JP2746223B2 - Rare earth-Fe-B cast permanent magnet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] [0001] The present invention relates to an excellent magnetic characteristic.
Rare earth element containing Y (hereinafter referred to as R)
The present invention relates to a permanent magnet of an Fe-B alloy casting. [0002] 2. Description of the Related Art R-Fe-B permanent magnets are rare earth permanent magnets.
Attention as magnet with excellent magnetic properties
Have been. The structure of the R-Fe-B-based permanent magnet is as follows.
In general, the main phase R, which is a ferromagnetic phase and has a tetragonal structure,_Two
Fe₁₄B intermetallic compound phase (hereinafter referred to as R_TwoFe₁₄B phase
) And an R-rich phase and a B-rich phase.
In the R-Fe-B-based permanent magnet, the magnetic characteristics are as described above.
It depends greatly on the microstructure of the R-Fe-B permanent magnet.
Utilizes the excellent magnetic properties of R-Fe-B alloys
Development of permanent magnets with such an organizational form
Was. At present, as the R-Fe-B permanent magnet,
Are as follows. (1) Characterized by a sintered body produced by powder metallurgy
Permanent magnet (for example, Japanese Patent Laid-Open No. 59-460008)
Report). [0005] A permanent magnet (hereinafter, referred to as "the sintered body")
First, the sintered magnet) is formed of an R-Fe-B alloy.
Gott or coarse powder is pulverized by various methods and
Fine powder of about
It is a green compact molded inside. Next, the compact is placed in a vacuum.
Or sintering by raising the temperature from room temperature in a non-oxidizing gas atmosphere.
Temperature: Conditions for holding at 900 to 1200 ° C for 30 to 120 minutes
In order to increase the coercive force if necessary
After that, heat treatment at an appropriate temperature and then cooling
It is manufactured. The magnetic properties of the above sintered magnets are isotropic
If sex, BH_max= About 10 MGOe, anisotropic
In the case of BH_max= 30 MGOe or more. The structure of the above sintered magnet is shown in FIG.
In addition, the main phase of the R-Fe-B permanent magnet R_TwoFe₁₄B
Phase 1, B-rich phase 3, and R_TwoFe₁₄B phase 1 or B-
Consists of R-rich phase 2 present at grain boundaries of rich phase 3
You. R in FIG._TwoFe₁₄Phase B increases coercivity
Therefore, the average grain size is controlled to several μm to 20 μm.
You. (2) Ribbon-like quenched powder by ultra-quenching method
Is subjected to a high-temperature compression-plastically processed permanent magnet (for example,
No. 60-100402) Permanent magnets (hereinafter referred to as "characters") made of a material obtained by compressing this quenched powder
Below, it is called a high-temperature compression magnet).
By rapidly solidifying the EB alloy, a ribbon-shaped
Obtain a flake and heat it to a temperature above 700 ° C for several minutes
High temperature compression, plastic working and then cooling.
Manufactured. [0008] The magnetic properties of the high-temperature compression magnet are isotropic.
In case, BH_max= About 13MGOe, difference due to plastic working
BH by anisotropy_max= About 30 MGOe. Up
In the structure of the high-temperature compression magnet, the main phase has an average crystal grain size: several tens
nm to several hundred nm R_TwoFe₁₄B phase, at the grain boundary
Fine structure with R-rich phase and amorphous phase
The main phase R_TwoFe₁₄B phase is single domain particle size: 0.3μm or less
It is controlled by the organization below. [0009] SUMMARY OF THE INVENTION R-Fe-B based alloy
However, in order to become a permanent magnet having a high coercive force, (a)
  R which is the main phase_TwoFe₁₄The average crystal grain size of phase B is 50 μm
Or less, preferably 0.3 μm or less that can be single domain particles
(B) in the crystal grains of the main phase,
No nucleation impurities or strains when generating magnetic domains, (c)
R which is the main phase_TwoFe₁₄The average crystal grain size of phase B is from several μm
If 50 μm, R_TwoFe₁₄R-
rich phase exists and the above R_TwoFe₁₄The phase B crystal grains are
(D) individual magnetic powder
R_TwoFe₁₄Easy magnetization of crystal magnetic anisotropy in B phase
Have a uniform axis and have magnetic anisotropy.
In particular, R of the main phase of the above (a)_TwoFe₁₄Average crystal of phase B
It is thought that the particle size greatly affects the coercive force.
You. Conventionally, R-Fe-B alloys are simply melted
Of the cast body that has been cast or that has been further homogenized
In the structure, the main phase R_TwoFe₁₄Phase B
Cannot be controlled to several tens of μm or less.
Did not have excellent magnetic properties. this
Therefore, a sintered magnet was used as in the above-mentioned conventional technology (1).
And a high-temperature compression magnet as in the prior art (2).
Thus, the structure of the R-Fe-B alloy is controlled.
Was. [0011] The sintered magnet of the prior art (1) has a main phase.
R that is_TwoFe₁₄The average crystal grain size of the B phase is several μm to 20 μm.
m, the main phase in the sintering process
In consideration of the grain growth of sintering, the fine powder for sintering is usually 3 to
Must be ground to 4 μm. But for permanent magnets
When the R-Fe-B alloy is made into a fine powder of 3 to 4 μm,
Since it is always active, impurities such as oxides are generated in the sintered body.
And the magnetic properties of the sintered magnet vary.
Was. Further, as a permanent magnet, the main phase R _TwoFe₁₄
0.3 μm or less, at which the B phase can be single domain particles, is preferred.
However, in the above sintering method, the oxidation during the fine pulverization is severe,
Can not be. The sintered magnet has a thickness of 3 mm.
In the following thin shapes, as the thickness decreases, the magnetic characteristics
There is also a drawback that the properties are greatly reduced. Such a lack
To supplement the points, add additional elements to the above alloy or sinter
Measures such as improving the process and coating the sintered magnet were taken.
In order to bring out the high magnetic properties of the above sintered magnets,
Rough steps and processing had to be performed. The high-temperature compression magnet of the prior art (2) is as follows:
High-temperature compression and plastic working of quenched powder make it a permanent magnet.
Therefore, applications are limited in terms of the degree of freedom of magnet shape and yield.
Was being controlled. Also, by high-temperature compression and plastic working,
R which is the main phase of the structure_TwoFe₁₄Phase B causes grain growth
In order to reduce the coercive force, the high-temperature compression step
It must be done in a very short time of a few minutes,
In order to obtain permanent magnets with mechanical characteristics, the manufacturing process is complicated.
I had to do it. That is, the above-mentioned conventional techniques (1) and
The R-Fe-B permanent magnet of (2) is once R-Fe-B permanent magnet.
Powdering Fe-B based magnetic alloy, sintering it to RF
Since the EB-based permanent magnet is manufactured, RF
Handling of EB alloy powder is difficult and its sintering method
Must also pay attention to the various
There was a problem that it had to be complicated. [0014] Means for Solving the Problems Accordingly, the present inventors have
R-Fe which is said to be unable to obtain excellent magnetic properties
-To impart excellent magnetic properties to a cast of a B-based alloy
Can be easily obtained by using R-
The idea that Fe-B based permanent magnets can be manufactured
R-Fe-B based casting with excellent magnetic properties
As a result of conducting research to obtain a structured permanent magnet, R-Fe-B
The structure of the cast body of the base alloy is R_TwoFe₁₄Recrystallization assembly of B phase
Organization (this organization will be described in detail later)
R-Fe-B based cast body with better magnetic properties
He obtained the knowledge that he could obtain a permanent magnet. The present invention has been made based on such findings.
From an R-Fe-B alloy casting.
Permanent magnet Average recrystallized grain size: a tetragonal structure of 0.05 to 50 μm
R_TwoFe₁₄Aggregation of recrystallization of intermetallic phase B
R-Fe-B cast permanent magnet with crystal texture
It has a sign. [0016] BEST MODE FOR CARRYING OUT THE INVENTION An R-Fe-B cast of the present invention
The structure of the permanent magnet will be described with reference to FIGS. FIG. 3 shows an R—Fe—B magnet alloy cast.
It is the schematic of the structure | tissue of the casting obtained. In Figure 3 above
And 1 is R_TwoFe₁₄B phase and 2 are R-rich phases. R-
rich phase 2 is the main phase R_TwoFe₁₄Grain boundary mainly in B phase 1
Exists in the department. The cast body shown in FIG.
Processing under the condition, as shown in FIG._TwoFe
₁₄R in the grain of B phase 1 or in the grain boundary_TwoFe₁₄Phase B reunion
Crystals 1 'are generated and they grow as shown in FIG.
Na r_TwoFe₁₄Structure in which B-phase recrystallized 1 ′ is aggregated (hereinafter, referred to as
The structure in which the recrystallized crystals 1 'are assembled is called a recrystallized texture.
U). The above cast body is processed under appropriate conditions.
The specific method of processing will be described later. FIG. 2 shows the cast body shown in FIG.
Starting to process, R_TwoFe₁₄B-phase recrystallization 1 'begins to occur
FIG. 1 is a schematic view of the structure of the cast body at the time of the casting, and FIG.
The structure of the cast body after the processing of the cast body shown in FIG.
FIG. Here, the R—Fe—B system shown in FIG.
Gold R_TwoFe₁₄From B phase 1 to R as shown in FIG._TwoF
e₁₄Generate B phase recrystallized 1 'and grow it
R as shown in 1_TwoFe₁₄From recrystallization 1 'of phase B
Texture (ie, recrystallized texture)
The R formed in FIG. 1 and FIG._TwoFe₁₄Phase B
1 ′ is the individual R in FIG._TwoFe₁₄B phase 1 area
It is not a crystal arrangement with a completely random crystal orientation within
The organization has a certain direction. On the other hand, the R-rich phase 2 in the structure of the cast body is shown in FIG.
As shown in_TwoFe₁₄In the early stage of B phase recrystallization formation
Also remain, and R_TwoFe₁₄B phase recrystallization 1 'grows
The average recrystallized grain size shown in FIG.
Remains even if recrystallized texture with recrystallized 1 '
And remains in a state surrounding the recrystallized texture. Again
One R-rich phase 2 exists at the grain boundary of recrystallization 1 'of the crystal texture.
Partial precipitation may occur. According to the present invention, the R shown in FIG._TwoFe₁₄B
R- having a recrystallization texture in which phase recrystallization 1 'is assembled
R-Fe-B casting comprising a casting of Fe-B alloy
It is characterized by a permanent magnet. Therefore, the R-Fe-B based casting of the present invention
Structured permanent magnets are castings with a recrystallized texture
On the other hand, the conventional techniques (1) and (2)
B-based permanent magnets have no recrystallized texture,
It is completely different in that it is a substance obtained by compressing the body and quenched powder. High R-Fe-B permanent magnet of the present invention
The reason for showing the coercive force is that the main phase R_TwoFe₁₄Phase B reunion
The crystal grain size is 50 μm or less, preferably single domain particles.
0.05-3 μm which is close to 0.3 μm to obtain
There are no impurities or strains in the grains and in the grain boundaries due to the grains,
The boundary between recrystallized texture and recrystallized texture is R-rich
This is because a phase exists. R above_TwoFe₁₄B phase flat
If the average recrystallized grain size is smaller than 0.05 μm, it is difficult to magnetize.
Impractical, low coercivity above 50 μm
R-Fe-B system with excellent magnetic properties
Not a permanent magnet. The R of the present invention_TwoFe₁₄Recrystallization of phase B
R-Fe-B based casting with recrystallized texture in which
Co, Ni, Cr, Mo,
One or more of W, Ti, Zr, Hf
It may be replaced. The recrystallized texture described above is an R-Fe-B alloy.
The gold casting is vacuum- or inert-gas free of hydrogen
Temperature rise to 700-1000 ° C in atmosphere
And subsequently in a hydrogen gas atmosphere, at a temperature of 7
The temperature is maintained at 00 to 1000 ° C. and hydrogen is absorbed in the casting.
After that, the temperature: 700-1000 ° C. and the hydrogen gas pressure:
1 × 10^-1Torr or less or hydrogen gas partial pressure: 1 × 10^-1To
After performing dehydrogenation treatment in a non-oxidizing atmosphere of rr or less
It can be obtained by performing a heat treatment for cooling. Therefore, a cast of an R—Fe—B alloy
The method of manufacturing a permanent magnet is based on the conventional R-Fe-B casting.
It is completely different from the manufacturing method of permanent magnets,
Compared to the method for manufacturing R-Fe-B permanent magnets manufactured from powder
All the manufacturing steps are very simple. The R-Fe-B cast permanent magnet of the present invention
In the method for producing
Mixed gas atmosphere of gas and other inert gas
You. The hydrogen gas pressure is R_TwoFe₁₄Absorb hydrogen in phase B
Pressure that gives sufficient lattice strain for recrystallization to occur.
Pressure is required, and at least hydrogen gas pressure is 0.1 Torr
Must be at least. With hydrogen gas and other inert gases
At least the partial pressure of hydrogen gas is
Must be at least 0.1 Torr. Further, R_TwoFe₁₄Absorb hydrogen in phase B
Temperature and temperature for dehydrogenation are lower than 700 ° C
When the hydrogen is occluded, the cast body cracks and becomes brittle.
Hydrogen remains during the dehydrogenation treatment, greatly improving magnetic properties.
Decrease. Further, R_TwoFe₁₄Absorb hydrogen in phase B
Temperature is higher than 1000 ° C
In this case, the generation and growth of recrystallization is very fast,
It is difficult to control the thickness to 0 μm or less. In a hydrogen gas atmosphere at a temperature lower than 700 ° C.
When a cast of R-Fe-B magnet alloy is placed in
Since it breaks and becomes brittle, the temperature rises to 700 ° C above
The atmosphere is a vacuum or inert gas without hydrogen
Atmosphere must be. When performing the dehydrogenation treatment, the hydrogen gas pressure becomes 1
× 10^-1When dehydrogenation is completed at a pressure above Torr,
Hydrogen remains in the structure and the magnetic properties deteriorate. [0032] Next, a concrete example based on the embodiment of the present invention will be described.
In addition to the description,
A description will be given as to whether or not an excellent effect is obtained. Embodiment 1 Using Nd as a rare earth element, melting in a high frequency melting furnace,
The atomic composition of the Nd-Fe-B system produced by casting is Nd
_14.8Fe_77.1B_8.1Of Nd-Fe-B based alloy
Body in Ar gas atmosphere, temperature: 1100 ° C, 40 hours
After cooling by performing homogenization treatment under the conditions of holding,
8mm x side: 8mm x height: 10mm cut out into blocks
Was. The cast block is placed in a heat treatment furnace and
× 10^-FiveAfter evacuating to a vacuum of Torr,
Temperature: to 810 ° C, and temperature: 810 ° C for 30 minutes
Hold to make the temperature of the cast block uniform at 810 ° C
Later, a flow rate of hydrogen gas of 1 Nl / min (temperature: 20 ° C.)
To the heat treatment furnace up to 1 atm and pressurize the hydrogen gas inside the furnace.
The hydrogen gas was flowed while maintaining the
Hydrogen is absorbed in the building block, and its temperature is 810 ° C.
Hydrogen gas pressure: 1 atm is maintained for 5 hours and the above casting is performed.
After hydrogen is uniformly absorbed in the body block, the temperature is 8
Evacuate at 10 ° C for 1 hour and set the atmosphere in the heat treatment furnace to 1 ×
10^-FiveDehydrogenation of the above cast block as Torr vacuum
Processing was performed. After that, Ar gas is kept in the furnace until it becomes 1 atm.
And the cast block is quenched and Nd-Fe
A -B cast permanent magnet was obtained. FIG. 4 shows the Nd according to the first embodiment of the present invention.
For obtaining a recrystallized structure of a Fe-B cast permanent magnet
3 shows a heat treatment pattern. The obtained cast permanent magnet is pulverized,
Particle size: powder of 200 mesh or less.
When the line diffraction was performed, the main phase, Nd_TwoFe₁₄B phase and N
A diffraction line of the d-rich phase was clearly observed. Further, the above-mentioned cast permanent magnet is scanned with a scanning electron microscope.
Observation of the tissue using a mirror, EPMA (Electron probe
The composition was analyzed using an analyzer. FIG. 8 shows the casting obtained by this embodiment.
FIG. 9 shows a scanning electron micrograph of the permanent magnet.
Run of the above cast body which has just been subjected to the homogenization treatment in Example 1.
An electron micrograph is shown. EPMA (Electron Probe Micro Analyzer)
As a result of the composition analysis, the scanning electron microscope shown in FIGS.
Both bases in the photo are Nd_TwoFe₁₄B phase and its crystal grains
An Nd-rich phase was present at the boundary. Homogenization of Figure 9 above
Nd of cast body as processed_TwoFe₁₄Phase B is given by
With dendrite-like coarse crystal grains of 0 to several thousand μm
there were. The cast body obtained according to the first embodiment shown in FIG.
The permanent magnet is the main phase Nd_TwoFe₁₄B phase is about 1.5 μm
It can be seen that it has recrystallized grains,
Composition analysis by the lobe microanalyzer)
The crystal grains are Nd_TwoFe₁₄It was confirmed to be phase B. Therefore, from FIG.
The obtained cast permanent magnet is not just a cast structure,
New Nd of about 1.5 μm_TwoFe₁₄Many recrystallized grains of phase B
It is clear that it has a number of recrystallized textures
Was. The recrystallized structure is shown in FIG.
It can also be seen that it can be obtained by performing a heat treatment of the following pattern. The permanent magnet of the cast obtained in Example 1 above
Table 1 shows the measurement results of the magnetic properties of the stone. Comparative Examples 1 and 2 Homogenization treatment was performed in the same manner as in Example 1 above, length: 8 mm
× Horizontal: 8mm × Height: 10mm Cast block for heat treatment furnace
Put in 1 × 10^-FiveAfter evacuating to Torr vacuum, the vacuum
Temperature from room temperature to 810 ° C.
Hold for 0 minutes to make the temperature of the cast block uniform at 810 ° C
After that, Ar gas was supplied at a flow rate of 1 Nl / min (20 ° C.) for 1 hour.
atm to the heat treatment furnace and keep the inside of the furnace at 1 atm.
Then, Ar gas is allowed to flow, and the temperature is 810 ° C.-Ar
After maintaining the state of the gas pressure: 1 atm for 5 hours, the temperature:
Evacuation was performed at 810 ° C. for 1 hour.
× 10^-FiveTorr vacuum was applied. After that, 1 atm
Until the casting block is cooled by flowing Ar gas until
To obtain an Nd-Fe-B cast permanent magnet (Comparative Example).
1). In the heat treatment of the first embodiment, hydrogen
1 × 10 without gas^-FiveExample 1 in vacuum of Torr
By performing the same heat treatment, Nd-Fe-B cast permanent magnet
A stone was obtained (Comparative Example 2). The heat treatment patterns of Comparative Examples 1 and 2 were
This is shown in FIGS. The cast body obtained in Comparative Examples 1 and 2
The structure of the negative magnet is similar to the structure shown in FIG.
Nd_TwoFe₁₄B phase has dendrite-like coarse crystal grains
Was. The cast bodies obtained in Comparative Examples 1 and 2 above
Table 1 also shows the measurement results of the magnetic properties of the permanent magnet. As shown in Table 1, the cast permanent magnet of the present invention
High coercive force of 12.5 KOe, showing excellent magnetic properties
You can see that [0049] [Table 1] Examples 2 to 10 and Comparative Examples 3 to 5 Electron beam melting using Nd and Pr as rare earth elements
Nd-Pr-Fe-B system produced by melting and casting in a furnace
Has the atomic composition of Nd_14.6Pr_0.3Fe_78.4B_{6. 7}Is
A cast of an Nd-Pr-Fe-B-based alloy was vertically set to 8 mm x
It was cut out into a block of width: 8 mm × height: 10 mm. this
Put the cast block into the heat treatment furnace and 2 × 10^-FiveTrue of Torr
After evacuation, the hydrogen absorption shown in Table 2 was performed from room temperature in the vacuum.
Temperature to the storage temperature and at the hydrogen storage temperature in Table 2 above for 30 minutes
After holding and equalizing the temperature of the casting block,
Gas at a flow rate of 0.6 Nl / min (temperature: 20 ° C).
Pressure into the heat treatment furnace until it reaches 500 Torr.
Hydrogen gas pressure while maintaining the inside at 500 Torr
To reduce the flow of hydrogen into the casting block.
The hydrogen storage temperature in Table 2-hydrogen gas pressure: 500 Torr
The state is maintained for 2 hours, and water is uniformly distributed in the casting block.
Ozone was absorbed. Then, exhaust was performed for one hour at the dehydrogenation temperature shown in Table 2.
And the atmosphere in the heat treatment furnace was changed to 1 × 10^-FiveTorr vacuum
Then, the above-mentioned cast block was subjected to a dehydrogenation treatment. afterwards
Ar gas was introduced into the furnace until it reached 1 atm,
The block is quenched and the Nd-Pr-Fe-B-based casting is permanent
I got a magnet. The structure of the obtained cast permanent magnet
Observe and check for the presence of recrystallized texture,
The results were measured and the results are shown in Table 2. [0052] [Table 2]From Table 2, it can be seen that the temperature: 700-1000 ° C. and water
When the element storage and dehydrogenation treatment are performed, the casting block
It was found to have recrystallization, especially at a temperature of 800 to 90.
In the hydrogen storage and dehydrogenation treatment in the range of 0 ° C, high magnetic
It can be seen that they have air characteristics. Examples 15 to 17 and Comparative Examples 11 and 12 Using Nd and Dy as rare earth elements,
The number of atoms of Nd-Dy-Fe-B system produced by solution and casting
Composition is Nd_14.8Dy_0.3Fe_78.1B_6.8Nd-D
A cast body of a y-Fe-B-based alloy was heated in an Ar gas atmosphere.
Degree: Perform homogenization treatment at 1080 ° C for 60 hours.
After cooling, length: 8mm x width: 8mm x height: 10
Cut into mm blocks. The cast block is heat treated.
Put in a furnace, 1 × 10^-FiveAfter evacuating to Torr vacuum,
The temperature is raised from room temperature to 830 ° C. in a vacuum, and the temperature is 830 ° C.
At 830 ° C for 1 hour.
After that, hydrogen gas was supplied at 0.2 Nl / min (temperature: 2
0 ° C) at a flow rate of 600 Torr into the heat treatment furnace.
Hydrogen gas while maintaining the inside at a hydrogen gas pressure: 600 Torr
To reduce the flow of hydrogen into the casting block.
Temperature: 830 ° C-hydrogen gas pressure: 600 Torr
For 10 hours to uniformly distribute hydrogen in the cast block.
And then evacuated at a temperature of 820 ° C.
The atmosphere of the furnace was set to a hydrogen gas pressure of 1 × 10^-6To
rr (Example 15), 1 × 10^-3Torr (Example 16), 1
× 10^-1Torr (Example 17), 2 × 10^-1Torr (Comparative example
11) and up to a vacuum of 1 Torr (Comparative Example 12)
The casting block was dehydrogenated. Then in the furnace
Ar gas is introduced until the pressure reaches 1 atm
Quenched, and Nd-Dy-Fe-B cast permanent magnet
I got The structure of the obtained cast permanent magnet was observed.
As a result, the above Examples 15 to 17 and Comparative Examples 11, 1
Recrystallization of all of the cast permanent magnets obtained in 2
Have joint tissues and measure their magnetic properties
The results are shown in Table 3. Table 3 shows that the cast permanent magnet of the present invention
Means that the hydrogen gas pressure is 1 × 10^-1
Excellent magnetic characteristics when dehydrogenation is completed at a pressure of Torr or less
It can be seen that it shows the property. [0057] [Table 3] Examples 18 to 19 and Comparative Examples 13 and 14 Examples 15 to 17 and Comparative Examples 11 and 12
Nd-Dy-Fe-B based alloy casting
Cut out the structure vertically: 8mm x width: 8mm x height: 10mm
Put the cast block into the heat treatment furnace^-FiveTorr
After evacuating to vacuum, Ar gas was allowed to flow in to 1 atm,
Temperature rise from room temperature to 830 ° C while flowing r gas
And hold at 830 ° C for 1 hour to reduce the temperature of the cast block.
After uniforming at 830 ° C., the Ar gas flow was stopped and water
Source gas is heated at a flow rate of 0.2 Nl / min (temperature: 20 ° C)
After flowing into the processing furnace, the inside of the furnace is replaced with hydrogen gas.
m, while flowing hydrogen gas.
The lock absorbs hydrogen, temperature: 830 ° C-hydrogen gas pressure
Force: Maintain the state of 1 atm for 10 hours.
After the hydrogen has been uniformly absorbed in the
Stop and let Ar gas flow again, and replace the inside of the furnace with Ar gas
Then, the furnace was kept for 30 minutes and the inside of the furnace was changed to an Ar gas atmosphere of 1 atm.
Was. At this time, the hydrogen gas still remains in the Ar gas atmosphere.
Was. Then, at a temperature of 820 ° C., the Ar gas
Atmosphere consisting of hydrogen gas and residual hydrogen gas
Pressure is 5 × 10^-FourTorr (Example 18), 8 × 10^-2Torr
(Example 19) 2 × 10^-1Torr (Comparative Example 13) and
Evacuation was performed until the pressure reached 1 Torr (Comparative Example 14).
The body block was dehydrogenated. Hydrogen gas partial pressure measurement
Is performed by gas chromatogram analysis, and the carrier gas is A
It was converted from the volume ratio of hydrogen gas using r. Then the furnace
Ar gas flows into the casting block until it reaches 1 atm.
Quenched to produce a Nd-Dy-Fe-B cast permanent magnet
Obtained. [0059] The permanent magnet of the cast body thus obtained.
All of the stones also have a recrystallized texture,
The magnetic properties of the permanent magnet were measured and the results are shown in Table 4.
Was. [0060] [Table 4] From Table 4, it can be seen that the above cast permanent magnet of the present invention was used.
Means that the hydrogen gas partial pressure is 1 × 10^-1
Excellent magnetic characteristics when dehydrogenation is completed at a pressure of Torr or less
It can be seen that it shows the property. [0062] As described above, the R-Fe-B of the present invention
Series cast permanent magnet is R_TwoFe₁₄The recrystallization of phase B gathers
Excellent magnetic properties due to the excellent recrystallized texture
By controlling the recrystallized grain size.
Improves magnetic properties, oxidation resistance, heat resistance, etc. of the structured permanent magnet
And maintain its magnetic properties even as a thin magnet
You can also. Further, the R—Fe—B cast body of the present invention
His magnets do not require sintering of R-Fe-B alloy powder.
In addition, the casting block is subject to hydrogen storage and dehydrogenation.
Therefore, R-Fe produced by sintering a conventional powder
-The manufacturing process is very simple compared to the method of manufacturing B-based permanent magnets
And have a significant effect on productivity and economics.
To bring.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram of a recrystallization texture obtained by growing the recrystallization of FIG. FIG. 2 is an explanatory view showing a structure in which a cast having the structure shown in FIG. 3 is processed to generate recrystallization of an R ₂ Fe ₁₄ B phase. FIG. 3 is an explanatory view of the structure of a cast of an R—Fe—B alloy. FIG. 4 is a heat treatment pattern of Example 1. FIG. 5 is a heat treatment pattern of Comparative Example 1. FIG. 6 is a heat treatment pattern of Comparative Example 2. FIG. 7 is an explanatory view of the structure of a conventional sintered magnet. 8 is a photograph of a metallographic structure of a cast permanent magnet obtained in Example 1 taken by a scanning electron microscope. FIG. FIG. 9 is a metallographic structure photograph of the homogenized cast body of Example 1 by a scanning electron microscope. [Explanation of Signs] 1 R ₂ Fe ₁₄ B phase 2 R-rich phase 3 B-rich phase 1 ′ Recrystallization of R ₂ Fe ₁₄ B phase

Claims (1)

(57) [Claims] Rare earth elements including Y (hereinafter, denoted by R), Fe and B
The permanent magnet made from casting of an R-Fe-B based alloy mainly, the average recrystallized grain size: take tetragonal structure 0.05~50μm R ₂ Fe ₁₄ recrystallization B intermetallic compound phase Rare earth element -Fe-B characterized by having a recrystallized texture in which
Series cast permanent magnet. 2. The rare-earth-Fe-B-based cast permanent magnet according to claim 1, wherein the recrystallized texture is surrounded by an R-rich phase.