WO2004029998A1 - R−t−b系希土類永久磁石の製造方法 - Google Patents
R−t−b系希土類永久磁石の製造方法 Download PDFInfo
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- WO2004029998A1 WO2004029998A1 PCT/JP2003/012490 JP0312490W WO2004029998A1 WO 2004029998 A1 WO2004029998 A1 WO 2004029998A1 JP 0312490 W JP0312490 W JP 0312490W WO 2004029998 A1 WO2004029998 A1 WO 2004029998A1
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- 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
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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
- H01F1/0555—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
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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
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 a method for producing an R—T—B-based rare earth permanent magnet mainly containing the above transition metal elements) and B (boron).
- R-TB Rare-Earth Permanent Magnets are increasing in demand year by year because of their excellent magnetic properties, Nd as the main component is abundant in resources and relatively inexpensive. .
- JP-A-1-219143 the magnetic properties are improved and the heat treatment conditions are improved by adding 0.02-0.5 at% of Cu to the R-T-B rare earth permanent magnet. It has been reported.
- the method described in JP-A-11-219143 obtains high magnetic properties required for high-performance magnets, specifically, high coercive force (He J) and residual magnetic flux density (Br). Was not enough.
- the magnetic properties of R_T—B-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 referred to as the sintering temperature range.
- Japanese Patent Application Laid-Open No. 2002-75717 discloses that in a R_T—B-based rare earth permanent magnet containing Co, Al, Cu, and further Zr, Nb or Hf, a fine ZrB compound, Nb It has been reported that by uniformly dispersing and precipitating a B compound or an HfB compound (hereinafter, MB compound), the grain growth during the sintering process is suppressed, and the magnetic characteristics and the sintering temperature range are improved. I have.
- 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, it is desirable to further increase the sintering temperature range in order to obtain high magnetic properties in mass production furnaces.
- 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 intended high characteristics cannot be obtained.
- an object of the present invention is to provide a method for producing an R—T_B-based rare earth permanent magnet that can suppress grain growth while minimizing deterioration of magnetic properties and further improve the sintering temperature range.
- R is one or more rare earth elements (where the rare earth element is a concept including Y), and T is Fe or Mainly Fe and Co
- the alloy for forming the main phase is sometimes called a low R alloy because the content of the rare earth element R is relatively small.
- alloys for grain boundary phase formation are sometimes referred to as high R alloys due to their relatively high content of rare earth element R.
- the inventor of the present invention has stated that when Zr is contained in a low-R alloy when obtaining an RTB-based rare earth permanent magnet by using the mixing method, Z is included in the obtained RTB-based rare earth permanent magnet. It was confirmed that r had high dispersibility. Due to the high dispersibility of Zr, abnormal grain growth can be prevented with a lower Zr content, and the sintering temperature range can be increased.
- R 25 to 35 wt%
- R is one or two or more rare earth elements (where the rare earth element is a concept including Y)
- B 0.5 to 4.5 wt%, one or two of A1 and Cu: 2 to 0.02 to 0.6 wt%, Zr: 0.03 to 0.'25 wt%, C o: 4 wt% or less (excluding 0)
- the balance being a method for producing a R—T-B based rare earth permanent magnet consisting of a sintered body having a composition substantially composed of Fe, wherein R 2 T 14 B A R_T—B-based rare earth element characterized in that a compact containing a low-R alloy containing Zr and a high-R alloy containing R and T as a main component is produced, and this compact is sintered.
- This is a method for manufacturing a permanent magnet.
- the low R alloy further contain one or two of Cu and A 1 in addition to Zr. This is because the inclusion of one or two of Cu and A1 is effective for improving the dispersibility of Zr in the low R alloy.
- the sintering temperature range is improved.
- the effect of improving the sintering temperature range is provided by the magnet composition which is in the state of the powder (or its compact) before sintering. Therefore, in the molded article according to the present invention, the sintering temperature range at which the squareness ratio (HkZHc J) of the RT—B-based rare earth permanent magnet obtained by sintering becomes 90% or more is 40 ° C. or more.
- Zr is 0.05 to 0.2w. t% is desirable, and more preferably 0.1 to 0.15 wt%.
- the composition excluding Zr is as follows: R: 28 to 33 wt%, B: 0.5 to 1.5 wt%, A 1: 0.3 wt% or less (not including 0), Cu: 0.3 wt% or less (not including 0), Co: 0.1 to 2.0 w't% or less, with the balance substantially consisting of Fe
- composition 9 ⁇ 32wt%, B: 0.8 ⁇ l.2wt%, A1: 0.25wt% or less (excluding 0), Cu: 0.15wt% or less (excluding 0), balance It is desirable that the composition be substantially composed of Fe.
- the effect of improving the dispersibility of Zr and expanding the sintering temperature range by including Zr in a low-R alloy is because the amount of oxygen contained in the sintered body is as low as 2000 ppm or less. It becomes noticeable in the case.
- FIG. 1 is a chart showing the chemical compositions of the low R alloy and the high R alloy used in the first embodiment
- FIG. 2 is the final composition of the permanent magnets (No .;! -20) obtained in the first embodiment.
- FIG. 3 is a chart showing the oxygen content and magnetic properties
- FIG. 3 is a chart showing the final composition, oxygen content and magnetic properties of the permanent magnets (No. 21 to 35) obtained in the first embodiment
- FIG. 1 is a chart showing the chemical compositions of the low R alloy and the high R alloy used in the first embodiment
- FIG. 2 is the final composition of the permanent magnets (No .;! -20) obtained in the first embodiment
- FIG. 3 is a chart showing the oxygen content and magnetic properties
- FIG. 3 is a chart showing the final composition, oxygen content and magnetic properties of the permanent magnets (No. 21 to 35) obtained in the first embodiment
- FIG. 6 is a graph showing the relationship between the Zr addition amount and FIG. 6 is a photograph showing an EPMA (Electron Prove Micro Analyzer) element mapping result of the permanent magnet (permanent magnet obtained by adding a high R alloy) obtained in Example 1; Fig.
- FIG. 7 is a photograph showing the results of EPMA element mapping of the permanent magnet obtained in the first embodiment (permanent magnet made of low-R alloy-added kneader), and Fig. 8 is the ZZ of the permanent magnet obtained in the first embodiment.
- Fig. 9 is a graph showing the relationship between the addition method of r, the addition amount of Zr and the CV value (coefficient of variation) of Zr, and Fig. 9 shows the permanent magnets (Nos. 36 to 75) obtained in the second embodiment. Showing final composition, oxygen content and magnetic properties
- FIG. 10 is a graph showing the relationship between the residual magnetic flux density (Br), coercive force (HeJ) and squareness ratio (HkZHcJ) and the Zr addition amount in the second embodiment, and FIG. No.
- FIG. 13 is a graph showing the 4 ⁇ I_ ⁇ curves of the permanent magnets No. 37, No. 39, No. 43, and No. 48 obtained in the second embodiment.
- Fig. 15 shows an example of a profile of a line analysis of a permanent magnet according to Fig. 70 obtained in the second embodiment
- Fig. 15 shows a profile of the permanent magnet according to Fig.
- FIG. 16 is a graph showing the relationship between the amount of added Zr, the sintering temperature, and the squareness ratio (HkZHc J) in the second embodiment.
- FIG. 17 is a graph showing the relationship between the permanent magnet (No. Fig. 18 shows the final composition, oxygen content and magnetic properties of the permanent magnet (Nos. 80 to 81) obtained in the fourth example.
- the RTB-based rare earth permanent magnet according to the present invention is characterized in that Zr is uniformly dispersed in the structure of the sintered body. This feature is more specifically specified by a coefficient of variation (referred to as a CV (Coefficient of Variation) value in the present specification).
- a CV Coefficient of Variation
- the CV value of Zr is 130 or less, preferably 100 or less, and more preferably 90 or less. The smaller the CV value, the higher the degree of dispersion of Zr.
- the CV value is the standard deviation divided by the arithmetic mean (percentage Rate). Further, the CV value in the present invention is a value obtained under the measurement conditions of the examples described later.
- the high dispersibility of Zr is caused by the method of adding Zr.
- the RTB-based rare earth permanent magnet of the present invention can be manufactured by a mixing method.
- the blending method mixes a low R alloy for forming the main phase and a high R alloy for forming the grain boundary phase, but when Zr is contained in the low R alloy, it is contained in the high R alloy. Its dispersibility is significantly improved as compared to.
- Cu is rich in the 1Zr rich region, and both Cu and Co are rich in the 2Zr rich region. 3 It was confirmed that Cu, Co and Nd were all rich in the Zr-rich region. In particular, both Zr and Cu have a high proportion of richness, and Zr is present together with Cu to exert its effect. Also, N d, 0 and 11 are elements forming a grain boundary phase together. Therefore, since Zr in the region is rich, it is determined that Zr exists in the grain boundary phase.
- a liquid phase in which one or more of Cu, Nd and Co and Zr are both rich (hereinafter referred to as “Zr rich liquid phase”) is generated in the sintering process. Is done.
- the Zr rich liquid phase has a different wettability to the RsTwBi crystal grains (compound) than the liquid phase in a normal system not containing Zr. This slows down the rate of grain growth during the sintering process. For this reason, it is possible to suppress grain growth and prevent the occurrence of giant abnormal grain growth.
- the sintering temperature range can be improved due to the Zr rich liquid phase, it is possible to easily manufacture R-T-B rare earth permanent magnets with high magnetic properties. It became so.
- the chemical composition here refers to the chemical composition after sintering.
- the R—T—B system rare earth permanent magnet according to the present invention can be manufactured by a mixing method as described later. However, for each of the low R alloy and the high R alloy used in the mixing method, the manufacturing method is described. Will be mentioned in the description.
- 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. That is it. If the amount of R is less than 25 wt%, the formation of the R 2 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, if the amount of R exceeds 35 wt%, the volume ratio of the main phase R 2 T 14 B 1 decreases, and the residual magnetic flux density decreases. When R exceeds 35 wt%, R reacts with oxygen, increasing the amount of oxygen contained.
- 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 as R is Nd.
- the inclusion of Dy is effective in increasing the anisotropic magnetic field and thus in improving the coercive force. Therefore, it is desirable to select Nd and Dy as R and make the total of Nd and Dy 25 to 33 wt%. And, in this range, the amount of 0 is desirably 0.1 to 8 wt%.
- Dy is determined within the above range depending on which of residual magnetic flux density and coercive force is important. It is desirable. In other words, to obtain a high residual magnetic flux density, the Dy amount should be 0.1 to 3.5 wt%, and to obtain a high coercive force, the Dy amount should be 3.5 to 8 wt%. Is desirable.
- the rare earth permanent magnet of the present invention contains 0.5 to 4.5 wt% of boron (B). 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 4.5 wt%. Desirable B content is 0.5 to 1.5 wt%, and more desirable B content is 0.8 to: 1.2 wt%.
- the RTB-based rare earth permanent magnet of the present invention can contain one or two of A1 and Cu in the range of 0.02 to 0.6 wt%. By including one or two of A1 and Cu in this range, it is possible to increase the coercive force, increase the corrosion resistance, and improve the temperature characteristics of the obtained permanent magnet.
- 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%.
- the amount of ⁇ 11 is 0.3wt% or less (excluding 0), preferably 0.15wt% or less (excluding 0), more preferably Cu Is between 0.03 and 0.08 wt%.
- the RTB-based rare earth permanent magnet of the present invention has a Zr content of 0.03 to 0.25 wt%.
- Zr exerts the effect of suppressing the abnormal growth of crystal grains during the sintering process. To make the structure uniform and fine. Therefore, the effect of Zr becomes remarkable when the oxygen amount 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 RTB rare earth permanent magnet of the present invention has an oxygen content of 2000 ppm or less. If the amount of oxygen is large, the oxide phase, which is a non-magnetic 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 l OOO ppm or less. However, simply reducing the oxygen content reduces the oxide phase, which had the effect of suppressing grain growth, and facilitates grain growth in the process of obtaining a sufficient density increase during sintering. This. 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 ⁇ . %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 present invention provides an R—T—B based rare earth permanent magnet using an alloy mainly composed of R 2 T 14 B phase (low R alloy) and an alloy containing more R than the low R alloy (high R alloy).
- a low-R alloy and a high-R alloy are obtained by strip casting a raw metal in a vacuum or inert gas, preferably in an Ar atmosphere.
- the raw material rare earth metals or rare earth alloys, pure iron, ferroboron, and alloys thereof can be used. If there is solidification segregation, the obtained master alloy is subjected to a solution treatment if necessary.
- the condition may be that the temperature is maintained at 700 to 1500 ° C in a vacuum or Ar atmosphere for 1 hour or more.
- a feature of the present invention is that Zr is added from a low R alloy. This is because the dispersibility of Zr in the sintered body can be improved by adding Zr from a low-R alloy, as described in the section of Structure.
- Low R alloys can contain Cu, Z or A1 in addition to R, T and B. At this time, the low-R alloy constitutes an R-Cu-Al-Zr-T (Fe) -B alloy.
- the high-R alloy may contain one, two or more of Cu, Co, and A1 in addition to R, T (Fe), and B. At this time, the high R alloy forms an R-Cu-Co-A1-T (Fe-Co) -B alloy.
- each of these master alloys is milled separately or together. The grinding process includes a coarse grinding process and a fine grinding process. First, each mother alloy is coarsely pulverized to a particle size of about several hundred ⁇ .
- the process proceeds to the fine grinding step.
- 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 ⁇ .
- the jet mill releases a high-pressure inert gas (for example, nitrogen gas) from a narrow nozzle to generate a high-speed gas flow, accelerates the coarsely pulverized powder with the high-speed gas flow, and causes collision between the coarsely pulverized powders and a target.
- a high-pressure inert gas for example, nitrogen gas
- it is a method of crushing by generating collision with the container wall.
- the finely ground 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 may be performed in a magnetic field of 12.0 to 1.7 O k O e at a pressure of about 0.7 to 1.5 tZ cm 2 .
- the compact After compacting in a magnetic field, the compact is sintered in a vacuum or inert gas atmosphere.
- the sintering temperature must be adjusted according to various conditions such as the composition, grinding method, difference in particle size and particle size distribution, etc., but if sintering is performed at 100 ° C to 110 ° C for about 1 to 5 hours, #2.
- the obtained sintered body can be subjected to an aging treatment.
- Aging is important in controlling coercivity. If the aging process is performed in two stages, it should be around 800 ° C, 600 ° C. It is effective to hold a predetermined time near C. If the heat treatment at around 800 ° C is performed after sintering, the coercive force will increase. It is effective. In addition, since the coercive force is greatly increased by the heat treatment at around 600 ° C., when performing the aging treatment in one stage, it is preferable to perform the aging treatment at around 600 ° C.
- the RT-B rare earth permanent magnet according to the present invention will be described below in the first to fourth embodiments separately. However, since the prepared raw material alloy and each manufacturing process are common, This point will be described.
- each process from hydrogen treatment (recovery after pulverization) to sintering (input to the sintering furnace) Is controlled to an oxygen concentration of less than 100 ppm.
- anoxic process it is referred to as anoxic process.
- the type of the additive is not particularly limited, and those that contribute to the improvement of the pulverizability and the orientation at the time of molding may be appropriately selected.
- zinc stearate is used in an amount of 0.05 to 0. 1% mixed.
- the mixing of the additives may be carried out by, for example, a Nauta mixer for about 5 to 30 minutes.
- both the additive mixing process and the pulverization process are performed using an oxygen-free process.
- the oxygen amount of the fine powder for molding is adjusted in this step.
- a fine powder having the same composition and average particle size is prepared and left in an oxygen-containing atmosphere of 100 ppm or more for several minutes to several hours to obtain a fine powder of several thousand ppm.
- the amount of oxygen is adjusted by mixing these two types of fine powder in an oxygen-free process.
- each permanent magnet was manufactured by the above method.
- the molded body was sintered in a vacuum at 1010 to 110 ° C for 4 hours and then rapidly cooled. Next, the obtained sintered body was subjected to two-stage aging treatment at 800 ° C for 1 hour and at 550 ° C for 2.5 hours (both in an Ar atmosphere).
- the residual magnetic flux density (Br), coercive force (HcJ), and squareness ratio (Hk / HcJ) of the obtained RTB-based rare earth permanent magnet were measured with a BH tracer.
- 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.
- Fig. 4 is a graph showing the relationship between the amount of Zr and the magnetic properties when the sintering temperature is 1070 ° C
- Fig. 5 is the amount of Zr when the sintering temperature is 1050 ° C.
- 3 shows a graph showing the relationship between the magnetic properties and the magnetic properties.
- FIGS. 2 and 3 The results of measuring the amount of oxygen in the sintered body are also shown in FIGS. 2 and 3.
- No.:! -14 have an oxygen content in the range of 1000-1500 ppm.
- Fig. 2 it is in the range of ⁇ .15 to 2 ( ⁇ 1500 to 2000 ⁇ pm.
- Fig. 3 all of Nos. 21 to 35 are in the range of 1000 to 1500 ppm. In the box.
- No. 1 is a material containing no Zr.
- Nos. 2 to 9 are materials with Zr added from low R alloys, and No. 1 ° to 14 are materials with Zr added from high R alloys.
- the material added with Zr from the low R alloy is indicated as low R alloy-added knea, and the material added with Zr from high R alloy is added with high R alloy. are doing.
- FIG. 4 shows a low oxygen content of 1000 to 1500 ppm in FIG.
- a permanent magnet with the addition of low R alloy can achieve a squareness ratio (HkZHc J) of 95% or more with the addition of 0.03% Zr. According to the observation of the yarn, no abnormal grain growth was confirmed. Also, even with the addition of 0.03% or more of Zr, a decrease in the residual magnetic flux density (Br) and coercive force (HeJ) is not observed. Therefore, according to the permanent magnet with the addition of the low R alloy, it is possible to obtain high characteristics by sintering in a higher temperature range, miniaturization of the milled particle size, and production under conditions such as a low oxygen atmosphere.
- FIGS. 2 and 3 Focusing on the relationship between the oxygen content and the magnetic properties, it can be seen from FIGS. 2 and 3 that a high magnetic property can be obtained by setting the oxygen content to 2000 ppm or less. Then, comparing the No. 6 to 8 and No. 16 to No. 18 in Fig. 2, and comparing the No. 11 to 12 and No. 19 to 20, when the oxygen amount is set to 1500 ppm or less, It can be seen that the coercive force (Hc J) increases, which is preferable.
- Hc J coercive force
- No. 21 with no added Zr has a low squareness ratio (HkZHc J) of 86% even when the sintering temperature is 1050 ° C.
- This permanent magnet was also found to have abnormal grain growth in its structure.
- the squareness ratio (Hk / Hc J) improves with the addition of Zr, but the residual magnetic flux density (Br) increases as the Zr addition increases. Is greatly reduced.
- Nos. 31 to 35 in FIG. 3 vary the A1 amount. From the magnetic properties of these permanent magnets, it can be seen that the coercive force (Hc J) is improved by increasing the amount of A1.
- the dispersibility of Zr in the analysis screen was evaluated by CV value (coefficient of variation) from the results of element mapping by EPMA.
- the CV value is the value obtained by dividing the standard deviation of all analysis points by the average value of all analysis points (percentage). A smaller value indicates better dispersibility.
- JCMA733 manufactured by JEOL Ltd. PET (Central Erytol) was used for the spectral crystal) was used, and the measurement conditions were as follows. The results are shown in FIGS. 2 and 8. From Fig. 2 and Fig. 8, the permanent magnet with Zr added from the low R alloy (No. 2-7) is compared with the permanent magnet with Zr added from the high R alloy (No. 10-14). It can be seen that the dispersibility of Zr is excellent.
- Measurement point X ⁇ 200 points (0.15 m steps)
- FIG. 10 is a graph showing the relationship between the sintering temperature and each magnetic property.
- the oxygen content of the sintered body was reduced to 600 to 900 ppm by an oxygen-free process, and the average particle size of the powder frame powder was as small as 4.0 ⁇ m. And Therefore, abnormal grain growth tends to occur during the sintering process. For this reason, permanent magnets that do not add Zr (No. 36 to 39 in Fig. 9 and Zr-free in Fig. 10) have extremely poor magnetic properties except when sintered at 1030 ° C. It has a low value. However, even at 1030 ° C, the squareness ratio (Hk / Hc J) did not reach 88% or 90%.
- the squareness ratio (Hk / Hc J) tends to decrease due to abnormal grain growth as soon as possible.
- the squareness ratio (Hk / Hc J) is an index that can grasp the tendency of abnormal grain growth. Therefore, if the sintering temperature range in which a squareness ratio (Hk / Hc J) of 90% or more is obtained is defined as the sintering temperature range, the sintering temperature range is 0 for permanent magnets to which Zr is not added.
- FIG. 11 shows a micrograph of the fracture surface of each permanent magnet with SEM (scanning electron microscopy) observed for each of the permanent magnets with Nr and Nr 0.05% added and N 0.48 (sintered at 1060 ° C and Zr 0.08% added).
- FIG. 12 shows a 4 ⁇ I curve of each permanent magnet obtained in the second embodiment.
- the CV values were measured for the permanent magnets No. 51 to 66 in FIG. The results are shown in Fig. 9, where the CV value is below 100 in the sintering temperature range (1030 ⁇ : 1090 ° C) where the squareness ratio (HkZHc J) is 90% or more, and the dispersion of Zr The fit is good. However, when the sintering temperature is increased to 115 ° C., the CV value exceeds 130 specified in the present invention.
- FIG. 13 shows a mapping image (30 ⁇ 30 / ⁇ ) of each element of B, Al, Cu, Zr, Co, Nd, 6 and].
- Line analysis was performed on each of the above elements in the area of the mapping image shown in FIG.
- Line analysis was performed on two different lines. One line analysis profile is shown in Fig. 14 and the other line analysis profile is shown in Fig. 15.
- FIG. 16 is a graph showing the relationship among the amount of added Zr, the sintering temperature, and the squareness ratio (HkZHeJ) in the second embodiment.
- the third example was performed as one of the purposes of confirming the change in the magnetic characteristics due to the Dy amount. From Fig. 17, it can be seen that the coercive force (Hc J) increases as the Dy amount increases. On the other hand, each permanent magnet has a Br + 0.1 X He J value of 15.4 or more. This indicates that the permanent magnet according to the present invention can obtain a high level of residual magnetic flux density (Br) while securing a predetermined coercive force (HcJ).
- the permanent magnet of No. 80 in Fig. 18 is composed of alloy a7 and alloy b4 in a weight ratio of 90:10, and the permanent magnet of No. 81 is composed of alloy a8 and alloy b5. : Blended in a weight ratio of 20.
- the average particle size of the powder after the fine powder is 4.0 ⁇ .
- the oxygen content of the obtained permanent magnet is less than l OOO ppm as shown in Fig. 18.When the structure of the sintered body was observed, no coarse crystal grains of 100 ⁇ or more were found. Was.
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Abstract
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Claims
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JP2004539582A JP4076177B2 (ja) | 2002-09-30 | 2003-09-30 | R−t−b系希土類永久磁石の製造方法 |
EP03798558A EP1465213B1 (en) | 2002-09-30 | 2003-09-30 | Method for producing r-t-b based rare earth element permanent magnet |
DE60319339T DE60319339T2 (de) | 2002-09-30 | 2003-09-30 | Verfahren zur herstellung eines seltenerdelement-permanentmagneten auf r-t-b-basis |
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PCT/JP2003/012490 WO2004029998A1 (ja) | 2002-09-30 | 2003-09-30 | R−t−b系希土類永久磁石の製造方法 |
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US (2) | US7255751B2 (ja) |
EP (2) | EP1465213B1 (ja) |
JP (2) | JP4076176B2 (ja) |
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JP2006310797A (ja) * | 2005-03-30 | 2006-11-09 | Tdk Corp | 希土類永久磁石の製造方法 |
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JP2012028704A (ja) * | 2010-07-27 | 2012-02-09 | Tdk Corp | 希土類焼結磁石 |
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Cited By (9)
Publication number | Priority date | Publication date | Assignee | Title |
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EP1462531A2 (en) * | 2003-03-27 | 2004-09-29 | TDK Corporation | R-T-B system rare earth permanent magnet |
EP1462531A3 (en) * | 2003-03-27 | 2005-03-30 | TDK Corporation | R-T-B system rare earth permanent magnet |
US7199690B2 (en) | 2003-03-27 | 2007-04-03 | Tdk Corporation | R-T-B system rare earth permanent magnet |
JP2006310786A (ja) * | 2005-03-28 | 2006-11-09 | Tdk Corp | 希土類永久磁石の製造方法及び原料粉末と潤滑剤の混合方法 |
JP4716020B2 (ja) * | 2005-03-28 | 2011-07-06 | Tdk株式会社 | 希土類永久磁石の製造方法及び原料粉末と潤滑剤の混合方法 |
JP2006310797A (ja) * | 2005-03-30 | 2006-11-09 | Tdk Corp | 希土類永久磁石の製造方法 |
JP4716022B2 (ja) * | 2005-03-30 | 2011-07-06 | Tdk株式会社 | 希土類永久磁石の製造方法 |
JP2012028704A (ja) * | 2010-07-27 | 2012-02-09 | Tdk Corp | 希土類焼結磁石 |
JP2016086078A (ja) * | 2014-10-27 | 2016-05-19 | 日立金属株式会社 | R−t−b系焼結磁石の製造方法 |
Also Published As
Publication number | Publication date |
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US7255751B2 (en) | 2007-08-14 |
EP1465213B1 (en) | 2008-02-27 |
CN1557006A (zh) | 2004-12-22 |
EP1465213A4 (en) | 2005-03-23 |
DE60319800T2 (de) | 2009-03-05 |
US20040118484A1 (en) | 2004-06-24 |
CN1557004A (zh) | 2004-12-22 |
JP4076176B2 (ja) | 2008-04-16 |
CN100334658C (zh) | 2007-08-29 |
EP1465213A1 (en) | 2004-10-06 |
JPWO2004029997A1 (ja) | 2006-01-26 |
US20040166013A1 (en) | 2004-08-26 |
DE60319339T2 (de) | 2009-02-19 |
DE60319800D1 (de) | 2008-04-30 |
EP1460653A4 (en) | 2005-04-20 |
CN100334660C (zh) | 2007-08-29 |
JP4076177B2 (ja) | 2008-04-16 |
EP1460653A1 (en) | 2004-09-22 |
WO2004029997A1 (ja) | 2004-04-08 |
JPWO2004029998A1 (ja) | 2006-01-26 |
EP1460653B1 (en) | 2008-03-19 |
US7192493B2 (en) | 2007-03-20 |
DE60319339D1 (de) | 2008-04-10 |
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