JP2561704B2 - Method for manufacturing rare earth-Fe-B magnet - Google Patents

Description

The present invention relates to a method for producing a rare earth-Fe-B magnet,
More specifically, rare earth-Fe- that can obtain high magnetic performance
The present invention relates to a method for manufacturing a B-based magnet.

[Problems of the Invention]

With the recent demand for miniaturization and high efficiency of electric products, it is desired to make a magnet using a rare earth element having a high magnetic performance, and an alloy containing iron and boron as basic components as its materials. . That is, it is a rare earth-Fe-B magnet.

The so-called sintering method and the liquid quenching method are known as the technology for producing a rare earth-Fe-B magnet, and as a method having higher productivity than these methods, for example, JP-A-62-62
A casting method as disclosed in Japanese Patent Laid-Open No. 203302 has been proposed.

This casting method is different from the so-called sintering method and liquid quenching method, in which a molten metal of an alloy containing a rare earth element, iron and boron as basic components is poured into a mold to grow columnar crystals in one direction.
The magnet is cast by a so-called unidirectional solidification method.

It has been proposed to subject the ingot to hot working in order to form it into a desired shape and to improve the orientation of crystal axes.

Generally, in order to obtain a cast magnet having a high magnetic performance after hot working, it is necessary to orient the columnar crystals in one direction and make the crystal grains fine during casting. However, in the conventional unidirectional solidification method, although the ingot is cooled in one direction to make the columnar crystals anisotropic, the columnar crystals are made finer. No consideration was given to transfer control, the anisotropy of columnar crystals became incomplete, and satisfactory magnetic properties after hot working could not be obtained.

Therefore, the object of the present invention is to improve the anisotropy of the columnar crystals of the ingot during casting, thereby further refining the crystal grains, so that high magnetic performance after hot working, especially high coercive force Rare earth-Fe-B from which cast magnets can be obtained
It is to provide a method for manufacturing a system magnet.

[Structure of Invention]

The method for producing a rare earth-Fe-B magnet according to the present invention is a method for producing a rare earth-Fe-B magnet, which includes a step of casting an alloy containing a rare earth element, iron and boron as basic components and hot working, It is characterized in that the amounts of heat transfer in the molds differ by 90 ° during the casting.

In the above configuration, as the rare earth element, Y, La, Ce, P
r, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu are mentioned, and these 1 type, or 2 or more types are used in combination. Since the highest magnetic performance is obtained with Pr, it is preferable to practically use Pr, a combination of Pr and Nd, a combination of Ce, Pr and Nd, or the like.

The ratio of the rare earth element is appropriately 8 to 25 atom%. The main phase of a permanent magnet containing a rare earth element, iron, and boron as its basic components is R ₂ Fe ₁₄ B (R is a rare earth element), but if the rare earth element is less than 8 atomic%, the above compound is not formed and α-iron is formed. This is because the cubic crystal structure has the same structure, so that in order to obtain good magnetic performance, it is appropriate that the content be 25 atomic% or less.

A suitable boron content is 2 to 8 atomic%. If it is less than 2 atomic%, a rhombohedral R-Fe system cannot be obtained and a high coercive force cannot be obtained. On the other hand, in order to obtain good magnetic performance even by the casting method, it is suitable to be 8 atomic% or less. Because.

Further, a small amount of additional elements, such as Co, Al, Mo, Si, etc., and heavy rare earth elements, such as Dy, Tb, etc., are effective in improving the coercive force.

Co is effective in increasing the Curie point. In order to obtain a coercive force of 1 KOe or more, which is considered as a permanent magnet, it is preferable to use 50 atom% or less. Co basically replaces the Fe site to form R ₂ Co ₁₄ B, but this compound has a small crystal anisotropy magnetic field, and as the amount increases, the coercive force of the magnet as a whole decreases. Because.

Al has an effect of increasing the coercive force. The addition amount of Al is preferably 15 atomic% or less. Since Al is a non-magnetic element, the residual magnetic flux density decreases as the amount of Al added increases, and the residual magnetic flux density becomes less than that of hard ferrite when it exceeds 15 atom%.

And, to make the amount of heat transfer in the mold different by 90 ° during casting means to make the cooling rate on the side perpendicular to this side slower than the cooling rate on the side where the columnar crystals are to be oriented. Is. For example, heat insulation or heating of one side of the columnar crystals at right angles to the alignment direction may be considered as an example.

The cooling rate on the side of the columnar crystal to be oriented is at the center of the plate width.
It is necessary to set the temperature to 10 ° C / sec or more from 1300 ° C to 1000 ° C, and it is more preferable to set it to 50 ° C / sec or more in order to refine the crystal grains.

Next, as hot working, 500 ℃ or more, preferably 650 ℃
It is important to obtain high magnetic performance by cooling to ~ 1000 ° C or more, or once cooling to around room temperature, then reheating and processing at 500 ° C or more, and processing perpendicular to the direction in which columnar crystals develop. is there.

[Action]

In the method of manufacturing a rare earth-Fe-B magnet according to the present invention, a molten metal of an alloy containing a rare earth element, iron and boron as basic components is poured into a mold. At this time, by making a difference in the heat transfer amount of the mold in 90 ° different directions, the columnar crystals are developed on the side of the ingot where the columnar crystals are to be oriented, and the growth of columnar crystals on the one side differing by 90 ° is suppressed. Therefore, the orientation of crystal axes and the refinement of crystal grains are promoted to improve the magnetic performance.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a process chart of one embodiment of the present invention,
2 (a) is a schematic sectional view of the apparatus of the embodiment, and FIG. 2 (b) is a sectional view taken along the line EE in FIG. 2 (a). The present invention is not limited to this.

 S1, S2, ... In FIG. 1 indicate process numbers.

Two alloys of No. 1 and No. 2 shown in Table 1 were melted in an induction furnace (S1 in Fig. 1), and melt 2 was melted as shown in Fig. 2.
Mold designed to have different amounts of heat transfer in 90 ° different directions
10 is used for continuous casting (Fig. 1, S2). And 950
Hot rolling is performed by the roll 12 in the columnar crystal developing direction A and the undeveloped direction B shown in FIG. a)).

As shown in FIG. 2 (b), the mold 10 has an inside 20
It is a copper mold having a size of mm × 40 mm, and the cooling water 14 circulates on the outside thereof. An alumina board 11 of 10 mm × 20 mm is faced and inserted into the inside to insulate the heat, and a continuous ingot 15 of 20 mm × 20 mm is obtained.

This is annealed (S4 in FIG. 1) and further cut and ground (S5 in FIG. 1) to obtain a magnet as a product.

When the magnetic performance of the magnet 16 thus obtained was measured, the results shown in Table 2 were obtained.

By using continuous casting as described above, mass production of high-performance cast magnets becomes possible. Further, the present invention, in addition to the continuous casting method, cooling the ingot by creating an ingot.
It is naturally applicable to a batch-type manufacturing method of hot working.

〔The invention's effect〕

According to the present invention, a rare earth element including a step of casting and hot working an alloy containing a rare earth element, iron and boron as basic components-
In the method for producing an Fe-B magnet, there is provided a method for producing a rare earth-Fe-B magnet, characterized in that the amount of heat transfer in different directions of 90 ° in the mold is made different during the casting. Thereby, the orientation of the columnar crystals can be made uniform, and a lump with fine crystal grains can be obtained. By hot working this ingot, a cast magnet having high magnetic performance, especially high coercive force, can be obtained.

[Brief description of drawings]

FIG. 1 is a process drawing of an embodiment of the present invention, FIG. 2 (a) is a schematic sectional view of the apparatus of the same embodiment, and FIG. 2 (b) is a view taken along the line EE in FIG. 2 (a). FIG. [Explanation of reference symbols] 1 ... Manufacturing method of rare earth-Fe-B magnet 2 ... Molten metal 10 ... Mold 11 ... Alumina board 12 ... Roll 14 ... Cooling water.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tsutsuaki Oki 1-7-7 Karibadai, Nishi-ku, Kobe-shi, Hyogo (72) Inventor Mutsue Miyakawa 1010 Futamata, Hiraoka-cho, Kakogawa-shi, Hyogo (72) Inventor Yuri Tsuji Shimoda 2-31-31 Shinohara, Nada-ku, Kobe-shi, Hyogo (72) Inventor Tatsuya Shimoda 10017-16 Ochiai, Fujimi-cho, Suwa-gun, Nagano Prefecture

Claims (2)

(57) [Claims] 1. A rare earth-Fe-B including a step of casting and hot working an alloy containing a rare earth element, iron and boron as basic components.
A method for manufacturing a rare earth-Fe-B magnet, wherein the amount of heat transfer in the mold in different directions by 90 ° is made different during the casting. 2. The method for producing a rare earth-Fe-B magnet according to claim 1, wherein one surface side of the mold in different directions is heat-insulated or heated.