JP3288571B2 - Method for producing bulk compact of amorphous alloy powder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a bulk compact of an amorphous alloy powder.

[0002]

2. Description of the Related Art Amorphous magnetic alloys are known to exhibit excellent properties in terms of high corrosion resistance, high wear resistance, high strength, high magnetic permeability, etc., as compared with crystalline materials. However, the shape of this amorphous alloy is limited to a ribbon shape and a thin line shape, with some exceptions, due to a manufacturing process for securing an amorphous state. For this reason, recently, a method of producing a molded article of an arbitrary shape from powder has been studied. In the case of an amorphous alloy powder, in order to maintain the amorphous state, it is impossible to diffuse and join metals at a temperature higher than the crystallization temperature as in a general sintered body. That is, since the forming of the alloy must be performed at a temperature lower than the crystallization temperature,
In a pressure sintering method such as hot pressing or HIP (hot isostatic pressing), it has been difficult to make amorphous alloy powders into bulk.

As a method of forming a bulk body from an amorphous alloy powder, an explosive method, an impact gun method, and the like can be cited. However, these methods require special equipment to obtain a very large energy. In addition, there is a problem that the molding process is complicated and productivity is low.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to produce a bulk compact from an amorphous alloy powder by a pressure sintering method.

[0005]

In order to achieve the above-mentioned object, the present invention provides a mixed powder of an amorphous alloy powder and a glass powder having a softening point lower than the crystallization temperature of the amorphous alloy. By sintering under pressure at a temperature higher than the softening point of the glass and lower than the crystallization temperature of the amorphous alloy, the softened glass acts as a binder, and the particles of the amorphous alloy pass through the glass. By joining, the amorphous alloy powder can be made into a bulk.

[0006] The mixing amount of glass is desirably 3 to 20 vol%. If the mixing amount of the glass is too small, the amorphous alloy powder cannot be made into a bulk.On the other hand, if the mixing amount is increased, the bonding strength increases, but the amount of the amorphous alloy in the compact is reduced. This is because it becomes impossible to secure sufficient characteristics. Note that the bonding strength of the bulk molded body is enough that the shape does not collapse when machining such as drilling is performed.

[0007] As alloys that are desired to be used in an amorphous state, alloys such as Fe-based and Co-based can be given. The crystallization temperature of these alloys is usually around 500 ° C. A glass having a softening point lower than the crystallization temperature of the amorphous alloy is used, and for example, a glass having a softening point lower by about 100 to 200 ° C. is desirably used. This is because a range of the sintering temperature is given a range when performing pressure sintering. As a suitable glass material, a borate-based glass containing lead oxide (PbO.B ₂ O
Glasses having a low softening point, such as ₃ ).

[0008]

[Function] In the pressure sintering of the mixed powder of the amorphous alloy powder and the glass powder, the heating temperature is lower than the crystallization temperature of the amorphous alloy, so that the amorphous alloy maintains the amorphous state. Is done. On the other hand, since the sintering heating temperature is higher than the softening point of the glass, when a pressure is applied at that temperature, the softened glass powder penetrates almost without gaps between the amorphous alloy particles. After cooling, the glass hardens and plays a role as a binder for the amorphous alloy powder, and the sintered product is bulked to obtain a high-density compact.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION A powder of an amorphous alloy is prepared by melting a raw material alloy at a temperature of about 50 to 200 ° C. higher than its melting point, for example, by a high speed rotating water flow method at a high cooling rate of about 10 ⁵ K / sec or more. It can be produced by quenching. In addition,
The high-speed rotation water flow method is to form a cooling water layer that flows down while rotating on the inner peripheral surface of the cooling cylinder, supply a jet of a molten metal flow to the cooling water layer, and rotate A method of obtaining a metal powder by dividing and rapidly solidifying (see JP-A-4-14-1)
7605), which is excellent in mass productivity.

The particle size of the amorphous alloy powder is set to about 250 μm or less in order to secure the amorphous property, and the average particle size is about 100 to 100 μm.
150 μm is preferred.

[0011] The low softening point glass powder is preferably smaller than about 1/20 of the average particle size of the amorphous alloy powder so that it can enter between the particles of the amorphous alloy powder. . For an amorphous alloy powder having a particle diameter of about 250 μm or less and an average particle diameter of about 100 to 150 μm, the particle diameter of the glass powder is about 10 μm or less, and the average particle diameter is about 1 to 7 μm.
Is preferred. When the glass powder is mixed with the amorphous alloy powder in a ball mill, the glass powder is pulverized and refined in the stirring process. Frequently, the particle size can be adjusted by the stirring time.

[0012]

EXAMPLE 1 In this example, bulk molding of amorphous Fe-based alloy powder is performed by hot pressing. An amorphous alloy powder of Fe ₇₈ Si ₉ B ₁₃ was produced by the high-speed rotating water flow method described above. The average particle size of the amorphous alloy powder of Fe ₇₈ Si ₉ B ₁₃ is about 150 μm. Incidentally, the crystallization starting temperature of Fe7 ₈ Si ₉ B ₁₃ is about 470 ° C.. This Fe ₇₈ Si ₉ B ₁₃
Of amorphous alloy powder and glass (borate-based glass containing lead oxide) having a softening point of about 320 ° C. in a ball mill at a mixing ratio (volume ratio) of 97: 3 for 24 hours. did. The average particle size of the glass powder after mixing is about 1-2 μm. This mixed powder is subjected to a pressure of 1.6 GPa and a temperature of 450 ° C. (a temperature not lower than the softening point of glass and not higher than the crystallization temperature of the Fe alloy).
Under the conditions described above, hot pressing was performed within 1 minute to obtain a cylindrical molded body having a diameter of 20 mm and a length of 10 mm. The obtained compact is bulked, and its relative density is 9
5%. The “relative density” is obtained as a ratio of an actual weight to a weight when the cylindrical molded body is assumed to be a perfect dense body. The weight of a perfectly dense body is
This is a value calculated based on the mixing ratio between the amorphous alloy powder and the glass powder.

In order to compare the bulking, hot pressing was performed under the conditions of a pressure of 1.6 GPa and a temperature of 450 ° C. only with an amorphous alloy powder of Fe ₇₈ Si ₉ B ₁₃ without adding glass powder. However, when an external force is applied to the molded body removed from the press die, it collapses easily and is not bulky.

Next, in order to compare the crystal structures, hot pressing was performed under the conditions of a pressure of 1.6 GPa and a temperature of 900 ° C. only with an amorphous alloy powder of Fe ₇₈ Si ₉ B ₁₃ without adding glass powder. Thus, a compact having a crystal structure was produced. An X-ray diffraction pattern of each of the compact having the crystal structure, the amorphous alloy powder, and the compact obtained by hot pressing the mixed powder of the amorphous alloy powder and the glass powder at a temperature of 450 ° C. was examined. The result is shown in FIG. As is clear from FIG. 1, in the compact hot-pressed at a temperature of 900 ° C., peaks indicating the crystal structure are observed at several places, whereas 450 μm of the mixed powder of the amorphous alloy powder and the glass powder is used. ° C
The green compact hot-pressed at the temperature of the above has substantially the same X-ray diffraction pattern as that of the amorphous powder, indicating that it is in an amorphous state.

Embodiment 2 In this embodiment, bulk molding of an amorphous Co-based alloy powder is performed by hot pressing. In the same manner as in Example 1, (Co _0.95 Fe _0.05 ) ₇₅ (S
The amorphous alloy powder of i _0.6 B _{0. 4) 25} was prepared. (Co _0.95
The average particle size of the amorphous alloy powder of _{Fe 0.05) 75 (Si 0.6 B} 0.4) 25 is about 150 [mu] m. Note that (Co _0.95 Fe _0.05 )
The crystallization onset temperature of ₇₅ (Si _0.6 B _0.4 ) ₂₅ is about 490 ° C. This amorphous alloy powder and glass powder having a softening point of about 320 ° C. were stirred and mixed in a ball mill at a mixing ratio (volume ratio) of 97: 3 for 24 hours. The average particle size of the glass powder after mixing is about 1-2 μm. This mixed powder is pressed at a pressure of 1.
Under a condition of 6 GPa and a temperature of 450 ° C. (a temperature equal to or higher than the softening point of glass and equal to or lower than the crystallization temperature of the Co alloy), a hot press is performed within 1 minute within a period of 1 minute, and a cylindrical molded body having a diameter of 20 mm and a length of 10 mm I got The obtained compact was bulked, and its relative density was 95%.

In order to compare the bulking, an amorphous alloy powder of (Co _0.95 Fe _0.05 ) ₇₅ (Si _0.6 B _0.4 ) ₂₅ was similarly added without adding glass powder, and the pressure was similarly set to 1.6 GPa. Hot pressing was performed at a temperature of 450 ° C. However, when an external force is applied to the molded body removed from the press die, it collapses easily and is not bulky.

Furthermore, in order to compare the crystal structure, the glass powder is not _{added, (Co 0.95 Fe 0 .05)} 75 (Si 0.6 B
_0.4 ) ₂₅ amorphous alloy powder only, pressure 1.6 GPa, temperature 90
Hot pressing was performed under the condition of 0 ° C. to produce a compact having a crystal structure. A compact having this crystal structure, an amorphous alloy powder, and a mixed powder of an amorphous alloy powder and a glass powder
An X-ray diffraction pattern was examined for each of the compacts hot-pressed at a temperature of 50 ° C. The result is shown in FIG. As is clear from FIG. 2, in the compact hot-pressed at a temperature of 900 ° C., peaks indicating the crystal structure are observed at several places, whereas 450 μm of the mixed powder of the amorphous alloy powder and the glass powder is used. The compact hot-pressed at a temperature of ° C. has almost the same X-ray diffraction pattern as that of the amorphous powder, indicating that it is in an amorphous state.

Embodiment 3 In this embodiment, bulk molding of an amorphous Fe-based alloy powder is performed by HIP. Amorphous alloy powder of Fe ₇₈ Si ₉ B ₁₃ was the same as used in Example 1. This amorphous alloy powder and glass powder having a softening point of about 320 ° C. were stirred and mixed in a ball mill at a mixing ratio (volume ratio) of 95: 5 for 24 hours. The average particle size of the glass powder after mixing is about 1-2 μm. This mixed powder was charged in a capsule can, and after degassing and sealing, sintering by HIP was performed within 1 minute under the conditions of a pressure of 176 MPa and a temperature of 450 ° C. to form a cylindrical shape having a diameter of 30 mm and a length of 40 mm. I got a body. The obtained compact is bulked and has a relative density of 8
5%. Next, sintering by HIP was performed under the conditions of a pressure of 980 MPa and a temperature of 450 ° C. within a period of one minute or less. The obtained compact was bulked, and its relative density was 97%. FIG. 3 shows the microstructure of this bulk compact. In FIG. 3, white portions represent amorphous alloy particles, and black portions represent glass. As shown in FIG. 3, the particles of the amorphous alloy are in a somewhat crushed state,
It can be seen that they are joined via the glass. These two
When the X-ray diffraction patterns of the two bulk compacts were examined in the same manner as in Examples 1 and 2, it was confirmed that the two bulk compacts were in an amorphous state.

For comparison of bulking, no glass powder was added, and only the amorphous alloy powder of Fe ₇₈ Si ₉ B ₁₃ was used.
Similarly, at a pressure of 980 MPa and a temperature of 450 ° C., HI
By sintering with P, a cylindrical molded body was produced. However, when an external force is applied to the molded body removed from the press die, the molded body is easily collapsed and is not bulked.

[0020]

According to the present invention, the amorphous alloy powder can be formed into a bulk compact by the pressure sintering method.
It can be applied to devices of various shapes requiring magnetism. When the bulk compact is used for a high-frequency power device, it is necessary to perform high filling molding in order to obtain a certain or higher magnetic permeability. In this case, the amount of glass powder to be added may be reduced. On the other hand, when used for applications where securing insulation between particles is important to suppress eddy current loss,
Since glass serves as an insulating material, the amount of glass powder added may be increased. As described above, according to the present invention, it is possible to produce a desired amorphous bulk molded body by adjusting the amount of glass powder to be added according to various required properties.

[Brief description of the drawings]

FIG. 1 is a view showing an X-ray diffraction pattern of a bulk compact of an Fe-based amorphous alloy powder.

FIG. 2 is a view showing an X-ray diffraction pattern of a bulk compact of a Co-based amorphous alloy powder.

FIG. 3 is a view showing a microstructure of a bulk compact obtained by HIPing a mixed powder of a glass powder and an amorphous alloy powder of Fe ₇₈ Si ₉ B ₁₃ under the conditions of a pressure of 980 MPa and a temperature of 450 ° C. .

Continued on the front page (72) Inventor Hiroshi Yamamoto 1-1-1, Hama, Amagasaki-shi, Hyogo Prefecture Inside Kubota Technology Development Laboratory Co., Ltd. (72) Inventor Isamu Otsuka 1-1-1, Hama, Amagasaki-shi, Hyogo Co., Ltd. Kubota Corporation Inside the Technology Development Laboratory (56) References JP-A-1-290206 (JP, A) JP-A-61-166902 (JP, A) JP-A-62-74032 (JP, A) JP-A-4-99833 (JP) , A) JP-A-62-232103 (JP, A) JP-A-4-341502 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B22F 3/15 C22C 1/04 C22C 45/00

Claims (2)

(57) [Claims] An amorphous alloy powder having a softening point of an amorphous alloy
Amorphous alloy powder with an average particle size lower than the crystallization temperature of gold
With glass powder smaller than 1/20 of the average particle size of
And mixing the obtained mixed powder from the softening point of the glass.
Pressure at a temperature lower than the crystallization temperature of the amorphous alloy
Amorphous alloy powder having a step of sintering
Method for producing a bulk molded article. 2. An amorphous alloy powder and a glass powder having a softening point lower than the crystallization temperature of the amorphous alloy are mixed, and the average particle diameter of the glass powder is reduced by stirring.
Gala until it is smaller than 1/20 of the average particle size of the gold powder
And a step of sintering the obtained mixed powder under pressure at a temperature higher than the softening point of glass and lower than the crystallization temperature of the amorphous alloy. A method for producing a bulk compact of an amorphous alloy powder.