JPH0434805B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method of manufacturing a permanent magnet. More specifically, the present invention relates to a method of manufacturing a polycrystalline manganese-aluminum-carbon (Mn-Al-C) alloy magnet, and particularly to a method of manufacturing a Mn-Al-C alloy magnet for multipolar magnetization.

Structure of conventional example and its problems Mn-Al-C alloy for magnet is 68 to 73% by weight
(hereinafter expressed simply as %) and (1/10M−6.6) ~
Multi-component magnet alloys are known, consisting of (1/3Mn-22.2)% C and the balance Al, including ternary alloys containing no additive elements other than impurities, and quaternary or higher alloys containing small amounts of additive elements. , is a general term for these. Similarly, Mn-Al-C alloy magnets are mainly composed of a face-centered tetragonal (τ phase, L1 ₀ type regular lattice) structure, which is a ferromagnetic phase, and contain C as an essential constituent element, and do not contain impurities. Multi-component alloy magnets are known, including ternary alloy magnets containing no additional elements and quaternary or higher alloy magnets containing a small amount of additive elements.

The Mn-Al-C magnetic alloy is the Mn-Al
It is a general term for -C alloy for magnets and Mn-Al-C alloy magnet. In particular, in the present invention, as detailed in the Examples, the former refers to those that have undergone melting and casting and heat treatment, and the latter refers to those that have undergone some kind of plastic working after that.

In addition, known methods for producing Mn--Al--C alloy magnets include, in addition to casting and heat treatment, a plastic working process such as extrusion.
In particular, the latter method is known as a method for producing anisotropic magnets having excellent properties such as high magnetic properties, mechanical strength, weather resistance, and machinability.

Manufacturing methods for Mn-Al-C alloy magnets for multipolar magnetization include isotropic magnets, compression processing, and uniaxially anisotropic polycrystalline Mn obtained in advance by known methods such as extrusion processing. -Al-C alloy magnets subjected to free compression processing in an anisotropic direction (composite processing method) are known.

Compression processing provides high magnetic properties in the radial direction, but a relatively large processing rate is required, non-uniform deformation may occur, and the presence of undeformed bands is unavoidable. There are problems such as: With the combined processing method, high magnetic properties are obtained in all directions within the plane, including the radial and chordal directions, with small compressive strain. The magnet obtained by the composite processing method has an easy magnetization direction parallel to a specific plane, is magnetically isotropic within the plane, and includes a line perpendicular to the plane and a straight line parallel to the plane. It has a structure that is anisotropic in a plane (hereinafter, such a magnet will be referred to as a plane anisotropic magnet).

On the other hand, the shape of a magnet used in the field of multipolar magnetization is generally an axially symmetrical shape, and an example is a cylindrical shape. FIG. 1 schematically shows the formation of a magnetic path inside a cylindrical magnet when the inner periphery of the magnet is multipole magnetized. In Fig. 1, the broken line indicates the magnetic path, and the chordal direction (θ
direction). Radial direction of cylinder (r direction)
The direction perpendicular to the axial direction of the cylinder and the axial direction of the cylinder is defined as the chordal direction (θ direction).

As shown in FIG. 1, the magnetic path runs approximately in the radial direction at the inner circumferential portion, along the chord direction at the outer portion, and no magnetic path runs at the outer portion. If the shape of the magnet is cylindrical, the magnet can be divided into three parts as mentioned above.
The first is the part where the magnetic path runs along the radial direction (part A),
The second is the part where the magnetic path is along the chord direction (part B),
The third part is a part (C part) through which no magnetic path passes.

The above-mentioned plane anisotropic magnet has an easy magnetization direction in any direction parallel to the plane including the radial direction and the chordal direction, so it has excellent magnetic properties when magnetized on the inner circumference in this way. However, when it is divided into three parts as described above, each part does not have a desirable anisotropic structure. That is, it is better for the A part to have higher magnetic properties in the radial direction than in the chordal direction, and it is better for the B part to have higher magnetic properties in the chordal direction than in the radial direction. On the other hand, if a radially anisotropic magnet (or a magnet with a radial direction of easy magnetization) is shaped like a hollow body, it is easy to magnetize parallel to a straight line passing through any point on a plane perpendicular to the axial direction of the hollow body. In the case of a cylindrical magnet shown in Fig. 1, which has an easy magnetization direction in the r direction (radial direction), it has a desirable anisotropic structure in the A part, but it is conversely desirable in the B part. It has no anisotropic structure.

Purpose of the Invention The present invention provides an Mn-Al material suitable for high-performance multipole magnetization.
- It is an object of the present invention to provide a method for manufacturing a C-based alloy magnet.

Composition of the Invention The present invention provides a 530 mm hollow billet made of a Mn-Al-C based magnet alloy in a hollow portion of a hollow billet made of a metal material.
The method is characterized in that the two billets are compressed in the axial direction of the hollow billet made of the Mn-Al-C magnet alloy at a temperature of ~830°C until the two billets come into contact with each other or further until they are integrated. .

By compressing the Mn-Al-C alloy for magnets, with a hollow billet made of a metal material on the outside, until the two billets come into contact with each other or further. , Mn-Al-C with radial easy magnetization direction
By compressing it together with a hollow billet made of metal material, compression processing becomes effective (refining the structure, making it anisotropic, improving magnetic properties, etc.) Provided for Mn-Al-C alloys for magnets.

Furthermore, if the hollow billet made of the metal material is a hollow billet with at least the inner periphery made of a magnetic material, it is possible to obtain a magnet having two structures suitable for inner periphery magnetization as described above. can.

After compression processing, a hollow billet made of Mn-Al-C alloy for magnets becomes a magnet with a structure suitable for part A, and after compression processing, the magnetic material part becomes a part with a structure suitable for part B. . Moreover, since the two billets are compressed at the same time and brought into contact with each other, it is possible to obtain a magnet having two or more types of structures after the compression process.

Description of Examples In a state where a hollow billet made of an Mn-Al-C alloy for magnets is present in the hollow part of the hollow billet made of a metal material, the Mn-Al-
A Mn-Al-C alloy magnet having a radial direction of easy magnetization is produced by compressing a hollow billet made of a C-based magnet alloy until the two billets come into contact with each other in the axial direction or further. Since compression processing is performed together with a hollow billet made of metal material, the effects of compression processing (microstructural refinement, anisotropy, improvement of magnetic properties, etc.) can be efficiently applied to Mn-Al. -Given to C-based magnet alloys.

The metal material mentioned above may be any material that can be compressed together with the Mn-Al-C alloy for magnets in the temperature range of 530 to 830°C. There is no need to be particular about metal materials in general. In other words, any billet made of a certain material is sufficient. However, in general, for example,
Examples include steel, brass, copper, etc., and in some cases, it may not be limited to bulk materials but may also be powder materials.

Further, if the hollow billet made of the metal material described above is made of a magnetic material at least in its inner circumference, the inner circumference of the billet after compression processing (before compression processing is Mn-Al-C based). The part (corresponding to the hollow billet made of the magnet alloy) has high magnetic properties in the radial direction, and the part outside of it (the part corresponding to the magnetic material) has a magnetic path when internal magnetization is applied. This is the part suitable for following the string direction. As a result, three divided portions A and B are formed when the inner circumferential magnetization described above is applied, and a magnet exhibiting excellent magnetic properties when inner circumference magnetized is obtained.

The above-mentioned magnetic material may be any magnetic material as long as the chord direction does not become the difficult-to-magnetize direction after the above-described compression process. Here, the difficult magnetization direction means the direction in which magnetization is difficult in outer circumferential magnetization, such as the [111] direction of single crystal Fe.
= 500 Oe, if there is no significant difference in magnetization strength from the [100] direction of the easy axis of magnetization, it cannot be said that it is a difficult direction for magnetization in outer circumference magnetization. Examples of the magnetic material include Mn-Al-C magnetic alloy, isotropic Mn
-Al-C alloy magnet, pure iron, electromagnetic soft iron, Fe-Co
Examples include high permeability materials such as alloys.

The compression process described above does not necessarily have to be continuous compression process, and may be divided into multiple times. Furthermore, the billet which has been subjected to the above-mentioned compression processing may be further subjected to compression processing in the axial direction on a portion (for example, the inner peripheral portion) of the billet.

As an example of the above-mentioned compression processing, two hollow body-like billets are both made into cylindrical shapes, and the cylindrical billets made of metal material are made into billet A1, Mn-Al.
A cylindrical billet made of a -C alloy for magnets is shown as billet B2 in FIGS. 2 to 6. In each figure, (a) shows the state before compression processing, and (b) schematically shows the state after compression processing. In FIGS. 2 to 6, 1 is billet A and 2 is billet B. 3 is a billet (billet C) made of a metal material other than billet A. 4 and 5 are punches, which can be moved freely in the axial direction and can also be fixed at a certain position. 6 is the outer mold.

First, in the example shown in FIG. 2, with the outer periphery of billet A restrained, billet B is placed in contact with billet A as shown in (a), and compression processing is performed. By subjecting both billets A and B to compression processing, billet B has both an outer diameter and an inner diameter smaller after compression processing than before processing. As in the example shown in Fig. 2, billets 1 and 2 are both one cylindrical billet made of Mn-Al-C alloy for magnets. When both are subjected to compression processing, the compression processing is effectively applied to the Mn-Al-C alloy for magnets, as described above.

In the example of FIG. 3, unlike the case of FIG. 2, there is a considerable gap between billets A and B. After compression processing, as shown in (b), it is almost the same as the case in FIG. 2.

The example shown in FIG. 4 differs from the case shown in FIG. 2 in that the outer periphery of the billet A is not in contact with the outer mold 6. In other words, the outer periphery of billet A is not constrained before compression processing. As the compression process progresses, the system of both billets becomes larger, and eventually the outer periphery of billet A comes into contact with the outer mold, and thereafter the same deformation as shown in FIG. 2 takes place.

In the example of FIG. 5, billet C3 is present in the center of the case of FIG. 2. Compression processing can be performed until the space within the mold (the space surrounded by the punches 4 and 5 and the outer mold 6) is almost filled with billet. Before compression processing, if the temperature in the area shown in the figure (especially the space where the billet exists and its vicinity) is approximately the same, the inner circumferential surface of the billet will actually be a curved surface, and the central part (height direction, axis Although the inner diameter of the center portion (with respect to the direction) is the smallest, by inserting the billet C and compressing it together, the curvature of the curved surface (change in the inner diameter) can be reduced. Instead of using the billet C illustrated in FIG. 5, a mandrel or the like may be used for the purpose of forming the inner peripheral surface. Further, a mandrel or the like may be used not only in FIG. 5 but also in all the examples shown in FIGS. 2 to 6 for the purpose of forming the inner circumferential surface.

In the example of FIG. 6, the pillar C in FIG. 5 has a cylindrical shape.

In the above example, the outer periphery of the billet B in FIG. 2 is restrained by the outer mold 6 via the billet A, but the inner periphery can be considered to be in a free state. On the other hand, although the outer periphery of billet B in FIG. 4 is in contact with billet A, the outer periphery of billet A is not in contact with outer mold 6 and can therefore be considered to be in a free state.

Compression processing is performed in a temperature range of 530 to 830°C, so if billets A, B, and C are made of different materials, if they are cooled to room temperature after processing, they may become a frozen spring state due to the difference in coefficient of thermal expansion, or vice versa. There may be gaps between the billets. When using a material other than the Mn-Al-C magnet alloy, it is necessary to consider the magnitude relationship with the coefficient of thermal expansion of the Mn-Al-C magnet alloy.

In the examples shown in FIGS. 2 to 6, there is a portion in the compression process in which at least the outer periphery of the pillar B is restrained. However, it is not necessarily necessary to have a portion where the compression process is performed while the outer periphery of the billet B is restrained. For example, in the processing shown in FIG. 4, the outer mold 6 may not exist. Even in this case, Mn-Al-C
By processing the billet made of an alloy for magnets while covering the outside with a billet made of a metal material, the effect of the compression process mentioned above can be efficiently achieved.
Provided for Mn-Al-C alloys for magnets. However, the effect is greater if the billet B has a portion where the compression process is performed while the outer periphery of the billet B is constrained, and the more such portions there are.

Further, in the above example, the billets A and B are made of one cylindrical body, but this is not necessarily necessary. For example, billet A or billet B in FIG. 2 may be composed of two or more parts forming a cylindrical body. In extreme cases, the portion occupied by billet A in FIG. 2 may be powder.

In the examples of FIGS. 2 to 6, the heights of billets A and B (or even billet C) before compression are approximately equal, but the heights of each billet may be different. For example, in FIG. 3, billet A may be higher than billet B.

In addition, in the above example, billet B (Mn-Al-C
Hollow body-shaped billet made of alloy magnet for system magnets)
Although we have shown an example in which compression is applied to the entire area, the structure before processing may be preserved by creating a region where compression is not applied locally. For example, in Fig. 2, the end face of the punch 5 is not flat, but has a stepped shape that matches the inner diameter of the billet B2, and a part of the inner circumference is locally restrained to create an area that will not be compressed. How to make money, etc.

Further, as described above, if it is desired to obtain a substantially cylindrical billet after compression processing, a mandrel or the like may be used for the purpose of shaping the inner peripheral surface.

Furthermore, if the cylindrical billet (billet A1) made of the metal material described above is a billet whose inner peripheral portion is made of a magnetic material, the billet B can be compressed to radially change the direction of easy magnetization. It becomes a receiving magnet, and becomes a part suitable for the part A in the above-mentioned inner circumferential magnetization. The magnetic part is B
It is possible to obtain a magnet having two or more types of structures depending on the part suitable for the part. For example, in FIG. 2, billet A1 is made of a high magnetic permeability material and billet B2 is made of a Mn--Al--C alloy for magnets.

Regarding the possible temperature range of compression processing as mentioned above, it was possible to perform it in the temperature range of 530 to 830℃, but
At temperatures above 780°C, the magnetic properties deteriorated considerably. A more desirable temperature range was 560 to 760°C.

Next, more specific embodiments of the present invention will be described.

Example 1 A mixture of 69.4% Mn, 29.3% Al, 0.5% C, 0.7% Ni and 0.1% Ti was melted and cast, and the outer diameter
Cylindrical billet (Billet B) of 35.mm, inner diameter 29.1mm, length 20mm and outer diameter 40mm, inner diameter 29.1mm, length 20
A cylindrical billet (billet D) with a diameter of 2 mm was prepared.
After holding these billets at 1100℃ for 2 hours,
After air cooling to 600℃ and holding at 600℃ for 30 minutes,
Heat treatment was performed by allowing the sample to cool to room temperature.

Next, we cut a brass bar material to create a shape with an outer diameter of 40 mm and an inner diameter of 40 mm.
Cylindrical billet 35.3mm, length 20mm (billet A)
was created. Through the above steps, a Mn-Al-C alloy for magnets is obtained.

Billet B is placed in the hollow part of billet A, set in the state shown in Figure 2, and heated to 680°C using lubricant using a mold as shown in Figure 2.
Compression processing was performed up to 10 mm in length at a temperature of . Note that the outer mold 6 of the mold used is 40 mm.

A cubic sample with a side of about 4 mm was cut out from the inner periphery of the billet after processing (corresponding to billet B before processing), with each side along the radial, chordal, and axial directions, and the magnetic properties were measured. .

The magnetic properties are Br = 5.2kG in the radial direction, Hc =
2.9k0e, (BH) _nax =4.7MG・0e, Br= in the string direction
3.0kG, Hc = 2.1k0e, (BH) _nax = 1.6MG・0e, in the axial direction Br = 3.3kG, Hc = 2.3k0e, (BH) _nax =
It was 2.0MG・0e.

Further detailed examination revealed that the inner circumference had high uniformity in terms of magnetic properties and was also uniform in terms of metallographic structure.

For comparison, billet D was compressed in the same manner as above. A cubic sample of 4 mm on a side was cut out from the outer periphery of the processed billet in the same manner as described above, and its magnetic properties were measured. The magnetic properties are Br in the radial direction.
=5.0kG, Hc=2.4k0e, (BH) _nax =3.5MG・0e,
In the string direction, Br = 3.1kG, Hc = 1.7k0e, (BH) _nax =
1.5MG・0e, Br=2.8kG in the axial direction, Hc=
1.8k0e, (BH) _nax = 1.4MG・0e. Furthermore, detailed examination in the same manner as above revealed that the uniformity of the magnetic properties was worse than that obtained by the method of the present invention, and the metallographic structure was also non-uniform.

As described above, the method according to the present invention can provide a material with higher magnetic properties in the radial direction, and moreover, a material with higher uniformity in terms of magnetic properties and metallographic structure.

Example 2 A mixture of 69.4% Mn, 29.3% Al, 0.5% C, 0.7% Ni and 0.1% Ti was melted and cast, and the outer diameter
Several cylindrical billets (billet B) with a diameter of 35 mm, an inner diameter of 29 mm, and a length of 20 mm were prepared. These billets were subjected to the same heat treatment as in Example 1.

Next, we cut a pure iron bar to create a material with an outer diameter of 40 mm and an inner diameter of 40 mm.
Several cylindrical billets (billet A) each having a length of 35 mm and a length of 20 mm were prepared.

Billet B was placed in the hollow part of billet A, and using the same mold as in Example 1, the billet B was set in the state shown in Fig. 2 and molded using lubricant at a temperature of 680°C to a length of up to 10 mm. Compression processing was performed.

After processing, the billet was cut to an outer diameter of 39 mm and an inner diameter of 22 mm. Multipole magnetization with 12 poles was applied to the inner circumference of the magnet. Magnetization was performed using a 2000 μF oil capacitor and pulsed magnetization at 2000 V. The surface magnetic flux density on the inner circumference was measured using a Hall element. The surface magnetic flux density is
It was 2.9kG.

In this way, by using pure iron (magnetic material) for billet A, the magnet after compression processing is suitable for extremely high-performance inner periphery magnetization.

Example 3 A mixture of 71.4% Mn, 26.8% Al, 1% C, 0.7% Ni and 0.1% Ti was melted and cast, and the outer diameter
A cylindrical billet (billet A) with a diameter of 34 mm, an inner diameter of 28 mm, and a length of 20 mm was prepared. This billet was heated to 1150℃ for 2 hours.
After holding for a period of time, the average cooling rate is 20℃/ to 700℃.
Heat treatment was carried out by cooling for 30 minutes and holding at 700°C for 30 minutes.

A cylinder with a compound composition of 69.4% Mn, 29.3% Al, 0.4% C, 0.7% Ni, 0.1% Ti, and 0.1% P is melted and cast, and has an outer diameter of 28 mm, an inner diameter of 19.6 mm, and a length of 20 mm. A billet (billet B) was prepared. This billet was subjected to the same heat treatment as in Example 1.

Insert billet B into the hollow part of billet A,
Using the same mold as in Example 1, the mold was set in the state shown in FIG. 4 and compressed to a length of 10 mm.

The billet after processing was cut to an outer diameter of 39 mm and an inner diameter of 22 mm, and the inner circumference was magnetized with 8 poles in the same manner as in Example 2. The surface magnetic flux density was 2.7kG. It was a magnet suitable for extremely high-performance inner circumferential magnetization.

Although the above embodiment is a typical example of the examples shown in FIGS. 2 to 6, the lengths of billet A1 and billet B2 before compression processing may be different. Furthermore, instead of compressing the entire billet, a method may be used in which the structure before processing is preserved without deforming a portion of the billet. In some cases, the billet may be formed of two or more billets to form a hollow shape. Furthermore, a mandrel or the like may be used for the purpose of shaping the inner peripheral surface.

Effects of the Invention As described above, according to the present invention, it is possible to obtain a magnet that exhibits excellent magnetic properties in multipolar magnetization. In addition, in the method of the present invention, since the Mn-Al-C alloy for magnets is compressed together with the billet made of metal material, the compression process effectively
Applied to alloys for magnets.

[Brief explanation of drawings]

Figure 1 is a diagram schematically showing the formation of a magnetic path inside the magnet when the inner circumference of a cylindrical magnet is subjected to multipolar magnetization, Figures 2, 3, 4, and 5 and FIG. 6 is a cross-sectional view of a part of a mold schematically showing an example of compression processing of the present invention. 1... Billet A, 2... Billet B, 3...
Billet C, 4, 5... Punch, 6... External mold.

Claims (1)

[Scope of Claims] 1. A hollow billet made of a manganese-aluminum-carbon alloy for magnets is inserted into the hollow part of a hollow billet made of a metal material different from the alloy for magnets, and two billets
Manganese-aluminum, characterized in that the two billets are compressed in the axial direction of the hollow billet made of the magnet alloy at a temperature of 530 to 830° C. until the two billets touch each other or further until they are integrated. Manufacturing method for carbon-based alloy magnets. 2. The method for producing a manganese-aluminum-carbon alloy magnet according to claim 1, wherein the hollow billet made of a metal material has at least an inner peripheral portion made of a magnetic material. 3. The method for manufacturing a manganese-aluminum-carbon alloy magnet according to claim 1 or 2, wherein the hollow body is cylindrical. 4. Claims 1 or 2, wherein the compression process is performed with the outer periphery of a hollow billet made of a magnet alloy being constrained, and at least a portion of the inner periphery being free. A method for manufacturing the manganese-aluminum-carbon alloy magnet described above. 5. After the compression process is performed with at least a portion of the outer periphery and inner periphery of a hollow billet made of a magnetic alloy free, the billet is further compressed with the outer periphery constrained and at least a portion of the inner periphery. Manganese according to claim 1 or 2, which is processed in a state where the manganese is free.
A method for producing an aluminum-carbon alloy magnet.