JPH02202002A - Bonded magnet - Google Patents

Abstract

PURPOSE:To contrive improvement in filling rate of permanent magnet material, and to obtain high magnetic characteristics by a method wherein the permanent magnet material having specific particle size is used. CONSTITUTION:When the powder of permanent magnet material has the composition of RxT100-x-y-zByMz, substantially it has only the main phase of tetragonal crystal structure, or both of the above-mentioned main phase and an amorphous and/or crystalline poor-R subphase, or it has subphase only, the value obtained by having the volume ratio (subphase/main phase) (v) divided by (11.76-x)/x is 2 or less, and the title magnet is formed by molding the mixture of the powder of magnet material, having the average major axis of 20 to 300mum, and a binder. As a result, the filling rate of the powder of permanent material can be improved, and the high characteristics of the permanent magnet material can also be utilized efficiently.

Description

Detailed Description of the Invention <Industrial Application Field> The present invention relates to a bonded magnet obtained by molding a mixture of a binder and a powder of a permanent magnet material, and more particularly to a compression bonded magnet obtained by press molding. Regarding magnets and injection bonded magnets obtained by injection molding, especially Fe containing rare earth elements.
The present invention relates to a bonded magnet using a quenched magnet material of -R-B system (R is a rare earth element containing Y. The same applies hereinafter) and Fe-Co-R-B system alloy.

<Prior Art> As rare earth magnets with high performance, Sm--Co magnets with an energy product of 32 MGOe are mass-produced using powder metallurgy.

However, this method has the disadvantage that the raw material costs of Sm and Go are high. Among the rare earth elements, elements with small atomic weights, such as cerium, praseodymium, and neodymium,
It is more abundant and cheaper than samarium. Also, Fe
is cheaper than CO.

Therefore, Nd-Fe-B magnets have been developed in recent years, and sintered magnets have been developed in JP-A-59-46008, and
No. 0-9852 discloses a method using a high-speed quenching method.

Although the conventional Sm-Co powder metallurgy process can be applied to magnets made by the sintering method, Nd-Fe, which is easily oxidized,
Because it involves the process of pulverizing the alloy ingot to a size of about 2 to 10 μm, it is difficult to handle, and the powder metallurgy process has a large number of steps (melting → casting → coarse ingot grinding - fine grinding → pressing → sintering). Since it is a magnet), it cannot take advantage of its characteristic of using inexpensive raw materials.

On the other hand, the high-speed quenching method has the advantage of simplifying the process [melting - high-speed quenching -> coarse pulverization -> cold press (warm press) -> magnet] and does not require a pulverization process. However, in order to use the magnet produced by the high-speed quenching method as an industrial material, it is desired that the layer has a higher coercive force, a higher energy product, a lower cost, and improved magnetization characteristics.

Among the various properties of R-Fe-B permanent magnets, the coercive force is sensitive to temperature, and the coercive force (iHc
) is 0.15%/℃, while R-
There is a problem in that the temperature coefficient of coercive force (iHc) of Fe-B permanent magnet material is 0.6 to 0.7%/°C, which is more than four times higher. Therefore, the R-Fe-B permanent magnet material has a high risk of demagnetization as the temperature rises, forcing a limited design on the magnetic circuit. Furthermore, it cannot be used, for example, as a permanent magnet for parts in the engine room of a car used in the tropics.

As described above, it has long been known that R-Fe-B permanent magnet materials have practical problems due to the large temperature coefficient of coercive force, and it is hoped that a magnet with a large absolute value of coercive force will emerge. [Nikkei New Material, 1986.4-
281L9) page 80].

Japanese Unexamined Patent Publication No. 60-9852 proposes that an R-B-Fe alloy be provided with a high coercive force iHc and an energy product by a liquid quenching method. The composition disclosed in this document contains rare earth elements R (Nd, Pr) = 10% or more, B = 0.
5 to 10%, the balance being Fe. Conventional R-
B-Fe alloy has excellent magnetic properties because of NdJe+
It is described as a 汞 compound in the J phase compound. Therefore, many proposals have been made to improve the magnetic properties of both the sintering method and the high-speed quenching method (Japanese Patent Application Laid-open Nos. 59-89401 and 60-144).
No. 906, No. 61-79749, No. 57-14190
No. 1, Publication No. 61-73861), and the target alloy is in the vicinity of the composition corresponding to this compound, that is, R = 12 to 17%, B = 5 to 8%. , based on experiments on such alloys.

Rare earth elements are expensive, and it is desirable to reduce their content. However, when the rare earth element content is less than 12%, there is a problem that the coercive force iHc rapidly deteriorates. In fact, in JP-A No. 60-9852, R=10%
It has been shown that in this case, Fc becomes 6 kOe or less. That is, it is known that coercive force iHc deteriorates when the content of rare earth elements in R-B-Fe-based alloys becomes less than 12%, but it is possible to prevent a decrease in coercive force iHc in such a composition range. A method for designing such a composition and structure was previously unknown.

In the sintering method and high-speed quenching method, basically Nd*Fe,
B compound is used, but Applied Physics Vol. 55, No. 2 (
1986), page 121, these magnets are not only different in manufacturing method, but also completely different types from the viewpoint of alloy structure and coercive force generation mechanism.

In other words, a sintered magnet has a crystal grain size of approximately IO μm, and in terms of conventional Sm-Co magnets, it is a nucleation type magnet such as SmCo5 type magnet where the nucleation of reverse magnetic domains determines the coercive force. The quenched magnet is J, Appl,
Phys, 62(3) vol, 1 (1987) P96
As shown in No. 7-971, fine particles of O, 01-1 μm are Nct.

It is a pinning type magnet like an Sm*CO+y type magnet, which has an extremely fine structure surrounded by an amorphous phase richer in Nd than the Fe+4B compound, and the coercive force is determined by the binding of the domain wall. Therefore, when approaching both magnets to improve their characteristics, it was necessary to consider that the coercive force generation mechanism is sufficient.

Therefore, the present inventors proposed that RxT+oo-x-y-xBy
L (however, R%T%X%y, z and M are the same as those in the present invention) and has only a main phase with a substantially tetragonal crystal structure, or Alternatively, if it has such a main phase and an amorphous and/or crystalline R-poor subphase, and if it has a subphase, the volume ratio of the main phase to the subphase (subphase/main phase) v proposed a permanent magnet made of a permanent magnet material with a smaller value of .

By the way, permanent magnet materials in the form of ribbons or flakes obtained by the high-speed quenching method are usually crushed and made into bulk magnets by hot pressing or the like, or used as bonded magnets bonded with a binder such as resin. It will be done.

Bulk magnets generally have the disadvantage of being hard (and brittle), but bonded magnets are light and elastic, do not chip or crack, can be easily molded into complex shapes, and are excellent for mass production.
Its uses are on the rise.

A bonded magnet is obtained by mixing or kneading a powder of a permanent magnet material and a binder, adding a coupling agent, a plasticizer, an antioxidant, etc. as necessary, and then molding the mixture. More specifically, there are compression bonded magnets that use a thermosetting resin as a binder and press molding as a molding method, and injection bonded magnets that use a thermoplastic resin as a binder and injection molding as a molding method.

<Problems to be Solved by the Invention> However, there have been no proposals regarding the optimum particle size or particle size distribution for obtaining a high filling rate, high magnetic properties, etc. for the powder of the permanent magnet material used in these bonded magnets. Not done. Therefore, even if powder of a permanent magnet material with high characteristics is used, it is difficult to fully exhibit its characteristics.

The present invention is a bonded magnet manufactured using powder of a permanent magnet material that exhibits high coercive force and high energy product, is high performance and practical, has good magnetization characteristics and corrosion resistance, and has good performance stability. Therefore, it is an object of the present invention to provide a bonded magnet in which such characteristics of the powder of this permanent magnet material are fully exhibited.

Means for Solving the Problems> Such objects are achieved by the following inventions (1) to (9).

(1) R,T,o,,-,-,ByM, (However, R
is one or more rare earth elements including Y, and T is Fe or Fe and Co. Also, 5.5≦x
<11.76.2≦y〈15.2≦15, and M is T
i, V, Cr, Zr.

One or more of Nb, Mo, Hf, .Ta and W.

), and has only a main phase with a substantially tetragonal crystal structure, or has such a main phase and an amorphous and/or crystalline R-poor subphase, And when it has a subphase, the value obtained by dividing the volume ratio of the main phase to the subphase (subphase/main phase) v by (11,76-X)/X is 2 or less, and the average major axis is 20 ~300μ
1. A bonded magnet characterized in that it is formed by molding a mixture of a powder of a permanent magnet material and a binder.

(2) The bonded magnet according to claim 1, wherein the powder of the permanent magnet material substantially does not contain any of powder having a major axis exceeding four times the average major axis and powder having a major axis exceeding 400 μm.

(3) The bonded magnet according to (1) or 2 above, wherein the powder of the permanent magnet material is flat and has a thickness of 20 to 80 μm. (4) The value obtained by dividing the value of V by 1 The bonded magnet according to any one of (1) to 3) above, which is smaller.

(5) It has a main phase and a subphase, and the subphase is in atomic ratio. (6) The binder is a thermosetting resin, and the molding is performed by press molding. Any one of (1) to 5) above. Bonded magnet as described in .

(7) The binder is a thermoplastic resin, and the magnet is a magnet.

(8) The bonded magnet according to any one of (1) to 7) above, wherein the permanent magnet material is a ribbon obtained by high-speed quenching.

(9) Permanent magnetic material powder and binder containing at least R, T and B (wherein R is one or more rare earth elements including Y, and T is Fe or Fe and Co) A bonded magnet formed by molding a mixture of.

The average major axis of the powder of the permanent magnet material is 20 to 300 μm.
and the powder of this permanent magnet material has a major axis more than four times the average major axis and the major axis is 400 μm.
A bonded magnet characterized in that it contains substantially no powder exceeding .

<Function> In the present invention, a bonded magnet is obtained by press molding or injection molding a powder of a permanent magnet material and a binder.

In the present invention, since the powder of the permanent magnet material having a predetermined particle size is used, the filling rate of the powder of the permanent magnet material is improved.

Therefore, a bonded magnet that effectively exhibits the high magnetic properties of the permanent magnet material used in the present invention can be obtained.

Specific composition> Hereinafter, a specific configuration of the present invention will be explained in detail.

The bonded magnet of the present invention is constructed by bonding powder of a permanent magnet material with a binder, and the powder of the permanent magnet material has a predetermined particle size.

The average major axis of the powder of the permanent magnet material used for manufacturing the bonded magnet of the present invention is 20 to 300 μm.

More specifically, when the bonded magnet of the present invention is a compression bonded magnet manufactured by press molding, the average major axis of the powder of the permanent magnet material used is 60
It is preferably 280 μm, more preferably 8
It is 0 to 240 μm.

Further, when the bonded magnet of the present invention is an injection bonded magnet manufactured by injection molding,
The average major axis is preferably 50 to 220 μm, more preferably 60 to 200 μm.

When the average major axis is less than this range, the powder filling rate decreases and the compacting density decreases. Moreover, if it exceeds this range, the fluidity of the granulated powder in the compression bonded magnet will decrease, and the compacted density will decrease. In injection bonded magnets, the fluidity of the powder injection material decreases, causing molding defects and a decrease in molding density.

Note that the average major axis in this case refers to a scanning electron microscope (SEM) image of the powder of the permanent magnet material.

It was determined by measuring the true value. More specifically, when the powder of the permanent magnet material is flat, for example, the long axis of the powder is the diameter of the main surface of the powder, particularly the long axis of the main surface. In the present invention, the value obtained by dividing the total length of the long axis of each powder measured in this way by the number of measured powders, that is, the number average, is defined as the average length axis in the present invention. The number of powders measured was 4.
It is preferable that the number is 00 or more.

In addition, in the present invention, powder having a major axis more than four times the average major axis determined in this way and a major axis of 400μ
It is preferred to use a powder of permanent magnetic material that does not substantially contain any powder exceeding m. In this case,
Substantially free means that the number of such powders is 10% or less, preferably 5% or less of the total number of powders.

When using a powder of a permanent magnet material containing at least one of a powder having a major axis exceeding 4 times the average major axis and a powder having a major axis exceeding 400 μm, the filling rate decreases and it becomes more likely to be crushed during molding. Furthermore, the resistance with the mold is large, leading to an increase in molding costs due to wear of the mold.

When the powder of the permanent magnet material used in the present invention has a flat shape, the thickness thereof is preferably 20 to 80 μm. Powder having a thickness less than this range is difficult to manufacture because the thickness of the raw material ribbon needs to be approximately the same.

Further, if the thickness is less than 20 μm, the characteristics deteriorate. If this range is exceeded, the thickness of the raw material ribbon becomes too large, making it difficult to control its properties.

The powder of the permanent magnet material as described above is mixed with a binder and then molded into a bonded magnet. When this bonded magnet is cut along an arbitrary plane, the average major axis of the powder of the permanent magnet material that appears in the cross section is almost the same as the average major axis of the powder of the permanent magnet material before mixing.
Compression bonded magnets usually have cracks and cracks throughout.

In addition, in injection bonded magnets, a part of the powder of the permanent magnet material is crushed during injection molding, and fine powder with an average major axis of 10 μm or less forms about 5 to 30% of the total [area ratio (number of pieces x cross-sectional area of powder)]. Sometimes. In this case, the filling rate of the powder of the permanent magnet material is improved as a result. Furthermore, for the purpose of improving the filling rate of the powder, an injection bonded magnet can also be formed using a powder of a permanent magnet material that previously contains fine powder having an average major axis of this extent. Even in such a case, the average major axis of the powder is preferably within the above range.

There are no particular restrictions on the binder used in the present invention (any of the various resins used in known bonded magnets may be used; for example, in the case of compression bonded magnets, various thermosetting resins such as epoxy resins using various curing agents) may be used. In the case of injection bonded magnets, various thermoplastic resins such as polyamide resin may be used. Note that there are no particular restrictions on the state of the binder at the time of mixing.

There are no particular restrictions on these mixing methods, including horizontal rotating cylindrical mixers, regular cube mixers, vertical double cone mixers, V-type mixers, plow plate mixers, spiral mixers, ribbon mixers, and impact mixers. Any rotary mixer or the like may be used. There are no particular restrictions on the conditions for press molding or injection molding, and they may be appropriately selected from known conditions.

After molding, heat treatment is performed to thermoset the binder. This heat treatment may be performed within the mold or after being removed from the mold.

The bonded magnet of the present invention may contain a lubricant, a coupling agent, a plasticizer, an antioxidant, etc., as necessary, in addition to the above-described powder of the permanent magnet material and binder.

The permanent magnet material powder contained in the permanent magnet of the present invention is
It has the composition as described above.

To further explain R, R is one or more rare earth elements including Y, and is particularly preferably represented by (R'a(CebLa+-b)+-a).

In this case, R1 is one or more rare earth elements including Y, excluding Ce and La, and 0.80≦a≦1.00.0≦b≦1. In addition, in order to reduce costs, Ce, La
It is preferable to include.

The reason for the limitation on the composition will be explained.

The value of X, which represents the amount of rare earth elements, is 5.5 or more and 11.76.
However, if X is less than 5.5, the coercive force iHc tends to decrease, and if the value of X is 11.76 or more, the residual magnetization Br decreases significantly.

In addition, when X is 5.5 to 11, even more preferable results are obtained. Moreover, since a magnet with good corrosion resistance can be obtained at low cost, it is also preferable that X is 5.5 to 8.

Moreover, when 1-a exceeds 0.2, the maximum energy product decreases. In addition, Sm can also be contained in R1. However, the amount of Sm is 20% or less of X. This is because it lowers the anisotropy constant.

In addition, as R, Nd, Pr, and Dy are suitable.

The value of the amount y of B is 2 or more and less than 15.

When y is less than 2, the coercive force iHc is small (, when y is 15 or more, B
r decreases.

In this case, y is preferably 2 to 14.

Although T may be Fe alone, replacing Fe with Co improves the magnetic performance and also improves the Curie temperature. However, when T is Fe+-c Coe,
When the substitution amount C exceeds 0.7, the coercive force decreases (.For this reason, it is preferable that C is 0 to 0.7.

M is one or more of Zr, Nb, Mo, Hf, Ta, W, Ti, V and Cr. By adding these, crystal growth is suppressed, and a high coercive force can be obtained without deteriorating the coercive force even at high temperatures and for a long time.

Furthermore, by adding one or more of Cu, Ni, Mn, and Ag, it is possible to improve the workability during plastic working without deteriorating the magnetic properties.

However, when the total metric 2 of M exceeds 15, it mimics a rapid decrease in magnetization (.

Also, in order to increase the coercive force iHc, Z is 0. It is preferably 1 or more, and in order to increase corrosion resistance, it is 0.
It is preferably 5 or more, more preferably 1 or more. When two or more types of M elements are added in combination, the effect of improving coercive force iHc is greater than when added alone. In the case of composite addition, the upper limit of the amount added is 15% as described above, preferably 10%.
%.

To explain M in detail, Zr, Nb, Mo, Hf, Ta
, W% One or more of Ti, V and Cr is M, and Cu
, when one or more of Mn and Ag is M2, the atomic ratio M, :M, of M and M when M2 is contained is 2
:l to 10:1, more preferably 3:1 to 5:1, from the viewpoint of improving workability during plastic working without reducing residual magnetization and coercive force.

Further, in order to improve corrosion resistance, it is preferable to contain Ni, and in this case, the total content of Ni and M is preferably 30 at % or less.

Note that 50% or less of B is Si, and C% is Ga.

Substitution with Aj2, P, N, Se, S, 0, etc. has the same effect as B alone.

Furthermore, as a preferable region for obtaining a high coercive force,
is 7-11. More preferably 8 to 10, y is 2 to less than 15, more preferably 4 to 12, even more preferably 4 to 1
0. C is in the range of 0-0.7, more preferably O-0.6.2 is in the range of 0.1-10, more preferably 2-10.

A preferred region for isotropic and high energy products is where X is less than 11, more preferably less than 10, and y is 2
~ less than 15, more preferably 4 to 12, even more preferably 4 to lO, C is 0 to 0.7, more preferably O
~0.6.2 does not include 0 and is up to 10, more preferably 2
~IO.

In order to obtain a high energy product with isotropic properties and good magnetization characteristics, X is preferably in the range of 6 to 11, more preferably 6.
- less than 10, y is 2 to less than 15, more preferably 4 to 1
2, more preferably in the range of 4 to 10, C is 0 to 0.7
, more preferably 0 to 0.6.2 does not include O and is up to 10, more preferably 2 to 10.

In order to obtain a high energy product with anisotropy, X is preferably 6 to 11.76, more preferably 6 to less than IO, and y is 2 to less than 15, more preferably 4 to 12, and even more preferably 4. ~10, c is from 0 to 0.7, more preferably from O to 0.6, and Z is up to 10 without O, more preferably from 2 to 1O.

Such composition can be easily measured by atomic absorption method, fluorescent X-ray method, gas analysis method, etc.

Such a permanent magnet material has only a main phase with a substantially tetragonal crystal structure, or has such a main phase and an amorphous and/or crystalline R-poor subphase. , and the volume ratio of the main phase to the subphase (subphase/
Main phase) The value of v is less than or equal to twice (11,76-x)/x.

When this value exceeds twice, Br decreases, (BH),
, decreases.

Also, ■ is It is preferable that it is smaller than 1 times.

In this case, the (subphase/main phase) ratio V may be determined by electron microscopic observation.

More specifically, 10,000 ~
5 ~ randomly extracted at a magnification of about 200,000 times
For example, a field of view of about 1000 liters may be subjected to image processing to separate the main phase and subphase based on the gradation, calculate the area ratio, and use this as the volume ratio.

FIG. 2 shows a scanning electron micrograph of the permanent magnet material used in the present invention.

By the way, a stable tetragonal compound as an R-T-B compound is R* Tl48 (R=11.76 at%, T=82
．． In the present invention, the main phase has a substantially tetragonal structure, and the subphase has an R-poor composition.

Therefore, a ternary diagram of RTB is shown in FIG.

In the ternary diagram of Figure 1, R yo T,,B are R(11,7
6, 82, 36, 5, 88).

Moreover, in the ternary diagram of FIG. 1, the part surrounded by ABCD is the composition range of RTB excluding M in the present invention.

Now, in the ternary diagram of RTB, the present invention will be described.
When the composition at point Q is cooled quasi-statically from the melting point, R(R1T
14B) and P (T).

In this case, stoichiometrically, the atomic ratio of T and R2Tl4B (T/RiT+-8) is QR/PQ. Therefore, when calculating this QR/PQ, QR/PQ = Q'R' /PQ '=
[0,1176(100-z)-x] /
x, and the above values are obtained. Further, if z=0, the above value is also obtained.

(Subphase/Main phase) V is [0,1176(100-z)-x
] The range of the value A divided by /X is as described above, but it is preferably in the range of 0.15 to 0.95, more preferably in the range of 0.3 to 0.8.

Within this range, not only the coercive force iHc and residual magnetization exhibit stable high values, but also the squareness HJi
Hc becomes higher and as a result the maximum energy product (B
This is because H) max is further improved.

In order to control the value A within the above range, it is preferable to first perform high-speed quenching.

As for high-speed quenching, which will be described in detail later, a liquid quenching method is applied, and a single roll method is usually used.

Specifically, this is done by controlling the circumferential speed of the rotating cooling roll. The circumferential speed in this case is 2 to 50 m/s, more preferably 5 to 20 m/s.

Such a circumferential speed is less than 2 m/s,
Most of the obtained ribbon is crystallized, and the average crystal grain size is too large, 3 μm or more, and when the speed exceeds 50 m/s, the value A becomes too thick.

Further, by setting the peripheral speed within a preferable range, even higher characteristics (high coercive force, high energy product, etc.) can be obtained.

Further, in the present invention, the A value obtained by high-speed quenching can be reduced to the above range by heat treatment. For example, once the A value is set to 0.2 to 1.
After controlling it to a range of 2, it is 0.15 to 0.9 by heat treatment.
5.

In this case, the circumferential speed of the rotating cooling roll in the single roll method is 10 to 70 m/s, more preferably 20 to 5 m/s.
Let it be 0 m/s.

The reason why such a circumferential speed is less than 10 m/s is that most of the ribbon is crystallized, and the subsequent heat treatment creates a structure that does not require crystallization or crystal growth of the amorphous portion.
This is because if it exceeds m/s, the A value becomes too large.

Heat treatment is carried out at 400 °C in an inert atmosphere or vacuum.
Annealing is performed in a temperature range of ~850°C for approximately 0.01 to 100 hours.

The reason for creating such an atmosphere is to prevent oxidation of the ribbon and the like.

Moreover, this temperature range is selected because crystallization or grain growth does not occur below 400°C, and 85°C
This is because if the temperature exceeds 0°C, the A value may fall outside the above range.

If it is less than 0.01 hour, the effect of heat treatment is small (,10
Even if the time exceeds 0 hours, the characteristics will not be improved any further and it will only be economically disadvantageous.

As described above, in the present invention, it is not necessarily necessary to use heat treatment (the process is easy).

In the present invention, the main phase of the substantially tetragonal crystal structure is a metastable R2T14B phase in which M is dissolved in supersaturated solid solution, and its average crystal grain size is 0.01 to 3 μm, preferably 0.0
It is 1 to 1 μm, more preferably 0.01 to 0.3 μm. The reason why such a grain size is used is that if the particle size is less than 0.01 μm, almost no coercive force iHc is generated due to the imperfection of the crystal, and if it exceeds 3 μm, the coercive force iHc decreases.

In addition, in the present invention, not only such a main phase but also
Furthermore, it may have an amorphous and/or crystalline R-poor subphase, and it is preferable to have a subphase.

The subphase exists as a grain boundary layer of the main phase.

R-poor subphases include a Fe, Fe-M-B,
Examples include Fe-B%Fe-M and M-B type amorphous or crystalline.

Among these, in terms of atomic ratio, the R content of the subphase is 9710 or less of the R content of the main phase, preferably 2/3 or less, particularly 0 to 2/3, more preferably 1/2 or less, especially O It is preferable that the number is 172 or less.

When this exceeds the above range, the coercive force increases but the residual magnetization decreases, resulting in a decrease in the maximum energy product.

The composition of these main and subphases is measured using a transmission analytical electron microscope, but the size of the subphase may be smaller than the beam diameter of the electron beam (5 to 20 nm), and in that case, It is necessary to consider the influence of the main phase components.

The preferred content of each element other than R in the subphase is 0≦T≦ioo, particularly 0<T<100. More preferably, 20≦T≦90, and 0≦B≦60. Particularly ORB≦60, more preferably 10
≦B≦50, 0≦M≦50, especially OHM≦50, more preferably 10
≦M≦40.

By setting such a composition range, the coercive force (iHc
), magnetic properties such as residual magnetization (Br) are improved, and the maximum energy product (BH) wax is improved.

More specifically, in order to improve the coercive force, 0≦T≦60, particularly O<T≦60, more preferably 10
≦T≦50. 10≦B≦60, more preferably 20≦B≦50. 10≦M≦50. More preferably, 20≦M≦.

In order to improve residual magnetization, 60≦T<100, more preferably 70≦T≦90. 0<B≦30. More preferably O<B≦20. It is preferable that 0<M≦30, more preferably 0<M≦20.

In addition, in this case, the main phase has a total content of R and M of 11
It is preferable that the composition be 12 at%.

Outside this range, it becomes difficult to maintain the tetragonal structure.

Furthermore, in these cases, the R content of the main phase is 6 to 11
．． It is preferably 76 at%, particularly 8 to 11.76 at%.

If this value is less than 6 at%, the coercive force will decrease significantly,
When it exceeds 11.76 at%, the coercive force increases, but the residual magnetization decreases and the maximum energy product also decreases.

Further, T and B in the main phase are 80≦T≦85, more preferably 82≦T≦83. It is preferable that 4≦B≦7, more preferably 5≦B≦6. By setting this range, a magnet with a high energy product can be obtained even if the rare earth element content is small.

The composition of the main phase and subphase can be investigated by transmission analytical electron microscopy.

The average size of the subphase existing as a grain boundary layer is 0.3 μm or less,
Preferably it is 0.001 No. 2 um.

, 0.3 μm, the coercive force iHc decreases.

The permanent magnet material used in the bonded magnet of the present invention is obtained by cooling and solidifying Fe-R-B and Fe-Co-R-B alloy melts having the above compositions at high speed by the so-called liquid quenching method as described above. It will be done.

This liquid quenching method is a method in which molten metal is injected from a nozzle onto the surface of a metal rotating body cooled by water cooling, etc., and is rapidly solidified at high speed to obtain a thin strip-shaped material.
There are single roll method (single roll method), double roll method, etc., but in the case of this invention, as mentioned above, the single roll method, that is, one roll method is used.
The most suitable method is to inject the molten metal onto the circumferential surfaces of individual rotating rolls. By setting the roll circumferential speed as described above and rapidly solidifying the molten alloy having the above composition using the single roll method, the coercive force iHc is approximately 20,000.
up to 0e, magnetization σ is 65 to l 50 e+su/gr
magnet is obtained. In addition to such a roll method, various high-speed quenching methods such as an atomizing method, thermal spraying, mechanical alloying, etc. can also be applied to the present invention.

Moreover, the magnetic material obtained in this way also has good temperature characteristics.

That is, when residual magnetization is Br and temperature is T, for example, at 20°C≦T≦120°C, dBr / dT = -0,09 to -〇, 06%/°C d i Hc / dT = It has a temperature characteristic of about -0.48 to -〇, 25%/℃.

If the molten metal is directly rapidly solidified in this way, an extremely fine crystalline structure or a structure having such a main phase and crystalline and/or amorphous subphases can be obtained, resulting in the above-mentioned structure. A permanent magnet material with excellent magnetic properties can be obtained.

The ribbon thus obtained generally has a thickness of 20 to 80 μm.
Although the thickness is about 30 to 60 μm, it is preferable because the distribution of crystal grain size in the film thickness direction is small (the variation in magnetic properties due to grain size is reduced and the average characteristic value is increased). .

The structure after quenching varies depending on the quenching conditions, but usually consists of microcrystals or a mixed structure of microcrystals and amorphous materials. and,
Further, by appropriately applying heat treatment, that is, annealing, the microcrystalline or amorphous and microcrystalline structure and size can be further controlled, and higher properties can be obtained.

The permanent magnet material rapidly solidified by the liquid quenching method is optionally subjected to heat treatment, that is, annealing, as described above. By annealing the rapidly cooled magnet having the components targeted by the present invention, it is not only possible to satisfy the above-mentioned conditions, but also to easily obtain more stable characteristics.

The bonded magnet of the present invention is obtained by pulverizing the ribbon-shaped magnet thus obtained into powder as described above, mixing this powder with a binder, and press-molding or injection-molding.

A ribbon-shaped magnet obtained by the conventional high-speed quenching method, a magnet obtained by crushing the same into a bulk body, and a bonded magnet are disclosed in Japanese Patent Application Laid-Open No. 59-211549. However, conventional magnets have J, A, P 60 (1
0), vol 15 (1986) page 3685, in order to magnetize to saturation magnetization, 40 kO
Although a magnetizing magnetic field of more than 110 koe is required, the magnet alloy containing Zr, Ti, etc. in the present invention has the advantage that it can be sufficiently magnetized to saturation magnetization at 15 to 20 kOe. The properties after magnetization at ~20 kOe are significantly improved.

Furthermore, by applying plastic processing to the thin strip magnet obtained by the liquid quenching method, either directly or after crushing it, to make it denser and anisotropic, the magnetic properties can be improved by about 2 to 3 times. .

The temperature and time conditions during this plastic working must be selected so that the microcrystalline phase described above in the description of annealing is obtained and grain coarsening is prevented. In this regard, N in the present invention
Additive elements M such as b, Zr, Ti, and V have the advantage of suppressing crystal growth and improving warm plastic working conditions because high coercive force can be obtained without deteriorating coercive force even at high temperatures and for long periods of time. ing.

The plastic working may be performed using a known method such as die-up setting.

Note that the present invention is not limited to the powder of a permanent magnet material having the composition and structure described above, but also the powder of a permanent magnet material containing at least R, T, and B (where R and T are the same as above). The effect is achieved even when powder is used.

In this case, the average major axis of the powder of the permanent magnet material is 20 to 30
0 μm, and the powder of the permanent magnet material has a major axis that is more than 4 times the average major axis, and the major axis is 400 μm.
It shall be substantially free of any powder exceeding m.

<Examples> Hereinafter, specific examples of the present invention will be shown and the present invention will be explained in further detail.

[Preparation of permanent magnet material ribbon] 10.5Nd -6B -3Zr -IMn -ba#
An alloy having a composition of Fe (numbers represent atomic percentages) was prepared by arc melting. The obtained molten alloy was passed through a quartz nozzle onto the surface of a roll rotating at a speed of 10 to 30 m/sheet using pressurized argon gas (a jet pressure of 0.2 to 2
kglof) and rapidly quenched to obtain the ribbon samples shown in Table 1. Note that the thickness of the ribbon sample was 30 to 60 μm.

The volume of the subphase in the ribbon samples shown in Table 1 was controlled by changing the cooling conditions described above, that is, the rotational speed of the rolls.

Table 1 shows the magnetic properties of these ribbon samples.

Also, among these ribbon samples, sample N003
After electrolytically polishing the cross section, scanning electron microscopy (SEM)
Observed by. This photograph is shown in Figure 2.

In this photo, the presence of subphases is clearly observed.

Similarly, SEM images were obtained for other samples, and the average crystal grain size of the main phase and the average thickness of grain boundaries, which are subphases, were investigated.

The results are shown in Table 1.

Furthermore, this sample was subjected to X-ray diffraction analysis. The results are shown in FIG.

From FIG. 3, the main phase is Rx Fe 14B,
It can be seen that the subphase is amorphous.

Furthermore, the SE'M image was image-processed to determine the (subphase/main phase) ratio V.

In addition, the R content (R1) of the subphase and the R content of the main phase of each sample
The ratio R+/R2 with the content (R chicken) was determined.

These results are shown in Table 1.

Further, Table 2 shows the compositions of the main phase and subphase of Samples No. 002 and No. 4.

Note that these were measured using a transmission analytical electron microscope.

Each sample shown in Table 1 was first measured using a vibrating magnetometer.
The magnetized diameter was measured at 8 kOe, then pulsed magnetized at 40 koe, and the tm rate was determined for each. It was found that samples Nos. 1 to 4 were easily magnetized.

In addition, in the following composition, when samples were prepared in which the volume of the subphase was changed in the same manner as in the case of the above composition, the same results as above were obtained.

Composition (atomic percentage) 10.5Nd-6B-3Nb-ITi-bal Fe1
0 Nd-0,5Pr-6B-2,5Zr-IV-b
at Fe10.5Nd-5B-10Go-3Nb-I
Ti-bal Fe10.5Nd-58-ITi-IM
o-bal Fe10.5Nd-58-ITi-IW-
bal Fe10.5Nd-58-ITi-IMo-7
Co-balFelo, 5Nd-58-ITi-IW-
7Co-bal Fe11 Nd-6B-2Nb-I
Ni-bal Fe10.5Nd-6B-3Zr-0,
5Cr-bat Fe10.5Nd-6B-32r-I
Ti-10Co-bal Fe11 Nd-lPr
-5B-3Zr-ITi-bat Fe10.5Nd
-6B-2,5Nb-1,5V-bal Fe10
Nd-lLa-58-10(:o-3Nb-ITf
-bal Fgll Nd-5,5B-2Ti-
INi-bal Fe [Preparation of compression bonded magnet] Thin strip sample No. 3 was ground in a vibrating ball mill to obtain powders of permanent magnet materials having various average major diameters shown in Table 3. Sample No. 5 shown in Table 3
Figure 4 shows an SEM photograph of the powder of the permanent magnet material used.

For each of these powders, the total number of powders having a major axis exceeding four times the average major axis and the number of powders having a major axis exceeding 400 μm was determined. The percentage of this total to the total number of measured powders is shown in Table 3 as the amount of coarse powder. Note that the average major axis in this case is a number average value determined from a SEM photograph, and the number of measured powders was 400.

Next, each powder was mixed with an epoxy resin, press-molded, and further heat-treated to obtain a compression bonded magnet sample. The amount of epoxy resin was 2 wt % based on the powder of the permanent magnet material.

The pressure holding time for press molding was 1 second, and the applied pressure was 4
000 kg/cm". Also, the heat treatment
The test was carried out at 50°C for 1 hour.

After cutting the obtained sample with a diamond saw and embedding it in resin, it was polished and the long axis of the powder of the permanent magnetic material that appeared on the cross section was measured.The long axis before molding was almost preserved, but the powder There are cracks and cracks, and powder 1
It was divided into about 3 to 10 pieces. In addition, the measurement is S
This was done using EM photography. Sample No. 1 shown in Table 3
A SEM photograph of the cross section of No. 5 is shown in FIG.

These samples were subjected to pulse magnetization at 40 kOe.

[Preparation of injection bonded magnets] Powders of permanent magnet materials having various average major diameters were obtained in the same manner as in the case of compression bonded magnets. The average major axis and amount of coarse powder for each powder are shown in Table 4. These measurements were performed in the same manner as for the combined bonded magnet. These powders were mixed with polyamide resin and then injection molded to obtain injection bonded magnet samples.

Polyamide resin is 7wt% based on the powder of permanent magnet material.
Closed.

Injection molding was performed under the following conditions.

Resin temperature: 250°C Injection pressure: 800 kg/cm Injection time: 5 seconds Cooling time: 10 seconds The obtained sample was cut with a diamond saw, embedded in resin, and polished to determine the long axis of the permanent magnet material powder that appeared on the cross section. was measured.

As a result, the major axis of the powder of permanent magnet material in the sample is
Although the major axis was almost equal to the long axis before molding, there were chips at the edges of the powder.

Figure 6 shows an SEM photograph of the cross section of sample No. 5.
In Figure 6, about 20% of the area ratio mentioned above is observed to be fine powder with a major axis of about 10 μm or less, but this is due to the fine powder produced when the permanent magnet material powder is crushed during injection molding, and the powder. It is a fine powder that has been mixed in advance to improve the filling rate. The pre-mixed amount is 10% (number)
That's about it.

These samples were subjected to pulse magnetization at 40 kOe.

(BH)wax was measured for these samples.

The filling rate of the powder of the permanent magnet material was also measured.

The results for the compression bonded magnet are shown in Table 3, and the results for the injection bonded magnet are shown in Table 4.

As described above, even as a bonded magnet, the average crystal grain size of the main phase, the average thickness of the subphase as a grain boundary, and the A value did not show any change compared to ribbon samples No. 3.

compression bonded magnet Sample no.

injection bonded magnet Sample no.

Table (BH) wax Filling rate Permanent magnet material powder average major axis Amount of coarse powder (μm) (%) (MGOe) (%) O0 12,6 12,7 13,0 12,7 12,0 11,5 Table permanent Powder average length axis of magnet material Coarse powder amount (μm) (%) fMGOe) (BI
3rd order Filling rate (%) 7.8 6.8 8.0 6.8 7.9 7.3 From the results of the above examples, the effects of the present invention are clear.

<Effects of the Invention> According to the present invention, since a permanent magnet is manufactured by applying a high-speed quenching method, it is possible to use a non-equilibrium phase in addition to the equilibrium phase, and the R content is 5.5 or more. Even if it is less than 11.76 atomic % and isotropic, it exhibits high coercive force and high energy product, and a high-performance permanent magnet material suitable for practical use can be obtained.

For example, when R is Nd, the addition of M is about 10 atomic % N
If it is more than d, it particularly contributes to increasing the coercive force, and if it is less than about 10 atom % Nd, which allows cost reduction, it particularly contributes to improving the maximum energy product (BH) Ilax.

Furthermore, M also makes a large contribution to improving the coercive force. This tendency is not limited to Nd, but is similar when other rare earth elements are used.

The cause of the high coercive force as described above is that when the R content is within the range of the present invention, especially when it is less than 10 atomic %, the conventional R-F
Stable tetragonal RyoFe+J as seen in e-B magnets
It is thought that the cause is not a coercive force mechanism using a compound, but a microstructure with a metastable R*Fe+4B phase as a main phase in which the M element is dissolved in supersaturation by a high-speed quenching method. Normally, M is about 2 at %, it is stably dissolved as a solid solution at high temperatures, but it is impossible to form a solid solution of 2 at % or more without using a high-speed quenching method, and it is considered that it exists in a metastable state.

Therefore, the additive element M stabilizes the RtF8+J phase even at a low R composition, but this effect can only be obtained by the high-speed quenching method, and sintered magnets do not have such an effect.

Further, in the present invention, it is preferable to have not only the above-mentioned main phase but also an R-poor crystalline and/or amorphous subphase. By having such a subphase, it acts as a boundary phase for the pinning site and has the function of strengthening the bond between the main phases.

It is also easy to magnetize and has sufficient corrosion resistance.

Conventional R-T-B magnets require strict rust countermeasures because the R, T, and B phases include a B-rich phase and/or an R-rich phase that are more easily corroded than expected.

Since the permanent magnet material used in the present invention consists of a main phase consisting of R2T and 4B and a R-poor subphase, it has improved corrosion resistance and requires almost no rust countermeasures or can be used with simple treatment. It is also possible to do so.

According to the present invention, the filling rate of the powder of the permanent magnet material can be improved, so that the high characteristics of the permanent magnet material can be effectively utilized.

Furthermore, the effect of improving the filling rate is achieved not only with the composition of the present invention but also with general bonded magnets of the RTB system.

[Brief explanation of the drawing]

FIG. 1 is a ternary diagram for explaining the composition of the permanent magnet material used in the present invention. FIG. 2 is a photograph substituted for a drawing showing the crystal structure, and is a scanning electron micrograph of the permanent magnet material used in the present invention. FIG. 3 is an X-ray diffraction diagram of the permanent magnet material used in the present invention. FIG. 4 is a photograph substituted for a drawing showing the particle structure, and is a scanning electron micrograph of the permanent magnet material used in the present invention. FIG. 5 is a photograph substituted for a drawing showing the particle structure, and is a scanning electron micrograph of a cross section of a compression bonded magnet. FIG. 6 is a photograph substituted for a drawing showing the particle structure, and is a scanning electron micrograph of a cross section of an injection bonded magnet. FIG, 1 R(atshi・) FIG. e (,'i) ni■・'■ (+.

Claims (1)

[Claims] (1) R_xT_1_0_0_-_x_-_y_-_z
B_yM_z (However, R is one or more rare earth elements including Y, T is Fe or Fe and Co, and 5.5≦x
<11.76, 2≦y<15, z≦15, and M is Ti, V, Cr, Zr, Nb, M
o, Hf, Ta and W. ), and has only a main phase with a substantially tetragonal crystal structure, or has such a main phase and an amorphous and/or crystalline R-poor subphase, and has a subphase,
The value of the volume ratio of the main phase to the subphase (subphase/main phase) v is (11.
The value divided by 76-x)/x is 2 or less, and the average major axis is 20 to 300μ
1. A bonded magnet characterized in that it is formed by molding a mixture of a powder of a permanent magnet material and a binder. (2) The bonded magnet according to claim 1, wherein the powder of the permanent magnet material substantially does not contain any of powder having a major axis exceeding four times the average major axis and powder having a major axis exceeding 400 μm. (3) The bonded magnet according to claim 1 or 2, wherein the powder of the permanent magnet material is flat and has a thickness of 20 to 80 μm. (4) The bonded magnet according to any one of claims 1 to 3, wherein a value obtained by dividing the value of v by 0.1176(100-z)-x/x is smaller than 1. (5) Claims 1 to 4 comprising a main phase and a subphase, wherein the R content of the subphase is 9/10 or less of the R content of the main phase in terms of atomic ratio.
A bonded magnet as described in any of the above. (6) The bonded magnet according to any one of claims 1 to 5, wherein the binder is a thermosetting resin and the molding is performed by press molding. (7) The bonded magnet according to any one of claims 1 to 5, wherein the binder is a thermoplastic resin and the molding is performed by injection molding. (8) The bonded magnet according to any one of claims 1 to 7, wherein the permanent magnet material is a ribbon obtained by high-speed quenching. (9) Permanent magnetic material powder and binder containing at least R, T and B (wherein R is one or more rare earth elements including Y, and T is Fe or Fe and Co) A bonded magnet formed by molding a mixture of the permanent magnet material, wherein the average major axis of the powder of the permanent magnet material is 20 to 300 μm.
and the powder of this permanent magnet material has a major axis more than four times the average major axis and the major axis is 400 μm.
A bonded magnet characterized in that it contains substantially no powder exceeding .