JP2003217959A - METHOD OF MANUFACTURING MnAlC MAGNET - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of the MnAlC magnet, to realize the magnetic characteristic which is similar to that of the conventional manufacturing method, introducing the capsulated powder sealing/extruding method in the MnAlC- system alloy magnet, in which the magnetic characteristics are improved with the extruding method. <P>SOLUTION: In the method of manufacturing the MnAlC-system alloy magnet, the powder of MnAlC-system alloy is sintered for 1 to 10 hrs at 1,323 to 1,473K and thereafter the sintered powder is molded at the warm extruding temperature in the range of 933 to 1,023K. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a MnAlC-based alloy magnet. [0002] Conventionally, Mn-Al-C alloy magnets are mainly composed of a face-centered tetragonal crystal structure, which is a ferromagnetic phase, and contain C as an essential constituent element. There are known three-element magnets containing no additional elements and multi-element alloy magnets of four or more elements containing a small number of additional elements, and these are generic names. In addition, rare earth metal elements and Co
It does not include rare elements such as This magnet is mainly used as a so-called anisotropic magnet having axial or radial anisotropy. This magnet is a permanent magnet that has a specific gravity of 5.1 g / cm ³ , about 70% lighter than ordinary metal magnets of the same volume, has weather resistance that does not rust in the atmosphere, and has high mechanical strength. is there. [0003] In the past, this magnet was manufactured by casting an ingot and subjected to a solution treatment at about 1000 ° C.
The material is anisotropic by hot extrusion at 0 ° C. to exhibit desired magnetic properties. Further, as a method of improving this casting method, a manufacturing method by a powder method is also being implemented. This powder method is a method that does not require the production of an ingot by a casting method and subsequent solution treatment.After melting a molten alloy having the target structure in a vacuum melting furnace, the powder method is called inert gas such as argon gas or nitrogen gas. A powder having an average particle size of 1 mm or less is produced by a gas atomizing method using a gas,
A metal container is filled with powder, heated to around 700 ° C., and extruded at a desired strain rate to form a rod-like shape. The extruded rod-shaped surface is provided by removing the container material used at the time of powder filling by centerless processing, cutting and processing into a desired length and shape. On the other hand, polycrystalline anisotropic MnA prepared by a powder method
For example, Japanese Patent Application Laid-Open No.
As disclosed in Japanese Patent No. 9305, a method in which a powder of a MnAlC-based alloy is filled into a thin plastic container, formed by cold isostatic pressing, and further subjected to warm plastic working in a temperature range of 530 to 780 ° C. Has been proposed. This is because quenching process is performed at the time of powder production such as atomization,
The heat treatment required in the case of the casting-extrusion method can be omitted, and a magnet having high magnetic properties can be manufactured even at the same extrusion ratio as compared with the casting-extrusion method. [0005] However, in order to extrude the above-mentioned powder, a capsule which is dimensioned for the extrusion is required each time. In addition, since capsules are consumables, there is a problem that manufacturing costs increase. Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have made intensive developments, and as a result, in a MnAlC-based alloy magnet whose magnetic properties are improved by an extrusion method, a conventional method has been proposed. It is intended to provide a production method for producing magnetic properties equivalent to the production method by the powder encapsulation-extrusion method at a lower cost. The gist of the invention is that in a method of manufacturing a MnAlC-based alloy magnet, a powder made of the MnAlC-based alloy is sintered at a sintering temperature of 1323 to 1473 K for a sintering time of 1 to 10 hours, and then an extrusion temperature of 933 is used. A method for producing a MnAlC magnet, wherein the magnet is formed by warm extrusion under the conditions of な る 1023 K. Hereinafter, the present invention will be described in detail. As a means for producing powder as a material in the present invention, water or gas atomization method is generally used and any of them can be used, but an inert gas atomization method is used.
It is advantageous because it becomes a spherical powder, there is no surface oxidation, and the productivity is high. The component composition of the MnAlC-based alloy magnet according to the present invention is not particularly limited. Is M
n: 68 to 73 mass%, C: 0.2 to 2.1 mas
A Mn-Al-C-based magnet containing s% and the balance being Al is preferred. In the present invention, the MnAlC-based alloy powder produced by the above-mentioned atomizing method is sintered by a mold or the like, and the powder is extruded. Therefore, a capsule for molding is not required. In addition, compared with capsules, a mold for sintering is excellent in that a plurality of molds can be formed with one mold and processing according to the extrusion size is easy. Moreover, since it can be used repeatedly, mass productivity is good and productivity can be greatly increased. According to the present invention, the sintering temperature is set to 1323 to 147.
The reason why the temperature is set to 3K is that if the temperature is lower than 1323K, sintering does not proceed sufficiently and handling is difficult, and if the temperature is higher than 1473K, precipitation of a nonmagnetic phase increases and sufficient magnetic properties cannot be secured. Therefore, more preferably 1373
１４1450K. Further, the sintering time is 1 to 10 hours.
The reason is that if it is less than 1 hr, sintering does not proceed sufficiently and handling is difficult, and if it exceeds 10 hr, precipitation of non-magnetic phase increases and sufficient magnetic properties cannot be secured.
Therefore, it is more preferably 3 to 7 hours. further,
The reason why the warm extrusion temperature was set to 933 to 1023K was that the optimum temperature for extruding the sintered sample was examined.
If the temperature is lower than 33K, the deformation resistance is large and sound extrusion is difficult. If the temperature is higher than 1023K, the precipitation of the non-magnetic phase is large and leads to the deterioration of the magnetic properties. Hereinafter, the present invention will be described specifically with reference to examples. Mn: 6 by argon gas atomization
8.8 mass%, C: 0.44 mass%, Ni:
After producing a MnAlC-based alloy powder having a composition of 0.8 mass% and a balance of Al, the powder was classified to −1000 μm to obtain a powder. This powder was sintered in an argon gas atmosphere at a sintering temperature of 132.
Sintering is carried out at 3-1473 K for a sintering time of 1 to 10 hr to obtain a sintered body having a size of 14 mm × 20 mm, and the sintered body is extruded under conditions of an extrusion temperature of 933 to 1023 K at an inlet side diameter of 15 mm and an outlet side diameter of 7 mm. , Strain rate 0.05 / s
For warm extrusion. Thereafter, a centerless processing of φ7 × L50 mm to φ5 × L10 mm and emery cutting were performed to obtain a product. Table 1 shows the results. The evaluation items were the handling properties of the sintered body and the magnetic properties of the extruded material (B
Hmax / kJ / m ³ ). The magnetic properties were evaluated using a BH tracer, and the applied magnetic field was 1.5T. Regarding the handling property of the sintered body, there was no problem in handling: ○, and handling was impossible: ×. [Table 1] As shown in Table 1, as shown in FIG. Nos. 1 to 9 are the present invention. 10 to 16 are comparative examples. Comparative Example N
o. In No. 10, since the sintering temperature is low, sufficient sintering does not proceed, and therefore, the handling of the sintered body is impossible.
On the other hand, in Comparative Example No. No. 11 cannot obtain sufficiently high magnetic properties because of the high sintering temperature. In Comparative Example No. 12
No. 2 has a long sintering time. As in the case of No. 11, sufficient magnetic properties cannot be obtained. In Comparative Example No. In No. 13, the sintering time is short, so that the sintered body cannot be handled easily. In Comparative Example No. No. 14 cannot be extruded because the extrusion temperature is low. In Comparative Example No. Fifteen
Cannot obtain sufficiently high magnetic properties because of high extrusion temperature. Further, in Comparative Example No. No. 16 is obtained by encapsulation without sintering, and has a problem in that high magnetic properties can be obtained but the cost becomes high. In contrast,
No. 1 of the present invention. It can be seen that any one of Nos. 1 to 9 has good handleability of the sintered body and also has excellent magnetic properties. As described above, according to the present invention, it is possible to manufacture a plurality of MnAlC magnets having magnetic properties equivalent to or higher than those of the conventional manufacturing method by the powder encapsulation-extrusion method at a low cost and at the same time. This is an industrially excellent effect that can reduce the cost of the process.

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Claims (1)

Claims: 1. A method for producing a MnAlC-based alloy magnet, comprising the steps of:
A method for producing a MnAlC magnet, comprising sintering at 323 to 1473 K for a sintering time of 1 to 10 hr, and then molding by warm extrusion at an extrusion temperature of 933 to 1023 K.