. In other words, this means that it has Nd2Fe 14 The first principal phase 11 of the composition of B has a ratio of Pr2Fe 14 The composition of B has a large number of second principal phases 12. This is because the addition of Nd2Fe... 14 The first principal phase 11 of the composition of B is increased with Pr2Fe 14 Compared to the second principal phase 12 of the B composition, superior magnetic and temperature properties can be obtained. Furthermore, by controlling the microstructure to this extent, overall grain refinement is also suppressed, thus ensuring magnetization and achieving magnetic properties superior to those of the past.

[0047] Furthermore, in the rare earth sintered magnet 1 according to Embodiment 1, attention is paid to the shell portions 11s and 12s with a core-shell structure. When the Nd concentration in the shell portions 11s and 12s is set to SNd and the Pr concentration in the shell portions 11s and 12s is set to SPr, the first main phase 11 satisfies the relationship CNd > SNd and CPr < SPr, and the second main phase 12 satisfies the relationship CNd < SNd and CPr > SPr. Specifically, for the shell portion 11s of the first main phase 11, the concentration of Nd is lower and the concentration of Pr is higher than that of the core portion 11c. For the shell portion 12s of the second main phase 12, the concentration of Pr is lower and the concentration of Nd is higher than that of the core portion 12c. By forming a main phase 10 with a shell portion 11s having a high concentration of Pr, as in the first main phase 11, the coercivity can be improved. Furthermore, by forming a main phase 10 with a high Nd concentration in the shell 12s, similar to the second main phase 12, it is possible to suppress the decrease in remanent magnetic flux density while maintaining coercivity. By selectively controlling the microstructure to achieve this, the rare-earth sintered magnet 1 can exhibit superior magnetic properties compared to the past.

[0048] Furthermore, the average grain size of the main phase 10 is preferably set to 100 μm or less, and more preferably 0.5 μm or more and 50 μm or less to improve magnetic properties. Furthermore, by setting it to about 1 μm or more and 10 μm or less, a grain size different from the fine structure manufactured by heat processing is achieved, which can maintain good magnetic properties and produce a rare earth sintered magnet 1 with better magnetic properties than before.

[0049] The secondary phase 20 comprises: a crystalline first secondary phase 21, whose main component is an oxide phase represented by (Nd, Pr, R)-O containing element M as a trace element, and a crystalline second secondary phase 22, whose main component is an oxide phase represented by (Nd, Pr, R)-O containing element M as a trace element. O represents oxygen. The crystalline secondary phase 20 is a collective term for the crystalline first secondary phase 21 and the crystalline second secondary phase 22. Here, (Nd, Pr, R) means that a portion of Nd and Pr are replaced by rare earth elements R other than Nd and Pr. The R in the first secondary phase 21 and the R in the second secondary phase 22 can be the same rare earth element, a portion of different rare earth elements, or different rare earth elements. It should be noted that the main component element is listed in parentheses here; therefore, the first secondary phase 21 and the second secondary phase 22 may contain trace amounts of other components besides the elements shown in parentheses.

[0050] Subphase 20, namely the first subphase 21 and the second subphase 22, as described above, contains element M as a trace component. Regarding the concentration of element M in the first subphase 21 and the second subphase 22, the concentration in the second subphase 22 is higher than that in the first subphase 21. That is, when the concentration of element M in the first subphase 21 is set as Cs1M and the concentration of element M in the second subphase 22 is set as Cs2M, the relationship Cs1M < Cs2M is satisfied.

[0051] The statement that "in terms of the concentration of element M, the second subphase 22 is higher than the first subphase 21" means that, using EPMA mapping analysis, the average detection intensity of element M in the second subphase 22 is higher than that in the first subphase 21. More specifically, it means that the average intensity of element M detected by EPMA in the second subphase 22 is higher than the average intensity of element M detected by EPMA, while the average intensity of element M detected by EPMA in the first subphase 21 is lower than the average intensity of element M detected by EPMA.

[0052] Furthermore, in the secondary phase 20, element M exists at a high concentration in the second secondary phase 22, thus forming a non-magnetic phase that magnetically divides the main phases 10, contributing to the improvement of magnetic properties. That is, by making the concentration of element M in the second secondary phase 22 higher than that in the first secondary phase 21, high magnetic properties, especially coercivity, can be obtained without adding heavy rare earth elements, and the decrease in magnetic properties associated with temperature increases can be suppressed.

[0053] According to Embodiment 1, the rare earth sintered magnet 1 comprises: a main phase 10, wherein when R is one or more rare earth elements selected from Nd and Pr, and M is one or more elements selected from Ga, Al, Cu, and Co, the main phase 10 satisfies the general formula (Nd, Pr, R)-Fe-BM, containing Nd2Fe 14 The primary phase 10 consists of grains based on a B crystal structure and a secondary phase 20, which exists between the primary phase 10 and the secondary phase 10. The primary phase 10 has cores 11c and 12c and shells 11s and 12s covering the cores 11c and 12c. Furthermore, the primary phase 10 has a first primary phase 11 with CNd > CPr and a second primary phase 12 with CNd < CPr, the first primary phase 11 and the second primary phase 12 being mixed. The secondary phase 20 has a first secondary phase 21 and a second secondary phase 22 that are crystalline and have oxide phases (Nd, Pr, R)-O containing element M as trace elements as the main components. The concentration of element M in the second secondary phase 22 is higher than that in the first secondary phase 21. With this configuration, a rare-earth sintered magnet 1 with high magnetic properties, specifically coercivity, and suppressed decrease in magnetic properties associated with temperature rise can be obtained without adding heavy rare-earth elements.

[0054] Furthermore, in the rare-earth sintered magnet 1 according to Embodiment 1, the first principal phase 11 and the second principal phase 12 are made to satisfy the relationship C1Nd > C2Nd and C1Pr < C2Pr. Alternatively, the number of the first principal phase 11 is greater than the number of the second principal phase 12. Alternatively, the first principal phase 11 is made to satisfy the relationship CNd > SNd and CPr < SPr, and the second principal phase 12 is made to satisfy the relationship CNd < SNd and CPr > SPr. Thus, by suppressing the use of Nd and without adding heavy rare-earth elements, a rare-earth sintered magnet 1 with improved magnetic properties and magnetization can be obtained.

[0055] Implementation method 2.

[0056] In Embodiment 2, the case where La and Sm are selected as rare earth elements R in the rare earth sintered magnet 1 according to Embodiment 1 is shown.

[0057] Figure 2 This diagram schematically illustrates an example of the structure of the rare-earth sintered magnet in its sintered state according to Embodiment 2. It should be noted that the same reference numerals are used for the same constituent elements as in Embodiment 1, and their descriptions are omitted. The rare-earth sintered magnet 1 according to Embodiment 2 has a primary phase 10 and a secondary phase 20. The primary phase 10, as described in Embodiment 1, includes a first primary phase 11 and a second primary phase 12. The secondary phase 20, as described in Embodiment 1, includes a first secondary phase 21 and a second secondary phase 22.

[0058] When La and Sm are selected as the rare earth elements R, the magnetic properties are improved and the magnetization effect is further enhanced compared to the past, while suppressing the use of Nd and without using heavy rare earth elements. In this example, the main phase 10 has (Nd, Pr, La, Sm)2Fe 14 The composition of B. To make it tetragonal R2Fe 14 The reason for using rare earth elements R, which contain La and Sm, in the rare earth sintered magnet 1 with a B crystal structure is that, based on calculations of magnetic interaction energy using the molecular orbital method, by adding La and Sm to the composition, a practical rare earth sintered magnet 1 can be obtained that can significantly suppress the decrease in magnetic properties associated with temperature increases. Furthermore, by intentionally causing La and Sm to segregate at grain boundaries, as an example of the secondary phase 20, Nd and Pr can be relatively diffused in the main phase 10, thereby improving the crystal magnetic anisotropy of the main phase 10. Thus, a core-shell structure with both high and low magnetic anisotropy regions is formed within the main phase 10, resulting in a rare earth sintered magnet 1 that easily produces a mixture of a first main phase 11 (CNd > CPr) and a second main phase 12 (CNd < CPr).

[0059] It should be noted that if too much La and Sm are added, the amount of Nd and Pr, which have high magnetic anisotropy constants and high saturation magnetic polarization, will decrease, leading to a reduction in magnetic properties. Therefore, when the composition ratios of Nd, Pr, La, and Sm are set to A, B, C, and D, it is preferable that (A+B) > (C+D).

[0060] In the rare-earth sintered magnet 1 according to Embodiment 2, when R = La, Sm, the secondary phase 20 has: a first crystalline secondary phase 21 with a (Nd, Pr, La, Sm)-O oxide phase containing element M as a trace component as the main component; and a second crystalline secondary phase 22 with a (Nd, Pr, La)-O oxide phase containing element M as a trace component as the main component. Thus, the first secondary phase 21 has a higher Sm concentration than the second secondary phase 22 in the secondary phase 20. That is, in the secondary phase 20 of the rare-earth sintered magnet 1, the first secondary phase 21 forms a Sm-enriched portion with a higher Sm concentration than the second secondary phase 22. This results in the following effect: not only is the decrease in magnetic properties at room temperature suppressed, but the decrease in magnetic properties associated with temperature increases is also suppressed.

[0061] Furthermore, within the first subphase 21, there are sometimes regions with high Sm concentrations, i.e., high-concentration regions 41, and regions with low Sm concentrations, i.e., low-concentration regions 42. In such cases, sometimes the concentration of element M entering the first subphase 21 is lower than that of the surrounding region, i.e., low-concentration region 42. In this situation, the concentration of element M in low-concentration region 42 becomes higher than the concentration of element M in high-concentration region 41.

[0062] Regarding the concentration of element M, as explained in Embodiment 1, the second subphase 22 has a higher concentration than the first subphase 21. Thus, Sm and element M segregate in different subphases 20. Sm exists at a high concentration in the first subphase 21, thereby causing Nd to diffuse relatively in the main phase 10, increasing the crystal magnetic anisotropy of the main phase 10. Furthermore, Sm also exists within the grains of the main phase 10, thus binding in the same magnetization direction as the ferromagnetic material, Fe, contributing to the increase in remanent magnetic flux density. Element M exists at a high concentration in the second subphase 22, thus forming a nonmagnetic phase that magnetically separates the main phases 10, contributing to the improvement of magnetic properties. By having Sm and element M exist at high concentrations in different subphases 20, both remanent magnetic flux density and coercivity can be improved.

[0063] The statement "in terms of Sm concentration, the first subphase 21 is higher than the second subphase 22" means that, using EPMA mapping analysis, the average detection intensity of Sm in the first subphase 21 is higher than that in the second subphase 22. More specifically, it means that the average Sm intensity detected by EPMA in the first subphase 21 is higher than the average Sm intensity detected by EPMA, while the average Sm intensity detected by EPMA in the second subphase 22 is lower than the average Sm intensity detected by EPMA.

[0064] The crystalline secondary phase 20 is a collective term for the crystalline first secondary phase 21 and the crystalline second secondary phase 22, existing between the main phase 10. The crystalline first secondary phase 21 is represented by (Nd, Pr, La, Sm)-O, containing element M as a trace component, and the crystalline second secondary phase 22 is represented by (Nd, Pr, La)-O, containing element M as a trace component. Here, (Nd, Pr, La, Sm) means that a portion of Nd and Pr is replaced by La and Sm. It should be noted that the main component elements are listed in parentheses here; therefore, the first secondary phase 21 and the second secondary phase 22 may contain trace amounts of other components besides those shown in parentheses. In one example, the second secondary phase 22, represented by (Nd, Pr, La)-O, containing element M as a trace component, contains trace amounts of Sm.

[0065] In the rare earth sintered magnet 1 according to Embodiment 2, a concentration difference of La and Sm exists between the main phase 10 and the secondary phase 20, and La and Sm segregate in the secondary phase 20 compared to the main phase 10. That is, the sum of the La concentrations in the first secondary phase 21 and the second secondary phase 22 is greater than or equal to the La concentration in the main phase 10, and the sum of the Sm concentrations in the first secondary phase 21 and the second secondary phase 22 is greater than or equal to the Sm concentration in the main phase 10. Specifically, the La and Sm concentrations in the secondary phase 20 are greater than or equal to the La and Sm concentrations in the main phase 10. Here, the La concentration in the main phase 10 is the sum of the La concentrations in the first main phase 11 and the second main phase 12. That is, the sum of the La concentrations in the first secondary phase 21 and the second secondary phase 22 is higher than the sum of the La concentrations in the first main phase 11 and the second main phase 12. In addition, the Sm concentration in the main phase 10 is the sum of the Sm concentrations in the first main phase 11 and the second main phase 12. That is, the sum of the concentrations of Sm in the first secondary phase 21 and the second secondary phase 22 is higher than the sum of the concentrations of Sm in the first primary phase 11 and the second primary phase 12.

[0066] Here, when the La concentration in the main phase 10 is set as X, the La concentration in the first subphase 21 is set as X1, the La concentration in the second subphase 22 is set as X2, the Sm concentration in the main phase 10 is set as Y, the Sm concentration in the first subphase 21 is set as Y1, and the Sm concentration in the second subphase 22 is set as Y2, the following relationship (1) is satisfied.

[0067] 1<(Y1+Y2) / Y<(X1+X2) / X (1)

[0068] Furthermore, from the perspective of improving magnetic properties, the concentrations of Nd and Pr contained in the main phase 10 satisfy the following relationships (2) and (3).

[0069] (CNd+SNd)>(X+Y) (2)

[0070] (CPr+SPr)>(X+Y) (3)

[0071] It should be noted that, as described above, the concentration of La in the main phase 10 is the sum of the concentrations of La in the first main phase 11 and the second main phase 12, and the concentration of Sm in the main phase 10 is the sum of the concentrations of Sm in the first main phase 11 and the second main phase 12. This indicates that both La and Sm segregate in the secondary phase 20 compared to the main phase 10. However, under localized observation, the sum of the individual concentrations of La and Sm in the first main phase 11 and the second main phase 12 may not always satisfy the above relationship with the sum of the individual concentrations of La and Sm in the first secondary phase 21 and the second secondary phase 22. Therefore, more specifically, the concentration of La in the main phase 10 represents the average concentration of La in the first main phase 11 and the second main phase 12, and the concentration of Sm in the main phase 10 represents the average concentration of Sm in the first main phase 11 and the second main phase 12. In this case, the concentration of La in subphase 20, i.e., the sum of the concentrations of La in the first subphase 21 and the second subphase 22, means the average concentration of La in the first subphase 21 and the second subphase 22, and the concentration of Sm in subphase 20, i.e., the sum of the concentrations of Sm in the first subphase 21 and the second subphase 22, means the average concentration of Sm in the first subphase 21 and the second subphase 22.

[0072] La exists at a high concentration at grain boundaries during manufacturing processes, particularly heat treatment, thereby relatively causing Nd and Pr to diffuse in the main phase 10. As a result, Nd and Pr in the main phase 10 of the rare earth sintered magnet 1 in Embodiment 2 are not consumed at grain boundaries, and the crystal magnetic anisotropy is improved. As for Sm, it also exists at a high concentration in the secondary phase 20, especially the first secondary phase 21, compared to the main phase 10, thus similarly causing Nd to diffuse in the main phase 10, thereby improving the crystal magnetic anisotropy.

[0073] Secondly, for La and Sm in tetragonal R2Fe 14 Please explain which atomic sites in the B crystal structure are replaced. Figure 3 To show tetragonal Nd2Fe 14 A diagram of the atomic sites in the B crystal structure. It should be noted that... Figure 3The crystal structure shown is described in, in one example, in the following reference document 1. Figure 1 Regarding the substituted site, the stabilization energy produced by the substitution is calculated using band structure calculations and the molecular field approximation of the Heisenberg model, and the determination is made based on the value of this energy.

[0074] (Reference Technical Document 1) JF Herbst et al. "Relationships between crystal structure and magnetic properties in Nd2Fe 14 B. PHYSICAL REVIEW B. 1984, Vol. 29, No. 7, pp. 4176-4178.

[0075] First, the calculation method for the stabilization energy of La is explained. The stabilization energy of La can be calculated using Nd8Fe. 56 B4 crystal unit, utilizing (Nd7La1)Fe 56 B4+Nd and Nd8(Fe) 55 The energy difference between La1)B4+Fe and Fe2) is calculated. The lower the energy value, the more stable the atom at that site is when it is replaced. That is, for La, the atom at the lowest energy site is more easily replaced. Based on this calculation, it is assumed that when La is replaced by its original atom, the tetragonal R2Fe... 14 The lattice constant in the B crystal structure does not change with different atomic radii. Table 1 shows the stabilization energy of La at each substitution site when the ambient temperature is changed.

[0076] [Table 1]

[0077]

[0078] According to Table 1, stable substitution sites for La are Nd(f) sites at temperatures above 1000 K and Fe(c) sites at temperatures of 293 K and 500 K. Regarding the rare-earth sintered magnet 1 according to Embodiment 2, as described later, the raw material for the rare-earth sintered magnet 1 is heated to a temperature above 1000 K and melted, then rapidly cooled. Therefore, it is considered that the raw material for the rare-earth sintered magnet 1 is maintained at a temperature above 1000 K, i.e., above 727 °C, preferably around 1300 K, i.e., 1027 °C. At this time, it is considered that La substitution occurs at either the Nd(f) site or the Nd(g) site. Here, it is considered that La preferentially substitutes at the energy-stable Nd(f) site, but substitution can also occur at the Nd(g) site with a small energy difference among the substitution sites for La. Therefore, the Nd(g) site is also listed as a candidate substitution site for La.

[0079] Furthermore, when manufacturing the rare earth sintered magnet 1 using the manufacturing method described later, although the sintering temperature is above 1000K, the temperature range where the Fe(c) sites listed in Table 1 are energy-stable is maintained multiple times through the first aging process, the second aging process, the third aging process, the fourth aging process, and the cooling process described later. In other words, the La substitution at the Nd sites of the main phase 10 is maintained in an unstable energy state. That is, in the raw material stage of the rare earth sintered magnet 1, La is mainly substituted at the Nd sites of the main phase 10, but in the rare earth sintered magnet 1 manufactured using the manufacturing method described later, by repeatedly maintaining the rare earth sintered magnet 1 in an unstable energy state temperature range for the Nd sites of the main phase 10, a certain degree of La is selectively released from the Nd sites of the main phase 10, resulting in La segregation in the secondary phase 20. As a result, the main phase 10 promotes the formation of a core-shell structure.

[0080] Secondly, the calculation method for the stabilization energy of Sm is explained. The stabilization energy of Sm can be calculated using (Nd7Sm1)Fe 56 B4+Nd and Nd8(Fe) 55 The energy difference of Sm1)B4+Fe is obtained. For tetragonal R2Fe 14 The lattice constant of the B crystal structure does not change with the substitution of atoms, which is the same as the case of La. Table 2 shows the stabilization energy of Sm at each substitution site when the ambient temperature is changed.

[0081] [Table 2]

[0082]

[0083] According to Table 2, the stable substitution sites of Sm differ from those of La; at all temperatures, they are Nd(g) sites. For Sm, it is assumed that the energy-stable Nd(g) sites preferentially substitute, but among the substitution sites in Sm, substitution can also occur at Nd(f) sites with small energy differences.

[0084] When the rare-earth sintered magnet 1 is manufactured using the method described later, the substitution at the Nd(g) sites in the main phase 10 is most stable in terms of energy. However, as mentioned above, by maintaining the temperature range in which the substitution of La at the Nd sites in the main phase 10 becomes unstable, a portion of Sm is also released from the Nd sites in the main phase 10 along with La and segregates in the secondary phase 20. As a result, there is a concentration difference between the main phase 10 and the secondary phase 20, where the sum of the La concentrations in the first secondary phase 21 and the second secondary phase 22 is greater than the La concentration in the main phase 10, and the sum of the Sm concentrations in the first secondary phase 21 and the second secondary phase 22 is greater than the Sm concentration in the main phase 10. More specifically, the average La concentration in the first secondary phase 21 and the second secondary phase 22 is greater than the average La concentration in the first main phase 11 and the second main phase 12, and the average Sm concentration in the first secondary phase 21 and the second secondary phase 22 is greater than the average Sm concentration in the first main phase 11 and the second main phase 12. That is, it can be said that La and Sm segregate in the secondary phase 20.

[0085] Comparing La and Sm, from an energy perspective, it is evident that La, maintained within a temperature range of unstable energy states, tends to overwhelmingly segregate in the secondary phase 20. Therefore, in the case of a rare-earth sintered magnet 1 prepared with La and Sm concentrations at equal levels, the segregation ratio of La in the secondary phase 20 increases for the La and Sm present in the rare-earth sintered magnet 1. By repeatedly maintaining the rare-earth sintered magnet 1 within this temperature range, a concentration gradient of Sm with a smaller segregation ratio is generated in the secondary phase 20, forming a first secondary phase 21 and a second secondary phase 22. This promotes the formation of a core-shell structure in the main phase 10.

[0086] Here, as Figure 3 Nd is described representatively as shown, but as represented by Di (didymium), Nd and Pr are produced as a mixture, so the energy levels of Nd and Pr are considered to be close. Therefore, it can be said that the same applies even if Nd is replaced by Pr. By incorporating Nd and Pr, both of which exist in rare earth sintered magnets 1, it is possible to form a main phase 10 with two core-shell structures.

[0087] As described above, the rare earth sintered magnet 1 of Embodiment 2 comprises: a main phase 10, wherein when R is one or more rare earth elements selected from Nd and Pr, and M is one or more elements selected from Ga, Al, Cu, and Co, the main phase 10 satisfies the general formula (Nd, Pr, R)-Fe-BM, containing Nd2Fe 14B is a grain based on a crystal structure; and a secondary phase 20, which exists between the main phase 10 and the main phase 10. The main phase 10 has cores 11c and 12c and shells 11s and 12s covering the cores 11c and 12c. Assuming R = La and Sm, the secondary phase 20 has a first crystalline secondary phase 21 with a main component being an oxide phase of (Nd, Pr, La, Sm)-O containing element M as a trace element, and a second crystalline secondary phase 22 with a main component being an oxide phase of (Nd, Pr, La)-O containing element M as a trace element. For the concentration of Sm, the first secondary phase 21 is higher than the second secondary phase 22, and for the concentration of element M, the second secondary phase 22 is higher than the first secondary phase 21. That is, in the rare earth sintered magnet 1, two main phases 10 and two secondary phases 20 exist, such that the concentration of Sm and the concentration of element M in the secondary phase 20 are different. Since Sm exists at a high concentration in the first subphase 21, it relatively facilitates the diffusion of Nd in the main phase 10, thereby improving the crystal magnetic anisotropy of the main phase 10. Furthermore, since Sm also exists within the grains of the main phase 10, it binds in the same magnetization direction as Fe, which is a ferromagnetic material, thus contributing to the improvement of remanent magnetic flux density. Element M exists at a high concentration in the second subphase 22, thus forming a nonmagnetic phase that magnetically separates the main phases 10, contributing to the improvement of magnetic properties. Sm and element M exist at high concentrations in different subphases 20, thereby achieving a balanced improvement in remanent magnetic flux density and coercivity. In this way, a rare-earth sintered magnet 1 can be provided that offers superior magnetic properties, such as temperature characteristics, compared to previous types.

[0088] Furthermore, by setting R to La and Sm, the main phase 10 becomes a mixture of a first main phase 11 (CNd > CPr) and a second main phase 12 (CNd < CPr). In other words, the rare-earth sintered magnet 1 contains two main phases 10, one with the first main phase 11 and the other with the second main phase 12. If we focus on the cores 11c and 12c of the two main phases 10, it is easy to generate a main phase 10 with two core-shell structures, where the concentration of Nd in the first main phase 11 is higher than the concentration of Pr, and conversely, the concentration of Pr in the second main phase 12 is higher than the concentration of Nd. As a result, the rare-earth sintered magnet 1 of Embodiment 2 can further improve the following effects: it does not use heavy rare-earth elements and suppresses the use of Nd, and improves magnetic properties, exhibiting superior magnetization compared to the past.

[0089] Implementation method 3.

[0090] In Embodiment 3, the method for manufacturing the rare earth sintered magnet 1 described in Embodiments 1 and 2 is divided into a method for manufacturing a rare earth sintered magnet alloy that serves as the raw material for the rare earth sintered magnet 1 and a method for manufacturing a rare earth sintered magnet 1 using a rare earth sintered magnet alloy.

[0091] Figure 4This is a flowchart illustrating an example of the steps in a method for manufacturing a rare-earth sintered magnet alloy according to Embodiment 3. Figure 4 As shown, the method for manufacturing a rare earth sintered magnet alloy, which serves as the raw material for the rare earth sintered magnet 1, includes: a melting process (step S1) in which the raw material of the rare earth sintered magnet alloy, containing elements constituting the rare earth sintered magnet 1, is heated to a temperature of 1000 K or higher to melt it; a first cooling process (step S2) in which the molten raw material is cooled on a rotating body to obtain a solidified alloy; and a second cooling process (step S3) in which the solidified alloy is further cooled in a container. Thus, a rare earth sintered magnet alloy can be manufactured. Each step will be described below.

[0092] In the melting process of step S1, the raw material of the rare earth sintered magnet alloy is heated to a temperature of 1000 K or higher in a crucible to melt it in an atmosphere containing an inert gas such as Ar (argon). This produces a melted alloy of the rare earth sintered magnet alloy. As raw materials, Nd, Pr, R, Fe, B, and M can be used. In the case of manufacturing the rare earth sintered magnet 1 of Embodiment 2, R is La and Sm. As M, one or more elements selected from Ga, Al, Cu, and Co can be listed. Alternatively, FeB can be used instead of B as a raw material.

[0093] Secondly, in the first cooling step of step S2, the molten alloy prepared in the melting step is poured into a tundish, and then poured onto a single roller, which serves as a rotating body. This rapidly cools the molten alloy on the single roller rotating in a predetermined direction, producing a solidified alloy with a thickness thinner than the ingot alloy. While a single roller is used as the rotating body, it is not limited to this; the molten alloy can also be rapidly cooled by contact with a double roller, a rotating disk, or a rotating cylindrical mold. From the viewpoint of efficiently obtaining a thin solidified alloy, the cooling rate in the first cooling step is preferably set to 10°C / second or more. 7 Below ℃ / second, a setting of 10 is preferred. 3 ℃ / second or higher and 10 4 Below ℃ / second. The thickness of the solidified alloy is in the range of 0.03 mm to 10 mm. The alloy melt begins to solidify from the part in contact with the single roller, and crystals grow in columnar or needle-like shapes in the thickness direction from the contact surface with the single roller.

[0094] Then, in the second cooling step of step S3, the thin solidified alloy prepared in the first cooling step is placed in a tray container for cooling. When the thin solidified alloy is placed in the tray container, it is pulverized and cooled into a flake-like rare earth sintered magnet alloy. Depending on the cooling rate, sometimes a ribbon-like rare earth sintered magnet alloy is also obtained, and it is not limited to a flake-like shape. From the viewpoint of obtaining a rare earth sintered magnet alloy with a microstructure exhibiting good temperature characteristics and magnetic properties, the cooling rate in the second cooling step is preferably set to 10. -2 ℃ / second or higher and 10 5 Below ℃ / second, a setting of 10 is preferred. -1 ℃ / second or higher and 10 2 Below ℃ / second.

[0095] The rare earth sintered magnet alloy obtained through these processes has a short axis dimension of 3 μm or more and 10 μm or less, and a long axis dimension of 10 μm or more and 300 μm or less. In Embodiment 2, the rare earth sintered magnet alloy has a fine crystalline structure containing a (Nd, Pr, La, Sm)-Fe-B crystalline phase containing element M as a trace component and a crystalline secondary phase 20 of oxides containing (Nd, Pr, La, Sm)-O containing element M as a trace component. The (Nd, Pr, La, Sm)-Fe-B crystalline phase containing element M as a trace component is also referred to as the (Nd, Pr, La, Sm)-Fe-B crystalline phase, and the crystalline secondary phase 20 of oxides containing (Nd, Pr, La, Sm)-O containing element M as a trace component is also referred to as the (Nd, Pr, La, Sm)-O phase. The (Nd, Pr, La, Sm)-O phase is a non-magnetic phase composed of oxides with a relatively high concentration of rare earth elements. The thickness of the (Nd, Pr, La, Sm)-O phase is equivalent to the width of the grain boundaries, and is less than 10 μm. Rare earth sintered magnet alloys manufactured using the above method exhibit a finer microstructure compared to rare earth sintered magnet alloys obtained by mold casting due to the rapid cooling process.

[0096] Secondly, the manufacturing method of rare earth sintered magnet 1 using rare earth sintered magnet alloy will be described. Figure 5 This is a flowchart illustrating an example of the steps in a method for manufacturing a rare-earth sintered magnet according to Embodiment 3. (See flowchart for example.) Figure 5As shown, the manufacturing method of rare earth sintered magnet 1 includes: a pulverizing step (step S21) of pulverizing a rare earth sintered magnet alloy having (Nd, Pr, La, Sm)-Fe-B crystal phase and (Nd, Pr, La, Sm)-O phase; a molding step (step S22) of preparing a molded body by molding the pulverized rare earth sintered magnet alloy powder; a sintering step (step S23) of sintering the molded body at a specified temperature, i.e., a sintering temperature, to obtain a sintered body; an aging step (step S24) of aging the sintered body to improve the magnetic properties such as coercivity of the rare earth sintered magnet 1; and a cooling step (step S25) of cooling the aging sintered body. Each step will be described below.

[0097] In the crushing process of step S21, the powder will be crushed according to... Figure 4 The method for manufacturing rare earth sintered magnet alloys produces rare earth sintered magnet alloy powder having (Nd, Pr, La, Sm)-Fe-B and (Nd, Pr, La, Sm)-O phases. The powder is pulverized to obtain rare earth sintered magnet alloy powder with a particle size of 200 μm or less, preferably 0.5 μm or more and 100 μm or less, and further approximately 1 μm or more and 10 μm or less, taking into account magnetic properties. In one example, the pulverization of the rare earth sintered magnet alloy is carried out using an agate mortar, a crusher, a jaw crusher, or a jet mill. In particular, when reducing the particle size of the powder, it is preferable to pulverize the rare earth sintered magnet alloy in an atmosphere containing an inert gas. By pulverizing the rare earth sintered magnet alloy in an atmosphere containing an inert gas, the incorporation of oxygen into the powder can be suppressed. However, if the atmosphere during pulverization does not affect the magnetic properties of the magnet, the pulverization of the rare earth sintered magnet alloy can be carried out in the atmosphere. It should be noted that when manufacturing the rare earth sintered magnet 1 of Embodiment 1, it is possible to make the La and Sm of the rare earth sintered magnet alloy used in manufacturing the rare earth sintered magnet 1 of Embodiment 2 into rare earth elements R other than Nd and Pr. That is, it is only necessary to crush the rare earth sintered magnet alloy having the (Nd,Pr,R)-Fe-B crystal phase and the (Nd,Pr,R)-O phase.

[0098] In step S22, the rare earth sintered magnetic alloy powder is compressed and molded in a mold under an applied magnetic field to prepare a molded body. In one example, the applied magnetic field can be set to 2T. It should be noted that the molding process can be performed without an applied magnetic field, not in one.

[0099] In the sintering process of step S23, a sintered body is obtained by holding the compressed molded body at a sintering temperature within the range of 950°C to 1300°C, preferably 1000°C to 1150°C, for a time within the range of 0.1 hours to 10 hours, preferably 1.0 hour to 6.0 hours. For sintering, to suppress oxidation, it is preferable to perform the sintering in an atmosphere containing inert gases or in a vacuum. Sintering can be performed while a magnetic field is applied.

[0100] Regarding the aging process in step S24, in Figure 5 In this case, the aging process includes the first aging step in step S24-1, the second aging step in step S24-2, the third aging step in step S24-3, and the fourth aging step in step S24-4. Regarding aging, to suppress oxidation, it is preferable to carry out the process in an atmosphere containing inert gases or in a vacuum.

[0101] In the first aging process of step S24-1, the obtained sintered body is kept at a temperature below the sintering temperature, i.e. the first aging temperature, specifically between 700°C and 950°C, for a period of 0.1 hours to 10 hours, preferably between 0.5 hours and 5 hours.

[0102] In the second aging process of step S24-2, after the first aging process, the sintered body held in the first aging process is held at a temperature less than the first aging temperature, i.e., the second aging temperature, specifically at a temperature of 450°C or higher but less than 700°C, for a period of 0.1 hours or more but less than 10 hours, preferably 1.0 hours or more but less than 7 hours.

[0103] In the third aging process of step S24-3, after the second aging process, the sintered body held in the second aging process is heated again to the first aging temperature, specifically a temperature in the range of 700°C or higher and less than 950°C, and held at the first aging temperature for 0.1 hours or more and 10 hours or less, preferably 0.5 hours or more and 5 hours or less.

[0104] In the fourth aging process of step S24-4, after the third aging process, the sintered body that was maintained in the third aging process is again maintained at the second aging temperature, specifically at a range of 450°C or higher and less than 700°C, for a range of 0.1 hours or more and 10 hours or less, preferably 1.0 hours or more and 7 hours or less.

[0105] Finally, in the cooling process of step S25, the sintered body held in the fourth aging process is held at a temperature lower than the second aging temperature, specifically between 200°C and 450°C, for 0.1 hours and 5 hours. Then, by cooling to room temperature, the rare earth sintered magnet 1 is completed. To suppress oxidation, cooling is preferably carried out in an atmosphere containing inactive gases or in a vacuum.

[0106] As described above, by controlling the temperature and time in the sintering, aging, and cooling processes, the sintered body is repeatedly maintained within a temperature range of unstable energy states. As a result, a first principal phase 11 containing CNd > CPr and a second principal phase 12 containing CNd < CPr can be mixed. In other words, the rare-earth sintered magnet 1 contains both the first principal phase 11 and the second principal phase 12. If the core portions 11c and 12c of the two principal phases 10 are considered, a rare-earth sintered magnet 1 with the following characteristics can be manufactured: the Nd concentration of the first principal phase 11 is higher than the Pr concentration, and conversely, the Pr concentration of the second principal phase 12 is higher than the Nd concentration.

[0107] Furthermore, a rare-earth sintered magnet 1 can be manufactured, which, in addition to the first main phase 11 and the second main phase 12 in Embodiment 1, also has a crystalline first secondary phase 21 with an oxide phase of (Nd, Pr, La, Sm)-O containing element M as a trace component as the main component, and a crystalline second secondary phase 22 with an oxide phase of (Nd, Pr, La)-O containing element M as a trace component as the main component. For the concentration of Sm, the first secondary phase 21 is higher than the second secondary phase 22, and for the concentration of element M, the second secondary phase 22 is higher than the first secondary phase 21. That is, in the aging process and the cooling process, the (Nd, Pr, La, Sm)-O phase, in one example, generates a crystalline first secondary phase 21 with an oxide phase of (Nd, Pr, La, Sm)-O as the main component and a crystalline second secondary phase 22 with an oxide phase of (Nd, Pr, La)-O as the main component, depending on the concentration of element M. It should be noted that the second subphase 22 may contain trace amounts of Sm. Furthermore, the concentration of Sm in the first subphase 21 is higher than that in the second subphase 22; therefore, it can also be said that the first subphase 21 forms an Sm-enriched section within the subphase 20. Additionally, the first subphase 21 sometimes contains a high-concentration section 41 with a high Sm concentration and a low-concentration section 42 with a low Sm concentration; therefore, in this case, it can also be said that the high-concentration section 41 of the first subphase 21 forms an Sm-enriched section.

[0108] Thus, a rare earth sintered magnet 1 can be provided that does not use heavy rare earth elements, suppresses the use of Nd, and has superior magnetic properties and magnetic characteristics compared to the past.

[0109] In Embodiment 3, rare earth sintered magnet alloy powder, which contains (Nd, Pr, La, Sm)-Fe-B and (Nd, Pr, La, Sm)-O phases, is formed. The formed body is then sintered to form a sintered body, which is subsequently aged to manufacture rare earth sintered magnet 1. Thus, the rare earth sintered magnet 1 according to Embodiment 2 can be manufactured.

[0110] Furthermore, in Embodiment 3, the temperature and time in the sintering, aging, and cooling processes are controlled. In one example, in the first aging process, the resulting sintered body is held at a temperature below the sintering temperature, specifically at a temperature between 700°C and 950°C, for 0.1 hours to 10 hours, preferably 0.5 hours to 5 hours. In the second aging process, the sintered body is held at a temperature below the first aging temperature, specifically at a temperature between 450°C and 700°C, for 0.1 hours to 10 hours, preferably 1.0 hour to 7 hours. In the third aging process, the temperature is raised again to the first aging temperature, specifically at a temperature between 700°C and 950°C, and the sintered body is held at the first aging temperature for 0.1 hours to 10 hours, preferably 0.5 hours to 5 hours. In the fourth aging process, the sintered body is held again at the second aging temperature, specifically between 450°C and 700°C, for 0.1 hours to 10 hours, preferably 1.0 hour to 7 hours. This controls the temperature and time so that the first and second aging processes are performed in two sets. This results in the sintered body being held in an unstable energy state at various temperature ranges. As a result, a rare-earth sintered magnet 1 containing a first main phase 11 (CNd > CPr) and a second main phase 12 (CNd < CPr) can be obtained. In other words, the rare-earth sintered magnet 1 contains two main phases 10: the first main phase 11 and the second main phase 12. By focusing on the cores 11c and 12c of the two main phases 10, it is possible to selectively produce a rare-earth sintered magnet 1 where the Nd concentration of the first main phase 11 is higher than the Pr concentration, and conversely, where the Pr concentration of the second main phase 12 is higher than the Nd concentration.

[0111] Furthermore, by employing the aforementioned manufacturing process, a rare-earth sintered magnet 1 can be selectively manufactured, possessing the following characteristic microstructure: a crystalline first secondary phase 21 with a (Nd, Pr, La, Sm)-O oxide phase containing trace amounts of element M as its main component, and a crystalline second secondary phase 22 with a (Nd, Pr, La)-O oxide phase containing trace amounts of element M as its main component. The first secondary phase 21 has a higher Sm concentration than the second secondary phase 22, while the second secondary phase 22 has a higher M concentration than the first secondary phase 21. Additionally, in the secondary phase 20, the Sm concentration in the first secondary phase 21 is higher than that in the second secondary phase 22. Therefore, a rare-earth sintered magnet 1 with the following characteristic microstructure can be manufactured: a first secondary phase 21 with an Sm-enriched portion, i.e., an Sm-enriched portion. Alternatively, if the first subphase 21 contains a high-concentration portion 41 with a high concentration of Sm and a low-concentration portion 42 with a low concentration of Sm, a rare earth sintered magnet 1 with the following characteristic microstructure can be manufactured: having a high-concentration portion 41 as an Sm enrichment portion.

[0112] Implementation method 4.

[0113] In Embodiment 4, a rotor using the rare earth sintered magnet 1 of Embodiment 1 or Embodiment 2 manufactured by the manufacturing method of Embodiment 3 will be described. Figure 6 A cross-sectional view is shown schematically, illustrating an example of the configuration of a rotor equipped with a rare-earth sintered magnet according to Embodiment 4. Figure 6 The image shows a cross-section in a direction perpendicular to the rotation axis RA of the rotor 100.

[0114] The rotor 100 is capable of rotating about the rotation axis RA. The rotor 100 includes a rotor core 101 and rare-earth sintered magnets 1 inserted into magnet insertion holes 102 disposed along the circumference of the rotor 100 in the rotor core 101. Figure 6 The diagram shows an example where four magnet insertion holes 102 are provided in the rotor core 101, and four rare-earth sintered magnets 1 are inserted into the magnet insertion holes 102. The number of magnet insertion holes 102 and rare-earth sintered magnets 1 can be changed according to the design of the rotor 100. As for the rotor core 101, it is formed by stacking multiple disc-shaped electromagnetic steel plates in the axial direction of the rotation shaft RA.

[0115] The rare earth sintered magnet 1 is manufactured according to the manufacturing method described in Embodiment 3. Four rare earth sintered magnets 1 are inserted into corresponding magnet insertion holes 102. The four rare earth sintered magnets 1 are magnetized in different ways between adjacent rare earth sintered magnets 1 with the magnetic poles of the rare earth sintered magnets 1 on the radially outer side of the rotor 100.

[0116] The rotor 100 according to Embodiment 4 includes a rare-earth sintered magnet 1 according to Embodiment 1 or Embodiment 2, which can achieve improved magnetic properties at room temperature and suppress the decrease in magnetic properties associated with temperature rise. As described above, the rare-earth sintered magnet 1 according to Embodiment 1 or Embodiment 2, being a rare-earth sintered magnet 1 capable of maintaining high remanent magnetic flux density and coercivity and suppressing the decrease in magnetic properties associated with temperature rise, also suppresses the decrease in magnetic properties even in high-temperature environments exceeding 100°C. As a result, it is possible to replace Nd with inexpensive rare-earth elements instead of using expensive, geographically uneven, and risky heavy rare-earth elements, thereby improving magnetic properties and magnetization, and stabilizing the operation of the rotor 100 even in high-temperature environments exceeding 100°C. Furthermore, the rare-earth sintered magnet 1 according to Embodiment 1 or Embodiment 2 has superior magnetization performance compared to the conventional method, thus enabling magnetization even when the rare-earth sintered magnet 1 is installed in the rotor 100 assembly state, thereby simplifying the manufacturing process. Furthermore, it enables a magnetization process that suppresses voltage, thus contributing to energy conservation.

[0117] Implementation method 5.

[0118] In Embodiment 5, a rotating machine equipped with the rotor 100 of Embodiment 4 will be described. Figure 7 A cross-sectional view is shown schematically as an example of the configuration of the rotating machine according to Embodiment 5. Figure 7 The image shows a cross-section in a direction perpendicular to the rotation axis RA of the rotor 100.

[0119] The rotating machine 120 includes: a rotor 100, as described in Embodiment 4, capable of rotating around a rotation axis RA; and an annular stator 130 coaxially disposed with respect to the rotor 100. The stator 130 is formed by stacking multiple electromagnetic steel plates in the axial direction of the rotation axis RA. The configuration of the stator 130 is not limited to this, and existing configurations can also be used. Regarding the stator 130, teeth 131 protruding toward the rotor 100 are provided along the inner surface of the stator 130. A winding 132 is provided in the teeth 131. Regarding the winding method of the winding 132, in one example, it can be concentrated winding or distributed winding. That is, regarding the stator 130, the winding 132 provided by the teeth 131 protruding toward the rotor 100 is located on the inner surface of the side where the rotor 100 is disposed, and it has an annular structure arranged opposite to the rotor 100. It is sufficient that the rotor 100 located in the rotating machine 120 has two or more magnetic poles, that is, there are two or more rare earth sintered magnets 1. Additionally, in Figure 7 The example shown is a rotor 100 with an embedded magnet, but it can also be a rotor 100 with a surface magnet in which a rare earth sintered magnet 1 is fixed to the outer periphery with an adhesive.

[0120] The rotating machine 120 of Embodiment 5 includes a rare-earth sintered magnet 1 according to Embodiment 1 or Embodiment 2, which is capable of improving magnetic properties at room temperature and suppressing the decrease in magnetic properties associated with temperature rise. As described above, the rare-earth sintered magnet 1 according to Embodiment 1 or Embodiment 2 is a rare-earth sintered magnet 1 capable of maintaining high remanent magnetic flux density and coercivity, and suppressing the decrease in magnetic properties associated with temperature rise. Therefore, the decrease in magnetic properties is also suppressed in high-temperature environments such as those exceeding 100°C. As a result, it is possible to replace Nd with inexpensive rare-earth elements instead of using expensive, geographically uneven, and risky heavy rare-earth elements, thereby improving magnetic properties and magnetization, and enabling stable driving of the rotor 100 even in high-temperature environments such as those exceeding 100°C, thus stabilizing the operation of the rotating machine 120.

[0121] Example

[0122] The following examples and comparative examples will be used to describe in detail the rare earth sintered magnet 1 of this disclosure.

[0123] In Examples 1 to 8, rare earth sintered magnets 1 were manufactured using samples of (Nd, Pr, La, Sm)-Fe-B crystal phases and (Nd, Pr, La, Sm)-O phases containing element M as trace elements, with different compositions of various rare earth sintered magnet alloys. The method described in Example 3 was used to manufacture rare earth sintered magnets 1. In Examples 1 to 8, rare earth sintered magnets 1 were manufactured using rare earth sintered magnet alloys with varying contents of Nd, Pr, La, and Sm. Specifically, in Examples 1 to 8, rare earth sintered magnets 1 were manufactured using rare earth sintered magnet alloys containing (Nd, Pr, La, Sm)-Fe-B crystal phases and (Nd, Pr, La, Sm)-O phases containing element M as trace elements, using the manufacturing method described in Example 3. M is one or more elements selected from Ga, Al, Cu, and Co; the case where M is Co is given as an example.

[0124] In Comparative Examples 1 to 14, rare earth sintered magnets 1 were experimentally manufactured using samples of multiple rare earth sintered magnet alloys R-Fe-BM with different compositions, employing the general rare earth magnet manufacturing method shown in Patent Document 1 or Patent Document 2. In the rare earth sintered magnet 1 samples according to Comparative Examples 1 to 14, the portion of R was modified.

[0125] In Comparative Examples 1 to 7, a rare earth sintered magnet 1 was manufactured using a rare earth sintered magnet alloy in which R contains Nd, a heavy rare earth element Dy, or any one of Pr, La, and Sm, and M contains one or more elements selected from Ga, Al, Cu, and Co, and the manufacturing method shown in Patent Document 1 was employed. Here, the case where M is Co is cited as an example. However, in Comparative Example 1, an Nd-Fe-BM containing no rare earth element R other than Nd was manufactured, and in Comparative Example 2, an Nd-Fe-B containing no rare earth element R other than Nd and element M was manufactured.

[0126] In Comparative Examples 8 to 14, a rare earth sintered magnet 1 was manufactured using a rare earth sintered magnet alloy in which R contains Nd, the heavy rare earth element Dy, or any one of Pr, La, and Sm, and M contains one or more elements selected from Ga, Al, Cu, and Co, using the manufacturing method shown in Patent Document 2. Here, the case where M is Co is cited as an example. However, in Comparative Example 8, an Nd-Fe-BM containing no rare earth element R other than Nd was manufactured, and in Comparative Example 9, an Nd-Fe-B containing no rare earth element R other than Nd and element M was manufactured. The manufacturing method shown in Patent Document 2 includes a step of heat-processing the sintered body.

[0127] Table 3 shows the general formula, the content of elements constituting R, the analysis results of microstructure, and the determination results of magnetic properties and magnetic charge properties of rare earth sintered magnets according to the examples and comparative examples. In Table 3, the general formula of the main phase 10 of the rare earth sintered magnets 1 of Examples 1 to 8 and Comparative Examples 1 to 14 is shown.

[0128] [Table 3]

[0129]

[0130] Next, the method for analyzing the microstructure of the rare earth sintered magnets 1 of Examples 1 to 8 and Comparative Examples 1 to 14 will be described. The microstructure of the rare earth sintered magnets 1 was determined by elemental analysis using a scanning electron microscope (SEM) and EPMA. FE-EPMA (manufactured by Nippon Electron Ltd., product name: JXA-8530F) was used for both SEM and EPMA. The accelerating voltage was 15.0 kV and the irradiation current was 2.271 eΩ. -008 A, the illumination time is 130ms, the number of pixels is 512 pixels × 512 pixels, the magnification is 5000 times, and the cumulative number of times is 1.

[0131] Next, the evaluation method for the magnetic properties of the rare earth sintered magnets 1 of Examples 1 to 8 and Comparative Examples 1 to 14 will be described. The evaluation of magnetic properties was performed by measuring the coercivity of multiple samples using a pulse-excited BH-Tracer. The maximum applied magnetic field obtained using the BH-Tracer was 6T or more, which required the rare earth sintered magnet 1 to be fully magnetized. Besides the pulse-excited BH-Tracer, any device capable of generating a maximum applied magnetic field of 6T or more, such as a DC automatic recording fluxmeter (also called a DC-type BH-Tracer), a vibrating sample magnetometer (VSM), a magnetic property measurement system (MPMS), or a physical property measurement system (PPMS), can be used. The measurement was performed in an atmosphere containing inert gases such as nitrogen. The magnetic properties of each sample were measured by detecting the magnetization picked up by a probe coil or magnetic sensor from the rare earth sintered magnet 1 magnetized using an applied magnetic field. The magnetic properties were determined from the measured hysteresis, i.e., the JH curve or BH curve. Furthermore, the magnetic properties of each sample were measured at various temperatures, specifically a first measurement temperature T1 and a second measurement temperature T2. The temperature coefficient α [% / ℃] of the remanent magnetic flux density was calculated by dividing the ratio of the difference between the remanent magnetic flux density at the first measurement temperature T1 and the remanent magnetic flux density at the second measurement temperature T2 to the remanent magnetic flux density at the first measurement temperature T1 by the temperature difference (T2-T1). Similarly, the temperature coefficient β [% / ℃] of the coercivity was calculated by dividing the ratio of the difference between the coercivity at the first measurement temperature T1 and the coercivity at the second measurement temperature T2 to the coercivity at the first measurement temperature T1 by the temperature difference (T2-T1). Therefore, the smaller the absolute values ​​of the temperature coefficients of the magnetic properties, |α| and |β|, the more effectively the decrease in the magnetic properties of the magnet associated with an increase in temperature is suppressed.

[0132] Furthermore, the magnetization performance is determined by calculating the magnetization ratio from the ratio of the magnetic flux density measured using hysteresis applied under a given magnetic permeability and the magnetic flux density measured using hysteresis applied under a saturated magnetic field. If a high magnetization ratio is obtained even in a lower magnetic field, the magnetization performance can be considered high.

[0133] First, the analytical results of each sample according to Examples 1 to 8 and Comparative Examples 1 to 14 will be explained. Figure 8 This is a diagram showing the compositional image obtained by analyzing the cross-section of rare earth sintered magnets according to Examples 1 to 8 using FE-EPMA. Figures 9 to 14 The elemental mapping is obtained by analyzing the cross-sections of rare earth sintered magnets according to Examples 1 to 8 using FE-EPMA. Figure 9 For the element mapping of Nd, Figure 10 For the element mapping of Pr, Figure 11 For element mapping of Co, Figure 12 A mapping of elements to O. Figure 13 For the element mapping of La, Figure 14 This is an element mapping for Sm. It should be noted that... Figures 9 to 14 To Figure 8 The diagram shows the elemental mapping of the region. Furthermore, all rare-earth sintered magnets 1 according to Examples 1 to 8 show the same results, therefore... Figures 8 to 14 Representative embodiments from Examples 1 to 8 are shown below. Furthermore, regarding... Figure 1 and Figure 2 The same constituent elements are labeled with the same reference numerals in the accompanying drawings.

[0134] like Figure 9 and Figure 10 As shown, in each of the samples in Examples 1 to 8, the rare earth sintered magnet 1, in which R is one or more rare earth elements selected from Nd and Pr and satisfies the general formula (Nd, Pr, R)-Fe-BM, contains Nd2Fe. 14 In the main phase 10 of the B-based crystal structure, there exists a main phase 10 having core portions 11c and 12c and shell portions 11s and 12s covering the core portions 11c and 12c. In addition, it can be confirmed that in the main phase 10, a first main phase 11 with CNd > CPr and a second main phase 12 with CNd < CPr are mixed.

[0135] The concentration difference shown in "first principal phase 11 (CNd > CPr) and second principal phase 12 (CNd < CPr)" indicates a clear difference between the detection intensities of Nd and Pr, achieved through EPMA mapping analysis. Specifically, in the case of first principal phase 11, the EPMA detection intensity is higher than average for Nd concentration in the core 11c, and lower than average for Pr concentration, indicating a near-lower limit. Second principal phase 12 is essentially the opposite of first principal phase 11.

[0136] More specifically, with Figure 9 The mapping of Nd and Figure 10 Taking the Pr mapping as an example, the average detection level of Nd by EPMA is 32.0, and the average detection level of Pr is 45. In the case of the first main phase 11, CNd is higher than 32.0, and CPr is near the lower limit, indicating a clear concentration difference. Furthermore, the second main phase 12 is the opposite of the first main phase 11, therefore CPr is higher than 45, and CNd is near the lower limit, again indicating a clear concentration difference.

[0137] like Figures 11 to 14 As shown, when R = La, Sm, the rare earth sintered magnet 1, in addition to the first main phase 11 and the second main phase 12 in Embodiment 1, has a crystalline first secondary phase 21 with an oxide phase represented as (Nd, Pr, La, Sm)-O containing element M as a trace component as the main component, and a crystalline second secondary phase 22 with an oxide phase represented as (Nd, Pr, La)-O containing element M as a trace component as the main component. Furthermore, it can be confirmed that the first secondary phase 21 has a higher concentration of Sm than the second secondary phase 22, and the second secondary phase 22 has a higher concentration of Co, which is element M, than the first secondary phase 21.

[0138] In Table 3, for samples where the states of the first main phase 11 (CNd > CPr) and the second main phase 12 (CNd < CPr) can be confirmed, enter "〇" in the columns for the first main phase 11 and the second main phase 12, respectively. For samples that cannot be confirmed, enter "×" in the columns for the first main phase 11 and the second main phase 12, respectively. A concentration difference with an inequality sign indicates a clear difference in the detection intensity of Nd and Pr. Specifically, in one example, in the case of the first main phase 11, the detection intensity of EPMA is higher than average for Nd concentration, while the detection intensity of EPMA is near the lower limit for Pr concentration. In the case of the second main phase 12, the situation is the opposite of the first main phase 11. If only CNd < CPr is confirmed as in the second main phase 12, enter "〇" in the column for the second main phase 12 and "×" in the column for the first main phase 11.

[0139] Additionally, in Table 3, for samples that can be identified as having a first secondary phase 21 with a crystalline structure mainly composed of an oxide phase (Nd, Pr, La, Sm)-O containing element M as a trace component, and a second secondary phase 22 with a crystalline structure mainly composed of an oxide phase (Nd, Pr, La)-O containing element M as a trace component, and where the concentration of element M in the second secondary phase 22 is higher than that in the first secondary phase 21, enter "〇" in the "M Concentration First Secondary Phase < Second Secondary Phase" column under the "Secondary Phase" section of the "Meat Structure" item. For samples that cannot be identified, enter "×" in the "M Concentration First Secondary Phase < Second Secondary Phase" column under the "Secondary Phase" section of the "Meat Structure" item. Furthermore, for samples that have only one secondary phase 20 or no Sm concentration difference between secondary phases 20, enter "×" in the "M Concentration First Secondary Phase < Secondary Phase" column under the "Secondary Phase" section of the "Meat Structure" item.

[0140] It should be noted that the concentration difference of Sm between the first subphase 21 and the second subphase 22 means that, using EPMA mapping analysis, the average detection intensity of Sm in the first subphase 21 is higher than that in the second subphase 22. Specifically, with Figure 14Taking the Sm mapping as an example, the average detection level of Sm by EPMA is 5.4, while the first subphase 21 is higher than 5.4 and the second subphase 22 is lower than 5.4, meaning that it is a state that could not be detected in the condensed state. Furthermore, the concentration difference of Co as element M between the first subphase 21 and the second subphase 22 means that, using the mapping analysis of EPMA, the average detection intensity of Co is higher in the second subphase 22 compared to the first subphase 21. Specifically, taking... Figure 11 Taking the Co mapping as an example, the average detection level of Co in EPMA is 5.4, while the second subphase 22 is higher than 5.4 and the first subphase 21 is lower than 5.4, that is, the state that could not be detected in the condensed state.

[0141] Furthermore, the intensity ratios of elemental mappings obtained from FE-EPMA analysis confirm that the number of first principal phases 11, where CNd > CPr, is greater than the number of second principal phases 12, where CNd < CPr. Focusing on the shell portions 11s and 12s of the core-shell structure, it is also confirmed that the first principal phase 11 satisfies the relationship CNd > SNd and CPr < SPr, while the second principal phase 12 satisfies the relationship CNd < SNd and CPr > SPr.

[0142] Next, the results of the magnetic property measurements of each sample according to Examples 1 to 8 and Comparative Examples 1 to 14 will be explained. Each sample for magnetic measurement was a block shape with a length, width, and height of 7 mm. The first measurement temperature T1 was 23°C, and the second measurement temperature T2 was 200°C. 23°C is room temperature. The second measurement temperature T2 of 200°C is a temperature that can be generated in the environment during the operation of automotive motors and industrial motors.

[0143] First, the remanent magnetic flux density and coercivity of each sample from Examples 1 to 8 and Comparative Examples 2 to 14 were determined in comparison with Comparative Example 1. The remanent magnetic flux density and coercivity values ​​of each sample at 23°C were determined to be "equivalent" if they showed values ​​within 1% of the measurement error compared to those in Comparative Example 1, "good" if they showed values ​​higher than 1%, and "poor" if they showed values ​​lower than 1%.

[0144] Secondly, the temperature coefficient α of the remanent magnetic flux density was calculated using the remanent magnetic flux density at 23°C of the first measurement temperature T1 and the remanent magnetic flux density at 200°C of the second measurement temperature T2. Similarly, the temperature coefficient β of the coercivity was calculated using the coercivity at 23°C of the first measurement temperature T1 and the coercivity at 200°C of the second measurement temperature T2. The temperature coefficients of the remanent magnetic flux density and the temperature coefficients of the coercivity of each sample from Examples 1 to 8 and Comparative Examples 2 to 14 were compared with those from Comparative Example 1. For each sample, compared with the absolute values ​​of the temperature coefficients of the remanent magnetic flux density |α| and the absolute values ​​of the temperature coefficients of the coercivity |β| of the sample from Comparative Example 1, values ​​within ±1% of the measurement error were judged as "equivalent," values ​​lower than -1% were judged as "good," and values ​​higher than +1% were judged as "poor." For samples judged as "good", the decrease in magnetic properties associated with temperature rise is suppressed due to the smaller temperature coefficient, thus providing rare earth sintered magnets 1 with stable magnetic properties even at high temperatures.

[0145] Secondly, regarding magnetic properties, the magnetization rate is calculated by the ratio of the magnetic flux density (the intersection of the hysteresis and permeability Pc under an applied magnetic field of 20 kOe) to the magnetic flux density (the intersection of the hysteresis and permeability Pc under an applied magnetic field of 80 kOe under saturation magnetization). The magnetic properties of each sample from Examples 1 to 8 and Comparative Examples 2 to 14 are compared with those of Comparative Example 1. That is, for each sample, if the magnetization rate compared to that of the sample according to Comparative Example 1 shows a value greater than or equal to -1% of the measurement error, it is judged as "equivalent or better"; if the value shows a value lower than -1%, it is judged as "poor". For samples judged as "equivalent or better", a rare-earth sintered magnet 1 with high magnetic properties can be provided.

[0146] The results of the determination of the remanent magnetic flux density, coercivity, temperature coefficient of remanent magnetic flux density, temperature coefficient of coercivity, and magnetic properties are shown in Table 3.

[0147] Comparative Example 1 is a sample of a rare-earth sintered magnet 1 manufactured according to the manufacturing method described in Patent Document 1, using Nd, Fe, and FeB in an Nd-Fe-BM configuration, and further using Co as element M as a raw material. When observing the microstructure of this sample using the above method, since Pr, La, and Sm were not added, the core-shell structure in the main phase 10 could not be confirmed, nor could it be confirmed that the concentration of Sm in the secondary phase 20 was higher in the first secondary phase 21 than in the second secondary phase 22. Furthermore, when evaluating the magnetic properties of this sample using the above method, the remanent magnetic flux density B... r The coercivity is 1.32T, and the coercivity H is... cJThe remanent flux density is 1250 kA / m. The temperature coefficients of remanent flux density and coercivity are |α| = 0.191% / ℃ and |β| = 0.460% / ℃, respectively. Furthermore, the magnetization rate is 98.6%. These values ​​from Comparative Example 1 are used as a reference.

[0148] Comparative Example 2 is a sample of a rare earth sintered magnet 1 manufactured using Nd, Fe, and FeB as raw materials in an Nd-Fe-B configuration, according to the manufacturing method described in Patent Document 1. No Co, as element M, was added in Comparative Example 2. When observing the microstructure of this sample using the method described above, since Pr, La, and Sm were not added, the core-shell structure in the main phase 10 could not be confirmed, nor could it be confirmed that the concentration of Sm in the secondary phase 20 was higher in the first secondary phase 21 than in the second secondary phase 22. Since Co, as element M, was not present, it could not be confirmed that the concentration of Co in the second secondary phase 22 was higher than in the first secondary phase 21. The remanent magnetic flux density and coercivity were "poor," but the temperature coefficients of the remanent magnetic flux density and coercivity were "equal," and the magnetic properties were "equal or better."

[0149] Comparative Example 3 is a sample of a rare earth sintered magnet 1 manufactured according to the manufacturing method described in Patent Document 1, using Nd, Dy, Fe, and FeB in a (Nd, Dy)-Fe-BM configuration and Co as element M. When observing the microstructure of this sample using the above method, since Pr, La, and Sm were not added, the core-shell structure in the main phase 10 could not be confirmed, nor could it be confirmed that the concentration of Sm in the secondary phase 20 was higher in the first secondary phase 21 than in the second secondary phase 22. Furthermore, it could not be confirmed that the concentration of Co was higher in the second secondary phase 22 than in the first secondary phase 21. In addition, when evaluating the magnetic properties of this sample using the above method, the remanent magnetic flux density was "poor," the coercivity was "good," the temperature coefficient of the remanent magnetic flux density was "equal," the temperature coefficient of the coercivity was "equal," and the magnetic properties were "equal or better." This results in the following: due to the substitution of part of Nd with Dy, which has high crystal magnetic anisotropy, and the addition of Co as element M in the secondary phase 20, the coercivity is improved, but the residual magnetic flux density becomes undesirable because the structure control of the main phase 10 cannot be achieved.

[0150] Comparative Example 4 is a sample of a rare earth sintered magnet 1 manufactured according to the manufacturing method described in Patent Document 1, using Nd, Pr, Fe, and FeB in a (Nd, Pr)-Fe-BM configuration, and further using Co as element M as a raw material. When observing the microstructure of this sample using the above method, although the main phase 10, a mixture of Nd and Pr, could be confirmed due to the addition of Pr, a core-shell structure was not formed. Furthermore, since La and Sm were not added, it could not be confirmed that the concentration of Sm in the secondary phase 20 was higher in the first secondary phase 21 than in the second secondary phase 22. Similarly, it could not be confirmed that the concentration of Co in the second secondary phase 22 was higher than in the first secondary phase 21. When evaluating the magnetic properties of this sample using the above method, the remanent magnetic flux density was "equal," the coercivity was "good," the temperature coefficient of the remanent magnetic flux density was "equal," the temperature coefficient of the coercivity was "poor," and the magnetic properties were "equal or better." This results in the following: although the magnetic anisotropy and coercivity of the main phase 10 are increased due to the addition of Pr and Co, the residual magnetic flux density is the same and the temperature coefficient of coercivity is poor because the core-shell structure of the main phase 10 cannot be formed and the Co in the secondary phase 20 cannot be controlled.

[0151] Comparative Example 5 is a sample of a rare earth sintered magnet 1 manufactured according to the manufacturing method described in Patent Document 1, using Nd, La, Sm, Fe, and FeB in a (Nd, La, Sm)-Fe-BM configuration, and further using Co as element M as a raw material. When observing the microstructure of this sample using the above method, the core-shell structure of the main phase 10 could not be confirmed because Pr was not added. Furthermore, although the concentration of Sm segregated in a secondary phase 20 due to the addition of La and Sm, a second secondary phase 22 was not present. Therefore, it could not be confirmed that the first secondary phase 21 had a higher concentration of Sm than the second secondary phase 22, nor could it be confirmed that the second secondary phase 22 had a higher concentration of Co than the first secondary phase 21. Additionally, when evaluating the magnetic properties of this sample using the above method, the remanent magnetic flux density was "equal," the coercivity was "equal," the temperature coefficient of the remanent magnetic flux density was "good," the temperature coefficient of the coercivity was "good," and the magnetic charging performance was "equal or better." This results in the following: although the temperature coefficient of magnetic properties shows good results due to the presence of La and Sm in the principal phase 10 or the secondary phase 20, the organization control of the principal phase 10 and the secondary phase 20 cannot be performed due to the absence of Pr, and the remanent magnetic flux density and coercivity are equal.

[0152] Comparative Example 6 is a sample of a rare earth sintered magnet 1 manufactured according to the manufacturing method described in Patent Document 1, using Nd, La, Sm, Fe, and FeB in a (Nd, La, Sm)-Fe-BM configuration, and further using Co as element M as a raw material. The composition ratio of Nd, La, and Sm differs from that of Comparative Example 5. When observing the microstructure of this sample using the method described above, since Pr was not added, the core-shell structure of the main phase 10 could not be confirmed. Furthermore, although the concentration of Sm segregated in a secondary phase 20 due to the addition of La and Sm, a second secondary phase 22 was not present. Therefore, it could not be confirmed that the concentration of the first secondary phase 21 was higher than that of the second secondary phase 22 in terms of Sm concentration, nor could it be confirmed that the concentration of the second secondary phase 22 was higher than that of the first secondary phase 21 in terms of Co concentration. Furthermore, when evaluating the magnetic properties of the sample using the method described above, the remanent magnetic flux density was "equal," the coercivity was "equal," the temperature coefficient of the remanent magnetic flux density was "good," the temperature coefficient of the coercivity was "good," and the magnetic properties were "equal or better." This indicates that even with adjustments to the amounts of La and Sm added, since Pr was not added, the microstructure control of the main phase 10 and the secondary phase 20 could not be performed, and the remanent magnetic flux density and coercivity became equal. Thus, even with changes in the composition ratio of Nd, La, and Sm, approximately the same results as in Comparative Example 5 were obtained.

[0153] Comparative Example 7 is a sample of a rare-earth sintered magnet 1 manufactured according to the manufacturing method described in Patent Document 1, using Nd, Pr, La, Sm, Fe, and FeB in the form of (Nd, Pr, La, Sm)-Fe-BM, and further using Co as element M as a raw material. When observing the microstructure of this sample according to the above method, although a main phase 10 of Nd and Pr mixture can be identified due to the addition of Pr, a core-shell structure is not formed. In addition, although the concentration of Sm segregates into a secondary phase 20 due to the segregation of La, a second secondary phase 22 is not present. Furthermore, it cannot be confirmed that the concentration of the first secondary phase 21 is higher than that of the second secondary phase 22 in terms of Sm concentration, nor can it be confirmed that the concentration of the second secondary phase 22 is higher than that of the first secondary phase 21 in terms of Co concentration. Furthermore, when evaluating the magnetic properties of the sample according to the above method, the remanent magnetic flux density was "equivalent", the coercivity was "good", the temperature coefficient of the remanent magnetic flux density was "good", the temperature coefficient of the coercivity was "equivalent", and the magnetic properties were "equivalent or better". This resulted in the following: due to the addition of Pr in Comparative Example 6, the absolute value of the coercivity increased, but the microstructure control of the main phase 10 and the secondary phase 20 could not be achieved, and therefore the temperature coefficient of the coercivity deteriorated compared to the case of Comparative Example 6.

[0154] Comparative Example 8 is a sample of a rare earth sintered magnet 1 manufactured according to the manufacturing method described in Patent Document 2, which includes hot processing, using Nd, Fe, and FeB in an Nd-Fe-BM configuration and Co as element M. When observing the microstructure of this sample using the above method, since Pr, La, and Sm were not added, the core-shell structure in the main phase 10 could not be confirmed, nor could it be confirmed that the concentration of Sm in the secondary phase 20 was higher in the first secondary phase 21 than in the second secondary phase 22. Furthermore, it could not be confirmed that the concentration of Co in the second secondary phase 22 was higher than in the first secondary phase 21. However, the characteristic of magnets manufactured using hot processing, namely, the refinement of the microstructure, was confirmed. When evaluating the magnetic properties of this sample using the above method, the remanent magnetic flux density was "equal," the coercivity was "good," the temperature coefficient of the remanent magnetic flux density was "equal," the temperature coefficient of the coercivity was "equal," and the magnetization performance was "poor." This resulted in the following: although the coercivity was improved by making the grain boundaries nonmagnetic using element M, the microstructure control of the main phase 10 and the secondary phase 20 could not be achieved due to the lack of addition of Pr, La and Sm.

[0155] Comparative Example 9 is a sample of a rare earth sintered magnet 1 manufactured using Nd, Fe, and FeB as raw materials in an Nd-Fe-B manner, according to the manufacturing method described in Patent Document 2, which includes hot processing. In Comparative Example 9, Co, as element M, was not added. When observing the microstructure of this sample according to the above method, since Pr, La, and Sm were not added, the core-shell structure in the main phase 10 could not be confirmed, nor could it be confirmed that the concentration of Sm in the secondary phase 20 was higher in the first secondary phase 21 than in the second secondary phase 22. Furthermore, since Co was not added, it could not be confirmed that the concentration of Co in the second secondary phase 22 was higher than that in the first secondary phase 21. However, the characteristic of magnets manufactured by hot processing, namely, the fineness of the microstructure, was confirmed. When evaluating the magnetic properties of this sample according to the above method, the remanent magnetic flux density was "poor", the coercivity was "good", the temperature coefficient of the remanent magnetic flux density was "equal", the temperature coefficient of the coercivity was "equal", and the magnetic properties were "poor". This results in the following: as the magnetic powder becomes finer due to thermal processing, the coercivity increases, and the temperature coefficient of the residual magnetic flux density becomes equal to that of the coercivity. However, due to the difficulty in aligning the magnetic moments, the residual magnetic flux density decreases, and the magnetic properties deteriorate.

[0156] Comparative Example 10 is a sample of a rare earth sintered magnet 1 manufactured according to the manufacturing method described in Patent Document 2, which includes heat treatment, using Nd, Dy, Fe, and FeB in a (Nd, Dy)-Fe-BM configuration and Co as element M. When observing the microstructure of this sample using the above method, since Pr, La, and Sm were not added, the core-shell structure in the main phase 10 could not be confirmed, nor could it be confirmed that the concentration of Sm in the secondary phase 20 was higher in the first secondary phase 21 than in the second secondary phase 22. Furthermore, it could not be confirmed that the concentration of Co was higher in the second secondary phase 22 than in the first secondary phase 21. Additionally, when evaluating the magnetic properties of this sample using the above method, the remanent magnetic flux density was "poor," the coercivity was "good," the temperature coefficient of the remanent magnetic flux density was "equal," the temperature coefficient of the coercivity was "equal," and the magnetic properties were "poor." This resulted in the following: In addition to using thermal processing to refine the magnetic powder, the coercivity was greatly improved by replacing part of Nd with Dy, which has high crystalline magnetic anisotropy, and by adding element M. The temperature coefficient of the residual magnetic flux density was equal to that of the coercivity. However, the residual magnetic flux density decreased and the magnetic properties deteriorated because the magnetic moments were difficult to align.

[0157] Comparative Example 11 is a sample of a rare earth sintered magnet 1 manufactured according to the manufacturing method described in Patent Document 2, which includes hot processing, using Nd, Pr, Fe, and FeB in a (Nd, Pr)-Fe-BM configuration and Co as element M. When observing the microstructure of this sample using the above method, a core-shell structure was confirmed due to the addition of Pr and the hot processing; however, only the main phase 10 with a high Pr concentration in the core was confirmed to have a core-shell structure. Furthermore, since La and Sm were not added, it could not be confirmed that the first subphase 21 had a higher Sm concentration than the second subphase 22 in the subphase 20. Similarly, it could not be confirmed that the second subphase 22 had a higher Co concentration than the first subphase 21. When evaluating the magnetic properties of this sample using the above method, the remanent magnetic flux density was "poor," the coercivity was "good," the temperature coefficient of the remanent magnetic flux density was "equal," the temperature coefficient of the coercivity was "equal," and the magnetic properties were "poor." This resulted in the following: In addition to using thermal processing to refine the magnetic powder, the coercivity was significantly increased to the level of rare earth sintered magnet 1 with added Dy due to the formation of a core-shell structure with a high concentration of Pr in the core and the addition of Co. The temperature coefficient of the residual magnetic flux density and the temperature coefficient of the coercivity were equal, but the residual magnetic flux density decreased and the magnetic properties deteriorated due to the difficulty in aligning the magnetic moments.

[0158] Comparative Example 12 is a sample of a rare earth sintered magnet 1 manufactured according to the manufacturing method described in Patent Document 2, which includes hot processing, using Nd, La, Sm, Fe, and FeB in the form of (Nd, La, Sm)-Fe-BM and Co as element M. When observing the microstructure of this sample using the above method, since Pr was not added, the core-shell structure of the main phase 10 could not be confirmed. Furthermore, although the concentration of Sm segregated in one secondary phase 20 due to the addition of La and Sm, a second secondary phase 22 was not present. Therefore, it could not be confirmed that the first secondary phase 21 had a higher concentration of Sm than the second secondary phase 22, nor could it be confirmed that the second secondary phase 22 had a higher concentration of Co than the first secondary phase 21. Additionally, when evaluating the magnetic properties of this sample using the above method, the remanent magnetic flux density was "poor," the coercivity was "good," the temperature coefficient of the remanent magnetic flux density was "good," the temperature coefficient of the coercivity was "good," and the magnetic properties were "poor." This resulted in the following: In addition to the use of hot processing, the coercivity was significantly improved to the level of rare earth sintered magnet 1 with added Dy due to the addition of Co. Furthermore, La and Sm were present in the main phase 10 or the secondary phase 20, and the magnetic powder was miniaturized, resulting in good results for the temperature coefficient of residual magnetic flux density and the temperature coefficient of coercivity. However, due to the difficulty in aligning the magnetic moments, the residual magnetic flux density decreased, and the magnetic properties deteriorated.

[0159] Comparative Example 13 is a sample of a rare earth sintered magnet 1 manufactured according to the manufacturing method described in Patent Document 2, which includes heat treatment, using Nd, La, Sm, Fe, and FeB in the form of (Nd, La, Sm)-Fe-BM and Co as element M. The composition ratio of Nd, La, and Sm is different from that of Comparative Example 12. When observing the microstructure of this sample according to the above method, since Pr was not added, the core-shell structure of the main phase 10 could not be confirmed. In addition, although the concentration of Sm segregated in a secondary phase 20 due to the segregation of La, a second secondary phase 22 was not present. Therefore, it could not be confirmed that the concentration of the first secondary phase 21 was higher than that of the second secondary phase 22 in terms of Sm concentration, nor could it be confirmed that the concentration of the second secondary phase 22 was higher than that of the first secondary phase 21 in terms of Co concentration. Furthermore, when evaluating the magnetic properties of the sample using the method described above, the remanent magnetic flux density was "poor," the coercivity was "good," the temperature coefficient of the remanent magnetic flux density was "good," the temperature coefficient of the coercivity was "good," and the magnetic properties were "poor." This resulted in the following: in addition to being manufactured using hot working, the coercivity was significantly increased to the level of rare-earth sintered magnet 1 with added Dy due to the addition of Co. Furthermore, La and Sm were present in the main phase 10 or the secondary phase 20, and the magnetic powder was refined, resulting in good temperature coefficients of the remanent magnetic flux density and the coercivity. However, due to the difficulty in aligning the magnetic moments, the remanent magnetic flux density decreased, and the magnetic properties deteriorated. Even when the composition ratio of Nd, La, and Sm was changed, approximately the same results as in Comparative Example 12 were obtained.

[0160] Comparative Example 14 is a sample of a rare earth sintered magnet 1 manufactured according to the manufacturing method described in Patent Document 2, which includes heat treatment, using Nd, Pr, La, Sm, Fe, and FeB in the form of (Nd, Pr, La, Sm)-Fe-BM and Co as element M. When the microstructure of the sample was observed according to the above method, in addition to the addition of Pr, a core-shell structure was confirmed due to heat treatment, but only the main phase 10 with a high concentration of Pr in the core was confirmed to have a core-shell structure. In addition, although the concentration of Sm segregated into a secondary phase 20 due to the segregation of La due to the addition of La and Sm, a second secondary phase 22 was not present. Furthermore, it could not be confirmed that the first secondary phase 21 had a higher concentration of Sm than the second secondary phase 22, nor could it be confirmed that the second secondary phase 22 had a higher concentration of Co than the first secondary phase 21. Furthermore, when evaluating the magnetic properties of the sample using the aforementioned method, the remanent magnetic flux density was "poor," the coercivity was "good," the temperature coefficient of the remanent magnetic flux density was "good," the temperature coefficient of the coercivity was "good," and the magnetic properties were "poor." This results reflect the following: In addition to the hot-working process, due to the formation of a core-shell structure with a high Pr concentration in the core and the addition of Co, the coercivity was significantly increased to the level of rare-earth sintered magnet 1 with added Dy. La and Sm are present in the main phase 10 or the secondary phase 20, resulting in good temperature coefficients for the remanent magnetic flux density and the coercivity. However, due to the difficulty in aligning the magnetic moments, the remanent magnetic flux density decreased, and the magnetic properties deteriorated.

[0161] The samples in Examples 1 to 8 are rare earth sintered magnets 1, which have: a main phase 10, wherein R is one or more rare earth elements selected from Nd and Pr, and M is one or more elements selected from Ga, Al, Cu, and Co, and the main phase 10 satisfies the general formula (Nd, Pr, R)-Fe-BM, containing Nd2Fe 14The structure is based on B crystal grains; and a secondary phase 20, which exists between the main phase 10 and the main phase 10, the main phase 10 having cores 11c, 12c and shells 11s, 12s covering the cores 11c, 12c, wherein, with respect to the main phase 10, a first main phase 11 with CNd > CPr and a second main phase 12 with CNd < CPr are mixed. Furthermore, the secondary phase 20 is characterized by having a first crystalline secondary phase 21, whose main component is an oxide phase represented as (Nd, Pr, La, Sm)-O containing element M as a trace element, and a second crystalline secondary phase 22, whose main component is an oxide phase represented as (Nd, Pr, La)-O containing element M as a trace element, wherein, with respect to the concentration of Sm, the first secondary phase 21 is higher than the second secondary phase 22, and with respect to the concentration of element M, the second secondary phase 22 is higher than the first secondary phase 21. When evaluating the magnetic properties of the samples from Examples 1 to 8 according to the above method, the remanent magnetic flux density was "good", the coercivity was "good", the temperature coefficient of the remanent magnetic flux density was "good", the temperature coefficient of the coercivity was "good", and the magnetization performance was "equivalent or better". As a result, the following effects were achieved: these rare earth sintered magnets 1 did not use expensive and geographically unevenly distributed heavy rare earth elements with procurement risks, and the use of Nd was suppressed, and they exhibited superior magnetic properties and magnetization compared to the past.

[0162] The above embodiments illustrate one example, and can also be combined with other known technologies. The embodiments can also be combined with each other, and without departing from the spirit, some parts of the structure can be omitted or changed.

[0163] Explanation of reference numerals in the attached figures

[0164] 1 Rare earth sintered magnet, 10 Main phase, 11 First main phase, 11c, 12c core, 11s, 12s shell, 12 Second main phase, 20 Sub-phase, 21 First sub-phase, 22 Second sub-phase, 41 High concentration section, 42 Low concentration section, 100 Rotor, 101 Rotor core, 102 Magnet insertion hole, 120 Rotating machine, 130 Stator, 131 Tooth, 132 Winding wire.

Claims

1. A rare-earth sintered magnet, characterized in that, It has a main phase that, when R is one or more rare earth elements selected from Nd and Pr, and M is one or more elements selected from Ga, Al, Cu, and Co, satisfies the general formula (Nd, Pr, R)-Fe-BM, containing Nd2Fe. 14 B is a crystal structure based on grains; and a secondary phase, which forms between the main phase and the main phase. The main phase has a core and a shell covering the core. When the concentration of Nd in the core is set to CNd and the concentration of Pr in the core is set to CPr, the main phase has a first main phase with CNd > CPr and a second main phase with CNd < CPr. The first main phase and the second main phase are mixed. The secondary phase has a first secondary phase and a second secondary phase with crystalline properties, mainly composed of an oxide phase of (Nd, Pr, R)-O containing element M as a trace component. Regarding the concentration of element M, the second phase is higher than the first phase.

2. The rare earth sintered magnet according to claim 1, characterized in that, When analyzing the rare earth sintered magnet using an electron probe microanalyzer, the detection intensity of the electron probe microanalyzer is lower than the average detection intensity of element M for the concentration of element M in the first subphase, and higher than the average detection intensity of element M for the concentration of element M in the second subphase.

3. The rare earth sintered magnet according to claim 1, characterized in that, The number of the first principal phase is greater than the number of the second principal phase.

4. The rare earth sintered magnet according to claim 1, characterized in that, When the Nd concentration in the shell is set to SNd and the Pr concentration in the shell is set to SPr, The first principal phase satisfies the relationships CNd > SNd and CPr < SPr. The second principal phase satisfies the relationship CNd<SNd、CPr>SPr.

5. The rare earth sintered magnet according to claim 1, characterized in that, When R is La or Sm, the secondary phase has: a first crystalline secondary phase with an oxide phase represented as (Nd, Pr, La, Sm)-O containing element M as a trace component as the main component, and a second crystalline secondary phase with an oxide phase represented as (Nd, Pr, La)-O containing element M as a trace component as the main component. In terms of Sm concentration, the first phase is higher than the second phase.

6. A method for manufacturing a rare earth sintered magnet, comprising the method for manufacturing a rare earth sintered magnet according to any one of claims 1 to 5, characterized in that, include: A melting process in which raw materials of a rare earth sintered magnet alloy containing elements constituting the rare earth sintered magnet are melted. The first cooling process involves cooling the molten raw material in the melting process to obtain a solidified alloy. The solidified alloy is further cooled to obtain a second cooling process for the rare earth sintered magnet alloy. The crushing process of the rare earth sintered magnet alloy satisfying (Nd, Pr, R)-Fe-BM. A molding process for preparing a molded body by molding the powder of the rare earth sintered magnet alloy pulverized in the crushing process. A sintering process in which the molded body is sintered at a specified temperature, i.e., a sintering temperature, to obtain a sintered body; The first aging process involves holding the sintered body at a temperature below the sintering temperature, i.e., the first aging temperature. The second aging process involves holding the sintered body, which was held in the first aging process, at a temperature lower than the first aging temperature, i.e., the second aging temperature. A third aging process is performed in which the sintered body held in the second aging process is held again at the first aging temperature. The sintered body held in the third aging process is then held in a fourth aging process at the second aging temperature; A cooling process that cools the sintered body held in the fourth aging process.

7. A rotor, characterized in that, include: The rotor core and the rare earth sintered magnet disposed on the rotor core according to any one of claims 1 to 5.

8. A rotating machine, characterized in that, include: The rotor according to claim 7, and the annular stator having a winding with teeth protruding toward the rotor on the inner surface of one side where the rotor is disposed, and the stator being disposed opposite to the rotor.

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