WO2000012771A1 - Alliage pour l'elaboration d'un aimant fritte de base r-t-b et procede correspondant - Google Patents
Alliage pour l'elaboration d'un aimant fritte de base r-t-b et procede correspondant Download PDFInfo
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- WO2000012771A1 WO2000012771A1 PCT/JP1998/003840 JP9803840W WO0012771A1 WO 2000012771 A1 WO2000012771 A1 WO 2000012771A1 JP 9803840 W JP9803840 W JP 9803840W WO 0012771 A1 WO0012771 A1 WO 0012771A1
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- 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
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/04—Making non-ferrous alloys by powder metallurgy
- C22C1/0433—Nickel- or cobalt-based alloys
- C22C1/0441—Alloys based on intermetallic compounds of the type rare earth - Co, Ni
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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
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
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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
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
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- 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
Definitions
- the present invention relates to an alloy used for producing a high performance RTB-based sintered magnet and a method for producing the sintered magnet, and more particularly, to a high coercive force RTB-based which is mainly used for motors and the like.
- the present invention relates to a raw material alloy used for manufacturing a sintered magnet and a method for manufacturing the sintered alloy. Background art
- R—T—B sintered magnets as high-performance sintered magnets (where R is at least one of the rare earth elements including Y, T is Fe, and some are Co and Ni) Transition elements that can be replaced by one or two types) are indispensable functional materials that support the downsizing, weight reduction and high performance of magnet application parts.
- RTB sintered magnets are used in a wide range of fields such as electronics products, various motors for OA and FA, and medical diagnostic equipment. Recently, RTB sintered magnets have also been used in various motors for automobiles.
- R—T—B-based sintered magnets are composed of ferromagnetic phases R 2 T 14 B, R rich phases (non-magnetic phases with a high concentration of rare earth elements such as Nd) and B-rich phases ( B is a rich non-magnetic phase, for example, when R is N d, it is N d, and it is a FeB 4 phase).
- R - T one B based sintered material alloy used in the manufacture of magnets also typically, R 2 T, 4 B phase, consisting of R Li pitch-phase and B-Li pitch phase.
- R 2 T, 4 B phase consisting of R Li pitch-phase and B-Li pitch phase.
- the R-rich phase is the key to liquid phase sintering and is an indispensable phase because it plays an important role in improving the properties of sintered magnets. Since this R-rich phase is easily oxidized, it is oxidized in the manufacturing process of the sintered magnet. More than effective after oxidation
- the R content of the sintered alloy is much higher than the R content of R 2 T 14 B, 11.8 at%, so that the R rich phase remains during sintering.
- the higher the properties of the sintered magnet the higher the volume fraction of the R 2 T 14 B phase, which is a ferromagnetic phase, and the lower the volume fraction of the R-rich phase. Therefore, when the raw material alloy is manufactured by the mold manufacturing method, the dispersion of the R-rich phase in the ingot becomes poor, and a local R-rich phase shortage occurs. It is difficult to obtain sufficient magnetic properties with a sintered magnet using a raw material powder obtained by grinding such an ingot.
- an alloy having a composition with a higher volume fraction of the R 2 T 14 B phase is more likely to form a dendritic ⁇ -Fe phase.
- This aFe phase significantly impairs the pulverizability of the raw material alloy, resulting in a change in the composition of the pulverized powder and a decrease in the magnetic properties and an increase in the dispersion of the sintered magnet.
- a considerable amount of the c ⁇ Fe phase can be eliminated by heat-treating the raw material for a long time at 100 ° C. or higher in an inert gas such as Ar gas or in a vacuum.
- this heat treatment does not improve the magnetic properties because the dispersibility of the R-rich phase deteriorates.
- a strip casting method has been proposed as a method for solving these problems relating to the manufacture of high-performance sintered magnets (for example, Japanese Patent Application Laid-Open Nos. 5-22488, 5-208). No. 2,954,900).
- a thin alloy having an average thickness of about 0.1 to 0.5 mm is formed by controlling the peripheral speed of the roll and the amount of molten metal supplied when the molten metal is supplied to the surface of the rotating roll to produce an alloy.
- an alloy having no dendritic a Fe phase can be obtained up to an Nd content of about 28.5% by weight.
- R—T—B alloys with low R content (hereinafter referred to as “main phase alloys”) and R—T or R—T—B alloys with high R content (hereinafter “ ) are prepared separately, and these alloys are mixed to form a sintered magnet.
- main phase alloys R—T or R—T—B alloys with high R content
- a two-alloy mixing method for producing R see, for example, Japanese Patent Application Laid-Open No. 4-33867.
- a chemically stable R is obtained.
- 3 (F e ⁇ C o) can be generated to suppress the oxidation of the grain boundary phase alloy during the production of the sintered magnet (Japanese Patent Laid-Open No. 7-28016).
- the RTB-based alloy fine powder with slightly oxidized surface does not undergo rapid oxidation even when exposed to the atmosphere, so it is possible to form a magnetic field in the atmosphere. Therefore, in the fine pulverization step usually performed in the production of sintered magnets, for example, in a jig mill pulverization step, fine pulverization is performed in an inert gas atmosphere containing a small amount of oxygen gas, and the oxygen concentration becomes 400- A fine powder of 1000 Ppm is produced, and is subjected to magnetic field molding in the atmosphere.
- a high-performance sintered magnet with a small amount of R and a small R-rich phase has a lower allowable oxygen concentration in order to prevent the magnet properties from deteriorating.
- the surface of the fine powder cannot be oxidized as described above in order to effectively use the small R rich phase, and when molding with a magnetic field molding machine, the entire mold is filled with N 2 gas or Ar. It is necessary to take measures such as placing the glove box in a gas atmosphere and forming a magnetic field inside the glove box. In other steps, it is necessary to remove the cause of oxidation as much as possible, which increases costs.
- the size of the crystal grains must be suppressed to about 10 to 30 ⁇ .
- the oxygen concentration in the sintered magnet is kept too low, crystal grains tend to grow abnormally during sintering, and in some cases, grow to about 1 mm. Disclosure of the invention
- the present inventor has proposed a raw material alloy and a method for manufacturing a sintered magnet, which are hardly oxidized in the manufacturing process of the sintered magnet and in which abnormal growth of crystal grains does not easily occur, and which is used for manufacturing a high-performance sintered R-FeB magnet. More specifically, we investigated the raw material alloys used in the manufacture of high coercivity rare earth sintered magnets mainly used for motors and the like, and methods for manufacturing sintered magnets.
- the present invention relates to R 2 T 14 B (where R is at least one kind of rare earth element including Y, and ⁇ is F which can be partially substituted with one or two kinds of C ⁇ and Ni). e, and B is B (boron), a part of which can be replaced with one or two of C and N).
- R is a rare earth element having a total amount of 10 to 11.8 at%, consisting of 1 to 6 & 7% of 0 and the balance of at least one of Nd and Pr, and containing B 5.8 to 8.00 at%
- dendritic a Fe phase may be dispersed in the first region of the matrix, and lamella in the second region separate from the first region.
- the a Fe phase is dispersed, and the total of the first region and the dendritic a Fe phase is 0 to 10% by volume. May be 0% by volume), and the total of the second region and the lamellar a Fe phase is 5% by volume or more.
- an R—T—B-based main phase alloy that cannot be liquid-phase sintered alone because it has a low R content and has substantially no R-rich phase
- a method for producing a sintered magnet by mixing one or two of the R-T or RT-B grain boundary phase alloys, which is responsible for supplying the R-rich phase to the base alloy, (3).
- R 2 T 14 B (where R is at least one of the rare earth elements including Y, and ⁇ is Fe that can be partially substituted with one or two of Co and Ni) And B is boron (boron), a part of which can be substituted with one or two of C and N).
- a dentrite-like a Fe phase is dispersed and generated in the matrix (see details). Is described later.) The area is 10% by volume or less.
- R consists essentially of Nd, Pr, and Dy, and the total content is 10-11.8 at%, of which Dy is l-6 at%.
- the content of B is 5.88 to 8.00 at%, and the balance is T.
- R-T alloy or R-T-B alloy containing R at 15 at% or more Preferably, the Co content is 1 at% or more.
- a sintered magnet is manufactured by combining 60% by weight or more of the main phase alloy and 40% by weight or less of the grain boundary phase alloy.
- the main phase-based alloy of the present invention is characterized by the absence of the easily oxidized lamellar linear R-rich phase present in the commonly used raw material alloy for sintering magnets manufactured by the strip casting method. This means that a lamellar a Fe phase is formed. Therefore, oxidation during production of the sintered magnet can be suppressed.
- the main phases constituting the main phase alloy of the present invention are the R 2 T 14 B phase and the B rich phase, which are matrices, in addition to the lamellar ⁇ Fe phase.
- dendrites a Fe phase and dendrites R 2 T and 7 phases may be formed. When these phases are formed, the composition balance is lost, and an R-rich phase is formed near these phases. Are generated in large numbers.
- FIG. 1 is a reflection electron micrograph by SEM of the main phase alloy produced in Example 1 of the present invention.
- FIG. 2 is a reflection electron micrograph by SEM of the main phase alloy produced in Example 2 of the present invention.
- FIG. 3 is a reflection electron micrograph by SEM of a known main phase alloy. BEST MODE FOR CARRYING OUT THE INVENTION
- Figs. 1 and 2 show SEM of a representative tissue of the present invention. A microscopic photograph is shown.
- the gray phase is the matrix R 2 T 14 B phase
- the thin black thin linear phase is the lamellar ⁇ Fe phase.
- the terms of a number of thin black in Figure 2 is R 2 7 phases produced in Dendorai Bok shape, a number of dark black dots Ru Dendorai preparative form a F e Sodea.
- the many white dots near the dendritic R 2 T, 7 phase and dendritic a Fe phase are the R-rich phases formed due to an imbalance in composition.
- the main phases composing the raw material alloy for the production of R-T-B sintered magnets with a known structure that are generally used are the matrix R 2 T 14 B phase, lamellar R-rich phase and B-rich phase. It is a phase.
- a dendritic a Fe phase may be formed. When this phase is formed, the composition balance is lost, and an R-rich phase is formed near this phase.
- FIG. 3 shows a reflection electron micrograph of this known tissue by SEM.
- the phase that looks gray is the matrix R 2 T 14 B phase
- the phase that looks like a white line is the lamellar R-rich phase.
- Many dark black points are dendritic a Fe phases.
- Many white dots near the dendritic a Fe phase are the R-rich phases generated due to the imbalance in composition.
- the melting point of the R-rich phase is about 660 ° C, and when the cooling rate from the solidification to 660 is low or heat treatment is performed at 660 ° C or more, the lamellar R-rich is cut off in the middle. It becomes round.
- the R-rich phase whose shape has been changed in this way is also regarded as a lamellar shape.
- the structure of the main phase alloy of the present invention is the structure of the raw material alloy for manufacturing RTB sintered magnets, which is a commonly used known structure. It turns out that it is clearly different.
- the R component is equal to or less than the R component of the R 2 T 14 B phase, and a lamellar R-rich phase as seen in a known structure is substantially present due to the lack of the R component. Instead, an extra Fe component is generated as a lamellar phase relative to the R component.
- the amount of formation is determined by the lamellar a Fe phase dispersed and generated in the formation region, that is, the first region of the R 2 T 14 B matrix, and the first region.
- the total of the matrix is 5% by volume or more.
- the dendritic a Fe phase which is detrimental to the productivity and magnetic properties of the sintered magnet, is generated in the formation region (that is, the dendrites dispersed and generated in the first region of the R 2 T 14 B phase matrix).
- the sum of the shape a Fe phase and the first region of the matrix is 10% by volume or less, preferably 5% by volume or less, more preferably 0% by volume. If the area in which the dendritic a Fe phase is generated exceeds 10% by volume, the pulverizability of the raw material alloy will be significantly reduced, causing a change in the composition during pulverization, as well as a decrease in magnetic properties and variations. Cause an increase.
- the area where the lamellar a Fe phase is generated ⁇
- the area where the dendritic a Fe phase is generated can be measured by the same volume% and area%.
- the state of the tissue may differ depending on the observation place, so select any 10 or more places on the cross section, take a photograph with a backscattered electron image of the SEM, and calculate the total area of the observed cross section, The total area of the region where the lamella-like aFe phase is generated or the region where the dendritic aFe phase is generated may be obtained, and the ratio between the two may be obtained.
- the R 2 T 17 phase does not cause a problem such as a decrease in the pulverization efficiency in the manufacturing process of the sintered magnet.
- this phase is magnetically a soft phase, and if present in a sintered magnet, reduces the coercive force and squareness.
- mixed grains of a grain boundary phase alloy having an appropriate composition and the main phase alloy are sintered, there is no problem since the grains disappear during sintering.
- Harmful dendritic aFe phases are formed in most areas of alloys manufactured by ordinary mold making methods.
- a strip casting method is suitable. According to this method, since a thin plate having an average thickness of about 0.1 to 0.5 mm can be manufactured, solidification proceeds at a higher cooling rate than the conventional mold manufacturing method.
- strip casting method there are two types of strip casting method, single roll method and twin roll method.
- the single roll method in which the force device is simple and the control of operating conditions is easy, is preferred.
- a He atmosphere having high thermal conductivity may be provided around the roll.
- the method for producing the main phase alloy of the present invention is not limited to strip casting, and a method of producing the structure of the present invention may be appropriately selected.
- composition for forming the structure of the main phase alloy of the present invention is such that R substantially consists of Nd, Pr, and Dy, and the total content thereof is 10 to 11.8 at%; Among them, Dy is contained in 1 to 6 at%, B content is 5.88 to 8.00 at%, and the balance is composed of T.
- R is more than 11.8 at%, a lamella-like R-rich phase, which is easily oxidized, is generated.
- R is less than 1 Oat%, a large amount of dendritic aFe phase is formed even when the structure is cooled by a method having a high cooling rate after the structure, such as a strip casting method. As a result, the generation region cannot be suppressed to 10% by volume or less. For this reason, the content of R was limited to 10 to 11.8a 7%.
- the sintered magnet according to the present invention is suitable for a motor requiring a high coercive force due to high temperature and exposure to a demagnetizing field.
- B is less than 5.88 at%, a large amount of dendritic a Fe phase will be formed, and the formation region cannot be reduced to 10% by volume or less.
- B is insufficient in the composition regardless of the mixing ratio of the grain boundary phase alloy and the main phase alloy.
- a magnetically soft R 2 Fe 17 phase exists after sintering, and the coercive force and squareness are reduced.
- the higher the B content the more difficult it is to form a dendritic aFe phase.
- R is contained at least 15 at%. If the R of the grain boundary phase alloy is less than 15 at%, a Fe phase is likely to be formed. When mixed with a main phase alloy containing a large amount of B so that the composition of the sintered magnet does not become insufficient, the R component after mixing is reduced. For this reason, the allowable oxygen temperature for securing good magnetic properties becomes too low, so that a sintered magnet with good magnetic properties cannot be actually manufactured. Therefore, R must be contained in the grain boundary phase alloy in an amount of 15 at% or more.
- RT-based alloys and RT-B-based alloys can be used in combination.
- the grain boundary phase alloy of the present invention can be produced by a usual die manufacturing method, a centrifugal manufacturing method (for example, Japanese Patent Application Laid-Open No. 8-296005), or a strip casting method. Whether or not to produce may be appropriately selected depending on the efficiency in pulverization including hydrogen disintegration and the economics involved in production.
- the main phase alloy and the grain boundary phase alloy obtained as described above are mixed and sintered to form a magnet.
- the mixing ratio of the main phase alloy is 60% by weight or more and the grain boundary phase alloy is 40% by weight or less.
- the content of the main phase alloy is less than 60% by weight and the content of the grain boundary phase alloy exceeds 40% by weight, the R contained in the sintered magnet increases and the residual magnetic flux density decreases. Therefore, the main phase alloy must be blended at 60% by weight or more and the grain boundary phase alloy must be blended at 40% by weight or less. Since Co has the effect of improving the corrosion resistance, it is preferable to contain 1 at% or more of Co in the grain boundary phase alloy which has a large R component and is easily oxidized.
- the sintered magnets produced by mixing with the main phase alloy also contain Co to improve the coercive force temperature characteristics and corrosion resistance. However, if the Co content is less than 1 at%, these effects are reduced.
- an inert gas such as N 2 gas or A r gas
- the hydrogen is finely pulverized to 2 to 5 ⁇ by measurement with a Fisher Type Sub-Sibsizer (FSSS).
- FSSS Fisher Type Sub-Sibsizer
- the hydrogen may be crushed in the form of a strip as it is, but it is preferable that the crushing is performed after coarse grinding to 1 Omm or less to expose the metal surface.
- hydrogen pulverization may not be performed, and medium pulverization may be performed immediately after coarse pulverization. Also, if appropriate hydrogen crushing conditions are selected, fine crushing can be performed immediately without performing medium crushing.
- the mixing of the main phase alloy and the grain boundary phase alloy may be performed in any of the pulverization steps of coarse pulverization, hydrogen pulverization, medium pulverization, and fine pulverization. That is, in the present invention, it is important that these alloys are uniformly mixed by the time of the magnetic field forming step, and the present invention is not limited to the selection of the pulverization method and the selection of the mixing method. It is desirable that uniform mixing be performed in an inert gas with a V-type blender. Further, in order to improve the orientation ratio in the magnetic field molding, it is preferable to add a lubricant such as zinc stearate to the mixed powder in an amount of 0.01 to 1% by weight.
- a lubricant such as zinc stearate
- the hydrogen absorbing treatment is preferably performed in a hydrogen atmosphere at a temperature of 100 ° C. or higher.
- the hydrogen gas pressure in the hydrogen atmosphere at this time is preferably from 200 Torr to 10 kgf Z cm 2 from the viewpoint of economy and safety.
- the alloy that generated heat in the hydrogen storage process After partial cooling was evacuated at room temperature for 1 order dehydrogenated, 2 Tsugida' hydroprocessing by further holding ⁇ 7 5 0 e C in 3 0 minutes or more A r or in vacuum 4 0 0 Is preferably performed.
- the oxidation resistance in the next and subsequent steps is improved. From the viewpoint of working efficiency, the primary dehydrogenation treatment can be omitted.
- the uniformly mixed fine powder is formed in a magnetic field molding machine in the air or in an inert gas, and then in a vacuum or in an atmosphere of an inert gas such as Ar gas at 100 to 110 CTC.
- Sinter When hydrogen crushing is performed, it is necessary to safely remove hydrogen from the compact before sintering in order to sufficiently sinter it. Must be kept for more than an hour.
- Aging treatment after sintering improves coercive force.
- Preferred aging treatment conditions are vacuum or an inert gas atmosphere such as Ar gas at 500 to 70 (TC for 1 hour or more, followed by rapid cooling.
- the sintered magnet obtained by the present invention does not grow abnormally even if the oxygen temperature is kept low. Although the reason is not clear, it is considered that the B rich phase present in a large amount in the main phase alloy up to around 140 ° C. suppresses the growth of crystal grains. It is also a feature of the present invention that a large amount of B rich is present in the main phase alloy.
- composition of the present invention will be supplementarily described.
- the T component of the main phase alloy of the present invention requires Fe as an essential component, and a part thereof can be replaced with one or two of Co and Ni to improve the corrosion resistance and temperature characteristics of the sintered magnet. .
- the total substitution amount must not exceed 50% by weight of the T component in the composition after mixed sintering. If it exceeds 50% by weight, a high coercive force cannot be obtained, and the squareness also decreases.
- the B component of the main phase alloy of the present invention can be partially replaced with one or two of C and N.
- the total substitution amount must not exceed 30% by weight of the B + C + N component in the composition after mixed sintering. If it exceeds 30% by weight, a high coercive force cannot be obtained, and the squareness also decreases.
- Cu can be added to the main phase alloy and the grain boundary phase alloy to improve the aging temperature dependence of the coercive force.
- One or more of A 1, Ti, V, Cr, Mn, Nb, Ta, Mo, W, Ca, Sn, Zr, and Hf You may add in combination.
- the total amount of these components including Cu must not exceed 5% by weight in the composition after mixed sintering.
- unavoidable impurities such as ⁇ , La, Ce, Sm, C, 0, N, Si, and Ca in industrial production are allowed. it can.
- the main phase alloy having the composition shown in Table 1 After melting the main phase alloy having the composition shown in Table 1, it was manufactured by strip casting (at a manufacturing temperature of 1450).
- the copper roll used in the strip casting method had a diameter of 40 cm, and the peripheral speed of the copper roll was set at 0.98 m / sec. ⁇ obtained alloy is flaky, the average thickness was 0. 35 mm
- FIG. 1 A backscattered electron photograph of the cross section of the alloy by SEM (scanning electron microscope) is shown in FIG. From the quantitative analysis of each phase by EDX (energy dispersive X-type analyzer) and XRD (powder X-ray diffraction), the matrix phase that appears gray in this photograph is the R 2 Fe 14 B phase, and the black line
- the lamellar phase seen in Figure 2 is the a Fe phase. No lamellar R-rich phase and no dendritic a Fe phase were observed.
- the B-rich phase was confirmed by XRD, but not by reflected electron images. This is probably because the color of the B-rich phase and the color of the R 2 Fe, 4 B phase were very similar in the backscattered electron image, and the two could not be distinguished. You.
- a reflection electrophotographic image of an arbitrary 10 cross sections of the alloy flake was broken by an image processing apparatus to determine a region where a lamellar aFe phase was generated, and it was 95% by volume. The remaining 5% by volume was the portion where only the R 2 Fe 4 B phase was observed.
- a main phase alloy having the composition shown in Table 1 was produced by a strip casting method under the same conditions as in Example 1 to obtain a flake alloy having an average thickness of 0.30 mm.
- a backscattered electron photograph of the cross section of this alloy by SEM is shown in Fig. 2. From the quantitative analysis of each phase by EDX and XRD, the matrix phase that appears gray in this picture is the R 2 Fe 14 B phase, and the phase that appears in the black line is the lamellar a Fe phase, many The black dot phase is a dendritic R 2 Fe 17 phase, and the dark black phase is a dendritic a Fe phase. In addition, dendrites R 2 Fe!
- the white dots around the 7 phase and around the dendritic a Fe phase are R-rich phases.
- the formation area% of the lamellar ⁇ Fe phase and the formation area of the dendritic a Fe phase of this alloy were quantified in the same manner as in Example 1. The results are shown in Table 1.
- a main phase alloy having the composition shown in Table 1 was produced by a strip casting method under the same conditions as in Example 1 to obtain a flake alloy having an average thickness of 0.32 mm.
- the cross-sections of this alloy were identified by SEM backscattered electron image, EDX and XRD, and the main phases confirmed and confirmed were the matrix phase R 2 Fe 14 B phase, lamellar uniform a Fe phase, dendrite R 2 Fe 17 phase, dendritic a Fe phase. Further, around the dendritic R 2 Fe 17 phase and the dendritic a Fe phase, R rich phases were formed in a number of dot-like shapes. In addition, it was confirmed that the B-rich phase was formed only by XRD, and no formation was confirmed by other methods.
- a main phase alloy having the composition shown in Table 1 was produced by the strip casting method under the same conditions as in Example 1.
- the composition of this alloy is a composition in which part of the Fe component of the alloy of Example 1 was replaced with Co.
- the obtained alloy was in the form of flakes, and the average thickness was 0.33 mm.
- the cross-section of this alloy was identified by SEM backscattered electron image, EDX and XRD.
- the main phases formed were the matrix phase R 2 (F e ⁇ Co) 14 B phase and the lamellar a Fe phase.
- the B rich phase was confirmed to be generated only by XRD, but no other method was used to confirm the formation.
- a main phase alloy having a larger amount of R than that of forming the R 2 Fe 14 B phase was formed by a strip casting method under the same conditions as in Example 1 to reduce the average thickness.
- a flake-like alloy of 0.30 mm was obtained.
- the formed phase of this alloy was examined in the same manner as in Examples 1 to 3, a large amount of a lamella-like R-rich phase and a small amount of a dendritic a-Fe phase and a B-rich phase were formed.
- An R-rich phase was formed around the dendritic a Fe phase in the form of many dots. No lamellar a Fe phase was observed.
- the B-rich phase was confirmed to be generated only by XRD, but was not confirmed by other methods.
- a main phase alloy having a composition having no Dy was produced by a strip casting method under the same conditions as in Example 1.
- the average thickness of the obtained flake alloy was 0.29 mm.
- the matrix phases R 2 Fe 14 B phase, lamellar a Fe phase, dendritic a Fe phase, and B It was a phase.
- a large number of R-rich phases were formed around the dendritic aFe phase.
- the B-rich phase was confirmed to be generated by XRD, but was not confirmed by other methods.
- a main phase alloy having no Dy was produced by a strip casting method under the same conditions as in Example 1 to obtain a flake-like alloy having an average thickness of 0.33 mm.
- the matrix phase was an R 2 Fe 14 B phase, a lamellar a Fe phase, and a dendritic a Fe phase.
- R-rich phases were formed around the dendritic a Fe phase in the form of dots.
- the matrix phase was R 2 Fe 14 B phase, lamella-like a Fe phase, dendritic R 2 Fe 17 phase, dendritic a Fe phase. Further, around the dendrite-like R 2 Fe 17 phase and the dendrite-like a Fe phase, an R-rich phase was formed in a number of dot shapes. The B-rich phase was confirmed to have been generated by XRD, but was not confirmed by other methods.
- Example 1 As shown in Table 1, a main phase alloy having a large amount of B was produced by a strip casting method under the same conditions as in Example 1. A flake-like alloy with an average thickness of 0.32 mm was obtained.
- the matrix phase was R 2 Fe 14 B phase, lamella-like a Fe phase, dendritic R 2 Fe 17 phase, dendritic a Fe phase. Further, around the dendritic R 2 Fe 17 phase and the dendritic a Fe phase, many R-rich phases were formed in the form of dots. It was confirmed by XRD that the B-rich phase was produced in a larger amount than in Examples 1 to 3.
- Example 3 10.42 8.24 0.01 2.17 7.90 0 ⁇ .68 0.32 14 9 ⁇ ⁇ ⁇ ⁇ ⁇ ⁇
- the grain boundary phase alloy “R alloy 1” shown in Table 2 was fabricated using a copper mold so as to have a thickness of 5 mm, and pulverized with a jaw crusher to 5 mm or less. The cross section of this alloy was observed by SEM backscattered electron image and EDX, but no a Fe phase was observed.
- the main phase alloy and the R alloy 1 of Example 1 pulverized to 5 mm or less were adjusted to have a weight ratio of 83:17 so that the B-rich phase would be almost eliminated in the composition after the formation of the sintered magnet.
- the obtained mixed powder was pulverized in a N 2 gas by a brown mill to 0.5 mm or less.
- the mixed powder was uniformly mixed with zinc stearate at 0.05 wt%, and then pulverized in a dilute mill in N 2 gas.
- the average particle size of the obtained mixed fine powder was 3.4 ⁇ m (FSSS).
- This mixed fine powder was molded in a magnetic field.
- the green compact was placed in a vacuum furnace, kept at 800 ° C. for 1 hour to completely remove hydrogen from the green compact, and then sintered at 1060 ° C. for 3 hours. After that, aging was performed by holding at 560 ° C for 1 hour in a vacuum, and then quenched. Table 4 shows the magnetic properties of the obtained sintered body.
- the size of the crystal grains was 10 to 15 im, and no abnormally grown crystal grains were observed.
- the grain boundary phase alloy “R alloy 2” shown in Table 2 was produced in the same manner as in Example 5, and was pulverized with a jaw crusher to 5 mm or less. The cross section of this alloy was observed by SEM backscattered electron image and EDX, but no a Fe phase was observed.
- Example 5 a mixed fine powder of the main phase alloy of Example 1 and the R alloy 2 was prepared.
- the total composition of N d, P r, and D y in the composition after making the sintered magnet was almost the same as in Example 5, and the B rich phase was almost eliminated.
- the mixing ratio was 83:17 by weight.
- the average particle size of the obtained mixed fine powder was 3.3 u rn (FSSS).
- Table 4 shows the magnetic properties of the obtained sintered body. Further, observation of the cross section of the sintered body with a polarizing microscope, 1 0 6 0 e grain size of the sintered magnet in C is 1 0 ⁇ 1 5 / xm, 1 1 0 0 ° C The size of the sintered magnet grain at
- Example 5 Using the main phase alloy of Example 4 and the R alloy 2, a mixed fine powder was prepared in the same manner as in Example 5.
- the mixture ratio by weight is 83: 1, so that the total composition of Nd, Pr, and Dy is almost the same as in Example 6 and the B-rich phase is almost eliminated. 7 was set.
- the average particle size of the obtained fine powder was 3.4 ⁇ (FSSS).
- molding in a magnetic field, sintering and aging were performed to produce a sintered magnet. However, the sintering temperatures were set at 106 ° C. and 110 ° C., and the holding time at each was set at 3 hours.
- Table 4 shows the magnetic properties of the obtained sintered body.
- the crystal size of the 106 CTC sintered magnet was 10 to 15 ⁇ , and the crystal size of the 110 C Had a size of 15 to 20 ⁇ . No abnormally grown crystal grains were observed.
- a grain boundary phase alloy “R alloy 3” shown in Table 2 was produced in the same manner as in Example 5, and was pulverized with a jaw crusher to 5 mm or less. The cross section of this alloy was observed by SEM backscattered electron image and EDX, but no a Fe phase was observed.
- a mixed fine powder was prepared in the same manner.
- the mixing ratio was set to 80: 15: 5 by weight so that the B-rich phase was almost eliminated in the composition after conversion to a sintered magnet.
- the average particle size of the obtained fine powder was 3.4 urn (FSSS).
- the sintering temperature is 1 060 e C and 1 1 00 ° C and the retention time for each was 3 hours.
- the size of the crystal grains of the sintered magnet at 106 CTC ranged from 10 to 1501, and the sintered magnet at 1100 ° C.
- the size of the stone grains was 15-20 ⁇ . No abnormally grown crystal grains were observed.
- Example 3 As shown in Table 3, the raw materials were blended so as to have the same composition as the powder mixture of Example 6, and the average thickness was determined by the strip casting method (monoalloy method) under the same conditions as in Example 1. A flake-like alloy having a length of 0.35 mm was obtained.
- This alloy was pulverized in the same manner as in Example 5. However, the hydrogen absorption process in the hydrogen cracking was performed only at room temperature. The average particle size of the obtained fine powder was 3.4 ⁇ m (FSSS). Using this fine powder, in the same manner as in Example 5, molding in a magnetic field, sintering and aging were performed to produce a sintered magnet. However, the sintering temperature is 1 060. C and 110 ° C, and the retention time at each was 3 hours.
- Table 4 shows the magnetic properties of the obtained sintered body.
- the magnetic properties of the 1100 C sintered magnet were lower than those of the 1060 ° C sintered magnet.
- the demagnetization curve of the sintered magnet at 110 ° C was constricted and the squareness was poor.
- the size of the crystal grains was 15 to 20 ⁇ in the sintered magnet at 1060 ° C, and no abnormally grown crystal grains were observed.
- the size of the crystal grains was 15 to 20 ⁇ in the sintered magnet at 1060 ° C, and no abnormally grown crystal grains were observed.
- a large number of coarse crystal grains of about 0.1 to 0.5 mm were also observed by visual observation of the fracture surface.
- a mixed fine powder was prepared in the same manner as in Example 5.
- the mixing ratio was set to 83:17 by weight so that almost no B phase was obtained in the composition after the formation of the sintered magnet.
- the average particle size of the obtained fine powder was 3.3 ⁇ m (FSSS).
- Example 5 Using this mixed fine powder, in the same manner as in Example 5, molding in a magnetic field, sintering, and aging were performed to produce a sintered magnet.
- Table 4 shows the magnetic properties of the obtained sintered body. Compared to the sintered magnet of Example 8, which has a similar composition after magnetization except for the Dy component, this sintered magnet has an extremely large intrinsic coercive force (iHc) because it has too much Dy. On the other hand, the remanent magnetization (B r) force s 1.1 kG and the maximum energy product (BH) max decreased to 9.8 MG 0 e.
- the size of the crystal grains was 10 to 15) txm, and no abnormally grown crystal grains were observed.
- a mixed fine powder was prepared in the same manner as in Example 5.
- the mixing ratio was 83:17 by weight so that the total composition of Nd, Pr, and Dy in the composition after the sintered magnet was almost the same as in Example 6.
- the average particle size of the obtained fine powder was 3.4 ⁇ (F S S S).
- a sintered magnet was produced in the same manner as in Example 5 by molding, sintering and aging in a magnetic field.
- Table 4 shows the magnetic properties of the obtained sintered body. Compared to the sintered magnet of Example 6, which has a similar composition after magnetization except for the ⁇ component, this sintered magnet has too much ⁇ , so the remanent magnetization (B r) is 0.6 kG, The energy product (BH) max decreased to 4.3 MG 0 e.
- a mixed fine powder was prepared in the same manner as in Example 5.
- the mixing ratio was set to 83:17 by weight so that the B-rich phase was almost eliminated in the composition after conversion to a sintered magnet.
- the average particle size of the obtained fine powder was 3.4 urn (FSSS).
- Example 5 Using this mixed fine powder, in the same manner as in Example 5, molding in a magnetic field, sintering and aging were performed to produce a sintered magnet.
- Table 4 shows the magnetic properties of the obtained sintered magnet. The squareness of the demagnetization curve was quite bad. When the Fe component of this sintered magnet was analyzed, it was found to be reduced by 0.4% by weight from the Fe component of the mixed powder after brown milling. On the other hand, when the Fe component of the powder remaining in the jet mill was analyzed, it was found to be 1.5 wt% higher than the Fe component of the mixed powder after the brown milling. From these facts, if a large amount of dendritic aFe phase is formed in the main phase alloy, the aFe phase is difficult to be finely pulverized by the jet mill pulverization, so that it remains in the jet mill. However, it was confirmed that the composition of the powder was shifted to the R-rich side from the original one, and that the magnetic properties of the magnet were also reduced due to the shift in the composition of the powder and a Fe contained in the powder.
- Comparative example 6 1100 7.58 11.7 23.7 29.8 15 ⁇ 20 Comparative example 7 1060 7.52 10.1 30 24.4 15 ⁇ 20
- the grain boundary phase alloy “R alloy 4” shown in Table 2 was produced under the same conditions as in Example 2.
- Electron backscattered electrophotographs were taken at 10 arbitrary positions on the alloy cross section, and the area where the aFe phase was generated by the image processing device was quantified to be 38% by volume.
- Example 5 Using the main phase alloy of Comparative Example 1 and the R alloy 2, a mixed fine powder was produced in the same manner as in Example 5.
- the mixing ratio was 83:17 by weight so that the B-rich phase was almost eliminated in the composition after the conversion to a sintered magnet.
- the average particle size of the obtained fine powder was 3.4 / m (FSSS).
- Example 5 Using the mixed fine powder, magnetic field compaction was performed in the same manner as in Example 5. The change in oxygen concentration of the green compact was measured. Table 5 shows the results. It can be seen that the green compact is easily oxidized as compared with Example 9.
- a dendritic a Fe phase is generated to deteriorate magnetic properties.
- Excellent magnetic properties can be obtained by using the raw material alloys used in the manufacture of B-based sintered magnets.
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Claims
Priority Applications (8)
Application Number | Priority Date | Filing Date | Title |
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PCT/JP1998/003840 WO2000012771A1 (fr) | 1998-08-28 | 1998-08-28 | Alliage pour l'elaboration d'un aimant fritte de base r-t-b et procede correspondant |
AT98940602T ATE241710T1 (de) | 1998-08-28 | 1998-08-28 | Legierung zur verwendung bei der herstellung von gesinterten magneten auf r-t-b-basis und verfahren zur herstellung von gesinterten magneten auf r-t-b-basis |
US09/530,274 US6444048B1 (en) | 1998-08-28 | 1998-08-28 | Alloy for use in preparation of R-T-B-based sintered magnet and process for preparing R-T-B-based sintered magnet |
EP98940602A EP1033415B1 (en) | 1998-08-28 | 1998-08-28 | Alloy for use in preparation of r-t-b-based sintered magnet and process for preparing r-t-b-based sintered magnet |
DE69815146T DE69815146T2 (de) | 1998-08-28 | 1998-08-28 | Legierung zur verwendung bei der herstellung von gesinterten magneten auf r-t-b-basis und verfahren zur herstellung von gesinterten magneten auf r-t-b-basis |
CN98812729A CN1094991C (zh) | 1998-08-28 | 1998-08-28 | 在r-t-b系烧结磁铁的制造中使用的合金 |
JP2000567753A JP4450996B2 (ja) | 1998-08-28 | 1998-08-28 | R−t−b系焼結磁石の製造に用いられる原料合金、合金混合物及びr−t−b系焼結磁石の製造方法 |
FI20000995A FI20000995A (fi) | 1998-08-28 | 2000-04-27 | Seos käytettäväksi R-T-B-pohjaisen magneetin valmistamiseksi |
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PCT/JP1998/003840 WO2000012771A1 (fr) | 1998-08-28 | 1998-08-28 | Alliage pour l'elaboration d'un aimant fritte de base r-t-b et procede correspondant |
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PCT/JP1998/003840 WO2000012771A1 (fr) | 1998-08-28 | 1998-08-28 | Alliage pour l'elaboration d'un aimant fritte de base r-t-b et procede correspondant |
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US (1) | US6444048B1 (ja) |
EP (1) | EP1033415B1 (ja) |
JP (1) | JP4450996B2 (ja) |
CN (1) | CN1094991C (ja) |
AT (1) | ATE241710T1 (ja) |
DE (1) | DE69815146T2 (ja) |
FI (1) | FI20000995A (ja) |
WO (1) | WO2000012771A1 (ja) |
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WO2002018078A2 (en) * | 2000-08-31 | 2002-03-07 | Showa Denko K.K. | Centrifugal casting method, centrifugal casting apparatus, and cast alloy produced by same |
JP2002301554A (ja) * | 2000-08-31 | 2002-10-15 | Showa Denko Kk | 遠心鋳造方法、遠心鋳造装置、それにより製造した合金 |
WO2004029999A1 (ja) * | 2002-09-30 | 2004-04-08 | Tdk Corporation | R−t−b系希土類永久磁石 |
WO2004029995A1 (ja) * | 2002-09-30 | 2004-04-08 | Tdk Corporation | R−t−b系希土類永久磁石 |
WO2004029997A1 (ja) * | 2002-09-30 | 2004-04-08 | Tdk Corporation | R−t−b系希土類永久磁石及び磁石組成物 |
JP2005286175A (ja) * | 2004-03-30 | 2005-10-13 | Tdk Corp | R−t−b系焼結磁石及びその製造方法 |
EP1652606A2 (en) * | 2000-08-31 | 2006-05-03 | Showa Denko K.K. | Centrifugal casting method, centrifugal casting apparatus, and cast alloy produced by same |
US7199690B2 (en) | 2003-03-27 | 2007-04-03 | Tdk Corporation | R-T-B system rare earth permanent magnet |
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CN100405510C (zh) * | 2000-08-31 | 2008-07-23 | 昭和电工株式会社 | 离心铸造方法、离心铸造设备以及利用该方法所生产的铸造合金 |
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- 1998-08-28 EP EP98940602A patent/EP1033415B1/en not_active Expired - Lifetime
- 1998-08-28 CN CN98812729A patent/CN1094991C/zh not_active Expired - Lifetime
- 1998-08-28 WO PCT/JP1998/003840 patent/WO2000012771A1/ja active IP Right Grant
- 1998-08-28 AT AT98940602T patent/ATE241710T1/de not_active IP Right Cessation
- 1998-08-28 US US09/530,274 patent/US6444048B1/en not_active Expired - Lifetime
- 1998-08-28 DE DE69815146T patent/DE69815146T2/de not_active Expired - Fee Related
- 1998-08-28 JP JP2000567753A patent/JP4450996B2/ja not_active Expired - Lifetime
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WO2002018078A3 (en) * | 2000-08-31 | 2003-12-31 | Showa Denko Kk | Centrifugal casting method, centrifugal casting apparatus, and cast alloy produced by same |
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Also Published As
Publication number | Publication date |
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CN1094991C (zh) | 2002-11-27 |
ATE241710T1 (de) | 2003-06-15 |
JP4450996B2 (ja) | 2010-04-14 |
DE69815146D1 (de) | 2003-07-03 |
EP1033415A1 (en) | 2000-09-06 |
EP1033415B1 (en) | 2003-05-28 |
DE69815146T2 (de) | 2004-02-26 |
EP1033415A4 (en) | 2001-04-04 |
US6444048B1 (en) | 2002-09-03 |
CN1283237A (zh) | 2001-02-07 |
FI20000995A (fi) | 2000-04-27 |
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