JP2597843B2 - Rare earth magnet and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention mainly comprises a rare earth metal (R), a transition metal (T), and boron (B) typified by Nd, Fe, B-based permanent magnets. The present invention relates to a rare earth magnet material comprising an R ₂ T ₁₄ B-based intermetallic compound and a method for producing the same, and more particularly to a rare earth magnet material having improved corrosion resistance and plastic workability and a method for producing the same.

[Conventional technology]

The mainstream of permanent magnets currently used are magnetoplumbite ferrite magnets, alnico magnets, Sm-C
oSystem magnet. These magnet materials have drawbacks such as being very brittle against mechanical stress, easily cracking, and chipping. Therefore, these magnets cannot be mechanically processed such as stretching into a thin wire or stretching thinly. Therefore, a predetermined shape is obtained by processing such as cutting, grinding and polishing of the magnet.

Conversely, some of the limited magnet materials have excellent mechanical spreadability. For example, high Br, Fe-Cr is low _I H _C
-Co-based or Cuni, which is easy to process but has low magnet properties
fe and Cunico, MnAlC-based magnets with moderate magnet properties but high processing temperatures, and PtCo-based magnets that exhibit high magnet properties but are expensive due to the use of large amounts of precious metals.

However, R / T / B magnets having excellent magnet properties are completely different from the above-mentioned magnet materials, and have poor mechanical spreadability.

On the other hand, regarding the method of manufacturing RTB rare earth magnets,
It is roughly classified into two methods, a liquid quenching type and a sintering type.
The liquid quenching type manufacturing method is based on the method of ultra-quenching a molten alloy, in which fine crystal grains (usually 0.05 to
Liquid quenched micro-crystallized ribbons obtained by adjusting the cooling rate to include about 0.1 μm), and then combining them with a polymer resin, or press molding uniaxially at high temperatures Then, a liquid quenching type magnet is generated.

In general, alloy powder used for liquid quenching type magnets is sprayed from an alloy melted by high frequency or the like on an Fe or Cu roll rotating at high speed in an inert atmosphere such as an Ar atmosphere.
It is obtained by pulverizing a quenched ribbon having a thickness of about several tens of μm. At this time, the cooling rate of the melted alloy can be controlled by changing the rotation speed of this roll.
A quenched ribbon containing fine crystal grains of about 0.1 μm is 20 m / se
It can be obtained in a very limited range where the roll peripheral speed is about c. That is, the quenched ribbon thus obtained is roughly pulverized according to the purpose, and then magnetized.

On the other hand, in a method of manufacturing a sintered magnet, an ingot of a crystalline magnet alloy obtained by melting is finely pulverized, molded in a magnetic field, and then sintered to obtain a sintered magnet. The manufacturing process generally proceeds in the order of melting, grinding, orientation in a magnetic field, compression molding, sintering, and aging of the raw material alloy. Melting is usually performed in a vacuum or inert atmosphere such as an arc or high frequency, and an alloy raw material ingot is first obtained. The pulverization is divided into coarse pulverization and fine pulverization, and the coarse pulverization is performed by a jaw crusher, a disc mill, a roll mill, or the like. The magnetic field orientation and compression molding are usually performed simultaneously in a magnetic field using a mold. Sintering is performed in an inert atmosphere at a temperature in the range of 1000 to 1150 ° C. Aging takes place at temperatures around 600 ° C.
Hold for about an hour.

[Problems to be solved by the invention]

However, of the above two methods for producing R, T, and B rare earth magnets, the former liquid quenching type manufacturing method is more difficult to orient in a magnetic field than the latter sintered type manufacturing method. Therefore, there is a disadvantage that a rare-earth magnet having high anisotropy cannot be easily obtained.

Moreover, when the R composition value is increased in order to enhance the spreadability of the rare-earth magnet itself, there is a disadvantage that the magnet properties are degraded.

In addition, rare earth magnets have a disadvantage that they are very easily oxidized as compared with other types of magnets because they necessarily contain a large amount of chemically active rare earth metals.

In view of the above drawbacks, an object of the present invention is to provide a rare earth magnet having high anisotropy, a rare earth magnet having excellent spreadability and a rare earth magnet having excellent oxidation resistance, or a rare earth magnet having a combination of these excellent properties. Is to provide a magnet.

[Means for Solving the Problems] According to the present invention, the magnet alloy surface is coated with a metal having excellent spreadability and corrosion resistance, and the powder compact or sintered compact is thinned or rolled. A rare earth magnet comprising Nd, Fe, B as a main component and having a crystal grain size of 10
R ₂ T ₁₄ B-based magnet material that is a liquid quenched crystallized alloy powder of [μm] or less or an amorphous liquid quenched alloy powder (where R is Y
A rare earth metal composed of at least one of Ce, Pr, Nd, Gd, Tb, Dy, and Ho, and T represents a transition metal composed of at least one of Al, Cr, Mn, Fe, Co, and Ni; R is 37
9090 [wt%]) is obtained.

On the other hand, according to the present invention, an R ₂ T ₁₄ B-based magnet material containing Nd, Fe, B as a main component (where R is Ce, Pr, Nd, Gd, T
b, Dy, and Ho are rare earth metals, and T represents a transition metal consisting of at least one of Al, Cr, Mn, Fe, Co, and Ni).
An R ₂ T ₁₄ B-based magnet material used in the coating step, comprising a coating step of coating with a metal having excellent spreadability and corrosion resistance, and a thinning step of thinning the rare-earth magnet coated with the metal. Is a rare-earth magnet that is a liquid quenched crystallized alloy powder or an amorphous liquid quenched alloy powder with a composition value of R in the range of 37 to 90 [wt%] and a crystal grain size of 10 [μm] or less. Is obtained.

On the other hand, according to the present invention, an R ₂ T ₁₄ B-based magnet material containing Nd, Fe, B as a main component (where R is Ce, Pr, Nd, Gd, T
b, Dy, and Ho are rare earth metals, and T represents a transition metal consisting of at least one of Al, Cr, Mn, Fe, Co, and Ni).
R ₂ T used in the sandwiching step includes a sandwiching step of sandwiching between metal bodies having excellent spreadability and corrosion resistance, and a rolling step of rolling the rare earth magnet after being sandwiched between the metal bodies.
₁₄ B-based magnet material is a liquid quenched crystallized alloy powder with an R composition value in the range of 37 to 90 [wt%] and a crystal grain size of 10 [μm] or less, or an amorphous liquid quenched alloy. A method for producing a rare earth magnet as a powder is obtained.

In other words, R, T, and B, which have been considered difficult to extensibility,
In the rare earth intermetallic compound magnets, by limiting the R composition value (37-90 wt%) of the composition of the R, T, and B compound, plastic working, especially workability by sheathing and oxidation resistance, etc. Have been found as a result of various experiments.

In the present invention, the reason that the composition value of R is in the range of 37 to 90 wt% is that when the composition value of R is 37 wt% or less, the ductility of the magnet is not remarkable, while when R is 90 wt% or more, (BH) _max is 1M ・ G ・ Oe
This is because the magnetic properties are clearly lower than those of Cunife and Cunico magnet materials, which are easy to plastically process.

Liquid quenched alloy powder, amorphous alloy powder or
The reason for using the liquid quenched crystallized alloy powder is as follows.

When a magnet alloy ingot is used as a raw material, rough pulverization and fine pulverization can be sufficiently performed by mechanical pulverization performed by ordinary powder metallurgy up to an ingot having a composition of about 50% by weight of R.

However, ingots with an R of about 50 wt% or more have an increased toughness, so that pulverization becomes more difficult as the R value increases. Therefore, in a composition having an R value exceeding 50% by weight, pulverization can be easily performed by using a liquid quenched alloy ribbon as a raw material. The effect of obtaining a magnet alloy raw material by this liquid quenching method becomes more useful when R is 50 wt% or more, and it can be applied even if the composition is less than this.

Although the reason is not clear, the sample obtained by molding and sintering the liquid quenched alloy powder in a magnetic field shows significantly higher anisotropy than the sample obtained by molding and sintering the alloy ingot powder in a magnetic field. ing. Therefore, when plasticizing these sintered bodies, in the composition region where it is difficult to grind the raw material ingot,
Using a liquid quenched alloy as a raw material is more advantageous in terms of magnet properties.

As for the magnet properties, higher values can be obtained by using the liquid quenched crystallized alloy ribbon than the liquid quenched amorphous alloy ribbon. Although the crystal grain size contained in the liquid quenched crystallized alloy ribbon is about 20 μm or less, the crushability is superior to that of an ingot, but it is preferably about 10 μm or less.

Next, the reason why the surface of the magnet is covered with a metal having excellent spreadability and corrosion resistance and subjected to plastic working is as follows. Since the present magnet contains a large amount of a chemically active rare earth metal, it is extremely easily oxidized as compared with other types of magnets. Further, when large plastic deformation is caused by uniaxial pressing or the like, a crack is easily generated at the end of the workpiece. Therefore, by coating this magnet material with a metal having good spreadability and oxidation resistance or inserting it into it, and then performing plastic working, defects such as cracks do not occur at the ends and oxidation resistance An improved magnet is obtained. At this time, the growth of the magnet particles is controlled in the direction perpendicular to the stress direction at the time of processing, so that anisotropy can be obtained.

In this embodiment described later, the processing temperature is set to 400 ° C. based on the upper limit temperature at which repetitive use is possible when ordinary hardened steel is used as a stamping die.
Therefore, if high speed steel, ceramics, etc. are used,
Plastic working at higher temperatures is possible. In addition, plastic deformation tends to become easier in this magnet alloy when the temperature exceeds about 400 ° C.

〔Example〕

The rare earth magnet of the present invention and the method of manufacturing the same will be described in detail below with reference to examples.

First, the physical properties of the rare earth magnet of the present invention will be briefly described. This rare earth magnet is a rare earth magnet in which the surface of a magnet alloy is coated with a metal having excellent spreadability and corrosion resistance, and a powder compact or sintered compact is thinned or rolled. R ₂ T ₁₄ B-based magnet material containing B as a main component and having a crystal grain size of 10 [μm] or less, or a liquid quenched crystallized alloy powder or an amorphous liquid quenched alloy powder (where R is Y is a rare earth metal composed of at least one of Ce, Pr, Nd, Gd, Tb, Dy, and Ho, and T represents a transition metal composed of at least one of Al, Cr, Mn, Fe, Co, and Ni. , R is in the range of 37 to 90 [wt%]).

When producing such a rare earth metal, an R ₂ T ₁₄ B-based magnet material containing Nd, Fe, and B as a main component (where R includes Y
Is a rare earth metal composed of at least one of Ce, Pr, Nd, Gd, Tb, Dy, and Ho, and T represents a transition metal composed of at least one of Al, Cr, Mn, Fe, Co, and Ni) It is sufficient to include a coating step of coating the rare earth magnet to be coated with a metal having excellent spreadability and corrosion resistance, and a thinning step of thinning the rare earth magnet after being coated with the metal. ,
In the coating process, the R ₂ T ₁₄ B-based magnet material is changed to a composition value of R of 37 to 90.
It may be liquid quenched crystallized alloy powder or amorphous liquid quenched alloy powder having a range of [wt%] and a crystal grain size of 10 [μm] or less.

Such a rare earth metal is a R ₂ T ₁₄ B-based magnet material containing Nd, Fe, B as a main component (where R is Ce, Pr, N containing Y).
a rare earth metal formed by at least one of d, Gd, Tb, Dy, and Ho, and T representing a transition metal consisting of at least one of Al, Cr, Mn, Fe, Co, and Ni) Can also be manufactured by including a sandwiching step of sandwiching the rare earth magnet between metals having excellent spreadability and corrosion resistance, and a rolling step of rolling the rare earth magnet sandwiched between the metal bodies. Also in this case, in the sandwiching step, the R ₂ T ₁₄ B-based magnet material is mixed with a liquid quenched crystallized alloy powder having a composition value of R of 37 to 90 [wt%] and a crystal grain size of 10 [μm] or less. Or an amorphous liquid quenched alloy powder.

Therefore, the method of manufacturing the rare earth magnet and the magnet characteristics will be described in detail below with reference to some specific examples and reference examples.

-Reference Example 1-In Reference Example 1, the extensibility when the R value was less than 50 wt% was compared.

Using 97% by weight of Nd (the remainder is other rare earth elements mainly composed of Ce and Pr), ferroboron (about 20% by weight of pure B) and electrolytic iron, Nd is 34, 37, 40, 43% by weight, respectively. B1.0wt%, balance Fe
And melted by high frequency heating in an argon atmosphere to obtain an alloy ingot.

Next, this ingot was roughly pulverized and then pulverized to about 3 μm using a ball mill. This powder was placed in a magnetic field of 2 kOe for 1 to
It was molded in a magnetic field to a shape of 15 mm in diameter and 10 mm in height at n / cm ² . The compact was held at 1050 ° C. for 1 hour in a vacuum and then for 1 hour in Ar and sintered.

Next, the sintered body was pressed uniaxially at 400 ° C. at a pressure of 3 ton / cm ² . Then, it was kept at 650 ° C. for 1 hour in an Ar atmosphere to age.

Table 1 shows the magnet properties of this sample and the elongation in the radial direction by applying a pressure of 8 ton / cm ² at 400 ° C.

As a result, when Nd is 37wt% or more, plastic deformation of the magnet is clearly observed, indicating that the magnet is excellent in ductility.

-Reference Example 2-In Reference Example 2, the magnet characteristics when the R value was 50% or more were compared. The starting material for the magnet material was an amorphous alloy powder.

In the same manner as in Reference Example 1, Nd was 50, 60, 70, 80, 90 wt%,
An alloy ingot was obtained so that B was 0.8 wt% and the balance was Fe.

Next, using this ingot, redissolve it by high-frequency heating in an Ar atmosphere, spray it onto a Cu roll with a peripheral speed of about 50 m / sec, and use the single roll method to obtain a width of about 2 mm and a thickness of about 30 μm.
Was obtained.

After the amorphous alloy ribbon was roughly pulverized, a molding powder having an average particle diameter of 3 μm was obtained by a ball mill. This powder was subjected to magnetic field molding in the same manner as in Reference Example 1 and Nd was 50 wt% and 60 wt%.
Compacts were sintered at 900 ° C, and compacts with Nd of 70 wt%, 80 wt% and 90 wt% were sintered at 700 ° C.

These sintered compacts were roll-rolled at 400 ° C to reduce the thickness by 1/3.
Reduced to.

Next, the obtained rolled body was aged at 600 ° C. for 2 hours in an Ar atmosphere. Table 2 shows the magnet properties of this sample.

As a result, even with a composition of Nd90wt%, (BH) _max is 1M · G ·
It shows magnet properties exceeding Oe.

-Example 1-Example 1 is a case where a rod-shaped rare earth magnet produced from an amorphous alloy powder having an R value of 60 wt% is inserted into a Cu pipe as a coating process, and a thinning process is performed as a thinning process. The corrosion resistance was compared.

Cerium dymium consisting of 5 wt% Ce, 15 wt% Pr, balance Nd (other residual rare earth elements were included as Nd) and Dy, ferroboron and electrolytic iron having a purity of 95 wt% or more were used. In the same manner as described above, an ingot was obtained in which R was 60 wt%, B was 0.9 wt%, and the balance was Fe so that Dy in the rare earth was 5 at%.

Next, using this ingot, a liquid quenched amorphous ribbon was obtained in the same manner as in Reference Example 2, and a molding powder was produced. Next, using this powder in a 10 kOe magnetic field, 0.5 to
At a pressure of n / cm ² , a rod-shaped compact having a diameter of 10 mm and a length of about 100 mm was obtained.

This compact was sintered at 850 ° C. in the same manner as in Reference Example 1. Next, the sintered body was processed so as to be inscribed in a Cu pipe with a length of 1 mm and an inner diameter of 8 mm.
The wire was thinned using a swaging die at ℃ and thinned to a diameter of 2 mm.

Next, the thin wire was kept in an Ar atmosphere at 650 ° C. for 0.5 hour to age.

Its magnetic _{properties, Br6.8kG, I H C 15.0kOe,} (BH) max 11.0M
・ It was G ・ Oe. No rust was observed on the side of this magnet coated with Cu for 100 hours at 70 ° C in 90% humidity, but significant rust was generated in the uncoated part in about 1 hour. .

-Example 2-Example 2 is a case where an amorphous alloy powder having an R value of 65 wt% is press-formed in a magnetic field-free state, and then the powder compact is inserted into an Al ring as a coating step and pressed. The magnet characteristics in were compared.

Nd was 65 wt%, B was 0.8 wt%, and the balance was the same as in Reference Example 2.
An amorphous alloy ribbon to be Fe was obtained. This amorphous alloy ribbon was pulverized to an average particle size of about 50 μm, and then heat-treated at 650 ° C. for 1 hour in an Ar atmosphere.

Next, this powder was applied under a magnetic field of ² ton / cm ² under a magnetic field of 15 m in diameter.
It was press molded to a height of 10 mm.

Next, after inserting this pressed compact into an Al ring having an inner diameter of 15 mm and an outer diameter of 17 mm, a thickness of 5 mm was applied at 400 ° C under a pressure of 5 ton / cm ² .
Pressure molding was performed to a diameter of 19 mm.

Magnetic properties of this sample _{Br4.5kG, I H C 12kOe, (} BH) max 4.
It was 5M · G · Oe. In Example 2 and Examples 5 and 6, which will be described later, since the powder compact is sandwiched between a cylindrical tube and upper and lower metal plates, the shape of the compact during processing can be prevented from being collapsed. The bonding step can be omitted.

Example 3 In Example 3, a rare earth magnet produced by forming an amorphous alloy powder having an R value of 60 wt% in a magnetic field was sandwiched between Al plates as a sandwiching step.
The magnet properties and the corrosion resistance when the rolling process was performed as the rolling process were compared.

Composition Nd60wt%, B0.8wt%, balance Fe made in Reference Example 2
After crushing the amorphous alloy ribbon of
Heat treatment was performed at 800 ° C. for 1 hour in an atmosphere.

This powder was molded in a magnetic field of 30 kOe under a pressure of ² ton / cm ^{2 to} a width of 50 mm, a length of 100 mm, and a thickness of 10 mm (in the direction of the applied magnetic field).

Next, after sandwiching this compact vertically with a 1 mm thick Al plate,
Rolling was performed at 0 ° C. to a thickness of 3 mm.

Next, the rolled compact was kept at 550 ° C. for 2 hours and aged.

Magnetic properties of this magnet _{Br6.2kG, I H C 15.0kOe, (} BH) max
8.5M · G · Oe.

In addition, the surface of this magnet coated with Al
No rust was observed even after holding at 100 ° C. for 100 hours, but significant rust occurred in the uncoated part in about 1 hour.

-Reference Example 3-Reference Example 3 compares the ductility and magnet properties of rare earth magnets produced using amorphous alloy powder and microcrystallized alloy powder, which are liquid quenched alloys with an R value of 40 wt%, as starting materials. did.

Using Nd with purity of 97wt% (the remainder is other rare earth elements mainly composed of Ce and Pr), ferroboron (B pure content about 20wt%) and electrolytic iron, 40wt% of rare earth element (R) and 1.0wt% of B , Rest F
The alloy was melted by high-frequency heating in an argon atmosphere to obtain an alloy ingot.

Next, after using this ingot to redissolve by high-frequency heating in an Ar atmosphere, the peripheral speed was increased to about 50 m / sec and about 10 m.
sprayed onto a Cu roll changed to / sec, and a single roll method was used to form an amorphous alloy ribbon with a width of about 2mm and a thickness of about 20μm, and a width of about 10m.
A liquid quenched microcrystallized alloy ribbon having a thickness of about 100 μm was obtained.
The microcrystallized quenched alloy ribbon contained fine crystal grains of about 3 μm or less.

Each of these liquid quenched alloy ribbons was roughly pulverized, and then pulverized to an average particle size of about 3 μm using a ball mill. Each of these powders is 15 mm in diameter and 10 m in height at a pressure of 1 ton / cm ^{2 in} a magnetic field of 20 kOe.
m. The obtained compact was kept in vacuum at 1020 ° C. for 1 hour, and then kept in Ar for 1 hour and sintered.

Next, this sintered body was pressed uniaxially at 400 ° C. at a pressure of 8 ton / cm ² . After that, it was kept at 600 ° C. for 1 hour in an Ar atmosphere to age. The magnetic properties of this sample and 400 ° C, 8ton / cm ²
Table 3 shows the elongation percentage in the radial direction by pressurizing.

As a result, although the extensibility is the same, the use of the finely crystallized alloy ribbon shows significantly higher magnet properties.

Reference Example 4 In Reference Example 4, the extensibility and the magnet properties of the rare earth magnets produced by using an ingot having an R value of 70 wt% and a microcrystalline quenched alloy ribbon as starting materials were compared.

As in Reference Example 3, R was 70 wt%, B was 1 wt%, and the balance was Fe.
And a liquid quenched microcrystallized alloy ribbon about 5mm wide and about 50μm thick. The alloy ribbon contained fine crystal grains of about 1 μm or less.

The quenched ribbon and ingot were roughly pulverized and then finely pulverized using a ball mill. As a result, compared to quenched ribbons,
Since the ingot has remarkably reduced grindability and shows a wide particle size distribution, a large amount of coarse particles are present, and the average particle size is about 2%.
Even when pulverized to a size of μm, the powder for molding had reduced homogeneity. (Because the reaction such as oxidation is very remarkable in this magnet alloy, pulverization with an average particle size of about 2 μm or less is not preferable.) Therefore, when the pulverization was performed under constant pulverization conditions, the quenched ribbon powder was reduced 3 μm and ingot powder was about 30 μm. This powder was compacted in a magnetic field in the same manner as in Reference Example 3, sintered at 700 ° C., deformed under pressure, and aged. Table 4 shows the magnet properties of this sample and the elongation percentage in the radial direction due to deformation under pressure at 400 ° C.

As a result, the use of the microcrystallized quenched ribbon shows clearly higher ductility and magnet properties.

-Reference Example 5-In Reference Example 5, the extensibility and magnet properties of a rare earth magnet produced using a liquid quenched crystallized alloy powder having an R value of 37 wt% or more as a starting material were compared.

In the same manner as in Reference Example 3, R was 34, 37, 40 wt%, B 1.0 wt%,
After obtaining three kinds of ingots to be the remaining Fe, a liquid quenched crystallized alloy ribbon having a width of about 10 mm and a thickness of about 100 μm was obtained. still,
This rapidly crystallized alloy ribbon contained fine bonded grains of about 3 μm or less.

The quenched crystallized alloy ribbon was used, pulverized, formed in a magnetic field, and sintered in the same manner as in Reference Example 3, and then pressed uniaxially at 400 ° C. at a pressure of 8 ton / cm ² . After that, it was aged at 600 ° C for 5 hours.

Table 5 shows the magnet properties of this sample and the elongation percentage in the radial direction by applying a pressure of 8 ton / cm ² at 400 ° C.

As a result, with R-values 37 wt% or more, high ductility can clearly be recognized, also, is also observed improvement of _I H _C.

-Reference Example 6-Reference Example 6 compared the magnet properties of rare earth magnets using a liquid quenched crystallized alloy powder as a starting material when the R value was 50 wt% or more.

As in Reference Example 3, R was 50, 70, 90 wt%, B 1.0 wt%,
After obtaining three kinds of ingots to be the remaining Fe, a liquid quenched crystallized alloy ribbon having a width of about 10 mm and a thickness of about 100 μm was obtained. still,
The quenched alloy ribbon contained fine crystal grains of about 5 mm or less.

Using this quenched ribbon, pulverization and molding in a magnetic field were performed in the same manner as in Example 1, and then a molded body having an R of 50 wt% was heated at 900 ° C.
Were sintered at 700 ° C. at 70 and 90 wt%.

The sintered body was roll-rolled at 400 ° C. to reduce the thickness by half. Next, the rolled body was aged at 600 ° C. for 2 hours in an Ar atmosphere. Table 6 shows the magnet properties of this sample.

As a result, (BH) _max is 1M · G even with a composition with an R value of 90 wt%.
・ Shows magnet properties exceeding Oe.

-Example 4 In Example 4, a rod-shaped rare earth magnet produced from a liquid quenched crystallized alloy powder having an R value of 60 wt% was inserted into a Cu pipe as a coating step, and thinning was performed as a thinning step. The magnet properties and corrosion resistance in the cases were compared.

Cerium dymium consisting of 5 wt% Ce, 15 wt% Pr, balance Nd (other rare earth elements were included as Nd) and 95 wt% pure Dy, ferroboron and electrolytic iron were used. R60wt so that Dy in R becomes 5at%.
%, B0.9wt%, balance ingot after obtaining ingot which is Fe
A liquid quenched crystallized ribbon of 0 mm and a thickness of about 100 μm was obtained. still,
The quenched alloy ribbon contained fine crystal grains of about 5 mm or less.

Next, using this quenched ribbon, pulverization was performed in the same manner as in Reference Example 3, and a rod-shaped compact having a diameter of 10 mm and a length of about 100 mm was obtained in a 10 kOe magnetic field at a pressure of 0.5 ton / cm ^2. Was.

This compact was sintered at 850 ° C. in the same manner as in Reference Example 3. Next, this sintered body was processed so as to be inscribed in a Cu pipe with a thickness of 1 mm and an inner diameter of 8 mm, and then inserted into the Cu pipe.
Using a swaging die at 0 ° C., the wire was thinned to a diameter of 2 mm.

Next, this thin wire was aged at 650 ° C. for 0.5 hour in an Ar atmosphere.

Its magnetic _{properties, Br7.4kG, I H C 15.0kOe,} (BH) max 12.5M
・ It was G ・ Oe. No rust was observed on the side of the magnet coated with Cu at 70 ° C in 90% humidity for 100 hours, but no rust was observed in the uncoated part in about 1 hour. Was.

-Example 5-In Example 5, a liquid quenched crystallized alloy powder having an R value of 65 wt% was press-formed in a magnetic field, and then the powder compact Al was formed as a coating step.
The magnet characteristics in the case where the magnet was inserted into a ring made and pressed were compared.

As in Reference Example 4, R was 65 wt%, B was 0.8 wt%, and the balance was F
A liquid quenched crystallized alloy ribbon having a width of about 10 mm and a thickness of about 100 μm was obtained. After quenching the quenched ribbon to about 50 μm,
Heat treatment was performed at 600 ° C. for 1 hour in an atmosphere.

Next, the liquid quenched crystallized alloy powder was molded in a magnetic field in the same manner as in Reference Example 3. This pressed body is 15 mm in inner diameter,
After being inserted into an Al ring having an outer diameter of 17 mm, it was pressed at 400 ° C. with a pressure of 5 ton / cm ² to a thickness of 5 mm and a diameter of about 19 mm.

Magnetic properties of this _{sample, Br4.7kG, I H C 12.0kOe,} (BH)
_{The maximum was} 5.0M · G · Oe.

-Example 6-In Example 6, a rare earth magnet produced from a liquid quenched crystallized alloy powder having crystal grains of 5 µm or less was used as a sandwiching step by using Al as a sandwiching step.
The magnet properties and corrosion resistance in the case where the sheet was sandwiched and rolled as a rolling process were compared.

Using Nd with a purity of 97 wt% (the remainder is other rare earth elements mainly composed of Ce and Pr), ferroboron, electrolytic iron, electrolytic cobalt and aluminum, the R is 60 wt% in the same manner as in Example 2.
%, B is 1.1 wt%, a width of about 10mm and the balance being the Fe ₈₇ · Co ₁₀ · Al ₃
As a result, a liquid quenched crystallized alloy ribbon having a thickness of about 100 μm was obtained.
The quenched alloy ribbon contained fine crystal grains of about 5 μm or less.

Next, this liquid quenched crystallized alloy ribbon is made to have an average particle size of about 10μ.
After being crushed to 30 mOm, the width is 50 m at a pressure of ² ton / cm ^{2 in} a magnetic field of 30 kOe
m, length 100 mm, thickness 10 mm (direction of applied magnetic field).

Next, after sandwiching this compact vertically with a 1mm thick Al plate,
It was rolled at 400 ° C. to a thickness of 3 mm.

Next, the rolled compact is held at 550 ° C. for 5 hours.
It became stale. Magnetic properties of the magnet, Br6.2kG, _I H _C 14.5kOe,
(BH) _max 8.5 M · G · Oe.

The surface of this magnet coated with Al is 70 ° C in 90% humidity.
No rust was observed after holding for 100 hours at
The uncoated portion was significantly rusted in about one hour.

As shown in the above examples, in the R ₂ T ₁₄ B-based magnet containing Nd, Fe, and B as main components, 1) In the magnet composition, the composition value of R is 37 to 90 wt%.

2) An amorphous alloy powder or a liquid quenched crystallized alloy powder which is a liquid quenched alloy having the above composition is used as a starting material.

3) Cover the surface of the compact or sintered body with a metal having good spreadability and corrosion resistance, and perform plastic working.

As described in the above 1) to 3), it is possible to easily produce a thin wire or thin plate magnet which has been conventionally difficult to produce with a simple production process and which tends to increase the cost. In addition to the fact that it becomes possible, the corrosion resistance is also improved by the action of the coating metal, which is extremely useful in industry.

In the above embodiment, NdFeB system, CePrNdDyFe
・ Only B type was described, but part of Nd was replaced with Y and other rare earth metals such as Gd, Tb, Ho, etc.
And other transition metals such as Cr, Mn, Co, Ni, etc.
The composition of the magnet alloy is Nd / Fe even if part of
・ If B is a part of the main component, and R ₂ T ₁₄ B as represented by Nd ₂ Fe ₁₄ B is a magnet compound, it contributes to the present invention. It can be easily inferred that the effect can be sufficiently expected.

In this embodiment, the plastic working is described only for press, roll rolling, and swaging. However, the present invention is not limited to this, and other plastic working is possible as long as a magnet having a desired shape can be obtained. Obviously, the present invention can also be applied to a processing method (for example, extrusion or the like).

In this example, only Cu and Al were described as metals coated on the magnet surface after processing. However, the present invention is not limited to this. It can be easily inferred that any excellent metal is within the scope of the present invention.

In the plastic working of magnets described above, the magnet
_{Although I} H _C and _B H _C can be seen to decrease, it is usually 500 ° C to 700 ° C.
It can be recovered by heat treatment at about ° C.

〔The invention's effect〕

As described above, according to the present invention, in the R ₂ T ₁₄ B-based magnet, 1) R is 37 to 90 wt% in the magnet composition.

2) Use liquid quenched alloy powder as R ₂ T ₁₄ B magnet material.

3) Cover the surface of the compact or sintered body with a metal having good spreadability and corrosion resistance, and perform plastic working.

As described in the above 1) to 3), it is possible to easily produce a thin wire or thin plate magnet which has been conventionally difficult to manufacture with a simple manufacturing process and which tends to increase the cost. In addition, the corrosion resistance is improved by the action of the coating metal, which is extremely useful in industry.

 ──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-57-141901 (JP, A) JP-A-59-76856 (JP, A) JP-A-60-152652 (JP, A) JP-A 61-141 150201 (JP, A) JP-A-61-129802 (JP, A) JP-A-61-48904 (JP, A) JP-A-60-54406 (JP, A)

Claims (3)

(57) [Claims] 1. A rare earth magnet comprising a magnet alloy surface coated with a metal having excellent spreadability and corrosion resistance, and a powder compact or sintered compact thinned or rolled.
Contains e and B as main components and has a crystal grain size of 10 [μm]
The following liquid quenched crystallized alloy powders or amorphous liquid quenched alloy powders of R ₂ T ₁₄ B-based magnet materials (where R is C containing Y
e is a rare earth metal composed of at least one of Pr, Nd, Gd, Tb, Dy, and Ho; T is a transition metal composed of at least one of Al, Cr, Mn, Fe, Co, and Ni; Composition value is 37-90
[Wt%]). 2. An R ₂ T ₁₄ B-based magnet material containing Nd, Fe, and B as main components (where R is Ce, Pr, Nd, Gd, Tb, Dy, and Ho containing Y).
T is Al, Cr,
A transition metal consisting of at least one of Mn, Fe, Co, and Ni), and a step of coating the rare earth magnet with a metal having excellent spreadability and corrosion resistance. The R ₂ T ₁₄ B-based magnet material used in the coating step has a composition value of R in the range of 37 to 90 [wt%] and a crystal grain size. Is 10
A method for producing a rare earth magnet, wherein the powder is a liquid quenched crystallized alloy powder of [μm] or less or an amorphous liquid quenched alloy powder. 3. An R ₂ T ₁₄ B-based magnet material containing Nd, Fe, and B as main components (where R is Ce, Pr, Nd, Gd, Tb, Dy, and Ho containing Y).
T is Al, Cr,
A transition metal consisting of at least one of Mn, Fe, Co, and Ni) and a step of sandwiching a rare earth magnet between metal bodies having excellent spreadability and corrosion resistance. The R ₂ T ₁₄ B-based magnet material used in the sandwiching step has a composition value of R in the range of 37 to 90 [wt%] and a crystal grain size. Liquid quenched crystallized alloy powder with a diameter of 10 [μm] or less,
Or a method for producing a rare earth magnet, characterized by being an amorphous liquid quenched alloy powder.