JP2002285301A - Iron and rare earth based permanent magnet alloy and production method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce an iron and rare earth based permanent magnet alloy which can relatively inexpensively be produced, and has excellent magnetic properties. SOLUTION: In the iron and rare earth based permanent magnet alloy, the compositional formula is expressed by (Fe1-k Tk )100-x-y-z Qx (Nd1-m R1m )y Mz (wherein, T is one or two kinds of elements selected from the groups consisting of Co and Ni; Q is one or two kinds of elements selected from the groups consisting of B and C; R1 is one or more kinds of elements selected from the groups consisting of Y, Ce and La; and M is one or more kinds of elements selected from the groups consisting of Al, Si, Ti, V, Cr, Mn, Cu, Zn, Ga, Zr, Nb, Mo, Ag, Hf, Ta, W, Pt, Au and Pb); and, (x), (y), (z), (k) and (m) respectively satisfy 10<x<=25 atomic %, 2<=y<=9.5 atomic %, 0<=z<=10 atomic %, 0<=k<=0.5, and 0<m<=0.15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an iron-based rare earth permanent magnet alloy containing Nd and a method for producing the same.
The present invention relates to a rare earth permanent magnet alloy containing a rare earth element other than d as an impurity.

[0002]

2. Description of the Related Art In recent years, higher performance, smaller size and lighter weight have been demanded for home electric appliances, OA equipment, electric components and the like. Therefore, for the permanent magnets used in such equipment, it is required to maximize the performance-to-weight ratio of the entire magnetic circuit, for example remanence B _r is 0.5 T (tesla) or more permanent It is required to use a magnet. However, by conventional relatively inexpensive hard ferrite magnets, the residual magnetic flux density B _r 0.
It cannot be more than 5T.

At present, a high residual magnetic flux density B of 0.5 T or more
_As a permanent magnet having _r , an Sm-Co-based magnet manufactured by a powder metallurgy method is known. Except for Sm-Co magnets, Nd-F produced by powder metallurgy
e-B magnets and Nd-
The Fe-B quenched magnet exhibits a high residual magnetic flux density _Br . The former Nd-Fe-B based magnet is disclosed in
No. 46008 discloses the latter Nd-F
An eB-based quenched magnet is disclosed in, for example, JP-A-60-9852. Nd-Fe-B magnets are inexpensive F
e-based rare earth alloy magnet containing e
-It can be manufactured cheaply as compared with a Co-based magnet.

As an Nd—Fe—B magnet, a composition having a relatively low rare earth element concentration, that is, Nd _3.8 Fe
A magnet material having a composition near _77.2 B ₁₉ (at.%) And having a main phase of Fe ₃ B type compound is known (R. Coehoorn).
Et al., J. de Phys, C8, 1998, 669-670). This permanent magnet material is obtained by subjecting an amorphous alloy produced by a liquid quenching method to a crystallization heat treatment, whereby a fine crystal aggregate in which a soft magnetic Fe ₃ B phase and a hard magnetic Nd ₂ Fe ₁₄ B phase are mixed. It has a metastable structure formed from a body and is called a “nanocomposite magnet”. Such nanocomposite magnet has been reported to have a high residual magnetic flux density B _r of more than 1T,
Its coercive force H _cJ is relatively low, from 160 kA / m to 240 kA / m. Therefore, the use of this permanent magnet material is limited to applications where the operating point of the magnet is one or more.

[0005]

As described above, Nd-
The Fe-B-based magnet can be manufactured at a lower cost than the Sm-Co-based magnet, but has a problem that the cost required for the manufacturing process of the Nd-Fe-B-based magnet is high. One of the reasons for the high cost of the production process is that large-scale equipment and a large number of steps are required for the separation and purification of Nd and the reduction reaction.

In the case of manufacturing the above-described nanocomposite magnet, a high-purity (for example, 99.8% pure) Nd material is often used as a material containing a rare earth element. The reason for using such a high-purity Nd material is that Nd, which is essential for forming the Nd ₂ Fe ₁₄ B phase, is used.
If impurities such as other rare earth elements (for example, La and Ce) are included in the material in addition to d, the magnetic properties (such as coercive force H _CJ ) of the obtained magnet alloy may be significantly reduced. It is. In particular, when the amount of Nd is relatively small, that is, 9.5 atomic% or less, the coercive force is significantly reduced when La or Ce is contained. Therefore, Nd-Fe alloy,
Although a dymium alloy containing Nd and Pr may be used, use of a material containing La or Ce has been generally avoided as much as possible.

On the other hand, when producing a nanocomposite magnet, La having excellent amorphous forming ability is added to a raw material alloy, and the molten metal of the raw material alloy is rapidly cooled to produce a rapidly solidified alloy having an amorphous phase as a main phase. Then, both a Nd ₂ Fe ₁₄ B phase and an α-Fe phase are precipitated and grown by a crystallization heat treatment, and a technique for making each phase finer to about several tens of nm has been reported (WCChan, e).
t.al. "THE EFFECTS OFREFRACTORY METALS ON THE MAGN
ETIC PROPERTIES OFα-Fe / R ₂ Fe ₁₄ B-TYPE NANOCOMPOSITE
S ", IEEE, Trans. Magn. No. 5, INTERMAG. 99, Kyongi
u, Korea pp. 3265-3267, 1999). However, in this paper, the composition ratio of Nd which is a rare earth element is set to 9.5a.
It is possible to increase Nd ₂ F to 11.0 at% from t%.
It is taught that it is preferable in miniaturizing both the e ₁₄ B phase and the α-Fe phase. In other words, when a predetermined amount of La is added for the purpose of improving the ability to form an amorphous phase, an Nd-Fe-B-based permanent magnet having desired magnetic properties can be obtained while keeping the amount of Nd relatively small. It was difficult to make an alloy. When the amount of Nd is increased, there is a problem that the manufacturing cost increases.

The present invention has been made in view of the above points, and a main object of the present invention is to provide a Nd-Fe-B-based permanent magnet alloy having excellent magnetic properties which can be manufactured at a relatively low cost. It is in.

[0009]

The iron-based rare earth permanent magnet alloy according to the present invention has a composition formula of (Fe _1-k T _k ) _{100-xy- z.
Q x (Nd 1-m R1} m) y M z ( where, T is one or two elements selected from the group consisting Co, and Ni, Q is, B
Or one or two elements selected from the group consisting of C, R1 is one or more elements selected from the group consisting of Y, Ce, and La, and M is Al, Si, Ti, V, C
r, Mn, Cu, Zn, Ga, Zr, Nb, Mo, A
g, Hf, Ta, W, Pt, Au, Pb), x, y, z,
k and m are respectively 10 <x ≦ 25 atomic%, 2 ≦
y ≦ 9.5 atomic%, 0 ≦ z ≦ 10 atomic%, 0 ≦ k ≦ 0.
5 and 0 <m ≦ 0.15.

[0010] In a preferred embodiment, m is equal to 0.
It satisfies 01 ≦ m ≦ 0.15.

In a preferred embodiment, the M is Ti
Must be included.

In a preferred embodiment, the composition ratio of Ti is 0.5 atom% or more and 7.0 atom% or less.

In a preferred embodiment, a rare earth element R2 of a different type from the rare earth element R1 (where R2 is
One or more of Pr, Dy, and Tb), and the composition formula is (Fe _1-k T _k ) _100-xyz Q _x (Nd
_1-mn R1 _m R2 _n ) _{y Mz} , where n is 0 <n ≦ 0.2
5 is satisfied.

In a preferred embodiment, m and n satisfy 0 <m + n ≦ 0.25.

In the method for producing an iron-based rare earth permanent magnet alloy according to the present invention, the composition formula is (Fe _{1 -kT k} ) _{100 -xyz} Q _x (Nd
_1-m R1 _m ) _y M _z (where T is one or two elements selected from the group consisting of Co and Ni, and Q is one or two elements selected from the group consisting of B or C) Element of R1,
Is 1 selected from the group consisting of Y, Ce, and La
M or more elements, M is Al, Si, Ti, V, Cr, M
n, Cu, Zn, Ga, Zr, Nb, Mo, Ag, H
f, Ta, W, Pt, Au, and Pb), wherein x, y, z, k, and m are each 10 <x ≦ 25 at%, 2 ≦ y ≦ 9.
5 atomic%, 0 ≦ z ≦ 10 atomic%, 0 ≦ k ≦ 0.5, 0 <
preparing a melt of the iron-based rare earth material alloy satisfying m ≦ 0.15; supplying the melt of the alloy onto guide means; forming a lateral flow of the melt of alloy on the guide means; Moving the alloy melt to a contact area with a cooling roll, and quenching the alloy melt with the cooling roll to produce a quenched alloy containing a Nd ₂ Fe ₁₄ B type compound phase.

The rare earth magnet of the present invention is produced by subjecting an iron-based rare earth permanent magnet alloy produced by the above production method to a crystallization heat treatment.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventor has proposed a ferromagnetic N
In an iron-based rare earth permanent magnet alloy in which an iron-based boride phase and an α-Fe phase, which are ferromagnetic similarly to the d ₂ Fe ₁₄ B-type compound phase, are mixed in the same metallographic structure, impurities other than Nd, which are essential, The permissible concentration of rare earth elements that may be mixed in as an element was studied. As a result, assuming that the maximum energy product (BH) _max in the case of the total amount Nd is 100%, in order to suppress the reduction rate of the maximum energy product (BH) _max to within 20%, the rare earth impurities (Y , La, Ce) were found to be required to be within 15%, thereby completing the present invention.

According to the present invention, the composition formula is (Fe _1-k T _k )
_100-xyz Q _x (Nd _1-m R1 _m ) _y M _z (where T is Co,
One or two elements selected from the group consisting of Ni,
Q is one or two elements selected from the group consisting of B or C; R1 is one or more elements selected from the group consisting of Y, Ce, and La; and M is Al, Si, T
i, V, Cr, Mn, Cu, Zn, Ga, Zr, Nb,
One or more elements selected from the group consisting of Mo, Ag, Hf, Ta, W, Pt, Au, and Pb), x,
y, z, k, and m are respectively 10 <x ≦ 25 atomic% (at%), 2 ≦ y ≦ 9.5 atomic%, 0 ≦ z ≦ 10 atomic%, 0 ≦ k ≦ 0.5, 0 An iron-based rare earth permanent magnet alloy that satisfies <m ≦ 0.15 is provided.

The most characteristic point of the present invention is that in a rare-earth magnet alloy having a relatively small amount of Nd of 9.5 at% or less, one kind selected from the group consisting of Y, Ce and La as the rare-earth impurity R1. When the above element R1 is mixed, its content is suppressed to 15 at% or less as a ratio to the total rare earth element R amount including Nd.
The iron-based rare-earth permanent magnet alloy of the present invention contains the above-mentioned rare-earth impurity R1, but the amount thereof is one of the total amount of the rare-earth elements.
Since it is relatively small at 5 at% or less, the reduction rate of the maximum energy product (BH) _max is 20% as compared with the case where the total amount is Nd.
It can be suppressed to the extent. Further, the iron-based rare earth permanent magnet alloy of the present invention has a relatively small amount of Y, Ce,
And La may be contained, and a Nd-Fe-B-based magnet alloy having high magnetic properties can be manufactured without using a high-purity Nd material.

The rare earth permanent magnet alloy of the present invention can be manufactured using a low-purity Nd-containing material which can be obtained relatively inexpensively as a raw material of Nd. For example, misch metal is known to contain La and Ce in addition to Nd. However, if the amount of La and Ce is 15 at% or less of the total amount of rare earth elements including Nd, purification of Nd is necessary. This can be used without losing it. Further, even when the misch metal contains a relatively large amount of La or Ce, by using it in combination with a higher-purity Nd material,
If the total amount of Ce and Ce is adjusted to 15 at% or less of the total amount of the rare-earth element as a whole, a rare-earth magnet alloy having desired magnetic characteristics can be produced using the Nd without purifying Nd. Can be. This makes it possible to significantly reduce manufacturing costs.

In the case where the nanocomposite magnet is manufactured by the liquid quenching method, if the amount of rare earth impurities such as La and Ce increases, the coercive force H _CJ decreases and the squareness of the demagnetization curve decreases. . In particular, when a predetermined amount (for example, 0.5 to 7.0 at%) of Ti is added as the additional element M, it is important to set the amounts of La and Ce within a predetermined range. Hereinafter, Nd-Fe containing Ti
The -B system magnet will be described.

In order to make the molten Nd-Fe-B rare earth alloy amorphous at a relatively slow cooling rate, it is desirable to add B (boron) in an amount of more than 10 atomic%.
This is because B has the effect of increasing the ability of the alloy to produce amorphous. However, when B is added in such a large amount, the amorphous phase present in the quenched alloy inevitably contains B in excess, and this B is combined with other elements in the subsequent crystallization heat treatment to precipitate.・ It is thought that it will grow easily. As described above, when B contained in the amorphous phase before the heat treatment is combined with another element to generate a boride having a low magnetization, the B remains low even after the crystallization heat treatment.
Since a high-concentration nonmagnetic amorphous phase remains in the metal structure and a uniform fine crystal structure cannot be obtained, the magnetization of the magnet as a whole decreases.

On the other hand, when Ti is added, unlike the case where other kinds of metals such as V, Cr, Mn, Nb, and Mo are added instead of Ti, the magnetization does not decrease.
Rather, the magnetization is improved. Also, when Ti is added, the squareness of the demagnetization curve becomes particularly good as compared with the other additional elements described above. This increase in magnetization causes the formation of a boride phase such as a ferromagnetic iron-based boride from the boron-rich non-magnetic amorphous phase present in the rapidly solidified alloy by the action of Ti, and the non-magnetic amorphous phase remaining after the crystallization heat treatment. It is believed that this was obtained because the volume ratio of the phases was reduced.

Particularly, when B and Ti are relatively small in the composition range of the magnet alloy, a ferromagnetic iron-based boride phase is liable to be precipitated by the heat treatment. In this case, B contained in the non-magnetic amorphous phase is taken into the iron-based boride, so that the volume ratio of the non-magnetic amorphous phase remaining after the crystallization heat treatment decreases and the ferromagnetic crystal phase increases. Therefore, the residual magnetic flux density _Br is improved.

When Ti is added, α-Fe precipitates
Growth of each constituent phase in the temperature range higher than
Is suppressed, and excellent hard magnetic properties are exhibited. And
Nd _TwoFe₁₄Generates ferromagnetic phases other than B phase and α-Fe phase
Thereby containing three or more ferromagnetic phases in the alloy.
Can be formed. N instead of Ti
When metal elements such as b, V, and Cr are added, α-F
α-Fe phase in a relatively high temperature range where e phase precipitates
Of the α-Fe phase is hard magnetic.
A bond that is not effectively restrained by exchange coupling with the sexual phase
As a result, the squareness of the demagnetization curve is greatly reduced.

When Nb, Mo, and W are added without adding Ti, if a heat treatment is performed in a relatively low temperature range where α-Fe does not precipitate, a good hardened steel having excellent demagnetization curve squareness can be obtained. Although it is possible to obtain magnetic properties, it is presumed that the R ₂ Fe ₁₄ B type fine crystal phase is dispersed and present in the non-magnetic amorphous phase in the alloy that has been heat-treated at such a temperature. No nanocomposite magnet configuration is formed. When heat treatment is performed at a higher temperature, an α-Fe phase is precipitated from the amorphous phase. Unlike the case where Ti is added, the α-Fe phase grows rapidly after precipitation and becomes coarse. For this reason, the magnetization direction of the α-Fe phase is not effectively restricted by exchange coupling with the hard magnetic phase,
The squareness of the demagnetization curve will be greatly deteriorated.

Only when Ti is added, α-
The coarsening of the Fe phase can be appropriately suppressed, and a ferromagnetic iron-based boride can be formed. Further, Ti is an element that delays the crystallization of primary Fe crystals (γ-Fe which later transforms to α-Fe) during liquid quenching and facilitates generation of a supercooled liquid.
In addition, it is important to precipitate α-Fe even if the cooling rate for rapidly cooling the molten alloy is set to a relatively low value of about 1 × 10 ³ ° C./sec to 8 × 10 ⁴ ° C./sec. In addition, it is possible to produce a quenched alloy in which an R ₂ Fe ₁₄ B type crystal phase and an amorphous phase are mixed. This means
Among various liquid quenching methods, it is important for cost reduction to enable adoption of a strip casting method particularly suitable for mass production.

Thus, when Ti is added,
It is possible to mass-produce permanent magnets having high magnetization (residual magnetic flux density) and coercive force and excellent squareness of a demagnetization curve while using a raw material alloy having a relatively small amount of rare earth elements (9.5 at% or less). .

When Ti is contained, a compound in which Ti and B are bonded (such as TiB ₂ ) is easily formed in the molten metal. As a result, the liquidus temperature of the molten metal is reduced to an iron-based rare earth magnet having a conventional composition. It is higher than the melt of the raw material alloy. On the other hand, if C (carbon) is added, the liquidus temperature of the molten alloy decreases, so that even if the tapping temperature is lowered, the viscosity of the molten metal hardly increases. Therefore, when producing a quenched alloy by the strip cast method, etc.,
It is possible to perform stable tapping continuously. When the tapping temperature is lowered, sufficient cooling can be achieved on the surface of the cooling roll, so that winding around the roll can be prevented and the rapidly solidified alloy structure can be uniformly refined.

As described above, Nd-Fe-B containing Ti
-Based magnet alloys have relatively small amounts of rare earth elements (9.5
(at% or less) A permanent magnet having high magnetization (residual magnetic flux density) and coercive force and excellent demagnetization curve squareness can be mass-produced using a raw material alloy. Therefore, in a preferred embodiment of the present invention, the magnet alloy includes Ti as an additional element. In the case where Ti is contained, even if a rare earth impurity R1 selected from the group consisting of Y, La and Ce is mixed, if the amount is 15 at% or less of the entire rare earth element, it is excellent in magnetic properties suitable for practical use. It is possible to produce a permanent magnet. According to the experiments of the present inventors, the effect of improving the magnetic properties obtained by adding Ti as described above is as follows.
It was found that La and Ce greatly reduced the value. Therefore, when Ti is added, it is particularly important to control the amounts of La and Ce.

[Reason for Limiting Composition] The rare earth magnet alloy of the present invention essentially contains Nd as the rare earth element R, and has a specific range of the amount of Y, La, and R as the rare earth impurity R1.
Including Ce. Furthermore, as another type of rare earth impurity R2, a specific range of amounts of Pr, Tb, and Dy may be included. Nd and rare earth impurities (R1 or R1 and R1
2) and the amount of the rare earth element R is 2a in composition ratio
If it is less than t%, the compound phase having the Nd ₂ Fe ₁₄ B type crystal structure is not sufficiently precipitated, so that hard magnetic properties cannot be obtained. On the other hand, if the amount of the rare earth element R exceeds 9.5 at% in composition ratio, iron and iron-based borides do not precipitate, so that a nanocomposite structure is not obtained and high magnetization cannot be obtained. Therefore, the composition ratio of the rare earth element R is set to 2 at% or more and 9.5 a
Set to the range of t% or less. Preferably, it is 3 at% or more and 9.5 at% or less. More preferably, it is 4 at% or more and 9.2 at% or less.

Rare earth impurity R1 for all rare earth elements R
When the content of (Y, La, Ce) exceeds 15 at%, H
_{Since cJ} is greatly reduced, its content must be 15 at% or less. That is, the rare earth element R in the alloy
Is represented by (Nd _1-m R1 _m ), 0 <m ≦ 0.15
Meet. In order to reduce the manufacturing cost, as long as the desired magnetic characteristics can be obtained, the rare-earth impurity R1
May be large. Even without using high purity Nd material,
This is because a relatively inexpensive material such as misch metal can be used. Therefore, the above m is 0.01 ≦
m ≦ 0.15 may be satisfied. In order to produce a magnet alloy at a lower cost, m is 0.05 ≦ m ≦ 0.
It may be 15.

The rare earth impurity R2 (Pr, Tb, D
In the case of containing y), if the content of R2 with respect to all the rare earth elements R exceeds 25 at%, the squareness of the demagnetization curve is greatly deteriorated, and the maximum energy product (BH) _max when the total amount is Nd.
(BH) _max is reduced by 20% or more. For this reason,
The content of the rare earth impurity R2 with respect to the total rare earth concentration is 25.
It is desirable that it is within at%. That is, when the rare earth element R in the alloy is represented by (Nd _{1- mn} R1 _m R2 _n ), it is desirable that 0 <n ≦ 0.25 be satisfied. Also,
The content of the rare earth impurity R2 is within 20 at% (n ≦ 0.
In the case of (20), _HcJ of Tb and Dy can be improved without significant deterioration of the squareness of the demagnetization curve. As long as the content of the rare earth impurity R2 is adjusted to 25 at% or less, desired magnetic characteristics can be obtained by using a relatively low-purity Nd material (for example, a didymium alloy containing Pr as an impurity other than Nd). Can be produced. From the perspective of reducing manufacturing costs,
The content n of R2 is preferably 0.05 ≦ n ≦ 0.25, and more preferably 0.1 ≦ n ≦ 0.25.

When the total amount of the rare earth impurities R1 and R2 is larger than the amount of Nd, it is impossible to produce a magnet alloy having magnetic properties suitable for practical use. For this reason, R1 and R1 relative to the total amount of the rare earth element R
The content m + n of 2 is desirably 0 <m + n ≦ 0.25. From the viewpoint of reducing manufacturing costs, it is more preferable that 0.1 ≦ m + n ≦ 0.25.

When B is less than 10 at%, amorphousization is not promoted when a liquid quenching method is used, or a nano-order uniform fine crystal structure cannot be obtained. As a result, after the optimal crystallization heat treatment, a nanocomposite structure having a good demagnetization curve squareness is not formed, and excellent hard magnetic properties cannot be obtained. On the other hand, if the composition ratio of B exceeds 25 at%, the Nd ₂ Fe ₁₄ B type compound phase does not precipitate and hard magnetic properties cannot be obtained. Therefore, the composition ratio of B is 10 at%.
It is set to be larger than 25 at% or less. Preferably, it is set to be greater than 10 at% and equal to or less than 20 at%, and more preferably 10.5 at% to 2 at%.
It is better to set it in the range of 0 at% or less. In addition, 5 of B
Up to 0% may be replaced by C, in which case the magnetic properties and metallographic structure are not affected.

Although Fe substantially occupies the balance of the above-mentioned elements, desired hard magnetic properties can be obtained even if a part of Fe is replaced with one or two of Co and Ni. However, since the amount of substitution for Fe may not be able to obtain a residual magnetic flux density B _r of more than 0.5T more than 50%
The substitution amount is limited to a range of 0% to 50%. still,
By substituting Co, H _cJ is improved and Nd ₂
By increasing the Curie temperature of the Fe ₁₄ B phase, heat resistance is improved. The preferred range of this substitution amount is 0.5% or more and 1% or more.
5% or less.

As the additive element M, Al, Si, T
i, V, Cr, Mn, Cu, Zn, Ga, Zr, Nb,
By adding one or more elements of Mo, Ag, Hf, Ta, W, Pt, Au, and Pb, the magnetic properties are improved and the effect of expanding the optimum heat treatment temperature range is obtained. If the composition ratio of the element M exceeds 10 at%, the magnetization is reduced, so that the content is limited to 0 at% or more and 10 at% or less. Preferably, it is set to 0.1 at% or more and 5 at% or less. In a preferred embodiment, the additive element M always contains Ti, but the composition ratio of Ti is 0.5 at% or more and 7.0 or more.
At% or less is desirable.

Hereinafter, one embodiment of the present invention will be described. In the present embodiment, for example, an Nd—Fe—B-based magnet alloy having the above composition is manufactured using the quenching device shown in FIG.
In order to prevent oxidation of a magnetic alloy containing Nd or Fe which is easily oxidized, an alloy manufacturing process is performed in an inert gas atmosphere. As the inert gas, a rare gas such as helium or argon or nitrogen can be used. Note that since nitrogen is relatively easily reacted with Nd, it is preferable to use a rare gas such as helium or argon.

[Liquid quenching apparatus] The apparatus shown in FIG. 1 is provided with a raw material alloy melting chamber 1 and a quenching chamber 2 capable of maintaining a vacuum or inert gas atmosphere and adjusting the pressure. FIG. 1A is an overall configuration diagram, and FIG. 1B is a partially enlarged view.

As shown in FIG. 1A, the melting chamber 1
Is a raw material 2 blended to have a desired magnet alloy composition.
Melting furnace 3 for dissolving 0 at high temperature, and tapping nozzle 5 at the bottom
And a mixing raw material supply device 8 for supplying the mixing 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) that stores the molten metal 21 of the raw material alloy and can maintain the temperature of the molten metal at a predetermined level.

The quenching chamber 2 contains the molten metal 2 discharged from the tapping nozzle 5.
1 is provided with a rotary cooling roll 7 for rapidly cooling and solidifying 1.

In this apparatus, the atmosphere and the pressure in the melting chamber 1 and the quenching chamber 2 are controlled within a predetermined range. For this purpose, the atmosphere gas supply ports 1b, 2b, and 8b and the gas exhaust ports 1a, 2a, and 8a are provided at appropriate locations in 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 a range of 30 kPa to normal pressure (atmospheric pressure).

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

The tapping nozzle 5 of the hot water storage container 4 is disposed on a 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 provided.
Flow down to the surface of the cooling roll 7 located below. The orifice diameter of the tapping nozzle 5 is, for example, 0.5 to 2.0 m.
m. When the viscosity of the molten metal 21 is large, the molten metal 21 does not easily flow in the tapping nozzle 5. However, in this embodiment, since the quenching chamber 2 is maintained at a lower pressure state than the melting chamber 1, the melting chamber 1 and the quenching chamber 2 A pressure difference is formed between the
The hot water is run smoothly.

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 releasability of the quenched alloy from the cooling roll deteriorates, and the quenched alloy may be wound around the roll, which is not preferable. The 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 hot water per unit time.

According to the apparatus shown in FIG.
kg of the raw material alloy can be rapidly solidified in 10 to 20 minutes. The quenched alloy thus formed is, for example, an alloy ribbon (alloy ribbon) 22 having a thickness of 10 to 300 μm and a width of 2 mm to 3 mm.

[Liquid quenching method] First, a molten metal 21 of a raw material alloy represented by the above composition formula is prepared and stored in the hot water storage container 4 of the melting chamber 1 of the liquid quenching apparatus shown in FIG. Next, the melt 21 is poured from the tapping nozzle 5 onto the water-cooled roll 7 in a reduced-pressure Ar atmosphere, rapidly cooled by contact with the cooling roll 7, and solidified. As the rapid solidification method, it is necessary to use a method capable of controlling the cooling rate with high accuracy.

In the case of the present embodiment, when cooling and solidifying the molten metal 21, the cooling rate is preferably set to 1 × 10 ² to 1 × 10 ⁸ ° C./sec, preferably 1 × 10 ⁴ to 1 × 10 ⁶ ° C./sec. More preferably,

The time during which the molten alloy 21 is cooled by the cooling roll 7 corresponds to the time from contact of the alloy with the outer peripheral surface of the rotating cooling roll 7 until it leaves the alloy, during which time the temperature of the alloy decreases. , And becomes a supercooled liquid state. Thereafter, the supercooled alloy leaves the cooling roll 7 and flies in an inert atmosphere. The alloy is deprived of heat by the ambient gas while flying in the form of a ribbon, which further reduces its temperature. In the present embodiment, the pressure of the atmosphere gas is 30 kPa to
Since the pressure is set within the normal pressure range, the heat removal effect by the atmospheric gas is enhanced, and the Nd ₂ Fe ₁₄ B type compound can be uniformly and finely deposited and grown in the alloy. When an appropriate amount of Ti is added to the raw material alloy, α-Fe does not preferentially precipitate and grow in the quenched alloy that has undergone the above-described cooling process, so that the final magnet properties are improved. I do.

In this embodiment, the roll surface speed is 10 m
The average particle size is adjusted by adjusting the gas pressure within the range of 30 m / sec to 30 m / sec, and by increasing the ambient gas pressure to 30 kPa or more to enhance the secondary cooling effect of the ambient gas.
A quenched alloy containing a fine R ₂ Fe ₁₄ B-type compound phase of not more than nm is manufactured.

The quenching method of the molten alloy is not limited to the one-roll method described above, but is a twin-roll method, a gas atomizing method, a strip casting method in which a flow rate is not controlled by a nozzle or an orifice, and a roll method. And a cooling method combining the gas atomizing method and the like.

Among the above quenching methods, the cooling rate of the strip casting method is relatively low, and is 1 × 10 ³ to 8 × 10 ⁴ ° C. /
Seconds. If an appropriate amount of Ti is added to the alloy,
Even in the case of the strip casting method, it is possible to form a quenched alloy in which the structure not containing the primary Fe crystal is dominant. Since the process cost of the strip casting method is about half or less of that of other liquid quenching methods, it is more effective for producing a large amount of rapidly cooled alloy than the single roll method, and is a technique suitable for mass production. When Ti is not added to the raw material alloy, or when Cr, V, Mn, Mo, Ta, and / or W is added instead of Ti, a quenched alloy may be formed using a strip casting method. Since a metal structure containing a large amount of Fe primary crystals is generated, a desired metal structure cannot be formed.

[Heat Treatment] In this embodiment, the heat treatment is performed in an argon atmosphere. Preferably, the heating rate is 5 ° C.
After holding at a temperature of 550 ° C. or more and 850 ° C. or less for 30 seconds or more and 20 minutes or less, the temperature is cooled to room temperature. By this heat treatment, fine crystals of the metastable phase precipitate and grow in the amorphous phase, and a nanocomposite structure is formed. In the present embodiment, since the fine Nd ₂ Fe ₁₄ B-type crystal phase already exists at the start of the heat treatment, coarsening of the α-Fe phase and other crystal phases is suppressed,
Each constituent phase (soft magnetic phase) other than the Nd ₂ Fe ₁₄ B type crystal phase is uniformly refined.

When the heat treatment temperature is lower than 550 ° C.,
Many amorphous phases remain even after the heat treatment, and the coercive force may not reach a sufficient level depending on the quenching condition.
Further, when the heat treatment temperature exceeds 850 ° C., the grain growth of the respective constituent phases is significantly reduced residual magnetic flux density B _r, is deteriorated squareness of the demagnetization curve. Therefore, the heat treatment temperature is preferably 550 ° C. or more and 850 ° C. or less, and a more preferable heat treatment temperature is 570 ° C. or more and 820 ° C. or less.

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 when the crystallization heat treatment is not performed on the quenched alloy, the rapidly solidified alloy itself can exhibit sufficient magnet properties. Therefore, the crystallization heat treatment is not an essential step of the present invention, but it is preferable to perform this heat treatment for improving the magnet properties. In addition, it is possible to sufficiently improve the magnet properties even with a heat treatment at a lower temperature than in the related art.

The heat treatment atmosphere is used to prevent oxidation of the alloy.
Ar gas or N under 50 kPa _TwoInert such as gas
Gas is preferred. Heat treatment in a vacuum of 0.1 kPa or less
You may go.

Before the heat treatment, the quenched alloy contains Nd ₂ Fe ₁₄
In addition to the B-type compound phase and the amorphous phase, Fe ₃ B
Phase, a metastable phase such as Fe ₂₃ B ₆ , R ₂ Fe ₁₄ B phase, and R ₂ Fe ₂₃ B ₃ phase. In that case, the heat treatment causes the R ₂ Fe ₂₃ B ₃ phase to disappear, and an iron-based boride (eg, Fe ₂₃ B ₆ ) exhibiting a saturation magnetization equal to or higher than the saturation magnetization of the R ₂ Fe ₁₄ B phase. And α-Fe can be crystal-grown.

In the case of the present embodiment, even if a soft magnetic phase such as α-Fe finally exists, the soft magnetic phase and the hard magnetic phase are magnetically coupled by exchange interaction. The magnetic properties are exhibited.

The average crystal grain size of the Nd ₂ Fe ₁₄ B type compound phase after the heat treatment needs to be 300 nm or less which is a uniaxial crystal grain size, preferably 20 nm or more and 150 nm or less, and more preferably 20 nm or more and 100 nm or less. Is more preferable. In contrast, the boride phase and α-Fe
If the average crystal grain size of the phase exceeds 50 nm, the exchange interaction acting between the constituent phases is weakened, and the squareness of the demagnetization curve is deteriorated, so that (BH) _max is reduced. If the average crystal grain size is less than 1 nm, a high coercive force cannot be obtained. From the above, the average crystal grain size of the soft magnetic phase such as the boride phase and the α-Fe phase is preferably from 1 nm to 50 nm, more preferably from 5 nm to 30 nm.

The quenched alloy ribbon may be roughly cut or pulverized before the heat treatment.

After the heat treatment, the obtained magnet is finely pulverized to produce magnet powder (magnetic powder), and various bonded magnets can be manufactured from the magnetic powder by a known process. When producing a bonded magnet, the iron-based rare earth alloy magnetic powder is mixed with an epoxy resin or a nylon resin and formed into a desired shape. At this time, other types of magnetic powder, for example, Sm—Fe—N-based magnetic powder or hard ferrite magnetic powder may be mixed with the nanocomposite magnetic powder.

Various rotating machines such as motors and actuators can be manufactured using the above-described bonded magnets.

When the produced magnetic powder is used for an injection-molded bonded magnet, it is preferable to grind the powder so that the average particle diameter is 200 μm or less, and more preferably the average particle diameter of the powder is 30 μm or more and 150 μm or less. When used for compression-molded bonded magnets, it is preferable to grind the particles so that the particle size is 300 μm or less, and more preferably the average particle size of the powder is 30 μm or more and 250 μm or less. A more preferred range is from 50 μm to 200 μm.

Examples and Comparative Examples are shown in Table 1 below.
The composition formula containing the rare earth impurity R is (Nd_1-m
R_m) ₉Fe₇₆B₁₂Ti_Three(At%)
Gold samples (No. 1 to No. 16) were prepared. Each sample
To produce B, Fe, T having a purity of 99.5% or more.
i, Nd, R (Y, La, Ce, Pr, Tb, or D
y) is weighed (total 30 grams)
And then put into a quartz crucible. In Table 1, R
In the column indicated by, the type of the rare earth impurity R and its content
Rate m is described, for example, “Y0.08”
All rare earth elements including Nd (Nd_1-mR_m), Y is 8
at% is contained.

Sample No. Sample No. 1 shows the case where the total amount of Nd does not include rare earth impurities. Sample Nos. 2 to 4 and 8 to 10 show the case where any of Y, La and Ce is contained as a rare earth impurity. 5-7
And 11 to 16 are Pr, Tb, as rare earth impurities.
The case where any of Dy is included is shown.

[0066]

[Table 1]

Since the quartz crucible used for preparing the molten metal has an orifice having a diameter of 0.8 mm at the bottom, the above-mentioned raw material is melted in the quartz crucible and then dropped as an alloy melt from the orifice. Will be. Dissolution of raw materials
This was performed using a high-frequency heating method in an argon atmosphere at a pressure of 40 kPa. In this embodiment, the melt temperature is set to 150
It was set to 0 ° C.

By pressurizing the surface of the molten alloy with Ar gas at 26.7 kPa, 0.7 m below the orifice was obtained.
The molten metal was allowed to flow down to the outer peripheral surface of the copper roll at the position of m. The roll rotates while its inside is cooled such that the temperature of the outer peripheral surface is maintained at about room temperature. For this reason, the molten alloy flowing down from the orifice is blown in the peripheral speed direction while being in contact with the roll peripheral surface and depriving of heat. Since the molten alloy is continuously dropped on the roll peripheral surface through the orifice, the alloy solidified by the rapid cooling is a ribbon (width: 2 to 3 mm, thickness: 50) extended in a ribbon shape.
１２０120 μm).

The structure of the liquid crystal quenched alloy thus obtained was examined using characteristic X-rays of CuKα.
1 to No. All 16 samples had a halo pattern, indicating that an amorphous-like rapidly cooled alloy structure was formed.

Next, No. 1 to No. The 16 quenched alloys were heat-treated in Ar gas. Specifically, each quenched alloy was held at the heat treatment temperature shown in the second column from the left in Table 1 for 6 minutes, and then cooled to room temperature. Thereafter, the magnetic properties of each sample were measured using a vibrating magnetometer. The three columns on the right side of Table 1 above show the coercive force H _CJ (kA / m), the maximum energy product (BH) _max (kJ / m ³ ), and the residual magnetic flux density Br.
(T) is shown.

As can be seen from Table 1, as an impurity, R1
When (Y, La, Ce) is contained, its amount is 8 at% of the entire rare earth element (No. 2 to 4), when it is 15 at% or less, the coercive force H _CJ is high, and when the total amount of the rare earth element is Nd ( It can be seen that the value of the maximum energy product (BH) _max did not decrease by 20% or more compared to No. 1). On the other hand, when the amount of R1 is 17 at% (No. 8 to 10) and exceeds 15 at%, the maximum energy product (BH)
The value of _max has dropped significantly.

Further, R2 (Pr, Tb, D
y), the content is 8 at% of the total rare earth element
(No. 5 to 7) or 17 at% (No. 11 to 1)
3) When it is 25 at% or less, the coercive force H _CJ is high,
It can be seen that the value of the maximum energy product (BH) _max is not reduced by 20% or more as compared with the case where the total amount of rare earth is Nd (No. 1). On the other hand, the amount of R2 is 27 at%.
(No. 14 to 16) and exceeds 25 at%,
The value of the maximum energy product (BH) _max is greatly reduced.

It should be noted that no. 1 to No. The metal structures of the 16 samples after the heat treatment were also examined by characteristic X-rays of CuKα. As a result, R ₂ Fe ₁₄ B
Although Fe-B phase phase and Fe ₂₃ B ₆ and Fe ₃ B is confirmed, No. Nos. 8 to 10 and Nos. Regarding 14 to 16, remarkable α-Fe diffraction peaks were also confirmed. That is, when the rare earth impurities R1 and R2 are mixed in more than a predetermined amount, it is considered that the effect of Ti, which suppresses the coarsening of α-Fe, is greatly reduced.

[0074]

According to the present invention, when manufacturing an Nd—Fe—B based magnet alloy, the allowable amounts of Y, Ce and La mixed as rare earth impurities are specified, so that expensive high purity Nd Without using, it is possible to produce a permanent magnet having high magnetic properties while using inexpensive low-purity Nd containing Y, Ce, and La.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view showing an example of an entire configuration of an apparatus used for a method of manufacturing a quenched alloy for an iron-based rare earth alloy magnet according to the present invention, and FIG. FIG.

[Explanation of symbols]

 1b, 2b, 8b, and 9b Atmosphere gas supply port 1a, 2a, 8a, and 9a Gas exhaust port 1 Melting chamber 2 Quenching chamber 3 Melting furnace 4 Hot water storage tank 5 Hot water nozzle 6 Roth 7 Rotary cooling roll 21 Melt 22 Alloy ribbon

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4E004 DB02 TA03 TB02 TB04 5E040 AA04 AA19 CA01 HB11 NN01

Claims (8)

[Claims] The composition formula is (Fe _1-k T _k ) _100-xyz Q
_{x (Nd 1-m R1 m} ) y M z ( where, T is Co, one or two elements selected from the group consisting of Ni, Q is one selected from the group consisting of B or C Or two elements, R1 is one or more elements selected from the group consisting of Y, Ce, and La, and M is Al, Si, Ti, V, C
r, Mn, Cu, Zn, Ga, Zr, Nb, Mo, A
g, Hf, Ta, W, Pt, Au, Pb), x, y, z,
An iron-based rare earth permanent magnet alloy in which k and m each satisfy the following formula: 10 <x ≦ 25 atomic% 2 ≦ y ≦ 9.5 atomic% 0 ≦ z ≦ 10 atomic% 0 ≦ k ≦ 0.5 0 <m ≦ 0.15 2. The iron-based rare earth permanent magnet alloy according to claim 1, wherein m satisfies 0.01 ≦ m ≦ 0.15. 3. The iron-based rare earth permanent magnet alloy according to claim 1, wherein said M always contains Ti. 4. The iron-based rare earth permanent magnet alloy according to claim 3, wherein the composition ratio of Ti is 0.5 atomic% or more and 7.0 atomic% or less. 5. The method further includes a rare earth element R2 different from the rare earth element R1 (where R2 is one or more of Pr, Dy, and Tb), and the composition formula is (Fe _{1 -k
T k) 100-xyz Q x} ( represented by _{Nd 1-mn R1 m R2 n} ) y M z, iron-based rare earth-based permanent magnet alloy of claim 1, n satisfies the following values. 0 <n ≦ 0.25 6. The iron-based rare earth permanent magnet alloy according to claim 5, wherein m and n satisfy the following formulas. 0 <m + n ≦ 0.25 7. The composition formula is (Fe _1-k T _k ) _100-xyz Q
_{x (Nd 1-m R1 m} ) y M z ( where, T is Co, one or two elements selected from the group consisting of Ni, Q is one selected from the group consisting of B or C Or two elements, R1 is one or more elements selected from the group consisting of Y, Ce, and La, and M is Al, Si, Ti, V, C
r, Mn, Cu, Zn, Ga, Zr, Nb, Mo, A
g, Hf, Ta, W, Pt, Au, Pb), x, y, z,
Iron-based rare earth element in which k and m each satisfy 10 <x ≦ 25 atomic% 2 ≦ y ≦ 9.5 atomic% 0 ≦ z ≦ 10 atomic% 0 ≦ k ≦ 0.5 0 <m ≦ 0.15 Providing a melt of the raw material alloy; supplying the melt of the alloy onto a guide means to form a lateral flow of the melt of the alloy on the guide means, whereby the contact area of the melt with a cooling roll is formed. And quenching the molten alloy by the cooling rolls to obtain Nd ₂
A method for producing an iron-based rare earth permanent magnet alloy, comprising: a cooling step of producing a quenched alloy containing an Fe ₁₄ B-type compound phase. 8. A rare earth magnet produced by subjecting an iron-based rare earth permanent magnet alloy produced by the production method according to claim 7 to crystallization heat treatment.