JP2001217112A - R-t-b sintered magnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an R-T-B sintered magnet in which Br(iHc) is improved, while maintaining high iHc(Br) to be the same as or higher than conventional sintered magnets. SOLUTION: In the R-T-B sintered magnet, using an R2T14B type intermetallic compound (R represents one kind or two kinds or more of rare earth elements, containing Y and surely comprising one kind or two kinds or more among Dy, Tb and Ho and T represents Fe or Fe and Co) as the main phase, an anisotropic magnetic field is unevenly distribute, and the distribution width of the anisotropic magnetic field is 159.2 kA/m (2 k0e) or large.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an improved RTB
The present invention relates to a system-based sintered magnet (R is one or two or more rare earth elements including Y and necessarily includes one or two or more of Dy, Tb, and Ho, and T is Fe or Fe and Co).

[0002]

2. Description of the Related Art The production of rare earth magnets is increasing year by year. Also, the need for smaller (thinner) and higher performance magnet-applied products has become increasingly vigorous, and the required maximum energy
The product (BH) max is also increasing every year. Particularly in the information age, magnetic recording is a fundamental technology indispensable, and the improvement of the recording density of HDDs (Hard Disk Drives), which are important components of the technology, is unknown. As an HDD,
A VCM (Voice Coil Motor) using a rare earth magnet is often used as a head driving actuator. recent years,
With the increase in the density of HDDs, there has been a demand for high-performance rare-earth sintered magnets capable of realizing VCMs that are smaller and capable of high-speed, high-precision positioning.

[0003] The improvement in the performance of the RTB-based sintered magnet is achieved by improving the volume ratio of the main phase (R ₂ T ₁₄ B type intermetallic compound phase),
It has been promoted by reducing oxides as inclusions and improving the degree of orientation. However, the anisotropic magnetic field (HA) of the main phase
It was about 5969 kA / m (75 kOe), and it was difficult to improve the coercive force (iHc) when the anisotropic magnetic field was small. The coercive force is substantially determined by the anisotropic magnetic field and the crystal grain size distribution. R-
The anisotropic magnetic field of the TB sintered magnet is such that a part of Nd is converted to Dy or Td.
It can be increased by substitution with a heavy rare earth element such as b.
In this case, it is possible to obtain a series of magnet materials having different coercive forces, although the residual magnetic flux density (Br) slightly decreases. Conventionally, the improvement in the volume fraction of the main phase has been achieved by reducing the volume fraction of the R-rich phase or the B-rich phase, that is, mainly by the total rare earth amount (Total
Rare Earth) as far as possible by selecting an RTB-based alloy composition. However, if the total rare earth amount as short as necessary to maintain the coercive force is selected, the effective total rare earth amount decreases from the critical total rare earth amount at which sintering sufficiently proceeds due to oxidation during sintering, and sintering is performed. This causes a problem that defective products are generated. Next, in order to reduce R oxides (Nd ₂ O ₃ , NdFeO _3, etc.) as inclusions, particularly in a manufacturing process from pulverization to sintering, a raw material for an RTB-based sintered magnet is used. In order to suppress the oxidation of the powder and the compact, a method of maintaining the powder and the compact in an inert gas atmosphere or a method of immersing the fine powder and the compact in a special oil having an oxidation resistance imparting action such as mineral oil (Patent No. No. 2731337, Patent No. 2
No. 859517). Next, the improvement of the degree of orientation has been realized by increasing the strength of the applied magnetic field during compression molding, adopting a transverse magnetic field molding method, or the like. And they function well, and high magnetic properties exceeding 398 kJ / m ³ (50 MGOe) are realized.

[0004] A conventional RTB-based sintered magnet will be described below. In order to improve the performance of conventional RTB-based sintered magnets, an alloy prepared by adjusting the melting composition to match the optimal main component composition of RTB-based sintered magnets is used. I have been. Furthermore, in order to obtain an alloy structure suitable for high performance, the casting mold has been improved, and the main component composition of the RTB-based sintered magnet has been optimized using a rotating roll called a strip cast method. The alloy melt adjusted to the same melting composition is quenched and solidified, and R-T- which does not generate primary crystal α-Fe
A method for obtaining a B-based alloy (Japanese Patent No. 2750442) is also used for industrial production. Next, the melted RTB-based alloy is subjected to mechanical coarse grinding or HD treatment (Hydrogen Dec.).
(pulverization) by a coarse pulverization method utilizing hydrogen storage called hydrogen repitation. Next, the coarse powder is finely pulverized to obtain a finely pulverized powder having an average particle diameter of 3 to 5 μm. As a fine pulverizing means, an organic solvent having an oxidation resistance-imparting action, a wet fine pulverization method in which a steel ball of a pulverizing medium and the coarse powder are blended by a predetermined amount and then pulverized by being charged into a pulverizing cylinder such as a vibration mill or a wheel mill, or A dry pulverization method such as pulverizing the coarse powder with a high-pressure inert gas jet of a jet mill is useful. In particular, seat mills are frequently used. Usually, the finely pulverized powder has a particle size distribution of 0.2 to several tens of μm, but it is desirable to control the particle size distribution to 0.5 to 10 μm in order to enhance magnetic properties. Next, molding is performed in a magnetic field. In order to increase (BH) max, the higher the applied magnetic field strength, the higher the degree of orientation of the molded body, which is desirable.
5.8 to 1193.7 kA / m (10 to 15 kOe) is practical. Next, the molded body is, for example, 1020 to 1100 ° C. x 1 to 5 in vacuum.
Heat and sinter for hours. Thereafter, the sintered body is subjected to a heat treatment to obtain a sintered body having a high iHc. It is practical to perform the heat treatment in two steps in an inert gas atmosphere. The first stage heat treatment is 850-950 ℃ x1
~ 5 hours, the second stage heat treatment is 400 ~ 600 ℃ x1
Heating conditions of ~ 5 hours are preferred, followed by cooling to room temperature. The anisotropic magnetic field of the conventional RTB-based sintered magnet manufactured under such conditions is converted to a SPD (Singular Point Det
FIG. 1 shows the results of the actual measurement by the ection) method. As shown in FIG. 1, the anisotropic magnetic field of the conventional RTB based sintered magnet is represented by one peak magnetic field strength (H). The SPD method draws a 4πI (magnetization intensity) -H (magnetic field intensity) curve in two directions perpendicular to the orientation direction and the orientation direction of the RTB based sintered magnet to be measured. This is a method of obtaining an anisotropic magnetic field by differentiating twice with H. The magnetic field strength indicating a peak is the anisotropic magnetic field (HA).
and S. Rinaldi: J. Appl. Phys. 45 (1974), 3600.

[0005]

In order to further improve the performance of the RTB-based sintered magnet, Br (iHc) is improved while maintaining high iHc (Br) equal to or higher than the conventional one. It is necessary. Therefore, an object of the present invention is to provide an RTB based sintered magnet in which Br (iHc) is improved while maintaining high iHc (Br) equal to or higher than the conventional one.

[0006]

The RTB-based sintered magnet of the present invention has a non-uniform anisotropic magnetic field distribution related to the crystal magnetic anisotropy of the main phase as compared with the conventional one. Br (iHc) is improved while maintaining high iHc (Br) equal to or higher than that. Specifically, for example, two or more types of coarse or fine powder of an RTB-based alloy in which the main components are matched except that the content of heavy rare earth elements such as Dy is changed and only the configuration of the R component is changed. It is manufactured by performing molding and subsequent steps using the blended raw materials. It is known that the main phase crystal grains of the sintered magnet of the present invention thus manufactured have the following three types of heavy rare earth element concentration distributions. The first type is a case where the surface layer portion and the core portion of the main phase crystal grains have substantially the same heavy rare earth element concentration. The second type is a case where the concentration of heavy rare earth elements in the core portion is significantly higher than that in the surface layer portion in the main phase crystal grains. Third
The second type is a case where the concentration of heavy rare earth elements in the surface layer is significantly higher than that in the core in the main phase crystal grains. The occurrence frequency of these three types of main phase crystal grains depends on the uneven distribution state of the heavy rare earth element component in two or more of the RTB-based alloy fine powders constituting the compact, and the mutual diffusion of the heavy rare earth element component by sintering. Is determined by the degree of uniformity. Dy ₂ Fe ₁₄ B type compared to Nd ₂ Fe ₁₄ B type,
Tb ₂ Fe ₁₄ B-type or Ho ₂ Fe ₁₄ B-type intermetallic compounds have a small saturation magnetization but a large anisotropic magnetic field. The distribution of the anisotropic magnetic field attributed to these main phases is as described in the above 3
It is determined that the occurrence occurs reflecting the uneven distribution of the heavy rare earth element component (fluctuation in the concentration of heavy rare earth element) in the main phases. FIG. 2 shows the distribution of the anisotropic magnetic field (HA) of the RTB based sintered magnet of the present invention. In FIG. 2, HA (lower) is H
HA (higher) refers to the higher one of the peak values of the A distribution. Distribution width of anisotropic magnetic field: d (HA) is d
(HA) = HA (higher)-HA (lower). In order to obtain an RTB-based sintered magnet with improved Br (iHc) while maintaining high iHc (Br) equal to or higher than the conventional value, d (HA) must be 15
It must be 9.2kA / m (2kOe) or more.

[0007] In the RTB based sintered magnet of the present invention,
Br that the average crystal grain size of the main phase crystal grains is 6 to 9 μm,
Preferred for increasing iHc. When the average crystal grain size exceeds 9 μm, the squareness of the demagnetization curve is significantly deteriorated. More preferably, the average crystal grain size of the main phase crystal grains is 6 to 9 μm and the maximum diameter of the main phase crystal grains is 14 μm or less. If the maximum diameter of the main phase crystal grains exceeds 14 μm, buds of reverse magnetic domains are generated from the large phase main crystal grains at the time of a low applied magnetic field strength, resulting in a decrease in squareness and iHc. Average grain size is 6μm
If it is less than 1, the orientation and the like of the molded body are reduced, and the (BH) max of the finally obtained sintered magnet is significantly reduced.

The reasons for limiting the main component composition of the RTB based sintered magnet of the present invention will be described below. The main components R, B and T
R: 28.8-33%, B: 0.9
It is preferable to set the content to 1.2% and the balance T. Below, simply%
Indicates weight%. If the R amount is less than 28.8%
iHc decreases, and if it exceeds 33%, Br decreases. It is practical to construct R mainly with Nd and Pr,
Ratio of d and Pr: Pr / (Nd + Pr) = 0.1 to 50%
And (Nd + Pr) / R ≧ 90%. In particular, Nd: Pr at a weight ratio called Didimium
The alloy of = 2: 1 is a low-cost mixed rare earth alloy which does not require separation of pure elements of Nd and Pr having similar chemical properties.
In order to realize the distribution of the anisotropic magnetic field of the present invention, the content of the heavy rare earth element is preferably set to 0.02 to 10%. If the content of the heavy rare earth element is less than 0.02%, the effect of addition is not recognized, and if it exceeds 10%, the reduction of Br becomes remarkable. B content is 0.9-1.2
% Is preferable, and 0.95 to 1.15% is more preferable. B content is 0.
If it is less than 9%, it becomes difficult to use the R ₂ T ₁₄ B type intermetallic compound as a main phase, and if it exceeds 1.2%, B-rich nonmagnetic R
The phase such as Fe ₆ B ₆ increases, and (BH) max decreases remarkably. It is preferable to contain 0.1 to 5% of Co. Co
If the amount is less than 0.1%, it is difficult to improve the Curie point and corrosion resistance, and if it exceeds 5%, the reduction of Br, iHc and (BH) max becomes remarkable. By containing 0.02 to 1% of Ga, the coercive force can be significantly improved. If the Ga content is less than 0.02%, the effect of addition is not recognized, and if it exceeds 1%, the effect of improving the coercive force is saturated and the decrease in Br becomes large. Cu to 0.
It is effective to improve the coercive force by containing 01 to 1%,
If it is less than 0.01%, the effect of addition is not recognized, and if it exceeds 1%, the reduction of Br becomes large. It is effective to contain 0.01 to 1% of Al, but if it is less than 0.01%, the effect of addition is not recognized.
%, The Br is greatly reduced. Preferably, Nb is contained in an amount of 0.05 to 1.5%. Nb is added in the sintering process by adding Nb.
Of the main phase suppresses abnormal grain growth. When the Nb content is less than 0.05%, the effect of addition is not recognized, and when the Nb content is more than 1.5%, the amount of Nb boride formed increases and Br
Greatly decreases.

The melting composition of the two or more RTB-based alloys used as raw materials for the RTB-based sintered magnet of the present invention is adjusted by high-frequency melting or arc melting. It is obtained by solidifying a molten metal by a mold casting method or a strip casting method. Alternatively, as an inexpensive production method, the two or more types of R-
A TB alloy may be produced. Among them, the two or more RTB-based alloys produced by the strip cast method are particularly a rare earth rich phase as the second phase and a B-phase as the third phase.
It is excellent in dispersibility of rich phase and does not produce primary crystal α-Fe which is observed in ingots produced by mold casting. In the case of using a cast iron ingot, it is necessary to perform a homogenizing heat treatment (1050 to 1150 ° C. × 0.5 to 10 hours) in an Ar gas atmosphere before pulverization to eliminate primary crystal α-Fe. Further, the two or more kinds of strip-cast RTB-based alloys are as ca
Although it may be subjected to pulverization in the state of st, the main phase crystal grains are slightly coarsened by performing heat treatment under the same conditions as the above homogenization heat treatment, and the orientation degree of the molded body molded in the magnetic field is increased. (BH) max of the RTB-based sintered magnet obtained in (1) may be increased.

As described above, in order to realize the distribution of HA of the present invention, (1) a first method is to use two types of RTB-based alloy coarse powders, for example, as shown in Examples described later. This is a method for producing an RTB based sintered magnet of the present invention using a mixture of the above. That is, the content of the R element of both is made the same, and the content of the heavy rare earth element in the first alloy coarse powder is reduced from 0 to 10.
The content of the heavy rare earth element in the second alloy coarse powder is more than 10% by weight and 40% by weight or less. In this case, the mixing ratio of the first alloy coarse powder / the second alloy coarse powder is 50/50 to 95 /
It is preferably set to 5, more preferably 70/30 to 95/5, and particularly preferably 80/20 to 90/10. This is because the greater the difference in the content of heavy rare earth elements between the first alloy coarse powder and the second alloy coarse powder, the finer the difference between the first alloy coarse powder and the second alloy coarse powder. The difference in grindability (particle size distribution of fine powder) increases, and the particle size distribution of the main phase crystal grains of the finally obtained RTB based sintered magnet becomes wider, improving the magnetic properties as compared with the past. It becomes difficult to do so. (2) In the second method, for example, two kinds of R-T-B alloys prepared by separately pulverizing the two kinds of RTB-based alloy coarse powders of (1) are used.
In this method, a mixture of -TB alloy fine powder is used. Also in this case, the mixing ratio of the first alloy fine powder / the second alloy fine powder is preferably 50/50 to 95/5 by weight, and 70/3
It is more preferably 0 to 95/5, and particularly preferably 80/20 to 90/10. The average crystal grain size of the main phase crystal grains of the RTB based sintered magnet produced by the above first or second method is as fine as 6 to 9 μm, and the heavy rare earth in the main phase crystal grains as described above. It has a remarkable HA distribution reflecting the degree of uneven distribution of elemental components, and it is judged that Br and / or iHc can be improved as compared with the related art.

In the present invention, the magnetic properties excluding the anisotropic magnetic field were measured at 20 ° C. using a self-recording magnetometer after magnetizing with a magnetizing magnetic field of 1990 kA / m (25 kOe). The density measurement was performed by an underwater displacement method.

The RTB-based sintered magnet of the present invention is subjected to a known surface treatment and put to practical use.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to examples, but the present invention is not limited by these examples. Example 1 An alloy was prepared by casting an alloy melt prepared by arc melting so as to have the alloy compositions of (1) and (2), respectively, into a mold to produce an ingot. Next, the ingot of the alloy (1) was subjected to a homogenizing heat treatment at 1000 ° C. for 5 hours in an Ar gas atmosphere, and cooled to room temperature. The ingot of the alloy (2) was subjected to a homogenizing heat treatment at 1050 ° C. × 5 hours in an Ar gas atmosphere and cooled to room temperature. As a result of the heat treatment, α-Fe disappears and the main phase crystal grains grow a little, so that the fine powder particles after the pulverization become substantially main phase single crystal particles and a good degree of orientation of the molded body can be realized. Was. Next, the heat-treated incot was subjected to hydrogen pulverization (Hydrogen Decrepitation), and then sieved through a 32-mesh (400 μm) antenna to obtain a coarse powder composed of the alloys (1) and (2). The oxygen content of the alloy coarse powder of (1) is 1450 ppm,
The oxygen content of the alloy coarse powder of (2) was 1300 ppm. Alloy (1); Nd: 32.5%, B: 1.00%, Ga: 0.08%,
Fe: bal. Alloy (2); Nd: 19.5%, Dy: 13.0%, B: 1.00%,
Ga: 0.08%, Fe: bal. Next, 89.2 parts by weight of the coarse powder of the alloy (1) and 10.8 parts by weight of the coarse powder of the alloy (2) were mixed and then mixed by a mixer. Next, the mixed coarse powder was finely pulverized with a shear mill using nitrogen as a pulverizing medium under a pulverizing pressure of 68.6 × 10 ⁴ Pa (7 kg / cm ² ) to obtain a fine powder having an average particle diameter of 3.9 μm. Using this fine powder, the orientation magnetic field strength is 1034.5 kA by the transverse magnetic field molding method (the molding method in which the orientation magnetic field and the molding pressure are almost perpendicular).
/ m (13 kOe) and molding pressure: 9.8 × 10 ⁷ Pa (1 ton / cm ² ). Then, the shaped body about 4 × 10 ^-3 Pa
(3 × 10 ⁻⁵ Torr), sintered at 1080 ° C. for 2 hours, and cooled to room temperature to obtain a sintered body having a sintered body density of approximately 7.6 Mg / m ³ (7.6 g / cm ³ ). Next, the sintered body was subjected to a two-step heat treatment in an Ar gas atmosphere. After the first-stage heat treatment was performed at 900 ° C. for 2 hours, the second-stage heat treatment was performed at 550 ° C. for 1 hour, and then cooled to room temperature. After processing the obtained sintered magnet material into a predetermined shape, the main components were analyzed. As a result, Nd: 30.85%, Dy: 1.40%, B: 1.00%,
Ga: 0.08%, Fe: bal., Oxygen content is 3900pp
m. Next, an epoxy resin was coated to an average thickness of 5 μm by electrodeposition to obtain an R—Fe—B based sintered magnet of the present invention. As a result of measuring the magnetic properties of this sintered magnet, Br =
1.38T (13.8kG), bHc = 1058.4kA / m (13.3kOe), iHc =
1201.7 kA / m (15.1 kOe), (BH) max = 362.2 kJ / m
³ (45.5MGOe). Next, as a result of measuring the anisotropic magnetic field by the SPD method using a pulse magnetic field, the distribution of the anisotropic magnetic field was 6286.8 to 6525.6 kA / m (79 to 82 kOe), and the distribution width: d (HA) = 238.7 kA / m (3 kOe), and the average crystal grain size of the main phase was 8.0 μm.

(Conventional Example 1) An alloy melt prepared by arc melting so as to have the alloy composition of (3) is cast into a mold.
An incot was prepared. Alloy (3); Nd: 30.85%, Dy: 1.40%, B: 1.00%,
Ga: 0.08%, Fe: bal. This ingot was subjected to a homogenizing heat treatment at 1050 ° C. × 5 hours in an Ar gas atmosphere and cooled to room temperature. Next, the heat-treated incot was subjected to hydrogen pulverization (Hydrogen Decrepitation), and then sieved through a 32-mesh (400 μm) antenna to obtain a coarse powder composed of the alloy (3). Except that this coarse powder was used, pulverization, molding, sintering, heat treatment, machining, and electrodeposition epoxy resin coating were performed in the same manner as in Example 1 to obtain a conventional R-Fe-B-based sintered magnet. Was. The magnetic properties of this sintered magnet are Br = 1.35
T (13.5 kG), bHc = 1026.6 kA / m (12.9 kOe), iHc = 1153.9 kA
/ m (14.5 kOe) and (BH) max = 346.3 kJ / m ³ (43.5 MGOe). The main component composition of this sintered magnet is Nd: 3
0.85%, Dy: 1.40%, B: 1.00%, Ga: 0.08%, F
e: bal., and the oxygen content was 3980 ppm. The peak of the anisotropic magnetic field (HA) was one point, and the peak was located at 6366.4 kA / m (80 kOe).

(Example 2) Alloy (4); Nd: 25.22%, Pr: 7.03%, B: 1.05%,
Ga: 0.14%, Al: 0.15%, Fe: bal. Alloy (5); Nd: 8.02%, Pr: 2.23%, Dy: 22.00
%, B: 1.05%, Ga: 0.14%, Al: 0.15%, F
e: Alloys (4) and (5) each having a main component composition of bal. were produced by a strip casting method. Next, a homogenization heat treatment, hydrogen pulverization, and sieving were carried out in the same manner as in Example 1 except that the alloys (4) and (5) were used, respectively, to obtain coarse powder. Next, using the obtained coarse powders of the alloys (4) and (5), they were mixed at a mixing ratio shown in Table 1. Table 1 shows the analysis values of the mixed coarse powders (a) to (d).
Next, an R—Fe—B based sintered magnet was prepared and evaluated in the same manner as in Example 1 except that the mixed coarse powders (a) to (d) were used. Table 2 shows the results.

[0016]

[Table 1]

[0017]

[Table 2]

(Conventional Example 2) Alloy (6); Nd: 24.13%, Pr: 6.72%, Dy: 1.40
%, B: 1.05%, Ga: 0.14%, Al: 0.15%, F
e: bal. alloy (7); Nd: 23.73%, Pr: 6.62%, Dy: 1.90
%, B: 1.05%, Ga: 0.14%, Al: 0.15%, F
e: bal. alloy (8); Nd: 23.56%, Pr: 6.51%, Dy: 2.38
%, B: 1.05%, Ga: 0.14%, Al: 0.15%, F
e: bal. alloy (9); Nd: 22.95%, Pr: 6.40%, Dy: 2.90
%, B: 1.05%, Ga: 0.14%, Al: 0.15%, F
e: bal. A molten metal adjusted to the respective compositions of alloys (6) to (9) was prepared by arc melting and then rapidly solidified by a strip casting method to prepare alloys (6) to (9). A conventional sintered magnet was prepared and evaluated in the same manner as in Example 2 except that the individual coarse powders of these alloys (6) to (9) were used. Table 3 shows the results.

[0019]

[Table 3]

FIG. 3 shows the relationship between Br and iHc among the results in Tables 1 to 3. From the results of Tables 1 to 3, the sintered magnet of Example 2 in which the distribution of the anisotropic magnetic field: d (HA) is 159.2 kA / m (2 kOe) or more, shows that the distribution of the anisotropic magnetic field: d (HA) It can be seen that (BH) max and the like are higher than those of Conventional Example 2 where = 0.

Example 3 Alloy (10); Nd: 25.22%, Pr: 7.03%, B: 1.05
%, Ga: 0.14%, Al: 0.13%, Fe: bal. Alloy (11); Nd: 11.93%, Pr: 3.32%, B: 1.05
%, Ga: 0.14%, Dy: 17.00%, Al: 0.13%, F
e: bal. Alloys (10) and (11) were prepared by strip casting method, respectively.
Coarse. Using the coarse powders of the alloys (10) and (11), they were mixed at the mixing ratios shown in Table 4, respectively, to prepare coarse powders (e) to (m).
Table 4 shows the analysis values of each mixed coarse powder. Sintered magnets were prepared and evaluated in the same manner as in Example 1 except that each of the mixed coarse powders was used. Table 5 shows the results. Also, the SPDs described in Table 5
(Higher) and HA (lower) and D measured by the method
FIG. 4 shows the relationship with the y content. FIG. 4 shows that d (HA) increases as the Dy content increases.

[0022]

[Table 4]

[0023]

[Table 5]

(Conventional Example 3) Alloy (12); Nd: 24.13%, Pr: 6.72%, Dy: 1.40
%, B: 1.05%, Ga: 0.14%, Al: 0.10%, F
e: bal. alloy (13); Nd: 23.73%, Pr: 6.62%, Dy: 1.90
%, B: 1.05%, Ga: 0.14%, Al: 0.10%, F
e: bal. alloy (14); Nd: 23.56%, Pr: 6.51%, Dy: 2.38
%, B: 1.05%, Ga: 0.14%, Al: 0.10%, F
e: bal. alloy (15); Nd: 22.95%, Pr: 6.40%, Dy: 2.90
%, B: 1.05%, Ga: 0.14%, Al: 0.10%, F
e: bal. alloy (16); Nd: 22.09%, Pr: 6.16%, Dy: 4.00
%, B: 1.05%, Ga: 0.14%, Al: 0.10%, F
e: bal. alloy (17); Nd: 21.31%, Pr: 5.94%, Dy: 5.00
%, B: 1.05%, Ga: 0.14%, Al: 0.10%, F
e: bal. alloy (18); Nd: 20.53%, Pr: 5.72%, Dy: 6.00
%, B: 1.05%, Ga: 0.14%, Al: 0.10%, F
e: bal. alloy (19); Nd: 19.75%, Pr: 5.50%, Dy: 7.00
%, B: 1.05%, Ga: 0.14%, Al: 0.10%, F
e: bal. alloy (20); Nd: 18.97%, Pr: 5.28%, Dy: 8.00
%, B: 1.05%, Ga: 0.14%, Al: 0.10%, F
e: Alloys (12) to (20) were prepared by bal. strip casting method and coarsened. Example 3 except that each of these single coarse powders was used.
A conventional sintered magnet was prepared and evaluated in the same manner as described above. Table 6 shows the results. As shown in Table 6, it was found that these conventional sintered magnets had d (HA) = 0.

[0025]

[Table 6]

(Example 4) Alloy (21); Nd: 25.22%, Pr: 7.03%, B: 0.95
%, Ga: 0.14%, Al: 0.10%, Co: 1.00%, C
u: 0.03%, Nb: 0.20%, Fe: bal. alloy (22); Nd: 13.02%, Pr: 2.23%, Dy: 17.00
%, B: 0.95%, Ga: 0.14%, Al: 0.10%, C
o: 1.00%, Cu: 0.03%, Nb: 0.20%, Fe: ba
l. Using alloys (20) and (21) having the following compositions, coarse powders (p) to (q) mixed at the mixing ratio shown in Table 7 were produced. Table 7 shows the analysis values of these coarse powders. Next, a sintered magnet was prepared and evaluated in the same manner as in Example 1 except that each of the mixed coarse powders shown in Table 7 was used. Table 8 shows the results.

[0027]

[Table 7]

[0028]

[Table 8]

(Conventional Example 4) Alloy (23); Nd: 24.56%, Pr: 6.84%, Dy: 0.85
%, B: 0.95%, Ga: 0.14%, Al: 0.10%, C
o: 1.00%, Cu: 0.03%, Nb: 0.20%, Fe: ba
l. Alloy (24); Nd: 24.12%, Pr: 6.72%, Dy: 1.40
%, B: 0.95%, Ga: 0.14%, Al: 0.10%, C
o: 1.00%, Cu: 0.03%, Nb: 0.20%, Fe: ba
l. Alloy (25); Nd: 23.73%, Pr: 6.62%, Dy: 1.90
%, B: 0.95%, Ga: 0.14%, Al: 0.10%, C
o: 1.00%, Cu: 0.03%, Nb: 0.20%, Fe: ba
l. Alloy (26); Nd: 23.56%, Pr: 6.51%, Dy: 2.40
%, B: 0.95%, Ga: 0.14%, Al: 0.10%, C
Alloys (23) to (26) having compositions of o: 1.00%, Cu: 0.03%, Nb: 0.20%, and Fe: bal. were prepared by a strip casting method and coarsened. Sintered magnets were prepared and evaluated in the same manner as in Example 4 except that the individual coarse powders of the alloys (23) to (26) were used. Table 9 shows the results.

[0030]

[Table 9]

Example 5 Alloy (27); Nd: 30.5%, Pr: 1.20%, B: 0.97
%, Ga: 0.14%, Al: 0.10%, Fe: bal. Alloy (28): Nd: 19.0%, Pr: 0.70%, Dy: 12.0
%, B: 0.97%, Ga: 0.14%, Al: 0.10%, F
e: Alloys (27) and (28) having the composition of bal. were prepared by a strip casting method and coarsely pulverized. Next, in terms of weight ratio, alloy (27): alloy (28)
= 93.75: 6.25. The composition of this mixed coarse powder is as follows: Nd: 29.78%, Pr: 1.17%, D:
y: 0.75%, B: 0.97%, Ga: 0.14%, Al: 0.10
%, Fe: bal. Next, the powder was finely pulverized with a shear mill to obtain a fine powder having an average particle diameter of 3.7 μm. After filling a predetermined amount of this fine powder into the mold cavity, a pulsed magnetic field of 2387.4 kA / m (30 kOe) was applied twice alternately to the positive and negative sides, and then 795.8 kA / m (10 kOe).
e) While applying the DC magnetic field, the molding pressure is 19.6 × 10 ⁷ Pa (2 tons)
/ cm ² ). Next, the compact was sintered at 1040 ° C. for 3 hours in a vacuum atmosphere. Then, after heating in an Ar gas atmosphere at 900 ° C. for 2 hours, subsequently heating at 560 ° C. for 1 hour,
Subsequently, it was quenched into water. The obtained sintered magnet was processed into a predetermined shape, and the magnetic properties were measured. As a result, Br = 1.390T (13.90k
G), bHc = 1062.4 kA / m (13.35 kOe), iHc = 1173.8 kA
/ m (14.75 kOe), (BH) max = 370.1 × 10 ³ J / m ³ (46.
5MGOe) was obtained. The anisotropic magnetic field distribution is 6167.5
6356350.5 kA / m (77.5 to 79.8 kOe). (Conventional Example 5) Nd: 29.78%, Pr: 1.17%, Dy: 0.7
5%, B: 0.97%, Ga: 0.14%, Al: 0.10%, Fe:
An alloy having a main component composition indicated by bal. was prepared by a strip casting method and then coarsened. A sintered magnet was prepared and evaluated in the same manner as in Example 5 except that this coarse powder was used. The sintering temperature was 1070 ° C. The obtained magnetic properties are Br = 1.355T
(13.55kG), bHc = 1037.7kA / m (13.04kOe), iHc = 108
6.3 kA / m (13.65kOe), (BH) max = 350.2J / m 3 (4
4.0MGOe) with an anisotropic magnetic field of 6183.4 kA / m (77.7 kO
Only one peak was observed in e). FIG. 5 is a view showing a grain size distribution of typical main phase crystal grains of a sintered magnet of Example 5 having an anisotropic magnetic field distribution, and FIG. 6 is a conventional example having no anisotropic magnetic field distribution. 5 is a diagram showing a particle size distribution of typical main phase crystal grains of the sintered magnet of No. 5. FIG. 5 and 6, the grain size of 11 to 12 μm means that the main phase crystal grain is 11 μm.
It represents not less than 12 μm. The particle size on the abscissa is obtained by taking a cross-sectional photograph (magnification: about 1000 times) of the magnet body to be observed using an optical microscope of Model: UFX-II manufactured by Nikon Corporation, Image processing software (Image pro. Pl
us (DOS / V)) was read from a scanner connected to a predetermined personal computer installed with the image processing. Assuming that the area of each main phase crystal grain measured in this image processing is (S), the cross-sectional shape of each main phase crystal grain is a circle, and the particle size (d) of each main phase crystal grain is d = (4 × S / π) ^1/2 was defined. The frequency (%) on the vertical axis is the area ratio of the main phase crystal grains in each particle size range when the total area of the main phase crystal grains in the target visual field is 100%.

In the above embodiment, the case where the heavy rare earth element is Dy is described, but other heavy rare earth elements (Tb or Ho) are used.
In the case where is contained, substantially the same effect as in the above embodiment can be obtained.

[0033]

As described above, according to the present invention, 159.
By having an anisotropic magnetic field distribution of 2 kA / m (2 kOe) or more, the R-
A TB-based sintered magnet can be provided.

[Brief description of the drawings]

FIG. 1 shows an anisotropic magnetic field (HA) of a conventional RTB sintered magnet.
FIG.

FIG. 2 shows an anisotropic magnetic field (H) of the RTB based sintered magnet of the present invention.
It is a figure which shows the distribution of A).

FIG. 3 is a diagram showing an example of the relationship between Br and iHc when the distribution has an anisotropic magnetic field and when it does not.

FIG. 4 is a diagram showing an example of the relationship between Dy concentration and HA (higher), HA (lower).

FIG. 5 is a diagram showing an example of a main phase crystal grain size distribution of the sintered magnet of the present invention.

FIG. 6 is a diagram showing an example of a main phase crystal grain size distribution of a conventional sintered magnet.

Claims (3)

[Claims] 1. An R ₂ T ₁₄ B type intermetallic compound (R is one or more of rare earth elements including Y, and Dy, T
b, Ho, which always contains at least one kind of Ho, and T is Fe or Fe and Co). An RTB based sintered magnet which is distributed and has a distribution width of the anisotropic magnetic field of 159.2 kA / m (2 kOe) or more. 2. When the total of the main components R, T and B is 100% by weight, R is 28.8-33% and R
The RTB-based sintering according to claim 1, wherein the content of one or more of Dy, Tb, and Ho in the steel is 0.2 to 10%, B is 0.9 to 1.2%, and the balance is T. magnet. 3. A method according to claim 1, wherein part of Fe is 0.02-1% Ga, 0.1-0.1%.
5% Co, 0.01-1% Cu, 0.01-1% Al, 0.05
The RTB-based sintered magnet according to claim 1 or 2, wherein the RTB-based sintered magnet is substituted with one or more of Nb of 1.5%.