JPH01196103A - Manufacture of rare earth alloy magnet - Google Patents

Abstract

PURPOSE:To enable a crystallite aggregation type R-Fe-M group alloy magnet having high magnetism and being manufactured through a quenching method by bringing an alloy mainly comprising R2Fe14M type crystallites having means grain size of 1mum or below into contact with a ferromagnetic metal or alloy and heating these alloys and metals. CONSTITUTION:A rare earth alloy magnet manufactured through a high-speed quenching method or a magnet acquired by thermally treating the rare earth alloy magnet is an alloy which is made in a manner that large number of crystallites are dispersed into a crystallite aggregate or an amorphous alloy substrate. The main constituent is R2Fe14M type crystallites having means grain size of 1mum or below (where R is preferably a rare earth elements containing Nd as a principal ingredient, part of R may be preferably replaced with one kind or more of Zr, Nb, Ti, V, Hf, Ta and W, and M represents a semimetal employing B as an essential ingredient). However, the grain boundaries of the alloy have no magnetism or the alloy has poor workability even when the grain boundaries have magnetism. According to the method, the R2Fe14 group alloy brought in an anisotropic state is mixed with a magnetic substance having relatively high saturation magnetization such as Fe, Co or an alloy thereof, and heated and these metals are diffused to the grain boundaries of the R2Fe14M type crystlalites, thus manufacturing a rare earth magnet having high magnetism.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention mainly relates to anisotropic R -F e -M alloy magnets (R is a rare earth element, M is a semimetal whose essential component is B). ). The alloy magnet obtained by the method of the present invention has high magnetic properties and has good plastic workability and can be processed into a magnet with even higher magnetic properties.

(Prior art and its problems) In recent years, R-T-M (typically N d
-F e -B) type magnets have been developed, and these are manufactured by a sintering method (Japanese Patent Application Laid-Open No. 59-4600).
No. 8, etc.), or by a high-speed quenching method (Japanese Patent Application Laid-Open No. 60-9852, etc.).

Magnets produced by the sintering method are manufactured through the steps of melting raw materials, forming into ingots by casting, coarsely crushing, finely crushing, pressing, and sintering the ingots using a powder metallurgy process. Magnets produced by sintering generally have high magnetic anisotropy and excellent properties, but the manufacturing process is complicated, resulting in high costs and poor oxidation resistance. Furthermore, since the R2F 814M type microcrystalline grain boundaries generally have low magnetism, the magnetism as a whole is still insufficient.

On the other hand, magnets manufactured using the high-speed quenching method are manufactured by melting raw materials, high-speed quenching, coarse pulverization, and cold or warm pressing (or plastic working), requiring fewer steps, lower manufacturing costs, high coercive force, and oxidation resistance. It has the advantage of high performance. However, in order to obtain a magnet with high magnetic properties using the high-speed quenching method, a step of creating magnetic anisotropy is required. If an attempt is made to manufacture an inexpensive magnet by reducing the amount of expensive rare earth elements to 12 at % or less, the plastic working conditions will be severe, requiring high temperatures (for example, 750° C. or higher) and high pressures. In addition,
A significant decrease in coercive force also occurs. Therefore, the present invention etc.
-We tried adding Zr, Nb, Hf, Ta, W, etc. to M-based magnets, but even with R in the range of 55 to 12 at%, it still had a relatively high coercive force and a relatively high energy product. Although the magnet could be manufactured, the workability or deformability of this magnet is not improved.

Magnetism can be enhanced by containing excessive amounts of Fe and Co in the raw materials for alloy magnets made using this high-speed quenching method, and forming a grain boundary layer with a relatively large amount of Fe and Co around the precipitated R2Fe+4M type microcrystals. However, the grain boundary layer of alloy magnets manufactured using the high-speed quenching method is difficult to deform, making it difficult to create anisotropy.

Therefore, R-T-M has good magnetism and easy anisotropy.
It is desired to develop a method for manufacturing magnets.

(Object of the invention) The present invention provides a highly magnetic rare earth alloy magnet, particularly a microcrystalline aggregate type R-Fe-M alloy magnet manufactured by a rapid cooling method.
In particular, a magnetic alloy (R
is a rare earth element, which may be partially substituted with at least one of Zr, Nb, Hf, Ta, and W, and M is as described above).

The present invention particularly relates to microcrystal aggregate type R produced by a rapid cooling method or the like.
- It is an object of the present invention to provide a novel method for improving the magnetic properties and magnetic anisotropy of a T-M alloy magnet.

(Summary of the invention) The present invention is an alloy mainly composed of R2Fe+4M type microcrystals with an average particle size of 1 μm or less (wherein R is a rare earth element, and R
may be partially substituted with one or more of Zr, Nb, Ti, V, Hf, Ta, and W, and M is a metalloid containing B as an essential component) and a ferromagnetic metal or alloy. A rare earth alloy magnet with high magnetic properties is provided by a method for producing a rare earth alloy magnet, which is characterized in that the metal or alloy is diffused into the grain boundaries of R2Fe+4M type microcrystals by heating.

The present invention also provides a method for producing an anisotropic rare earth alloy magnet, which comprises further plastically working the alloy magnet thus obtained. Accordingly, a highly anisotropic magnet can be provided. The method of the present invention can be particularly effective when R is contained in an amount of 12 at % or less based on the total amount of the alloy.

(Detailed Description of the Invention) A rare earth alloy magnet produced by a high-speed quenching method or a magnet obtained by further heat-treating the same is a type in which a large number of microcrystals are dispersed in a microcrystalline aggregate or an amorphous alloy matrix. An alloy mainly composed of R2FezM type microcrystals with an average particle size of 1 μm or less (however, R is preferably a rare earth element mainly composed of Nd, and preferably a part of R is Zr, Nb, Ti).
, V, Hf, and Ta, and M is a metalloid containing B as an essential component).

However, this material has the disadvantage that the grain boundaries are non-magnetic or have poor workability even if they are magnetic. The method of the present invention mixes an anisotropic R2FezM alloy with a magnetic material with relatively high saturation magnetization, such as Fe, Co, or an alloy thereof, and heats the mixture, thereby forming an anisotropic R2FezM alloy at the grain boundaries of R2Fe14M type microcrystals. This metal is diffused to provide highly magnetic rare earth YNla stone. Further, an anisotropic magnetic material mixed with Fe, Co, etc. can be manufactured by subjecting an isotropic material to plastic working while heating.

The magnetic metal diffused into the grain boundaries is selected from Fe, Go, or alloys thereof. When these metals are heated for the diffusion process, they soften or partially become liquid and diffuse into the alloy magnet, forming a layer of this metal or alloy at the grain boundaries of the microcrystals. This diffusion layer itself is magnetic and further improves the magnetism of the original rare earth alloy magnet. The temperature required for diffusion is 40
0-900'C. At temperatures below this, the diffusion rate is slow and efficiency is poor. At higher temperatures R2F 81
The 4M type microcrystals become coarser and the magnetic properties begin to deteriorate.

Alloy Composition The magnet used in the present invention is an alloy mainly composed of R2FezM type microcrystals with an average grain size of 1 micron m or less (However, R is preferably a rare earth element mainly composed of Nd, and R is preferably a rare earth element mainly composed of Nd.
may be partially substituted with one or more of Zr, Nb, T1, V, Hf, Ta, and W, particularly Zr and Nb, and M is a metalloid containing B as an essential component). R is generally 5~
It is 20 at%, preferably 10 to 14 at%. In this preferred range, Zr, Nb, Mo, Hf, Ta, W
By adding additive elements selected from the above, the crystal structure can be made fine and uniform, and the coercive force can be maintained even when the ferromagnetic metal is diffused. M is a metalloid containing B as an essential component, and 50% or less is a metalloid such as Si, C, P, or S.

The Kenshita JJl alloy raw material is an R-Fe-M alloy in which microcrystal aggregates or microcrystals obtained by melting at a high temperature and then rapidly cooling are dispersed in an amorphous matrix. This liquid quenching method uses water to cool the surface of a metal rotating body.
This is a method of injecting molten metal from a nozzle and rapidly solidifying it at high speed to obtain a ribbon-shaped material.
In the case of this invention, the single roll method, that is, the method in which the molten metal is injected onto the circumferential surface of one rotating roll, is most suitable. When obtaining the magnet of this invention by the single roll method, the circumferential speed of the water-cooled rotating roll is:
It is desirable to set it within the range of 2 m/sec to 100 m/sec. The reason is that when the roll circumferential speed is less than 2 m/sec and when Loom/Sec.
This is because the coercive force iHc becomes low in any case exceeding sec. In order to obtain high coercive force and high energy product, the roll circumferential speed should be 5 to 30 m/sec.
It is desirable to do so. In this way, the roll circumferential speed 2~Lo
By rapidly solidifying the molten alloy having the above composition using a single roll method at a speed of
~200000e, magnetization 65~150 mu/
A magnet of gr is obtained. If the molten metal is directly rapidly solidified in this way, an amorphous and microcrystalline or extremely fine crystalline structure can be obtained, and as a result, a magnet with excellent magnetic properties as described above can be obtained. This can be processed according to the present invention to make it anisotropic and to have even higher properties.

The structure after quenching varies depending on the quenching conditions, but it consists of an amorphous alloy or a mixed structure of R2Fe+4M microcrystals and an amorphous alloy, but by annealing, the structure and size consisting of R2FezM microcrystals or amorphous and R2Fez+M microcrystals can be further controlled, Annealed materials may be treated by the method of the present invention since higher properties can be obtained. As for the microcrystalline phase, high properties can be obtained when the average particle size is within the range of less than 1 μm.

High properties can be obtained when the structure does not contain an amorphous phase.

The magnet rapidly solidified by the liquid quenching method may be annealed in an inert atmosphere or in vacuum at a temperature range of 300 to 900°C for 0001 to 50 hours. By performing such an annealing heat treatment, in the quenched magnet having the components targeted by the present invention, the properties become less sensitive to the quenching conditions, and stable properties can be easily obtained. Here, the annealing temperature is less than 300℃, there is no annealing effect, and 900℃
If it exceeds the
c decreases rapidly. Preferably 400-800'C
It is. Further, if the annealing time is less than 0.001 hours, there is no effect of annealing, and even if it exceeds 50 hours, the properties will not be improved any further and it will only be economically disadvantageous. Therefore, the annealing conditions were as described above.

It is preferable to further perform plastic working to make an anisotropic magnet. Any known technique can be used as a method for manufacturing an anisotropic magnet. Such a method includes a method in which a lump-like rapidly cooled magnet is passed between rolling rolls under the same temperature conditions as the annealing described above. For example, a powdered magnet pulverized to an average particle size of about 100 micrometers is stored in a metal container, and then rolled. Possible methods include passing it through a roll.

If the R-Fe-M alloy produced by high-speed quenching is in the form of a lump, it is ground to an average particle diameter of about 100 μm using a stamp mill, or otherwise formed into a shape convenient for diffusion treatment. The anisotropic magnets are used in their plate form and subjected to the next diffusion process.

After contacting the magnet with the diffusion magnetic raw metal, the above-described diffusion magnetic metal or alloy and the alloy magnet in coarse powder or other form are mixed or otherwise brought into contact with each other at a temperature of 400-900'C. At temperatures lower than 400° C., it is difficult for the magnetic metal to diffuse between the microcrystalline particles of the magnetic alloy.

Temperatures higher than 900°C are not preferred because the microcrystals become coarse. In this way, the liquid phase forming alloy diffuses between the magnetic alloy crystal grains. Using a hot press enables efficient diffusion.

There may be various methods for making this contact.

For example, both are mixed in the form of coarse powder and heated at the same time. Alternatively, mixing and heating may be performed as sequential steps. In the case of anisotropic powder, it is preferable to mix the powders together and then press them in a magnetic field and heat them. In the case of a magnet that has already been plastically worked into a magnetically anisotropic bulk magnet, it is possible to stack a thin plate of a magnetic metal for diffusion and a thin plate of an anisotropic magnet on top of each other and heat them under pressure. .

The rare earth magnet thus obtained has higher magnetic properties than conventional magnets as an isotropic or anisotropic magnet. This is because the ferromagnetic metal diffuses into the grain boundary layer, increasing the saturation magnetism of the entire magnet.

In addition, in the case of an isotropic magnet, warm plastic working can be further performed to improve the magnetic properties.

The present invention will be explained in detail below.

K family father-in-law (1) Nd+oFetaZr3B? , (2) MM6Nd
a F879B7 (MM is mesh metal), (3)
Nd+5Fe7sCO4A1+ SLt Ba(4)
A molten alloy was formed by a high frequency melting method so as to obtain a composition of Nd+2.5FetoCO+oB7, and the molten metal was sprayed onto a single copper roll at a circumferential speed of 30 m/sec for high-speed quenching. These alloys were coarsely ground into 60 meshes using a stamp mill. Next, among these, (2) and (3) above
, (4) was hot pressed at 657°C, 2 tons, for 30 minutes, and then at 700'C, 500k.
Plastic working was performed by applying unidirectional hot press compression under the conditions of 2.3 g/cm2.

Next, the above-mentioned (1) (coarsely pulverized powder not subjected to unidirectional Holad breath compression), (2) (thin plate as it was plastically worked), (3) (pulverized powder after plastic working),
(4) (Powder crushed after plastic working) (1) Add 150 meshes of Fe powder 8.8wt%, (2) Layer 13.9wt% Fe9oB+o thin film (relative to the magnet), (3) 150 meshes Added 9.3wt% of Co powder of mesh, (4) 150 mesh of Fe 70CO102rao
Added 199% powder. These were then each incubated at (1) 680°C and 500 kg/cm2.
0 hour hot press processing, (2) Heating at 620°C for 120 hours, (3) Magnetic field forming and hot pressing at 6800C, 500 kg/cm2 for 24 hours, (3) Magnetic field forming, 700°C, 500 kg/cm2
Then, hot pressing was performed to diffuse the low melting point metal or alloy into the grain boundaries of the magnet alloy.

The magnetic properties of the magnet thus manufactured were measured and the results shown in Table 1 were obtained.

A magnet was manufactured using raw materials prepared so as to finally obtain the same composition as the magnet alloy of the example.

Namely (1) Nd9Fea. Zrz7B6.3, (2
) MM51N d a, a F eao6Ba, a
(MM is mesh metal), (3) Nd++, tFe
e7.5COI3.6A10.9S 1o9B! ,,
4 (4) Nd+.

The raw materials were weighed so as to obtain a composition of Fe7oCO+oZr4.4B6.6, and the method of the example was carried out.

However, the final contact with ferromagnetic metals or alloys such as Fe and Co was not made. Table 1 shows the magnetic properties of the anisotropic magnet thus produced.

(Operation and Effect) Comparing the Examples and Comparative Examples, it can be seen that the characteristics of the magnet manufactured by the method of the present invention are extremely high. Fe is used as a raw material for alloy magnets from the beginning.

Adding excessive amount of ferromagnetic metal such as Co or alloy to R2Fe
It can be seen that the magnet of the present invention has a larger energy product than the case where the metal or alloy is formed at the grain boundaries of +4M type microcrystals. As described above, according to the present invention, it has become possible to improve magnetic properties by utilizing a low melting point ferromagnetic grain boundary layer and to efficiently carry out plastic deformation at low temperatures.

Claims (2)

[Claims] (1) Alloy mainly composed of R_2Fe_1_4M type microcrystals with an average particle size of 1 μm or less (However, R is a rare earth element, and R
may be partially substituted with one or more of Zr, Nb, Ti, V, Hf, Ta, and W, and M is a metalloid containing B as an essential component) and a ferromagnetic metal or alloy. A method for producing a rare earth alloy magnet, comprising: heating the metal or alloy to diffuse the metal or alloy into the grain boundaries of R_2Fe_4M type microcrystals. (2) Isotropic alloy mainly composed of R_2Fe_1_4M type microcrystals with an average particle size of 1 μm or less (However, R is a rare earth element, and a part of R is Zr, Nb, Ti, V, Hf, Ta,
W may be substituted with one or more types of W, M is a metalloid containing B as an essential component) is subjected to warm plastic working to form an anisotropic magnet, and a ferromagnetic metal or alloy is brought into contact with the anisotropic magnet and heated. A method for manufacturing a rare earth alloy magnet, characterized in that the metal or alloy is diffused into the grain boundaries of R_2Fe_1_4M type microcrystals.