JP2003328014A - Method for manufacturing nanocomposite magnet powder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a compound superior in filling properties, formability, and magnetic properties for a bond magnet, and to provide the bond magnet. <P>SOLUTION: The subject manufacturing method is characterized by pulverizing a quenched alloy with a pulverizing device, which alloy has the formula of (Fe<SB>1-m</SB>T<SB>m</SB>)<SB>100-x-y-z</SB>Q<SB>x</SB>R<SB>y</SB>Ti<SB>z</SB>M<SB>n</SB>, (wherein T indicates one or more elements selected from the group consisting of Co and Ni; Q indicates one or more elements selected from the group consisting of B and C but surely containing B; R indicates one or more rare earth metallic elements substantially excluding La and Ce; and M indicates at least one metallic element selected from the group consisting of Al, Si, V, Cr, Mn, Cu, Zn, Ga, Zr, Nb, Mo, Hf, Ta, W, Pt, Pb, Au, and Ag), and has such composition ratios (x), (y), (z), (n), and (m) as to respectively satisfy 10<x≤20 atom.%, 6≤y<10 atom.%, 0.1≤z≤12 atom.%, 0≤n≤10 atom.%, and 0≤m≤0.5. Then, the manufactured alloy powder has particle size distribution having a first peak of grain sizes in more than 106 μm but 300 μm or less and a second peak in 106 μm or less. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a rare earth alloy powder for bonded magnets, a compound for bonded magnets, and a bonded magnet using the same.

[0002]

2. Description of the Related Art At present, bond magnets are used in various electric devices such as motors, actuators, speakers, meters, focus convergence rings and the like. The bonded magnet is a magnet manufactured by mixing alloy powder for magnet (magnet powder) and a binder (resin or low melting point metal), and molding and solidifying the mixture.

Conventionally, Ma has been used as a magnetic powder for bonded magnets.
Fe-RB magnet powder sold by gnequench International (hereinafter abbreviated as "MQI"),
So-called MQ powder is widely used. MQ powder is generally Fe _100-ab B _a R _b (Fe is iron, B is boron, R is
Pr, Nd, Dy, and at least one kind of rare earth element selected from the group consisting of Tb), and a and b in the composition formula are 1 atomic% ≤ a ≤ 6 atomic%,
And the content of 10 atomic% ≤ b ≤ 25 atomic% are satisfied, and the R content b is high.

Conventional alloy powders for bonded magnets represented by MQ powders are produced by rapidly solidifying molten raw material alloys (that is, "molten alloy melt"). As the liquid quenching method (melt quenching method), a melt spinning method (typically a single roll method) is often used. The single roll method is a method in which the molten alloy is cooled and solidified by bringing the molten alloy into contact with a rotating cooling roll. In the case of this method, the shape of the quenched alloy extends in a ribbon shape along the surface circumferential velocity direction of the cooling roll. The quenched alloy ribbon thus produced is heat-treated and then pulverized to have an average particle size of 300 μm or less (typically about 150 μm) to obtain a rare earth alloy powder for a permanent magnet. Below, the above-mentioned rare earth alloy powder produced by the liquid quenching method will be simply referred to as "conventional quenching magnet powder" and will not include the nanocomposite magnet powder described below.

[0005] Conventional quenching magnet powder and resin (here, containing rubber or elastomer) are mixed,
A compound for bonded magnets (hereinafter, simply referred to as "compound") is prepared. In this compound,
Additives such as lubricants and coupling agents may be mixed.

This compound is molded into a desired shape by, for example, compression molding, extrusion molding or injection molding to obtain a bonded magnet as a molded body of permanent magnet (also referred to as "permanent magnet body"). Further, since the bonded magnet produced by compression molding or extrusion molding has a low binder content, it may be further surface-treated in order to protect the magnet powder from corrosion.

On the other hand, in recent years, nano-composite magnets of iron-based rare earth alloys (especially Fe—R—B type) (referred to as “exchange spring magnets”) have been used as magnet powders used for bonded magnets because of their relatively low cost. It is sometimes used.) Powder is being used. The Fe-RB-based nanocomposite magnet is, for example, Fe ₃ B or Fe ₂₃ B ₆ or the like, which is a soft magnetic phase of microcrystals of iron-based boride and R ₂ which is a hard magnetic phase.
This is an iron-based alloy permanent magnet in which Fe ₁₄ B phase microcrystals are uniformly distributed in the same metallic structure, and both are magnetically coupled by exchange interaction (for example, Japanese Patent Application No. 11-362103 by the applicant of the present application). No. and Japanese Patent Application 2000-371
788).

The nanocomposite magnet exhibits excellent magnetic characteristics by including magnetic coupling (exchange interaction) between the soft magnetic phase and the hard magnetic phase even though it contains the soft magnetic phase. Further, as a result of the presence of the soft magnetic phase containing no rare earth element R such as Nd, the content of the rare earth element R can be suppressed low as a whole (typically, the content ratio of R is 4.5 atom%). This is advantageous in reducing the manufacturing cost of the magnet and stably supplying the magnet. Further, since the content ratio of R active to oxygen is low, it is also excellent in corrosion resistance. In addition,
This nanocomposite magnet is also produced by the liquid quenching method. This nanocomposite magnet is pulverized by a predetermined method to obtain nanocomposite magnet powder.

The magnetic characteristics of the bonded magnet depend on the magnetic characteristics of the magnet powder contained in the bonded magnet and the filling rate thereof. Therefore, in order to improve the magnetic characteristics of the bonded magnet, it has been studied to improve the filling rate of the magnet powder.

Further, in recent years, with the miniaturization and higher performance of electric equipment, the demand for small and high-performance magnets has been increasing more and more. For example, a ring magnet for a spindle motor has an outer diameter of 15 mm to 20 mm and an inner diameter of 13 mm.
.About.18 mm, thickness of about 1 mm to 2 mm, or as a ring magnet for a stepping motor, a product having an outer diameter of 4 mm to 10 mm, an inner diameter of 2 mm to 8 mm, and a thickness of about 0.5 mm to 1.5 mm. Demand is increasing.

[0011]

However, as a result of the study by the present inventors, it was found that the above-mentioned conventional quenched magnet powder and conventional nanocomposite magnet powder have the following problems.

Conventional quenched magnet powders represented by MQ powders typically have a roll surface peripheral velocity of 18 m / sec or more and a thickness of 50 μm or less (typically about 20 μm to about 4 μm).
It is manufactured by producing a quenched alloy ribbon of 0 μm), heat-treating the quenched alloy ribbon, and then pulverizing the quenched alloy ribbon to an average particle diameter of 300 μm or less (typically about 150 μm). The magnet powder thus produced has a flat particle shape, and the powder particle has an aspect ratio of less than 0.3. The aspect ratio represents the size in the minor axis direction / the size in the major axis direction.

Although this magnet powder has excellent magnetic properties, the packing ratio of the magnet powder (density of bonded magnet / density of powder particles) is the highest among the various molding methods. Even with the compression molding method used, the maximum is usually about 80%.

For example, when a conventional quenched magnet powder is used and a bonded magnet having a packing ratio of the magnet powder of more than 80% is molded by a compression molding method, the amount of resin entering the gap between the magnet powders is reduced, so that the porosity is reduced. , And the magnetic particles may shed. As a result, the magnetic characteristics are significantly deteriorated by the oxidation under the use environment. In order to prevent this deterioration of magnetic properties, voids are filled (sometimes called "sealing treatment") or a protective film of sufficient thickness is formed on the surface (surface treatment) in a later step. Need to do. Also, forming a thick protective film such as resin by surface treatment means increasing the thickness of the non-magnetic layer on the surface of the magnet, which widens the magnetic gap in the magnetic circuit and lowers the utilization efficiency of magnetic energy. I will let you. Further, in the process of producing and molding the compound, particles of the magnet powder may be destroyed and a new surface may be exposed, resulting in a decrease in corrosion resistance and a decrease in magnetic property due to surface oxidation.

In order to improve the filling rate by using the conventional quenched magnet powder, an attempt has been made to control the particle size distribution of the quenched magnet powder, as disclosed in, for example, Japanese Patent Application Laid-Open No. 63-155601. However, there is a problem that a sufficient filling rate cannot be realized and the particle size needs to be adjusted, resulting in an increase in process cost.

Further, as a result of the study by the present inventors, the conventional rapidly quenched magnet powder is easily oxidized due to the high content of rare earth elements, and the smaller the particle size, the greater the degree of deterioration of the magnetic properties due to the oxidation ( For example, in the case of MQP-B (maximum particle size of 300 μm or less), the residual magnetic flux density B _r (0.79T) of powder particles of 53 μm or less is more than 106 μm 12
Residual magnetic flux density B _r of powder particles of 5 μm or less (0.90
It is less than 90% of T). ), The magnetic properties of the magnet powder itself deteriorate as the fraction of small particles increases. In order to suppress the deterioration of magnetic properties due to this oxidation, it is necessary to suppress the fraction of small particles contained in the magnet powder for bonded magnets, and as a result, the particle size distribution adjustment to improve the packing rate is required. There was also a limit.

Further, since the conventional quenched magnet powder contains a lot of particles having a relatively large particle size, it is difficult to mold a small magnet, which is in high demand in recent years, and the large particles are likely to be shed. is there.

In order to improve the moldability (particularly the fluidity) of the conventional quenched magnet powder, Japanese Patent Laid-Open No. 315174/1993 proposes a method using magnet powder produced by the gas atomizing method. According to the above-mentioned publication, the particles of the magnet powder produced by the gas atomization method are close to granular (spherical), so that the fluidity can be improved by adding this magnet powder to the conventional quenched magnet powder. However, since the gas atomization method has a slower cooling rate than the liquid quenching method described above, it is difficult to produce magnet powder exhibiting sufficient magnetic properties with a conventional composition, and it is said that the method is industrially applicable. hard.

On the other hand, the conventional Fe-R-B based nanocomposite magnet powder has a relatively low content of rare earth elements,
The volume ratio of the hard magnetic phase is typically 30% or less. Therefore, the magnetic properties (for example, coercive force H _cJ ) are lower than those of conventional quenching magnet powders (MQ powders, etc.), so that there is a problem that a bond magnet having sufficient magnetic properties cannot be obtained. For example, a hard disk drive device (HDD) ) Motor could not be applied.

The present invention has been made in view of the above points, and its main purpose is to provide a method for producing a nanocomposite magnet powder having excellent filling properties and / or moldability and magnetic properties. is there.

[0021]

A method for producing a nanocomposite magnet powder according to the present invention has a composition formula of (Fe _1-m T _m ).
_{100-xyz Q x R y Ti} z M n (T is at least one element selected from the group consisting of Co and Ni, Q is at least one element always including the B is selected from the group consisting of B and C , R
Is one or more rare earth metal elements substantially free of La and Ce, M is Al, Si, V, Cr, Mn, Cu, Z
n, Ga, Zr, Nb, Mo, Hf, Ta, W, Pt,
At least one metal element selected from the group consisting of Pb, Au, and Ag), and the composition ratios x, y,
z, n and m are respectively 10 <x ≦ 20 atomic%,
6 ≦ y <10 atomic%, 0.1 ≦ z ≦ 12 atomic%, 0 ≦ n
A step of preparing a quenched alloy satisfying ≦ 10 atomic% and 0 ≦ m ≦ 0.5 and having an average thickness of more than 40 μm and 90 μm or less, a rotating crushing part, and a plurality of parts arranged on the outer periphery of the crushing part. The crushing step of crushing the quenched alloy by using a crushing device equipped with a screen having an opening of (1) to produce an alloy powder having a particle size smaller than that of the opening of the screen.

In a preferred embodiment, in the crushing step, the first particle size is in the range of more than 106 μm and 300 μm or less.
An alloy powder having a particle size distribution having a peak and a second peak in a particle size range of 106 μm or less is prepared.

In a preferred embodiment, the step of preparing the quenched alloy includes the step of preparing a molten alloy of the alloy represented by the composition formula, and 1.5 kg / min of the molten alloy on the surface of a rotating cooling roll. And a cooling step of producing a quenched alloy containing R ₂ T ₁₄ Q type compound crystal grains in a volume ratio of 50% or more of the total volume.

In a preferred embodiment, the magnetically coupled R ₂ T ₁₄ Q type compound and the ferromagnetic iron-based boride are contained, and the volume ratio of the total crystalline phase is 95% of the total.
Above, and the volume ratio of the amorphous phase is 5% or less of the whole.

In a preferred embodiment, said R ₂ T ₁₄
The volume ratio of the Q-type compound is 65% or more and 85% or less of the whole.

In a preferred embodiment, the ferromagnetic iron-based boride is present at a grain boundary of the R ₂ T ₁₄ Q type compound.

In a preferred embodiment, said R ₂ T ₁₄
The Q-type compound has an average crystal grain size of 10 nm to 200 nm, and the ferromagnetic iron-based boride has an average crystal grain size of 1 nm to 100 nm.

In a preferred embodiment, before the step of producing the alloy powder, a step of producing coarsely pulverized powder having an average size of 1 mm or less by roughly pulverizing the quenched alloy is included.

In a preferred embodiment, after the step of producing the coarsely pulverized powder, a heat treatment step of heating the coarsely pulverized powder of the quenched alloy or the alloy powder at a temperature of 500 ° C. or higher and 900 ° C. for 10 seconds or longer is further included.

In a preferred embodiment, the crushing device is a power mill or a feather mill in which the size of the opening of the screen is set in the range of more than 200 μm and 1.0 mm or less.

The method for producing a bonded magnet according to the present invention comprises the steps of preparing the nanocomposite magnet powder produced by the above method and compression molding the nanocomposite magnet powder to obtain a density of 6.0 g / cm ³ or more. And a step of producing a molded body having.

[0032]

BEST MODE FOR CARRYING OUT THE INVENTION The inventors of the present invention have added a proper amount of Ti to a rare earth alloy having a specific composition and rapidly solidify the molten alloy under predetermined conditions to rapidly solidify the alloy, thereby providing a nanocomposite quenched alloy for magnets. It was found that the above can be produced, and disclosed in Japanese Patent No. 3264664. Then, the present inventor produced this quenched alloy for nanocomposite magnet under the condition that the average thickness thereof is adjusted within a predetermined range, and then pulverized it with a specific pulverizing device to obtain 6.0 g / cm ³ The present inventors have found that a pulverized powder having a particle size distribution excellent in moldability and capable of achieving the above-mentioned high molding density can be obtained, and have arrived at the present invention. According to the present invention, it is possible to obtain a nanocomposite magnet powder having an optimum particle size distribution for compression molding without newly adding a particle size distribution adjusting step after the crushing step.

In the present invention, first, the composition formula is (Fe
_1-m T m) are expressed in _{100-xyz Q x R y Ti} z M n, an average thickness of 40μm ultra 90μm or less, the standard deviation of the thickness of 15μ
Prepare a quenched alloy of m or less. Here, T is at least one element selected from the group consisting of Co and Ni, and Q is B.
And at least one element selected from the group consisting of C and always containing B, R is at least one rare earth metal element substantially not containing La and Ce, M is Al, Si, V, Cr, M
n, Cu, Zn, Ga, Zr, Nb, Mo, Hf, T
It is at least one metal element selected from the group consisting of a, W, Pt, Pb, Au and Ag, and the composition ratios x, y, z, n and m are 10 <x ≦ 20, respectively.
%, 6 ≦ y <10 atomic%, 0.1 ≦ z ≦ 12 atomic%, 0 ≦ n ≦ 10 atomic%, and 0 ≦ m ≦ 0.5.

Such a quenched alloy is preferably prepared by a step of preparing a melt of the alloy having the above composition, and contacting the surface of the rotating cooling roll with the melt of the alloy at a supply rate of 1.5 kg / min or more. And thereby R ₂ T ₁₄ Q
And a cooling step of producing a quenched alloy in which the volume ratio of the type compound crystal grains is larger than the volume ratio of the α-Fe phase.

The quenched alloy produced by the above method has a volume ratio of R ₂ T ₁₄ of 50% or more immediately after rapid solidification.
Although it contains a Q-type compound, it also contains an amorphous phase, so it is preferable to perform heat treatment for crystallization. The quenched alloy immediately after quenching, or after heat treatment if necessary, contains a magnetically bound R ₂ T ₁₄ Q-type compound and a ferromagnetic iron-based boride, and forms a nanocomposite structure. ing. In a preferred embodiment, the volume ratio of all crystalline phases in the alloy is 95% or more of the whole,
Moreover, the volume ratio of the amorphous phase is 5% or less of the whole. In particular, the volume ratio of the R ₂ T ₁₄ Q type compound responsible for hard magnetism is preferably 65% or more and 85% or less of the whole.

The ferromagnetic iron-based boride contained in such a nanocomposite magnet alloy exists at the grain boundary of the R ₂ T ₁₄ Q type compound, and in a preferred embodiment, R ₂ T ₁₄ Q.
Type compound has an average crystal grain size of 10 nm to 200 nm, and ferromagnetic iron-based boride has an average crystal grain size of 1 nm to 10 nm.
It is within the range of 0 nm or less.

The above-mentioned nanocomposite magnet powder has a structural structure obtained by adding an appropriate amount of Ti, and hence it is hereinafter referred to as "Ti-containing nanocomposite magnetic powder". Since this Ti-containing nanocomposite magnetic powder has the composition and structure as described above, the hard magnetic phase and the soft magnetic phase are magnetically coupled by the exchange interaction, and the content ratio of the rare earth element is compared. Despite its relatively low magnetic properties, it has magnetic properties equal to or better than those of conventional quenched magnet powders, and more excellent magnetic properties than conventional nanocomposite magnet powders containing Fe ₃ B phase as the main phase. (Especially high coercive force H _cJ ). Specifically, the Ti-containing nanocomposite magnetic powder according to the present invention comprises:
Maximum energy product (BH) max: 70 kJ / m ³ or more, coercive force H _cJ : 700 kA / m or more, residual magnetic flux density B
_r : 0.7 T or more can be realized, and further, maximum energy product (BH) max: 90 kJ / m ³ or more, coercive force H _cJ : 800 kA / m or more, residual magnetic flux density B _r : 0.8
T or more can be realized.

As described above, since the nanocomposite magnetic powder produced by the manufacturing method of the present invention has magnetic characteristics equal to or higher than those of the conventional quenching magnet powder, the nanocomposite magnetic powder of the conventional quenching magnet powder (for example, MQ powder) is used. Instead, it can be used as a magnetic powder for a bonded magnet. Of course, as magnetic powder for bonded magnets, T
Although it is preferable to use only the i-containing nanocomposite magnetic powder, conventional quenching magnet powder or the like may be mixed to the extent that the characteristics of the Ti-containing nanocomposite magnetic powder are not impaired.

Further, since the Ti-containing nanocomposite magnetic powder has the above-mentioned composition and structure, it has a characteristic that its magnetic characteristics have little particle size dependence. For example, the residual magnetic flux density B _r of particles of 53 μm or less is 106 μm.
Particles having a residual magnetic flux density B _{r of} more than m and not more than 250 μm can be obtained (95% or more). The Ti-containing nanocomposite magnetic powder has a relatively low content of the rare earth element R, and has a small boride phase dispersed so as to surround the R ₂ Fe ₁₄ B phase, and Ti has a high affinity with boron. Therefore, the boride phase contains more Ti than the other phases.
As a result, the Ti-containing nanocomposite magnetic powder is superior in oxidation resistance to the conventional quenched magnet powder. in this way,
Since the conventional quenched magnet powder contains a relatively large amount of rare earth element R, it is easily oxidized, and the smaller the particle size, the more marked the deterioration of the magnetic properties due to the oxidation of the powder particle surface.
The contained nanocomposite magnetic powder has little deterioration in magnetic properties due to oxidation, and has little dependence on the particle size of magnetic properties.

In the present invention, the crushing apparatus shown in FIGS. 1 (a) and 1 (b) is used to crush the above-mentioned quenched alloy. This crushing device is a crushing device called a power mill or a feather mill, and has a rotating crushing unit (crushing blade) 10
0, and a screen 102 having a plurality of openings arranged on the outer periphery of the crushing unit 100. The screen 102 has a cylindrical shape (for example, 200 mmφ x 170 m high)
m), and a large number of openings are formed in substantially the entire screen 102. The arrangement pattern of the openings in the screen 10 is arbitrary, and the size or shape of the openings may change along the height direction of the screen 102. The size of the opening is, for example, 200 to 700 μm.
Is in the range. The screen 102 is not limited to the round hole screen as shown, but may be a square hole screen, a mesh screen, a herringbone screen, or the like.

The crushing blade 100 is composed of a plurality of hard blades radially projecting around a rotation axis and arranged in a plurality of stages along the rotation axis.
It can rotate at a speed of 000-4000 rpm.

The quenching alloy (grinding raw material) to be crushed for the crushing device in which the crushing blade 100 is rotating.
Is thrown in from above. The quenched alloy that has been thrown violently collides with the crushing blade 100 and also collides with the inner peripheral surface of the screen 102. The quenched alloy crushed to a size larger than the opening formed in the screen 102 cannot be ejected to the outside of the screen 102, and is further crushed by the crushing blade 100. On the other hand, the quenched alloy crushed to be smaller than the opening of the screen 102 can be ejected to the outside of the screen 102 through the opening. A screen cover (not shown) is provided on the outer peripheral portion of the screen 102 to facilitate the collection of the powder jumping out from the opening of the screen 102. After the crushing step is finished, the crushed powder collected from both the outside and the inside of the screen 102 eventually constitutes the powder, and the raw material recovery rate reaches about 100%.

When the above-mentioned quenched alloy is crushed using such a crushing device, generally, a powder having a relatively wide particle size distribution is produced. However, when a quenched alloy having a specific structure and used in the present invention and having a specific thickness is crushed by the above crushing device, the particle size has a first peak in a range of more than 106 μm and 300 μm or less, and , Particle size is 106μm
An alloy powder having a particle size distribution having the second peak in the following range can be produced. With such a bimodal particle size distribution having two peaks, a powder having a relatively small particle size is formed in a gap formed by powder particles having a relatively large particle size (particle size: more than 106 μm). Because particles get in,
It has excellent filling properties and can greatly improve the molding density.

It is preferable that powder particles having a particle size of more than 106 μm account for 50% or more of the total weight ratio. In the present invention, the average thickness of the quenched alloy to be crushed is more than 40 μm and 90
It is in the range of μm or less and is thicker than the conventional quenched alloy, so that the powder particles having a particle size of more than 106 μm are not flat but have an equiaxed shape. In a preferred embodiment,
The aspect ratio of powder particles having a particle size of more than 106 μm is 0.3.
It is in the range of 1.0 to 1.0. By combining such relatively large and equiaxed powder particles with powder particles of a size that fits properly in the gap,
The nanocomposite magnet powder of the present invention is made up.

As described above, the average thickness of the quenched alloy has a strong influence on the shape of the powder particles (equal axis or flattening), but simply using an alloy material containing no Ti, the average thickness of When a thick-quenched alloy is to be produced, α-Fe and the like are precipitated, and the final magnet characteristics are greatly deteriorated. The effect of adding Ti will be described later in detail.

How to set the thickness of the quenched alloy is controlled by the rate at which the molten metal is supplied to the cooling roll and the peripheral speed of the surface of the cooling roll. Therefore, the cooling rate of the molten metal is determined by the set value of the thickness. This cooling rate affects the microstructure of the alloy. Therefore, if the thickness varies depending on the portion of the quenched alloy, portions with different cooling rates exist in the alloy, the uniformity of the structure deteriorates, and α-Fe precipitates in the insufficient quenching portion. Will be done. Since precipitation and coarsening of α-Fe deteriorates the magnetic properties of the nanocomposite magnet of the present invention, it is desirable to control the thickness of the quenched alloy uniformly. Therefore, in the preferred embodiment of the present invention, the standard deviation of the thickness of the quenched alloy is controlled to 15 μm or less. A preferred value of the standard deviation of thickness is 13 μm or less, and a more preferred value is 11 μm or less.

In the present invention, the quenched alloy having the above-mentioned composition and structure is pulverized by using a pulverizing apparatus as shown in FIG. 1 to obtain a nanocomposite magnet powder having a desired particle size distribution immediately after pulverization. You can However, when crushing with a pin mill instead of the above crushing device, the beak position of the particle size distribution is relatively easy to adjust, but the width of the particle size distribution cannot be adjusted. For example, if the peak position of the particle size distribution is shifted to the side where the particle size increases, the pulverization step is performed under the condition that the average particle size increases, and the powder recovery rate will decrease significantly.
Therefore, powder particles with a large particle size (particle size: more than 106 μm)
It is difficult to increase the weight ratio occupied by.

On the other hand, according to the crushing device of the type used in the present invention, it is possible to easily increase the proportion of powder particles having a large particle diameter by increasing the size of the opening provided in the screen. Moreover, the recovery rate is about 1
It is 00%. Further, in the case of the quenched alloy used in the present invention,
Not only are the powder particles appropriately sized to fit into the gaps between the powder particles having a relatively large particle size, but also the relatively small powder particles have excellent magnetic properties. This is also considered to be due to the effect of adding Ti.

The maximum particle size of the Ti-containing nanocomposite magnetic powder is preferably 300 μm or less, and more preferably 250 μm or less, in order to suppress shedding and the like in a small magnet. Furthermore, it is preferable to adjust the average particle size of the powder particles to be in the range of more than 53 μm and 125 μm or less. The Ti-containing nanocomposite magnetic powder having such a particle size distribution is suitably used for manufacturing the above-mentioned particularly small ring magnet.

The particle size in the present specification is JIS
It shall be determined by sorting with a standard sieve of 8801. Further, the minimum particle size of the particles contained in the Ti-containing nanocomposite magnetic powder is not particularly limited, but in the manufacturing process of the Ti-containing nanocomposite magnetic powder, ultrafine powder particles having a particle size of 1 μm or less are easily removed, and , Preferably removed.

By adjusting the particle size distribution of the Ti-containing nanocomposite magnetic powder according to the present invention so that the particle size has a second peak in the range of 53 μm or less, the formability can be further improved. This is because a relatively small particle forming the second peak is formed in a gap formed by relatively large particles forming the first peak (particles having a particle size of more than 106 μm are also referred to as “first particles”). It is considered that particles (particles having a particle size of 53 μm or less are sometimes referred to as “second particles”) are efficiently filled.

The effect of improving the formability by this particle size distribution is that the aspect ratio (minor axis / major axis) of the first particles is 0.3.
It is remarkably obtained when it is 1.0 or more. That is, even if the sizes of the first particles and the second particles are controlled, if the aspect ratio of the first particles (particles having a particle size of more than 106 μm) is less than 0.3, the gap formed by the first particles Is considered to be a flat shape and it becomes difficult for the second particles to be filled in the gaps. Of course, the aspect ratio of the second particles is also preferably 0.3 or more and 1.0 or less. Since the second particles have a smaller particle size than the first particles,
It is easy to make the aspect ratio of the particles equal to or higher than the aspect ratio of the first particles.

As will be described below, the Ti-containing nanocomposite magnetic powder of the present invention uses the strip casting method to produce particles having an aspect ratio of 0.3 or more, or 0.4 or more with high productivity. be able to. For details of the method for producing the Ti-containing nanocomposite magnetic powder using the strip casting method, see, for example, Japanese Patent Application No.
No. 001-342692.

The Ti-containing nanocomposite magnetic powder used in the magnetic powder for a bonded magnet according to the present invention has a slower cooling rate (10 ² to 10 ⁶ ° C / ° C) than that of the conventional quenched magnet powder due to the function of Ti, as will be described later in detail. It can also be produced by cooling the molten alloy in seconds), so that the above metallographic structure can be obtained even if an alloy having a plate thickness thicker than the conventional one is produced using the strip casting method. The quenched alloy of the Ti-containing nanocomposite used in the present invention is composed of fine crystal grains, so that it easily breaks along a random orientation, and is equiaxial (aspect ratio of 0.3 or more). Powder particles (close to 1) are likely to be generated.

Since the length of the minor axis of particles having a particle size larger than the thickness of the alloy ribbon obtained by crushing the alloy ribbon of the quenched alloy is determined by the thickness of the alloy ribbon, the thickness of the alloy ribbon is large. The particles having a larger aspect ratio (closer to 1) can be obtained by crushing. Therefore, the average thickness of particles having a particle size of more than 106 μm corresponds to the length of the short axis, falls within the range of more than 50 μm and 120 μm or less, and has an aspect ratio of 0.4 or more and 1.0 or more.
The following particles are obtained.

Further, since the quenched alloy of Ti-containing nanocomposite is easily broken at random as described above,
The smaller the particle size, the larger the aspect ratio tends to be, and the particles whose particle size is equal to or less than the thickness of the alloy ribbon,
It has a larger aspect ratio.

According to the present invention, even if the Ti-containing nanocomposite magnetic powder produced by the above method is not classified after the pulverizing step to adjust the particle size distribution, a bimodal particle size suitable for molding and compression is obtained. The distribution is obtained.

The Ti-containing nanocomposite magnetic powder produced by the method as described above mainly has an aspect ratio of 0.
Since it is composed of 4 to 1.0 powder particles,
The filling property is excellent as compared with the conventional quenched magnet powder having an aspect ratio of less than 0.3. Therefore, the aspect ratio is 0.4
By preparing the compound using the Ti-containing nanocomposite magnetic powder of 1.0 or less, as compared with the case of using the conventional quenched magnet powder, the magnetic properties are not deteriorated and the filling property and the moldability are excellent. You can get a compound.

Particles having an aspect ratio of 0.3 or more, especially,
Particles having an aspect ratio of 0.4 or more can remarkably obtain the effect of improving the formability by adjusting the particle size distribution as described above, and also have the effect of suppressing springback during forming. As a result, a bonded magnet having a high filling rate (low porosity) can be obtained. When a thermosetting resin is used as the resin and is molded by, for example, a compression molding method, a bonded magnet having a magnetic powder filling rate of 80% or more can be obtained.

A compound for a bonded magnet can be obtained by mixing (and / or kneading) the magnetic powder containing the Ti-containing nanocomposite magnetic powder according to the present invention with various resins by a known method. As the resin, a known thermosetting resin or thermoplastic resin can be used. Furthermore, since the Ti-containing nanocomposite magnetic powder according to the present invention improves the moldability of the compound, it is possible to use a high-viscosity resin that has been difficult to use in the past. Furthermore, when the Ti-containing nanocomposite magnetic powder according to the present invention is used, the deterioration of the magnetic properties due to oxidation is small, so that the resin having a high melting point or softening point or curing temperature, which is conventionally difficult to use (for example, polyimide or heat-resistant grade product). Can be used, the characteristics (heat resistance, etc.) of the bonded magnet can be improved.

By using the Ti-containing nanocomposite magnetic powder according to the present invention, as described above, it is possible to provide a bonded magnet having a low porosity (void ratio) while ensuring a filling rate equal to or higher than the conventional one. . Therefore, it is possible to suppress / prevent various problems such as a decrease in reliability that accompanies the surface treatment of the as-molded bonded magnet having many voids. In addition,
The surface treatment in the present specification is a sealing treatment for filling voids,
Known surface treatment methods can be widely used, including formation of a protective film on the surface or modification of the surface.

As described above, according to the present invention, in addition to the bonded magnet having a low porosity being obtained, the corrosion resistance of the magnetic powder itself is higher than that of the conventional quenched magnet powder (for example, MQ powder). This is because the rare earth element content in the magnetic powder is lower than that of the conventional quenched magnet powder, and it has the above-mentioned structure. Therefore, as compared with the conventional bonded magnet using the rapidly cooled magnet powder, a bonded magnet having extremely high corrosion resistance can be obtained.

Further, according to the present invention, a bonded magnet having a high corrosion resistance of the magnetic powder itself and a low porosity can be obtained.
Sufficient corrosion resistance can be obtained by simpler surface treatment than before. That is, by simplifying the surface treatment process without sacrificing the corrosion resistance,
It is possible to improve production efficiency and reduce costs. Of course, the bonded magnet having a low porosity also has an advantage that it has excellent mechanical strength as compared with the conventional bonded magnet having a relatively high porosity.

Further, even if the thickness of the protective film formed on the surface of the bonded magnet is thinner than the conventional one, mechanical strength and / or corrosion resistance equal to or higher than the conventional one can be obtained.
Therefore, it is possible to reduce the thickness of the non-magnetic layer such as the resin coating formed on the surface of the magnet as compared with the conventional one, and to suppress the decrease in the utilization efficiency of the magnetic energy due to the magnetic gap formed in the magnetic circuit. .

The magnetic powder for a bonded magnet, the compound using the same and the bonded magnet according to the present invention will be described in more detail below.

[Ti-Containing Nanocomposite Magnetic Powder] The Ti-containing nanocomposite magnetic powder of the present invention comprises Ti-containing F.
The molten alloy of the e-R-B type alloy is cooled to form a rapidly solidified alloy. This rapidly solidified alloy is
Although it contains a crystalline phase, it is heated if necessary to further promote crystallization.

By adding Ti to an iron-based rare earth alloy having a composition within a specific range, the present inventor is likely to generate excellent magnetic properties (especially high coercive force and excellent demagnetization curve) during the cooling process of the molten alloy. R, which suppresses the precipitation and growth of the α-Fe phase that causes the obstruction of the expression of (squareness) and bears the hard magnetic property.
It was found that the crystal growth of the ₂ Fe ₁₄ B type compound phase can be preferentially and uniformly advanced.

When Ti was not added, Nd ₂ Fe ₁₄
The α-Fe phase precipitates prior to the precipitation / growth of the B phase, which facilitates the growth. Therefore, at the stage when the crystal heat treatment for the quenched alloy is completed, the soft magnetic α-Fe phase is coarsened and the squareness of the demagnetization curve is deteriorated.
_max is greatly reduced.

On the other hand, when Ti is added, α-
Since the kinetics of precipitation / growth of the Fe phase becomes slow and the precipitation / growth requires time, if the precipitation / growth of the Nd ₂ Fe ₁₄ B phase starts before the precipitation / growth of the α-Fe phase is completed. Conceivable. Therefore, the Nd ₂ Fe ₁₄ B phase grows large in a state in which it is uniformly dispersed before the α-Fe phase becomes coarse. Also, Ti has a strong affinity for B,
It seems to be easily concentrated in iron-based borides. It is believed that the addition of Ti stabilizes the iron-based boride due to the strong bonding of Ti and B within the iron-based boride.

According to the present invention, the soft magnetic phases such as the iron-based boride and the α-Fe phase are made fine by the action of Ti, the Nd ₂ Fe ₁₄ B phase is uniformly dispersed, and the Nd ₂ Fe phase is further dispersed.
It is possible to obtain a nanocomposite structure having a high volume ratio of ₁₄ B phase. As a result, the coercive force and the magnetization (residual magnetic flux density) are increased and the squareness of the demagnetization curve is improved as compared with the case where Ti is not added.

Hereinafter, the Ti-containing nanocomposite magnetic powder according to the present invention will be described in more detail.

The Ti-containing nanocomposite magnetic powder according to the present invention preferably has a composition formula of (Fe _{1 -m} T _m ).
It is expressed by _100-xyz Q _x R _y M _z . Here, T is one or more elements selected from the group consisting of Co and Ni, and Q
Is one or more elements selected from the group consisting of B (boron) or B and C (carbon), R is one or more rare earth elements substantially free of La and Ce, M is Ti, Zr,
And Hf, which is at least one metal element selected from the group consisting of Hf and Hf, and always contains Ti.

X, y, z, and m which define the composition ratio
Are 10 <x ≦ 20 atomic%, 6 <y <10 atomic%, 0.1 ≦ z ≦ 12 atomic%, and 0 ≦ m ≦ 0.5, respectively.
It is preferable to satisfy the relationship.

The Ti-containing nanocomposite magnetic powder has a magnetization (residual magnetic flux density) of T due to the addition of Ti, even though the composition ratio of the rare earth element is less than 10 atomic% of the whole.
An unexpected effect of maintaining or increasing the level equivalent to the case where i is not added and improving the squareness of the demagnetization curve is exhibited.

In the Ti-containing nanocomposite magnetic powder, since the size of the soft magnetic phase is minute, the constituent phases are combined by exchange interaction, and in addition to the hard magnetic R ₂ Fe ₁₄ B type compound phase, iron-based borides and Even if a soft magnetic phase such as α-Fe is present, the alloy as a whole can exhibit excellent squareness of the demagnetization curve.

The Ti-containing nanocomposite magnetic powder is preferably an iron-based boride or α-having a saturation magnetization equal to or higher than the saturation magnetization of the R ₂ Fe ₁₄ B type compound phase.
It contains Fe. This iron-based boride is, for example, Fe
₃ B (saturation magnetization 1.5T) and Fe ₂₃ B ₆ (saturation magnetization 1.6
T). Here, the saturation magnetization of the R ₂ Fe ₁₄ B type compound is about 1.6 T when R is Nd, and the saturation magnetization of α-Fe is 2.1 T.

Usually, the composition ratio x of B exceeds 10 atomic%, and the composition ratio y of the rare earth element R is 5 atomic% or more 8
When it is in the range of atomic% or less, R ₂ Fe ₂₃ B ₃ is produced, but even when a raw material alloy having such a composition range is used, by adding Ti as in the present invention, Instead of the R ₂ Fe ₂₃ B ₃ phase, an R ₂ Fe ₁₄ B phase and an iron-based boride phase such as the Fe ₂₃ B ₆ phase or the Fe ₃ B phase can be generated. That is, by adding Ti, the ratio of the R ₂ Fe ₁₄ B phase can be increased, and the generated iron-based boride phase contributes to the improvement of the magnetization.

According to the experiments of the present inventor, only when Ti is added, unlike the case where other kinds of metals such as V, Cr, Mn, Nb, and Mo are added, there is no decrease in magnetization.
Rather, it was discovered for the first time that the magnetization improved. Also, T
When i was added, the squareness of the demagnetization curve was particularly good as compared with the other additive elements described above.

The effect of adding Ti is that B is 1
It is remarkably exhibited when it exceeds 0 atom%. Below, FIG.
This point will be explained with reference to.

FIG. 2 shows Nd-F to which Ti is not added.
It is a graph which shows the maximum magnetic energy product (BH) _{max of an} e-B magnet alloy, and the relationship of B amount. In the graph, a white bar shows data of a sample containing 10 atomic% or more and 14 atomic% or less Nd, and a black bar shows data of a sample containing 8 atomic% or more and less than 10 atomic% Nd. On the other hand, FIG. 3 is a graph showing the relationship between the maximum magnetic energy product (BH) _max and B of the Nd-Fe-B magnet alloy containing Ti. In the graph, a white bar shows data of a sample containing 10 atomic% or more and 14 atomic% or less Nd, and a black bar shows data of a sample containing 8 atomic% or more and less than 10 atomic% Nd.

As can be seen from FIG. 2, when Ti is added,
In the sample without B, B was 10 regardless of the Nd content.
Maximum magnetic energy product as the number exceeds atomic%
(BH)_maxIs falling. Furthermore, the extent of this decline
Is larger when the Nd content is 8 to 10 atomic%.
Become. This tendency has been known from the past, and Nd ₂
Fe₁₄In a magnet alloy whose main phase is B phase, the amount of B is
It is thought that it is preferable to set it to 10 atomic% or less
Came. For example, in US Pat. No. 4,836,868, B is
Disclosed is an example of 5 to 9.5 atomic%, and further, B is preferred.
4 atom% or more and less than 12 atom% as a preferable range, more preferable
The range of 4 atom% or more and 10 atom% or less
is doing.

On the other hand, in the sample to which Ti is added, as can be seen from FIG. 3, the maximum magnetic energy product (BH) _max is improved in a certain range where B exceeds 10 atomic%. This improvement is particularly remarkable when the Nd content is 8 to 10 atomic%.

As described above, according to the present invention, it is possible to obtain an effect by adding Ti, which is unexpected from the conventional technical common sense that the magnetic characteristics are deteriorated when B exceeds 10 atomic%.

Next, a method for producing a quenched alloy for Ti-containing nanocomposite magnetic powder will be described.

First, the molten metal of the alloy represented by the above composition formula is cooled in an inert atmosphere, whereby R ₂ Fe ₁₄
A quenched alloy containing, for example, 60% by volume or more of the B-type compound phase is prepared. The average crystal grain size of the R ₂ Fe ₁₄ B type compound phase in the quenched alloy can be, for example, 80 nm or less. If necessary, the quenched alloy is heat-treated to crystallize the amorphous material remaining in the quenched alloy.

The molten alloy is cooled in an atmosphere having a pressure of 1.3 kPa or more by using a quenching method using a cooling roll such as a melt spinning method and a strip casting method. As a result, not only is the molten alloy melt rapidly cooled by contact with the cooling roll, but also after being separated from the cooling roll, the molten alloy is appropriately cooled by the secondary cooling effect of the atmospheric gas.

According to the experiment conducted by the present inventor, the pressure of the atmospheric gas at the time of quenching is 1.3 kPa or more and the atmospheric pressure (10
1.3 kPa) or less, preferably 10 k
It is more preferable to set it in the range of Pa to 90 kPa. A more preferable range is 20 kPa or more and 60 kPa or less.

Under the above atmosphere gas pressure, the roll surface peripheral velocity is preferably in the range of 5 m / sec to 20 m / sec. When the roll surface peripheral velocity exceeds 20 m, the average thickness of the quenched alloy becomes less than 40 μm. as a result,
It becomes impossible to obtain a desired particle size distribution in the grinding process.
On the other hand, when the peripheral surface speed of the roll is lower than 5 m / sec, the average thickness of the quenched alloy exceeds 90 μm, and the desired particle size distribution cannot be obtained in the pulverizing step. Further, the crystal grains of the R ₂ Fe ₁₄ B type compound phase contained in the quenched alloy may become coarse. As a result, by heat treatment, R ₂ Fe ₁₄
The B-type compound phase becomes larger and the magnetic properties may deteriorate.

According to the experiment, the roll surface peripheral velocity is more preferably in the range of 5 m / sec to 20 m / sec, and still more preferably in the range of 7 m / sec to 18 m / sec. In particular, it is most preferable that the roll surface peripheral velocity is in the range of 8 m / sec or more and 16 m / sec or less.

In the present invention, coarse α is contained in the quenched alloy.
Hardly precipitating -fe, tissue having fine R ₂ Fe ₁₄ B compound phase, or tissue and an amorphous phase having fine R ₂ Fe ₁₄ B type compound phase are mixed tissue is produced. As a result, it is possible to obtain a high-performance nanocomposite permanent magnet in which a soft magnetic phase such as an iron-based boride phase is present in a finely dispersed state or a thinly spread state between the hard magnetic phases (grain boundaries) after heat treatment. it can. Note that the "amorphous phase" in the present specification is not limited to a phase constituted only by a portion in which the atomic arrangement is completely disordered, but also a crystallization precursor or microcrystal (size: several nm or less),
Alternatively, it also includes a phase partially containing an atomic cluster. Specifically, a phase whose crystal structure cannot be clearly identified by X-ray diffraction or transmission electron microscope observation is broadly referred to as an "amorphous phase".

Conventionally, a molten alloy having a composition similar to the composition of the present invention (but not containing Ti) is cooled and rapidly cooled to contain R ₂ Fe ₁₄ B type compound phase in an amount of 60% by volume or more. When an alloy is produced, an alloy structure in which a large amount of α-Fe is precipitated is obtained, so that there is a problem that α-Fe becomes coarse in the subsequent crystallization heat treatment.
When the soft magnetic phase such as α-Fe is coarsened, the magnetic properties are significantly deteriorated, and a bonded magnet that can withstand practical use cannot be obtained at all.

In particular, when the content of B is relatively large as in the raw material alloy composition used in the present invention, a crystal phase is generated even if the cooling rate of the molten alloy is slowed due to the high amorphous forming ability of B. It was difficult. Therefore, according to the prior art, the cooling rate of the molten alloy is sufficiently reduced to obtain R ₂ Fe ₁₄
If an attempt is made to produce a rapidly solidified alloy in which the volume ratio of the B-type compound phase exceeds 60%, in the prior art, R ₂ Fe ₁₄
In addition to the B-type compound phase, a large amount of α-Fe or its precursor is deposited, and the subsequent crystallization heat treatment causes α-Fe.
The coarsening of the phase progressed, and the magnetic characteristics deteriorated significantly.

From the above, conventionally, in order to increase the coercive force of the raw material alloy for the nanocomposite magnet magnetic powder, the cooling rate of the molten alloy is increased so that most of the rapidly solidified alloy is occupied by the amorphous phase. After that, it was common knowledge that it is preferable to form a uniformly refined structure from the amorphous phase by crystallization heat treatment. This is because in order to obtain a nanocomposite having an alloy structure in which fine crystal phases are dispersed, it was thought that crystallization should be performed from the amorphous phase in a heat treatment process that is easily controlled.

For this reason, L having an excellent amorphous forming ability
After a is added to the raw material alloy and the melt of the raw material alloy is rapidly cooled to produce a rapidly solidified alloy having an amorphous phase as a main phase, both the Nd ₂ Fe ₁₄ B phase and the α-Fe phase are subjected to crystallization heat treatment. It has been reported that the technique of precipitating and growing the slag and making each phase as fine as several tens of nm (W.
C. Chan, et.al. "THE EFFECTS OF REFRACTORY METALS O
N THE MAGNETIC PROPERTIES OF α-Fe / R ₂ Fe ₁₄ B-TYPE NA
NOCOMPOSITES ", IEEE, Trans. Magn. No. 5, INTERMAG.
99, Kyongiu, Korea pp.3265-3267, 1999). In addition, this paper shows that the addition of a trace amount of refractory metal elements such as Ti (2 atomic%) improves the magnetic properties, and that the composition ratio of rare earth element Nd is 11.0 atomic% rather than 9.5 atomic%. %
It has been taught that the increase in the Nd ₂ Fe ₁₄ B phase and the α-Fe phase is preferable for increasing the grain size.
The above refractory metal is added by adding boride (R ₂ Fe ₂₃ B ₃ or Fe
The production of ₃ B) inhibited, Nd ₂ Fe ₁₄ B phase and alpha-Fe
It is carried out in order to produce a raw material alloy for magnet powder consisting of only two phases.

On the other hand, in the present invention, the function of the added Ti suppresses the precipitation of the α-Fe phase in the rapid solidification step, and further, the iron-based boride and the soft magnetic phase are generated in the crystallization heat treatment step. By suppressing the coarsening, magnetic powder having excellent magnetic properties can be obtained. By utilizing such an effect of adding Ti, the average thickness is 40
Even if a relatively thick quenched alloy having a thickness of μm or more and 90 μm or less is produced, it becomes possible to exhibit excellent magnetic properties.

According to the present invention, the magnetization (residual magnetic flux density) and the coercive force are high and the squareness of the demagnetization curve is obtained while using a raw material alloy having a relatively small amount of rare earth element (for example, 9 atomic% or less). It is also possible to produce excellent magnet powder.

[0097] As described above, an increase in the coercivity of the Ti-containing nanocomposite magnet powder for raw material alloy according to the present invention, Nd ₂
This is achieved by preferentially precipitating and growing the Fe ₁₄ B phase in the cooling process, thereby increasing the volume ratio of the Nd ₂ Fe ₁₄ B phase and suppressing the coarsening of the soft magnetic phase. In addition, the increase in magnetization is caused by the action of Ti, which produces a boride phase such as a ferromagnetic iron-based boride from the B-rich non-magnetic amorphous phase existing in the rapidly solidified alloy, resulting in a strong strength after the crystallization heat treatment. It is considered that it was obtained because the volume ratio of the magnetic phase was increased.

The raw material alloy obtained as described above is subjected to crystallization heat treatment, if necessary, to obtain R ₂ Fe.
_{14 including} B-type compound phase, boride phase, and α-Fe phase 3
It is preferable to form a structure containing more than one kind of crystalline phase. In this structure, the average crystal grain size of the R ₂ Fe _{1 4} B type compound phase is 10 nm or more and 200 nm or less, the boride phase and α
The heat treatment temperature and time are adjusted so that the average crystal grain size of the —Fe phase is 1 nm or more and 100 nm or less. R ₂ Fe
The average crystal grain size of the ₁₄ B type compound phase is usually 30 nm or more, but it is 50 nm or more depending on the conditions. The average crystal grain size of a soft magnetic phase such as a boride phase or α-Fe phase is often 30 nm or less, and typically only a few nm.

The average grain size of the soft magnetic phase in the final raw material alloy for magnet powder is smaller than the average grain size of the R ₂ Fe ₁₄ B type compound phase (hard magnetic phase), and the R ₂ Fe ₁₄ B type compound It exists at the grain boundary of the phase. FIG. 4 schematically shows the metallographic structure of this raw material alloy. As you can see from Figure 4,
Fine soft magnetic phases are dispersed and exist between the relatively large R ₂ Fe ₁₄ B type compound phases. Thus R ₂ Fe ₁₄
Even if the average crystal grain size of the B-type compound phase becomes relatively large,
Since the crystal growth of the soft magnetic phase is suppressed and the average crystal grain size is sufficiently small, each constituent phase is magnetically coupled by the exchange interaction, and as a result, the magnetization direction of the soft magnetic phase is restricted by the hard magnetic phase. As a result, the alloy as a whole can exhibit excellent demagnetization curve squareness.

The reason why boride is likely to be produced in the above-mentioned production method is that when a solidified alloy in which the R ₂ Fe ₁₄ B type compound phase occupies the majority is produced, the amorphous phase present in the quenched alloy inevitably contains excessive B. It is considered that this is because this B is likely to combine with other elements in the crystallization heat treatment to precipitate and grow. However, if a compound with low magnetization is generated by the combination of B and other elements, the magnetization of the alloy as a whole will be reduced.

According to the experiments conducted by the present inventor, only when Ti is added, unlike the case where other kinds of metals such as V, Cr, Mn, Nb, and Mo are added, there is no decrease in magnetization.
Rather, it was found that the magnetization was improved. Further, when M (particularly Ti) was added, the squareness of the demagnetization curve became particularly good as compared with the other additive elements described above. From these facts, it is considered that Ti plays a particularly important role in suppressing the formation of boride having low magnetization. In particular,
In the composition range of the raw material alloy used in the present invention, B and T
When i is relatively small, an iron-based boride phase having ferromagnetism is likely to precipitate by heat treatment. In this case, B contained in the non-magnetic amorphous phase is taken into the iron-based boride, and as a result, the volume ratio of the non-magnetic amorphous phase remaining after the crystallization heat treatment decreases and the ferromagnetic crystal phase increases. It is considered that the residual magnetic flux density B _r is improved.

Hereinafter, this point will be described in more detail with reference to FIG.

FIG. 5 shows the case where Ti is added and T
It is a figure which shows typically the change of the microstructure in the crystallization process of the rapid solidification alloy when Nb etc. are added instead of i. When Ti is added, grain growth of each constituent phase is suppressed in a temperature range higher than the temperature at which α-Fe precipitates, and excellent hard magnetic properties are maintained. On the other hand, when a metal element such as Nb, V, or Cr is added, the grain growth of each constituent phase remarkably progresses in a relatively high temperature region where α-Fe precipitates, and it acts between each constituent phase. As a result of weakening the exchange interaction, the squareness of the demagnetization curve is greatly reduced.

First, the case where Nb, Mo and W are added will be described. In this case, if the heat treatment is performed in a relatively low temperature region where α-Fe does not precipitate, it is possible to obtain good hard magnetic characteristics with excellent squareness of the demagnetization curve. However, in the alloy heat-treated at such a temperature, R ₂ Fe ₁₄
It is presumed that the B-type fine crystal phase is dispersed and present in the non-magnetic amorphous phase, and since the nanocomposite structure is not formed, high magnetization cannot be expected. Also,
When the heat treatment is performed at a higher temperature, the α-Fe phase is precipitated out of the amorphous phase. Unlike the case where Ti is added, this α-Fe phase rapidly grows and coarsens after precipitation. For this reason, the exchange coupling between the constituent phases becomes weak, and the squareness of the demagnetization curve is greatly deteriorated.

On the other hand, when Ti is added, the R ₂ Fe ₁₄ B type crystal phase, the iron-based boride phase, and α-Fe are heat treated.
A nanocomposite structure containing a phase and an amorphous phase is obtained, and each constituent phase is uniformly miniaturized. Further, when Ti is added, the growth of the α-Fe phase is suppressed.

When V or Cr is added, these added metals form a solid solution with Fe and are antiferromagnetically coupled with Fe, resulting in a large decrease in magnetization. Further, when V or Cr is added, grain growth due to heat treatment is not sufficiently suppressed,
The squareness of the demagnetization curve deteriorates.

Only when Ti is added in this way, α-
It is possible to appropriately suppress the coarsening of the Fe phase and form a ferromagnetic iron-based boride. Further, Ti is an element that delays the precipitation of Fe primary crystals (γ-Fe that is transformed into α-Fe later) during liquid quenching and facilitates the formation of a supercooled liquid.
Since it plays an important role together with C and C, even if the cooling rate at the time of rapidly cooling the molten alloy is set to a relatively low value of about 10 ² ° C / sec to 10 ⁵ ° C / sec, α-Fe does not precipitate significantly. , R ₂ Fe ₁₄ B type crystal phase and an amorphous phase can be mixed to produce a quenched alloy. This is
Among various liquid quenching methods, the strip casting method, which is particularly suitable for mass production, can be adopted, which is extremely important for cost reduction.

As a method for rapidly cooling the molten alloy to obtain the raw material alloy, the strip casting method, in which the molten metal is poured directly from the tundish onto the cooling roll without controlling the flow rate of the molten metal with a nozzle or an orifice, has high productivity. It is a low cost method. In order to make the molten metal of the R—Fe—B rare earth alloy amorphous in the cooling rate range that can be achieved by the strip casting method, it is usually necessary to add 10 atomic% or more of B. When a large amount of B is added in the conventional technique, after the crystallization heat treatment is performed on the quenched alloy, in addition to the non-magnetic amorphous phase, coarse α-Fe and soft magnetic phase Nd ₂ Fe ₂₃ B _A homogeneous fine crystal structure cannot be obtained because _three phases are precipitated. As a result, the volume ratio of the ferromagnetic phase is reduced, and the coercive force is significantly reduced due to the reduction of the magnetization and the abundance ratio of the Nd ₂ Fe ₁₄ B phase. However, when Ti is added as in the present invention,
As described above, phenomena such as suppression of coarsening of the α-Fe phase occur, and the magnetization unexpectedly improves.

It should be noted that it is easier to obtain high final magnetic properties when the quenched alloy contains more Nd ₂ Fe ₁₄ B phase than when the quenched alloy contains much amorphous phase. The volume ratio of the Nd ₂ Fe ₁₄ B phase in the quenched alloy is preferably not less than half of the whole, specifically 60% by volume or more. The value of 60% by volume is measured by Moessbauer spectrum spectroscopy.

Next, the preferred embodiments of the present invention will be described more specifically.

[Cooling Device for Molten Alloy] In this embodiment,
For example, a raw material alloy is manufactured using the quenching apparatus shown in FIG. In order to prevent the oxidation of the raw material alloy containing the rare earth element R or Fe, which is easily oxidized, it is preferable to execute the alloy production process in an inert gas atmosphere. A rare gas such as helium or argon or nitrogen can be used as the inert gas. Since nitrogen is relatively easy to react with the rare earth element R, it is preferable to use a rare gas such as helium or argon.

The apparatus shown in FIG. 6 is provided with a melting chamber 1 and a quenching chamber 2 for the raw material alloy, which can maintain the vacuum or inert gas atmosphere and adjust the pressure thereof. FIG. 6A is an overall configuration diagram, and FIG. 6B is a partially enlarged view.

As shown in FIG. 6A, the melting chamber 1
Is a raw material 2 formulated to have a desired magnet alloy composition.
Melting furnace 3 for melting 0 at high temperature, and tapping nozzle 5 at the bottom
A hot water storage container 4 having the above and a blended raw material supply device 8 for feeding the blended raw material into the melting furnace 3 while suppressing the entry of the atmosphere. The hot water storage container 4 has a heating device (not shown) capable of storing the molten metal 21 of the raw material alloy and maintaining the temperature of the molten metal at a predetermined level.

The quenching chamber 2 has the molten metal 2 discharged from the molten metal discharge nozzle 5.
A rotary cooling roll 7 for rapidly solidifying 1 is provided.

In this apparatus, the atmosphere and its pressure in the melting chamber 1 and the quenching chamber 2 are controlled within a predetermined range. Therefore, the atmospheric gas supply ports 1b, 2b, and 8b and the gas exhaust ports 1a, 2a, and 8a are provided at appropriate places of the apparatus. In particular, the gas exhaust port 2a is connected to a pump in order to control the absolute pressure in the quenching chamber 2 within the range of 30 kPa to normal pressure (atmospheric pressure) (preferably 100 kPa or less). By changing the pressure of the melting chamber 1, the injection pressure of the molten metal discharged from the nozzle 5 can be adjusted.

The melting furnace 3 is tiltable, and the molten metal 21 is appropriately poured into the hot water storage container 4 via the funnel 6. Molten metal 21
Is heated in the hot water storage container 4 by a heating device (not shown).

The hot water discharge nozzle 5 of the hot water storage container 4 is disposed on the partition wall between the melting chamber 1 and the quenching chamber 2, and the molten metal 21 in the hot water storage container 4 is
To the surface of the cooling roll 7 located below. The orifice diameter of the tapping nozzle 5 is 2.0 mm or more and 4.0 m
It is set within a range of m or less (for example, 2.8 mm). When the viscosity of the molten metal 21 is high, the molten metal 21 is less likely to flow in the hot water discharge nozzle 5 and is likely to cause variations in the thickness of the quenched alloy. However, in the present embodiment, the orifice diameter is increased as compared with the conventional case, and the quenching chamber 2 Is maintained at a pressure sufficiently lower than that of the melting chamber 1, a large pressure difference (differential pressure exceeding 10 kPa) is formed between the melting chamber 1 and the quenching chamber 2, and the molten metal 21 is smoothly discharged. To be executed. According to the apparatus used in this embodiment, the supply rate of the molten alloy is 1.
It can be set to 5 to 10 kg / min. If the supply rate exceeds 10 kg / min, the molten metal quench rate will slow down,
The disadvantage that coarse α-Fe precipitates occurs. A more preferable supply rate of the molten alloy is 3 to 7 kg / min. In this case, it is possible to obtain a quenched alloy of 40 μm or more and 90 μm or less at an appropriate roll peripheral speed.

The cooling roll 7 is made of Cu, Fe, or Cu.
It is preferably formed from an alloy containing Fe or Fe. If the cooling roll is made of a material other than Cu or Fe, the exfoliation property of the quenched alloy from the cooling roll deteriorates, and therefore the quenched alloy may be wound around the roll, which is not preferable. The inner diameter of the cooling roll 7 is, for example, 300 to 500 mm. The water cooling capacity of the water cooling device provided in the cooling roll 7 is calculated and adjusted according to the solidification latent heat and the amount of tapping water per unit time.

[Quenching Method] First, the melt 21 of the raw material alloy represented by the above-mentioned composition formula is prepared and stored in the storage container 4 of the melting chamber 1 in FIG. Next, the molten metal 21 is tapped from the tapping nozzle 5 onto the water-cooled roll 7 in the reduced pressure Ar atmosphere, and is rapidly cooled by contact with the cooling roll 7 and solidified. Cooling rate of the molten alloy is preferably adjusted to 1 × 10 ² ~10 ⁸ ℃ / sec, it is preferable to ^{1 × 10 2 ~1 × 10 6} ℃ / sec.

The time during which the molten metal 21 of the alloy is cooled by the cooling roll 7 corresponds to the time from the time when the alloy comes into contact with the outer peripheral surface of the rotating cooling roll 7 until the time when the alloy separates from the outer circumferential surface of the rotating cooling roll 7, and the temperature of the alloy decreases during that time. , Solidify.

In this embodiment, the roll surface speed is 5 m /
It is adjusted within the range of not less than 2 seconds and not more than 15 m / second, and the atmosphere gas pressure is set to 13 kPa or more in order to enhance the secondary cooling effect by the atmosphere gas.

The method for quenching the molten alloy used in the present invention is not limited to the above-mentioned one-roll method, and a strip casting method which is a quenching method in which the flow rate is not controlled by the nozzle orifice may be used. In the case of the strip casting method, since the nozzle orifice is not used, there is an advantage that the molten metal supply rate can be increased and can be easily stabilized. However, the atmospheric gas is likely to be caught between the cooling roll and the molten metal, and the cooling rate on the quenching surface side may be uneven. In order to solve such a problem, it is necessary to reduce the atmospheric pressure of the space in which the cooling roll is placed to the above-mentioned range to suppress the entrainment of the atmospheric gas.

(Embodiment 2) Next, a second embodiment using the strip casting method will be described.

In this embodiment, the peripheral speed is 5 m / sec or more 20
A supply rate per unit contact width of 1.2 kg / min / cm or more and 3.0 kg on a cooling roll that rotates at less than m / sec.
/ Min / cm or less to continuously supply the molten metal. By setting in this way, a raw material alloy for permanent magnet powder in which the amorphous structure occupies 60% by volume or more can be produced.

In this embodiment, the range of the appropriate molten metal supply rate is defined by the supply rate per unit contact width as described above. In the case of the strip casting method, the molten metal comes into contact with the cooling roll so as to have a predetermined contact width along the axial direction of the cooling roll, but the cooling condition of the molten metal largely depends on the molten metal supply rate per unit contact width. Is. The supply rate per unit contact width is typically the supply rate (unit: kg / min) of the molten metal supplied onto the chute for guiding the molten metal, , Contact width of molten metal) (unit: cm). When there are a plurality of discharge parts of the chute, the supply rate of the molten metal supplied to the chute is divided by the total width of the discharge parts.

If the molten metal supply rate per unit contact width is too large, the cooling rate of the molten metal by the chill roll decreases,
As a result, a quenched alloy containing a large amount of crystallized structure is produced without promoting amorphization, and a raw material alloy suitable for a nanocomposite magnet cannot be obtained. Further, if the molten metal supply rate is too small, it becomes difficult for the strip casting method to bring the molten metal into contact with the cooling roll in an appropriate state. Therefore, in the present invention, the supply rate per unit contact width is set to 0.3 kg / min / cm or more and 5.2 kg / min / cm or less.

Further, as will be described later, for example, when the molten metal is brought into contact with the cooling roll in a contact form in which three contact portions each having a contact width of about 2 cm are provided, the supply rate is set to about 0.5 kg / min / cm or more. As a result, a throughput of about 3 kg / min or more can be realized.

As described above, by supplying the molten metal to the cooling rolls rotating at the peripheral speed in the specific range at the supply rate in the specific range, even when the strip casting method is used, the thickness variation is small. A quenched alloy can be produced with high productivity. Unlike the melt spinning method, the strip casting method does not use a nozzle that significantly increases the manufacturing cost. Therefore, the cost for the nozzle is unnecessary, and the production is not stopped due to a nozzle clogging accident.

Thereafter, about 5% was added to the obtained quenched alloy.
One of the α-Fe phase or the Fe ₃ B type compound by performing a heat treatment for crystallization (hereinafter also referred to as “crystallization heat treatment”) in a temperature range of 00 ° C. to about 900 ° C. Or 90% of the crystal structure in which the soft magnetic phase consisting of two kinds and the compound having the R ₂ Fe ₁₄ B type crystal structure coexist
It is possible to obtain the nanocomposite permanent magnet having good magnetic characteristics and having the average crystal grain size of 10 nm to 50 nm.

This embodiment will be described below with reference to the drawings.

FIG. 7 shows a quenching apparatus for producing a quenched alloy by the strip casting method according to this embodiment. The quenching device is provided with a main chamber 30 whose inside can be brought into a vacuum state or a reduced pressure state in an inert gas atmosphere, and a sub-chamber 50 connected to the main chamber 30 via an openable / closable shutter 48. .

Inside the main chamber 30, a melting furnace 32 for melting the alloy raw material, a cooling roll 34 for rapidly cooling and solidifying the molten alloy 23 supplied from the melting furnace 32, and a cooling from the melting furnace 32. A chute (tundish) 3 as a molten metal guiding means for guiding the molten metal 23 to the roll 34
6 and a recovery means 40 for recovering the ribbon-shaped alloy solidified and separated from the cooling roll 34.

The melting furnace 32 can supply the melt 23 produced by melting the alloy raw material to the chute 36 at a substantially constant supply amount. This supply amount can be arbitrarily adjusted by controlling the operation of tilting the melting furnace 32.

The outer peripheral surface of the cooling roll 34 is made of a material having good thermal conductivity such as copper, and has an inner diameter of 30 c.
It has a dimension of m to 100 cm and a width of 15 to 100 cm. The cooling roll 34 can be rotated at a predetermined rotation speed by a driving device (not shown). By controlling this rotation speed, the peripheral speed of the cooling roll 34 can be arbitrarily adjusted. The cooling rate by the quencher is
By selecting the rotation speed of the cooling roll 34,
It can be controlled in the range of about 10 ² ° C / sec to about 2 x 10 ⁴ ° C / sec.

The end 36a of the chute 36 is arranged at a position having an angle θ with respect to a line connecting the top of the cooling roll 34 and the center of the roll (0 ° <θ <18.
0 °, preferably 0 ° ≦ θ ≦ 90 °). The molten metal 23 supplied onto the chute 36 is cooled by the cooling roll 3 from the end 36a.
4 is supplied by its own weight. The angle (tilt angle) formed by the molten metal guide surface of the chute 36 with respect to the horizontal direction
Is preferably set within the range of 1 to 80 °. In the present embodiment, the angle θ is set to 40 ° and the tilt angle of the molten metal guide surface with respect to the horizontal direction of the chute 36 is set to 20 °.

The chute 36 is made of ceramics or the like and temporarily stores the molten metal 23 continuously supplied from the melting furnace 32 at a predetermined flow rate to delay the flow velocity and rectify the flow of the molten metal 23. be able to. The rectification effect can be further improved by providing a damming plate that can selectively dam the flow of the molten metal surface portion in the molten metal 23 supplied to the chute 36.

By using the chute 36, the molten metal 23 can be supplied in a state where the cooling roll 34 is spread over a certain width to a substantially uniform thickness in the cylinder length direction (axial direction). In addition to the above functions, the chute 36 also has a function of adjusting the temperature of the molten metal 23 immediately before reaching the cooling roll 34. The temperature of the molten metal 23 on the chute 36 is preferably 100 ° C. or more higher than the liquidus temperature. This is because if the temperature of the molten metal 23 is too low, primary crystals that adversely affect the alloy properties after quenching may locally nucleate and remain after solidification. The molten metal retention temperature on the chute 36 can be controlled by adjusting the molten metal temperature at the time of pouring from the melting furnace 32 into the chute 36, the heat capacity of the chute 36 itself, and the like, if necessary, a chute heating facility (not shown). ) May be provided.

FIG. 8 shows a chute 36 used in this embodiment.
Indicates. The chute 36 has a plurality of discharge portions 36b provided at an end portion 36a arranged so as to face the outer peripheral surface of the cooling roll 34 and separated by a predetermined distance W2. The width (outflow width) W1 of this discharge part 36b is
It is preferably set to 0.5 mm to 30 mm, and more preferably set to 0.7 mm to 20 mm. In this embodiment, the tapping width W1 is set to 10 mm.

The molten metal 23 supplied onto the chute 36 is
Along the axial direction A of the cooling roll 34, the cooling roll 34 comes into contact with the cooling roll 34 while having a width substantially the same as the width W1. afterwards,
The molten metal 23 that comes into contact with the cooling roll 34 with the tapping width W1 moves along the rotation of the cooling roll 34 (so as to be pulled up by the cooling roll 34) and is cooled in this moving process. The distance between the end 36a of the chute 36 and the cooling roll 34 is preferably set to 3 mm or less in order to prevent the molten metal from leaking.
The gap W2 between the adjacent discharge portions is preferably 0.1 mm.
It is set to ˜2 mm.

By thus separating the molten metal contact portion (molten metal cooling portion) on the outer peripheral surface of the cooling roll 34 into a plurality of locations, each molten metal can be supplied while increasing the amount of molten metal supplied to the cooling roll 34 per unit time. Cooling becomes possible under substantially uniform conditions for each flow. As a result, even if a quenched alloy having a thickness of more than 40 μm is produced, it is possible to stably produce a quenched alloy with reduced thickness variation.

Referring again to FIG. The molten alloy 23 solidified on the outer peripheral surface of the cooling roll 34 becomes a strip-shaped solidified alloy 23 a and is separated from the cooling roll 34. The separated solidified alloy 23a is crushed and collected in the collecting device 40.

The recovery device 40 is composed of a ribbon-shaped solidified alloy 23a.
It is equipped with a rotating blade 42 for crushing. The rotary blade has a plurality of blades formed of, for example, stainless steel, and is driven by a drive device (not shown) to
It can be rotated at a speed of about 1000 rpm. The strip-shaped solidified alloy 23 a from which the cooling roll 34 has been peeled off is guided to the rotary blade 42 by the guide member 44. Since the solidified alloy 23a produced in this embodiment using the strip casting method is relatively thick (40 μm to 90 μm),
Crushing by the rotating blade 42 is easier than the relatively thin solidified alloy obtained by the conventional melt spinning method.

Since the band-shaped solidified alloy 23a is relatively thick as described above, the shape of the solidified alloy 25 crushed by the rotary blade 42 has an aspect ratio closer to 1. Therefore, the solidified alloy 25 after crushing can be stored in the recovery container 46 in a state where the bulk density is high.
Solidified alloy 25 is preferably recovered at a bulk density of at least 1 g / cm ³ . As a result, the efficiency of the recovery work can be improved.

The recovery container 46 in which a predetermined amount of the crushed solidified alloy 25 is stored is sent to the sub-chamber 50 by moving means (not shown) such as a belt conveyor. At this time, before the shutter 48 is opened, it is desirable that the inside of the sub-chamber 50 is under the same vacuum as the main chamber 30 or under a reduced pressure using an inert gas. Thereby, the vacuum state or the reduced pressure state in the main chamber 30 can be maintained. After the recovery container 46 is carried out from the main chamber 30, the shutter 48 is closed and the airtightness of the main chamber 30 is maintained.

Then, in the sub-chamber 50, the recovery container 46 is covered with a lid 52 by an apparatus (not shown). In this way, the crushed alloy 25 sealed in the recovery container 46 is carried out to the outside by opening the shutter 54 that can be opened and closed.

As described above, in the present embodiment, the molten alloy having the specific composition is rapidly cooled and solidified by the strip casting method using the quenching device shown in FIG.
A ribbon-shaped alloy is prepared. The molten alloy has a supply rate per unit contact width of 0.3 kg / min / cm with respect to a cooling roll that rotates at a peripheral speed of 5 m / sec or more and less than 20 m / sec under vacuum or reduced pressure in an inert gas atmosphere. The above is supplied at 5.2 kg / min / cm or less. In this way, it is possible to produce a quenched alloy having an amorphous structure of 60% by volume or more. By performing the crystallization heat treatment on the raw material alloy having the amorphous structure at such a high ratio, a nanocomposite type magnet having good magnetic properties can be manufactured.

As described above, the peripheral speed of the cooling roll is 5 m.
/ Sec or more and less than 20 m / sec is set because when the roll peripheral speed is less than 5 m / sec, the thickness of the quenched alloy is 90 μm.
On the other hand, when the peripheral speed of the cooling roll is 20 m / sec or more, the thickness of the quenched alloy is less than 40 μm.

As described above, the reason why the supply rate per unit contact width in this embodiment is 5.2 kg / min / cm or less is that when the supply rate exceeds 5.2 kg / min / cm, the quenched alloy is used. Is too thick, exceeding 90 μm, and a predetermined cooling rate cannot be obtained.
An appropriate range of the supply rate per unit contact width may differ depending on the roll peripheral speed, roll structure, etc., but is 4.0
It is preferably not more than kg / min / cm, and 3.0 kg
More preferably, it is not more than / minute / cm.

When the roll peripheral velocity is 5 m / sec or more, the supply rate per unit contact width is 0.3 kg / min / min.
If it is smaller than cm, the average thickness is 40μ, which has a uniform thickness.
It is not possible to obtain a quenched alloy of m or more.

By appropriately selecting the shape of the chute (tundish), the width and number of the molten metal discharge part, the molten metal supply rate, etc., the thickness and width of the obtained ribbon-shaped quenched alloy can be controlled within the proper range. It is also important to ensure that In order to obtain a uniform structure, it is also necessary to make the cooling rate uniform in the width direction. For that purpose, it is preferable to set the width of the ribbon-shaped quenched alloy within the range of 5 mm to 40 mm.

When the inside of the chamber is depressurized by using an inert gas, if the inert gas atmosphere pressure during casting is too high, the inert gas around the roll may be generated when the cooling roll is rotating at a high speed. Entrainment occurs and a stable cooling state cannot be obtained. On the other hand, if the atmospheric pressure is too low, the ribbon-shaped alloy separated from the roll is not rapidly cooled by the inert gas, so that crystallization progresses and an alloy containing a large amount of amorphous cannot be produced. In this case, the magnetic properties of the alloy obtained after the crystallization heat treatment deteriorate. From these, the inert gas pressure is 0.13 kPa to 100 kP.
It is preferable to adjust to a.

As described above, in the melt spinning method and the strip casting method, the average thickness of the quenched alloy can be controlled by adjusting the molten metal supply rate and the roll surface peripheral speed. As described above, in order to obtain an ideal particle size distribution, the average thickness of the quenched alloy is 40 μm or more and 9 μm or more.
It is necessary to set it in the range of 0 μm or less.

When the peripheral velocity of the roll surface is increased to make the average thickness of the alloy thinner than 40 μm, the metallographic structure of the alloy tends to be aligned in the direction perpendicular to the roll contact surface as in the case of conventional quenching magnets. . Therefore, it is easy to break along that direction, the powder particles obtained by pulverization are likely to have a shape that extends flat along the direction parallel to the surface of the alloy, and powder particles with an aspect ratio of less than 0.3 are generated. Easy to be affected. As a result, only a tap density of 3.0 g / cm ³ can be obtained, and a molding density of 6.0 g / cm ³ or more cannot be finally achieved. Further, if the average thickness exceeds 90 μm, there arises a problem that a desired particle size distribution cannot be obtained.

FIG. 9A schematically shows the alloy 10 before the crushing step and the powder particles 11 after the crushing step in the magnet powder manufacturing method according to the present embodiment. On the other hand, FIG.
(B) schematically shows the alloy ribbon 12 before the pulverizing step and the powder particles 13 after the pulverizing step in the conventional method for producing a quenched magnet powder.

As shown in FIG. 9A, in the case of this embodiment, since the alloy 10 before crushing is composed of equiaxed crystals having a small crystal grain size, fracture occurs along random orientations. It is easy to produce equiaxed powder particles 11. On the other hand, in the case of the conventional quenched alloy, as shown in FIG.
As shown in (3), since the alloy ribbon 12 easily breaks in a direction substantially perpendicular to the surface thereof, the particle 13 has a flat shape.

As described above, since the Ti-containing nanocomposite quenched alloy is likely to fracture along random orientations,
By controlling the peripheral velocity of the roll surface and adjusting the thickness of the alloy ribbon, it is possible to easily obtain a powder having an aspect ratio of 0.3 or more, preferably 0.4 or more and 1.0 or less.

[Heat Treatment] In this embodiment, the heat treatment is performed.
Perform in a gon atmosphere. Preferably, the heating rate is set to 0.
08 ° C / sec to 20 ° C / sec, 500 ° C or higher and 900 ° C
After holding at the following temperature for 30 seconds or more and 20 minutes or less,
Cool to room temperature. Amorphous by this heat treatment
Fine crystals of metastable phase precipitate and grow in the phase,
A jitt structure is formed. According to this embodiment, heat
Already fine Nd at the start of processing ₂Fe₁₄B type crystal phase
Since 60% by volume or more of the whole is present, the α-Fe phase and
Coarsening of other crystal phases is suppressed, and Nd₂Fe₁₄B-type crystal
Each constituent phase (soft magnetic phase) other than the phases is uniformly miniaturized.

If the heat treatment temperature is lower than 500 ° C.,
A large amount of amorphous phase remains after the heat treatment, and the coercive force may not reach a sufficient level depending on the rapid cooling conditions.
Further, when the heat treatment temperature exceeds 900 ° C., grain growth of each constituent phase is remarkable, the residual magnetic flux density B _r decreases, and the squareness of the demagnetization curve deteriorates. Therefore, the heat treatment temperature is preferably 500 ° C. or higher and 900 ° C. or lower, but a more preferable heat treatment temperature range is 550 ° C. or higher and 850 ° C. or lower.

In this embodiment, a sufficient amount of Nd ₂ Fe ₁₄ B is contained in the quenched alloy due to the secondary cooling effect of the atmospheric gas.
The type compound phase is uniformly and finely precipitated. For this reason,
Even if the quenched alloy is not intentionally subjected to crystallization heat treatment, the rapidly solidified alloy itself can exhibit sufficient magnetic properties. Therefore, crystallization heat treatment is not an essential step,
It is preferable to do this to improve the magnetic properties.
The magnetic properties can be sufficiently improved even by heat treatment at a lower temperature than in the conventional case.

The heat treatment atmosphere is preferably an inert gas atmosphere in order to prevent oxidation of the alloy. The heat treatment may be performed in a vacuum of 0.1 kPa or less.

In the quenched alloy before heat treatment, R ₂ Fe ₁₄ B
Type compound phase and amorphous phase, Fe ₃ B phase,
A metastable phase such as Fe ₂₃ B ₆ and R ₂ Fe ₂₃ B ₃ phase may be contained. In that case, by the effect of Ti addition in the present invention, in the heat treatment, R ₂ Fe ₂₃ B ₃ phase disappears, R ₂
An iron-based boride (for example, Fe ₂₃ B ₆ ) or α-which exhibits a saturation magnetization equal to or higher than that of the Fe ₁₄ B phase.
Fe can be crystal-grown.

In the case of the present invention, even if a soft magnetic phase such as α-Fe is finally present, grain growth is suppressed by the effect of Ti and the structure is made fine. As a result, the soft magnetic phase and the hard magnetic phase are magnetically coupled by the exchange interaction, so that excellent magnetic characteristics are exhibited.

The average crystal grain size of the R ₂ Fe ₁₄ B type compound phase after the heat treatment needs to be 300 nm or less, which is a single domain crystal grain size, and 10 nm or more and 200 nm or less, and further 20 nm or more and 150 nm or less. Is preferable, and more preferably 20 nm or more and 100 nm or less. On the other hand, when the average crystal grain size of the boride phase or the α-Fe phase exceeds 100 nm, the exchange interaction acting between the constituent phases is weakened and the squareness of the demagnetization curve is deteriorated.
H) _max decreases. The average grain size of these is 1
If it is less than nm, a high coercive force cannot be obtained. From the above, the average crystal grain size of the soft magnetic phase such as boride phase or α-Fe phase is 1 nm or more and 100 nm or less, preferably 50 nm or less.
The thickness is preferably nm or less, and more preferably 30 nm or less.

The thin ribbon of the quenched alloy may be roughly cut or crushed before the heat treatment. After the heat treatment, the obtained alloy coarse powder (or thin strip) is pulverized to produce magnetic powder, whereby magnetic powder for a bonded magnet can be manufactured.

[Description of Grinding Process] As the Ti-containing nanocomposite magnetic powder for bonded magnets, those having a maximum particle size of 300 μm or less are used. In particular, in order to suppress shedding and the like in small magnets, the maximum particle size of the Ti-containing nanocomposite magnetic powder is preferably 250 μm or less, and 215 μm
It is more preferably m or less. When used for compression molding, the average particle size is preferably in the range of 50 μm to 200 μm, more preferably in the range of more than 53 μm and 125 μm or less.

As described above, at least the particle size of the Ti-containing nanocomposite magnetic powder of the present invention is 106 μm.
The aspect ratio of the particles exceeding m is 0.3 or more and 1.0 or less, and preferably 0.4 or more.

As described above, according to the production method of the present invention, the aspect ratio and the average particle size of the Ti-containing nanocomposite magnetic powder can be kept within the desired ranges described above, and the particle size of 2 peaks can be obtained in the pulverizing step. A magnet powder having a distribution can be produced.

[Reasons for limiting composition] The total amount of Q is B
(Boron) or a combination of B and C (carbon). C for the total amount of Q
Is preferably 0.25 or less.

When the composition ratio x of Q is 10 atomic% or less, when the cooling rate during quenching is relatively low at about 10 ² ° C / sec to 10 ⁴ ° C / sec, the R ₂ Fe ₁₄ B type crystal phase and the amorphous phase are It becomes difficult to produce a quenched alloy in which phases are mixed, and even if a heat treatment is applied thereafter, H of less than 400 kA / m
_{Only cJ} can be obtained. Further, the strip casting method, which has a relatively low process cost, cannot be adopted among the liquid quenching methods, and the price of the permanent magnet increases. On the other hand, when the composition ratio x of Q exceeds 17 atomic%, the precipitation of the iron-based boride starts at the same time as the precipitation of the R ₂ Fe ₁₄ B phase, so that the iron-based boride becomes coarse. As a result, it is not possible to obtain a nanocomposite structure in which the iron-based boride phase is uniformly dispersed or spread in a film shape at the R ₂ Fe ₁₄ B grain boundaries or subgrain boundaries, and the magnetic properties are deteriorated.

From the above, it is preferable to set the composition ratio x of Q to be more than 10 atom% and not more than 17 atom%. The more preferable upper limit of the composition ratio x is 16 atom%, and the still more preferable upper limit of the composition ratio x is 15 atom%.

The ratio p of C to the whole Q is preferably in the range of 0 or more and 0.25 or less in terms of atomic ratio. In order to obtain the effects of C addition such as the inhibition of TiB ₂ phase precipitation and the refinement of the metal structure, the C ratio p is preferably 0.01 or more. If p is less than 0.01, the effect of adding C is hardly obtained. On the other hand, if p is too large than 0.25, the amount of α-Fe phase produced increases, and the magnetic properties deteriorate. The lower limit of the ratio p is preferably 0.02,
The upper limit of p is preferably 0.20 or less. Ratio p
Is more preferably 0.08 or more and 0.15 or less.

R is a rare earth element (including yttrium)
Is one or more elements selected from the group When La or Ce are present, the R ₂ Fe ₁₄ B phase R (typically N
Since d) is replaced with La or Ce and coercive force and squareness are deteriorated, it is preferable that La and Ce are not substantially contained. However, when a small amount of La or Ce (0.5 atom% or less) is present as an impurity that is inevitably mixed, it can be said that there is no problem in terms of magnetic properties and substantially no inclusion. More specifically, R preferably contains Pr or Nd as an essential element, and a part of the essential element is Dy and / or
Alternatively, it may be replaced with Tb. When the composition ratio y of R is less than 6 atom% of the whole, R ₂ Fe necessary for developing coercive force is obtained.
₁₄ A compound phase having a B-type crystal structure was not sufficiently precipitated.
The coercive force H _cJ of 0 kA / m or more cannot be obtained. When the composition ratio y of R is 10 atomic% or more,
The abundance of iron-based borides and α-Fe having ferromagnetism decreases, and the abundance of B-rich non-magnetic phase increases instead, so that the nanocomposite structure is not formed and the magnetization decreases. Therefore, the composition ratio y of the rare earth element R is 6 atomic% or more 1
It is preferable to adjust to a range of less than 0 atomic%, for example, 7 atomic% or more and 9.5 atomic% or less. The more preferable upper limit of the R range is 9.3 atom%, and the further preferable upper limit of the R range is 9.0 atom%. The lower limit of the preferable range of R is 7.
It is 5 atom%, and the lower limit of the more preferable range of R is 8.
It is 0 atomic%. In the present invention, although the R concentration is low in this way, the R ₂ Fe ₁₄ B phase precipitates and grows preferentially over the other phases due to the action of Ti, so that R in the molten alloy is R ₂
It is effectively used for the formation of the Fe ₁₄ B phase, and the concentration of R is reduced in the grain boundary portion. As a result, the R concentration in the grain boundary phase becomes 0.5 atomic% or less, which is significantly lower than the R concentration in the hard magnetic phase (about 11 atomic%). Since R is used to form the effective hard magnetic phase in this manner (R ₂ Fe ₁₄ B phase) in the present invention, the composition ratio of R is less than 10 atomic%, the hard magnetic phase (R ₂ Fe ₁₄ Despite the volume ratio of (B phase) being 65 atomic% or more and 85 atomic% or less, excellent hard magnetic characteristics are exhibited by exchange coupling with the soft magnetic phase existing at the grain boundaries. In addition, R in the present specification
The volume ratio of constituent phases such as ₂ Fe ₁₄ B phase is a value measured by Moessbauer spectrum spectroscopy.

Ti is an essential element for obtaining the above-mentioned effect, contributes to the improvement of the coercive force H _cJ and the residual magnetic flux density B _r , and the squareness of the demagnetization curve, and the maximum energy product (BH ) Increase _max .

If the composition ratio z of Ti is less than 0.5 atom% of the whole, the effect of Ti addition is not sufficiently exhibited. On the other hand, when the composition ratio z of Ti exceeds 6 atomic% of the whole, the volume ratio of the nonmagnetic phase remaining after the crystallization heat treatment increases, so that the residual magnetic flux density B _r tends to decrease. From the above, the composition ratio z of Ti is 0.5 atom% or more and 6 atom% or more.
The following range is preferable. The more preferable lower limit of the range of z is 1.0 atom%, and the more preferable upper limit of the range of z is 5 atom%. A more preferable upper limit of the range of z is 4 atom%.

Further, as the composition ratio x of Q is higher, an amorphous phase containing excessive Q (for example, boron) is more likely to be formed. Therefore, it is preferable to increase the composition ratio z of Ti.
Ti has a strong affinity for B and is concentrated in a film form at the grain boundaries of the hard magnetic phase. If the ratio of Ti to B is too high, a large amount of non-magnetic TiB ₂ precipitates, and the volume ratio of the iron-based boride decreases, which may lower the magnetization. Further, if the ratio of Ti to B is too low, a large amount of magnetized B-rich amorphous phase is generated. According to the experiment, 0.05 ≦ z / x ≦ 0.
It is preferable to adjust the composition ratio so as to satisfy 4, and it is more preferable to satisfy 0.1 ≦ z / x ≦ 0.35. More preferably, 0.13 ≦ z / x ≦ 0.3.

Fe occupies the remaining content of the above elements, but desired hard magnetic characteristics can be obtained even if a part of Fe is replaced with one or two transition metal elements (T) of Co and Ni. it can. If the substitution amount of T with respect to Fe exceeds 50%, a high residual magnetic flux density B _{r of} 0.7 T or more cannot be obtained. Therefore, the substitution amount is preferably limited to the range of 0% to 50%. By substituting a part of Fe with Co, the squareness of the demagnetization curve is improved and the Curie temperature of the R ₂ Fe ₁₄ B phase is increased, so that the heat resistance is improved. The preferable range of the Fe substitution amount by Co is 0.5% or more and 40% or less.

In order to obtain various effects, the metal element M may be added within the range of 0 to 10 atomic%. M is Al, S
i, V, Cr, Mn, Cu, Zn, Ga, Zr, Nb,
It is at least one element selected from the group consisting of Mo, Hf, Ta, W, Pt, Pb, Au and Ag.

[Explanation of Compound and Magnet Manufacturing Method] The Ti-containing nanocomposite magnetic powder obtained as described above is mixed with a binder such as a resin to manufacture a bonded magnet compound.

The compound for compression molding is produced, for example, by mixing a thermosetting resin diluted with a solvent with magnetic powder and removing the solvent. The obtained mixture of magnetic powder and resin is crushed to have a predetermined particle size, if necessary. Granules may be obtained by adjusting the crushing conditions and the like. Moreover, you may granulate the powder material obtained by pulverization.

In order to improve the corrosion resistance of the Ti-containing nanocomposite magnetic powder, the surface of the magnetic powder may be subjected to a known surface treatment such as chemical conversion treatment in advance. Furthermore, in order to further improve the corrosion resistance of magnetic powder, the wettability with resin, and the moldability of compounds, various coupling agents such as silane-based, titanate-based, aluminate-based, and zirconate-based, ultrafine ceramic particles such as colloidal silica, and stearin Lubricants such as zincate and calcium stearate may be used, and heat stabilizers, flame retardants, plasticizers and the like may be used.

In the magnet compound, the type of resin and the compounding ratio of magnetic powder are appropriately determined according to the application. Examples of the resin include thermosetting resins such as epoxy resin, phenol resin and melamine resin, and polyamide (nylon 6
6, nylon 6, nylon 12 etc.), polyethylene,
Thermoplastic resins such as polypropylene, polyvinyl chloride, polyester, and polyphenylene sulfide, rubbers and elastomers, and modified products, copolymers, and mixtures thereof can be used.

By using the Ti-containing nanocomposite magnetic powder according to the present invention, it is possible to realize a higher magnetic powder filling rate (for example, more than 80%) than ever before, and to fill up to about 90% at maximum. However, if the filling rate is raised too much, the resin for sufficiently binding the magnetic particles to each other will be insufficient, and the mechanical strength of the bonded magnet will be reduced, and the magnetic particles may fall off during use. ,
It is preferably 85% or less. Further, by using the Ti-containing nanocomposite magnetic powder according to the present invention in compression molding, it is possible to reduce the amount of voids (voids) formed on the surface of the molded body and suppress adverse effects on the resin coating formed on the surface. Benefits are obtained. These molding methods include
A thermosetting resin, a thermoplastic resin, rubber or the like is appropriately used.

[Surface Treatment of Bond Magnet] By subjecting the bond magnet just after molding to the surface treatment, the corrosion resistance and heat resistance of the bond magnet can be improved. Since the compound according to the present invention is superior in moldability to the conventional compound, it is possible to obtain a bond magnet having a low porosity (void ratio) while ensuring a filling rate equal to or higher than that of the conventional compound. Therefore, it is possible to suppress / prevent the occurrence of the problem of corrosion that accompanies the surface treatment of the as-molded bonded magnet having many voids. Moreover, since the bonded magnet has high corrosion resistance, the cost can be reduced by simplifying the surface treatment.

Further, even when the bond magnet after molding has sufficient corrosion resistance, mechanical damage to the bond magnet during the assembly process, such as a compression-molded ring magnet used for a motor or the like, is avoided. To prevent
In some cases, it is necessary to prevent the adverse effect on the operation of the motor due to the scattering of the magnetic powder that has fallen off the surface of the bonded magnet. In such a case, it is preferable to perform various surface treatments in order to improve the mechanical strength of the bonded magnet and prevent the magnetic powder from falling off.

Even in such a case, since the protective film can be made thin, the dimensional accuracy of the entire bonded magnet including the protective film can be improved, and the effective volume of the magnet can be increased to downsize the component. There is also an advantage. Further, when incorporated in a motor, the magnetic characteristics between the rotor and the stator can be reduced, so that the motor characteristics can be improved.

As the surface treatment method, known methods can be widely used. The protective film formed by surface treatment is an inorganic material (metal, ceramic, inorganic polymer, etc.)
However, organic materials (low molecular weight, high molecular weight, etc.) and inorganic / organic composite materials can also be used. These protective films can be formed by various methods depending on the material used.

For example, the metal film is formed by plating (electrolytic plating, electroless plating, etc.), various thin film deposition techniques (vacuum vapor deposition, ion plating, sputtering, ion beam, etc.), Sn and Zn. It is possible to employ a method of immersing in a molten metal having a low melting point such as and cooling.

The film of the ceramic material may be formed by using a thin film deposition technique as in the case of the metal film. Alternatively, a treatment liquid in the case of utilizing the sol-gel method, an aqueous solution of alkali silicate or the like may be used and a dipping method or a spray method may be used. It may be formed using a method or the like. Alternatively, an electrophoretic electrodeposition method or the like may be adopted.

The resin film can be formed using an organic polymer material by various methods such as electrodeposition coating, spray coating, electrostatic coating, dip coating and roll coating. Also,
A film of an inorganic polymer material (for example, silicone resin) can be formed by the same method.

The protective film can also be formed using a low molecular weight organic material such as a coupling agent (silane type, titanate type, aluminate type, zirconate type) or benzotriazole. These low molecular weight organic materials are
It can be applied as a solution to the bonded magnet by various methods.

Fine particles are deposited (deposited) by various methods.
By doing so, a protective film can be formed. The fine particles include Al, Zn, Ni, Cu, Fe, Co, S
n, Pb, Au, Ag, etc., metal fine particles, SiO ₂ , A
Metal oxides and composite metal oxides (including glass) such as 1 ₂ O ₃ , ZrO ₂ , MgO, TiO ₂ , mullite, titanate, and silicate, TiN, AlN, BN, TiC, T.
Examples thereof include ceramic fine particles such as iCN and TiB ₂ , resin fine particles such as polytetrafluoroethylene and acrylic resin, carbon black and MoS ₂ .

A binder may be used if necessary in order to fix these fine particles to the surface of the bonded magnet. As the material of the binder, inorganic materials such as chromic acid, molybdic acid, phosphoric acid and salts thereof, low molecular weight organic compounds such as coupling agents, polymer compounds such as organic resins and the like can be used.

As a method of fixing the fine particles to the surface of the bond magnet, a mixture of fine particles and a binder may be applied by a coating method such as a spraying method or a dipping method. Alternatively, a binder previously formed on the surface of the bond magnet may be used. Fine particles may be attached to the layer by using mechanical force. If necessary, heat treatment may be performed to further firmly fix the fine particles to the surface of the bond magnet.

The protective film may be formed not only as a new film on the as-molded bond magnet but also by modifying the surface of the bond magnet. The reaction with the magnetic powder on the surface of the bonded magnet may be used. For example, various chemical conversion treatments such as phosphoric acid treatment, zinc phosphate treatment, manganese phosphate treatment, calcium phosphate treatment, phosphoric acid chromate treatment, chromic acid treatment, zirconic acid treatment, tungstic acid treatment and molybdic acid treatment can be mentioned. .

Since the content of the rare earth element (typically Nd) in the Ti-containing nanocomposite magnetic powder according to the present invention is low, sufficient corrosion resistance can be obtained even by using the chemical conversion treatment generally used in the field of steel. Can be obtained.

Further, the surface of the bonded magnet may be oxidized by various methods to form an oxide film having an appropriate thickness.

Further, as described above, since the bonded magnet of the present invention can essentially reduce voids, it has excellent corrosion resistance,
Moreover, although suitable for various surface treatments, various sealing treatments may be performed in order to further improve the reliability of the magnet when used in a harsh environment.

Further, the above-mentioned surface treatments may be combined appropriately, and for example, a laminated film may be formed by using different materials.

The thickness of the protective film is appropriately set according to the surface treatment method used and the application of the bond magnet, but the effect of improving energy efficiency by reducing the magnetic gap in the above-described motor is obtained. In order to obtain it, the thickness of the protective film is preferably 25 μm or less, more preferably 20 μm or less, still more preferably 10 μm or less.
μm or less.

[0200]

EXAMPLES First, Nd _8.5 Fe ₇₅ B ₁₁ Co ₂ C ₁ Ti
Purity 9 to have an alloy composition of _2.5 (atomic ratio)
9.5% or more of Nd, Fe, B, Co, C, and Ti
The raw material of Example 1 was weighed so that the total amount was 20 kg (kg), charged into a melting crucible, and then melted by high frequency melting. Then, the melting crucible was tilted, and the molten metal was poured into the tundish crucible which was kept at 1250 ° C. by a molybdenum heater. The tundish crucible has a diameter of 2.
Since it has a nozzle with a 0 mm orifice,
The molten alloy is discharged downward from the orifice nozzle.

The raw materials were dissolved by a high frequency heating method in an argon atmosphere with a pressure of 10 kPa. In this example, the molten metal temperature was set to 1400 ° C.

By pressing the molten alloy surface with argon gas of 6 kPa, 0.7 mm below the orifice.
The molten metal was ejected onto the outer peripheral surface of the copper roll at the position. The roll rotates at high speed while the inside is cooled so that the temperature of the outer peripheral surface is maintained at about room temperature. For this reason, the molten alloy ejected from the orifice comes in contact with the peripheral surface of the roll to remove heat and is blown in the circumferential velocity direction. Since the molten alloy is continuously ejected onto the peripheral surface of the roll through the orifice, the alloy solidified by the rapid cooling has the form of a ribbon elongated in the shape of a ribbon.

In the case of the rotating roll method (single roll method) adopted in this embodiment, the cooling rate is defined by the roll peripheral speed and the molten metal flow rate per unit time. This molten metal flow-down amount depends on the orifice diameter (cross-sectional area) and the molten metal pressure. In this embodiment, the flow rate is set to about 4 kg / min, the roll surface speed is set to 13 m / sec, and the average thickness is 63 μm.
A quenched alloy having a thickness of about 15 μm or less was prepared.

The quenched alloy thus obtained was roughly broken (coarsely crushed) by a crushing blade provided at the upper part of the recovery tank in the quenching apparatus, and then recovered. In this example, a crushing blade rotating at 1620 rpm was used to crush into pieces (flakes) having a size of 850 μm or less.

Next, using a rotary tube furnace whose heating part was filled with an argon atmosphere, a heat treatment was carried out by passing the heating zone kept at 740 ° C. for 20 minutes. Then, using a power mill, the quenched alloy after the heat treatment was pulverized under the conditions shown in Table 1 to obtain a nanocomposite magnet alloy powder.

[0206]

[Table 1]

"Punch metal screen aperture diameter" in Table 1 means the size of the opening in the screen provided around the crushing part (crushing blade) of the power mill. The particle size distribution of the obtained nanocomposite magnet alloy powder is shown in Table 2 and FIG.

[0208]

[Table 2]

[0209] In Table 2 and Fig. 10, for example, "<38" and "<106" indicate "particle size 3", respectively.
8 μm or less ”and“ particle size 106 μm or less ”.

As is apparent from FIG. 1
Nos. 3 to 3 have a bimodal particle size distribution in which the particle size has a first peak in the range of more than 106 μm and 300 μm or less, and has the second peak in the range of particle size of 106 μm or less. The term "bimodal particle size distribution" as used herein means that a valley exists in the particle size distribution, and the value of the valley bottom is 20% or less of the maximum peak value of the particle size distribution. Ratio (L _B ) of valley bottom value (L _B ) to maximum peak value (L _P )
_B / L _P) of the sample No. When calculated for 1 to 3, they are about 10%, about 7.5%, and about 4.5%, respectively. In addition, the particle size indicating the valley bottom of the particle size distribution is 53μ or more and 125μ
It exists in the range of m or less.

Next, the magnetic characteristics of each sample powder were measured using a vibrating magnetometer, and the magnetic characteristics shown in Table 3 below were obtained.

[0212]

[Table 3]

Further, 2% by weight of epoxy resin was added to the obtained magnet powder and mixed and kneaded to obtain a compound for compression molded bonded magnet. Then, a columnar compressed bond magnet having a diameter of 10 mm and a diameter of 7 mm was produced at a molding pressure of 10 t / cm ² . Table 4 shows the measured molding density and magnetic properties of this bonded magnet.

[0214]

[Table 4]

As can be seen from Table 4, the sample No. 1-3
In each case, a molding density of 6 g / cm ³ or more was obtained, and as a result, a high residual magnetic flux density B _{r of} 660 mT or more was obtained.

(Comparative Example 1) In Comparative Example 1, only the conditions for producing the quenched alloy were changed from the conditions in the examples.
Specifically, the roll surface speed during the quenching process is set to 20
It was set to m / sec and a quenched alloy having an average thickness of about 35 μm was produced. Other conditions are the same as those in the embodiment.

The power mill used in the examples was pulverized under the conditions shown in Table 1 to prepare magnet powder. The particle size distribution of the obtained magnet powder is shown in Table 2 above and FIG.
The magnetic properties are shown in Table 3. In Comparative Example 1, a clear bimodal particle size distribution was not obtained as compared with the Examples. In particular, the ratio of the value of the valley to the maximum peak value _{(L P) (L B)} (L B / L P) in the case of Comparative Example 1, about 23%,
It exceeds 20%.

Using the obtained magnet powder, a compression-molded bonded magnet was produced in the same manner as in Example 1. Table 4 shows the obtained molding density and magnetic properties.

As can be seen from Table 4, the molding density of the comparative example did not reach 6 g / cm ³ and the residual magnetic flux density B _r
Also, a high value of 660 mT or more was not obtained.

(Comparative Example 2) A quenched alloy (average thickness: about 63 μm) produced in the same manner as in Example was pulverized using a pin disk mill. The rotation speed of the pin disk mill is 50
It was set to 00 rpm. The particle size distribution of the obtained powder is shown in Table 5 below and FIG.

[0221]

[Table 5]

[0222] As is clear from FIG. 11, the particle size of the first peak is less than 106 [mu] m, moreover, the maximum peak value the value of the valley with respect to (L _P) ratio of _{(L B) (L B /} L P)
Is about 38% in the case of Comparative Example 1 and greatly exceeds 20%. When crushed with a pin mill, the particle size is 1
Percentage (weight ratio) of powder particles larger than 06 μm
Is less than 50% of the total. This deteriorates the filling property of the powder and thus lowers the molding density.

[0223]

EFFECTS OF THE INVENTION According to the present invention, a nanocomposite magnet alloy powder having excellent moldability can be provided without performing a special particle size distribution adjusting step after the pulverizing step.

The nanocomposite magnet alloy powder produced by the method of the present invention is a Ti-containing nanocomposite magnetic powder exhibiting excellent magnetic properties despite having a low rare earth element content, and a particle size excellent in formability. Since it has a distribution, a high-performance bonded magnet can be provided at low cost. Especially, for example, the outer diameter is 4 mm to 20 mm and the inner diameter is 2 m.
It is suitable for use in a small ring magnet having a thickness of m to 18 mm and a thickness of 0.5 mm to 2 mm, and can provide a small bond magnet with high performance and high reliability.

[Brief description of drawings]

FIG. 1A is a schematic view showing a configuration of a crushing device used in the present invention, and FIG. 1B is a perspective view showing an example of a screen used in the crushing device.

FIG. 2 is a graph showing the relationship between the maximum magnetic energy product (BH) _{max of an} Nd—Fe—B nanocomposite magnet to which Ti is not added and the boron concentration. In the graph, white bars represent data for samples containing 10-14 atomic% Nd, and black bars represent data for samples containing 8-10 atomic% Nd.

FIG. 3 is a graph showing the relationship between the maximum magnetic energy product (BH) _max and the boron concentration of the Nd-Fe-B nanocomposite magnet to which Ti is added. In the graph, white bars represent data for samples containing 10-14 atomic% Nd, and black bars represent data for samples containing 8-10 atomic% Nd.

FIG. 4 is a schematic diagram showing an R ₂ Fe ₁₄ B type compound phase and a (Fe, Ti) -B phase in a magnet according to the present invention.

FIG. 5 shows the case of adding Ti and N instead of Ti.
It is a figure which shows typically the change of the microstructure in the crystallization process of a rapidly solidified alloy when b etc. are added.

FIG. 6 (a) is a cross-sectional view showing an example of the overall configuration of an apparatus used in the method for producing a quenched alloy for iron-based rare earth alloy magnets according to the present invention, and FIG. 6 (b) is a rapid solidification process. It is an enlarged view of a part.

FIG. 7 is a cross-sectional view showing an example of the overall configuration of a strip casting apparatus used in a method for producing a quenched alloy.

8 is a diagram showing a configuration of a chute that is preferably used in the apparatus of FIG.

9 (a) is a perspective view schematically showing an alloy before crushing and powder particles after crushing according to the present invention, and FIG.
FIG. 3 is a perspective view schematically showing an alloy before crushing and powder particles after crushing in the related art.

FIG. 10 is a histogram showing the particle size distribution of the magnetic particles of the example (Material Nos. 1 to 3) of the present invention and Comparative Example 1 (Material No. 4).

11 is a histogram showing a particle size distribution of magnetic powder of Comparative Example 2. FIG.

[Explanation of symbols]

1b, 2b, 8b, and 9b Atmospheric gas supply port 1a, 2a, 8a, and 9a gas outlets 1 Melting chamber 2 quenching room 3 melting furnace 4 Hot water storage container 5 Hot water nozzle 6 funnel 7 rotating cooling rolls 21 molten metal 22 Alloy ribbon 23 molten alloy 23a Strip-shaped solidified alloy 30 main chamber 32 melting furnace 34 cooling roll 36 Shoots (Tundish) 40 Recovery means 42 rotating blade 44 Guide member 48 shutters 50 sub chambers 100 crushing blade 102 Screen with openings

─────────────────────────────────────────────────── ─── Continued Front Page (51) Int.Cl. ⁷ Identification Code FI Theme Coat (Reference) B22F 3/02 B22F 3/02 G 9/04 9/04 C E C22C 1/00 C22C 1/00 A 1 / 02 501 1/02 501 503 503Z 38/00 303 38/00 303D 38/60 38/60 45/02 45/02 A H01F 1/053 H01F 1/08 A 1/08 41/02 G 41/02 1 / 04 HF term (reference) 4K017 AA01 AA04 BA06 BB01 BB02 BB04 BB05 BB06 BB07 BB08 BB09 BB13 CA07 DA02 DA04 EA03 EE01 FA04 4K018 AA27 BA18 BB04 BB06 BB06 BB06A01 B01A01 B01A01 B01A01 B01A01B01A01 5A19 B01A01 5A040 ABB01 5A040 ABB01 BB46A19A01 AA01 AA04 BA06 ABB04A01 AA01 AA04 BA06 BB06A01A02 ABB01 BB06B17A01B01A17B01A17A01A02 CD05 CE04 CE05 CG03

Claims (11)

[Claims] 1. The composition formula is (Fe _1-m T _m ) _100-xyz Q _x R
_y Ti _z M _n (T is one or more elements selected from the group consisting of Co and Ni, Q is one or more elements selected from the group consisting of B and C, and always contains B, and R is La and C
at least one rare earth metal element substantially free of e, M is Al, Si, V, Cr, Mn, Cu, Zn, Ga, Z
r, Nb, Mo, Hf, Ta, W, Pt, Pb, Au and Ag, and the composition ratios x, y, z, n and m are represented by at least one metal element selected from the group consisting of:
Respectively, 10 <x ≦ 20 atomic%, 6 ≦ y <10 atomic%, 0.1 ≦ z ≦ 12 atomic%, 0 ≦ n ≦ 10 atomic%,
And a step of preparing a quenched alloy satisfying 0 ≦ m ≦ 0.5 and having an average thickness of more than 40 μm and 90 μm or less; A crushing step of crushing the quenched alloy using a crusher equipped with a screen to produce an alloy powder having a particle size smaller than the opening of the screen. 2. A particle size of 106 μm in the crushing step.
has a first peak in a range of more than m and 300 μm or less, and
The method for producing a nanocomposite magnet powder according to claim 1, wherein an alloy powder having a particle size distribution having a second peak in a particle size range of 106 μm or less is prepared. 3. The step of preparing the quenched alloy includes the step of preparing a melt of the alloy represented by the composition formula, and the step of preparing the melt of the alloy on the surface of a rotating cooling roll.
Contact was made at a feed rate of 5 kg / min or more, whereby the crystalline phase of the R ₂ T ₁₄ Q type compound was 50% by volume of the whole.
The manufacturing method of the nano composite magnet powder of Claim 1 or 2 including the cooling process which produces the quenching alloy containing the above. 4. A magnetically-coupled R ₂ T ₁₄ Q-type compound and a ferromagnetic iron-based boride are contained, and the volume ratio of all crystalline phases is 95% or more of the whole, and amorphous. The method for producing a nanocomposite magnet powder according to claim 1, wherein the volume ratio of the phase is 5% or less of the whole. 5. The volume ratio of the R ₂ T ₁₄ Q type compound is
It is 65% or more and 85% or less of the whole, The manufacturing method of the nano composite magnet powder of Claim 4. 6. The ferromagnetic iron-based boride is the R ₂ T ₁₄
The method for producing the nanocomposite magnet powder according to claim 1, wherein the nanocomposite magnet powder is present in the grain boundary of the Q-type compound. 7. The average crystal grain size of the R ₂ T ₁₄ Q type compound is in the range of 10 nm to 200 nm, and the average grain size of the ferromagnetic iron-based boride is in the range of 1 nm to 100 nm. A method for producing the nanocomposite magnet powder described. 8. An average size of 1 is obtained by roughly crushing the quenched alloy before the step of producing the alloy powder.
The method for producing a nanocomposite magnet powder according to any one of claims 1 to 7, comprising a step of producing a coarsely pulverized powder having a size of not more than mm. 9. The method according to claim 8, further comprising a heat treatment step of heating the coarsely pulverized powder of the quenched alloy or the alloy powder at a temperature of 500 ° C. to 900 ° C. for 10 seconds or more after the step of producing the coarsely pulverized powder. A method for producing the nanocomposite magnet powder described. 10. The crushing device is a power mill or a feather mill in which the size of the opening of the screen is set in the range of more than 200 μm and 1.0 mm or less.
10. The method for producing the nanocomposite magnet powder according to any one of 1 to 9. 11. A step of preparing a nanocomposite magnet powder manufactured by the method according to claim 1, wherein the nanocomposite magnet powder is compression-molded to obtain 6.0 g.
/ Cm ³ or more, a step of producing a molded body having a density of not less than / cm ³ , and a method for producing a bonded magnet.