JPS6115943A - Rare earth permanent magnet thin strip - Google Patents

Abstract

PURPOSE:To develop a rare earth permanent magnet having high coercive force and superior workability by cooling rapidly at ultrahigh rate molten metal of rare earth magnet alloy having a specified compsn. to form it thin strip shape. CONSTITUTION:An Fe(or Co)-B-Si alloy contg. rare earth having the compsn. expressed by a formula (1) is melted. In the formula, T indicates one or 2 kinds of Fe or Co, R at least one kind among rare earth elements such as Y, La, Ce, Pr, Nd, Pm, Sm, and the others are as follows by weight: (a); 75-85%, (b); 5- 15%, (c) <10%, (x); 5-40%. Molten metal of the alloy is cooled ultrarapidly at >=10<3> deg.C/sec rate by body revolving at high speed or cooling body such as roll to make it thin strip shape of 30-300mum thickness. This is annealed at 700- 800 deg.C for about 1hr, and permanent magnet thin strip whose coercive force is improved remarkably and superior in workability is manufactured inexpensively.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to rare earth transition metal permanent magnets suitable for use in various electrical measuring instruments, communication devices, etc. This is an attempt to improve the iax characteristics.

(Prior Art) In recent years, there has been a growing demand for smaller size, lighter weight, higher performance, and higher reliability for various electrical measuring instruments, communication devices, and even micro motors. Therefore, as a permanent magnet used in the above-mentioned equipment, (BH)w
There is a need for materials with larger ax.

By the way, rare earth permanent magnets are known to be suitable for the above-mentioned applications, and these magnets have been developed as high coercive force magnets since their initial development, and have continued to this day. The problem was that magnetization was difficult and workability was even more difficult.

Such alloy-based magnets have high hardness and are difficult to process, so they have to be manufactured by the powder compaction-sintering method, for example, as shown in the manufacturing process in Figure 2. In addition to the high cost of materials, manufacturing costs were considerable, so the problem remained that the manufacturing costs were high.

This invention advantageously solves the above-mentioned problems, and is easy to process and requires a simple manufacturing process at low cost.
The purpose is to propose rare earth permanent magnets.

(Motivation for the Invention) As a result of extensive research in order to achieve the above problem, the inventors have adjusted the alloy composition of rare earth magnets, and have developed a recently developed so-called liquid magnet that produces thin ribbons directly from molten liquid. It has been found that the intended purpose can be advantageously achieved by utilizing the rapid cooling direct plate manufacturing method.

This invention is derived from the above findings.

(Means for Solving the Problems) The present invention provides a ribbon having a composition represented by the following chemical formula, wherein the ribbon has the composition on a cooling body whose cooling surface is renewed and moved at high speed. This is a rare earth permanent magnet thin ribbon obtained by subjecting the falling flow of molten metal to rapid solidification to form a thin ribbon, followed by heat treatment.

(Ta Bb S tc) 100-X RX
Here, 7: l: one or two selected from e, co, R: Y, La, Ce, Pr, Nd, Pm and 5I11
At least one selected from the following: a: 5 to 85 at%, b: 5 to 15 at%, c: 10 at% or less, x: 5 to 40 at%, the reason for limiting the component composition to the above range in this invention explain.

Both Fe and CO are equally useful components as ferromagnetic materials, but if the content is less than 75 at%, the saturation magnetization and eventually residual magnetization will decrease, while if the content exceeds 85 at%, the ribbon after quenching will be brittle. Therefore, the content needs to be 75 to 85 at% whether added alone or in combination.

B effectively contributes to improving mechanical properties, but if the content is less than 58 t%, the effect of addition is poor;
If it exceeds t%, it will harden and become brittle, so 5 to 1 sat%.
limited to the range of

Si is a useful component for increasing the hardness of permanent magnets, but if the content exceeds 10 at%, the ribbon will become extremely brittle after quenching, so the content is preferably 0.5 at or less than 10 at%. It is necessary to set it to 10at%.

Next, Y, La, Ce, Pr, Nd, pm, and Sm are all essential elements for improving coercive force.
If the content of these rare earth elements is less than 5 at%, the coercive force improvement effect will be poor, while if it is added in excess of 40 at%, the effect will not only reach saturation, but also be uneconomical. It was limited to a range of ~40at%.

Next, the manufacturing process of this invention alloy will be explained.

The molten metal adjusted to the preferred composition as described above is first formed into a ribbon having a thickness of about 30 to 300 μm by a ribbon forming method as shown in FIG. At this time, if the cooling rate is less than 103°C/S, the columnar crystal structure of the ribbon immediately after quenching will be destroyed, and it will be difficult to recover the magnetic properties even with the heat treatment described below. It is desirable to perform the cooling at a cooling rate of .

Since it is difficult to obtain sufficiently satisfactory magnetic properties of the thus obtained ribbon immediately after solidification, it is subsequently subjected to heat treatment.

Figure 1 shows (F 080 810 S'No) 80 manufactured by the twin roll method shown in Figure 3C above.
A thin strip with a thickness of 250 μm having a composition of N'fao,
The results of investigating the coercive force 1l-1c when heat treated in argon gas are shown in relation to the heat treatment temperature.

As is clear from the figure, the coercive force 1l-1c is significantly improved by annealing at a temperature of about 700 to 800°C for about 1 hour.

In addition, such a rapidly solidified ribbon is flexible and has excellent toughness, and
Even when bent by 80°, it did not break easily and therefore had excellent workability.

Therefore, the permanent magnet according to the present invention requires only a simple process as shown in FIG. 4, and as compared with the conventional process shown in FIG.

(Examples) Example 1 A molten metal having a composition of (Fe8G"105110)80N'20 was rapidly solidified by a twin roll method at a cooling rate of 103° C./S to form a ribbon with a thickness of 250 μm.

This ribbon was then subjected to heat treatment for 1 hour at various temperatures in an Ar atmosphere.

Table 1 below shows the results of examining the coercive force 1 dle of the obtained ribbon.

Five types of molten metals having the component compositions shown in Table 2 were rapidly solidified using the twin roll method at a cooling rate of 104°C/S to form a ribbon with a thickness of 150 μm, and then heated to 700 μm in an Ar atmosphere.
Annealing treatment was performed at ℃ for 1 hour.

The results of investigating the coercive force IHc of each obtained ribbon are as follows:
As shown in Table 2, all exhibit high coercive force.

Table 2 (Effects of the invention) Compared to conventional materials, the rare earth permanent magnet according to the invention has
Not only does it have excellent magnetic properties, but it can also significantly improve workability, and it also achieves lower costs.

[Brief explanation of the drawing]

FIG.
10) A graph showing the relationship between the annealing temperature and coercive force of a ribbon having a composition of 8ON'20. Figure 2 is a block diagram showing the manufacturing process of the powder compaction-sintering method. Figure 3 a, b , c, d, and e are all schematic diagrams showing the procedure for quenching molten metal into a ribbon, and FIG. 4 is a block diagram showing the manufacturing process of the liquid quenching direct plate manufacturing method.

Claims (1)

[Claims] 1. A ribbon having a composition represented by the following chemical formula,
The thin ribbon is made of a rare-earth permanent material that is obtained by receiving a falling flow of molten metal having the composition on a cooling body whose cooling surface renews and moves at high speed, forcing the rapid solidification to form a thin ribbon, and then heat-treating it. Magnetic ribbon. (T_aB_bSi_c)_1_0_0_-_xR_x
T: one or two selected from Fe and Co; R: at least one selected from Y, La, Ce, Pr, Nd, Pm and Sm; a: 75 to 85 at%; b: 5 to 15 at%, c: 10 at% or less, x: 5 to 40 at%.