JP3126199B2 - 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].

[0004] 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 having different kinds and contents of rare earth elements are used. Method of producing and mixing and sintering [JP-A-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 these methods, the phase contained in each alloy is a conventionally known R ₂ Fe ₁₄ B phase, a rare earth-rich phase, Nd ₁ + XFe ₄
B ₄ phase.

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 manufacturing method by the mixing method that are not suitable or sufficient for realizing 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 about 9 kOe at most, and there is a defect peculiar to the Nd magnet that the coercive force decreases with increasing temperature, which is not practically sufficient. Magnet properties.
Further, the production by the liquid quenching method is not an industrial method because the cost is too high.

In the second method, the phases coexisting with the two types of raw material alloy powder are an R ₂ Fe ₁₄ B compound and Nd ₁ + XFe ₄
B ₄ phase. These phases are basically the same as the phases existing in the production method using one ordinary 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 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 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 is melted from, for example, around 600 ° C., the viscosity of the low-melting phase becomes very small at an actual sintering temperature of 1,100 ° C. 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. Also, like 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 characteristics are deteriorated.
As described above, in the mixing method according to the prior 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 provide a method for producing a rare-earth permanent magnet excellent in balanced magnetic properties by improving the drawbacks of the conventional method for producing an Nd magnet by a mixing method.

[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 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 alloy A is mainly composed of 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 and Co)
Transition metal and an alloy consisting of a representative) that, A alloy powder 99
Crystal structure of CaZn ₅ type, CeCo ₄ B
Type, Ce ₃ Co ₁₁ B ₄ type, Ce ₂ Co ₇ B ₃ type, CeCo ₃ B ₂ type, Y
CrB ₄ type, Ce ₃ Co ₁₁ B ₂ type, ThCr ₂ Si ₂ type, Th ₆ Mn ₂₃ type,
Pr ₅ Co ₁₉ type, Ce ₂ Ni ₇ type, Ce ₂ Co ₅ B ₂ type, PuNi ₃ type, MgCu ₂
And at least one or more intermetallic compound powders selected from the group of Co-containing intermetallic compounds represented by the CeCoB type are mixed in an amount of 1 to 40% by weight, and the mixed powder is subjected to pressure molding in a magnetic field. the molded article was sintered in a vacuum or in an inert gas atmosphere, and then a method for preparing a rare earth permanent magnet, characterized in that the heat treatment at low temperatures below the sintering temperature, more particularly ₅ type crystal structure is CaZn , CeCo ₄ B type, Ce ₃ Co ₁₁ B ₄
Type, Ce ₂ Co ₇ B ₃ type, CeCo ₃ B ₂ type, YCrB ₄ type, Ce ₃ Co
₁₁ B ₂ type, ThCr ₂ Si ₂ type, Pr ₅ Co ₁₉ type, Ce ₂ Ni ₇ type, Ce ₂ Co
₅ B ₂ type, PuNi ₃ type, MgCu ₂ type and CeCoB type composition of the intermetallic compounds in composition formula is ^{_{R a Fe b Co c M 1}} d M 2 e [ herein R is, Nd, Pr, and Dy At least one or more rare earth elements as main components, M ¹ is Al, Cu, Zn, In, Si, P, S, Ti,
V, Cr, Mn, Ni, Ge, Zr, Nb, Mo, Pd, Ag, Cd, Sn, S
b, Hf, Ta, 1 or two or more elements selected from among W, M ² represents B, C, N, one or two or more elements selected from among O, subscripts a, b, c, d and e are atomic% of each element, 13 ≦ a ≦ 41, 0 ≦ b ≦ 60, 0 <c ≦ 85, 0 ≦ d ≦
40, representing the range of 0 ≦ e ≦ 70],
The intermetallic compound having a crystal structure of Th ₆ Mn ₂₃ type has a composition formula of _Ra Fe _{b
^{Co f M 1 d M 2 e}} [ herein R, M ^1, M ² and a, b, d, e are as defined above, f is representative of the range of 0 <f ≦ 60 in atomic%] represented by Wherein the total of the rare earth elements contained in the mixed powder of the alloy A and each intermetallic compound is 10 to 15% by atomic%.
Wherein the average particle diameter of the A alloy powder, the powder of each intermetallic compound, and the mixed powder obtained by mixing them is 0.2 to 30 μm, and the melting point of each intermetallic compound is 750 to 2,000 ° C. To manufacture a rare earth permanent magnet.

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 intermetallic compound powders having different compositions and crystal structures are mixed and sintered. (Less than,
It is called compound powder mixing method. ) One A alloy as a raw material mainly consists of an R ₂ T ₁₄ B compound phase. R is La including Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb
And at least one or more rare earth elements mainly composed of Nd, Pr, and Dy selected from Lu. T is Fe
And a transition metal mainly composed of Co, and the content of Co is 0
-40% by weight (not including 0) . 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 T ₁₄ B phase is formed by the peritectic reaction between αFe and the rare earth-rich phase, the αFe phase, R-rich phase, B-rich phase, Nd ₃ Co phase, etc. are solidified and segregated even after casting. 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 conditions are vacuum or Ar atmosphere,
The heat treatment may be performed in a temperature range of 700 to 1200 ° C. for 1 hour or more.

The intermetallic compound as another raw material has a crystal structure of CaZn ₅ type, CeCo ₄ B type, Ce ₃ Co ₁₁ B ₄ type,
Ce ₂ Co ₇ B ₃ type, CeCo ₃ B ₂ type, YCrB ₄ type, Ce ₃ Co ₁₁ B
Type ₂ , ThCr ₂ Si type ₂ , Th ₆ Mn ₂₃ Type, Pr ₅ Co ₁₉ type, Ce ₂ Ni
₇ type, Ce ₂ Co ₅ B ₂ type, PuNi ₃ type, MgCu ₂ type, CeCoB type, containing at least one or two or more metals selected from these intermetallic compounds 1 to 40% by weight of compound powder to 99 to 60% by weight of A alloy
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 amount of intermetallic compound is 1
If it is less than 40% by weight, the sintering density does not increase and coercive force cannot be obtained. If it exceeds 40% by weight, the ratio of the non-magnetic phase after sintering becomes too large, the residual magnetic flux density decreases, and high magnetic properties are obtained. Can not be.

[0013] Among the above various intermetallic compounds, other intermetallic compounds, except for the Th ₆ Mn ₂₃ type intermetallic compound, its composition is represented by a composition formula ^{_{R a Fe b Co c M 1}} d M 2 e , Where R is N
d, Pr, at least one or more rare earth elements mainly containing Dy, M ¹ is Al, Cu, Zn, In, Si, P, S, Ti, V, Cr,
Mn, Ni, Ge, Zr, Nb, Mo, Pd, Ag, Cd, Sn, Sb, Hf, T
a, one or more elements selected from W, M ²
Represents one or more elements selected from B, C, N, and O, and the subscripts a, b, c, d, and e are 13% by atom% of each element.
≦ a ≦ 41, 0 ≦ b ≦ 60, 0 <c ≦ 85, 0 ≦ d ≦ 40, 0 ≦
e ≦ 70. The ranges of a, b, c, d, and e are determined from the fact that the above-mentioned various intermetallic compounds are stably present within this range. It no longer exists and high magnetic properties cannot be obtained.

[0014] intermetallic compound crystal structure Th ₆ Mn ₂₃ type, the composition formula ^{_{R a Fe b Co f M 1}} d M 2 e [ herein R, M ^1, M ² and
a, b, d, and e are the same as above, and f represents the range of 0 <f ≦ 60 in atomic%]. The range of a, b, d, e, f is
It is determined from the fact that the above-mentioned various intermetallic compounds are stably present within this range, and if it is outside this range, these intermetallic compounds will not be present and high magnetic properties cannot be obtained.

Each of these intermetallic compounds is weighed and melted in a vacuum or inert gas, preferably an Ar atmosphere, and cast. As raw material metals, pure rare earth elements or rare earth alloys, pure iron, ferroboron, various pure metals, and alloys thereof are used. However, trace impurities inevitably contained in general industrial production are included. If there is solidification segregation, the obtained ingot is subjected to a solution treatment if necessary. The condition is 700 ~ under vacuum or Ar atmosphere.
The heat treatment may be performed in a temperature range of 1,500 ° C. for one hour or more.

Each of the above-mentioned intermetallic compounds can be produced by heat-treating a ribbon having a predetermined composition obtained by the liquid quenching method. That is, in the liquid quenching method, the alloy after quenching is amorphous or microcrystalline, but when this is heated at a temperature higher than the crystallization temperature for a certain period of time, the quenched alloy crystallizes or recrystallizes and grows. As a result, the above-mentioned 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 Further, the composition of the alloy powder to be mixed is made extremely limited, and one or two or more kinds of intermetallic compounds selected from the above-mentioned intermetallic compounds are simultaneously coexisted in one alloy so that R ₂ Fe ₁₄ The production method of mixing with the B phase, or coexisting the R ₂ Fe ₁₄ B phase with one or more intermetallic compounds, and further mixing this with R ₂ Fe ₁₄ B is also applicable to the metal constituting the mixed powder. If the type of the intermetallic phase is the same as that according to the invention, it can be regarded as the same as the method according to the invention.

As described above, since the raw materials used in the present invention use the materials used in ordinary industrial production, they contain inevitable impurity elements in industrial production. For example, element C, which is the most representative industrial impurity, is contained in any of the alloys of the present invention in the range of 0.01 to 0.3% by weight. The method for manufacturing a magnet according to the present invention includes:
The powder metallurgy method using fine powder is the basic manufacturing method.
Therefore, although atmosphere control such as gas replacement is performed in each process, it is difficult to completely prevent material oxidation due to increase in powder surface area and activation of the surface. Typically, it contains 0.05-0.6% by weight of oxygen.

In the present invention, as described above, one or more of the intermetallic compound powders are mixed with the A alloy powder at a predetermined ratio to obtain high magnetic properties. Hereinafter, the reason why the compound powder mixing method of the present invention provided high magnetic properties will be described. First, the crystal structure is CaZn ₅ type, CeCo ₄ B type, Ce ₃ Co ₁₁ B
₄ type, Ce ₂ Co ₇ B ₃ type, CeCo ₃ B ₂ type, YCrB type _4, Ce ₃ Co
₁₁ B ₂ type, ThCr ₂ Si ₂ type, Th ₆ Mn ₂₃ Type, Pr ₅ Co ₁₉ type, Ce ₂
The melting point of each intermetallic compound phase containing Co represented by Ni ₇ type, Ce ₂ Co ₅ B ₂ type, PuNi ₃ type, MgCu ₂ type, and CeCoB type is Nd
Suitable for liquid phase sintering of rare earth magnets
° C or lower. 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, by appropriately selecting the type of each intermetallic compound phase, it is possible to prevent the Nd-rich phase having a low melting point from being contained in the mixed powder with the A alloy. Therefore, the influence of the atmosphere in the sintering step is reduced, and high magnetic properties can be obtained.

The second reason is that the corrosion resistance is improved by adding Co. Since alloys and compounds added in the mixing method generally contain more rare earth elements than the base alloy, they are easily oxidized and deteriorated 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 rich in rare earth elements, and as a result, the oxidative deterioration of the fine powder during the sintering process is reduced. As a result, excellent magnetic characteristics can be stably obtained.

The third reason is that various alloying 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, Tb, Ga, Al, C are effective elements for improving the coercive force of Nd magnets.
Although u and other elements are known, they improve the coercive force, but decrease the value of the saturation magnetization, which is important for magnet performance, in proportion to the amount of addition. R is a ferromagnetic phase
_{When a} large amount of these elements is contained in the ₂ Fe ₁₄ B 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,
Each intermetallic compound mixed with the A alloy melts by itself or reacts and melts with the A alloy near the sintering temperature, and further diffuses to form an R ₂ Fe ₁₄ B phase and an Nd-rich phase. . This reaction produces a liquid phase near the grain boundaries,
Liquid phase sintering proceeds by the liquid phase, but Pr, Dy, Tb, Ga, Al, Cu and various elements M ¹ ,
M ² would after sintering also abundant in the vicinity of grain boundaries.
Accordingly, 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 each intermetallic compound obtained as described above are obtained by crushing each ingot,
It is mixed in 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 each intermetallic compound have substantially 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, sinterability deteriorates and high magnetic properties are obtained. Disappears.

A alloy powder, crystal structure of CaZn ₅ type, CeCo
₄ B type, Ce ₃ Co ₁₁ B ₄ type, Ce ₂ Co ₇ B ₃ type, CeCo ₃ B ₂
Type, YCrB ₄ type, Ce ₃ Co ₁₁ B ₂ type, ThCr ₂ Si ₂ type, Th ₆ Mn
_{twenty three} Type, Pr ₅ Co ₁₉ type, Ce ₂ Ni ₇ type, Ce ₂ Co ₅ B ₂ type, PuNi ₃
The mixing ratio of at least one or two or more alloy powders selected from Co-containing various intermetallic compound phases represented by the Al, MgCu ₂ and CeCoB types is 1 to 99 to 60% by weight of the A alloy powder. If the amount of each intermetallic compound powder is less than 1% by weight, the coercive force cannot be obtained because the sinterability is deteriorated and the sintered density does not increase.
If the amount exceeds 10% by weight, the ratio of the non-magnetic phase after sintering becomes too large, and the residual magnetic flux density decreases, so that high magnetic properties cannot be obtained. The obtained mixed fine powder is then molded 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 true density ratio, and it is possible to obtain an excellent rare earth magnet with high residual magnetic flux density, large coercive force and good squareness .

[0023]

EXAMPLES Hereinafter, specific embodiments of the present invention will be described with reference to Examples.
However, the present invention is not limited to these.
There is no. (Example 1, Comparative Example 1) Nd, Pr, Fe, Co having a purity of 99.9% by weight
Ar atmosphere in high-frequency melting furnace using metal and ferroboron
In the A1 alloy (hereinafter A1 and A2 depending on the composition of the A alloy)
...) was melt-cast. After casting, this ingot
The solution was solution-treated in an Ar atmosphere at 1,070 ° C. for 10 hours. Get
The composition of the alloy was 10.0Nd-2.0Pr-6.3B-1.0Co-80.7Fe
(Atomic%). 99.9% by weight of Pr, Dy,
Mg, Fe, Co, Ga metal _Two Type intermetallic compound
Melting and casting in an Ar atmosphere using a high-frequency melting furnace, composition 16.7
An alloy of Pr-16.7Dy-15.2Fe-4.0Ga-47.4Co was obtained. A1,
MgCu_Two Each ingot of type intermetallic compound separately
Coarsely pulverize in a nitrogen atmosphere to 30 mesh or less, then
93.0% by weight of A1 alloy coarse powder, MgCu_Two Type intermetallic compound
 7.0% by weight and weighed in a nitrogen-blended V blender.
Mix for minutes. This mixed coarse powder is mixed with high pressure nitrogen gas.
It was pulverized to a mean particle size of about 5 μm by a wet mill. Get
While orienting the mixed fine powder in a magnetic field of 15 kOe,
1 Ton / cm^Two Press molding. Then this molding
The body was sintered at 1,070 ° C for 1 hour in a sintering furnace with Ar atmosphere.
Further, after aging heat treatment at 530 ° C for 1 hour, the mixture was quenched.
A stone alloy M1 was produced.

For comparison, an alloy having the same composition as that of Example M1 was produced by a conventional one-alloy method, and Comparative Example 1 was used as a magnet alloy E1.
And That is, weighing, melting, pulverizing, and sintering of one alloy (Comparative Example E1) from the beginning so that A1 and MgCu ₂ type intermetallic compound 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 was 9.5Nd-2.7Pr-0.9Dy-3.4Co-6.0B-0.2Ga-0.4O in both Example M1 by the compound powder mixing method and Comparative Example E1 by the one alloy method.
-76.9Fe. 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 was about an industrial value of about 4,000 ppm. Table 1
(Hereinafter, bal. In the table represents atomic% of the balance of the elements.) The values of the magnetic properties and the sintered body densities obtained for the sintered magnets of Example M1 and Comparative Example E1 are shown. 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. However, the example M1 is far superior in all the 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.

[0025]

[Table 1]

(Example 2, Comparative Example 2) 99.9% by weight of purity
An A2 alloy was melt-cast using Nd, Pr, Fe, Co metal and ferroboron 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-1.0Pr-5.9B-2.
0Co-80.1Fe (atomic%). Similarly, using Nd, Dy, Fe, Co, V metal and ferroboron having a purity of 99.9% by weight as raw materials, a CaZn _5- type intermetallic compound is melt-cast in an Ar atmosphere using a high-frequency melting furnace, and the composition is 8.4Nd-8.4Dy-15.2. Fe-2.0V-66.
An alloy of 0Co was obtained. 99.9% by weight of Pr, Dy, Co, N
Using i metal as a raw material, CeCoB type intermetallic compound was melt-cast in an Ar atmosphere using a high-frequency melting furnace, and the composition was 16.7 Pr-16.
An alloy of 7Dy-33.3B-4.0Ni-29.3Co was obtained. A2, CaZn5
Type intermetallic compound, and less coarse pulverized to 30 mesh in each ingot each separately in a nitrogen atmosphere CeCoB type intermetallic compound, then the A2 alloy coarse powder 86.0 wt%, the CaZn ₅ type intermetallic compound 11.0 % By weight of CeCoB type intermetallic compound.
0% by weight 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. While orienting the obtained mixed fine powder in a magnetic field of 15 kOe, about 1
Press molding was performed under a pressure of Ton / cm ² . Then, the compact was sintered in a sintering furnace in an Ar atmosphere at 1,070 ° C. for 1 hour, and further subjected to aging heat treatment at 530 ° C. for 1 hour and quenched to prepare Example 2 magnetic alloy M2.

For comparison, an alloy having the same composition as that of Example M2 was produced by a conventional one-alloy method, and Comparative Example 2 was prepared using a magnet alloy E2.
And That, A2 and CaZn ₅ intermetallic compound and CeCoB type intermetallic compound and a mixture of sintered (Example M2) by the same composition as the way one alloy from the beginning (Comparative Example E2
), Weighed, melted, crushed, sintered and aged heat treatment, and compared the magnetic properties with the magnet by the compound powder mixing method. The composition of this magnet alloy was determined in Example M2 by the compound powder mixing method,
Comparative Example E2 by 1 alloy method Both 10.5Nd-1.3Pr-1.3Dy-
8.9Co-6.1B-0.2V-0.1Ni-0.4O-71.2Fe. 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 was about an industrial value of about 4,000 ppm. Table 2 shows Example M2 and Comparative Example E2.
2 shows the values of the magnetic properties and the sintered body densities obtained for both sintered body magnets. The magnetic properties of Example M2 were almost the same as those of Comparative Example E2, but the density of the sintered body was almost the same. However, Example M2 was significantly superior in all values such as residual magnetic flux density, coercive force and 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 3 to 6, Comparative Examples 3 to 6) Purity 99.9
Various A alloys were melted and cast in a high-frequency melting furnace in an Ar atmosphere using Nd, Pr, Dy, Fe, Co metal, etc. in weight% and ferroboron. After casting, the ingot was solution-solutioned at 1,070 ° C. in an Ar atmosphere for 10 hours. A3 to A6 of the obtained A alloy
Are shown in Tables 3-6. 99.9% by weight
Using Nd, Dy, Fe, Co, various metals and ferroboron as raw materials, each intermetallic compound as shown in Tables 3 to 6 was melt-cast in an Ar atmosphere using a high-frequency melting furnace. The obtained compositions are also described in Tables 3 to 6. A and various intermetallic compounds are separately coarsely pulverized in a nitrogen atmosphere to 30 mesh or less, and then A and various intermetallic compounds are mixed as described in the column of mixed weight in the table, and replaced with nitrogen. Mix for 30 minutes in a 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, this compact was sintered at 1,080 ° C. for 1 hour in a sintering furnace in an Ar atmosphere, and then subjected to aging heat treatment at 540 ° C. for 1 hour and rapidly cooled to produce magnetic alloys M3 to M6 of Examples 3 to 6.

For comparison, alloys having the same composition as in Examples M3 to M6 were produced by a conventional one-alloy method, and Comparative Examples 3 to 6 were designated as magnetic alloys E3 to E6. That is, weighing, melting, pulverizing, sintering, and aging heat treatment of one alloy (Comparative Examples E3 to E6) from the beginning so as to have the same composition as that obtained by mixing and sintering the A alloy and each intermetallic compound. The magnetic properties were compared with magnets prepared by the compound powder mixing method (Examples M3 to M6). The compositions, magnetic properties and sintered body densities of Examples M3 to M6 by the compound powder mixing method and Comparative Examples E3 to E6 by the one alloy method are also shown in Tables 3 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 3,000 to 5,000 ppm
In each of Examples and Comparative Examples, adjustment was made by using a glow box or controlling the atmosphere so as to be near. As is clear from the table, the magnetic properties of Examples M3 to M6 are almost the same as those of Comparative Examples E3 to E6, but the residual magnetic flux density, coercive force, maximum energy product, etc.
Examples M3 to M6 greatly outperform at all values.
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
A7 alloy was melt-cast using 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 and coarsely pulverized to 30 mesh or less. The composition of the obtained alloy is 2.0Nd-9.5Pr-0.5Dy-6.0B-9.9Co-72.1F
e (atomic%). 99.9% by weight Nd, D
Using y, Fe, Co, Zn metal as raw materials, Ar
The CaZn type ₅ intermetallic compound was melted and cast in an atmosphere, and coarsely pulverized in a nitrogen atmosphere to 30 mesh or less. Then 450
At 10 ° C., nitriding was performed in nitrogen at 1 atm for 10 hours. Analyze the obtained alloy, 8.4Nd-8.4Dy-13.3Fe-6.0Zn-6.0N-57.9C
o was obtained. 99.9% by weight of Pr, Dy, Fe, Co,
Using Ge metal as a raw material, a Ce ₃ Co ₁₁ B ₂ type intermetallic compound was melt-cast in an Ar atmosphere using a high-frequency melting furnace, and coarsely pulverized in a nitrogen atmosphere to 30 mesh or less. Then 450
Nitriding in nitrogen at 1 ° C for 10 hours
Oxidation treatment was performed in air at ℃ for 1 hour. The obtained alloy was analyzed and 5.3Pr-13.6Dy-8.4Fe-12.5 B-2.0Ge-4.0N-4.0O
A composition of -50.2Co was obtained. 99.9% by weight of Pr, Dy,
Using Fe, Co, and Sn metals as raw materials, a PuNi ₃ intermetallic compound was melt-cast in an Ar atmosphere using a high-frequency melting furnace, and coarsely pulverized in a nitrogen atmosphere to 30 mesh or less. The obtained alloy was analyzed to obtain a composition of 12.5Pr-12.5Dy-20.0Fe-2.0Sn-53.0Co. Next, 88.0% by weight of A6 alloy coarse powder, 3.0% by weight of CaZn type ₅ intermetallic compound powder, 5.0% by weight of Ce ₃ Co ₁₁ B ₂ type intermetallic compound powder, and 4.95% by weight of PuNi _{3 type} intermetallic compound powder.
0% by weight 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 / cm ² while being oriented in a magnetic field of 15 kOe. Next, the compact was sintered at 1,070 ° C. for 1 hour in a sintering furnace in an Ar atmosphere.
Further aging heat treatment at 500 ° C. for 1 hour followed by rapid cooling.
A magnet alloy M7 was produced.

For comparison, an alloy having the same composition as that of Example M7 was produced by a conventional one-alloy method, and Comparative Example 7 was used for magnet alloy E7.
And That is, A7 powder, CaZn type ₅ intermetallic compound powder,
From the beginning, one alloy (Comparative Example E7) was weighed, melted, crushed, and mixed with Ce ₃ Co ₁₁ B ₂ type intermetallic compound powder and PuNi ₃ intermetallic compound powder to obtain the same composition as that obtained by mixing and sintering. After sintering and aging heat treatment, the magnetic properties were compared with the magnet (Example M7) by the alloy powder mixing method. The composition of the magnetic alloy M7 was 2.0Nd-9.1Pr-1.7Dy-14.5Co-6.0B- in both Example M7 by the compound powder mixing method and Comparative Example E7 by the one alloy method.
0.2Zn-0.4N-0.1Ge-0.1Sn-0.6O-65.3Fe. 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 Example M7.
The values of the magnetic characteristics and the sintered body densities obtained for both sintered body magnets of Comparative Example E7 and Comparative Example E7 are shown. Although the magnetic properties of Example M7 are almost the same as those of Comparative Example E7, the density of the sintered body is almost the same, but Example M7 is far superior in all values such as residual magnetic flux density, coercive force and 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 alloy powder mixing method is an extremely effective method for improving the magnetic properties of the Nd magnet.

[0032]

[Table 2]

[0033]

[Table 3]

[0034]

[Table 4]

[0035]

[Table 5]

[0036]

[Table 6]

[0037]

[Table 7]

[0038]

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 is possible to provide a high-performance magnet with a balance of residual magnetic flux density and high energy product,
It is expected to be widely used as high-performance magnets for various electric and electronic devices.

Continued on the front page (72) Inventor Masao Yoshikawa 2-5-1, Kitafu, Takefu-shi, Fukui Shin-Etsu Chemical Industry Co., Ltd. Magnetic Materials Research Laboratories (72) Masanobu Shimao 2-5-1, Kitafu, Takefu-shi, Fukui Shin-Etsu (56) References JP-A-1-118443 (JP, A) JP-A-63-197305 (JP, A) JP-A-3-250607 (JP, A)

Claims (6)

(57) [Claims] An alloy A is mainly composed of an R ₂ T ₁₄ B phase (here, R
Is an alloy comprising at least one or more rare earth elements mainly composed of Nd, Pr, and Dy, and T represents a transition metal mainly composed of Fe and Co ). Crystal structure is CaZn ₅ type, CeCo ₄ B type, Ce ₃ Co ₁₁ B ₄ type, Ce ₂ Co ₇
B ₃ type, CeCo ₃ B ₂ type, YCrB ₄ type, Ce ₃ Co ₁₁ B ₂ type,
ThCr ₂ Si ₂ type, Th ₆ Mn ₂₃ type, Pr ₅ Co ₁₉ type, Ce ₂ Ni ₇ type, Ce ₂ C
o ₅ B ₂ type, PuNi ₃ type, MgCu ₂ type and at least one or more intermetallic compound powder is selected from intermetallic compounds containing Co represented by CeCoB type 1 to 40 wt% Mixing, pressing the mixed powder in a magnetic field under pressure, sintering the formed body in a vacuum or an inert gas atmosphere, and then performing heat treatment at a low temperature not higher than the sintering temperature. Method. 2. The crystal structure according to claim 1, wherein the crystal structure is CaZn ₅ type, Ce
Co ₄ B type, Ce ₃ Co ₁₁ B ₄ type, Ce ₂ Co ₇ B ₃ type, CeCo ₃ B ₂
Type, YCrB ₄ type, Ce ₃ Co ₁₁ B ₂ type, ThCr ₂ Si ₂ type, Pr ₅ Co
The composition of the group of intermetallic compounds of type ₁₉ , Ce ₂ Ni ₇ type, Ce ₂ Co ₅ B ₂ type, PuNi ₃ type, MgCu ₂ type and CeCoB type is represented by the composition formula R
^{_{a Fe b Co c M 1 d}} M 2 e [ wherein R is, Nd, Pr, at least one or more rare earth elements mainly containing Dy, M ¹ is Al, Cu, Z
n, In, Si, P, S, Ti, V, Cr, Mn, Ni, Ge, Zr, N
b, Mo, Pd, Ag, Cd, Sn, Sb, Hf, Ta, 1 or two or more elements selected from among W, M ² is B, C, N, O
Represents one or two or more elements selected from the following, and the subscripts a, b, c, d, and e are atomic% of each element, 13 ≦ a ≦ 41, 0 ≦ b ≦
60, 0 <c ≦ 85, 0 ≦ d ≦ 40, and 0 ≦ e ≦ 70]. Wherein the intermetallic compound crystal structure of Th ₆ Mn ₂₃ type according to claim 1, the composition formula ^{_{R a Fe b Co f M 1}} d M 2 e [ herein R, M ^1, M ² and a, b, d, and e are the same as above, and f represents an atomic% in the range of 0 <f ≦ 60]. 4. A method for producing a rare earth permanent magnet, wherein the total of the rare earth elements contained in the mixed powder of the alloy A and each intermetallic compound according to claim 1 is 10 to 15 atomic%. 5. The powder of the A alloy, the powder of each intermetallic compound, and the mixed powder obtained by mixing them, according to claim 1, 2, 3 or 4, has an average particle size of 0.2 to 30 μm. Method for manufacturing rare earth magnets. 6. A method for producing a rare earth permanent magnet, wherein the melting point of each intermetallic compound according to claim 1, 2, 3, 4 or 5 is 750 to 2,000 ° C.