JPH11283815A - Magnetic material and bonded magnet using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the quantity of rare earth elements, without damaging magnetic characteristic in a magnetic material, consisting of a magnetic material of an R-Fe-N system, a TbCu7 type compound and its nitrides. SOLUTION: A magnetic material is provided with a constitution which is substantially expressed by a general expression: (R<1> XR<2> YBZ M1- X- Y- Z)1- QNQ (In the expression, R<1> shows at least one kind of element selected from among rare earth elements, R<2> shows at least one kind of element selected from among Zr, Hf and Sc, M shows at least one kind of element selected from among Fe and Co, and X, Y, Z and Q are numbers respectively satisfying 0.02<=X<=0.07, 0.001<=Y, 0.03<=X+Y<=0.2, 0<=Z<=0.1, 0.001<=Q<=0.2) and the main phase of the material is a crystalline phase with a TbCu7 type crystal structure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a magnet material used as a high-performance permanent magnet and a bonded magnet using the same.

[0002]

2. Description of the Related Art Sm-Co based magnets, Nd-Fe-B based magnets and the like are conventionally known as a kind of high performance rare earth permanent magnets. These magnets contain a large amount of Fe or Co and contribute to an increase in the saturation magnetic flux density. Further, these magnets contain rare earth elements such as Nd and Sm, and the rare earth elements bring about very large magnetic anisotropy due to the behavior of 4f electrons in the crystal field. Thereby, the coercive force is increased, and a high-performance magnet is realized.

[0003] Such high-performance magnets are mainly used for electric equipment such as motors and measuring instruments. In recent years, the demand for miniaturization and price reduction of various electric devices has increased,
In order to respond to the demand, higher performance permanent magnets are required. In response to such demands, R-Fe-N magnets have attracted attention as magnet materials having such a possibility (Japanese Patent Publication No. 5-82041, Japanese Patent Application Laid-Open No. 2-57663, 4-288801). Further, the present inventors have proposed a TbCu ₇ type compound and a nitride thereof having excellent magnet properties such as high remanent magnetization (Japanese Patent Application Laid-Open No. 6-129936).
No. 9-74006, etc.).

[0004]

The above-mentioned R-Fe-N
Magnet materials and magnet materials made of TbCu ₇ type compound and its nitride are expected to have higher performance as magnet materials, but Sm-Co magnets and Nd-Fe-B
Like a system magnet, it contains a relatively large amount of expensive rare earth elements, and a reduction in the content of rare earth elements is required for further cost reduction and resource saving.

In particular, when the main component of the rare earth element is Sm, Sm tends to volatilize during melting due to its high vapor pressure, making it difficult to control the composition. This Sm
Variations in the amount lead to variations in magnetic properties, especially coercivity.

[0006] Accordingly, it is possible to reduce the amount of expensive rare earth elements without impairing the magnetic characteristics of the R-Fe-N based magnet material or the magnet material composed of TbCu ₇ type compound and its nitride. Is desired.

SUMMARY OF THE INVENTION The present invention has been made to address such problems, and provides a magnet material capable of reducing the amount of rare earth elements without deteriorating magnetic properties, and a bonded magnet using the same. It is intended to be.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above-mentioned object, and as a result, have obtained the following findings, and have made the present invention based on such findings. Reached.

That is, R-Zr-Fe ternary system, RZ
In the r-Fe-Co quaternary system, the presence of Zr causes a crystalline phase having a high concentration of Fe or Co (for example, TbCu ₇
Phase having a type crystal structure (hereinafter referred to as TbCu ₇ phase))
Is generated. For example, it has been found that in the TbCu ₇ phase, Zr mainly occupies rare earth sites. For this reason, there is a possibility that the content of the rare earth element can be reduced without increasing the content of the rare earth site by increasing the content of Zr.

From the viewpoint of reducing the cost and saving resources of the magnet material based on the reduction of the content of the rare earth element, the present inventors considered that Zr relative to the total amount of the rare earth element and the element occupying the rare earth site represented by Zr. As a result of studying an increase in the ratio of such elements, it was found that excellent magnetic properties were exhibited even in a composition containing a small amount of a rare earth element.

[0011] The present invention has been made based on these findings, as the magnetic material of the present invention as set forth in claim 1, the general ^{_{formula: (R 1 X R 2 Y}} B Z M 1-XYZ) _1-Q N _Q (1) (wherein, R ¹ is at least one element selected from rare earth elements, R ² is at least one element selected from Zr, Hf and Sc, and M is Fe And at least one element selected from Co and X, Y, Z, and Q
Are 0.02 ≦ X ≦ 0.07, 0.001 ≦ Y, 0.03 ≦ X + Y ≦
0.2, 0 ≦ Z ≦ 0.1, 0.001 ≦ Q ≦ 0.2).

According to the present invention, for example, when 50 atomic% or more of the R ¹ element is Sm,
Especially effective. The magnetic material of the present invention preferably has a crystal phase having a TbCu ₇ type crystal structure as a main phase.

According to a more specific aspect of the present invention, as described in claim 4, the value of Q representing the N amount is 0.1 ≦
The value of Z representing the B amount is in the range of 0.001≤Z≤0.1, and the value of Z representing the B amount is in the range of 0.001≤Z≤0.1. Furthermore, in the magnet material of the present invention, the value of Y representing the amount of the R ² element is preferably in the range of 0.03 ≦ Y as described in claim 9.

According to a tenth aspect of the present invention, there is provided a bonded magnet comprising a mixture of the above-described magnet material of the present invention and a binder, and molding the mixture into a desired shape.

[0015]

Embodiments of the present invention will be described below.

The magnet material of the present invention has a composition substantially represented by the above formula (1). First, the reasons for blending the components constituting the magnet material of the present invention and the reasons for defining the blending amounts will be described.

The rare earth element as the R ¹ element is a component that brings a large magnetic anisotropy to the magnet material and gives a high coercive force. As such R ¹ element, L
a, Ce, Pr, Nd, Sm, Eu, Gd, Tb, D
Rare earth elements such as y, Ho, Er, Tm, Lu, and Y are listed. Among them, it is particularly preferable that 50 atom% or more of the R ¹ element is Sm, whereby the magnetic anisotropy of the main phase can be increased and the coercive force can be increased.

The present invention reduces the content of the R ¹ element, reduces the manufacturing cost of the magnet material and saves resources, and suppresses variations in magnetic characteristics when the main component of the R ¹ element is Sm. It is a thing. However, when the content of the R ¹ element is extremely reduced, the magnetic anisotropy decreases significantly, and it becomes difficult to obtain a magnet material having a large coercive force. Therefore, the content X of the R ¹ element is set to 0.02 or more. on the other hand,
If the content X of the R ¹ element exceeds 0.07, the above-described effects of reducing the production cost and saving resources cannot be obtained.
The content X of ^one element is 0.07 or less. R ¹ element content
X is more preferably in the range of 0.04 ≦ X ≦ 0.07.

The R ² element is at least one element selected from Zr, Hf and Sc. To occupy the rare earth site of such R ² element mainly main phase, without reducing the elements of the rare earth site, but making it possible to reduce the content of R ¹ element. As described above, for example, Zr mainly occupies the rare earth sites of the TbCu ₇ phase, so that it is possible to reduce the content of the rare earth element while maintaining such a crystal structure.

Further, the R ² element basically occupies the rare earth site of the main phase and has an effect of reducing the average atomic radius of the rare earth site. As a result, F in the main phase
It becomes possible to increase the concentration of e or Co. Further, R
^{The two} elements have a favorable effect on the microstructure of the magnet material, for example, by making crystal grains finer, and also contribute to the improvement of coercive force and remanence.

The content Y of the R ² element is set to at least 0.001 or more in order to obtain the above-described basic effects, but the content Y of the R ¹ element is maintained while maintaining the crystal structure of the main phase. In order to obtain a reduction effect, the content is preferably set to 0.03 or more. The upper limit of the content of R ² element based on the total amount of R ¹ element, is defined as follows.

The total amount (X + Y) of the R ¹ element and the R ² element is set to 0.03 or more in order to obtain a high coercive force magnet material while maintaining the crystal structure of the main phase. The total amount of the R ¹ element and the R ² element (X +
If Y) is less than 0.03, precipitation of α-Fe (Co) becomes remarkable, and the coercive force of the magnet material is reduced. On the other hand, when the total amount of the R ¹ element and the R ² element exceeds 0.2, the saturation magnetization is greatly reduced. Therefore, the total amount of the R ¹ element and the R ² element (X
+ Y) is in the range of 0.03 ≦ X + Y ≦ 0.2. R ¹ element and R ²
More preferably, the total amount of the elements (X + Y) is in the range of 0.06 ≦ X + Y ≦ 0.1.

The M element is at least one element selected from Fe and Co, and has a function of increasing the saturation magnetization of the magnet material. The increase in the saturation magnetization leads to an increase in the remanent magnetization, and the maximum magnetic energy product increases accordingly. Such an M element is preferably contained in the magnet material in an amount of 70 atomic% or more, whereby the saturation magnetization can be effectively increased. Further, in order to further increase the saturation magnetization of the magnet material, the amount of Fe in the total amount of the M element is preferably set to 50 atomic% or more. Part of the M element is Ti, V, Cr, Mo, W, Mn, Ga, Al,
It may be replaced with at least one element selected from Sn, Ta, Nb, Si and Ni (hereinafter referred to as T element). By substituting a part of the M element with such a T element, practically important characteristics such as corrosion resistance and heat resistance can be improved. However, if the M element is replaced by an excessively large amount of the T element, the magnetic properties will be significantly reduced. Therefore, it is desirable that the amount of the M element replaced by the T element be 20 atom% or less.

B (boron) is an element effective for improving the remanent magnetization of the magnet material, but it is not necessarily required to be blended in the magnet material of the present invention. However, if B is excessively mixed, the generation of the R ₂ Fe ₁₄ B phase becomes remarkable in the heat treatment step, and the magnetic properties of the magnet material may be deteriorated. Therefore, the content Z when B is blended is 0.001 ≦ Z
≦ 0.1. B content Z is 0.001 ≦ Z ≦ 0.04
Is more preferable, and more preferably
The range is 0.001 ≦ Z ≦ 0.02.

N (nitrogen) mainly exists at the interstitial position of the main phase, and improves the Curie temperature and magnetic anisotropy of the main phase as compared with the case where N is not contained. Among them, improvement of magnetic anisotropy is important for imparting a large coercive force to a magnet material. N exerts its effect when it is blended in a small amount, but when it is blended in excess, precipitation of the α-Fe phase increases. Therefore, the N content Q is in the range of 0.01 ≦ Q ≦ 0.2. A more preferable N content Q is in the range of 0.1 ≦ Q ≦ 0.2.

A part of N may be replaced by at least one element selected from H, C and P, thereby improving magnet properties such as coercive force. However,
If the substitution amount of N by H, C, and P is too large, the effect of improving the Curie temperature of the main phase and the magnetic anisotropy is reduced.
Is preferably 50 atom% or less.

The magnet material substantially represented by the above formula (1) allows inclusion of unavoidable impurities such as oxides.

The magnetic material of the present invention having the above-described composition is particularly suitable for a phase (TbC7) having a TbCu ₇ type crystal structure.
(u ₇ phase) as the main phase. The main phase of the magnetic material of the present invention is a phase having a Th ₂ Zn ₁₇ type crystal structure (Th
₂ Zn ₁₇ phase) and the like, but in particular, Tb
A magnet material having a Cu ₇ phase as a main phase can provide a magnet material having excellent magnetic properties such as residual magnetization as compared with a magnet material having a Th ₂ Zn ₁₇ phase as a main phase. These crystal structures can be easily confirmed by X-ray diffraction or the like.

In particular, when the TbCu ₇ phase is used as the main phase of the magnet material, the ratio c / a of its lattice constant is preferably 0.847 or more. In such a case, a larger saturation magnetization can be obtained and the residual magnetization can be further increased. The ratio c / a of the lattice constant of the TbCu ₇ phase can be controlled by the composition of the constituents of the magnet material and the manufacturing method.

The main phase in the magnet material of the present invention refers to the one having the largest volume ratio in the constituent phases including the amorphous phase in the alloy. The main phase in the magnetic material of the present invention preferably contains at least 80% by volume from the viewpoint of magnet properties and the like.

The magnet material of the present invention is produced, for example, as follows. First, an ingot containing a predetermined amount of each of the elements R ¹ , R ² , M, and B, and if necessary, a T element is prepared by arc melting or high frequency melting. The ingot is cut into small pieces, melted by high-frequency induction melting or the like, and then the molten metal is jetted from a nozzle onto a high-speed rotating metal roll to produce a quenched material (single roll method). The quenched material may be manufactured by applying a twin-roll method, a rotating disk method, a gas atomizing method, or the like in addition to the single-roll method.

The quenching step is desirably performed in an atmosphere of an inert gas such as Ar or He. By rapidly cooling in such an atmosphere, deterioration of magnetic characteristics due to oxidation can be prevented. The quenched material obtained in the quenching step is subjected to a heat treatment at a temperature of about 300 to 1000 ° C. for 0.1 to 10 hours in an atmosphere of an inert gas such as Ar or He or in a vacuum as necessary. You may. By performing such a heat treatment, magnetic characteristics such as coercive force can be improved.

Next, if necessary, the quenched material has an average particle size of several μm to several hundred μm by means of a ball mill, a brown mill, a stamp mill, a hammer mill, a jet mill or the like.
Grind to m. By subjecting the alloy powder to a heat treatment (nitriding treatment) in a nitrogen-containing atmosphere, a desired magnet material is obtained. The nitriding treatment is preferably performed at a temperature of about 200 to 700 ° C. in a nitrogen gas atmosphere of 0.001 to 100 atm. The nitriding treatment under such conditions is preferably performed for about 0.1 to 300 hours.

The atmosphere at the time of nitriding is replaced with nitrogen gas.
A nitrogen compound gas such as ammonia gas may be used.
When ammonia gas is used, the nitridation reaction rate can be increased. At this time, the rate of the nitriding reaction can be controlled by simultaneously using gases such as hydrogen, nitrogen, and argon. In addition, 0.001
High-efficiency nitridation can be performed by performing heat treatment at a temperature of 100 to 700 ° C. in a hydrogen gas atmosphere at a pressure of 100 to 700 atm or using a gas obtained by mixing a hydrogen gas with a nitrogen gas.

The magnet material of the present invention is suitable, for example, as a constituent material of a bonded magnet. Hereinafter, a method for producing a bonded magnet from the magnet material of the present invention will be described. In addition,
When manufacturing a bonded magnet, usually, a magnet material is pulverized and used. However, if grinding has already been performed in the above-described magnet material manufacturing process, this can be omitted.

(A) Powder of the magnetic material of the present invention is mixed with an organic binder, and the mixture is compression-molded or injection-molded into a desired shape to produce a bonded magnet. As the binder, for example, an epoxy-based or nylon-based resin can be used. When a thermosetting resin such as an epoxy resin is used as the binder, it is preferable to perform a curing treatment at a temperature of about 100 to 200 ° C. after molding into a desired shape.

(B) The powder of the magnetic material of the present invention is mixed with a low melting point metal or a low melting point alloy and then compression molded to produce a metal bonded magnet. In this case, a low melting point metal or a low melting point alloy functions as a binder. As the low melting point metal, for example, Al, Pb, Sn, Zn, Cu, Mg or the like can be used, and as the low melting point alloy, an alloy containing the above low melting point metal can be used.

[0038]

Next, specific examples of the present invention will be described.

Examples 1 to 5 First, each raw material of high purity was prepared so as to have each composition shown in Table 1 (N was basically excluded), and the raw material ingots were melted by high frequency in an Ar atmosphere. Produced. Then
After each of these raw material ingots was melted by high frequency induction heating in an Ar atmosphere, the molten metal was sprayed from a nozzle onto a 300 mm diameter copper roll rotating at a peripheral speed of 35 m / s, followed by rapid cooling to produce alloy ribbons. .

Subsequently, each of the above alloy ribbons was heat-treated at 760 ° C. for 30 minutes in an Ar atmosphere. As a result of performing X-ray diffraction of each of the alloy ribbons after the heat treatment, all of the alloy ribbons were indexed by the TbCu ₇ type crystal structure except for the diffraction peak of the minute α-Fe phase, and the lattice constant ratio c / a is 0.8
It was found to be in the range of 56 to 0.868.

Next, the above alloy ribbons were pulverized using a ball mill to produce alloy powders having an average particle size of 150 to 200 μm. In order to make these alloy powders contain nitrogen, each alloy powder was heat-treated at 430 ° C. for 3 hours in a mixed gas flow of ammonia gas and hydrogen gas. The flow ratio of ammonia gas to hydrogen gas was 1:15. Table 1 shows the composition of the obtained magnet material.

After adding and mixing 2.5% by weight of an epoxy resin to each of the magnetic materials thus obtained, compression molding was performed under a pressure condition of 1000 MPa, and a curing process was further performed at a temperature of 150 ° C. for 2.5 hours to obtain a bond. A magnet was made.
Table 1 also shows the coercive force, residual magnetic flux density, and maximum magnetic energy product of each of the obtained bond magnets.

Comparative Examples 1 to 3 Each alloy ribbon produced in the same manner as in Example 1 was heat-treated and pulverized in an Ar atmosphere in the same manner as in Example 1, and then subjected to nitriding treatment to produce respective magnet materials. did. The magnet materials of these comparative examples have alloy compositions outside the scope of the present invention. Bond magnets were manufactured using the obtained magnet materials in the same manner as in Example 1. Table 1 also shows the coercive force, residual magnetic flux density, and maximum magnetic energy product of each of these bonded magnets.

[0044]

[Table 1] As is clear from Table 1, even if the magnet material has a composition (X ≦ 0.07) having a small content of rare earth elements, a bonded magnet having magnetic properties comparable to those of a magnet material having a content of 0.07 <X can be obtained. It turns out that it has been obtained. However, when the content X of the rare earth element is set to X <0.02, the coercive force is significantly reduced.

Further, the magnetic material of each of the examples had a small variation in the magnetic characteristics despite the fact that Sm was a main component of the rare earth element. This was evaluated by producing 100 bonded magnets according to each example and measuring their coercive force. As a result, it was found that the bond magnets according to the respective examples had smaller coercive force variations than the bond magnets according to Comparative Examples 1 and 2.

[0046]

As described above, according to the magnet material of the present invention, the amount of rare earth elements can be reduced without impairing the magnetic properties. Therefore, by using such a magnet material, it is possible to provide a bonded magnet with reduced cost and resource saving.

[0047]

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Takahiro Hirai 8 Shinsugita-cho, Isogo-ku, Yokohama-shi, Kanagawa Inside the Toshiba Yokohama office

Claims (10)

[Claims] [Claim 1] The general formula: (R ¹ _X R ² _Y B
_Z M _1-XYZ ) _1-Q N _Q (wherein, R ¹ is at least one element selected from rare earth elements, R ² is at least one element selected from Zr, Hf and Sc, and M is X, Y, Z and Q represent at least one element selected from Fe and Co
Are 0.02 ≦ X ≦ 0.07, 0.001 ≦ Y, 0.03 ≦ X + Y ≦
0.2, 0 ≦ Z ≦ 0.1, 0.001 ≦ Q ≦ 0.2). 2. The magnet material according to claim 1, wherein at least 50 atomic% of the R ¹ element is Sm. 3. The magnetic material according to claim 1, wherein a phase having a TbCu ₇ type crystal structure is a main phase. 4. The magnet material according to claim 1, wherein a value of Q representing the N amount is in a range of 0.1 ≦ Q ≦ 0.2. 5. The magnetic material according to claim 1, wherein a value of Z representing the B amount is in a range of 0.001 ≦ Z ≦ 0.1. 6. The magnet material according to claim 1, wherein 50% by atom or more of the M element is Fe. 7. The magnetic material according to claim 1, wherein 20 atomic% or less of the M element is Ti, V, Cr, Mo,
A magnet material characterized by being substituted by at least one element selected from W, Mn, Ga, Al, Sn, Ta, Nb, Si and Ni. 8. The magnetic material according to claim 1, wherein 50% by atom or less of the N element is replaced with at least one element selected from H, C and P. Characteristic magnet material. 9. The magnet material according to claim 1, wherein a value of Y representing the amount of the R ² element is in a range of 0.03 ≦ Y. 10. The method according to claim 1, wherein:
A bonded magnet, comprising: mixing the magnet material described in the above item and a binder; and molding the mixture into a desired shape.