JPH0639670B2 - Method for producing manganese-aluminum-carbon alloy magnet - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a permanent magnet. More specifically, the present invention relates to a method for producing a polycrystalline manganese-aluminum-carbon system (Mn-Al-C system) alloy magnet, and particularly to a method for producing a Mn-Al-C system alloy magnet for multipolar magnetization. is there.

2. Description of the Related Art Mn-Al-C based magnet alloys are a general term for Mn-Al-C based magnet alloys and Mn-Al-C based alloy magnets. The Mn-Al-C magnet alloy is 68 to 73 mass%.
(Hereinafter simply expressed as%) Mn and (1/10 Mn-6.
6) to (1 / 3Mn-22.2)% of C and the balance of Al, and a ternary system alloy containing no additional element other than impurities and a quaternary or more multicomponent magnet alloy containing a small amount of additional element Are known and are generic terms. Similarly, M
n-Al-C alloy magnet is composed of mainly face-centered tetragonal (tau phase, L1 ₀ type ordered lattice) is a ferromagnetic phase of tissue are those containing C as essential constituent elements, in addition to impurities A ternary system magnet containing no additional element and a quaternary or more multi-component alloy magnet containing a small amount of additional element are known, and they are collectively referred to.

Further, as a method for producing this Mn-Al-C alloy magnet, a method including a warm plastic working step such as warm extrusion processing is known in addition to the method by casting and heat treatment. In particular, the latter is known as a method for producing an anisotropic magnet having excellent properties such as high magnetic properties, mechanical strength, weather resistance and machinability.

As a method for producing the Mn-Al-C alloy magnet for multipolar magnetization, an isotropic magnet, a compression processing method, and a uniaxially anisotropic polycrystalline Mn obtained by a known method such as warm extrusion processing in advance.
-Al-C alloy magnet by free warm compression in the anisotropic direction (Japanese Patent Laid-Open No. 56-119762), and a hollow billet shaft made of Mn-Al-C magnet alloy. Various plastic workings that give compressive strain in the direction (for example, JP-A-58-182208 and JP-A-58-192306) are known.

Problems to be Solved by the Invention Various types of plastic working that give compressive strain in the axial direction of the hollow billet made of the Mn-Al-C based magnet alloy described above (especially JP-A-58-182208). )
That is, that is, polycrystalline Mn-A that has been anisotropy beforehand
In a method of performing compression processing in the axial direction of the billet in a state where the outer circumference of the billet is constrained and at least a part of the inner circumference is free, in a billet having a hollow body made of an lC-based alloy magnet, for example, A hollow billet composed of a uniaxially anisotropic polycrystalline Mn-Al-C alloy magnet obtained by a known method such as extrusion is used. By subjecting the billet to the specific compression process described above, a magnet exhibiting excellent magnetic characteristics when multi-polarized is obtained. However, the above method requires at least two types of plastic working, extrusion processing and compression processing.The billet after extrusion has an easy magnetization direction in the extrusion direction, and it has excellent magnetic properties when it is magnetized in multiple poles by compression processing. A magnetic anisotropy structure is converted into a magnet exhibiting characteristics. In other words, the billet after extrusion has a uniaxial anisotropy that has a direction of easy magnetization in the axial direction of the billet, and has an anisotropic structure that is not suitable for multipolar magnetization. The magnetic properties in the circumferential direction are improved, and the magnetic anisotropy structure is converted into a magnet that exhibits excellent magnetic properties when magnetized in multiple poles.

In the method described above, the magnet is made into a uniaxial anisotropic magnet (an anisotropic magnet that is not suitable for multi-pole magnetization) by extrusion, and then a magnet that exhibits excellent magnetic properties when multi-polarized by compression. This is a wasteful manufacturing method in terms of magnetic characteristics.

The present invention aims to obtain excellent magnetic properties with a small amount of processing.

Means for Solving the Problems In order to solve the problems described above, the present invention provides a hollow billet made of a manganese-aluminum-carbon magnet alloy at a temperature of 530 to 830 ° C. and a container part. The hollow portion has a hollow cross-sectional shape, and the die is used in which the opening area of the container is larger than the opening area of the bearing, and the extrusion is performed by making the extrusion direction parallel to the axial direction of the billet. After the hollow billet is stretched in the axial direction and the circumferential direction, the billet is stretched in the axial direction while the outer circumference of the stretched billet is restrained and at least a part of the inner circumference is free. Is to be compressed.

Operation According to the method described above, that is, after performing the specific extrusion processing described above, and then performing the specific compression processing described above, after performing the known extrusion processing until now, the specific compression processing described above is performed. Even if the total plastic working amount is smaller than that of the method, a magnet exhibiting excellent magnetic characteristics can be obtained when magnetized with multiple poles.

Example The present invention is a hollow body-shaped billet made of a manganese-aluminum-carbon magnet alloy, has a hollow cross-sectional shape of the container portion at a temperature of 530 to 830 ° C., and has an opening area of the container portion. Using a die larger than the opening area of the bearing part, the extrusion process is performed by making the extrusion direction parallel to the axial direction of the billet, and after the extrusion process, the hollow billet is expanded in the axial direction and the circumferential direction. Further, the billet after extension is compressed in the axial direction of the billet after extension while the outer periphery of the billet is constrained and at least a part of the inner periphery is free.

By subjecting the above-mentioned extrusion process to Mn-Al which has been previously anisotropy by known extrusion processes.
By the method of obtaining a -C alloy magnet, a magnet exhibiting excellent magnetic characteristics can be obtained when multipolar magnetization is performed even if the amount of strain during compression processing is small.

The above-mentioned extrusion processing and compression processing do not necessarily have to be continuous plastic processing, and may be given by dividing into multiple times.

An example of the extrusion processing of the present invention described above will be described with reference to FIG. 1 in which the billet has a cylindrical shape. FIG. 1 (a) is a sectional view of a part of the die showing a state before extrusion, and similarly FIG. 1 (b) shows a state after extrusion. 1 is a billet, 2 is a mandrel, 3 is a die, and 4 and 5 are punches. The mandrel 2 and the dice 3 form a dice. In FIG. 1, 6 is a container part, which is a part for accommodating the billet 1 before extrusion, and 7
Is a bearing portion for accommodating the billet 1 after extrusion. 8 is a conical part. Also the container part 6
The opening area of is the cross-sectional area of the cavity of the container part 6 (perpendicular to the extrusion direction), and is substantially the same as the cross-sectional area of the billet 1 in FIG. 1 (a). It is the cross-sectional area of the cavity of the portion 7 (perpendicular to the extrusion direction), and is substantially the same as the cross-sectional area of the billet 1 in FIG. 1 (b).

In FIG. 1, since both the container portion 6 and the bearing portion 7 are circular with the extruding shaft as the center, in other words, the opening area of the container portion 6 is a ring shape defined by the outer diameter and the inner diameter of the container portion 6. Area. The cross-sectional shape of the hollow portion of the container portion 6 is the above-mentioned ring shape and is hollow. Similarly, the opening area of the bearing portion 7 is a ring-shaped area formed by the outer diameter and the inner diameter of the bearing portion 7. For example, the outer diameter of the container portion 6 is 40 mm, the inner diameter is 20 mm,
50mm outer diameter of the bearing portion 7, when the inner diameter and 40 mm, opening area of the container section 6 about 942 mm ^2, the opening area of the bearing part 7 is approximately 707mm ^2. The cross-sectional shape of the hollow portion of the container portion 6 is a ring shape having an outer diameter of 40 mm and an inner diameter of 20 mm. In other words, the hollow portion of the container portion 6 has a hollow cross-sectional shape when the billet 1 is housed in the container portion 6 as shown in FIG. That is, there is a die constituent member (mandrel 2) in the center, a billet 1 is further outside thereof, and a die 3 is further outside thereof.

An example of the extrusion processing method will be described with reference to FIG. First, as shown in FIG. 2 (a), a cylindrical billet 1'is housed in the container portion 6. By pressing the billet 1'using the punch 4, the state shown in FIG. 2 (b) is obtained. Next, as shown in FIG. 2 (c), a billet 1 is newly placed in the container portion 6.
2 and the billet 1 is pressed by using the punch 4 in the same manner as described above, the state shown in FIG. 2 (d) is obtained.
Thereafter, extrusion processing is performed by repeating this.

As another extrusion processing method, in the state shown in FIG. 2 (c), the billet 1 is moved in the direction from the container part 6 to the bearing part 7 while pressing the billet 1 with the punches 4 and 5 (second part). In the figure, the state of the billet 1 is shown in FIG.
There is a method of performing extrusion processing by moving from (c) to FIG. 2 (d)).

In Fig. 2 (a), the shape of the cylindrical billet has an appropriate clearance in order to make it easier to insert it into the container, but the cross section of the cylindrical billet (the surface perpendicular to the axial direction) The cross-sectional shape of the hollow portion of the container portion (the shape of the hollow portion when the die is cut along a plane perpendicular to the extrusion direction) is ring-shaped.

The compression process in the next step and the method of applying a compressive strain to a part of the billet in the axial direction of the billet are the same as those of the above-mentioned known technique (Japanese Patent Laid-Open No. 58-182208).

Regarding the temperature range in which the plastic working (extrusion processing and compression processing) as described above is possible, the working could be performed in the temperature range of 530 to 830 ° C, but at the temperature exceeding 780 ° C, the magnetic properties were considerably deteriorated. A more desirable temperature range was 560 to 760 ° C.

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

Example 1 In the composition, 69.5% Mn, 29.3% Al, 0.
5% C and 0.7% Ni are melt-cast and the outer diameter is 30 m
A cylindrical billet having an m, an inner diameter of 10 mm and a length of 20 mm was produced. After holding this billet at 1100 ° C. for 2 hours,
After air-cooling to 00 ° C., holding at 600 ° C. for 30 minutes, heat treatment of allowing to cool to room temperature was performed.

Next, extrusion processing as shown in FIG. 1 was performed at a temperature of 720 ° C. through a lubricant. In Fig. 1, the outer diameter of the container part of the die is 30 mm, the inner diameter is 10 mm, the outer diameter of the bearing part is 40 mm, the inner diameter is 35 mm, and X is 20 mm.
Is. The billet after extrusion has an outer diameter of 40 mm and an inner diameter of 35.
mm and the length was 42.7 mm. Next, this cylindrical billet was constrained to the outer peripheral surface of the cylindrical billet through a lubricant using a mold as shown in FIG. 3, and the inner periphery was made free, and at a temperature of 680 ° C. Length of cylindrical billet is 2
Compressed to 0 mm. In addition, in FIG.
FIG. 3A shows a state before processing, and FIG. 3B shows a state after processing. 1 is a billet, 4 and 5 are punches, and 9 is an outer mold. As shown in FIG. 3 (a), the billet 1 is formed by the outer mold 9.
Restrain the outer peripheral surface. By pressing the billet 1 with the punches 4 and 5, the billet 1 is axially compressed.
The inner diameter of the outer mold 9 is 40 mm.

This compression processed billet has an outer diameter of 38 mm and an inner diameter of 29
As a cylindrical magnet having a length of 20 mm and a length of 20 mm, the outer peripheral surface was magnetized with 30 poles. For the magnetization, a 2000 μF oil condenser was used and pulsed at 1500 V. The surface magnetic flux density on the outer peripheral surface was measured with a Hall element. For comparison, Mn, Al, C having the same composition as the composition described above
And Ni were melt-cast to produce a cylindrical billet having a diameter of 60 mm and a length of 20 mm. The billet was held at 1100 ° C. for 2 hours and then heat-treated by allowing it to cool to room temperature. Next, a known extrusion process up to a diameter of 40 mm was performed at a temperature of 720 ° C. through a lubricant. This extruded rod is 42.7 mm long
It was cut into pieces and cut to prepare a cylindrical billet having an outer diameter of 40 mm, an inner diameter of 35 mm and a length of 42.7 mm. Next, this billet was subjected to the same compression processing as the above-mentioned compression processing, and was further cut into a cylindrical shape in the same manner as described above, magnetized, and the surface magnetic flux density was measured.

Comparing the above two values, the value of the surface magnetic flux density of the magnet obtained by the method of the present invention was about 1.2 times that of the magnet produced for comparison.

Further, only the outer peripheral portion of the billet was compression-processed at a temperature of 680 ° C. using a mold as shown in FIG. FIG. 4 (a) shows a state before processing, and FIG. 4 (b) shows a state after processing. 10 is a fixed punch, 11 is a movable punch, and 12 is a lower die. The fixing punch 10 and the lower die 12 fix and restrain the billet, and the movable punch 11 pressurizes the billet 1 to the state shown in FIG. 4 (b), whereby only the outer peripheral portion of the billet is compressed. Is processed. The diameter of the punch 10 (the inner diameter of the punch 11) is 34 mm. The outer peripheral length after compression processing was 15 mm. The billet after processing is cut to have an outer diameter of 38 mm and magnetized in the same manner as above.
Comparing the values of the surface magnetic flux density before and after the local compression processing, the value after the processing was higher by 0.2 kG.

Example 2 69.4% of Mn, 29.3% of Al, and 0.
5% C, 0.7% Ni and 0.1% Ti were melted and cast to prepare a cylindrical billet having an outer diameter of 20 mm, an inner diameter of 5 mm and a length of 20 mm. The billet was held at 1100 ° C. for 2 hours, then air-cooled to 600 ° C., held at 600 ° C. for 30 minutes, and then heat-treated to cool to room temperature.

Next, extrusion processing as shown in FIG. 1 was performed at a temperature of 720 ° C. through a lubricant. In FIG. 1, the outer diameter of the container portion of the die is 20 mm, the inner diameter is 5 mm, the outer diameter of the bearing portion is 30 mm, the inner diameter is 26 mm, and X is 20 mm. The billet after extrusion has an outer diameter of 30 mm and an inner diameter of 26 m.
The length was 33.5 mm. Next, this cylindrical billet was constrained to the outer peripheral surface of the cylindrical billet through a lubricant using a mold as shown in FIG. 3, and the inner circumference was made free, and the cylindrical billet was heated at a temperature of 680 ° C. Length of 16mm
Was compressed. In FIG. 3, the inner diameter of the outer mold 9 is 30 mm.

The billet that has been subjected to this compression processing has an outer diameter of 29 mm and an inner diameter of 21
As a cylindrical magnet having a length of 16 mm and a length of 16 mm, the outer peripheral surface was magnetized with 18 poles. The magnetization was pulse-magnetized at 1500 V using a 2000 μF oil condenser. The surface magnetic flux density on the outer peripheral surface was measured with a Hall element. For comparison,
Mn, Al, C, N having the same composition as the composition described above
i and Ti were melted and cast to form a cylindrical billet having a diameter of 50 mm and a length of 20 mm. This billet is 2 at 1100 ℃
After holding for a time, a heat treatment of cooling to room temperature was performed. Then, a known extrusion process up to a diameter of 30 mm was performed at a temperature of 720 ° C. through a lubricant. This extruded rod has a length of 33.5
cut into mm and cut, outer diameter 30mm, inner diameter 26mm,
A cylindrical billet having a length of 33.5 mm was produced. Next, this billet was subjected to the same compression processing as the above-mentioned compression processing, and was further cut into a cylindrical shape in the same manner as described above, magnetized, and the surface magnetic flux density was measured.

Comparing the above two values, the value of the surface magnetic flux density of the magnet obtained by the method of the present invention was about 1.2 times that of the magnet produced for comparison.

Further, the magnet magnetized previously according to the present invention was compression-processed only at the outer peripheral portion at a temperature of 680 ° C. and 6 using a mold as shown in FIG. The diameter of the punch 10 (the inner diameter of the punch 11) is 24 mm. The outer peripheral length after compression processing was 10 mm. After machining, the billet was machined to have an outer diameter of 29 mm, magnetized in the same manner as above, and the surface magnetic flux density values before and after this local compression were compared.
G became higher.

Example 3 Mn, Al, C and Ni having the same blending composition as in Example 1 were melt cast to prepare a cylindrical billet having an outer diameter of 40 mm, an inner diameter of 30 mm and a length of 20 mm. The billet was held at 1100 ° C. for 2 hours, then air-cooled to 600 ° C., held at 600 ° C. for 30 minutes, and then heat-treated to cool to room temperature.

Next, extrusion processing as shown in FIG. 1 was performed at a temperature of 720 ° C. through a lubricant. In FIG. 1, the outer diameter of the container part of the die is 40 mm, the inner diameter is 30 mm, the outer diameter of the bearing part is 30 mm, the inner diameter is 20.8 mm, and X is 2
It is 0 mm. The billet after extrusion had an outer diameter of 30 mm, an inner diameter of 20.8 mm and a length of 30 mm. Next, this cylindrical billet was constrained to the outer peripheral surface of the cylindrical billet through a lubricant using a mold as shown in FIG. 3, and the inner circumference was made free, and the cylindrical billet was heated at a temperature of 680 ° C. Length of 2
Compressed to 0 mm. In FIG. 3, the inner diameter of the outer mold 9 is 30 mm.

The billet that has been subjected to this compression processing has an outer diameter of 29 mm and an inner diameter of 18
As a cylindrical magnet having a length of 20 mm and a length of 20 mm, 12 poles were radially magnetized from the outer peripheral surface and the inner peripheral surface as shown in FIG. FIG. 5 schematically shows the formation of a magnetic path (indicated by a broken line in the drawing) inside the magnet when the magnet is multi-polarized in the radial direction. As shown in FIG. 5, the magnetic path is substantially along the radial direction of the magnet. The magnetization was pulse-magnetized at 1500 V using a 2000 μF oil condenser.
The surface magnetic flux density on the outer peripheral surface was measured with a Hall element. For comparison, Mn and A having the same composition as the composition described above are used.
l, C and Ni are melt-cast, diameter 60mm, length 20mm
The cylindrical billet of was produced. This billet is 1100 ℃
After being held for 2 hours at room temperature, a heat treatment of allowing to cool to room temperature was performed. Then, through the lubricant, at a temperature of 720 ° C., a diameter of 40
Known extrusion processes up to mm were performed. This extruded rod has a length of 3
Cut to 0mm and cut to have an outer diameter of 30mm and an inner diameter of 20.
A cylindrical billet having a length of 8 mm and a length of 30 mm was produced. Next, this billet was subjected to the same compression processing as the above-mentioned compression processing, and was further cut into a cylindrical shape in the same manner as described above, magnetized, and the surface magnetic flux density was measured.

Comparing the above two values, the value of the surface magnetic flux density of the magnet obtained by the method of the present invention was about 1.2 times that of the magnet produced for comparison.

Further, only the outer peripheral portion of the billet was compression-processed at a temperature of 680 ° C. by using a magnet as previously magnetized of the present invention using a mold as shown in FIG. The diameter of punch 10 (punch 1
The inner diameter of 1) is 24 mm. The outer peripheral length after compression processing was 15 mm. After machining, the billet was machined to have an outer diameter of 29 mm, directly magnetized in the same manner as above, and the surface magnetic flux density values were compared before and after this local compression processing. It became high.

Example 4 Mn, Al, C and Ni having the same composition as in Example 1 were melt-cast and a cylindrical billet having a diameter of 50 mm and a length of 20 mm was produced. The billet was held at 1100 ° C. for 2 hours and then heat-treated by allowing it to cool to room temperature.

Then, a known extrusion process up to a diameter of 30 mm was performed at a temperature of 720 ° C. through a lubricant. The extruded rod is cut to a length of 20 mm and cut to an outer diameter of 30 mm, an inner diameter of 10 mm, and a length of 2.
A 0 mm cylindrical billet (billet A) was used. In addition, the extruded rod is cut into a length of 20 mm and cut to have a diameter of 29 mm,
A cylindrical billet having a length of 40 mm (billet B) was used. The billet B was subjected to free compression processing in the axial direction of the billet at a temperature of 660 ° C via a lubricant. The length of the billet after processing was 20 mm. The billet (plane anisotropic magnet) after this processing is cut like the billet A to have an outer diameter of 30 m.
A cylindrical billet (billet B) having an m, an inner diameter of 10 mm and a length of 20 mm was used. Next, as in Example 1, the billet A and the billet B were extruded through a lubricant at a temperature of 720 ° C. using a die as shown in FIG. In FIG. 1, the outer diameter of the container portion of the die is 30 mm, the inner diameter is 10 mm, the outer diameter of the bearing portion is 40 mm, the inner diameter is 35 mm, and X is 20 mm. The billet after extrusion had an outer diameter of 40 mm, an inner diameter of 35 mm and a length of 42.7 mm. Next, these cylindrical billets are passed through a lubricant to a third
Using the mold shown in the figure, the outer peripheral surface of the cylindrical billet was constrained, and the inner periphery was made free, and the cylindrical billet was compressed to a length of 20 mm at a temperature of 680 ° C. In FIG. 3, the inner diameter of the outer mold 9 is 40 mm.

Billets that have been subjected to this compression process have an outer diameter of 38 mm,
As a cylindrical magnet having an inner diameter of 29 mm and a length of 20 mm, the outer peripheral surface was magnetized with 30 poles. The magnetization was pulse-magnetized at 1500 V using a 2000 μF oil condenser. The surface magnetic flux density on the outer peripheral surface was measured with a Hall element, and
Compared with the magnet obtained in.

Comparing the above values (the magnet of the present invention using billet A and billet B and the magnet obtained in Example 1), the value of the surface magnetic flux density of the magnet obtained in Example 4 is About 1.2 for the magnet using the billet A of the manufactured magnet
And the magnet using the billet B was about 1.3 times.

Further, the magnet magnetized previously according to the present invention was subjected to compression processing only at the outer peripheral portion of the billet at a temperature of 680 ° C. using a mold as shown in FIG. The diameter of the punch 10 (the inner diameter of the punch 11) is 34 mm. The outer peripheral length after compression processing was 15 mm. After machining the billet after processing, magnetizing it with an outer diameter of 38 mm and magnetizing it in the same manner as above, and comparing the values of the surface magnetic flux density before and after this local compression processing, respectively It increased by 0.2 kG.

As described above, regarding the composition of the Mn-Al-C based magnet alloy, N
Only the i-added quaternary system and the Ni- and Ti-added quinary system are shown, but the ternary system, which is the basic composition of the Mn-Al-C alloy magnet, is also plastically worked (extrusion + compression). Although a slight difference was found in the magnetic properties of the subsequent magnets, the improvement in the magnetic properties as described above was recognized by the known extrusion method.

As for the local compression processing, only the method of compressing only the outer peripheral portion of the billet is shown, but even when only the inner peripheral portion of the billet is compressed, the improvement of the magnetic characteristics is similarly recognized.

EFFECTS OF THE INVENTION As described in the examples, according to the present invention, a hollow body-shaped billet made of a manganese-aluminum-carbon magnet alloy has a hollow cross-sectional shape of a hollow portion of a container portion at a temperature of 530 to 830 ° C. And, using a die in which the opening area of the container part is larger than the opening area of the bearing part, extrusion processing is performed by making the extrusion direction parallel to the axial direction of the billet,
By this extrusion, the hollow billet is stretched in the axial direction and the circumferential direction, and then the outer circumference of the stretched billet is constrained and at least a part of the inner circumference is free, A magnet exhibiting high magnetic characteristics when subjected to multipole magnetization by subjecting the billet to compression processing in the axial direction.

By this method, that is, after performing the specific extrusion processing described above, by performing the specific compression processing described above, after performing the publicly known extrusion processing until now, a total of more than the method performing the specific compression processing described above. A magnet exhibiting excellent magnetic characteristics can be obtained when magnetized in multiple poles, even if the plastic working amount is small.

[Brief description of drawings]

1A and 1B are partial sectional views of a mold showing an example of extrusion processing of the present invention, and FIGS. 2A to 2D are partial sectional views of a mold showing an example of extrusion method of the present invention, 3a, b and 4a,
FIG. 5b is a partial cross-sectional view of a mold showing an example of compression processing of the present invention, and FIG. 5 is a schematic view of forming a magnetic path inside the magnet when multi-pole magnetizing is performed in the radial direction of the cylindrical magnet. FIG. 1, 1 '... Billet, 2 ... Mandrel, 3 ... Die, 4, 5 ... Punch, 6 ... Container part, 7 ... Bearing part, 8 ... Conical part, 9 ... Outer mold, 10 ... fixed punch, 11 ... movable punch, 12 ... lower mold.

Claims (2)

[Claims] 1. A hollow body-shaped billet made of a manganese-aluminum-carbon magnet alloy, having a hollow cross-sectional shape of a hollow portion of a container portion at a temperature of 530 to 830 ° C.,
Using a die whose opening area of the container part is larger than that of the bearing part, the billet is extruded with the axial direction parallel to the extruding direction, and the hollow billet is extruded by the extruding process. After being stretched, the manganese is characterized in that the billet after stretching is constrained at its outer periphery and at least a part of its inner periphery is free, and then compression processing is applied in the axial direction of the billet after stretching. -Aluminum-Carbon-based alloy magnet manufacturing method. 2. A hollow body-shaped billet made of a manganese-aluminum-carbon magnet alloy, having a hollow cross section at a temperature of 530 to 830 ° C.
Using a die whose opening area of the container part is larger than that of the bearing part, the billet is extruded with the axial direction parallel to the extruding direction, and the hollow billet is extruded by the extruding process. After stretching the billet, the billet after the stretching is constrained, and at least a part of the inner circumference is free, and then the billet is compressed in the axial direction, and then a part of the billet after the compression. A method for producing a manganese-aluminum-carbon alloy magnet, comprising subjecting a billet to axial compression processing.