WO2004029999A1 - R-t-b based rare earth element permanent magnet - Google Patents

R-t-b based rare earth element permanent magnet Download PDF

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Publication number
WO2004029999A1
WO2004029999A1 PCT/JP2003/012491 JP0312491W WO2004029999A1 WO 2004029999 A1 WO2004029999 A1 WO 2004029999A1 JP 0312491 W JP0312491 W JP 0312491W WO 2004029999 A1 WO2004029999 A1 WO 2004029999A1
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Prior art keywords
phase
rare earth
permanent magnet
alloy
product
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PCT/JP2003/012491
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French (fr)
Japanese (ja)
Inventor
Chikara Ishizaka
Gouichi Nishizawa
Tetsuya Hidaka
Akira Fukuno
Nobuya Uchida
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Tdk Corporation
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Priority to EP03748612A priority Critical patent/EP1460650B1/en
Priority to JP2004539583A priority patent/JP4076178B2/en
Priority to DE60317460T priority patent/DE60317460T2/en
Publication of WO2004029999A1 publication Critical patent/WO2004029999A1/en

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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/005—Ferrous alloys, e.g. steel alloys containing rare earths, i.e. Sc, Y, Lanthanides
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/02—Making ferrous alloys by powder metallurgy
    • C22C33/0207—Using a mixture of prealloyed powders or a master alloy
    • C22C33/0228—Using a mixture of prealloyed powders or a master alloy comprising other non-metallic compounds or more than 5% of graphite
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/02—Making ferrous alloys by powder metallurgy
    • C22C33/0257—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements
    • C22C33/0278—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements with at least one alloying element having a minimum content above 5%
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
    • H01F1/047—Alloys characterised by their composition
    • H01F1/053—Alloys characterised by their composition containing rare earth metals
    • H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
    • H01F1/0555—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 pressed, sintered or bonded together
    • H01F1/0557—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 pressed, sintered or bonded together sintered
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
    • H01F1/047—Alloys characterised by their composition
    • H01F1/053—Alloys characterised by their composition containing rare earth metals
    • H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
    • H01F1/057—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B
    • H01F1/0571—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes
    • H01F1/0575—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together
    • H01F1/0577—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together sintered
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
    • H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
    • H01F41/0253—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
    • B22F2998/10—Processes characterised by the sequence of their steps
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C2202/00—Physical properties
    • C22C2202/02—Magnetic

Definitions

  • R is one or more rare earth elements, but the rare earth element is a concept including Y
  • T is Fe or at least one element in which Fe and Co are essential
  • the present invention relates to R-T-B rare earth permanent magnets containing the above transition metal elements) and B (boron) as main components. Background technology
  • R-T-B Rare Earth Permanent Magnets are increasing in demand year by year due to their excellent magnetic properties, and the abundant resource of Nd, which is a major component, and their relatively low cost. ing.
  • R-T_B rare earth permanent magnets are also being actively researched and developed to improve their magnetic properties.
  • Japanese Patent Application Laid-Open No. H1_219143 discloses that adding 0.02 to 0.5 at% of Cu to an R-T-B rare-earth permanent magnet improves magnetic properties and heat treatment conditions. Have been reported.
  • the method described in Japanese Patent Application Laid-Open No. 11-219143 requires high magnetic properties required for high-performance magnets, specifically, high coercive force (He J) and residual magnetic flux density (Br). Was inadequate.
  • the magnetic properties of the RTB-based rare earth permanent magnets obtained by sintering sometimes depend on the sintering temperature.
  • the temperature range in which the desired magnetic properties can be obtained is defined as the sintering temperature range.
  • Japanese Patent Application Laid-Open No. 2002-57177 discloses that a fine ZrB compound is contained in an R—T—B-based rare earth permanent magnet containing Co, Al, Cu, and further Zr, Nb, or Hf. It has been reported that by uniformly dispersing and precipitating NbB compounds or HfB compounds (hereinafter referred to as MB compounds), the grain growth during the sintering process is suppressed, and the magnetic properties and the sintering temperature range are improved. Has been done.
  • the sintering temperature range is expanded by dispersing and precipitating the MB compound.
  • the sintering temperature range is as narrow as about 20 ° C. Therefore, in order to obtain high magnetic properties in mass production furnaces, it is desirable to further increase the sintering temperature range. In order to obtain a sufficiently wide sintering temperature range, it is effective to increase the amount of added Zr. However, as the amount of added Zr increases, the residual magnetic flux density decreases, and the originally desired high characteristics cannot be obtained.
  • an object of the present invention is to provide an RTB-based rare earth permanent magnet capable of suppressing grain growth while minimizing deterioration of magnetic properties and further improving the sintering temperature range. Disclosure of the invention
  • the present inventor has found that, when a product rich in Zr is present in the R 2 Ti 4 B phase constituting the main phase of the R—TB rare earth permanent magnet, it is possible to minimize the deterioration of the magnetic properties. It has been found that grain growth can be suppressed and the sintering temperature range can be improved. That is, the present invention relates to an R 2 T 14 B phase (where R is one or more rare earth elements (however, Is a concept that includes Y), ⁇ is a main phase composed of one or more transition metal elements that require Fe or Fe and Co, and a grain boundary that contains more R than the main phase.
  • the present invention provides an RTB-based rare earth permanent magnet comprising a sintered body containing a phase and a Zr-rich product in an R 2 Ti 4 B phase.
  • the product rich in Zr has a plate-like or needle-like form.
  • the amount of oxygen contained in the sintered body is not more than 2000 ppm.
  • the effect of suppressing grain growth and expanding the sintering temperature range due to the presence of Zr-rich products in the R 2 T 14 B phase is due to the fact that the amount of oxygen contained in the sintered body is 200 ppm This is because it becomes remarkable when the oxygen content is as follows.
  • R 28 to 33 wt%
  • B 0.5 to 1.5 wt%
  • Al 0.03 to 0.3 wt%
  • Cu 0.3 wt% or less (excluding 0)
  • Zr 0.05 to 0.2 wt%
  • Co 4 wt% or less (excluding 0)
  • balance substantially Fe It is desirable to have a composition consisting of
  • Fig. 1 is a table showing the combination of the low R alloy and the high R alloy used in the first embodiment and the composition of the obtained permanent magnet.
  • Fig. 2 is the magnetic characteristic of the permanent magnet obtained in the first embodiment.
  • FIG. 3 is a graph showing the relationship between the amount of additive element M (Zr or Ti) of the permanent magnet obtained in the first embodiment and the residual magnetic flux density (Br). Is a graph showing the relationship between the amount of additive element M (Zr or Ti) of the permanent magnet obtained in the first embodiment and the coercive force (H e J), and
  • FIG. 6 is a graph showing the relationship between the added element M (2 1 "or 1) and the squareness ratio (HkZH c J) of the permanent magnet, and FIG.
  • FIG. 7 (a) shows the sample of Example 1 (Zr amount 0.1
  • TEM transmission electron microscope
  • Fig. 9 is a TEM photo of the sample of Example 1 (sample with 0.10 wt% of Zr)
  • Fig. 10 is a TEM photograph of the sample of Example 1 (a sample having a Zr content of 0.10 wt%)
  • Fig. 11 (a) is a sample of the sample of Example 1 (a sample having a Zr content of 0.10 wt%).
  • EPMA Electro Probe Micro Analyzer
  • FIG. 11 Photograph showing the Zr mapping result (lower row) of the sample of Comparative Example 2 (sample having a Zr content of 0.10 wt%) by EPMA (lower row), and a photo showing the composition image of the same field of view as the Zr mapping result (lower row)
  • Fig. 12 is a table showing the magnetic properties of the permanent magnet obtained in the second embodiment
  • Fig. 13 is a graph showing the relationship between the sintering temperature and the residual magnetic flux density (B r) in the second embodiment.
  • FIG. 14 is a graph showing the relationship between the sintering temperature and the coercive force (Hc J) in the second embodiment.
  • FIG. 15 is a graph showing the relationship between the sintering temperature and the squareness ratio (HkZHc J) in the second embodiment.
  • Fig. 16 is a graph showing the relationship
  • Fig. 16 is a graph showing the relationship between the residual magnetic flux density (Br) and the squareness ratio (Hk / Hc J) at each sintering temperature in the second embodiment
  • Fig. 17 is the third embodiment.
  • Fig. 18 is a table showing the combination of low R alloy and high R alloy used in the above and the composition of the obtained permanent magnet.
  • Fig. 18 shows the magnetic properties of the permanent magnet obtained in the third embodiment.
  • FIG. 19 is a chart showing the combination of the low R alloy and the high R alloy used in the fourth embodiment and the composition of the obtained permanent magnet
  • FIG. 20 is a permanent magnet obtained in the fourth embodiment.
  • 5 is a table showing the magnetic characteristics of FIG. BEST MODE FOR CARRYING OUT THE INVENTION
  • the rare earth permanent magnet obtained by the present invention has an R 2 T i 4 B phase (R is one or more rare earth elements (where the rare earth element is a concept including Y), T includes at least a main phase composed of Fe or one or more of transition metal elements in which Fe and Co are essential) and a grain boundary phase containing more R than the main phase.
  • R is one or more rare earth elements (where the rare earth element is a concept including Y)
  • T includes at least a main phase composed of Fe or one or more of transition metal elements in which Fe and Co are essential
  • a grain boundary phase containing more R than the main phase The present invention is characterized in that a Zr-rich product is present in the R 2 T 14 B phase.
  • the R-T-B rare-earth permanent magnet in which this product exists can suppress grain growth while minimizing deterioration of magnetic properties, and can obtain a wide sintering temperature range.
  • This product must be present in the R 2 T 14 B phase, but need not be present in all R 2 T 14 B phases
  • R_T—B-based rare earth permanent magnets Ti has been known as an additional element that forms a product in the R 2 T 14 B phase (for example, Appl. Phys. 69 (1991) 6055). .
  • the present inventor has found that forming a product in the R 2 T i 4 B phase by adding Zr and T i is effective for increasing the sintering temperature range.
  • the magnetic properties specifically the residual magnetic flux density (Br) are reduced even if the amount of addition is sufficient to exert the effect of increasing the sintering temperature range. I can hardly get up.
  • the present inventor has confirmed that there are some manufacturing requirements for the Zr-rich product to be present in the R 2 T 14 B phase. As will be described later series of steps of a method of manufacturing a permanent magnet according to the present invention, it will be described here requirements for products rich in Z r is present in the scale 2 1 ⁇ 4 B Aiuchi.
  • R_T-B rare earth permanent magnets can be produced by using a single alloy that matches the desired composition as the starting material (hereinafter referred to as the single method), or by using multiple alloys having different compositions as the starting material. (Hereinafter referred to as the “mixing method”) You.
  • the mixing method typically uses an alloy mainly composed of the R 2 T 14 B phase (low R alloy) and an alloy containing more R than the low R alloy (high R alloy) as starting materials.
  • the present inventor obtained an RT—B-based rare earth permanent magnet by adding Zr to either the low R alloy or the high R alloy. As a result, it was confirmed that when a permanent magnet was prepared by adding Zr to a low-R alloy, a Zr-rich product was present in the R 2 T 14 B phase. On the other hand, if it is contained Z r on the high R alloys was confirmed that the product-rich Z r is not present in RsT ⁇ 4 B Aiuchi.
  • the chemical composition here refers to the chemical composition after sintering.
  • the rare earth permanent magnet of the present invention contains 25 to 35 wt% of R.
  • R is one or two selected from the group consisting of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu, and Y. More than species. If the amount of R is less than 25 wt%, the generation of the R 2 T 14 B phase which is the main phase of the rare earth permanent magnet is not sufficient. As a result, ⁇ -Fe with soft magnetism precipitates and the coercive force is significantly reduced. On the other hand, when the amount of R exceeds 35 wt%, the volume ratio of the main phase, R 2 T 14 B phase, decreases, and the residual magnetic flux density decreases.
  • the amount of R should be 25-35 wt%.
  • a desirable amount of R is 28 to 33 wt%, and a more desirable amount of R is 29 to 32 wt%.
  • the main component of R be Nd.
  • Dy is effective in increasing the anisotropic magnetic field of the R 2 T 14 B phase and improving the coercive force. Therefore, it is desirable to select Nd and Dy as R, and to make the sum of Nd and Dy 25 to 33 wt%. In this range, the amount of 0 is desirably 0.1 to 8 wt ° / 0 .
  • the amount of Dy is desirably determined within the above range depending on which of the residual magnetic flux density and the coercive force is important. In other words, it is desirable to set the Dy amount to 0.1 to 3.5 wt% to obtain a high residual magnetic flux density, and to set the Dy amount to 3.5 to 8 wt% to obtain a high coercive force.
  • the rare earth permanent magnet of the present invention contains boron (B) in an amount of 0.5 to 4.5 wt%. If B is less than 0.5 wt%, a high coercive force cannot be obtained. However, when B exceeds 4.5 wt%, the residual magnetic flux density tends to decrease. Therefore, the upper limit is set to 4.5wt%.
  • the desirable amount of B is 0.5 to 1.5 wt%, and the more desirable amount of B is 0.8 to: 1.2 wt%.
  • the RTB-based rare earth permanent magnet of the present invention may contain one or two of A1 and Cu in a range of 0.02 to 0.6 wt%.
  • A1 and Cu By including one or two kinds, it is possible to increase the coercive force, the corrosion resistance, and the temperature characteristics of the obtained permanent magnet.
  • a desirable amount of A1 is 0.03 to 0.3 wt%, and a more desirable amount of A1 is 0.05 to 0.25 wt%.
  • the amount of No. 11 is 0.3 wt% or less (excluding 0), preferably 0.15 wt% or less (not including 0), and more preferably 0.03 wt% or less. ⁇ 0.08 wt%.
  • R- T one B system rare earth permanent magnet of the present invention in order to produce a product enriched in Z r in R 2 T i 4 B Aiuchi, to contain Z r 0.03 ⁇ 0. 25 wt% Nozomu Masire,
  • Zr exerts the effect of suppressing the abnormal growth of crystal grains during the sintering process, and changes the structure of the sintered body. Make it uniform and fine. Therefore, the effect of Zr becomes remarkable when the oxygen content is low.
  • the desirable amount of Zr is 0.05 to 0.2 wt%, and the more desirable amount is 0.1 to 0.15 wt%.
  • the R—T—B-based rare earth permanent magnet of the present invention has an oxygen content of 2000 pm or less. If the amount of oxygen is large, the acid phase, which is a nonmagnetic component, increases, and the magnetic properties deteriorate. Therefore, in the present invention, the amount of oxygen contained in the sintered body is set to 2000 ppm or less, preferably 1500 ppm or less, and more preferably lOOOppm or less. However, simply reducing the amount of oxygen reduces the oxide phase that had the effect of suppressing grain growth, and grain growth easily occurs in the process of obtaining a sufficient density increase during sintering. Thus, in the present invention, a predetermined amount of Zr, which has an effect of suppressing abnormal growth of crystal grains during the sintering process, is contained in the RTB-based rare earth permanent magnet.
  • the RTB rare earth permanent magnet of the present invention has a Co of 4 wt% or less (not including 0), preferably 0.1 to 2.0 wt%, and more preferably 0.3 to 1.0 wt%. contains. Co forms the same phase as Fe, but has the effect of improving the Curie temperature and improving the corrosion resistance of the grain boundary phase.
  • the rare earth permanent magnet according to the present invention is formed by using an alloy mainly composed of the R 2 T 14 B phase (low R alloy) and an alloy containing more R than the low R alloy (high R alloy). The manufacturing method will be described.
  • a low R alloy and a high R alloy are obtained by strip-casting a raw metal in a vacuum or an inert gas, preferably in an Ar atmosphere.
  • care must be taken to prevent the Zr-rich product from being formed in the R 2 Ti 4 B phase in the obtained strip, particularly in the low R alloy strip.
  • the peripheral speed of the cooling roll is set in a range of 1.0 to 1.8 m / s. Desirable cooling port—The peripheral speed of the pipe is 1.2 to: 1.5 m / s.
  • a characteristic feature of the present embodiment is that Zr is added from a low R alloy. This is because the addition of Zr from a low-R alloy in which a Zr-rich product does not occur in the R 2 T 14 B phase as described in the section This is because a Zr-rich product can be present in the R 2 T 14 B phase of the rare-earth permanent magnet.
  • Low R alloys can contain Cu and A1 in addition to rare earth elements, Fe, Co and B.
  • the high-R alloy can contain Cu and A1 in addition to the rare earth elements, Fe, Co, and B.
  • the grinding process includes a coarse grinding process and a fine grinding process.
  • the raw material alloy is coarsely pulverized to a particle size of about several hundred m. It is desirable that coarse grinding be performed in an inert gas atmosphere using a stamp mill, jaw crusher, brown mill, or the like. In order to improve the coarse pulverizability, it is effective to perform coarse graining after absorbing hydrogen. Also, after performing hydrogen storage, hydrogen It can be discharged and further coarsely crushed.
  • the process proceeds to the fine pulverization step.
  • fine pulverization a jet mill is mainly used, and coarsely pulverized powder having a particle size of about several hundred ⁇ m is pulverized until the average particle size becomes 3 to 5 ⁇ . Jet mills release high-pressure inert gas (for example, nitrogen gas) from a narrow nozzle to generate a high-speed gas flow, accelerate the coarse powder by this high-speed gas flow, collide the coarse powder, and target Alternatively, it is a method of crushing by generating collision with the container wall.
  • high-pressure inert gas for example, nitrogen gas
  • the finely grounded low R alloy powder and the high R alloy powder are mixed in a nitrogen atmosphere.
  • the mixing ratio of the low R alloy powder and the high R alloy powder should be about 80:20 to 97: 3 by weight.
  • the mixing ratio may be about 80:20 to 97: 3 by weight.
  • a mixed powder composed of a low R alloy powder and a high R alloy powder is filled in a mold held by an electromagnet, and is formed in a magnetic field with its crystal axes oriented by applying a magnetic field.
  • This molding in a magnetic field is performed at a pressure of about 0.7 to 1.5 t / cm 2 in a magnetic field of 12.0 to 17.0 kOe.
  • the compact After compacting in a magnetic field, the compact is sintered in a vacuum or inert gas atmosphere.
  • the sintering temperature needs to be adjusted according to various conditions such as the composition, grinding method, difference in particle size and particle size distribution, etc., but sintering may be performed at 1000 to 100 ° C for 1 to 5 hours.
  • a Zr-rich product is generated in the R 2 T 14 B phase in this sintering step.
  • the mechanism by which Zr-rich products that are not present at the low R alloy stage are formed after sintering is evident, but solid solution in the R 2 T 14 B phase occurs at the low R alloy stage.
  • Zr that has been deposited may precipitate in the R 2 Ti 4 B phase during the sintering process.
  • the obtained sintered body can be subjected to an aging treatment.
  • Aging is important in controlling coercivity.
  • the aging process is performed in two stages, it is effective to maintain a predetermined time at around 800 ° C and around 600 ° C. Around 800 ° C
  • the heat treatment is performed after sintering, the coercive force increases, which is particularly effective in the mixing method.
  • the coercive force is greatly increased by heat treatment near 600 ° C., when aging is performed in one stage, it is preferable to perform aging near 600 ° C. (Example)
  • R_T—B based rare earth permanent magnets were manufactured by the following manufacturing process.
  • a raw material alloy (strip) having the composition and thickness shown in FIG. 1 was produced by a strip casting method.
  • the roll peripheral speed was 1. SmZs for the low R alloy and 0.6 mZs for the high R alloy. However, for the low R alloy according to Comparative Example 3 in FIG. 1, the roll peripheral speed was set to 0.6 mZs.
  • the thickness of the alloy is the average value of the thicknesses of 50 strips.
  • the low-R alloy according to Example 1 in FIG. 1 did not contain a Zr-rich product (hereinafter referred to as “in-phase product”) in the R 2 T 14 B phase. In the low R alloy according to Example 3, it was confirmed that the in-phase product was present in the R 2 Ti 4 B phase.
  • Example 1 Before pulverization, zinc stearate was added in an amount of 0.05 wt%, and the combination of Example 1 and Comparative Examples 1 to 3 shown in FIG. For 30 minutes. Note that any of Example 1, Comparative Examples 1 to 3 was used. Also, the mixing ratio of low R alloy to high R alloy is 90:10.
  • the obtained fine powder was compacted in a magnetic field of 15.k Oe at a pressure of 1.2 tZcm 2 to obtain a compact.
  • This compact was sintered at 1070 ° C. for 4 hours in a vacuum and then rapidly cooled. Next, the obtained sintered body was subjected to two-stage aging at 800 ° C for 1 hour and 550 ° C for 2.5 hours (both in an Ar atmosphere).
  • the magnetic properties of the obtained permanent magnet were measured with a BH tracer. The results are shown in Figs.
  • Br indicates the residual magnetic flux density
  • He J indicates the coercive force
  • Hk / Hc J indicates the squareness ratio.
  • the squareness ratio (Hk / Hc J) is an index of magnet performance, and indicates the degree of angularity in the second quadrant of the magnetic hysteresis loop.
  • Hk is the external magnetic field strength when the magnetic flux density becomes 90% of the residual magnetic flux density in the second quadrant of the magnetic hysteresis loop.
  • ⁇ is shown for products in which in-phase products were confirmed, and X is given for products which were not confirmed.
  • the product When subjected to a milling process in this state, the product results to be separated from the R 2 T 14 B phase, the product is a R 2 T 14 B phase without being included in the R 2 T 14 B Aiuchi Exists independently. Therefore, it is considered that the RTB-based rare earth permanent magnet according to Comparative Example 3 contains a Zr-rich product only in the grain boundary phase even after the sintering process.
  • a TEM observation was conducted on a single T—B-based rare earth permanent magnet having a Zr power of 10 wt% and a Zr power according to Example 1.
  • the observation results are shown in Figs.
  • Fig. 6 is a TEM photograph of a sample with a Zr content of 0.10 wt%
  • Fig. 7 is the product present in the sample and the EDS (Energy Dispersiveon X) of the R 2 T 14 B phase in the sample.
  • -ray Fluorescence Spectroscopymeter (profile dispersive X-ray spectroscopy) Profile
  • Fig. 8 is a TEM high-resolution photograph of the sample. As shown in FIG.
  • an in-phase product having a large axial ratio can be confirmed in the R 2 T 14 B phase.
  • This product has a plate-like or needle-like form. Since FIG. 6 shows the cross section of the sample, it is difficult to specify whether the in-phase product is plate-shaped or needle-shaped.
  • the companion product has a length of several 100 nm and a width of several nm to 15 nm. The detailed chemical composition of this in-phase product is unclear. From Fig. 7 (a), it can be confirmed that this in-phase product is at least rich in Zr. Also, the observation results of other samples show that the axial ratio is large.
  • Example 1 In addition to the in-phase products, amorphous and circular in-phase products can be observed as shown in FIGS. 9 and 10.
  • Example 1 As a result of observing 20 crystal grains (R 2 T 14 B phase), an in-phase product was observed in 6 crystal grains. In contrast, in Comparative Example 2, no in-phase product was observed for all 20 crystal grains (R 2 T 14 B phase).
  • the lower part of Fig. 11 (a) shows the Zr mapping result of the sample of Example 1 having a Zr content of 0.10 wt% by using an EPMA (Electron Probe Micro Analyzer).
  • the upper part of Fig. 11 ( a ) shows the composition image of the same field of view as the Zr mapping result shown in the lower part of Fig. 11 (a).
  • the lower part of Fig. 11 (b) shows the results of Zr mapping by EPMA of the sample of Comparative Example 2 having a Zr content of 0.10 wt%.
  • the upper part of Fig. 11 (b) shows the composition image in the same field of view as the Zr matting result shown in the lower part of Fig. 11 (b).
  • FIG. 11 (a) shows that in Example 1, the presence of the Zr-rich R 2 T 14 B phase and the presence of Zr also in the grain boundary phase were observed. Understand. On the other hand, from FIG. 11 (b), the R 2 T 14 B phase rich in Zr was not confirmed in Comparative Example 2, and Zr was present only in the grain boundary phase.
  • the first step was performed except that each was sintered for 4 hours at a temperature range of 1 ° C to 1090 ° C.
  • An RTB rare earth permanent magnet was obtained in the same manner as in the example.
  • the magnetic properties of the obtained permanent magnet were measured in the same manner as in the first example.
  • Fig. 12 shows the results.
  • FIGS. 13 to 15 show the change in the magnetic properties with respect to the sintering temperature.
  • Fig. 16 shows the magnetic properties at each sintering temperature plotted as the squareness ratio (HkZHcJ) with respect to the residual magnetic flux density (Br).
  • Example 2 in a sintering temperature range of 10.30 to 90 ° C, a residual magnetic flux density (Br) of 13.9 kG or more, 1 A coercive force (HcJ) of 3.0 k ⁇ e or more and a squareness ratio (HkZHcJ) of 95% or more can be obtained.
  • Br residual magnetic flux density
  • HcJ coercive force
  • HkZHcJ squareness ratio
  • sample D which has a greater amount of Dy than sample A
  • the residual magnetic flux density (Br) of 13.5 kG or more and the coercive force (He of 15.5 kOe or more) in the temperature range of 1030 to 1070 ° C. J) and a squareness ratio (HkZHc J) of 95% or more can be obtained.
  • HkZHc J squareness ratio
  • the presence of Zr-rich products in the R 2 T 14 B phase that constitutes the main phase of the R—T—B rare earth permanent magnet minimizes the deterioration of magnetic properties. It is possible to suppress grain growth while suppressing. Further, according to the present invention, since a sintering temperature range of 40 ° C. or more can be secured, even when a large sintering furnace in which heating temperature unevenness is likely to occur is used, stable and high magnetic properties are obtained. R—T—B rare earth permanent magnet Easily obtainable c

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Abstract

An R-T-B based rare earth element permanent magnet which comprises a sintered product having a main phase comprising an R2T14B phase, where R represents one or more rare elements including Y and T represents one or more transition metal elements comprising Fe or Fe and Co, and a grain boundary phase containing R in a content more than that in the main phase, wherein a product being rich in Zr and having the form of a plate or a needle is present in the R2T14B phase. The R-T-B based rare earth element permanent magnet containing the above allows the suppression of the growth of grains in combination of the minimization of the lowering of magnetic characteristics, and also allows the improvement of the width of sintering temperature.

Description

明 細 書 R-T-B系希土類永久磁石 技術分野  Description R-T-B rare earth permanent magnets Technical field
本発明は、 R (Rは希土類元素の 1種又は 2種以上、 但し希土類元素は Yを 含む概念である） 、 T (Tは F e又は F e及ぴ C oを必須とする少なくとも 1 種以上の遷移金属元素） 及び B (ホウ素） を主成分とする R— T一 B系希土類 永久磁石に関する。 . 背景技術  In the present invention, R (R is one or more rare earth elements, but the rare earth element is a concept including Y), T (T is Fe or at least one element in which Fe and Co are essential) The present invention relates to R-T-B rare earth permanent magnets containing the above transition metal elements) and B (boron) as main components. Background technology
希土類永久磁石の中でも R— T一 B系希土類永久磁石は、 磁気特性に優れて いること、 主成分である Ndが資源的に豊富で比較的安価であることから、 需 要は年々、 増大している。  Among Rare Earth Permanent Magnets, R-T-B Rare Earth Permanent Magnets are increasing in demand year by year due to their excellent magnetic properties, and the abundant resource of Nd, which is a major component, and their relatively low cost. ing.
R— T_B系希土類永久磁石の磁気特性を向上するための研究開発も精力的 に行われている。 例えば、 特開平 1_219143号公報では、 R— T— B系 希土類永久磁石に 0. 02〜0. 5 a t%の Cuを添加することにより、 磁気特 性が向上し、 熱処理条件も改善されることが報告されている。 しかしながら、 特開平 1一 219143号公報に記載の方法は、 高性能磁石に要求されるよう な高磁気特性、 具体的には高い保磁力 （He J) 及び残留磁束密度 （B r) を 得るには不十分であった。  R-T_B rare earth permanent magnets are also being actively researched and developed to improve their magnetic properties. For example, Japanese Patent Application Laid-Open No. H1_219143 discloses that adding 0.02 to 0.5 at% of Cu to an R-T-B rare-earth permanent magnet improves magnetic properties and heat treatment conditions. Have been reported. However, the method described in Japanese Patent Application Laid-Open No. 11-219143 requires high magnetic properties required for high-performance magnets, specifically, high coercive force (He J) and residual magnetic flux density (Br). Was inadequate.
ここで、 焼結で得られる R— T一 B系希土類永久磁石の磁気特性は焼結温度 に依存するところがある。 その一方、 工業的生産規模においては焼結炉内の全 域で加熱温度を均一にすることは困難である。 したがって、 R— T一 B系希土 類永久磁石において、 焼結温度が変動しても所望する磁気特性を得ることが要 求される。 ここで、 所望する磁気特性を得ることのできる温度範囲を焼結温度 幅とレヽぅことにする。  Here, the magnetic properties of the RTB-based rare earth permanent magnets obtained by sintering sometimes depend on the sintering temperature. On the other hand, on an industrial production scale, it is difficult to make the heating temperature uniform throughout the sintering furnace. Therefore, it is required that the RTB-based rare earth permanent magnet obtain desired magnetic properties even when the sintering temperature varies. Here, the temperature range in which the desired magnetic properties can be obtained is defined as the sintering temperature range.
R-T-B系希土類永久磁石をさらに高性能なものにするためには、 合金中 の酸素量を低下させることが必要である。 しかし、 合金中の酸素量を低下させ ると焼結工程において異常粒成長が起こりやすく、 角形比が低下する。 合金中 の酸素が形成している酸化物が結晶粒の成長を抑制しているためである。 To make RTB-based rare earth permanent magnets even more efficient, It is necessary to reduce the amount of oxygen in the water. However, when the amount of oxygen in the alloy is reduced, abnormal grain growth tends to occur in the sintering process, and the squareness ratio is reduced. This is because the oxide formed by oxygen in the alloy suppresses the growth of crystal grains.
そこで磁気特性を向上する手段として、 Cuを含有する R— T— B系希土類 永久磁石に新たな元素を添加する方法が検討されている。 特開 2000— 23 41 51号公報では、 高い保磁力及び残留磁束密度を得るために、 Z r及びノ 又は C rを添加する報告がなされている。  Therefore, as a means of improving the magnetic properties, a method of adding a new element to an R—T—B rare earth permanent magnet containing Cu is being studied. Japanese Patent Application Laid-Open No. 2000-234151 reports that Zr and / or Cr are added in order to obtain a high coercive force and a high residual magnetic flux density.
同様に特開 2002-7571 7号公報では、 C o、 A l、 Cu、 さらに Z r、 Nb又は H f を含有する R— T— B系希土類永久磁石中に微細な Z r B化 合物、 Nb B化合物又は H f B化合物 （以下、 M— B化合物） を均一に分散し て析出させることにより、 焼結過程における粒成長を抑制し、 磁気特性と焼結 温度幅を改善する報告がなされている。  Similarly, Japanese Patent Application Laid-Open No. 2002-57177 discloses that a fine ZrB compound is contained in an R—T—B-based rare earth permanent magnet containing Co, Al, Cu, and further Zr, Nb, or Hf. It has been reported that by uniformly dispersing and precipitating NbB compounds or HfB compounds (hereinafter referred to as MB compounds), the grain growth during the sintering process is suppressed, and the magnetic properties and the sintering temperature range are improved. Has been done.
特開 2002— 7571 7号公報によれば、 M— B化合物を分散'析出するこ とによって焼結温度幅が拡大されている。 しかしながら、特開 2002— 757 1 7号公報に開示される実施例 3— 1では焼結温度幅が 20 °C程度と、狭い。 よ つて、量産炉などで高い磁気特性を得るには、 さらに焼結温度幅を広げることが 望ましい。 また十分広い焼結温度幅を得るためには、 Z r添加量を増やすことが 有効である。 ところが、 Z r添加量の増大にともなって残留磁束密度は低下し、 本来目的とする高特性は得られない。  According to Japanese Patent Application Laid-Open No. 2002-75717, the sintering temperature range is expanded by dispersing and precipitating the MB compound. However, in Example 3-1 disclosed in Japanese Patent Application Laid-Open No. 2002-75717, the sintering temperature range is as narrow as about 20 ° C. Therefore, in order to obtain high magnetic properties in mass production furnaces, it is desirable to further increase the sintering temperature range. In order to obtain a sufficiently wide sintering temperature range, it is effective to increase the amount of added Zr. However, as the amount of added Zr increases, the residual magnetic flux density decreases, and the originally desired high characteristics cannot be obtained.
そこで本発明は、 磁気特性の低下を最小限に抑えつつ粒成長を抑制し、 かつ 焼結温度幅をさらに改善できる R— T一 B系希土類永久磁石を提供することを 目白勺とする。 発明の開示  Accordingly, an object of the present invention is to provide an RTB-based rare earth permanent magnet capable of suppressing grain growth while minimizing deterioration of magnetic properties and further improving the sintering temperature range. Disclosure of the invention
本発明者は R— T-B系希土類永久磁石の主相を構成する R 2 T i 4 B相内に Z rに富む生成物が存在している場合に、 磁気特性の低下を最小限に抑えつつ 粒成長を抑制し、 かつ焼結温度幅を改善できることを知見した。 すなわち、 本 発明は、 R2T14B相 （Rは希土類元素の 1種又は 2種以上（但し希土類元素は Yを含む概念である）、 Τは F e又は F e及ぴ C oを必須とする 1種又は 2種以 上の遷移金属元素） からなる主相と、 主相より Rを多く含む粒界相とを含む焼 結体からなり、 R 2 T i 4 B相内に Z rに富む生成物が存在することを特徴とする R-T-B系希土類永久磁石を提供する。 The present inventor has found that, when a product rich in Zr is present in the R 2 Ti 4 B phase constituting the main phase of the R—TB rare earth permanent magnet, it is possible to minimize the deterioration of the magnetic properties. It has been found that grain growth can be suppressed and the sintering temperature range can be improved. That is, the present invention relates to an R 2 T 14 B phase (where R is one or more rare earth elements (however, Is a concept that includes Y), Τ is a main phase composed of one or more transition metal elements that require Fe or Fe and Co, and a grain boundary that contains more R than the main phase. The present invention provides an RTB-based rare earth permanent magnet comprising a sintered body containing a phase and a Zr-rich product in an R 2 Ti 4 B phase.
本発明の R— T— B系希土類永久磁石において、 Z rに富む生成物は、 板状 又は針状の形態を有している。  In the RTB-based rare earth permanent magnet of the present invention, the product rich in Zr has a plate-like or needle-like form.
本発明の R -T-B系希土類永久磁石において、 焼結体中に含まれる酸素量 が 2 0 0 0 p pm以下であることが望ましい。 R2T14B相内に Z rに富む生成 物が存在することによる粒成長の抑制及び焼結温度幅の拡大という効果は、 焼 結体中に含まれる酸素量が 2 0 0 0 p pm以下と低酸素量の場合に顕著となる からである。 In the R-TB rare earth permanent magnet of the present invention, it is desirable that the amount of oxygen contained in the sintered body is not more than 2000 ppm. The effect of suppressing grain growth and expanding the sintering temperature range due to the presence of Zr-rich products in the R 2 T 14 B phase is due to the fact that the amount of oxygen contained in the sintered body is 200 ppm This is because it becomes remarkable when the oxygen content is as follows.
本発明の R— T— B系希土類永久磁石において、 R : 2 8〜3 3 w t %、 B ： 0. 5〜1. 5 w t %、 A l : 0. 0 3〜0. 3 w t %、 C u : 0. 3 w t %以下（ 0 を含まず）、 Z r ： 0. 0 5〜 0. 2 w t %、 C o ： 4 w t %以下 （ 0を含まず）、 残部実質的に F eからなる組成とすることが望ましい。  In the RTB rare earth permanent magnet of the present invention, R: 28 to 33 wt%, B: 0.5 to 1.5 wt%, Al: 0.03 to 0.3 wt%, Cu: 0.3 wt% or less (excluding 0), Zr: 0.05 to 0.2 wt%, Co: 4 wt% or less (excluding 0), balance substantially Fe It is desirable to have a composition consisting of
また本発明の R— T— B系希土類永久磁石において、 Z rを 0. 1〜0. 1 5 w t %の範囲内で含有させることがより望ましい。 図面の簡単な説明  Further, in the RTB-based rare earth permanent magnet of the present invention, it is more desirable that Zr be contained in the range of 0.1 to 0.15 wt%. BRIEF DESCRIPTION OF THE FIGURES
第 1図は第 1実施例で用いた低 R合金及び高 R合金の組合せ並びに得られた 永久磁石の組成を示す図表、 第 2図は第 1実施例で得られた永久磁石の磁気特 性を示す図表、 第 3図は第 1実施例で得られた永久磁石の添加元素 M (Z r或 いは T i ) 量と残留磁束密度 （B r) との関係を示すグラフ、 第 4図は第 1実 施例で得られた永久磁石の添加元素 M (Z r或いは T i ) 量と保磁力 （H e J) との関係を示すグラフ、 第 5図は第 1実施例で得られた永久磁石の添加元素 M (2 1"或ぃは丁 1 ) 量と角形比 （HkZH c J) との関係を示すグラフ、 第 6 図は実施例 1の試料（Z r量が 0. 1 0 w t %の試料） の T EM (Transmission Electron Microscope：透過型電子顕微鏡） 写真、 第 7図 （ a ) は実施例 1の試 料 （Z r量が 0. 1 0 ^^セ％の試料） に存在する生成物の ED S (Energy Dispersiveon X-ray Fluorescence Spectroscopymeter： ェ不ノレ51 r分散型 泉分 析装置分光法） プロファイルを示す図、 第 7図 （b) は実施例 1の試料 （Z r 量が 0. 10w t%の試料） における R2T14B相の ED Sプロファイルを示す 図、 第 8図は実施例 1の試料 （∑ 1：量が0. 10w t%の試料） の TEM高分 解能写真、 第 9図は実施例 1の試料 （ Z r量が 0. 10 w t %の試料） の T E M写真、 第 10図は実施例 1の試料 （ Z r量が 0. 10 w t %の試料） の T E M写真、 第 1 1図 （ a ) は実施例 1の試料 （Z r量が 0. 10 w t %の試料） の E PMA (Electron Probe Micro Analyzer：電子 ,镍マイクロアナライザ） に よる Z rマッピング結果を示す写真 （下段） 及び Z rマッピング結果 （下段） と同一視野の組成像を示す写真 （上段）、 第 1 1図 （b) は比較例 2の試料 （Z r量が 0. 10w t%の試料） の EPMAによる Z rマッピング結果を示す写 真（下段）及び Z rマッピング結果（下段） と同一視野の組成像を示す写真 （上 段)、 第 1 2図は第 2実施例で得られた永久磁石の磁気特性を示す図表、 第 1 3 図は第 2実施例における焼結温度と残留磁束密度（ B r )の関係を示すグラフ、 第 14図は第 2実施例における焼結温度と保磁力 （Hc J) の関係を示すダラ フ、 第 1 5図は第 2実施例における焼結温度と角形比 （HkZHc J) の関係 を示すグラフ、 第 16図は第 2実施例において、 各焼結温度における残留磁束 密度 （B r) と角形比 （Hk/Hc J) を対応させたグラフ、 第 17図は第 3 実施例で用いた低 R合金及び高 R合金の組合せ並びに得られた永久磁石の組成 を示す図表、第 18図は第 3実施例で得られた永久磁石の磁気特性を示す図表、 第 19図は第 4実施例で用いた低 R合金及び高 R合金の組合せ並びに得られた 永久磁石の組成を示す図表、 第 20図は第 4実施例で得られた永久磁石の磁気 特性を示す図表である。 発明を実施するための最良の形態 Fig. 1 is a table showing the combination of the low R alloy and the high R alloy used in the first embodiment and the composition of the obtained permanent magnet. Fig. 2 is the magnetic characteristic of the permanent magnet obtained in the first embodiment. FIG. 3 is a graph showing the relationship between the amount of additive element M (Zr or Ti) of the permanent magnet obtained in the first embodiment and the residual magnetic flux density (Br). Is a graph showing the relationship between the amount of additive element M (Zr or Ti) of the permanent magnet obtained in the first embodiment and the coercive force (H e J), and FIG. FIG. 6 is a graph showing the relationship between the added element M (2 1 "or 1) and the squareness ratio (HkZH c J) of the permanent magnet, and FIG. 6 shows the sample of Example 1 (Zr amount 0.1 A transmission electron microscope (TEM) photograph of a 0 wt% sample) is shown in FIG. 7 (a). Charge (Z r weight 0.1 0 ^^ Se% of the sample) present in the product of ED S: the (Energy Dispersiveon X-ray Fluorescence Spectroscopymeter E non Honoré 51 r distributed Izumi analysis apparatus Spectroscopy) profiles FIG. 7 (b) shows the EDS profile of the R 2 T 14 B phase in the sample of Example 1 (sample having a Zr content of 0.10 wt%), and FIG. TEM high resolution photo of the sample (∑1: sample with 0.10 wt%), FIG. 9 is a TEM photo of the sample of Example 1 (sample with 0.10 wt% of Zr), Fig. 10 is a TEM photograph of the sample of Example 1 (a sample having a Zr content of 0.10 wt%), and Fig. 11 (a) is a sample of the sample of Example 1 (a sample having a Zr content of 0.10 wt%). A photograph showing the Zr mapping result (lower) and a composition image of the same field of view as the Zr mapping result (lower) by EPMA (Electron Probe Micro Analyzer) of the sample Fig. 11 (b) Photograph showing the Zr mapping result (lower row) of the sample of Comparative Example 2 (sample having a Zr content of 0.10 wt%) by EPMA (lower row), and a photo showing the composition image of the same field of view as the Zr mapping result (lower row) ( Fig. 12 is a table showing the magnetic properties of the permanent magnet obtained in the second embodiment, and Fig. 13 is a graph showing the relationship between the sintering temperature and the residual magnetic flux density (B r) in the second embodiment. FIG. 14 is a graph showing the relationship between the sintering temperature and the coercive force (Hc J) in the second embodiment. FIG. 15 is a graph showing the relationship between the sintering temperature and the squareness ratio (HkZHc J) in the second embodiment. Fig. 16 is a graph showing the relationship, Fig. 16 is a graph showing the relationship between the residual magnetic flux density (Br) and the squareness ratio (Hk / Hc J) at each sintering temperature in the second embodiment, and Fig. 17 is the third embodiment. Fig. 18 is a table showing the combination of low R alloy and high R alloy used in the above and the composition of the obtained permanent magnet.Fig. 18 shows the magnetic properties of the permanent magnet obtained in the third embodiment. FIG. 19 is a chart showing the combination of the low R alloy and the high R alloy used in the fourth embodiment and the composition of the obtained permanent magnet, and FIG. 20 is a permanent magnet obtained in the fourth embodiment. 5 is a table showing the magnetic characteristics of FIG. BEST MODE FOR CARRYING OUT THE INVENTION
以下に本発明の実施の形態について説明する t T describing embodiments of the present invention are described below
ぐ組織 > 本発明によって得られる希土類永久磁石は、 よく知られているように、 R2T i 4 B相 （Rは希土類元素の 1種又は 2種以上 （但し希土類元素は Yを含む概念 である）、 Tは F e又は F e及び C oを必須とする遷移金属元素の 1種又は 2種 以上） からなる主相と、 この主相より Rを多く含む粒界相とを少なくとも含ん でいる。本発明は、 この R2T14B相内に Z rに富む生成物が存在していること を特徴としている。 この生成物が存在している R— T— B系希土類永久磁石は、 磁気特性の低下を最小限に抑えつつ粒成長を抑制し、 かつ広い焼結温度幅を得 ることができる。 この生成物は、 R2T14B相内に存在していることが必要であ るが、全ての R2T14B相内に存在することを要件とするものでない。 また、 こ の生成物は粒界相に存在していても良い。 但し、 粒界相にのみ Z rに富む生成 物が存在している場合には、 本発明の効果を享受することはできない。 Organization> As is well known, the rare earth permanent magnet obtained by the present invention has an R 2 T i 4 B phase (R is one or more rare earth elements (where the rare earth element is a concept including Y), T includes at least a main phase composed of Fe or one or more of transition metal elements in which Fe and Co are essential) and a grain boundary phase containing more R than the main phase. The present invention is characterized in that a Zr-rich product is present in the R 2 T 14 B phase. The R-T-B rare-earth permanent magnet in which this product exists can suppress grain growth while minimizing deterioration of magnetic properties, and can obtain a wide sintering temperature range. This product must be present in the R 2 T 14 B phase, but need not be present in all R 2 T 14 B phases. This product may be present in the grain boundary phase. However, when the product rich in Zr is present only in the grain boundary phase, the effects of the present invention cannot be enjoyed.
R_T— B系希土類永久磁石において、 R2T14B相内に生成物を形成する添 加元素として、 従来から T iが知られている （例えば】. Appl. Phys. 69 (1991) 6055)。 本発明者は Z r及び T iを添加することによって R 2 T i 4 B相内に生成 物を形成すると、焼結温度幅の拡大に有効であるとの知見を得た。 ここで、 Z r の場合には、焼結温度幅の拡大という効果を十分に発揮する量を添カ卩しても、磁 気特性、 具体的には残留磁束密度 （B r) の低下をほとんど起こすことがなレ、。 一方、 T iの場合は、焼結温度幅の拡大という効果を十分に発揮する量を添加す ると、 残留磁束密度 （B r) の低下が著しく、 実施上好ましくないことが明らか となった。 以上のように、 生成物の組成を Z rに富む組成とすることにより、 高 特性の永久磁石が、広い焼結温度幅において安定して製造することが可能となる。 In R_T—B-based rare earth permanent magnets, Ti has been known as an additional element that forms a product in the R 2 T 14 B phase (for example, Appl. Phys. 69 (1991) 6055). . The present inventor has found that forming a product in the R 2 T i 4 B phase by adding Zr and T i is effective for increasing the sintering temperature range. Here, in the case of Zr, the magnetic properties, specifically the residual magnetic flux density (Br), are reduced even if the amount of addition is sufficient to exert the effect of increasing the sintering temperature range. I can hardly get up. On the other hand, in the case of Ti, it was clarified that, when an amount sufficient to exert the effect of increasing the sintering temperature range was added, the residual magnetic flux density (Br) was significantly reduced, which was not preferable in practice. . As described above, by setting the composition of the product to a composition rich in Zr, it becomes possible to stably produce a high-performance permanent magnet over a wide sintering temperature range.
Z rに富む生成物を R2T14B相内に存在させるためには、製法上のいくつか の要件があることを本発明者は確認した。 本発明による永久磁石の製造方法の 一連の工程については後述するとして、 ここでは、 Z rに富む生成物が尺21\ 4B相内に存在するための要件について説明する。 The present inventor has confirmed that there are some manufacturing requirements for the Zr-rich product to be present in the R 2 T 14 B phase. As will be described later series of steps of a method of manufacturing a permanent magnet according to the present invention, it will be described here requirements for products rich in Z r is present in the scale 2 1 \ 4 B Aiuchi.
R_T— B系希土類永久磁石の製造方法としては、 所望する組成と一致する 単一の合金を出発原料とする方法 （以下、 単一法という） と、 異なる組成を有 する複数の合金を出発原料とする方法 （以下、 混合法という） の二つが存在す る。 混合法は、 典型的には、 R2T14B相を主体とする合金 （低 R合金） と、 低 R合金より Rを多く含む合金 （高 R合金） とを出発原料とする。 R_T-B rare earth permanent magnets can be produced by using a single alloy that matches the desired composition as the starting material (hereinafter referred to as the single method), or by using multiple alloys having different compositions as the starting material. (Hereinafter referred to as the “mixing method”) You. The mixing method typically uses an alloy mainly composed of the R 2 T 14 B phase (low R alloy) and an alloy containing more R than the low R alloy (high R alloy) as starting materials.
本発明者は、 低 R合金及ぴ高 R合金のいずれかに Z rを含有させて R— T一 B系希土類永久磁石を得た。 その結果、 低 R合金に Z rを含有させて永久磁石 を作製した場合には、 Z rに富む生成物が R2T14B相内に存在することを確認 した。 一方、 高 R合金に Z rを含有させた場合には Z rに富む生成物が RsT^ 4 B相内に存在しないことを確認した。 The present inventor obtained an RT—B-based rare earth permanent magnet by adding Zr to either the low R alloy or the high R alloy. As a result, it was confirmed that when a permanent magnet was prepared by adding Zr to a low-R alloy, a Zr-rich product was present in the R 2 T 14 B phase. On the other hand, if it is contained Z r on the high R alloys was confirmed that the product-rich Z r is not present in RsT ^ 4 B Aiuchi.
また、 低 R合金に Z rを含有させた場合であっても、 低 R合金の段階で Z r に富む生成物が R 2 T i 4 B相内に存在していると、焼結後においては Z rに富む 生成物は焼結組織中の三重点にある Rリッチ相 （粒界相） に存在するが、 R2T 14B相内には Z rに富む生成物を確認することができなかった。 したがって、 R— T一 B系希土類永久磁石の R2T14B相内に Z rに富む生成物を存在させ. るためには、原料合金の段階で R2T14B相内に Z rに富む生成物を存在させな いことが重要である。 Even when Zr is contained in the low R alloy, if a product rich in Zr is present in the R 2 Ti 4 B phase at the stage of the low R alloy, The Zr-rich product exists in the R-rich phase (grain boundary phase) at the triple point in the sintered structure, but the Zr-rich product can be confirmed in the R 2 T 14 B phase. could not. Therefore, R- T foremost B system R 2 T 14 B rare earth permanent magnet Aiuchi the presence of a product enriched in Z r. The order, in the raw material alloy stage R 2 T 14 B Aiuchi to Z r It is important not to have high-enriched products.
そのためには、 原料合金の製造方法に配慮する必要がある。 低 R合金をスト リップキャスト法で作製する場合には、 冷却ロールの周速を制御する必要があ る。 冷却ロールの周速が遅い場合には、 一 F eの析出を招くととも.に、 Z r に富む生成物が低 R合金の R 2 T i 4 B相内に生成される。本発明者の検討による と、 冷却ロールの周速が 1. 0〜1. 8m/sの範囲にあれば、 Z rに富む生 成物が R2T14B相内に存在しない低 R合金を得ることができる。そしてこの低 R合金を用いることにより、 高い磁気特性の永久磁石を得ることができる。 For that purpose, it is necessary to consider the production method of the raw material alloy. When manufacturing low R alloys by the strip casting method, it is necessary to control the peripheral speed of the cooling roll. If the peripheral speed of the cooling roll is low, precipitation of one Fe is caused, and a product rich in Zr is generated in the R 2 Ti 4 B phase of the low R alloy. According to the study of the present inventor, if the peripheral speed of the chill roll is in the range of 1.0 to 1.8 m / s, a low R alloy in which Zr-rich products do not exist in the R 2 T 14 B phase Can be obtained. By using this low R alloy, a permanent magnet having high magnetic properties can be obtained.
また、 Z rに富む生成物が R2T14B相内に存在しない低 R合金を得ても、 こ れに熱処理を加え、 それを原料合金として用いることは、本発明にとって望まし くない。低 R合金の組織を改変するような温度域（およそ 700°C以上） で熱処 理を加えることにより、 低 R合金の R2T14B相内に Z rに富む生成物が生成さ れてしまうからである。 Further, even if a low-R alloy in which a Zr-rich product is not present in the R 2 T 14 B phase is obtained, it is not desirable for the present invention to apply a heat treatment to it and use it as a raw material alloy. . Heat treatment in a temperature range that alters the structure of the low-R alloy (approximately 700 ° C or higher) produces a Zr-rich product in the R 2 T 14 B phase of the low-R alloy. It is because.
く化学組成〉  Chemical composition>
次に、 本発明による R— T一 B系希土類永久磁石の望ましい化学組成につい て説明する。 ここでいう化学組成は焼結後における化学組成をいう。 Next, the desirable chemical composition of the RTB-based rare earth permanent magnet according to the present invention will be described. Will be explained. The chemical composition here refers to the chemical composition after sintering.
本発明の希土類永久磁石は、 Rを 25〜35wt %含有する。  The rare earth permanent magnet of the present invention contains 25 to 35 wt% of R.
ここで、 Rは、 La， C e， P r , Nd, Sm， Eu， G d, Tb, Dy, H o， E r， Yb, L u及び Yからなるグループから選択される 1種又は 2種以上 である。 Rの量が 25 wt%未満であると、 希土類永久磁石の主相となる R2T 14B相の生成が十分ではない。 このため、軟磁性を持つ α— F eなどが析出し、 保磁力が著しく低下する。 一方、 Rの量が 35 w t%を超えると主相である R2 T14B相の体積比率が低下し、 残留磁束密度が低下する。 また Rの量が 35w t%を超えると Rが酸素と反応し、含有する酸素量が増え、 これに伴い保磁力発 生に有効な Rリッチ相が減少し、保磁力の低下を招く。 したがって、 Rの量は 2 5〜35wt%とする。望ましい Rの量は 28〜33w t%、 さらに望ましい R の量は 29〜 32 w t %である。 Here, R is one or two selected from the group consisting of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu, and Y. More than species. If the amount of R is less than 25 wt%, the generation of the R 2 T 14 B phase which is the main phase of the rare earth permanent magnet is not sufficient. As a result, α-Fe with soft magnetism precipitates and the coercive force is significantly reduced. On the other hand, when the amount of R exceeds 35 wt%, the volume ratio of the main phase, R 2 T 14 B phase, decreases, and the residual magnetic flux density decreases. If the amount of R exceeds 35 wt%, R reacts with oxygen, and the amount of oxygen contained increases. As a result, the R-rich phase effective for generating coercive force decreases, and the coercive force decreases. Therefore, the amount of R should be 25-35 wt%. A desirable amount of R is 28 to 33 wt%, and a more desirable amount of R is 29 to 32 wt%.
Ndは資源的に豊富で比較的安価であることから、 Rとしての主成分を Nd とすることが好ましい。 また Dyは R2T14B相の異方性磁界を増加させ、保磁 力を向上させる上で有効である。 よって、 Rとして Nd及ぴ Dyを選択し、 N d及ぴ Dyの合計を 25〜33w t%とすることが望ましい。 そして、 この範 囲において、 0 の量は0. 1〜 8 w t °/0が望ましい。 Dyは、 残留磁束密度 及び保磁力のいずれを重視するかによって上記範囲内においてその量を定める ことが望ましい。 つまり、 高い残留磁束密度を得たい場合には Dy量を 0. 1〜 3. 5wt%とし、 高い保磁力を得たい場合には Dy量を 3. 5〜 8 w t %と することが望ましい。 Since Nd is abundant in resources and relatively inexpensive, it is preferable that the main component of R be Nd. Dy is effective in increasing the anisotropic magnetic field of the R 2 T 14 B phase and improving the coercive force. Therefore, it is desirable to select Nd and Dy as R, and to make the sum of Nd and Dy 25 to 33 wt%. In this range, the amount of 0 is desirably 0.1 to 8 wt ° / 0 . The amount of Dy is desirably determined within the above range depending on which of the residual magnetic flux density and the coercive force is important. In other words, it is desirable to set the Dy amount to 0.1 to 3.5 wt% to obtain a high residual magnetic flux density, and to set the Dy amount to 3.5 to 8 wt% to obtain a high coercive force.
また、 本発明の希土類永久磁石は、 ホウ素 （B) を 0.5〜4. 5w t%含有 する。 Bが 0. 5w t%未満の場合には高い保磁力を得ることができない。 但 し、 Bが 4. 5 wt%を超えると残留磁束密度が低下する傾向がある。 したが つて、 上限を 4. 5w t%とする。 望ましい Bの量は 0. 5〜1. 5 w t %、 さ らに望ましい Bの量は 0. 8〜： 1. 2wt%である。  The rare earth permanent magnet of the present invention contains boron (B) in an amount of 0.5 to 4.5 wt%. If B is less than 0.5 wt%, a high coercive force cannot be obtained. However, when B exceeds 4.5 wt%, the residual magnetic flux density tends to decrease. Therefore, the upper limit is set to 4.5wt%. The desirable amount of B is 0.5 to 1.5 wt%, and the more desirable amount of B is 0.8 to: 1.2 wt%.
本発明の R— T— B系希土類永久磁石は、 A 1及び Cuの 1種又は 2種を 0. 02〜0.6 w t%の範囲で含有することができる。 この範囲で A 1及ぴ Cuの 1種又は 2種を含有させることにより、 得られる永久磁石の高保磁力化、 高耐 食性化、 温度特性の改善が可能となる。 A 1を添加する場合において、 望まし い A 1の量は 0.03〜0. 3 w t%、さらに望ましい A 1の量は 0.05〜0. 25wt%である。 また、 Cuを添加する場合において、 〇11の量は0. 3w t%以下 （0を含まず）、 望ましくは 0. 15w t%以下 （0を含まず）、 さら に望ましい Cuの量は 0.03〜0. 08 w t%である。 The RTB-based rare earth permanent magnet of the present invention may contain one or two of A1 and Cu in a range of 0.02 to 0.6 wt%. In this range, A1 and Cu By including one or two kinds, it is possible to increase the coercive force, the corrosion resistance, and the temperature characteristics of the obtained permanent magnet. When A1 is added, a desirable amount of A1 is 0.03 to 0.3 wt%, and a more desirable amount of A1 is 0.05 to 0.25 wt%. In addition, when Cu is added, the amount of No. 11 is 0.3 wt% or less (excluding 0), preferably 0.15 wt% or less (not including 0), and more preferably 0.03 wt% or less. ~ 0.08 wt%.
本発明の R— T一 B系希土類永久磁石は、 R 2 T i 4 B相内に Z rに富む生成物 を生成させるために、 Z rを 0.03〜0. 25 w t %含有することが望ましレ、。 R-T-B系希土類永久磁石の磁気特性向上を図るために酸素含有量を低減す る際に、 Z rは焼結過程での結晶粒の異常成長を抑制する効果を発揮し、 焼結 体の組織を均一かつ微細にする。 したがって、 Z rは酸素量が低い場合にその 効果が顕著になる。 Z rの望ましい量は 0.05〜0. 2w t%、 さらに望まし い量は 0. 1〜0. 15wt%である。 R- T one B system rare earth permanent magnet of the present invention, in order to produce a product enriched in Z r in R 2 T i 4 B Aiuchi, to contain Z r 0.03~0. 25 wt% Nozomu Masire, When reducing the oxygen content in order to improve the magnetic properties of RTB rare earth permanent magnets, Zr exerts the effect of suppressing the abnormal growth of crystal grains during the sintering process, and changes the structure of the sintered body. Make it uniform and fine. Therefore, the effect of Zr becomes remarkable when the oxygen content is low. The desirable amount of Zr is 0.05 to 0.2 wt%, and the more desirable amount is 0.1 to 0.15 wt%.
本発明の R— T— B系希土類永久磁石は、 その酸素量を 2000 pm以下 とする。 酸素量が多いと非磁性成分である酸ィヒ物相が増大して、 磁気特性を低 下させる。 そこで本発明では、 焼結体中に含まれる酸素量を、 2000 p pm 以下、 望ましくは 1 500 p p m以下、 さらに望ましくは l O O O p p m以下 とする。 但し、 単純に酸素量を低下させたのでは、 粒成長抑制効果を有してい た酸化物相が減少し、 焼結時に十分な密度上昇を得る過程で粒成長が容易に起 こる。 そこで、 本発明では、 焼結過程での結晶粒の異常成長を抑制する効果を 発揮する Z rを、 R— T— B系希土類永久磁石中に所定量含有させる。  The R—T—B-based rare earth permanent magnet of the present invention has an oxygen content of 2000 pm or less. If the amount of oxygen is large, the acid phase, which is a nonmagnetic component, increases, and the magnetic properties deteriorate. Therefore, in the present invention, the amount of oxygen contained in the sintered body is set to 2000 ppm or less, preferably 1500 ppm or less, and more preferably lOOOppm or less. However, simply reducing the amount of oxygen reduces the oxide phase that had the effect of suppressing grain growth, and grain growth easily occurs in the process of obtaining a sufficient density increase during sintering. Thus, in the present invention, a predetermined amount of Zr, which has an effect of suppressing abnormal growth of crystal grains during the sintering process, is contained in the RTB-based rare earth permanent magnet.
本発明の R— T— B系希土類永久磁石は、 C oを 4w t%以下（0を含まず）、 望ましくは 0. 1〜2.0wt%、 さらに望ましくは 0. 3〜1. 0w t%含有す る。 C oは F eと同様の相を形成するが、 キュリー温度の向上、 粒界相の耐食 性向上に効果がある。  The RTB rare earth permanent magnet of the present invention has a Co of 4 wt% or less (not including 0), preferably 0.1 to 2.0 wt%, and more preferably 0.3 to 1.0 wt%. contains. Co forms the same phase as Fe, but has the effect of improving the Curie temperature and improving the corrosion resistance of the grain boundary phase.
く製造方法 > Production method>
次に、 本発明による R— T一 B系希土類永久磁石の好適な製造方法について 説明する。 本実施の形態では、 R2T14B相を主体とする合金 （低 R合金） と、低 R合金 より Rを多く含む合金 （高 R合金） とを用いて本発明に係る希土類永久磁石を 製造する方法について示す。 Next, a preferred method for producing the RTB-based rare earth permanent magnet according to the present invention will be described. In the present embodiment, the rare earth permanent magnet according to the present invention is formed by using an alloy mainly composed of the R 2 T 14 B phase (low R alloy) and an alloy containing more R than the low R alloy (high R alloy). The manufacturing method will be described.
はじめに、 原料金属を真空又は不活性ガス、 好ましくは A r雰囲気中でスト リップキャスティングすることにより、低 R合金及び高 R合金を得る。ここで、 前述したように、 得られたストリップ、 特に低 R合金ストリップには、 Z rに 富む生成物が R 2 T i 4 B相内に生成しないように配慮する必要がある。具体的に は、 冷却ロールの周速を 1. 0〜1. 8m/ sの範囲とする。 望ましい冷却口 —ルの周速は 1. 2〜： 1. 5 m/ sである。 First, a low R alloy and a high R alloy are obtained by strip-casting a raw metal in a vacuum or an inert gas, preferably in an Ar atmosphere. Here, as described above, care must be taken to prevent the Zr-rich product from being formed in the R 2 Ti 4 B phase in the obtained strip, particularly in the low R alloy strip. Specifically, the peripheral speed of the cooling roll is set in a range of 1.0 to 1.8 m / s. Desirable cooling port—The peripheral speed of the pipe is 1.2 to: 1.5 m / s.
Z rに富む生成物が存在しない R2T14B相を有する低 R合金を得てから後 述する焼結工程までの間、当該生成物を R2T14B相内に生成させなレ、、つまり 当該 R2T14B相の形態を維持させることが本発明にとって重要である。例えば、 水素粉碎から始まる粉碎工程の前に、 低 R合金を 700°C以上に加熱保持する 熱処理を行なうことは避けることが望ましい。 この点については、 後述する第 1実施例にてさらに言及する。 Until sintering step enriched product Z r is discussed later after obtaining the low R alloys having the R 2 T 14 B phase is not present, Les such to produce the product in R 2 T 14 B Aiuchi That is, it is important for the present invention to maintain the form of the R 2 T 14 B phase. For example, it is desirable to avoid performing a heat treatment to heat and maintain the low R alloy above 700 ° C before the comminution process starting from hydrogen comminution. This point will be further described in a first embodiment described later.
本実施の形態で特徴的な事項は、 Z rを低 R合金から添加するという点であ る。 これは、 く組織〉の欄で説明したように、 Z rに富む生成物が R2T14B相 内に生じていない低 R合金から Z rを添加することにより、 R— T— B系希土 類永久磁石の R2T14B相内に Z rに富む生成物を存在させることができるか らである。 低 R合金には、 希土類元素、 F e、 Co及び Bの他に、 Cu及び A 1を含有させることができる。 また、 高 R合金には、 希土類元素、 F e、 Co 及び Bの他に、 Cu及び A 1を含有させることができる。 A characteristic feature of the present embodiment is that Zr is added from a low R alloy. This is because the addition of Zr from a low-R alloy in which a Zr-rich product does not occur in the R 2 T 14 B phase as described in the section This is because a Zr-rich product can be present in the R 2 T 14 B phase of the rare-earth permanent magnet. Low R alloys can contain Cu and A1 in addition to rare earth elements, Fe, Co and B. The high-R alloy can contain Cu and A1 in addition to the rare earth elements, Fe, Co, and B.
低 R合金及び高 R合金が作製された後、 これらの原料合金は別々に又は一緒 に粉碎される。 粉碎工程には、 粗粉碎工程と微粉砕工程とがある。 まず、 原料 合金を、 それぞれ粒径数百 m程度になるまで粗粉碎する。 粗粉碎は、 スタン プミル、 ジョークラッシャー、 ブラウンミル等を用い、 不活性ガス雰囲気中に て行なうことが望ましい。粗粉砕性を向上させるために、水素を吸蔵させた後、 粗粉碑を行なうことが効果的である。 また、 水素吸蔵を行なった後に、 水素を 放出させ、 更に粗粉砕を行なうこともできる。 After the low R and high R alloys are made, these raw alloys are milled separately or together. The grinding process includes a coarse grinding process and a fine grinding process. First, the raw material alloy is coarsely pulverized to a particle size of about several hundred m. It is desirable that coarse grinding be performed in an inert gas atmosphere using a stamp mill, jaw crusher, brown mill, or the like. In order to improve the coarse pulverizability, it is effective to perform coarse graining after absorbing hydrogen. Also, after performing hydrogen storage, hydrogen It can be discharged and further coarsely crushed.
粗粉碎工程後、微粉碎工程に移る。微粉碎は、主にジエツトミルが用いられ、 粒径数百 μ m程度の粗粉砕粉末が、平均粒径 3〜5 μπιになるまで粉砕される。 ジェットミルは、 高圧の不活性ガス (例えば窒素ガス) を狭いノズルより開放 して高速のガス流を発生させ、 この高速のガス流により粗粉砕粉末を加速し、 粗粉碎粉末同士の衝突やターグットあるいは容器壁との衝突を発生させて粉碎 する方法である。  After the coarse pulverization step, the process proceeds to the fine pulverization step. In the case of fine pulverization, a jet mill is mainly used, and coarsely pulverized powder having a particle size of about several hundred μm is pulverized until the average particle size becomes 3 to 5 μπι. Jet mills release high-pressure inert gas (for example, nitrogen gas) from a narrow nozzle to generate a high-speed gas flow, accelerate the coarse powder by this high-speed gas flow, collide the coarse powder, and target Alternatively, it is a method of crushing by generating collision with the container wall.
微粉砕工程において低 R合金及び高 R合金を別々に粉粋した場合には、 微粉 碎された低 R合金粉末及び高 R合金粉末とを窒素雰囲気中で混合する。 低 R合 金粉末及び高 R合金粉末の混合比率は、 重量比で 80 ： 20〜97 ： 3程度と すればよレ、。 同様に、 低 R合金及び高 R合金を一緒に粉砕する場合の混合比率 も重量比で 80 ： 20〜97 ： 3程度とすればよい。 微粉碎時に、 ステアリン 酸亜鉛等の添加剤を 0.01〜◦ . 3 w t %程度添加することにより、 成形時に 配向性の高い微粉を得ることができる。  When the low R alloy and the high R alloy are separately ground in the pulverization process, the finely grounded low R alloy powder and the high R alloy powder are mixed in a nitrogen atmosphere. The mixing ratio of the low R alloy powder and the high R alloy powder should be about 80:20 to 97: 3 by weight. Similarly, when the low R alloy and the high R alloy are pulverized together, the mixing ratio may be about 80:20 to 97: 3 by weight. By adding an additive such as zinc stearate at about 0.01 to about 3 wt% at the time of pulverization, fine powder having high orientation can be obtained at the time of molding.
次いで、 低 R合金粉末及び高 R合金粉末からなる混合粉末を、 電磁石に抱か れた金型内に充填し、 磁場印加によってその結晶軸を配向させた状態で磁場中 成形する。 この磁場中成形は、 12. 0〜1 7. O kOeの磁場中で、 0. 7〜 1. 5 t/cm2前後の圧力で行なえばょレ、。 Next, a mixed powder composed of a low R alloy powder and a high R alloy powder is filled in a mold held by an electromagnet, and is formed in a magnetic field with its crystal axes oriented by applying a magnetic field. This molding in a magnetic field is performed at a pressure of about 0.7 to 1.5 t / cm 2 in a magnetic field of 12.0 to 17.0 kOe.
磁場中成形後、 その成形体を真空又は不活性ガス雰囲気中で焼結する。 焼結 温度は、 組成、 粉碎方法、 粒度と粒度分布の違い等、 諸条件により調整する必 要があるが、 1000〜1 100°Cで 1〜5時間程度焼結すればよい。 本発明 では、 この焼結工程において R2T14B相内に Z rに富む生成物を生成させる。 低 R合金の段階で存在していない Z rに富む生成物が焼結後に生成されるメカ 二ズムは明らかでなレ、が、低 R合金の段階で R 2 T 14 B相内に固溶していた Z r が焼結工程中に R 2 T i 4 B相内に析出する可能 1·生がある。 After compacting in a magnetic field, the compact is sintered in a vacuum or inert gas atmosphere. The sintering temperature needs to be adjusted according to various conditions such as the composition, grinding method, difference in particle size and particle size distribution, etc., but sintering may be performed at 1000 to 100 ° C for 1 to 5 hours. In the present invention, a Zr-rich product is generated in the R 2 T 14 B phase in this sintering step. The mechanism by which Zr-rich products that are not present at the low R alloy stage are formed after sintering is evident, but solid solution in the R 2 T 14 B phase occurs at the low R alloy stage. There is a possibility that Zr that has been deposited may precipitate in the R 2 Ti 4 B phase during the sintering process.
焼結後、 得られた焼結体に時効処理を施すことができる。 時効処理は、 保磁 力を制御する上で重要である。 時効処理を 2段に分けて行なう場合には、 80 0°C近傍、 600°C近傍での所定時間の保持が有効である。 800°C近傍での 熱処理を焼結後に行なうと、 保磁力が増大するため、 混合法においては特に有 効である。 また、 6 0 0°C近傍の熱処理で保磁力が大きく増加するため、 時効 処理を 1段で行なう場合には、 6 0 0°C近傍の時効処理を施すとよい。 (実施例） After sintering, the obtained sintered body can be subjected to an aging treatment. Aging is important in controlling coercivity. When the aging process is performed in two stages, it is effective to maintain a predetermined time at around 800 ° C and around 600 ° C. Around 800 ° C When the heat treatment is performed after sintering, the coercive force increases, which is particularly effective in the mixing method. In addition, since the coercive force is greatly increased by heat treatment near 600 ° C., when aging is performed in one stage, it is preferable to perform aging near 600 ° C. (Example)
<第 1実施例〉  <First embodiment>
下記の製造工程により、 R _ T— B系希土類永久磁石を製造した。  R_T—B based rare earth permanent magnets were manufactured by the following manufacturing process.
1 ) 原料合金  1) Raw material alloy
ストリップキャスト法により、 第 1図に示す組成及ぴ厚さを有する原料合金 (ストリップ） を作製した。 ロール周速は、 低 R合金については 1. SmZs とし、 高 R合金については 0. 6mZsとした。 但し、 第 1図の比較例 3にか かる低 R合金については、 ロール周速を 0. 6mZsとした。 合金の厚みは 5 0個の铸片 （ストリップ） の厚みを測定した平均値である。 なお、 第 1図の実 施例 1にかかる低 R合金には R2T14B相内に Z rに富む生成物（以下、相内生 成物） が確認されなかったのに対し、 比較例 3にかかる低 R合金では相内生成 物が R 2 T i 4 B相内に存在することが確認された。 A raw material alloy (strip) having the composition and thickness shown in FIG. 1 was produced by a strip casting method. The roll peripheral speed was 1. SmZs for the low R alloy and 0.6 mZs for the high R alloy. However, for the low R alloy according to Comparative Example 3 in FIG. 1, the roll peripheral speed was set to 0.6 mZs. The thickness of the alloy is the average value of the thicknesses of 50 strips. The low-R alloy according to Example 1 in FIG. 1 did not contain a Zr-rich product (hereinafter referred to as “in-phase product”) in the R 2 T 14 B phase. In the low R alloy according to Example 3, it was confirmed that the in-phase product was present in the R 2 Ti 4 B phase.
2) 水素粉碎工程  2) Hydrogen grinding process
室温にて水素を吸蔵させた後、 A r雰囲気中で 6 0 0°CX 1時間の脱水素を 行なう、 水素粉砕処理を行なった。  After occlusion of hydrogen at room temperature, dehydrogenation was performed at 600 ° C. for 1 hour in an Ar atmosphere, followed by hydrogen pulverization.
高磁気特性を得るべく、 本実験では焼結体酸素量を 2 0 0 0 p p m以下に抑 えるために、 水素粉碎 （粉砕処理後の回収） から焼結 （焼結炉に投入する） ま での各工程の雰囲気を、 1 ◦ 0 p pm未満の酸素濃度に抑えてある。  In this experiment, in order to obtain high magnetic properties, in order to reduce the oxygen content of the sintered body to less than 2000 ppm, from the hydrogen grinding (recovery after pulverization) to sintering (put into the sintering furnace). The atmosphere in each step is controlled to an oxygen concentration of less than 1 ◦ 0 ppm.
3) 混合 '粉砗工程  3) Mixing process
通常、 粗粉砕と微粉砕による 2段粉砕を行っているが、 本実施例では粗粉砕 工程を省いている。  Usually, two-stage pulverization by coarse pulverization and fine pulverization is performed, but in this embodiment, the coarse pulverization step is omitted.
微粉砕を行なう前にステアリン酸亜鉛を 0. 0 5 w t %添加し、 第 1図に示 す実施例 1、 比較例 1〜比較例 3の組合せで低 R合金と高 R合金とをナウター ミキサーで 3 0分間混合した。 なお、 実施例 1、 比較例 1〜比較例 3のいずれ についても、 低 R合金と高 R合金との混合比率は 90 ： 10である。 Before pulverization, zinc stearate was added in an amount of 0.05 wt%, and the combination of Example 1 and Comparative Examples 1 to 3 shown in FIG. For 30 minutes. Note that any of Example 1, Comparative Examples 1 to 3 was used. Also, the mixing ratio of low R alloy to high R alloy is 90:10.
その後、 ジェットミルにて平均粒径 4. 8〜 5. 1 μ mまで微粉砕を行なつ た。  Then, it was pulverized with a jet mill to an average particle size of 4.8 to 5.1 μm.
4) 成形工程  4) Molding process
得られた微粉末を 15. ひ k O eの磁場中で 1.2 t Z c m2の圧力で成形を 行い、 成形体を得た。 The obtained fine powder was compacted in a magnetic field of 15.k Oe at a pressure of 1.2 tZcm 2 to obtain a compact.
5) 焼結、 時効工程  5) Sintering, aging process
この成形体を真空中において 1070°Cで 4時間焼結した後、 急冷した。 次 いで得られた焼結体に 800 °C X 1時間と 550 °C X 2. 5時間 （ともに A r 雰囲気中） の 2段時効処理を施した。  This compact was sintered at 1070 ° C. for 4 hours in a vacuum and then rapidly cooled. Next, the obtained sintered body was subjected to two-stage aging at 800 ° C for 1 hour and 550 ° C for 2.5 hours (both in an Ar atmosphere).
得られた永久磁石について B— Hトレーサにより磁気特性を測定した。その結 果を第 2図〜第 5図に示す。 なお、 第 2図〜第 5図において、 B rは残留磁束密 度、 He Jは保磁力、 「Hk/Hc J」 は角形比を示す。 角形比 (Hk/Hc J) は磁石性能の指標となるものであり、磁気ヒステリシスル一プの第 2象限におけ る角張の度合いを表す。 なお Hkは、磁気ヒステリシスループの第 2象限におい て、磁束密度が残留磁束密度の 90%になるときの外部磁界強度である。第 2図 〜第 5図において、相内生成物が確認されたものに〇を、確認されなかったもの に Xを付してある。 相内生成物の確認は、 TEM (Transmission Electron Microscope：透過型電子顕微鏡 （日本電子 （株） 製 J EM— 3010)) による 観察に基づいている。 観察試料はイオンミリング法により作製し、 R2T14B相 の C面を観察した。 なお、 得られた焼結体の化学組成は第 1図の 「焼結体組成」 の欄に示してある。 また、 比較例 3には相内生成物は確認されなかった力 粒界 相に Z rに富む生成物が確認された。 The magnetic properties of the obtained permanent magnet were measured with a BH tracer. The results are shown in Figs. In FIGS. 2 to 5, Br indicates the residual magnetic flux density, He J indicates the coercive force, and “Hk / Hc J” indicates the squareness ratio. The squareness ratio (Hk / Hc J) is an index of magnet performance, and indicates the degree of angularity in the second quadrant of the magnetic hysteresis loop. Hk is the external magnetic field strength when the magnetic flux density becomes 90% of the residual magnetic flux density in the second quadrant of the magnetic hysteresis loop. In Fig. 2 to Fig. 5, 〇 is shown for products in which in-phase products were confirmed, and X is given for products which were not confirmed. Confirmation of the in-phase product is based on observation with a TEM (Transmission Electron Microscope: JEM-3010 manufactured by JEOL Ltd.). The observation sample was prepared by the ion milling method, and the C plane of the R 2 T 14 B phase was observed. The chemical composition of the obtained sintered body is shown in the column of “Sintered body composition” in FIG. In Comparative Example 3, a product rich in Zr was confirmed in the grain boundary phase, in which no in-phase product was confirmed.
第 2図及び第 5図より、相内生成物が確認された R _ T _ B系希土類永久磁石 (実施例 1、 比較例 1 ) においては、 異常な粒成長が抑制されており、 少量の添 加元素 M ( ！^或ぃは！^) によって角形比 （HkZHc J) が改善されること がわかる。但し、第 3図に示すように添加元素 Mとして T iを選択した場合には、 残留磁束密度 （B r) の低下が著しい。 また、 相内生成物が確認されなかった R 一 T一 B系希土類永久磁石 （比較例 2、 比較例 3) においても、 0. 2w t%と 多量の Z rの添加によって角形比（Hk/Hc J)は向上するが（第 5図参照）、 やはり残留磁束密度 （B r) の低下が大きい （第 3図参照）。 以上のように、 相 内生成物の確認された R— T— B系希土類永久磁石は、残留磁束密度 （B r) の 低下を抑制しつつ、 高い角形比 （HkZHc J) を得ることができる。 From FIGS. 2 and 5, in the R_T_B-based rare earth permanent magnet (Example 1, Comparative Example 1) in which in-phase products were confirmed, abnormal grain growth was suppressed, and a small amount of It can be seen that the squareness ratio (HkZHc J) is improved by the additional element M (! ^ Or ！! ^). However, when Ti is selected as the additive element M as shown in FIG. 3, the residual magnetic flux density (B r) is significantly reduced. In addition, no in-phase product was observed. The squareness ratio (Hk / Hc J) of the 1T-1B rare earth permanent magnets (Comparative Example 2 and Comparative Example 3) is improved by adding a large amount of 0.2wt% of Zr (see Fig. 5). ), The decrease in residual magnetic flux density (Br) is also large (see Fig. 3). As described above, R-T-B based rare earth permanent magnets in which in-phase products have been confirmed can achieve a high squareness ratio (HkZHc J) while suppressing a decrease in residual magnetic flux density (Br). .
なお、 低 R合金の段階で R 2T14B相内に相内生成物が確認されている比較例 3について、その R— T一 B系希土類永久磁石に相内生成物が存在しない理由は 以下のとおりと推測される。 低 R合金の段階で R2T14B相内に生成された Z r に富む生成物 （相内生成物） は非常に大きく成長している。 この生成物は水素粉 砕処理によっても体積膨張を起こさないと推定され、そのために水素粉砕時に R 2 T i 4 B相と当該生成物の界面で割れが生じているものと解される。 この状態で 粉砕工程に供されると、 当該生成物は R2T14B相と分離される結果、 当該生成 物は R2T14B相内に含まれることなく R2T14B相と独立に存在する。 したが つて、 比較例 3による R— T— B系希土類永久磁石は、 焼結過程を経ても、 その 粒界相にのみ Z rに富む生成物が存在するようになるものと考えられる。 In Comparative Example 3 in which an in-phase product was confirmed in the R 2 T 14 B phase at the stage of the low R alloy, the reason why the in-phase product did not exist in the R--T-B rare earth permanent magnet was as follows. It is assumed that: Low R alloy stage R 2 T 14 B-rich product Z r generated in the intra-phase of (Aiuchi product) is growing very large. It is presumed that this product does not undergo volume expansion even by the hydrogen pulverization treatment. Therefore, it is understood that cracking has occurred at the interface between the R 2 T i 4 B phase and the product during hydrogen pulverization. When subjected to a milling process in this state, the product results to be separated from the R 2 T 14 B phase, the product is a R 2 T 14 B phase without being included in the R 2 T 14 B Aiuchi Exists independently. Therefore, it is considered that the RTB-based rare earth permanent magnet according to Comparative Example 3 contains a Zr-rich product only in the grain boundary phase even after the sintering process.
実施例 1による Z r量力 SO. 10 w t %の1 一 T— B系希土類永久磁石につい て上記と同様にして T EMによる観察を行つた。観察結果を第 6図〜第 8図に示 す。 なお、 第 6図は Z r量が 0. 1 0 w t%の試料の TEM写真、 第 7図は当該 試料に存在する生成物及び当該試料における R2T14B相の ED S (Energy Dispersiveon X- ray Fluorescence Spectroscopymeter：ェ不ル =分散型 X線分 析装置分光法） プロファイル、 第 8図は当該試料の TEM高分解能写真である。 第 6図に示すように、 R2T14B相内に、 軸比の大きな相内生成物が確認でき る。 この生成物は、 板状又は針状の形態を有している。 なお、 第 6図は試料の断 面を観察したものであるから、相内生成物が板状である力、針状であるかを特定す ることは困難である。他の試料の観察結果及び第 8図をも考慮すると、相內生成 物は数 100 nmの長さ、数 nm〜 15 nmの幅を有している。 この相内生成物 の詳細な化学組成は不明確である力 第 7図 （a) より、 この相内生成物は少な くとも Z rに富むことが確認できる。 また、他の試料の観察結果では、 軸比の大 きな相内生成物の他に、 第 9図及ぴ第 10図に示すように、 不定形、 円形の相内 生成物を観察することもできる。 なお、 実施例 1においては 20個の結晶粒 （R 2T14B相）を観察した結果、その内に 6個の結晶粒に相内生成物が観察できた。 それに対して、 比較例 2では 20個の結晶粒 （R2T14B相） 全てについて相内 生成物は観察されなかった。 In the same manner as described above, a TEM observation was conducted on a single T—B-based rare earth permanent magnet having a Zr power of 10 wt% and a Zr power according to Example 1. The observation results are shown in Figs. Fig. 6 is a TEM photograph of a sample with a Zr content of 0.10 wt%, and Fig. 7 is the product present in the sample and the EDS (Energy Dispersiveon X) of the R 2 T 14 B phase in the sample. -ray Fluorescence Spectroscopymeter (profile = dispersive X-ray spectroscopy) Profile, Fig. 8 is a TEM high-resolution photograph of the sample. As shown in FIG. 6, an in-phase product having a large axial ratio can be confirmed in the R 2 T 14 B phase. This product has a plate-like or needle-like form. Since FIG. 6 shows the cross section of the sample, it is difficult to specify whether the in-phase product is plate-shaped or needle-shaped. Considering also the observation results of other samples and FIG. 8, the companion product has a length of several 100 nm and a width of several nm to 15 nm. The detailed chemical composition of this in-phase product is unclear. From Fig. 7 (a), it can be confirmed that this in-phase product is at least rich in Zr. Also, the observation results of other samples show that the axial ratio is large. In addition to the in-phase products, amorphous and circular in-phase products can be observed as shown in FIGS. 9 and 10. In Example 1, as a result of observing 20 crystal grains (R 2 T 14 B phase), an in-phase product was observed in 6 crystal grains. In contrast, in Comparative Example 2, no in-phase product was observed for all 20 crystal grains (R 2 T 14 B phase).
第 11図 （ a ) の下段に、 実施例 1の Z r量が 0. 10wt %の試料の E PM A (Electron Probe Micro Analyzer：電子泉マイクロアナライザ） による Z r マッピング結果を示す。 第 11図 （a) の上段に、 第 1 1図 （a) の下段に示し た Z rマッピング結果と同一視野の組成像を示す。 また、 第 11図 （b) の下段 に、比較例 2の Z r量が 0. 10 w t%の試料の EPMAによる Z rマッピング 結果を示す。 第 11図 （b) の上段に、 第 1 1図 （b) の下段に示した Z rマツ ビング結果と同一視野の組成像を示す。 The lower part of Fig. 11 (a) shows the Zr mapping result of the sample of Example 1 having a Zr content of 0.10 wt% by using an EPMA (Electron Probe Micro Analyzer). The upper part of Fig. 11 ( a ) shows the composition image of the same field of view as the Zr mapping result shown in the lower part of Fig. 11 (a). The lower part of Fig. 11 (b) shows the results of Zr mapping by EPMA of the sample of Comparative Example 2 having a Zr content of 0.10 wt%. The upper part of Fig. 11 (b) shows the composition image in the same field of view as the Zr matting result shown in the lower part of Fig. 11 (b).
TEMによる観察結果と同様に、 第 11図 （a) から、 実施例 1は、 Z rに富 む R2T14B相が存在すること、 及び粒界相にも Z rが存在することがわかる。 これに対して、 第 11図 （b) から、 比較例 2には Z rに富む R2T14B相は確 認されず、 Z rは粒界相のみに存在している。 As in the TEM observation results, FIG. 11 (a) shows that in Example 1, the presence of the Zr-rich R 2 T 14 B phase and the presence of Zr also in the grain boundary phase were observed. Understand. On the other hand, from FIG. 11 (b), the R 2 T 14 B phase rich in Zr was not confirmed in Comparative Example 2, and Zr was present only in the grain boundary phase.
<第 2実施例〉 <Second embodiment>
焼結体組成の添加元素 M (Z r或いは T i ) 量を 0. 10 w t %とした試料に ついて 1◦ 10°C〜1090°Cの温度範囲でそれぞれ 4時間焼結した以外は第 1実施例と同様にして R— T— B系希土類永久磁石を得た。得られた永久磁石に ついて第 1実施例と同様にして磁気特性を測定した。その結果を第 12図に示す。 また、焼結温度に対する磁気特性の変化を第 13図〜第 15図に示す。 また、各 焼結温度における磁気特性を、 残留磁束密度 （B r) に対する角形比 （HkZH c J) としてプロットしたものを第 16図に示す。  For the sample with the additive element M (Zr or Ti) content of 0.10 wt% in the sintered body composition, the first step was performed except that each was sintered for 4 hours at a temperature range of 1 ° C to 1090 ° C. An RTB rare earth permanent magnet was obtained in the same manner as in the example. The magnetic properties of the obtained permanent magnet were measured in the same manner as in the first example. Fig. 12 shows the results. FIGS. 13 to 15 show the change in the magnetic properties with respect to the sintering temperature. Fig. 16 shows the magnetic properties at each sintering temperature plotted as the squareness ratio (HkZHcJ) with respect to the residual magnetic flux density (Br).
第 12図〜第 16図に示すように、 添加元素 Mとして Z rを添加することで 相内生成物が得られた場合に、 広レ、焼結温度範囲で高磁気特性が安定して得ら れることがわかる。 具体的には、 本発明による実施例 2では、 1030〜10 90°Cの焼結温度範囲において、 13. 9 kG以上の残留磁束密度 （B r)、 1 3. 0 k〇 e以上の保磁力 （H c J ) 及ぴ 95 %以上の角形比 （H k ZH c J) を得ることができる。 添加元素 Mとして T iを添加すると残留磁束密度 （B r) が低下し （比較例 4)、 また相内生成物が存在しない場合には角形比 （HkZH c J) が悪く、 焼結温度幅も狭い （比較例 5)。 As shown in Figs. 12 to 16, when an in-phase product was obtained by adding Zr as an additive element M, high magnetic properties were obtained stably over a wide range of sintering temperatures. It can be seen that Specifically, in Example 2 according to the present invention, in a sintering temperature range of 10.30 to 90 ° C, a residual magnetic flux density (Br) of 13.9 kG or more, 1 A coercive force (HcJ) of 3.0 k〇e or more and a squareness ratio (HkZHcJ) of 95% or more can be obtained. When Ti is added as an additive element M, the residual magnetic flux density (Br) decreases (Comparative Example 4), and when there is no in-phase product, the squareness ratio (HkZHcJ) is poor and the sintering temperature range is poor. Is also narrow (Comparative Example 5).
く第 3実施例 > Third embodiment>
ロール周速を 0. 6〜1. 8 m// sとしてストリップキャスト法により、 第 1 7図に示す組成及び厚さを有する 4種の低 R合金、 2種の高 R合金を作製した。 そして第 1 7図に示す組合せによって 4種類の R -T-B系希土類永久磁石を 得た。 なお、試料 A〜Dのいずれについても、 低 R合金と高 R合金の混合比率は 90 : 10である。第 17図に示す低 R合金と高 R合金を第 1実施例と同様に水 素粉砕した。 水素粉碎処理後、 0. 05 w t %のォレイン酸ブチルを添加し、 低 R合金及び高 R合金を第 17図に示す組合せによりナウターミキサーで 30分 混合した。 その後ジェットミルにて平均粒径 4. 1 //mに微粉砕した。 得られた 微粉末を第 1実施例と同様の条件で磁場中成形後、 1010〜1090°Cで 4時 間焼結を行った。 次いで、 800。(で 1時間と 550 °Cで 2. 5時間の 2段時効 処理を行った。 得られた焼結体の組成、 酸素量、 窒素量を第 17図に、 また磁気 特性を第 18図に示す。  Four low-R alloys and two high-R alloys having the compositions and thicknesses shown in FIG. 17 were produced by strip casting with a roll peripheral speed of 0.6 to 1.8 m // s. Then, four kinds of R-T-B rare earth permanent magnets were obtained by the combination shown in Fig.17. The mixture ratio of the low R alloy and the high R alloy was 90:10 for all samples A to D. The low R alloy and the high R alloy shown in FIG. 17 were pulverized with hydrogen in the same manner as in the first embodiment. After the hydrogen crushing treatment, 0.05 wt% of butyl oleate was added, and the low R alloy and the high R alloy were mixed in a Nauter mixer for 30 minutes using the combination shown in FIG. Then, it was pulverized with a jet mill to an average particle size of 4.1 // m. The obtained fine powder was compacted in a magnetic field under the same conditions as in the first example, and then sintered at 1,010 to 1,090 ° C for 4 hours. Then 800. (The two-stage aging treatment was performed for 1 hour and 2.5 hours at 550 ° C. The composition, oxygen content, and nitrogen content of the obtained sintered body are shown in Fig. 17, and the magnetic properties are shown in Fig. 18. Show.
第 18図に示すように、試料 Aにおいては、 1030〜 1070°Cの温度範囲 において 14. O kG以上の残留磁束密度 （B r)、 13. 0 k〇 e以上の保磁 力 (He J) 及ぴ 95%以上の角形比 (Hk/Hc J) を得ることができる。 試料 Aに比べて Nd含有量の低い試料 B及び試料 Cにおいては、 1030〜1 090°Cの温度範囲において 14. 0 kG以上の残留磁束密度 （B r )、 13. 5 kOe以上の保磁力 (He J) 及ぴ 95。/。以上の角形比 （H k ZH c J ) を得 ることができる。  As shown in Fig. 18, in sample A, in the temperature range of 1030 to 1070 ° C, the residual magnetic flux density (Br) of 14. OkG or more and the coercive force (He J ) And a squareness ratio (Hk / Hc J) of 95% or more. For Samples B and C, which have a lower Nd content than Sample A, a residual magnetic flux density (Br) of 14.0 kG or more and a coercive force of 13.5 kOe or more in the temperature range of 1030 to 1090 ° C (He J) and 95. /. The above squareness ratio (H k ZH c J) can be obtained.
試料 Aに比べて D y量の多い試料 Dにおいては、 1030〜 1070°Cの温度 範囲において 13. 5 kG以上の残留磁束密度 （B r)、 15. 5 k O e以上の 保磁力（He J)及ぴ 95%以上の角形比（HkZHc J)を得ることができる。 また、 1050°Cで焼結した試料を TEMによる観察を行った結果、全ての試 料で、 相内生成物が観察された。 ' In sample D, which has a greater amount of Dy than sample A, the residual magnetic flux density (Br) of 13.5 kG or more and the coercive force (He of 15.5 kOe or more) in the temperature range of 1030 to 1070 ° C. J) and a squareness ratio (HkZHc J) of 95% or more can be obtained. As a result of TEM observation of the sample sintered at 1050 ° C, In-phase products were observed with the feed. '
以上の結果より、 相内生成物が存在する場合、 高い磁気特性を 40°C以上の 広い焼結温度幅で安定して得ることができる。  From the above results, when the in-phase product is present, high magnetic properties can be obtained stably over a wide sintering temperature range of 40 ° C or more.
<第 4実施例 >  <Fourth embodiment>
2種の低 R合金、 2種の高 R合金をストリップキャスト法により作製し、第 1 9図に示す組合せによって 2種類の R— T一 B系希土類永久磁石を得た。 なお、 試料 Eについては、 低 R合金と高 R合金の混合比率は 90 ： 10である。 一方、 試料 Fについては、 低 R合金と高 R合金の混合比率は 80： 20である。 第 1 9 図に示す低 R合金と高 R合金を第 1実施例と同様に水素粉砕した。水素粉砕処理 後、 0. 05 w t%のォレイン酸ブチルを添加し、低 R合金及び高 R合金を第 1 9図に示す組合せによりナウターミキサーで 30分混合した。その後ジエツトミ ルにて平均粒径 4. 0 μπιに微粉碎した。 得られた微粉末を第 1実施例と同様の 条件で磁場中成形後、試料 Eについては 1070°Cで 4時間、試料 Fについては 1020°Cで 4時間、 それぞれ焼結を行った。 次いで、 試料 E、 試料 Fのそれぞ れについて 800°Cで 1時間と 550°Cで 2. 5時間の 2段時効処理を行った。 得られた焼結体の組成、 酸素量、 窒素量を第 19図に、 また磁気特性を第 20図 に示す。 なお、 比較の便宜のために、 第 3実施例で作製した試料 A〜Dの磁気特 性も、 第 20図に併せて示す。  Two kinds of low R alloys and two kinds of high R alloys were produced by the strip casting method, and two kinds of RT—B rare earth permanent magnets were obtained by the combination shown in FIG. For sample E, the mixture ratio of low R alloy and high R alloy is 90:10. On the other hand, for sample F, the mixing ratio of the low R alloy and the high R alloy is 80:20. The low R alloy and the high R alloy shown in FIG. 19 were pulverized with hydrogen in the same manner as in the first embodiment. After the hydrogen pulverization treatment, 0.05 wt% of butyl oleate was added, and the low R alloy and the high R alloy were mixed for 30 minutes with a Nauta mixer using the combination shown in FIG. After that, it was pulverized with a jet mill to an average particle size of 4.0 μπι. The obtained fine powder was molded in a magnetic field under the same conditions as in the first example, and then sintered for 10 hours at 1070 ° C for sample E and 4 hours at 1020 ° C for sample F. Next, Sample E and Sample F were subjected to two-stage aging treatment at 800 ° C for 1 hour and at 550 ° C for 2.5 hours. The composition, oxygen content and nitrogen content of the obtained sintered body are shown in FIG. 19, and the magnetic properties are shown in FIG. For comparison, the magnetic properties of Samples A to D produced in Example 3 are also shown in FIG.
試料 A〜Fのように構成元素を変動させても、 1 3. 8 kG以上の残留磁束密 度（B r)、 13. O kOe以上の保磁力 （He J)及び 95%以上の角形比 （H k/Hc J) を得ることができた。 産業上の利用可能性  Even if the constituent elements fluctuate as in Samples A to F, the residual magnetic flux density (Br) of 13.8 kG or more, the coercive force (He J) of 13.O kOe or more, and the squareness of 95% or more (H k / Hc J) could be obtained. Industrial applicability
以上詳述したように、 R— T— B系希土類永久磁石の主相を構成する R2T14 B相内に Z rに富む生成物を存在させることで、磁気特性の低下を最小限に抑え つつ粒成長を抑制することができる。 また本発明によれば、 40°C以上の焼結温 度幅を確保することができるため、加熱温度ムラが生じやすい大型の焼結炉を用 いた場合でも、安定して高い磁気特性を有する R— T— B系希土類永久磁石を容 易に得ることができる c As described in detail above, the presence of Zr-rich products in the R 2 T 14 B phase that constitutes the main phase of the R—T—B rare earth permanent magnet minimizes the deterioration of magnetic properties. It is possible to suppress grain growth while suppressing. Further, according to the present invention, since a sintering temperature range of 40 ° C. or more can be secured, even when a large sintering furnace in which heating temperature unevenness is likely to occur is used, stable and high magnetic properties are obtained. R—T—B rare earth permanent magnet Easily obtainable c

Claims

請 求 の 範 囲 The scope of the claims
1. R2T14B相 （Rは希土類元素の 1種又は 2種以上（但し希土類元素は Yを 含む概念である） 、 Tは F e又は F e及び C oを必須とする 1種又は 2種以上 の遷移金属元素） からなる主相と、 1. R 2 T 14 B phase (R is one or more rare earth elements (where the rare earth element is a concept including Y), T is one or more of Fe or Fe and Co indispensable) A main phase composed of two or more transition metal elements)
前記主相より Rを多く含む粒界相とを含む焼結体からなり、  A sintered body containing a grain boundary phase containing more R than the main phase,
前記 R2T14B相内に Z rに富む生成物が存在することを特徴とする R— T 一 B系希土類永久磁石。 An R—T—B-based rare earth permanent magnet, characterized in that a product rich in Zr is present in the R 2 T 14 B phase.
2. 前記生成物は、 板状又は針状であることを特徴とする請求項 1に記載の R -T-B系希土類永久磁石。 2. The R-T-B-based rare earth permanent magnet according to claim 1, wherein the product is plate-like or needle-like.
3. 前記焼結体中に含まれる酸素量が 2000 p pm以下であることを特徴と する請求項 1に記載の R— T一 B系希土類永久磁石。 3. The RTB rare earth permanent magnet according to claim 1, wherein the amount of oxygen contained in the sintered body is 2000 ppm or less.
4. 前記焼結体は、 R： 28〜 33 w t %、 B ： 0. 5〜 1. 5 w t %、 A 1 ： 0.03〜 0. 3 w t %、 C u ： 0. 3 w t %以下 （ 0を含まず） 、 Z r ： 0. 0 5〜 0. 2 w t %、 C o ： 4 w t %以下 （ 0を含まず） 、 残部実質的に F eから なる組成を有することを特徴とする請求項 1に記載の R _ T— B系希土類永久 磁石。 4. The sintered body is as follows: R: 28 to 33 wt%, B: 0.5 to 1.5 wt%, A1: 0.03 to 0.3 wt%, Cu: 0.3 wt% or less (0 ), Zr: 0.05 to 0.2 wt%, Co: 4 wt% or less (not including 0), and the balance being substantially Fe. Item 4. The R_T—B-based rare earth permanent magnet according to item 1.
5. 前記焼結体において、 Z r ： 0. ；!〜 0. 1 5 w t%であることを特徴とす る請求項 4に記載の R— T _ B系希土類永久磁石。 5. The RTB-based rare earth permanent magnet according to claim 4, wherein in the sintered body, Zr: 0.;! To 0.15 wt%.
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JP4076179B2 (en) 2008-04-16
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CN1572005A (en) 2005-01-26
WO2004030000A1 (en) 2004-04-08

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