JP3151265B2 - 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 of the alloys are a conventionally known R2 Fe14B phase, a rare earth rich phase, and Nd1 + XFe4.
It is B4 phase.

A third method is to use one of the alloys mainly as R2.
A method of manufacturing 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 into an alloy powder composed of an Fe14B 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 the 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 an A alloy is mainly composed of 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 Fe or Fe and
Represents at least one transition metal mainly composed of Co]
Alloy consisting of R, Fe, Co, M ¹ , M ² [this
Here, R is at least one or more mainly composed of Nd, Pr, and Dy.
R ¹ , M ¹ is Al, Cu, Zn, In, Si, P, S,
Ti, V, Cr, Mn, Ni, Ga, Ge, Zr, Nb, Mo, Pd, Ag, C
One or two selected from d, Sn, Sb, Hf, Ta, and W
The above element, M ^2, is selected from among B, C, N, and O
Represents one or more elements]]
Is, CeCo the crystal structure represented by the space group P6 / mmm
Mainly in comprising an alloy of ₄ B-type metal-to-metal compounds, the C alloy
^{R, Fe, Co, M 1} , M 2 [ herein R, M ^1, M ² in the above
The same), and the crystal structure is R bar 3
an alloy composed mainly of PuNi ₃ type metal-to-metal compounds represented by the space group of m, total 1 to 40% by weight mixture of B alloy powder and C alloy powders against A alloy powder 99 to 60 wt% And
The mixed powder is subjected to pressure molding in a magnetic field, the compact is sintered in a vacuum or an inert gas atmosphere, and further heat-treated at a low temperature equal to or lower than the sintering temperature. The average particle size of the B alloy powder and the C alloy powder or a mixed powder produced by mixing them is 0.2 to 30 μm.
m, the melting point of the intermetallic compound mainly contained in the B alloy is 750 ° C or more and 2000 ° C or less, and the crystal structure mainly contained in the B alloy is represented by a space group of P6 / mmm. CeCo ₄ B-type metal-to-metal compound is represented by the composition formula ^{_{R a Fe b Co c M 1}} d M
² _e [The subscripts a, b, c, d, and e indicate the range of atomic%, and 13 ≦ a
≦ 26, 0 ≦ b ≦ 60, 0 <c ≦ 80, 0 ≦ d ≦ 40, 1 ≦ e
≦ 45 in which] in expressed, the main crystal structure included in the _three types of metal-to-metal compounds PuNi represented by space group R bar 3m in C alloy, the composition formula R _f Fe _g Co _h M ¹ _i M ² _j [where subscripts f, g, h,
The range of i, j is atomic%, 16 ≦ f ≦ 34, 0 ≦ g ≦ 60, 0
<H ≦ 80, 0 ≦ i ≦ 40, 0 ≦ j ≦ 10], and the total sum of the rare earth elements contained in the mixed powder of the A alloy and the B alloy is 10 to 15 atomic%. A method for producing a rare earth permanent magnet characterized by the following.

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 A alloy used as a raw material is mainly composed of an R ₂ T ₁₄ B compound phase, and R represents La, Ce, Pr, Nd, Sm, Eu,
Nd, P selected from Gd, Tb, Dy, Ho, Er, Yb and Lu
At least one or 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, the R ₂ T ₁₄ B phase is formed by the peritectic reaction between αFe and the rare earth-rich phase, so that the αFe phase, R-rich phase, B-rich phase, Nd ₃ Co
Equivalents may remain. In the present invention, it is desirable that the amount of the R ₂ Fe ₁₄ B phase in the A alloy is large, so that a solution treatment is performed as necessary. The heat treatment may be performed in a vacuum or Ar atmosphere at a temperature of 700 to 1,200 ° C. for 1 hour or more.

[0012] With respect to 99-60% by weight of the A alloy powder ,
Fe, Co, M ¹ , M ² [where R is mainly Nd, Pr, Dy
At least one or more rare earth elements, M ¹ is Al, Cu,
Zn, In, Si, P, S, Ti, V, Cr, Mn, Ni, Ga, Ge, Z
r, Nb, Mo, Pd, Ag, Cd, Sn, Sb, Hf, Ta, W
One or more selected elements, M ² is B, C,
One or two or more elements selected from N and O
And the crystal structure is P6 / mm
CeCo ₄ B type B alloy powder consisting mainly of gold intermetallic compound represented by the space group of m, and ^{R, Fe, Co, M 1} , M 2 [ wherein
R, M ¹ and M ² are the same as above]]
Is, PuNi ₃ crystal structure is represented by space group R bars 3m
1-40 and C alloy in total composed mainly of the type of metal-to-metal compounds
% By weight, and press-molding the mixed powder in a magnetic field, sintering the formed body in a vacuum or inert gas atmosphere, and further heat-treating at a temperature lower than the sintering temperature. The above crystal structure is P6
/ CeCo ₄ B-type metal-to-metal compounds represented by the space group mmm is Kakiarawasa by a composition formula ^{_{R a Fe b Co c M 1}} d M 2 e, subscripts a, b,
c, d, e are atomic%, 13 ≦ a ≦ 26, 0 ≦ b ≦ 60, 0 <c ≦ 8
0, 0 ≦ d ≦ 40, and 1 ≦ e ≦ 45. a, b, c, d, the range of e is, CeCo ₄ B-type metallic intermetallic compound crystal structure is represented by the space group P6 / mmm within this range is determined from the presence stably If it is out of this range, these intermetallic compounds do not exist and high magnetic properties cannot be obtained. Additional PuNi ₃ type metal-to-metal compounds represented by the space group of the crystal structure R bars 3m is formula R _f Fe _g Co _h
M ¹ _i M ² _j , where the subscripts f, g, h, i, j are in atomic%
Where 16 ≦ f ≦ 34, 0 ≦ g ≦ 60, 0 <h ≦ 80, 0 ≦ i ≦ 40, 0
≦ j ≦ 10. The range of the suffixes f, g, h, i, j is PuNi in which the crystal structure is represented by the space group of R bar 3m.
₃ type metal-to-metal compound has been determined from the presence stable, high magnetic properties can not exist these intermetallic compounds Outside this range can not be obtained. B
The alloy and the C alloy are weighed and melted in a vacuum or 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 heat treatment may be performed in a temperature range of 700 to 1500 ° C. for 1 hour or more in a vacuum or Ar atmosphere.

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
It 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. As a first reason, R, Fe, Co, of M ^1, M ²
Is selected from five elements, CeCo ₄ B-type metal-to-metal compounds represented by the space group of the crystal structure is P6 / mmm, and R, F
e, Co, is selected from five elements M ^1, M ^2, the melting point of PuNi ₃ type metal-to-metal compounds represented by the space group of the crystal structure R bars 3m is, the Nd-based rare earth magnet liquid phase Suitable for sintering
The temperature must be between 750 ° C and 2000 ° C. 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 this method, the viscosity of the Nd-rich phase melt is too low at the sintering temperature due to the presence of the Nd-rich phase having a low melting point, 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 additive alloy is composed of R, Fe, Co, M ¹ and M ² elements.
Are al selected, CeCo ₄ B-type metallic intermetallic compound mainly comprising an alloy crystal structure is represented by the space group P6 / mmm, and
R, Fe, Co, is selected from five elements M ^1, M ^2, by the crystal structure is mainly an alloy containing PuNi ₃ type metal-to-metal compounds represented by the space group of R bars 3m , A alloy can be prevented from containing an Nd-rich phase having a low melting point. 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 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. As elements effective in improving the coercive force of Nd magnets, Pr, Dy,
Tb, Ga, Al, Cu and other elements are known, but they improve the coercive force, but decrease the value of saturation magnetization, which is important for magnet performance, in proportion to the added amount. 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. Grinding is generally coarse grinding,
Although the pulverization is performed stepwise, the 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, Pr, Fe, Co having a purity of 99.9% by weight
Using a metal and ferroboron, an A1 alloy was melt-cast in an Ar atmosphere of a high-frequency melting furnace. After casting, the ingot was solution-solutioned at 1,070 ° C. in an Ar atmosphere for 10 hours. The composition of the obtained alloy is 11.0Nd-1.1Pr-5.9B-2.0Co-bal.Fe.
(Hereinafter, each atomic%, bal. Represents the atomic% of the remaining elements.) Similarly, using Nd, Dy, Fe, Co metal having a purity of 99.9% by weight and ferroboron as raw materials, the crystal structure is composed of a CeCo ₄ B type intermetallic compound represented by a space group of P6 / mmm.
1 Melt and cast the alloy in an Ar atmosphere using a high-frequency melting furnace.
An alloy having the composition 8.4Pr-8.4Dy-15.2Fe-16.7B-bal.Co was obtained.
Similarly, using a high-frequency melting furnace, a C1 alloy made of PuNi ₃ type intermetallic compound whose crystal structure is represented by a space group of R bar 3 m using Pr, Dy, Fe, and Co tal with a purity of 99.9% by weight as raw materials.
Melt casting in Ar atmosphere, composition 12.5Pr-12.5Dy-20.0Fe-b
al.Co alloy was obtained. Each of the ingots of A1, B1, and C1 was coarsely pulverized separately in a nitrogen atmosphere to 30 mesh or less, and then the A1 alloy coarse powder was 88.0% by weight, the B1 alloy was 4.0% by weight, and the C1 alloy was 8.0% by weight. The mixture was weighed and mixed in a nitrogen-purged V blender for 30 minutes. 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 / cm2 while being oriented in a magnetic field of 15 kOe. Next, this compact was placed in a sintering furnace in an Ar atmosphere for 1,
Example 1 Magnet alloy M1 was prepared by sintering at 070 ° C. for 1 hour, aging heat treatment at 530 ° C. for 1 hour, and quenching.

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, and sintering with one alloy (Comparative Example E1) from the beginning so that A1 powder, B1 powder, and C1 powder are mixed and sintered (Example M1) to have the same composition. After aging heat treatment, the magnetic properties were compared with the magnets prepared by the compound powder mixing method. The composition of this magnet alloy is 9.9Nd-2.1Pr-1.1Dy-7.3Co-5.9B-0.4O-bal.Fe in both Example M1 by the compound powder mixing method and Comparative Example E1 by the one 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 ppm. Table 1 shows the values of the magnetic properties and the sintered body densities obtained for both sintered body magnets of Example M1 and Comparative Example E1. The magnetic properties of the example M1 are almost the same as those of the comparative example E1 but the density of the sintered body is almost the same, but the example M1 has a great advantage in all values such as the residual magnetic flux density, the coercive force and the maximum energy product. I have. As described above, even if the compositions of the magnet alloys are 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.

(Examples 2 to 6, Comparative Examples 2 to 6) Purity 99.9
A2-6 alloy was melt-cast using Nd, Pr, Dy, Fe, Co metal and ferroboron by weight in an Ar atmosphere of a high-frequency melting furnace. After casting, the ingot was solution-solutioned at 1,070 ° C. in an Ar atmosphere for 10 hours. The compositions of A2 to A6 in the obtained alloy are shown in Tables 2 to 6. 99.9% by weight
Using Nd, Dy, Fe, Co, ferroboron, various metals, etc. as raw materials, the crystal structure shown in Tables 2 to 6 is P6 / mmm
The CeCo ₄ B-type intermetallic B2 to 6 alloy composed mainly of the compound represented by the space group of the dissolved cast in an Ar atmosphere using a high frequency melting furnace. The composition obtained is also described in the table. Similarly, a PuNi ₃ type intermetallic having a 99.9% by weight Nd, Dy, Fe, Co, various metals, etc. as raw materials and having a crystal structure as shown in Tables 2 to 6 represented by a space group of R bar 3m. A C2-6 alloy mainly composed of a compound was melt-cast in an Ar atmosphere using a high-frequency melting furnace. The composition obtained is also described in the table.
A2-6 alloy, B2-6 alloy and C2-6 alloy 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 each table. The mixture was mixed for 30 minutes in a V blender purged with nitrogen. This mixed coarse powder is jet-milled using high-pressure nitrogen gas,
It was pulverized to an average particle size of about 5 μm. The obtained mixed fine powder
Press molding was performed at a pressure of about 1 Ton / cm2 while orienting in a magnetic field of 15 kOe. Next, this compact was sintered at 1,080 ° C. for 1 hour in a sintering furnace in an Ar atmosphere, and further, 500-580 ° C.
Aging heat treatment at 1 ° C. for 1 hour followed by rapid cooling to produce magnetic alloys M2 to M6 of Examples 2 to 6.

For comparison, alloys having the same composition as in Examples M2 to M6 were produced by the conventional one-alloy method, and Comparative Examples 2 to 6 were designated as magnetic alloys E2 to E6. That is, one alloy (Comparative Examples E2 to 6) was weighed, melted, crushed, and so on so that the same composition as that obtained by mixing and sintering the A2-6 alloy, the B2-6 alloy, and the C2-6 alloy was obtained. After sintering and aging heat treatment, the magnetic properties were compared with the magnets prepared by the compound powder mixing method (Examples M2 to M6). The compositions of the magnet alloys M2 to M6 are as described in Examples M2 to M6 by the compound powder mixing method and Comparative Examples E2 to M6 by the single alloy method.
Both are described in Tables 2 to 6. 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 is an industrial value, about 3,
In both Examples and Comparative Examples, adjustment was made so as to be around 000 to 5,000 ppm by using a glow box or controlling the atmosphere. 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. The magnetic properties of Examples M2 to M6 are almost the same as those of Comparative Examples E2 to E6, but the values of the residual magnetic flux density, coercive force, maximum energy product, etc. of Example E2 are all the same. ~ 6 are the big winners. As described above, even if the compositions of the magnet alloys are 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, Comparative Example 7) 99.9% by weight of purity
An A7 alloy was melt-cast using Nd, Pr, Fe, Co metal and ferroboron in an Ar atmosphere of a high-frequency melting furnace. After casting,
This ingot was solution-solutioned in an Ar atmosphere at 1,070 ° C. for 10 hours and coarsely pulverized to 30 mesh or less. The composition of the obtained alloy was 1.6Nd-10.5Pr-5.9B-1.7Co-bal.Fe (atomic%). 99.9% by weight of Pr, Dy, Fe, Co, P,
CeCo ₄ B whose crystal structure is represented by a space group of P6 / mmm in a high-frequency melting furnace using Tb metal as a raw material in an Ar atmosphere
A B7 alloy made of a mold-type intermetallic compound was melt-cast and coarsely pulverized in a nitrogen atmosphere to 30 mesh or less. Analyze the obtained alloy, 8.4Pr-8.4Dy-15.2Fe-16.7B-2.0P-2.
A composition of 0Tb-bal.Co was obtained. 99.9% by weight of Pr, D
Pu whose crystal structure is represented by R bar 3m type space group in Ar atmosphere using high frequency melting furnace using y, Fe, Co metal as raw materials
Melt casting of C7 alloy composed of Ni ₃ type intermetallic compound,
It was coarsely pulverized in a nitrogen atmosphere to 30 mesh or less. Next, nitriding is performed at 450 ° C and 1 atm of nitrogen for 10 hours.
Oxidation treatment was performed at 250 ° C. for 1 hour in the air. The obtained alloy was analyzed to obtain a composition of 10.0Pr-15.0Dy-20.0Fe-2.0N-2.0O-bal.Co. Next, 87.0% by weight of the A7 alloy coarse powder, 4.0% by weight of the B7 alloy coarse powder, and 8.0% by weight of the C7 alloy were weighed and mixed in a nitrogen blended V blender for 30 minutes. 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. 15 kOe of the obtained mixed fine powder
Press molding at a pressure of about 1 Ton / cm2 while orienting in a magnetic field. Next, this compact was sintered in a sintering furnace in an Ar atmosphere at 1,070 ° C. for 1 hour, 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 obtain Comparative Example E7. That is, weighing, melting, pulverizing, sintering and aging heat treatment of one alloy (Comparative Example E7) from the beginning so as to have the same composition as that obtained by mixing and sintering A7 alloy powder, B7 alloy powder and C7 alloy powder. Then, the magnetic properties were compared with the magnet (Example M7) by the compound powder mixing method. The composition of this magnet alloy M7 is the same as Example M7 by the compound powder mixing method and Comparative Example E by the one alloy method.
7 Both are 1.4Nd-10.4Pr-1.3Dy-6.7Co-5.9B-0.1P-0.1Tb-
0.1N-0.4O-bal.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. The magnetic properties of Example M7 were almost the same as those of Comparative Example E7, but the residual magnetic flux density, coercive force,
Example 6 has a great advantage in all values such as the maximum energy product. As described above, even if the compositions of the magnet alloys are 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 of superior magnetic properties to the conventional rare-earth magnet having the same composition by effectively utilizing expensive additional elements, and has high coercive force and high coercivity. 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.

Continuation of the front page (72) Inventor Kusunoki 2-5-1, Kitafu, Takefu City, Fukui Prefecture Shin-Etsu Chemical Co., Ltd. Magnetic Materials Research Laboratory (72) Inventor Masanobu Shimao 2-5-1 Kitafu, Takefu City, Fukui Prefecture Shin-Etsu Chemical Co., Ltd. Magnetic Materials Research Laboratory (56) Reference JP-A-3-250607 (JP, A)

Claims (6)

(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 one mainly composed of Fe or Fe and Co. Represents one or more transition metals], and B
The alloys are R, Fe, Co, M ¹ , M ² [where R is Nd, Pr, Dy
At least one or more kinds of rare earth elements as a main component, M ¹
Means Al, Cu, Zn, In, Si, P, S, Ti, V, Cr, Mn, N
i, Ga, Ge, Zr, Nb, Mo, Pd, Ag, Cd, Sn, Sb, Hf, T
a, one or more elements selected from W, M ²
Is one or more selected from among B, C, N and O
And an alloy consisting of CeCo ₄ B type intermetallic compound whose crystal structure is mainly represented by a space group of P6 / mmm, and C alloy is R, Fe, Co ,
5 types of M ¹ and M ² [where R, M ¹ and M ² are the same as above]
Is selected from the elements, primarily as alloys the crystal structure consists PuNi ₃ type metal-to-metal compounds represented by the space group of R bars 3m, B alloy powder and C relative to A alloy powder 99 to 60 wt% The alloy powder is mixed in a total of 1 to 40% by weight, the mixed powder is compacted in a magnetic field, the compact is sintered in a vacuum or an inert gas atmosphere, and further heat-treated at a low temperature below the sintering temperature. A method for producing a rare earth permanent magnet, comprising: 2. The CeCo ₄ B crystal structure mainly contained in the B alloy according to claim 1 represented by a space group of P6 / mmm.
Gold intermetallic compound of the type is represented by the composition formula ^{_{R a Fe b Co c M 1}} d M 2 e [ here subscripts a, b, c, d, e in atom% of each element, 13 ≦ a ≦ 26,0
≤ b ≤ 60, 0 <c ≤ 80, 0 ≤ d ≤ 40, and 1 ≤ e ≤ 45]. _3. A PuNi ₃ type crystal structure mainly contained in the C alloy according to claim 1 represented by a space group of R bar 3m .
Gold intermetallic compound, composition formula ^{_{R f Fe g Co h M 1}} i M 2 j [ where subscript f, g, h, i, j in atomic%, 16 ≦ f ≦ 34,0 ≦ g ≦ 60, 0 <
h ≦ 80, 0 ≦ i ≦ 40, and 0 ≦ j ≦ 10]. 4. The total of the rare earth elements contained in the mixed powder of the A alloy and the B alloy according to claim 1 is 10 to 15 atomic%.
A method for producing a rare earth permanent magnet. 5. B according to claim 1, 2, 3, or 4
The crystal structure mainly contained in the alloy is represented by a space group of P6 / mmm, CeCo ₄ B type intermetallic compound, and the crystal structure mainly contained in the C alloy is represented by a space group of R bar 3m. Melting point of PuNi ₃ type intermetallic compound is 750 ℃ or more and 2000 ℃
A method for producing a rare earth permanent magnet, characterized in that: 6. An A alloy powder, a B alloy powder and a C alloy powder according to claim 1, 2, 3, 4 or 5, or an average particle diameter of a mixed powder produced by mixing them.
A method for producing a rare earth permanent magnet, characterized in that the thickness is 30 μm.