JPH0199201A - Rare earth element-fe-b series cast permanent magnet and manufacture thereof - Google Patents

Abstract

PURPOSE:To improve magnetic properties, antioxidation, heat resistance, etc., of a cast permanent magnet by incorporating recrystalline composition containing R2Fe14B phase as a main phase in an R-Fe-B series cast permanent magnet. CONSTITUTION:An R-Fe-B series alloy cast containing as main ingredients rare earth element (R) including Y, Fe and B is formed. The composition of the cast is of recrystalline composition containing as a main phase R2Fe14B intermetallic compound phase 1 having a tetragonal structure including 0.05-50mum of mean recrystal particle size. Thus, the magnetic properties, antioxidation, heat resistance, etc., of the cast permanent magnet are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention has excellent magnetic properties. The present invention relates to a permanent magnet made of a rare earth element (hereinafter referred to as R)-Fe-B alloy cast body containing Y, and a method for manufacturing the same.

[Conventional technology]

R-Fe-B permanent magnets are attracting attention as magnets with particularly excellent magnetic properties among rare earth permanent magnets. The structure of the above-mentioned R-Fe-B permanent magnet is: - R2Fe14B intermetallic compound phase (hereinafter referred to as a R2Fe14B phase), which is a main phase with a ferromagnetic phase and a tetragonal structure (hereinafter referred to as a R2Fe14B phase);
-rich phase and B-rich phase.

The magnetic properties of the R-Fe-B permanent magnet greatly depend on the structure of the R-Pe-B permanent magnet, and the excellent magnetic properties of the R-Fθ-B alloy can be utilized. Permanent magnets with such a structure have been developed.

At present, as the above-mentioned R-Pe-B permanent magnets, there are the following.

(1) Permanent magnets characterized by sintered bodies produced by powder metallurgy (see, for example, Japanese Patent Publication No. 59-460008).

Permanent magnets featuring this sintered body (hereinafter referred to as sintered magnets) are produced by crushing an ingot or coarse powder of R-Pa-B alloy using various methods. This fine powder is molded into a green compact in a magnetic field or in the absence of a magnetic field. Next, the green compact is placed in a vacuum or in a non-oxidizing gas atmosphere.

The temperature was raised from room temperature, and the sintering temperature was 900 to 1200℃.
It is manufactured by sintering under conditions of holding for 0 to 120 minutes, and if necessary, subsequently performing heat treatment at an appropriate temperature to increase coercive force, followed by cooling. The magnetic properties of the above sintered magnet are 1 isotropic * BHmax =
l If it is about OMGOa or anisotropic, BH engineering
Indicates a value of c-30M()09 or higher.

The structure of the sintered magnet is as shown in FIG.

R2Pe14B phase 1, which is the main phase of the R-Fe-B permanent magnet, and B-rich3. And R2F1!114B phase 1
and R-rich present at the grain boundaries of B-rich phase 3.
Consists of phase 2. The R2FJ4B phase in Fig. 1 above is
In order to increase the coercive force, the average grain size is from several μm to 20 μm.
It is controlled by μ wings.

(2) Permanent magnets obtained by high-temperature compression and plastic processing of ribbon-shaped quenched powder by ultra-quenching method (e.g.,
(Refer to No. 0402) A permanent magnet (hereinafter referred to as a high-temperature compressed magnet) characterized by a substance obtained by compressing this rapidly solidified powder is first produced by R-F in a molten state.
It is manufactured by rapidly solidifying an e-B alloy to obtain a ribbon-shaped flake, heating it to a temperature of 2,700° C. or higher, performing high-temperature compression and Wi-ness processing for several minutes, and then cooling it.

The magnetic properties of the above-mentioned high-temperature compressed magnet are one isotropic.

BH Kitsune z-13 MGO13 degree, BHX11a knee 30 MGOe degree due to anisotropy by plastic working. The structure of the above-mentioned high-temperature compression magnet has a fine structure in which the main phase is an R2Fe14B phase with an average crystal grain size of several tens of nanometers to several hundreds of nanometers, and there is a KR-rich phase and an amorphous phase at the grain boundaries. The R2Fe14B phase, which is the main phase, is controlled to have a single domain grain size of 0.3 μm or less.

[Problem that the invention seeks to solve]

For rounding, R-IFe-B alloy becomes a permanent magnet with high coercive force.

(a) 0, in which the average crystal grain size of the R2Fe14B phase, which is the main phase, is 50μ or less, preferably single domain grains;
Must be 3μ or less.

(1)) There is no impurity or strain in the crystal grains or grain boundaries of the main phase, which can become nuclei when reversed magnetic domains occur.

(C) If the average crystal grain size of the R2Fe14B phase, which is the main phase, is from several micrometers to 50 micrometers, an I't-rich phase exists at the grain boundary of the R2Fe14B phase, and the above R2F
The crystal grains of the e14B phase are surrounded by the R-rtch phase.

(d) i! In the individual R2Fe and 4B phases of the stone powder, the easy axes of magnetization of crystal magnetic anisotropy are aligned and magnetic anisotropy is obtained.

It is believed that the average crystal grain size of the R2Fe14B phase, which is the main phase in (a) above, has a major influence on the coercive force.

Conventionally, R-XPe-B alloys were simply melted and cast.

Or, in the structure of a cast body that has been further homogenized,
Even after heat treatment, the main phase R2Fe14B remains in the tens of
Since it was not possible to control the magnetic field below μ islands, the cast body could not obtain excellent magnetic properties. For this reason, using a sintered magnet as in the conventional technique (1) above, and a high-temperature compressed magnet as in the conventional technique (2),
The structure of the R-Fa-B alloy was controlled.

The sintered magnet of the above conventional technology (1) has a main phase of R2P.
Since it is necessary to control the average crystal grain size of the e14B phase to within a few μm to 20 μm, the fine powder for sintering is prepared in consideration of the grain growth of the main phase in the sintering process.

Usually 3 to 4 μrttK must be crushed. However, R-IPe-B alloys for permanent magnets become very active when made into fine powder with a weight of S-4μ, so impurities such as oxides are generated in the sintered body, causing the magnetic field of the sintered magnet. The drawback was that the characteristics varied. Furthermore, as a permanent magnet, the R2Pe14B phase, which is the main phase, can form single-domain particles of 0.3 μm.
This is preferable, but the sintering method described above causes severe oxidation during pulverization and cannot be manufactured. In addition, the above-mentioned sintered magnet had the disadvantage that when it was in the shape of a thin plate with a thickness of 3 cranes or less, the magnetic properties decreased significantly as the thickness became thinner. In order to compensate for these shortcomings, measures have been taken such as adding additive elements to the above alloy, improving the sintering process, and coating the sintered magnet. In order to extract it, complicated processes and treatments had to be carried out.

The high-temperature compressed magnet of the above-mentioned conventional technology (2) becomes a permanent magnet only by high-temperature compression and plastic processing of the quenched powder, so its use is limited because the degree of freedom in the magnet shape is 1 yield. In addition, the R2F/t4B phase, which is the main phase of the microstructure, is formed by high-temperature compression and mechanical processing.

In order to cause grain growth and reduce coercive force, the above-mentioned high-temperature compression process must be carried out in a very short time of several minutes, and in order to obtain a permanent magnet with high magnetic properties, the manufacturing process is complicated. I had no choice but to do it.

That is, the R-F of the above conventional techniques (1) and (2)
All e-B series permanent magnets are produced by producing R-Fe-B series permanent magnets by sintering powder KL of -degree R-Pa-B series Sunstone alloy. There are problems in that it is difficult to handle the Fe-B alloy powder, and various precautions must be taken in the sintering method, making the manufacturing process complicated.

[Means for solving problems]

Therefore, the present inventors believe that if it is possible to impart excellent magnetic properties to cast bodies of R-F/-B alloys, which are said to be unable to obtain excellent magnetic properties, it would be possible to easily obtain excellent magnetic properties. Based on the idea that it is possible to manufacture an R-Fe-B permanent magnet with excellent magnetic properties, we conducted research to find an R-Fe-B cast permanent magnet with excellent magnetic properties.

Structure of a cast body of R-Fe-B alloy.

It was found that an R-Pa-B cast permanent magnet having excellent magnetic properties can be obtained by forming a recrystallized structure having R2Fe, 4B as the main phase.

This invention was made based on this knowledge.

The structure of a cast body of R-Fe-B alloy.

Average recrystallized grain size: 0.05-50μ blade R2Pe14
This is a rare earth-Fe-B cast permanent magnet having a recrystallized structure with B phase as the main phase.

The above-mentioned crystalline structure will be explained based on FIG. 2.

Figure tJ12 (a) is a schematic diagram of the structure of a cast body obtained by casting an R-re-B magnet alloy. Above figure 2(a)
In, 1 is R21'! 114B phase, 2 is R-ric
It is h phase. R-rich phase 2 is a main phase of R2Fe
14B phase 1 exists mainly at grain boundaries. Figure 2 above (a
) When the cast body shown in ) is processed under appropriate conditions, it becomes lc R2Pe14 as shown in Fig. 2(b) K.
Recrystallization 1' of the B phase occurs within the grains or at the grain boundaries of the B phase 1, and these recrystallize as shown in Fig. 2(e).
The result is a recrystallized 1' texture of R2Fe, 4B phase as shown in K.

FIG. 2(b) above is a schematic diagram of the structure of the cast body shown in FIG. 2(a) K at the time when the recrystallization 1' of the *R2F614B phase begins to occur. FIG. 2(C) is a schematic diagram showing the structure of the cast body after the processing of the cast body shown in FIG. 2(a) is completed.

Here, the R2Fli114B phase 1 of the R-Fa-B alloy shown in FIG. 2(a) and the recrystallized KR2F614B phase 1' shown in FIG. This is shown in FIG. 2(C). More R2Pe
14 Even if the texture consists of recrystallized 1' of B phase,
R formed in FIG. 2 (1)) and (C) above
The recrystallization 1' of the 2Pe14B phase does not have a completely random crystal orientation within the region of the individual R2Fe, 4B phase 1 of the 21M(a).

It is an organization with a certain orientation.

On the other hand, the R-rich phase is not obvious at the early stage of the recrystallization of the R2Fe14B phase as shown in Figure 2(b), but as the recrystallized 1' of the R2Fe14B phase grows and it is shown in Figure 2(C). Average grain size of recrystallized grains shown in: 0.05μ
When the texture becomes worse than the proverbial texture, it precipitates mainly at the grain boundaries of the recrystallized grains 1'.

The present invention is directed to the R-Fe having the recrystallized 1' of the 12Fe14B phase shown in the above 's2 diagram (11)) and (C).
The present invention is characterized by an R-Fe-B cast body permanent magnet made of a cast body of a -B alloy.

Therefore, the R-Fe-B cast permanent magnet of the present invention is a cast body having a recrystallized structure, whereas the R-Fe-B permanent magnets of conventional techniques (1) and (2) ,
It is completely different in that it does not have a recrystallized structure and is a material obtained by compressing a sintered body or rapidly solidified powder.

The reason why the R-Fe-B permanent magnet of B's invention exhibits a high coercive force is that the recrystallized grain size of the R2Fe14B phase, which is the main phase, is 5.
0μ layer or less, preferably 0,3 which can be single domain particles
This is because the recrystallized grains have no impurities or strain inside the grains or at the grain boundaries, and an R-rich phase exists at the grain boundaries. be. Above R2F
If the average recrystallized grain size of the e14B phase is smaller than 0.05 μ, magnetization becomes difficult and impractical, but if it is larger than 50 µ, it will only show a low coercive force, and R has excellent magnetic properties. -It cannot be said to be an IPe-B permanent magnet.

In addition, a part of Pa of the R-re-B cast permanent magnet having a recrystallized structure with R2Fe14B phase as the main phase of this invention is Co, Ni, Cr, Mo, W, Ti, Zr, H.
1 or 28 of f may be replaced with a small amount or more.

The method for obtaining the above-mentioned recrystallized structure is generally as follows.

After incorporating strains such as high-density dislocations and vacancies inside the material,
A method of generating and growing recrystallization by performing an appropriate heat treatment is known, but in order to generate a recrystallized structure in a cast body of the above-mentioned R-Fθ-B magnet alloy, it is necessary to heat R2 at an appropriate temperature.
By occluding hydrogen into the Fe14B phase to give lattice strain and then dehydrogenating it at an appropriate temperature, *R2Fe14
It was found that it is most preferable to eliminate the brittle fractures of the B phase, recover the structure, and generate and grow recrystallization.

The manufacturing method of the present invention was developed based on this knowledge.

A cast body of an R-Fe-B alloy is held at a temperature of 700 to 1000°C in a hydrogen gas atmosphere to absorb hydrogen into the cast body, and then heated with a hydrogen gas pressure crab 1X10 at a temperature of 700 to 1000 °C. (By performing dehydrogenation treatment in a non-oxidizing atmosphere with hydrogen gas partial pressure: 1XIO'rorr or less and then cooling heat treatment) * Recrystallized structure with R2Fe, 4El phase as the main phase This method is characterized by a method for obtaining an R-Pe-B cast permanent magnet having the following characteristics.

Therefore, in the method for manufacturing a permanent magnet of this invention, R
The fact that a permanent magnet can be obtained from a cast body of -Fe-B alloy is completely different from the conventional manufacturing method of R-Pa -B-based permanent magnet, and furthermore, it is completely different from the conventional manufacturing method of R-Pa-B-based permanent magnet. The manufacturing process is very simple compared to the manufacturing method of .

In the production method of the present invention, the hydrogen gas atmosphere includes a mixed gas atmosphere of hydrogen gas and other inert gases. The hydrogen gas pressure must be such that the Fj2Fe1'4 B phase absorbs hydrogen and gives sufficient lattice strain to cause recrystallization, and the hydrogen gas pressure must be at least O,
If the atmosphere is a mixed gas of hydrogen gas and another inert gas, the partial pressure of hydrogen gas must be at least 0.1 Torr.

In addition, hydrogen is added to the R2Fe14B phase e, IIl! , and the temperature at which the dehydrogenation treatment is performed is as low as 700°C.

When storing hydrogen, the cast body will crack and become brittle.
During the dehydrogenation process, hydrogen remains and significantly reduces the magnetic properties. Furthermore, if the temperature at which hydrogen is stored in the K, 12Fe14 B phase and the temperature at which the dehydrogenation treatment is performed is higher than 1000°C, the generation and growth of recrystallization is extremely fast, making it difficult to control the recrystallized grains to 5 opts+ or less. It is.

R-Fe- in a hydrogen gas atmosphere at a temperature lower than 700°C.
If a cast body of B-based magnetic alloy is placed, the cast body will crack and become brittle, so the atmosphere during the heating up to 700 t must be a hydrogen-free vacuum or an inert gas atmosphere.

When performing dehydrogenation treatment, the hydrogen gas pressure is lXl0"'!
When the dehydrogenation process is completed at a pressure above 'orr, hydrogen remains in the cast body and the magnetic properties deteriorate.

〔Example〕

Next, this invention will be specifically explained based on Examples, and how excellent effects this invention can achieve will be explained using Comparative Examples.

Example 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.
14.1]F'1177.188.1 Nd-Fe
-A cast body of B-based alloy is placed in an Ar gas atmosphere at a temperature of 1 l.
After homogenization treatment was carried out under the conditions of holding at OO°C for 40 hours and cooling, it was cut into blocks of 8 parrots (vertical) x 8 parrots (width) x 10 parrots (height).

This cast block was placed in a heat treatment furnace, and
After evacuation to a vacuum of orr, the temperature was raised from room temperature to 2810°C in the vacuum, and held at 810°C for 30 minutes to make the temperature of the cast block uniform at 810°C.
Hydrogen gas was supplied at a flow rate of INt/ail (temperature: 2°C).
The hydrogen gas pressure in the furnace is increased to latmKa! Hydrogen gas is allowed to flow while holding the cast block to store hydrogen at a temperature of 8.
After maintaining the condition of 10°C and hydrogen gas pressure of 1 atm for 5 hours to uniformly absorb hydrogen in the above cast block, exhaust was performed at a temperature of 810°C for 1 hour to change the atmosphere in the heat treatment furnace. The above cast block was subjected to dehydrogenation treatment under a vacuum of IX I O'rorr. After that, x in the furnace
The cast block was rapidly cooled by flowing Ar gas until the temperature reached ATM to obtain a Nd-Fs-B cast permanent magnet.

FIG. 3 shows the Nd-Fe-B of the present invention in Example 1 above.
A heat treatment pattern for obtaining a recrystallized structure of a cast permanent magnet is shown.

The obtained cast permanent magnet is crushed to obtain a particle size of 20
When X-ray diffraction was performed using this powder, it was observed that the diffraction lines of the main phase, Nd2Fe14 B phase, and the Nd-rich phase were clearly visible.

In addition, the structure of the cast permanent magnet was observed using a scanning electron microscope, and EPMA (electron probe microfraction fold fIt)
Compositional analysis was performed using

FIG. 4(a) shows a scanning electron micrograph of the cast permanent magnet obtained in this example. FIG. 4(b) K S
A scanning electron micrograph of the above-mentioned cast body which has only been subjected to the homogenization treatment in Example 1 is shown.

As a result of compositional analysis using E PMA (electron probe microanalyzer), the bases in the scanning electron micrographs in Figures 4(a) and (b) are both Nd2Fe14B phase, and there is Nd-rich at the grain boundaries. phase existed. Nd of the cast body after the homogenization treatment shown in Figure 4 (1)) above
The 2Fe14B phase was coarse deadrite-like crystal grains weighing several tens to several thousand micrometers. The cast permanent magnet obtained in Example 1 shown in FIG. 4(a) has a main phase of N.
(It was found that the 12Fe 14 B phase has fine crystal grains with a diameter of about 1.5μ, and the results of composition analysis using EPMA (electron probe microanalyzer) also show that the recrystallized grains are Nd2
It was confirmed that it was Fe14 B phase.

Therefore, from FIG. 4(a) above, the cast permanent magnet of the present invention does not have a simple cast structure, but has a large number of recrystallized grains of the new Nd2F1!114B phase of about 1.5 μm. It can be seen that it has a recrystallized structure.

Furthermore, it can be seen that this recrystallized structure can be obtained by performing the heat treatment shown in FIG.

Table 1 shows the results of the magnetic properties of the permanent magnet obtained in Example 1 above.

Comparative examples 1 and 2 The same homogenization treatment as in Example 1 above was performed.

A cast block of length: 8mm x width: 8MX x height: 10 pieces was placed in a heat treatment furnace, evacuated to a vacuum of 1X10 Torr, and then heated from room temperature to 810℃ in the vacuum. After holding for 30 minutes to make the temperature of the cast block uniform at 810℃, Ar gas was added to lNtlW.
Ar gas is flowed into the heat treatment furnace at a flow rate of iL (20℃) up to latm, and Ar gas is flowed while maintaining the inside of the furnace at latm, and the temperature is 2810℃ - Ar gas pressure crab l
After maintaining ATM condition for 5 hours, temperature: 810℃
The atmosphere inside the heat treatment furnace was evacuated for 1 hour to
The vacuum was OTorr. Thereafter, Ar gas was introduced into the furnace until the temperature reached latm, and the cast block was rapidly cooled to obtain a Nd-ye-B cast permanent magnet (Comparative Example 1).
).

Further, in the heat treatment of Example 1, a heat treatment similar to that of Example 1 was performed in a vacuum of 1X10 Torr without using hydrogen gas to obtain an Nd-Fe-B cast permanent magnet (Comparative Example 2). ).

The heat treatment patterns of Comparative Examples 1 and 2 are shown in FIGS. 3' and 3'.

The structure of the cast permanent stone obtained in Comparative Examples 1 and 2 is similar to the structure shown in FIG. 4(b).

The main phase (D Nd 2 F s 14 B phase) had deadrite-like coarse crystal grains.

Table 1 also shows the results of the magnetic properties of the cast rod permanent magnets obtained in Comparative Examples 1 and 2 above.

From Table 1, it can be seen that the cast bar permanent magnet of this invention has a coercive force of 1.
It can be seen that it exhibits excellent magnetic properties with a high value of 2.5 KOe.

Table 1 Examples 2 to 10 and Comparative Examples 3 to 5 Using Nd and Pr as rare earth elements, the atomic composition of the Nd-Pr-Fe-B system manufactured by melting and casting in an electron beam melting furnace was Nd14jPrllJFe78. 4 B
A cast body of an N(1-F'r-Fe-B-based alloy) having a molecular weight of 4.7 was cut into blocks with vertical dimensions of 2B HX width: 8wX height=10.

This cast block was placed in a heat treatment furnace, and 2XIO"'T
From room temperature in that vacuum after evacuation to orr vacuum.

After raising the temperature to the hydrogen storage temperature shown in Table 2 and holding it for 30 minutes at the hydrogen storage temperature shown in Table 2 to make the temperature of the cast block uniform, hydrogen gas was heated to 0.6 NLl lj& (temperature:
20°C) until the hydrogen gas pressure reaches 500 Torr.
o 0 Torr K #a, hydrogen gas is allowed to flow under reduced pressure to absorb hydrogen into the cast block, and the hydrogen storage temperature - hydrogen gas pressure crab S OOTo shown in Table 2 above is applied.
The rT state was maintained for 2 hours to uniformly store hydrogen in the cast block.

Next, the atmosphere in the heat treatment furnace was reduced to l
The cast block was subjected to dehydrogenation treatment under a vacuum of r. Thereafter, Ar gas was introduced into the furnace until the temperature reached 1 atm to rapidly cool the cast block, and N(1-Pr-
? - A B-based cast permanent magnet was obtained. The structure of the obtained cast permanent magnet was observed, the presence or absence of a recrystallized structure was examined, and the magnetic properties were measured. The results are shown in Table 2.

From Table 2 above, when hydrogen absorption and dehydrogenation treatment is carried out at a temperature of 00 to 1000°C, the cast block has recrystallized cores, special tC@: 800 to 900°C.
It can be seen that it has high magnetic properties in the range of hydrogen I&F and dehydrogenation treatment.

Examples 15 to l) and Comparative Example 11.12 The atomic composition of the Nd-Dy-Pa-B system manufactured by melting and casting Nd and D7 as rare earth elements in a high-frequency melting furnace is Nd.
zi, 5Dys, sF! Nd which is ys, t Ba, a
-Dy -Fe-B alloy casting was homogenized and cooled in an Ar gas atmosphere under the conditions of @ degree: 1 O 1 iOC - 60 hours, and then vertical: awxx horizontal = 80
× It was cut into blocks with a height of 210 m. This cast block is placed in a heat treatment furnace, and lXl0 'I'or
After evacuating to a vacuum of r, the temperature from room temperature to 830C
After raising the temperature to 53°C and holding it for 1 hour to make the temperature of the cast body uniform at 830°C, hydrogen gas was heated to 600 Torr at a flow rate of O, fl NA /IIA (temperature: 20C). The cast block was allowed to absorb hydrogen by flowing the hydrogen gas under reduced pressure while maintaining the hydrogen gas pressure in the furnace at 600 TorrK #1. Temperature = 830°C - Hydrogen gas pressure = 600 Torr
Hold the rr state for 10 hours and uniformly introduce hydrogen into the above cast body. After 7R, temperature = 820℃
The atmosphere inside the heat treatment furnace was evacuated using a hydrogen gas pressure crab l X I O” Torr (Example 115).
), 1X10'l'orr (Example 16), LX
l 0'''Torr (Example 1?), zxlo
The above cast block was subjected to dehydrogenation Jl until a vacuum of -"rorr (Comparative Example 1m) and l〒orr (Comparative Example 12) was reached. Thereafter, A
The cast block is rapidly cooled by flowing r gas into Nd-
A Dy-Pa-B cast permanent magnet was obtained.

When the structures of the obtained cast permanent magnets were observed, all of the cast permanent magnets obtained in Examples 15 to 1 and Comparative Examples 11 and 12 had a recrystallized structure. Measure their magnetic properties and send the results to the third
Shown in the table.

From Table 3 above, it can be seen that the cast permanent magnet of the present invention has a hydrogen gas pressure of 1 x 10-1To when dehydrogenating.
It can be seen that excellent magnetic properties are exhibited when the dehydrogenation treatment is completed at a pressure below rr.

Table 3 Examples 18-19 and Comparative Examples 13.14 Above Example 1
In 5 to 1 and Comparative Example 11.12, the Nd-Dy-re-B alloy castings subjected to homogenization treatment:
8 m x width: B parrot x height: 1 O A cast block cut into a parrot size was placed in a heat treatment furnace.

After evacuation to a vacuum of l X I O'l"orr, la
Ar gas was introduced at tmt, the temperature was raised from room temperature to 830°C while Ar gas was flowing at 7a, and the temperature was maintained at 830°C for 1 hour to make the temperature of the cast block uniform at 830C. Stop and add hydrogen gas to 0.2Nt/
It flows into the heat treatment furnace at a flow rate of 1 IilL (temperature = 20 ° C.), replaces the inside of the furnace with hydrogen gas, maintains the inside of the furnace at 1 atm Ic, and causes the hydrogen gas to flow into the cast block, and the temperature :B: After holding the condition at 30°C and hydrogen gas pressure for 10 hours to uniformly store hydrogen in the cast block.

Stop the hydrogen gas flow and let Ar gas flow in again.

Replace the Ar gas in the furnace, hold it for 30 minutes, and then turn the inside of the furnace 1ain.
The atmosphere was set to Ar gas atmosphere. At this time, as much as Kt of hydrogen gas remained in the gas atmosphere. After that, the temperature was 2820℃.
The hydrogen gas partial pressure of the atmosphere consisting of Ar gas and residual hydrogen gas in the heat treatment furnace was 5 x 10 Torr (Example 18) and 8 x 10-2 Torr (Example 19), respectively.
), 2XIOTorr (Comparative Example 13) and l
Torr (Comparative Example 14) The cast block was dehydrogenated by evacuation. Hydrogen gas partial pressure was measured using gas chromatograph Duram analysis.

The carrier gas was converted from the volume ratio of hydrogen gas using Ar. After that, Ar gas was introduced into the furnace until the temperature reached 1 atmK, and the cast body was rapidly cooled down to Nd-D7-re-B.
A cast permanent magnet was obtained.

The cast permanent magnets obtained in this manner all had a recrystallized structure, and the magnetic properties of these cast permanent magnets were measured and the results are shown in Table 4.

Table 4 above! From @Table 4, the above-mentioned cast permanent stone of this invention is:
When performing dehydrogenation treatment, the hydrogen gas partial pressure is
It can be seen that excellent magnetic properties are exhibited when the dehydrogenation treatment is completed at a pressure below orr.

〔Effect of the invention〕

As mentioned above, the R-Fe-B based cast permanent magnet of the present invention has a recrystallized structure with the R2F/t4B phase as the main phase, so it exhibits excellent magnetic properties and also has a recrystallized grain size. Through control, the magnetic properties, oxidation resistance, heat resistance, etc. of the cast permanent magnet can also be improved, and the magnetic properties can also be maintained as a thin plate magnet.

Further, the R-Fe-B cast permanent magnet of the present invention has R
-Without sintering Fe-B alloy powder.

Since the cast boot stock is subjected to hydrogen exposure and dehydrogenation treatment, R-F・-B manufactured by sintering conventional powder is used.
Compared to the manufacturing method of permanent magnets, this method is much simpler to manufacture and has excellent productivity and economic efficiency.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the structure of a conventional sintered magnet. FIG. 2 fat is an explanatory diagram of the structure of a cast body of R-bar B alloy. tJz diagram (bl is Fig. 2 (a) Ic is an explanatory diagram showing the structure in which recrystallization of the R2Fe14B phase is generated by processing a cast body having the structure shown. Fig. 2 (el is Fig. 2) An explanatory diagram of the recrystallized texture obtained by growing the recrystallized structure in (b). Figure 3 is the heat treatment pattern of Example 1. Figure 3' is the heat treatment pattern of Comparative Example 1. The figure shows the heat treatment pattern of Comparative Example 2. Figure 4 (&) is a scanning electron micrograph of the cast permanent magnet obtained from Example 1K. Figure 4 (b) B h Homogenization of Example 1 A scanning micrograph of the treated casting is shown. 1"-12Pa14B phase, 2-R-rioh
#a. 3 = B - rich phase, 1' - recrystallized 12F
I114B phase. Presenter Mitsubishi Metals Co., Ltd. agent Tomi 1) Kazuo and 1 other person 1: R2F
er48 years old 2: R-rtchJFm Fig. 1 (o) μm (b) 2 μm Fig. 4 (a) (b) Sleeping 2 Fig. 4: RzFet4B 2: R-rich Shifz R2FmBJ8 hands
(continued amendment writing method) January 2, 1986
8th 1, Indication of the case, Patent Application No. 62-257669 2, Name of the invention: Rare earth-Fe-B cast permanent magnet, and its manufacturing method a. Person making the amendment: Relationship with the case. Patent applicant address: Chiyoda, Tokyo. 5-2, Otemachi-ku, Tokyo Name (Name) (626) Mitsubishi Metals Co., Ltd. Representative: Ken Nagano 4, Agent address: 8th floor, 5th floor, Soho Daini Building, 23-chome, Kanda Nishikicho, Chiyoda-ku, Tokyo, amended Date of Directive: January 26, 1986 (Despatch Mill) 6. "Detailed Description of the Invention" of the specification subject to amendment and Figure 1 (1) Clear ll
1iI, page 19, lines 8 to 9 [Figure 3' and 3
"Figure 3-1 and Figure 3-2" should be corrected. (2) On page 29, line 5 of the specification, the phrase ``Figure 3'is'' is corrected to ``Figure 3-1 is''. (3) In the 6th line of page 29 of Akira 1IllS, the statement ``Figure 3'' is corrected to ``Figure 3-2 is''. (4) On page 29, line 8 of the specification, ``Scanning electron micrograph,'' [ has been corrected to read ``Metal structure photograph by scanning electron microscope.'' (5) On page 29, line 10 of the specification, the phrase "scanning micrograph" is corrected to "metallic structure photograph taken with a scanning electron microscope." (6) Figures 3, 3' and 3'' of the drawings are
3-1 and 3-2. that's all

Claims (3)

[Claims] (1) The structure of a cast body of an R-Fe-B alloy whose main components are a rare earth element containing Y (hereinafter referred to as R), Fe, and B is square with an average recrystallized grain size of 0.05 to 50 μm. A rare earth-Fe-B cast permanent magnet characterized by having a recrystallized structure having an R_2Fe_1_4B intermetallic compound phase as a main phase. (2) A cast body of a rare earth-Fe-B alloy containing R, Fe, and B as main components was heated to a temperature of 700 to 1000°C in a hydrogen gas atmosphere.
Temperature: 700-1000°C, Hydrogen gas pressure: 1×10
^-^ 1 Torr or less or hydrogen gas partial pressure: 1 x 10^
−^ Dehydrogenation treatment in a non-oxidizing atmosphere of 1 Torr or less,
A method for manufacturing a rare earth-Fe-B cast permanent magnet, characterized in that the permanent magnet is then cooled. (3) Rare earth-Fe-B according to claim 2, characterized in that the atmosphere during the temperature increase from 700 to 1000°C is a vacuum or inert gas atmosphere without hydrogen. A method for producing cast permanent magnets.