Rare earth magnet and rare earth magnetic powder

Abstract

The objective of this invention is to provide a rare-earth magnet that can be easily magnetized and maintains high coercivity at high temperatures. The rare-earth magnet of this invention is characterized by comprising a rare-earth magnet having an R²T... 14 The main phase grains of type B crystal structure, where R is a rare earth element and T is a transition metal element, are composed of the following composition based on the molar ratio of the main phase: (R...) 1 （1‑x‑y‑z） Ce x La y Y z 2TM 14 B represents R, where R is the most significant element. 1 For a rare earth element to be selected from the group consisting of Nd, Gd, Tb, Dy, and Ho, TM is an element containing one or more transition metal elements, and 0≤x+y+z≤1 and 0.45≤y+z≤1, in the formula of Cronmiller, i.e. H c =α·H a -N eff ·M s When representing magnetic properties, N eff And the value of α satisfies N eff ≥1.4×α-0.095.

Description

Technical Field

[0001] This invention relates to a method comprising having R2T 14 RTB-based rare-earth magnets and rare-earth magnetic powders with a B-type crystal structure (where R represents rare-earth elements and T represents transition metal elements). Background Technology

[0002] RTB-based rare earth magnets include those with R2T 14 The main phase (grains) of the magnetic phase in a type B crystal structure, due to its ability to achieve high remanence, is commonly used in drive motors for hybrid and electric vehicles. As an RTB-based rare-earth magnet, one known magnet has a main phase composition of (R... 1-x (Y) 1-z La z ) x 2T 14 B (where R represents a specified rare earth element and T represents a specified transition metal element), and the R2T of the tetragonal crystal of the main phase is specified. 14 The presence ratio of Y (yttrium) occupying the 4f and 4g sites in the B-type crystal structure (Patent Document 1). Furthermore, it is known that a magnet has an overall composition in terms of molar ratio determined by formula (R... 1 （1-x） La x ) y (Fe) （1-z） Co z ) （100-y-w-v） B w M 1 v (where R) 1 M is a specified rare earth element. 1 For the specified elements and unavoidable impurity elements. ) represents, and the Kronmuller formula (H) represents the magnetic properties. c =α·H a -N eff ·M s In this context, α is limited to 0.30 to 0.70 (Patent Document 2).

[0003] Patent Document 1: Japanese Patent No. 5708888

[0004] Patent Document 2: Japanese Patent No. 7303157 Summary of the Invention

[0005] In the RTB-based rare-earth magnet described in Patent Document 1, when the molar ratio of Nd in the main phase of rare-earth elements is low, the coercivity H... cIt is possible that the coercivity will decrease. Furthermore, in the RTB-based rare-earth magnets described in Patent Document 2, the coercivity is too high at room temperature, making magnetization difficult, and the coercivity H decreases with increasing temperature. c It may decline.

[0006] The present invention was made in view of this, and its object is to provide a rare earth magnet and a rare earth magnetic powder that can be easily magnetized and maintain a large coercivity at high temperatures.

[0007] To address the aforementioned issues, the present invention provides a rare-earth magnet comprising, as having an R2T 14 The main phase grains of type B crystal structure, wherein R is a rare earth element and T is a transition metal element, and the molar ratio composition of the main phase is given by the formula (R... 1 （1-x-y-z） Ce x La y Y z 2TM 14 B represents, where R 1 For a rare earth element selected from the group consisting of Nd, Gd, Tb, Dy, and Ho, TM is an element containing at least one transition metal element from Fe and Co, and 0 ≤ x + y + z ≤ 1 and 0.45 ≤ y + z ≤ 1, defined by Cronmiller's formula H. c =α·H a -N eff ·M s When representing magnetic properties, N eff And the value of α satisfies N eff ≥1.4×α-0.095, where H c For coercivity [T], α is the factor contributing to the discontinuity between grains, and H a For anisotropic magnetic field [T], N eff The factor M that contributes to the grain size. s For saturation magnetization [T].

[0008] Furthermore, the rare earth magnetic powder of the present invention comprises, as having R2T 14 The main phase grains of type B crystal structure, where R is a rare earth element and T is a transition metal element, the molar ratio composition of the main phase is given by the formula (R... 1 （1-x-y-z） Ce x La y Y z 2TM 14 B represents, where R 1For a rare earth element selected from the group consisting of Nd, Gd, Tb, Dy, and Ho, TM is an element containing at least one transition metal element from Fe and Co, and 0 ≤ x + y + z ≤ 1 and 0.45 ≤ y + z ≤ 1, defined by Cronmiller's formula H. c =α·H a -N eff ·M s When representing magnetic properties, N eff And the value of α satisfies N eff ≥1.4×α-0.095, where H c For coercivity [T], α is the factor contributing to the discontinuity between grains, and H a For anisotropic magnetic field [T], N eff The factor M that contributes to the grain size. s For saturation magnetization [T].

[0009] Invention Effects

[0010] According to the present invention, magnetization can be easily performed and a large coercivity can be maintained at high temperatures. Attached Figure Description

[0011] Figure 1 (a) ~ Figure 1 (c) are schematic cross-sectional views of the rare earth magnets according to embodiments 1 to 3.

[0012] Figure 2 A schematic diagram showing the experimental process for the manufacture and property evaluation of rare earth magnetic powders for samples No.1 to No.31.

[0013] Figure 3 The relationship between ([La]+[Y]) / [TRE] and the slope of coercivity Hc[kOe] at room temperature (300K) to 453K in rare earth magnetic powders of samples No.1 to No.31 (Examples 1 to 21 and Comparative Examples 1 to 10) is shown in a graph on a two-dimensional coordinate system.

[0014] Figure 4 It is the rare earth magnetic powder of samples No.1 to No.31 (Examples 1 to 21 and Comparative Examples 1 to 10) containing Cronmuller's formula (H c =α·H a -N eff ·M s α and N eff The relationship is shown in a graph on a two-dimensional coordinate system.

[0015] Figure 5The ([La]+[Y]) / [TRE], α, and N content in the rare earth magnetic powders of samples No.1 to No.31 (Examples 1 to 21 and Comparative Examples 1 to 10) is determined by the concentration of these components. eff The relationship is shown in a graph on three-dimensional coordinates. Detailed Implementation

[0016] The following describes embodiments of the rare earth magnets and rare earth magnetic powders involved in this invention.

[0017] First, the rare earth magnets and rare earth magnetic powders involved in the first to third embodiments will be illustrated and explained. Figure 1 (a) ~ Figure 1 (c) are schematic cross-sectional views of the rare earth magnets according to embodiments 1 to 3.

[0018] like Figure 1 As shown in (a), the rare-earth magnet 30 according to the first embodiment is a bonded magnet comprising the rare-earth magnetic powder 20 and the adhesive resin 25 according to the first embodiment. The rare-earth magnetic powder 20 comprises as having R2T 14 The rare earth magnetic particles 23 are the main phase grains 23a of the B-type crystal structure. The binder resin 25 comprises a thermosetting resin. The rare earth magnetic particles 23 of the rare earth magnetic powder 20 are bonded together by the binder resin 25. In the rare earth magnet 30, the molar ratio of the rare earth magnetic powder 20 grains 23a (main phase) is determined by the compositional formula (R... 1 （1-x-y-z） Ce x La y Y z 2TM 14 B (where R) 1 For rare earth elements selected from the group consisting of Nd, Gd, Tb, Dy, and Ho, TM is an element containing at least one transition metal element from Fe and Co, and 0 ≤ x + y + z ≤ 1 and 0.45 ≤ y + z ≤ 1. Then, in the formula of Cronmiller, i.e. H... c =α·H a -N eff ·M s When representing the magnetic properties of rare earth magnets 30 and rare earth magnetic powders 20, N eff And the value of α satisfies N eff ≥1.4×α-0.095.

[0019] The rare-earth magnet 30 (bonded magnet) according to the first embodiment is manufactured, for example, using the rare-earth magnetic powder 20 (e.g., powder from a quenched zone) and binder resin 25 according to the first embodiment. The manufacturing method of the rare-earth magnet 30 includes, for example, a step of obtaining a mixture for bonding magnets by mixing the rare-earth magnetic powder 20 and binder resin 25 according to the first embodiment; a step of filling the mixture for bonding magnets into a mold; a step of obtaining a molded body by compressing the mixture for bonding magnets in the mold; and a step of obtaining the bonded magnet by heating the molded body to cure the thermosetting resin of the binder resin 25. In this manufacturing method, in the step of obtaining the molded body, the mixture for bonding magnets can be compressed and molded after applying an orientation magnetic field, or simultaneously with applying an orientation magnetic field to the mixture for bonding magnets.

[0020] The rare earth magnet 30 (bonded magnet) according to the first embodiment includes a component having R2T 14 The composition formula (RB) of the main phase grain 23a of a type B crystal structure of rare-earth magnets, representing the molar ratio of the main phase. 1 （1-x-y-z） Ce x La y Y z 2TM 14 The sum of y and z in B (y+z) (the molar ratio of the sum of La and Y relative to the molar ratio of the sum of rare earth elements in the main phase) is greater than 0.45, and according to Cronmiller's formula (H) c =α·H a -N eff ·M s When N represents the magnetic properties of rare earth magnetic powder 20, N eff And the value of α satisfies N eff ≥1.4×α-0.095. Therefore, in rare-earth magnets 30, the coercivity H at room temperature (e.g., 300K) is... c It is not too large and can be easily magnetized. Furthermore, it can effectively suppress the coercivity H that increases with temperature. c The coercivity decreases. Therefore, it can be easily magnetized and can maintain a large coercivity at high temperatures (e.g., 453K). Furthermore, according to the rare earth magnetic powder 20 of the first embodiment, a rare earth magnet that is easy to magnetize and maintains a large coercivity at high temperatures can be realized.

[0021] like Figure 1 As shown in (b), the rare earth magnet 50 according to the second embodiment includes a magnet having an R2T 14The B-type crystal structure comprises a main phase grain 43 and a grain boundary phase 45 surrounding the grain 43. In the rare-earth magnet 50, the easy magnetization axis of the grain 43 (main phase) is oriented, imparting anisotropy. In the rare-earth magnet 50, the shape of the grain 43, viewed from a direction approximately orthogonal to the easy magnetization axis, is a flat shape with its length direction approximately orthogonal to the easy magnetization axis and its width direction approximately parallel to the easy magnetization axis. In the rare-earth magnet 50, the molar ratio of the grain 43 (main phase) is determined by the formula (R... 1 （1-x-y-z） Ce x La y Y z 2TM 14 B (where R) 1 For rare earth elements selected from the group consisting of Nd, Gd, Tb, Dy, and Ho, TM is an element containing at least one transition metal element from Fe and Co, and 0 ≤ x + y + z ≤ 1 and 0.45 ≤ y + z ≤ 1. Then, in the formula (H) by Cronmiller... c =α·H a -N eff ·M s When representing the magnetic properties of rare-earth magnet 50, N eff And the value of α satisfies N eff ≥1.4×α-0.095.

[0022] The rare-earth magnet 50 (hot-worked magnet) according to the second embodiment is manufactured, for example, using the rare-earth magnetic powder 40 according to the second embodiment (e.g., powder from a quenched zone). The rare-earth magnetic powder 40 contains, as an R2T... 14 Type B crystal structure consists of rare earth magnetic particles in the main phase grains and grain boundary phases. In rare earth magnetic powder 40, the molar ratio of the grains (main phase) is determined by the above composition formula (R...). 1 （1-x-y-z） Ce x La y Y z 2TM 14 B represents. Then, when expressing the magnetic properties of rare-earth magnetic powder 40 using Cronmiller's formula, N... eff And the value of α satisfies N eff ≥1.4×α-0.095. The manufacturing method of rare earth magnet 50 (hot-working magnet) includes, for example, a step of obtaining a sintered body by sintering rare earth magnetic powder 40 under pressure; and a step of obtaining a hot-working magnet by thermoplastic processing of the sintered body.

[0023] According to the rare earth magnet 50 (hot-worked magnet) of the second embodiment, for the same reasons as the rare earth magnet 30 (bonded magnet) of the first embodiment, it can be easily magnetized and can maintain a large coercivity at high temperatures (e.g., 453K). Furthermore, according to the rare earth magnetic powder 40 of the second embodiment, a rare earth magnet that is easily magnetized and maintains a large coercivity at high temperatures can be realized.

[0024] like Figure 1 As shown in (c), the rare earth magnet 70 according to the third embodiment includes a magnet having an R2T 14 A sintered magnet with a B-type crystal structure consisting of a main phase grain 63 and a grain boundary phase 65 surrounding the grain 63. In the rare-earth magnet 70, the molar ratio of grain 63 (main phase) is determined by the composition formula (R... 1 （1-x-y-z） Ce x La y Y z 2TM 14 B (where R) 1 For rare earth elements selected from the group consisting of Nd, Gd, Tb, Dy, and Ho, TM is an element containing at least one transition metal element from Fe and Co, and 0 ≤ x + y + z ≤ 1 and 0.45 ≤ y + z ≤ 1. Then, in the formula (H) by Cronmiller... c =α·H a -N eff ·M s When representing the magnetic properties of rare-earth magnet 70, N eff And the value of α satisfies N eff ≥1.4×α-0.095.

[0025] The rare-earth magnet 70 (sintered magnet) according to the third embodiment is manufactured, for example, using the rare-earth magnetic powder 60 according to the third embodiment. The rare-earth magnetic powder 60 contains, as R2T... 14 Type B crystal structure consists of rare earth magnetic particles in the main phase grains and grain boundary phases. In rare earth magnetic powder 60, the molar ratio of the grains (main phase) is determined by the above composition formula (R...). 1 （1-x-y-z） Ce x La y Y z 2TM 14 B represents. Then, when expressing the magnetic properties of rare-earth magnetic powder 60 using Cronmiller's formula, N... eff And the value of α satisfies N eff≥1.4×α-0.095. The manufacturing method of rare earth magnet 70 (sintered magnet) includes, for example, a step of obtaining a magnetic field shaped body by compressing rare earth magnetic powder 60 in a magnetic field; and a step of obtaining a sintered magnet by pressurizing and sintering the magnetic field shaped body.

[0026] According to the rare-earth magnet 70 (sintered magnet) of the third embodiment, for the same reasons as the rare-earth magnet 30 (bonded magnet) of the first embodiment, it can be easily magnetized and can maintain a large coercivity at high temperatures (e.g., 453K). Furthermore, according to the rare-earth magnetic powder 60 of the third embodiment, a rare-earth magnet that is easily magnetized and maintains a large coercivity at high temperatures can be realized.

[0027] Next, the structure of the rare earth magnets and rare earth magnetic powders involved in the embodiments will be described in further detail.

[0028] 1. Rare earth magnets

[0029] The rare earth magnets involved in the implementation method are those that contain R2T. 14 For rare-earth magnets with a B-type crystal structure (where R represents rare-earth elements and T represents transition metal elements), there are no particular limitations on the grain size of the main phase. The grain size (main phase) of a rare-earth magnet has an R²T structure. 14 The magnetic phase with a B-type crystal structure (sometimes referred to as "R2T" in this specification) 14 Phase B).

[0030] The composition of the main phase molar ratio of rare earth magnets only needs to be determined by the composition formula (R). 1 （1-x-y-z） Ce x La y Y z 2TM 14 B (where R) 1 For rare earth elements selected from the group consisting of Nd, Gd, Tb, Dy, and Ho, TM is an element containing at least one transition metal element from Fe and Co, and the following conditions apply: 0≤x≤0.55, 0≤y≤1, 0≤z≤1, 0≤x+y+z≤1, and 0.45≤y+z≤1. (The symbol ) indicates that there are no special restrictions. Nd is neodymium, Gd is gadolinium, Tb is terbium, Dy is dysprosium, Ho is holmium, Fe is iron, and Co is cobalt.

[0031] The term TM is not particularly limited as long as it contains at least one transition metal element selected from Fe and Co. However, in addition to the aforementioned transition metal element, it may also contain unavoidable impurity elements, or in addition to the aforementioned transition metal element, it may also contain at least one element other than transition metal elements and rare earth elements, as well as unavoidable impurity elements. Here, "unavoidable impurity elements" refers to impurity elements that are unavoidable in the manufacture of the rare earth magnets and rare earth magnetic powders involved in the embodiments, or whose presence would significantly increase manufacturing costs if avoided.

[0032] As for the one or more transition metal elements included in the aforementioned TM, there is no particular limitation as long as they contain at least one of Fe and Co and can obtain the desired magnetic properties of the rare earth magnets and rare earth magnetic powders involved in the embodiments. For example, in addition to at least one of Fe and Co, they may also contain one or more transition metal elements selected from the group consisting of Ni (nickel), Cu (copper), Cr (chromium), Mn (manganese), W (tungsten), V (vanadium), Ti (titanium), and Mo (molybdenum). As for the one or more elements included in the aforementioned TM other than transition metal elements and rare earth elements, there is no particular limitation as long as they contain one or more elements that can obtain the desired magnetic properties of the rare earth magnets and rare earth magnetic powders involved in the embodiments. For example, they may also contain one or more elements selected from the group consisting of Ga (gallium), Al (aluminum), and C (carbon). In addition, Al (aluminum) and C (carbon) may be included as unavoidable impurity elements in the aforementioned TM.

[0033] As rare-earth magnets, in addition to the main phase of grains, they can also contain grain boundary phases surrounding the grains (main phase). Compared to the grains (main phase), the grain boundary phase contains more rare-earth elements R (R0). 1 R-enriched phases of Ce, La and Y.

[0034] Regarding rare earth magnets, according to Cronmiller's formula, H... c =α·H a -N eff ·M s (where H) c For coercivity [T], α is the factor contributing to the discontinuity between grains, and H a For anisotropic magnetic field [T], N eff The factor M that contributes to the grain size. s For saturation magnetization [T]. When representing magnetic properties, as long as N... eff And the value of α satisfies N effIf ≥1.4×α-0.095, then there are no particular limitations. Furthermore, in Cronmiller's formula (H... c =α·H a -N eff ·M s When ) represents the magnetic properties of rare-earth magnets, regarding the coercivity H c [T], using values ​​measured in rare-earth magnets, relating to the anisotropic magnetic field H. a [T] and saturation magnetization M s [T], using only a portion of the magnetic phase in rare-earth magnets, namely the grain (main phase) (with R2T) 14 The value was determined in the magnetic phase of a single crystal with a B-type crystal structure.

[0035] Examples of rare-earth magnets include, for example, the bonded magnet of the first embodiment, the hot-worked magnet of the second embodiment, and the sintered magnet of the third embodiment. In rare-earth magnets, especially hot-worked magnets or bonded magnets, nanocrystalline grains (main phase) are preferred. In this specification, "nanocrystalline grains" refers to grains with an average particle size of less than 1.0 μm. Here, the "average particle size" is measured as follows: In a scanning electron microscope image or a transmission electron microscope image, a certain region is defined as observed from the direction perpendicular to the easy magnetization axis. Multiple lines are drawn perpendicular to the easy magnetization axis for the grains (main phase) present in this region. The diameter (length) of the grain is calculated (cutting method) based on the distance between the points where the lines intersect within the grain particles. If the cross-section of the grain is close to a circle, it is converted to the equivalent diameter of the projected area circle. If the cross-section of the grain is close to a rectangle, it is converted to a cuboid approximation. The diameter (length) distribution (particle size distribution) obtained in this way is then calculated using the D... 50 The value is the average particle size.

[0036] 2. Rare earth magnetic powders

[0037] The rare earth magnetic powder involved in the implementation method is as long as it contains R2T 14 For rare earth magnetic powders with a B-type crystal structure (where R represents rare earth elements and T represents transition metal elements), there are no particular limitations on the grain size of the main phase. The grain size (main phase) of the rare earth magnetic powder is R₂T. 14 Phase B. The molar ratio composition of the main phase of the rare-earth magnetic powder is the same as that of the main phase of the rare-earth magnet described in the embodiment. As a rare-earth magnetic powder, in addition to the grains that form the main phase, it may also contain grain boundary phases existing around the grains (main phase). Compared to the grains (main phase), the grain boundary phase contains a greater amount of rare-earth elements R (R0). 1 R-enriched phases of Ce, La and Y.

[0038] Regarding rare-earth magnetic powders, similarly to the rare-earth magnets involved in the embodiments, in accordance with Cronmuller's formula (H c =α·H a -N eff ·M s When representing magnetic properties, as long as N eff And the value of α satisfies N eff If ≥1.4×α-0.095, then there are no particular limitations. Furthermore, in Cronmiller's formula (H... c =α·H a -N eff ·M s When ) represents the magnetic properties of rare earth magnetic powders, regarding the coercivity H c [T], a value determined using rare-earth magnetic powder as a whole, relating to the anisotropic magnetic field H. a [T] and saturation magnetization M s [T], using only a portion of the magnetic phase in rare earth magnetic powders, i.e., the grain (main phase) (with R2T) 14 The value was determined in the magnetic phase of a single crystal with a B-type crystal structure.

[0039] As a rare-earth magnetic powder, it can be a powder with quenched bands (magnetic thin strips) obtained by rapidly quenching molten metal of an alloy with a composition corresponding to the overall composition of the rare-earth magnetic powder using a liquid quenching method (liquid quenched powder), which is then pulverized as needed. Alternatively, the powder with quenched bands can be subjected to a crystallization heat treatment to crystallize the structure of the quenched bands (crystallized liquid quenched powder). This powder with quenched bands is used, for example, in the manufacture of heat-processed magnets or bonded magnets. Furthermore, as a rare-earth magnetic powder, it can also be a powder of magnetic particles manufactured by pulverizing an alloy with a composition corresponding to the overall composition of the rare-earth magnetic powder using a grinding mill or the like. This powder of magnetic particles is used, for example, in the manufacture of sintered magnets or bonded magnets. In the case of rare-earth magnetic powders, especially quenched band powders, nanocrystalline grains (main phase) are preferred.

[0040] Example

[0041] The following examples and comparative examples provide a more detailed description of the rare earth magnets and rare earth magnetic powders involved in the embodiments.

[0042] <<Experiments in the manufacture and evaluation of rare earth magnetic powders>>

[0043] Rare earth magnetic powders, which were used as examples and comparative examples (samples No. 1 to No. 31), were prepared, and experiments were conducted to evaluate their magnetic properties. Figure 2This is a schematic diagram showing the experimental process for manufacturing and evaluating the properties of rare earth magnetic powders for samples No.1 to No.31.

[0044] Manufacturing of rare earth magnetic powders

[0045] Rare earth magnetic powders, used as samples No. 1 to No. 31, were used to manufacture a product containing R2T. 14 Type B (where R represents rare earth elements and T represents transition metal elements) crystal structure, the main phase grains, and the molar ratio composition of the main phase is determined by the formula (R... 1 （1-x-y-z） Ce x La y Y z 2TM 14 B (where R) 1 Rare earth magnetic powder is defined as an element selected from the group consisting of Nd, Gd, Tb, Dy, and Ho, where TM is an element containing at least one transition metal element selected from Fe and Co, and 0 ≤ x + y + z ≤ 1.

[0046] First, such as Figure 2 As shown in the <Alloy Manufacturing>, alloys of materials for the rare earth magnetic powders of Samples No. 1 to No. 31 were prepared by alloying a variety of specified raw materials using electric arc melting. First, for the preparation of each alloy of Samples No. 1 to No. 31, a variety of specified raw materials were weighed. Specifically, to achieve the overall molar ratio [at%] of each rare earth magnetic powder of Samples No. 1 to No. 31 as shown in Table 1 below, a variety of specified raw materials were weighed so that the total atomic percentage (at%) of rare earth elements (Nd, Ce, La, and Y), elements containing transition metal elements (Fe, Co, Ga, and Cu), and boron (B) of the specified raw materials used in each alloy of Samples No. 1 to No. 31 reached specified values. Next, the specified raw materials weighed for each alloy of Samples No. 1 to No. 31 were dissolved using an electric arc melting apparatus (an automatic electric arc melting furnace manufactured by DIAVAC LIMITED). As a result, samples No. 1 to No. 31 were prepared.

[0047] Next, as Figure 2As shown in the paper "Preparation, Composition, and Coercivity Evaluation of Rare Earth Magnetic Powders," liquid quenched powders were prepared from each alloy of Samples No. 1 to No. 31. First, molten metals of each alloy of Samples No. 1 to No. 31 were prepared. Then, using a liquid quenching method, the molten metals of each alloy were rapidly quenched in a liquid quenching apparatus by spraying them from a nozzle onto the surface of a rotating cooling roller, thereby producing powders of quenched bands (magnetic strips). Thus, liquid quenched powders (powders of quenched bands) for Samples No. 1 to No. 31 were prepared.

[0048] Next, as Figure 2 As shown in the report "Manufacturing, Composition, and Coercivity Evaluation of Rare Earth Magnetic Powders," the liquid quenched powders of samples No. 1 to No. 31 underwent crystallization heat treatment. During this process, each liquid quenched powder was subjected to a short-term heat treatment at 680°C for 5 minutes in a heat treatment furnace. This resulted in the crystallization of the quenched zone structure in each liquid quenched powder. Thus, the rare earth magnetic powders of samples No. 1 to No. 31 (crystallized liquid quenched powders) were manufactured.

[0049] Composition and coercivity of rare earth magnetic powders H c [Evaluation]

[0050] Next, as Figure 2 As shown in the report "Preparation, Composition, and Coercivity Evaluation of Rare Earth Magnetic Powders", the overall composition and coercivity H of each rare earth magnetic powder from samples No. 1 to No. 31 were evaluated at various temperatures including room temperature (300K), 348K, 373K, and 453K. c [T]. In the evaluation of the overall composition of rare earth magnetic powders, the molar composition [at%] of each rare earth magnetic powder was determined by ICP (inductively coupled plasma) luminescence spectroscopy. The results are shown in Table 1 below. Coercivity H at various temperatures of room temperature (300K), 348K, 373K, and 453K. c In the evaluation of [T], after the rare earth magnetic powders were fixed in resin filled with thermosetting resin (GM-6600 manufactured by Breny Techno Research Co., Ltd.), the coercivity H at various temperatures of room temperature (300K), 348K, 373K, and 453K was measured using a VSM (sample vibration magnetization measuring device, Lake Shore 8600 Series) and a physical property measuring system (PPMS (registered trademark) manufactured by Quantum Design). c[T]. Therefore, the coercivity H at room temperature (300K), 348K, 373K, and 453K was obtained for each rare-earth magnetic powder from samples No.1 to No.31. c The dataset is [T]. The results are shown in Table 1 below.

[0051] [Saturation magnetization M] s and anisotropic magnetic field H a [Evaluation]

[0052] After the preparation of each alloy from Specimen No. 1 to Specimen No. 31, as follows: Figure 2 As shown in the evaluation of saturation magnetization and anisotropic magnetic field, the alloys of samples No. 1 to No. 31 were subjected to homogenization heat treatment. During this process, each alloy was subjected to homogenization heat treatment at 1000°C for 24 hours in a heat treatment furnace. This promoted the grain growth of the main phase (grains) of each alloy.

[0053] Next, as Figure 2 As shown in the evaluation of saturation magnetization and anisotropic magnetic field, the homogenized heat-treated alloys of samples No. 1 to No. 31 were pulverized and classified. After pulverizing the homogenized heat-treated alloys using a shredder (IKA A10basic), the pulverized powder was classified using a sieve, thereby obtaining powder with a particle size of 20 μm or less. This yielded powder (powder with a particle size of 20 μm or less) of near-single-crystal magnetic particles mainly composed of the main phase in the homogenized heat-treated alloys. Furthermore, in the pulverization and classification of these homogenized heat-treated alloys, the main phase is brittle, while the grain boundary phase is relatively viscous; therefore, powder of near-single-crystal magnetic particles mainly composed of the main phase in the alloy can be preferentially obtained.

[0054] Next, as Figure 2 As shown in the evaluation of saturation magnetization and anisotropic magnetic field, the saturation magnetization M of various single-crystal magnetic particle powders from samples No.1 to No.31 was evaluated at temperatures of room temperature (300K), 348K, 373K, and 453K. s [T] and anisotropic magnetic field H a [T]. At this point, firstly, the powder of each type of single-crystal magnetic particle is filled with thermosetting resin and then filled into a Cu container. Under the condition of applying a magnetic field to the powder of magnetic particles, the thermosetting resin is heated to cure it, thereby producing evaluation samples (each bonded magnet of Examples 1 to 21 and Comparative Examples 1 to 10) for oriented the easy magnetization axis direction of the powder of each type of single-crystal magnetic particle.

[0055] Next, for the evaluation samples of various single-crystal magnetic particle powders (Examples 1-21 and Comparative Examples 1-10 bonded magnets) of Samples No. 1 to No. 31, magnetization curves (MH curves) representing the relationship between magnetization M and magnetic field H were obtained by applying a magnetic field of 7T from the easy magnetization axis direction of the magnetic particle powder at various temperatures of room temperature (300K), 348K, 373K, and 453K. Then, the saturation magnetic flux density was calculated from the MH curves obtained at each temperature using the saturation asymptotic method. The calculated saturation magnetic flux density was then divided by the principal phase index of the magnetic particle powder to calculate the saturation magnetization M at each temperature. s [T]. Furthermore, the principal phase fraction (volume fraction of the principal phase) of the powders of various single-crystal magnetic particles from samples No. 1 to No. 31 was determined using ICP emission spectroscopy to analyze the overall composition of the magnetic particle powders, assuming the magnetic particle powder is R2T. 14 Phase separation is achieved by separating the B phase grains (main phase) and grain boundary phases, and the calculation is based on the measured overall composition. Specifically, after obtaining the mass concentration (mass%) of each element in the overall magnetic particle powder based on the measurement results of the overall composition of the magnetic particle powder using ICP emission spectroscopy analysis, the mass ratio of the main phase and the mass ratio of the grain boundary phase in the magnetic particle powder are first calculated. Based on the calculation results of these mass ratios, the volume fraction of the main phase (main phase ratio) and the volume fraction of the grain boundary phase are calculated using the density of each phase.

[0056] Furthermore, for the evaluation samples of various single-crystal magnetic particle powders from Samples No. 1 to Sample No. 31, the anisotropic magnetic field H was determined using the Singular Point Detection (SPD) method at various temperatures of room temperature (300K), 348K, 373K, and 453K. a [T].

[0057] Therefore, for the powders of various single-crystal magnetic particles from samples No.1 to No.31, saturation magnetization M at room temperature (300K), 348K, 373K, and 453K was obtained. s The dataset of [T] and the anisotropic magnetic field H a The dataset is [T]. The results are shown in Table 1 below.

[0058] [α and N in Cronmill's formula representing the magnetic properties of rare earth magnetic powders] eff [Calculation of the value]

[0059] The coercivity H at room temperature (300K), 348K, 373K, and 453K was obtained using rare earth magnetic powders and single-crystal-like magnetic particles from samples No. 1 to No. 31. c The dataset of [T] and the saturation magnetization M s The dataset of [T] and the anisotropic magnetic field H a The dataset [T] was used to calculate the Cronmiller formula (H) representing the magnetic properties of rare earth magnetic powders for samples No.1 to No.31. c =α·H a -N eff ·M s α and N in ) eff The value of .

[0060] Specifically, for the rare earth magnetic powders of samples No.1 to No.31, the coercivity H at various temperatures of room temperature (300K), 348K, 373K, and 453K was measured. c and saturation magnetization M s and anisotropic magnetic field H a The formula input into Cronmiller (H) c =α·H a -N eff ·M s In the process, the value on the left is set as the coercivity H. c The measured value is used as the value on the right, which is set according to the saturation magnetization M. s and anisotropic magnetic field H a The coercivity H was calculated c The predicted values ​​are given by four equations. Then, the sum of the squared errors of the left and right sides of these four equations is calculated to minimize α and N. eff The value of . Therefore, Cronmiller's formula (H) is used to represent the magnetic properties of the rare-earth magnetic powders of samples No.1 to No.31. c =α·H a -N eff ·M s α and N in ) eff The values ​​of α and N were obtained to minimize the sum of the squares of these errors. eff The values ​​are shown in Table 1 below.

[0061] [Investigation of the properties of rare earth magnetic powders based on experimental results]

[0062] Based on the above experimental results, regarding the rare earth magnetic powders of samples No.1 to No.31, the molar ratio of the main phase and the Cronmiller formula (H) are determined. c =α·H a -N eff ·Ms α and N eff The effect of the value on the slope of the coercivity Hc[kOe] at room temperature (300K) to 453K was investigated.

[0063] First, for the rare earth magnetic powders of samples No. 1 to No. 31, the slope of the coercivity Hc[kOe] of the rare earth magnetic powders at room temperature (300K) to 453K was calculated. Then, the coercivity Hc[kOe] of the rare earth magnetic powders at 453K was... c [T] minus the coercivity H at room temperature (300K) c The difference [T] was converted to kilo-Oe (kOe) and then divided by these temperature differences (153K) for calculation. The calculation results are shown in Table 1 below. Then, the rare earth magnetic powders of Sample No. 1 to Sample No. 21, which had a slope of -0.0106kOe / K or higher for the coercivity Hc at room temperature (300K) to 453K and could sufficiently suppress the decrease of coercivity Hc with increasing temperature, were designated as the rare earth magnetic powders of Examples 1 to 21. The rare earth magnetic powders of Sample No. 22 to Sample No. 31, which were not included, were designated as the rare earth magnetic powders of Comparative Examples 1 to 10.

[0064] Furthermore, for each rare-earth magnetic powder from samples No. 1 to No. 31, the composition formula (R) corresponding to the molar ratio of the main phase of the rare-earth magnetic powder was calculated. 1 （1-x-y-z） Ce x La y Y z 2TM 14 B (where R) 1 For rare earth elements selected from the group consisting of Nd, Gd, Tb, Dy, and Ho, TM is an element containing at least one transition metal element from Fe and Co, and 0 ≤ x + y + z ≤ 1. The sum of y and z in (y + z) is ([La] + [Y]) / [TRE].

[0065] (Where, [La] and [Y] are the molar ratios of La and Y in the total rare-earth magnetic powder [at%], respectively, and [TRE] is the total molar ratio of rare-earth elements (Nd, Ce, La, and Y) in the total rare-earth magnetic powder [at%].) The composition [at%] is calculated based on the molar ratios of the total rare-earth magnetic powder as shown in Table 1 below. The calculation results are shown in Table 1 below. Furthermore, in the rare-earth magnetic powders of samples No. 1 to No. 31, the concentration ratio of rare-earth elements (Nd, Ce, La, and Y) in the grain boundary phase is considered as R2T. 14The B phase (main phase) has high grain size, but X-ray diffraction patterns confirmed the absence of specific elemental segregation. Therefore, it is believed that the combined molar ratio of La and Y relative to the combined molar ratio of rare earth elements is substantially the same in both the main phase and the grain boundary phase. Thus, ([La] + [Y]) / [TRE]

[0066] The molar ratio of the total La and Y in the total rare earth magnetic powder relative to the total molar ratio of rare earth elements can be treated in the same way as the sum of y and z (y+z) in the composition formula representing the molar ratio of the main phase of the rare earth magnetic powder (the molar ratio of the total La and Y in the main phase of the rare earth magnetic powder relative to the total molar ratio of rare earth elements).

[0067] Figure 3 The relationship between ([La]+[Y]) / [TRE] and the slope of coercivity Hc[kOe] at room temperature (300K) to 453K in rare earth magnetic powders of samples No.1 to No.31 (Examples 1 to 21 and Comparative Examples 1 to 10) is shown in a graph on a two-dimensional coordinate system. Figure 4 It is the rare earth magnetic powder of samples No.1 to No.31 (Examples 1 to 21 and Comparative Examples 1 to 10) containing Cronmuller's formula (H c =α·H a -N eff ·M s α and N eff The relationship is shown in a graph on a two-dimensional coordinate system. Figure 5 The ([La]+[Y]) / [TRE], α, and N content in the rare earth magnetic powders of samples No.1 to No.31 (Examples 1 to 21 and Comparative Examples 1 to 10) is determined by the concentration of these components. eff The relationship is shown in a graph on three-dimensional coordinates.

[0068] As shown in Table 1 below and Figure 3 As shown, in the rare earth magnetic powders of samples No. 1 to No. 31 (Examples 1 to 21 and Comparative Examples 1 to 10), the slope of the coercivity Hc[kOe] at room temperature (300K) to 453K is related to ([La]+[Y]) / [TRE].

[0069] It is evident that the greater the increase in (y+z) of the composition formula representing the molar ratio of the main phase of the rare earth magnetic powder, the more significant the improvement. Furthermore, it is evident that, especially when ([La]+[Y]) / [TRE] is 0.45 or higher, a favorable value of -0.0106 kOe / K or higher can be obtained as the slope of the coercivity Hc[kOe] at room temperature (300 K) to 453 K, which sufficiently suppresses the decrease in coercivity Hc with increasing temperature. On the other hand, in the rare earth magnetic powders of Comparative Examples 2 and 4, although ([La]+[Y]) / [TRE] is 0.45 or higher, the slope of the coercivity Hc[kOe] at room temperature (300 K) to 453 K is not a favorable value. This is because the coercivity Hc of rare earth magnetic powder cannot be explained solely by the composition of the main phase of the rare earth magnetic powder; it is necessary to consider Cronmiller's formula (H... c =α·H a -N eff ·M s α and N in ) eff Therefore, in the rare earth magnetic powders of samples No. 1 to No. 31 (Examples 1 to 21 and Comparative Examples 1 to 10), in addition to ([La]+[Y]) / [TRE], the values ​​of α and N in Cronmiller's formula were also considered. eff The values ​​are shown in Table 1 below. Figures 3-5 As shown, in the rare earth magnetic powders of Examples 1-21, ([La]+[Y]) / [TRE] is 0.45 or higher, and N eff And the value of α satisfies N eff ≥1.4×α-0.095, thus the slope of the coercivity Hc[kOe] at room temperature (300K) to 453K becomes a good value of -0.0106kOe / K that can effectively suppress the decrease of coercivity Hc with increasing temperature.

[0070] The rare-earth magnetic powders of Examples 1-21 can be used to bond magnets by bonding with an adhesive resin, and can be used to sinter magnets (hot-worked magnets and sintered magnets) by sintering. These magnets can be easily magnetized and can maintain a large coercivity at high temperatures (e.g., 453K).

[0071] [Table 1]

[0072]

[0073] The embodiments of the rare earth magnets and rare earth magnetic powders involved in this invention have been described in detail above. However, this invention is not limited to the embodiments described above. Various design changes can be made without departing from the spirit of this invention as set forth in the claims.

[0074] Symbol Explanation

[0075] 30 - Rare earth magnets, 20 - Rare earth magnetic powders, 23 - Rare earth magnetic particles, 23a - Grains (main phase), 25 - Adhesive resin.

Claims

1. A rare-earth magnet, characterized in that, Included as having R2T 14 The B-type crystal structure consists of the main phase grains, where R represents rare earth elements and T represents transition metal elements. The composition of the main phase molar ratio meter is determined by the composition formula (R). 1 （1-x-y-z） Ce x La y Y z 2TM 14 B represents R, where R is the most significant element. 1 The element is selected from one or more rare earth elements in the group consisting of Nd, Gd, Tb, Dy, and Ho. TM is an element containing at least one transition metal element selected from Fe and Co, and 0 ≤ x + y + z ≤ 1 and 0.45 ≤ y + z ≤ 1. In the formula H by Cronmiller c =α·H a -N eff ·M s When representing magnetic properties, N eff And the value of α satisfies N eff ≥1.4×α-0.095, where H c For coercivity [T], α is the factor contributing to the discontinuity between grains, and H a For anisotropic magnetic field [T], N eff The factor M that contributes to the grain size. s For saturation magnetization [T].

2. A rare earth magnetic powder, characterized in that, Included as having R2T 14 The B-type crystal structure consists of the main phase grains, where R represents rare earth elements and T represents transition metal elements. The composition of the main phase molar ratio meter is determined by the composition formula (R). 1 （1-x-y-z） Ce x La y Y z 2TM 14 B represents R, where R is the most significant element. 1 The element is selected from one or more rare earth elements in the group consisting of Nd, Gd, Tb, Dy, and Ho. TM is an element containing at least one transition metal element selected from Fe and Co, and 0 ≤ x + y + z ≤ 1 and 0.45 ≤ y + z ≤ 1. In the formula H by Cronmiller c =α·H a -N eff ·M s When representing magnetic properties, N eff And the value of α satisfies N eff ≥1.4×α-0.095, where H c For coercivity [T], α is the factor contributing to the discontinuity between grains, and H a For anisotropic magnetic field [T], N eff The factor M that contributes to the grain size. s For saturation magnetization [T].

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