JPS63216317A - Manufacture of radially oriented magnet - Google Patents

Abstract

PURPOSE:To obtain an anisotropic magnet whose shockproofness and distortion- resistance are excellent by a method wherein thin pieces or powder of an alloy composed of a rare-earth element, iron an boron are sealed hermetically into a metal container and the thin pieces or powder of said alloy are warm-deformed together with said metal container in the radial direction and in the inner direction with reference to the long axis of said metal container so that the density and the degree of orientation can be enhanced. CONSTITUTION:An alloy composed of a rare-earth element, iron and boron is melted to obtain a desired composition; it is then solidified in the form of an ingot, a ribbon, a thin belt, thin pieces, powder or the like; in the case of the ingot and the thin belt, this material is broken into pieces of a suitable size. After the powder or pieces have been filled in a metal container, the powder, pieces or the like are warm-deformed, together with said metal container, in the radial direction and in the inner direction with reference to the long axis of the metal container. The pieces, powder or the like filled in the metal container are deformed together with the metal container in the radial direction and in the inner direction with reference to the long axis of the metal container; they are made to be highly dense; the easy-to-magnetize direction becomes equal to the direction; the socalled anisotropy is obtained. The temperature for warm-working is preferably 600-1000 deg.C.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for manufacturing a permanent magnet, and more specifically, a method for manufacturing a radially oriented permanent magnet made of a rare earth-iron-boron alloy. It is related to.

(Prior Art) A permanent magnet material made of a rare earth-iron-boron alloy achieves excellent magnetic properties by not using expensive cobalt or the like as an essential component and by using a large amount of iron, which is an inexpensive industrial material. Until now, we have been working to further improve the magnetic properties,
Achieving good magnetic properties while using cheaper elements,
Alternatively, by improving processability, etc., we provide a rare earth-iron-boron alloy permanent magnet material that can replace conventional general permanent magnets such as rare earth cobalt permanent magnets and ferrite permanent magnets and compete with these permanent magnets. Research has been actively carried out for this purpose.

Rare earth-iron-boron alloy permanent magnets are disclosed in JP-A-59-64
Isotropic materials such as those disclosed in JP-A No. 739 and JP-A-59-
It is broadly classified into anisotropic materials such as those disclosed in No. 46008.

(Problems to be Solved by the Invention) Among anisotropic permanent magnets, plastic magnets using rare earth cobalt alloys are widely known as permanent magnets having anisotropy in radial orientation. Since the coercive force of boron alloys decreases when powdered, it has been difficult to manufacture radially oriented anisotropic magnets. The applicant filed a patent application in 1986-
This was proposed in No. 235481 (domestic priority application of Japanese Patent Application No. 102086/1986). A rare earth-iron-boron alloy material that has been quenched as a molten metal is plastically deformed in the thickness direction to give anisotropy in the thickness direction, and one or more thin strips are processed into a ring shape.
Since the method for manufacturing a radially oriented permanent magnet does not involve a powder processing step, it is possible to avoid the problem of a decrease in coercive force. However, the dimensions of the radially oriented permanent magnets that can be manufactured by this method are limited to those produced by rapid cooling of a molten metal, or to the dimensions of a magnet.

As a method for heavy processing of a rare earth-iron-boron alloy which is usually produced in the form of a thin ribbon by a molten metal quenching method, a processing method by rolling (for example, the method described in Tokumei No. 1983-235481) is used. Since deforming force is applied in the plate thickness direction, it is impossible to manufacture radially oriented magnets. In addition, according to the known hot press method, the powder material is deformed in the outer radial direction and in the pressing direction with the pressing direction as the central axis, but anisotropy in the pressing direction appears due to the deformation in the outside radial direction. . Further, it is possible to produce radially oriented products using a specially shaped mold, but the hot press method has low mass productivity and is difficult to perform strong processing.

(Means for Solving the Problems) The present inventors have researched a processing method capable of manufacturing a radially oriented rare earth-iron alloy permanent magnet having excellent magnetic properties, and as a result, the above-mentioned An alloy flake or powder is hermetically sealed in a metal container, and the alloy flake or powder is warmly deformed together with the metal container in a radial direction and inward direction relative to the long axis of the metal container. It was found that the objective was achieved.

Hereinafter, the configuration of the present invention will be explained in detail.

First, a rare earth-iron-boron alloy is dissolved to a desired composition,
This is solidified into ingots, ribbons, thin strips, flakes, powders, etc., and the obtained flakes, powders, etc. are subjected to warm deformation as they are, or in the case of ingots and thin strips, they are crushed into appropriate dimensions. and subjected to warm deformation. Its dimensions are number n
It can be any size from a large one to a small one of several μm.

In particular, is it produced from a solution using a high-speed quenching method? The crystal grains and powders have small crystal grain sizes and high coercive force, making it easy to obtain high properties.

The composition of the rare earth-iron-boron alloy used in the method of the present invention may be any composition having magnetic properties, but
Among the rare earth elements, the content of C. and La is 0 to 20 atoms based on the total rare earth elements. When the content of Co and La exceeds 20 atomic% based on the total rare earth elements,
This is because the magnetic properties deteriorate. In addition, the rare earth element is Y
shall be included.

Subsequently, the powder, flakes, etc. of desired dimensions are sealed in a metal container. A preferred method for this is to press the powder, flakes, etc. to a certain extent to prevent them from falling apart, and to increase the bulk density before placing them in a metal container. In this way, the powder, flakes, etc. are uniformly deformed within the metal container during warm deformation, and strong processing becomes possible.

In addition to this method, another preferred method is to pack the powder, flakes, etc. into a metal container and then compress them together with the container in any direction to prevent the powder, flakes, etc. from being packed unevenly in the container. It is. It is desirable to pack powder, flakes, etc. in the container as densely as possible to reduce the amount of gases such as oxygen that adversely affect magnetic properties.

Thereafter, flakes, powder, etc.
Since a metal container easily deforms during warm deformation, the flakes, powder, etc. packed inside it will be damaged along with the metal container.
It is deformed in the radial direction and inward direction with respect to the long axis of the metal container, resulting in high density, and the direction of easy magnetization is substantially aligned in that direction, resulting in so-called anisotropy. The temperature of warm working is preferably 600 to 1000°C, more preferably 650 to 800°C. Heating to this temperature can be done by any method such as electric furnace heating, but high-frequency induction heating, or a combination of electric furnace heating and high-frequency induction heating, is a major cause of deterioration of the magnetic properties of rare earth-iron-boron alloys. Short-term heating that can suppress grain growth becomes possible. The processing method may be any method such as sweezing, extrusion, drawing, and elongation forging. According to these processing methods, deformation pressure is mainly applied in any direction within the radial direction, so that the flakes, powder, etc. are deformed in this direction.

At this time, since the flakes, powder, etc. are restrained by the wall surface of the metal container, they are efficiently compressed in the radial direction, increasing their density and degree of orientation. Further, in processing, the above methods can also be combined. in this case,
Intermediate heating is often required, making the operation complicated, but it has the advantage that magnets with small dimensions can be manufactured by performing sweezing to a certain size and then extruding. Note that rolling may be performed in the middle of the processing process to reduce the cross-sectional dimension, but since rolling mainly causes deformation force in the length direction of the workpiece, it hardly contributes to the radial orientation. The rolling processing should be limited to a processing rate that allows the desired cross-sectional dimensions to be obtained, and the main processing must be performed by the method described above. By the way, if the processing rate of warm deformation in the radial direction, which is a feature of the present invention, is less than 50 inches, expressed as the ratio of the cross-sectional area of the metal container before and after deformation, the effect of improving magnetic properties will be small. On the other hand, 95%
Exceeding this is not preferable because the pressure required for processing becomes extremely high, the number of processing steps becomes extremely large, or a high output device is required, making it impossible to carry out a practical warm processing method. The shape of the metal container is usually cylindrical, but it may be of any shape as long as it can be processed at a desired processing rate in the radial direction. Further, it is natural that the dimensions of the metal container should be designed to further achieve the effects of the present invention, such as preventing destruction during processing and suppressing elongation deformation. In order to avoid contact between oxygen and the rare earth-iron-boron alloy, which are harmful to the magnetic properties, the inside of the metal container may be evacuated or the atmosphere may be an inert gas atmosphere.

Finally, after the warm processing is completed, the metal container is cut,
Remove it from the work piece by polishing or other methods and take out the magnet body. This is then processed into a product shape or further crushed to become a plastic magnet.

(Effects of the invention) When hot deformation of iron-boron alloy flakes, powder, etc. in a metal container is performed by the method described above, the magnetic properties are excellent, and a radially oriented magnet that can be used in motors, etc. is efficiently produced. will be able to be manufactured in In addition, as a specific effect, (
(b) grain growth is suppressed and deterioration of magnet properties due to grain growth is eliminated; (b) density and degree of orientation can be increased through efficient radial deformation; and (c) compared to sintered magnets. Since the crystal grains tend to be small, products with excellent impact resistance and distortion resistance can be obtained, and the processing is efficient, as the desired deformation can be achieved by applying high deformation force in a short time. ) Excellent anisotropy improves the magnetic properties, making it possible to achieve remarkable effects such as reducing the amount of rare earth elements used compared to the case of sintered magnets. Among these effects, those considered to be beneficial can be achieved as appropriate depending on the intended use, product specifications, required cost, etc.

The present invention will be further explained below using examples.

(Example) Example 1 13.596Nd, 80%Fe*6.5%B
(% is atomic %) alloy was melted and the amorphous alloy IJ
,l? We created a new version. After crushing this into thin pieces with an average size of 100 μm, they were crushed into thin pieces with a diameter of 25.51111 mm under a pressure of 3 tons/crrL2. It was pressed into a cylindrical block with a height of 20 mm, and 5 of these blocks were packed into a stainless steel circular tube (outer diameter 30 mm, length 150 mm, wall thickness 2 mm), and both ends of the tube were closed with welded lids. In this state, the furnace was heated to 700°C. A squeage process was performed to reduce the diameter of this circular tube. The obtained circular compact is radially oriented, the maximum energy product (BH) at the circumference is mag ゛25 MGOa, and the residual magnetic flux density Br is 11.0 kO.
It was e.

Comparative Example 1 A radially oriented magnet having the same composition and the same outer diameter as Example 1 was produced by a sintering method and its characteristics were measured, and the maximum energy product (BH) was 18 MGOe.

Comparative Example 2 The molten metal of an alloy having the same composition as Example 1 was rapidly cooled to 50 to 2
When we crushed it to 00 μm to make a glass magnet and measured its characteristics, the maximum energy product (BI()) was 12
It was MGOs.

maX.

Example 2 Pulverized flakes of quenched molten ribbon of an alloy having the same composition as in Example 1 were packed into an iron tube with an inner diameter of 40 mm together with an iron rod with a diameter of 16 mm, heated to 750"O, and extruded using an extrusion processing machine. The iron tube was machined so that its diameter was reduced to 22.5 mm. After removing the iron tube and iron rod, the obtained compact was radially oriented and the maximum energy at the circumference was Product (BH)
rnax, is 24.7MGO, residual magnetic flux density Br is 1
It was 0.6 ko.

Claims (1)

[Claims] 1. Rare earth elements (however, the content of Ce and La is 0 at % to 20 at % based on the total rare earth elements)-iron-boron permanent magnet alloy flakes or powder in a metal container. A method for manufacturing a radially oriented magnet, comprising: sealing the metal container; and warmly deforming the flakes or powder together with the metal container in a radial direction and inward with respect to the long axis of the metal container. 2. The method for manufacturing a radially oriented magnet according to claim 1, wherein the flake or powder is sealed in a metal container under an inert or vacuum atmosphere. 3. The method for manufacturing a radially oriented magnet according to claim 1 or 2, wherein the warm deformation temperature is 600 to 1000°C.