JP3254232B2 - Manufacturing method of rare earth permanent magnet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a rare earth permanent magnet having excellent magnetic properties and used for various electric and electronic devices.

[0002]

2. Description of the Related Art Among rare earth magnets, Nd-Fe-B magnets are:
In recent years, Nd, which is a main component, is abundant in resources, low in cost, and excellent in magnetic properties, and thus its use has been expanding in recent years. Research and development for improving magnetic properties has been energetically conducted since the invention of the Nd-based magnet, and many studies and inventions have been proposed. Among these Nd-based sintered magnet production methods, there is also a method for producing high-performance Nd magnets by mixing and sintering various metal powders and alloy powders with different compositions (hereinafter simply referred to as the mixing method). Numerous inventions have been proposed.

The mixing methods proposed so far can be roughly classified into the following four types. In the first method, one of the raw material alloy powders to be mixed is made into an amorphous or microcrystalline alloy by a liquid quenching method, and a normal rare earth alloy powder is mixed therewith, or both raw material alloy powders are mixed together. A method of producing and mixing by a liquid quenching method [JP-A-63-93841, JP-A-63-115307, JP-A-63-25
2403, JP-A-63-278208, JP-A-1-108707, JP-A-1-4631
0, JP-A-1-146309 and JP-A-1-155603]. The mixing method using an alloy by the liquid quenching method recently reported magnetic properties exceeding 50 MGOe.
[E.Otuki, T.Otuka and T.Imai; 11th.Int.Workshop onRa
re Earth Magnets, Pittsburgh, Pennsylvania, USA, Octob
er (1990), p. 328].

In a second method, two kinds of raw material alloy powders to be mixed are both made of an alloy mainly composed of an R 2 Fe 14 B compound, and two kinds of alloys in which the kinds and contents of rare earth elements are changed are produced. Mixed sintering method [Japanese Patent Laid-Open No. 61-8160
3, JP-A-61-81604, JP-A-61-81605, JP-A-61-81606,
JP-A-61-81607, JP-A-61-119007, JP-A-61-207546,
See JP-A-63-245, and JP-A-1-177335]. In this method, the phases contained in each alloy are a conventionally known R ₂ Fe ₁₄ B phase, a rare earth rich phase, and Nd ₁ + XFe ₄ B.
_Four phases.

The third method is to use one of the alloys mainly as R ₂
A method of producing an Nd-based rare earth magnet by mixing and sintering various low melting point elements, low melting point alloys, rare earth alloys, carbides, borides, hydrides, and other powders with an alloy powder composed of an Fe ₁₄ B compound. (JP-A-60-230959, JP-A-61-263201, JP-A-62-181402, JP-A-62-182249, JP-A-62-206802, JP-A-62-206802
62-270746, JP-A-63-6808, JP-A-63-104406, JP-A-63-1
14939, JP-A-63-272006, JP-A-1-111843, JP-A-1-1463
08 gazettes].

[0006] A fourth method is a method newly invented by the present inventors, which is characterized by the presence of a special intermetallic compound in the alloy to be mixed [Japanese Patent Application No. 03-159765,
Japanese Patent Application Nos. 03-159766, 03-198476, 03-198479, and 03-259694.

[0007]

There are many points in the prior art mixing process that are not suitable or sufficient to achieve truly excellent magnetic properties in the magnet alloy. For example, in the first method described above, the energy product of the magnet alloy is high but the coercive force is at most about 9
At about kOe, the coercive force decreases with increasing temperature.
Considering the disadvantages unique to Nd magnets, the magnet properties are not practically sufficient. Further, the production by the liquid quenching method is not an industrial method because the cost is too high.

In the second method, a phase coexisting with the two raw alloy powders is an R ₂ Fe ₁₄ B compound and Nd ₁ + XFe ₄
B ₄ phase. These phases are basically the same as the phases that exist in a manufacturing method using one kind of alloy, and the only difference is the existence ratio between the two alloys. In addition, the melting point of the Nd-rich phase is as low as 750 ° C or less, and becomes a liquid phase before reaching the sintering temperature. Therefore, the liquid phase is oxidized by the oxygen gas in the atmosphere, and high magnetic properties cannot be obtained.

In the third method, there is a proposal to improve the magnetic properties by using a low-melting element or an alloy in the powder to be mixed. This is based on the idea that nucleation sites such as lattice defects and oxide phases existing at the grain boundaries of the R ₂ Fe ₁₄ B compound are removed and the grain boundaries are cleaned to improve the coercive force. However, the presence of the low melting point phase is actually a disadvantageous condition for improving the magnetic properties.
If the low-melting phase becomes a melt from around 600 ° C, for example,
At an actual sintering temperature of 1,100 ° C, the viscosity of the low melting point phase becomes considerably small. As a result, the viscosity of the melt surrounding the magnetic particles decreases, and the rotation of the particles easily occurs, the orientation is disturbed, and the magnetic characteristics are deteriorated. Further, similarly to the second method, the liquid phase at a low temperature is easily oxidized and high magnetic properties cannot be obtained. In the fourth method, an Nd-rich phase having a low melting point exists as one of the phases existing in equilibrium in the B alloy. Since this phase becomes a liquid phase at a low temperature, it is affected by oxidation as in the other cases, and the magnetic properties are degraded. As described above, in the mixing method according to the related art, various roles related to the liquid phase component are sufficiently considered, and the liquid phase alloy component and the melting point are not appropriately adjusted so that these conditions are optimal. An object of the present invention is to improve the drawbacks of the conventional method for producing Nd magnets by a mixing method, and to provide a method for producing rare earth permanent magnets having excellent balanced magnetic properties.

[0010]

In order to solve this problem, the present inventors have basically reviewed the conventional mixing method, and have found that it is sufficient to appropriately select and combine the types and characteristics of the constituent phases of the magnetic material. The present inventors have found that satisfactory and balanced magnetic properties can be obtained, and have studied the manufacturing conditions in detail to complete the present invention. The gist of the present invention is that the A alloy is mainly an R ₂ T ₁₄ B phase [where R is at least one or more rare earth elements mainly composed of Nd, Pr and Dy, and T is mainly composed of Fe or Fe and Co. Represents at least one transition metal], and the B alloy is a CeCo ₄ B-type composition formula RFeCoM ¹ M ² whose crystal structure is represented by a space group of P6 / mmm [where R is Nd, Pr, D
at least one or more rare earth elements mainly composed of y, M ¹
Are Al, Cu, Zn, In, Si, P, S, Ti,
V, Cr, Mn, Ni, Ga, Ge, Zr, Nb, M
o, Pd, Ag, Cd, Sn, Sb, Hf, Ta, 1 or two or more elements selected from among W, ^{M 2} is, B,
Represents one or more elements selected from C, N, and O] , and has a melting point of 750 ° C or more and 2,000 ° C or less.
As an alloy mainly composed of an intermetallic compound, B alloy powder is 1 to 4 wt% based on 99 to 60 wt% of A alloy powder.
0% by weight, press-forming the mixed powder in a magnetic field, sintering the formed body in a vacuum or an inert gas atmosphere, and further heat-treating at a low temperature not higher than the sintering temperature. a method for producing a magnet, more specifically, the intermetallic compound having the composition formula RFeCoM ¹ M ² is B alloy, the composition formula ^{_{R a Fe b Co c M 1}} d M 2 e [ here subscripts a, b,
c, d and e are atomic% of each element, 13 ≦ a ≦ 26, 0 <
b ≦ 60, 20 ≦ c ≦ 80, 0 ≦ d ≦ 40, 1 ≦ e ≦ 4
5 in which the total of the rare earth elements contained in the mixed powder of the A alloy and the B alloy is 10 to 10.
15 atomic% der is, the average particle diameter of the mixed powder is made by mixing A alloy powder and B alloy powder, or these, 0.
A method for producing a rare earth magnet, wherein the thickness is 2 to 30 μm.

Hereinafter, the present invention will be described in detail. The present invention
This is a method for producing a rare-earth permanent magnet in which an alloy mainly containing an R ₂ Fe ₁₄ B phase is mixed with an alloy powder containing an intermetallic compound having a specific crystal structure (hereinafter, referred to as a compound powder mixing method). The alloy A, which is a raw material, is mainly composed of an R ₂ Fe ₁₄ B compound phase, and R represents La, Ce, Pr, Nd, Sm, Eu, and Y containing Y.
Nd, P selected from Gd, Tb, Dy, Ho, Er, Yb and Lu
At least two or more rare earth elements mainly composed of r and Dy. T represents Fe or at least one or more transition metals mainly composed of Fe and Co, and the Co content is 0 to 40% by weight. The addition of Co increases the Curie temperature of the A alloy and also improves the corrosion resistance of the alloy. The alloy A is prepared by melting a raw metal in a vacuum or an inert gas, preferably an Ar atmosphere. As a raw material metal, a pure rare earth element or a rare earth alloy, pure iron, ferroboron, or an alloy thereof is used, but a trace impurity inevitable in general industrial production is included. In the obtained ingot, since the R ₂ Fe ₁₄ B phase is formed by the peritectic reaction between αFe and the rare earth rich phase, the αFe phase, the R rich phase, the B rich phase, the Nd ₃ Co phase, etc. May remain. In the present invention, R ₂ Fe _{14 in} alloy A is used.
Since it is desirable to have more B phases, a solution treatment is performed if necessary. The condition is 700 ~ 1, under vacuum or Ar atmosphere.
The heat treatment may be performed in a temperature range of 200 ° C. for 1 hour or more.

CeCo ₄ B having a crystal structure represented by a space group of P6 / mmm with respect to 99 to 60% by weight of the A alloy powder.
Composition formula RFeCoM ¹ M ² [where R is Nd, P
At least one or more rare earth elements mainly composed of r and Dy, and M ¹ are Al, Cu, Zn, In, Si, P, S,
Ti, V, Cr, Mn, Ni, Ga, Ge, Zr, N
b, Mo, Pd, Ag, Cd, Sn, Sb, Hf, T
one or more elements selected from a and W, M ²
Represents one or more elements selected from among B, C, N, and O] , and has a melting point of 750 ° C. or more and 2,000
A B alloy powder mainly composed of an intermetallic compound having a temperature of 0 ° C. or less is mixed in an amount of 1 to 40% by weight, and the mixed powder is subjected to pressure molding in a magnetic field, and the compact is subjected to vacuum or an inert gas atmosphere. Sinter and heat-treat at low temperature below the sintering temperature. CeC in which the above crystal structure is represented by a space group of P6 / mmm
A o ₄ B-type composition formula RFeCoM ¹ M ^2, the melting point
Various intermetallic compound is 750 ° C. or higher 2,000 ° C. or less, the range indicated composition formula of ^{_{R a Fe b Co c M 1}} d M 2 e [ here subscripts a, b, c, d, e are atomic% And 13 ≦ a
≦ 26, 0 <b ≦ 60, 20 ≦ c ≦ 80, 0 ≦ d ≦ 4
0, 1 ≦ e ≦ 45], and a, b,
The range of c, d and e is such that the crystal structure is P
A CeCo ₄ B type composition formula RFeCoM ¹ M ² represented by a space group of 6 / mmm, having a melting point of 750 ° C. or higher.
It is determined from the fact that the intermetallic compound having a temperature of 000 ° C. or lower is stably present. If the intermetallic compound is out of this range, these intermetallic compounds do not exist and high magnetic properties cannot be obtained. The alloy B is weighed and melted in a vacuum or an inert gas, preferably an Ar atmosphere, and cast.
Raw material metals are pure rare earth elements or rare earth alloys, pure iron,
Ferroboron, various pure metals, and alloys thereof are used, but shall contain trace impurities inevitable in general industrial production. If there is solidification segregation, the obtained ingot is subjected to a solution treatment if necessary. The conditions are 700-1500 ° C. in a vacuum or Ar atmosphere.
The heat treatment may be performed for one hour or more in the above temperature range.

The above-mentioned various intermetallic compounds can be produced by heat-treating a ribbon having a predetermined composition obtained by the liquid quenching method. In other words, in the liquid quenching method, the alloy after quenching is amorphous or fine crystal, but when this is heated at a temperature higher than the crystallization temperature for a certain period of time,
The quenched alloy is crystallized or recrystallized, and as a result, the various intermetallic compound phases required for the present invention can be precipitated. Therefore, even in a mixing method using an amorphous alloy powder by a liquid quenching method, if the amorphous phase is crystallized before sintering proceeds and the above-mentioned intermetallic compounds necessary for the present invention appear, the present invention Can be regarded as the same method as the method by As described above, the raw materials used in the present invention use materials used in ordinary industrial production, and therefore include impurity elements inevitable in the production method of industrial production. For example, element C, which is the most typical industrial impurity, is present in any of the alloys of the present invention in a range of 0.01 to 0.
It is contained in the range of 3% by weight. The manufacturing method of the magnet according to the present invention uses a powder metallurgy method using fine powder as a basic manufacturing method. Therefore, although atmosphere control such as gas replacement is performed in each step, it is difficult to completely prevent material oxidation due to an increase in powder surface area and activation of the surface. Typically, 0.05
Contains oxygen in the range of ~ 0.6% by weight.

In the present invention, as described above, a high magnetic property can be obtained by mixing the B alloy powder with the A alloy powder at a predetermined ratio. Hereinafter, the reason why the compound powder mixing method of the present invention provided high magnetic properties will be described. First, as a first reason, a CeCo ₄ B-type composition formula RFeCoM whose crystal structure is represented by a space group of P6 / mmm.
The melting point of the ¹ M ² intermetallic compound phase is that the 2,000 ° C. or less suitable 750 ° C. or higher for liquid phase sintering of the Nd-based rare earth magnet. This temperature range is higher than the melting point of the so-called Nd-rich phase. In the conventional Nd magnet manufacturing method and the mixing method other than the present method, since the Nd-rich phase having a low melting point is present, the viscosity of the Nd-rich phase melt is too low at the sintering temperature, and the orientation of the particles is disturbed. And sufficient magnetic characteristics cannot be obtained. Further, since the liquid phase is changed from a low temperature, it reacts with oxygen, moisture and the like in the atmosphere during the temperature raising process. As a result, the liquid phase contains a large amount of oxide, so that the grain boundary cannot be sufficiently cleaned, and high magnetic properties cannot be obtained. In the present invention, the added alloy is made of CeC whose crystal structure is represented by a space group of P6 / mmm.
A o ₄ B-type composition formula RFeCoM ¹ M ^2, the melting point
By using an alloy mainly containing an intermetallic compound phase at 750 ° C. or more and 2,000 ° C. or less, it is possible to prevent the Nd-rich phase having a low melting point from being contained in the powder mixed with the A alloy. Therefore, the influence of the atmosphere on the sintering process is reduced, and high magnetic properties can be obtained.

The second reason is that the corrosion resistance is improved by adding Co. Alloys and compounds added in the mixing method generally contain a larger amount of rare earth elements than the base alloy, and thus are susceptible to oxidative deterioration in the state of fine powder. However, by using a Co-containing intermetallic compound as in the production method of the present invention, the oxidative deterioration of these fine powders can be prevented, and thus stable magnetic properties can be obtained. Generally, a large amount of moisture is attached to the surface of metal fine powder by physical adsorption or chemical adsorption. Fine powder of a rare earth alloy having strong activity is no exception, and a large amount of moisture in the air is adsorbed on the surface. This water cannot be removed only by vacuum evacuation of the sintering furnace, and reacts with the fine powder during the heating to form various hydroxides and oxides. In the compound powder mixing method of the present method, the corrosion resistance of the alloy powder is improved by adding Co to the added intermetallic compound phase containing a large amount of rare earth elements, and as a result, the oxidative deterioration of the fine powder during the sintering process is reduced. And excellent magnetic characteristics can be stably obtained. The third reason is that various alloy elements effective for improving the coercive force are not contained in the A alloy in a large amount but are contained in the intermetallic compound phase to be added. Pr, Dy, and T are effective elements for improving the coercive force of Nd magnets.
Although b, Ga, Al, Cu and other elements are known, they improve the coercive force, but decrease the value of saturation magnetization, which is important for magnet performance, in proportion to the amount of addition. When a large amount of these elements is contained in the R ₂ Fe ₁₄ B phase, which is a ferromagnetic phase, the coercive force increases but the residual magnetic flux density decreases. The coercive force of an Nd magnet is greatly affected by the nature of the crystal grain boundaries of the Nd magnet. Therefore, when the crystal grain boundaries of the magnet alloy become magnetically strong, the domain wall nucleation field at the grain boundaries increases, and the coercive force of the magnet alloy can be improved. It is believed that the above-mentioned various alloy elements increase the magnetic field anisotropy and reduce lattice defects and strain at grain boundaries, thereby increasing the nucleation field of domain walls at grain boundaries. In the present invention, various intermetallic compounds mixed with the A alloy are melted by the alloy itself at the vicinity of the sintering temperature or melted while reacting with the A alloy, and further the diffusion reaction proceeds, and the R ₂ Fe ₁₄ B phase and Nd
Forms a rich phase. By this reaction, a liquid phase is generated near the crystal grain boundaries, and liquid phase sintering is progressed by the liquid phase. However, Pr, Dy, Tb, Ga, Al, Cu and various elements M Will remain in the vicinity of the grain boundaries even after sintering. Therefore, only the vicinity of the crystal grain boundary effective for improving the coercive force of the magnet is magnetically strengthened, and the coercive force is extremely efficiently prevented without lowering the saturation magnetization by penetrating into the R ₂ Fe ₁₄ B phase. Can be improved.

Next, a detailed production method of the compound powder mixing method of the present invention will be described. The A alloy and the B alloy obtained as described above are pulverized into ingots and mixed at a predetermined ratio. The pulverization is performed by wet or dry pulverization.
Rare earth alloys are very active, and are used in an atmosphere such as Ar or nitrogen in the case of dry grinding and in a non-reactive organic solvent such as Freon in the case of wet grinding in order to prevent oxidation during grinding. Done. The mixing step is also performed in an inert gas atmosphere or a solvent as necessary. The pulverization is generally performed stepwise as coarse pulverization and fine pulverization, but mixing may be performed at any stage. That is, a predetermined amount may be mixed after coarse pulverization and then finely pulverized, or may be mixed at a predetermined ratio after all pulverization is completed. It is necessary that the A alloy and the B alloy have approximately the same average particle size and are also uniformly mixed. The average particle size of each powder is preferably in the range of 0.2 to 30 μm. If the average particle size is less than 0.2 μm, the powder tends to be oxidized and deteriorated. If the average particle size exceeds 30 μm, the sinterability deteriorates and high magnetic properties are obtained. No longer available.

The mixing ratio of the A alloy powder and the B alloy powder is
It is better to add and mix in the range of 1 to 40% by weight with respect to 99 to 60% by weight of the alloy powder, and if the B alloy powder is less than 1% by weight,
The sinterability deteriorates, the sintering density cannot be increased, and no coercive force can be obtained. If it exceeds 40% by weight, the proportion of the non-magnetic phase after sintering becomes too large, and the residual magnetic flux density decreases, resulting in high magnetic properties. Characteristics cannot be obtained. The obtained mixed fine powder is then formed into a desired size by a molding press in a magnetic field, and further subjected to a sintering heat treatment. Sintering is performed in a vacuum or argon atmosphere at a temperature in the range of 900 to 1,250 ° C. for 10 minutes or more, followed by heat treatment at a temperature lower than the sintering temperature for 10 minutes or more. The sintered body density of the mixed fine powder after sintering is densified to 95% or more in terms of true density ratio, so that an excellent rare earth magnet having a high residual magnetic flux density, a large coercive force and a good squareness can be obtained.

[0018]

EXAMPLES Hereinafter, specific embodiments of the present invention will be described with reference to examples, but the present invention is not limited thereto. (Example 1, Comparative Example 1) Nd, P having a purity of 99.9% by weight
Al alloy was melt-cast using r, Fe, Co metal and ferroboron in an Ar atmosphere of a high-frequency melting furnace. After casting, this ingot was solution-solutioned at 1,070 ° C. in an Ar atmosphere for 10 hours. The composition of the resulting alloy was 11.0
Nd-1.5Pr-4.5B-1.0Co-bal. F
e (hereinafter each atomic%, bal. represents the atomic% of the remaining elements). Nd, D also having a purity of 99.9% by weight
CeCo ₄ B whose crystal structure is represented by a space group of P6 / mmm using y, Fe, Co metal and ferroboron as raw materials
B1 alloy composed of a mold type intermetallic compound was melt-cast in an Ar atmosphere using a high-frequency melting furnace, and the composition was 8.4 Nd-8.4.
Dy-15.2Fe-16.7B-bal. An alloy of Co was obtained. Each of the ingots A1 and B1 was coarsely pulverized separately in a nitrogen atmosphere to 30 mesh or less. Then, the A1 alloy coarse powder was weighed 89.0% by weight and the B1 alloy was weighed 11.0% by weight. Mix for 30 minutes in the displacement V blender. This mixed coarse powder was finely pulverized with a jet mill using high-pressure nitrogen gas to an average particle size of about 5 μm. The obtained mixed fine powder was press-molded at a pressure of about 1 Ton / cm ² while being oriented in a magnetic field of 15 kOe. Next, the formed body was sintered at 1,070 ° C. for 1 hour in a sintering furnace in an Ar atmosphere, further subjected to aging heat treatment at 530 ° C. for 1 hour, and quenched to prepare Example 1 magnet alloy M1.

For comparison, an alloy having the same composition as that of Example M1 was produced by the conventional one-alloy method, and Comparative Example 1 was used for magnet alloy E1.
And That is, weighing, melting, pulverizing, sintering, and aging heat treatment of one alloy (Comparative Example E1) from the beginning so that the same composition as that obtained by mixing and sintering A1 powder and B1 powder (Example M1) is obtained. Then, the magnetic properties were compared with the magnets obtained by the compound powder mixing method. The composition of this magnet alloy was 10.6 Nd-in both Example M1 by the compound powder mixing method and Comparative Example E1 by the one alloy method.
1.3Pr-1.2Dy-7.9Co-6.2B-0.3O-bal.Fe. This composition is a value obtained by analyzing the final sintered body, and the oxygen contained here is not included as an alloying additive element, but the surface of the fine powder is oxidized during the manufacturing process. It is an impurity that has been mixed in due to However, the amount was adjusted by using a glow box or controlling the atmosphere in both the examples and comparative examples so that the amount would be an industrial value of about 3,000 ppm. Table 1 shows Example M1 and Comparative Example E1.
2 shows the values of the magnetic properties and the sintered body densities obtained for both sintered body magnets. The magnetic properties of the example M1 are almost the same as those of the comparative example E1, but the residual magnetic flux density,
In all the values, such as the coercive force and the maximum energy product, the embodiment M1 is greatly superior. As described above, even if the composition of the magnet alloy is exactly the same, there is a considerable difference in the magnetic properties, indicating that the compound powder mixing method is an extremely effective method for improving the magnetic properties of the Nd magnet. FIG. 1 is an X-ray analysis pattern of a B1 alloy ingot. From now on, the B1 alloy is made of CeCo ₄ whose crystal structure is represented by a space group of P6 / mmm.
It turns out that it mainly consists of a B type intermetallic compound.

(Examples 2 to 6, Comparative Examples 2 to 6) Purity 9
A2-6 alloy was melt-cast using 9.9% by weight of Nd, Pr, Dy, Fe, Co metal and ferroboron in an Ar atmosphere of a high frequency melting furnace. After casting, this ingot was solution-solutioned at 1,070 ° C. in an Ar atmosphere for 10 hours. Tables 2 to 6 show the compositions of A2 to A6 of the obtained alloy. Nd, Dy, Fe also having a purity of 99.9% by weight,
Using Co metal, ferroboron and various metals as raw materials, the crystal structure shown in Tables 2 to 6 is P6 / mmm
B2-6 alloys mainly composed of CeCo ₄ B type intermetallic compounds represented by the following space group were melt-cast in an Ar atmosphere using a high-frequency melting furnace. The composition obtained is also described in the table. A2 to 6 alloys and B2 to 6 alloys were coarsely pulverized separately in a nitrogen atmosphere to 30 mesh or less, and then mixed at the ratio described in the column of mixed weight in the table in a nitrogen-blended V blender. For 30 minutes. This mixed coarse powder is jet-milled using high-pressure nitrogen gas, and has an average particle size of about 5
It was pulverized to μm. The obtained mixed fine powder was press-molded at a pressure of about 1 Ton / cm ² while being oriented in a magnetic field of 15 kOe. Next, the compact was sintered at 1,080 ° C. for 1 hour in a sintering furnace in an Ar atmosphere, and further sintered for 500 hours.
Aging heat treatment at ~ 580 ° C for 1 hour followed by rapid cooling.
Six magnet alloys M2 to M6 were produced.

For comparison, alloys having the same composition as in Examples M2 to M6 were produced by a conventional one-alloy method, and Comparative Examples E2 to E6 were made. That is, weighing, melting, pulverizing, sintering, and aging heat treatment of one alloy (Comparative Examples E2 to 6) from the beginning so as to have the same composition as that obtained by mixing and sintering the A2-6 alloy and the B2-6 alloy. And a magnet prepared by the compound powder mixing method (Examples M2 to M6)
) And magnetic properties were compared. The compositions of the magnet alloys M2 to M6 are described in Tables 2 to 6 in Examples M2 to M6 by the compound powder mixing method and Comparative Examples E2 to E6 by the alloy method. This composition is a value obtained by analyzing the final sintered body, and the oxygen contained here is not included as an alloying additive element, but the surface of the fine powder is oxidized during the manufacturing process. It is an impurity that has been mixed in due to However, the amount was adjusted by using a glow box or controlling the atmosphere in both the examples and comparative examples so that the amount would be an industrial value of about 3,000 to 5,000 ppm. Tables 2 to 6 show the values of the magnetic properties and the sintered body densities obtained for the sintered magnets of Examples M2 to M6 and Comparative Examples E2 to E6. Example M
Although the magnetic properties of the sintered bodies 2 to 6 are almost the same as those of the comparative examples E2 to E6, the density of the sintered bodies is almost the same as that of the comparative examples E2 to E6. Has greatly won. As described above, even if the composition of the magnet alloy is exactly the same, there is a considerable difference in the magnetic properties, indicating that the compound powder mixing method is an extremely effective method for improving the magnetic properties of the Nd magnet.

Example 7 and Comparative Example 7 A7 alloy was melt-cast using Nd, Pr, Fe, Co metal having a purity of 99.9% by weight and ferroboron in an Ar atmosphere of a high-frequency melting furnace. After casting, the ingot was heated at 1,070 ° C., Ar
The solution was dissolved in an atmosphere for 10 hours and coarsely pulverized to 30 mesh or less. The composition of the obtained alloy was 10.0 Nd-
2.5 Pr-5.0B-1.7 Co-bal. Fe (atomic%). Pr having a purity of 99.9% by weight,
B7 alloy made of CeCo ₄ B type intermetallic compound whose crystal structure is represented by a space group of P6 / mmm in an Ar atmosphere using a Dy, Fe, Co, P, Tb metal and ferroboron as raw materials in a high-frequency melting furnace Was melt-cast and coarsely pulverized in a nitrogen atmosphere to 30 mesh or less. Then 450
At 10 ° C. for 1 hour in nitrogen at 1 atm.
Oxidation treatment was performed at 50 ° C. in the air for 1 hour. The obtained alloy was analyzed and 8.5Pr-8.5Dy-13.2Fe-1
5.0B-2.0P-2.0Tb-2.0N-2.0O
-Bal. A composition of Co was obtained. Next, A7 alloy coarse powder was
9.5% by weight and 10.5% by weight of a B7 alloy coarse powder were weighed and mixed for 30 minutes in a nitrogen-purged V blender.
This mixed coarse powder was finely pulverized with a jet mill using high-pressure nitrogen gas to an average particle size of about 5 μm. While orienting the obtained mixed fine powder in a magnetic field of 15 kOe, about 1 Ton
/ Cm ² under pressure. Next, this compact was sintered at 1,070 ° C. for 1 hour in a sintering furnace in an Ar atmosphere, further subjected to aging heat treatment at 500 ° C. for 1 hour, and quenched to prepare Example 7 magnet alloy M7.

For comparison, an alloy having the same composition as that of Example M7 was produced by a conventional one-alloy method, to thereby obtain Comparative Example E7. That is, one alloy (Comparative Example E7) was initially formed so as to have the same composition as that obtained by mixing and sintering the A7 alloy powder and the B7 alloy powder.
), Weighing, dissolving, pulverizing, sintering, and aging heat treatment, and comparing the magnetic properties with the magnet (Example M7) by the compound powder mixing method. The composition of the magnet alloy M7 was 8. in both Example M7 by the compound powder mixing method and Comparative Example E7 by the one alloy method.
5Nd-3.4Pr-1.2Dy-8.3Co-6.5B-0.3P-0.3Tb-0.3N-0.6O-ba
l.Fe. Note that this composition is a value obtained by analyzing the final sintered body, and the oxygen contained here is oxidized on the surface of the fine powder during the manufacturing process with the oxygen contained as an alloying additive element. It is the sum with the impurities mixed in as described above.
Table 7 shows the values of the magnetic properties and the sintered body densities obtained for both the sintered magnets of Example M7 and Comparative Example E7. Example M7
The magnetic properties of the sintered body are almost the same as those of the comparative example E7, but the residual magnetic flux density, the coercive force and the maximum energy
Example 7 is superior in all values such as the product.
As described above, even if the composition of the magnet alloy is exactly the same, there is a considerable difference in the magnetic properties, indicating that the compound powder mixing method is an extremely effective method for improving the magnetic properties of the Nd magnet.

[0024]

[Table 1]

[0025]

[Table 2]

[0026]

[Table 3]

[0027]

[Table 4]

[0028]

[Table 5]

[0029]

[Table 6]

[0030]

[Table 7]

[0031]

The rare-earth permanent magnet produced according to the present invention has several steps more excellent magnetic properties than conventional rare-earth magnets having the same composition by effectively utilizing expensive additional elements, and has a high coercive force and high coercive force. It has become possible to provide a high-performance magnet with a good balance of residual magnetic flux density and high energy product. Therefore, it is expected that it will be widely used as a high-performance magnet for various electric and electronic devices in the future.

[Brief description of the drawings]

FIG. 1 is a view showing an X-ray analysis pattern of a B1 alloy ingot of Example 1.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takehisa Minowa 2-5-1-5 Kitafu, Takefu-shi, Fukui Shin-Etsu Chemical Co., Ltd. Magnetic Materials Research Laboratory (72) Masanobu Shimao 2-1-1 Kitafu, Takefu-shi, Fukui No. 5 Shin-Etsu Chemical Co., Ltd. Magnetic Materials Research Laboratory (56) References JP-A-3-250607 (JP, A) Journal of the Less-Common Metals, 67 (1979), p. 51-57

Claims (4)

(57) [Claims] 1. An A alloy mainly composed of an R ₂ T ₁₄ B phase, wherein R is at least one or more rare earth elements mainly composed of Nd, Pr, and Dy, and T is at least mainly composed of Fe or Fe and Co. Represents one or more transition metals], and the B alloy is a CeCo ₄ B-type composition formula RFeCoM ¹ M ² whose crystal structure is represented by a space group of P6 / mmm.
[Where R is at least one or more rare earth elements mainly composed of Nd, Pr, and Dy, and M ¹ is Al, Cu, Zn,
In, Si, P, S, Ti, V, Cr, Mn, Ni, G
a, Ge, Zr, Nb, Mo, Pd, Ag, Cd, S
one or two selected from n, Sb, Hf, Ta and W
Seed or more elements, M ² is, B, C, a N, represents one or more elements selected from among O], mp 7
As an alloy mainly composed of an intermetallic compound having a temperature of 50 ° C. or more and 2,000 ° C. or less , 1 to 40% by weight of a B alloy powder is mixed with 99 to 60% by weight of an A alloy powder. A method for producing a rare earth permanent magnet, which comprises performing medium pressure molding, sintering the molded body in a vacuum or an inert gas atmosphere, and further performing heat treatment at a low temperature equal to or lower than a sintering temperature. 2. The composition formula R which is the B alloy according to claim 1.
The intermetallic compound of FeCoM ¹ M ² has a composition formula of R _a Fe _b
Co _c M ¹ _d M ² _e [where the subscripts a, b, c, d, and e are atomic% of each element, and 13 ≦ a ≦ 26, 0 <b ≦ 60, 2
0 ≦ c ≦ 80, 0 ≦ d ≦ 40, and 1 ≦ e ≦ 45]. A method for producing a rare earth permanent magnet. 3. The total of the rare earth elements contained in the mixed powder of the A alloy and the B alloy according to claim 1 or 2 is 10 to 10.
A method for producing a rare earth permanent magnet, wherein the amount is 15 atomic%. 4. The A alloy powder according to claim 1, 2 or 3.
Powder and B alloy powder or a mixture produced by mixing them
The average particle size of the composite powder is 0.2 to 30 μm.
Manufacturing method of rare earth permanent magnets.