JPS5910421B2 - Rare earth cobalt permanent magnet alloy - Google Patents

Description

Detailed Description of the Invention The present invention is based on an R2T17 intermetallic compound composed of a rare earth metal (a mixture of R=5m and Y) and a 3d transition metal (a mixture of T=C0, Fe, and Cu). A permanent magnet alloy has a high residual magnetic flux density by reducing the non-magnetic Cu component in the constituent materials compared to conventional permanent magnet alloys made of the above components while maintaining the minimum practical coercive force. The present invention relates to a permanent magnet alloy characterized by the following characteristics:

Conventional! ) In intermediates of RCo6 and R2C017-based intermetallic compounds, R(C0, Fe, Cu)z in which the Co component or the composite component of Co and Fe is partially replaced with Cu.
It is known that a composition of (Z=5.0 to 8.5) is an excellent permanent magnet material.

Therefore, the present inventors subsequently investigated the above-mentioned composition alloys and found that even in low Cu concentration composition alloys in which the Cu component is less than 10.5% in atomic ratio, the coercive force is still sufficient for practical use, although the coercive force is reduced. It has been found that within the range of 3 to 5 (0e) contributes to an increase in residual magnetic flux density. Traditionally, in applications of permanent magnets, permanent magnets are rarely used alone; usually, a magnetic circuit is constructed of the magnet body and a yoke made of electromagnetic soft iron, etc., and the permanent magnet is generated. A method is adopted that makes effective use of magnetic flux.

In this case, the self-demagnetization caused by a single permanent magnet is alleviated, so in actual application fields, the coercive force of the magnet body is supplemented by configuring a magnetic circuit according to the purpose. Rare-earth cobalt-based permanent magnets have developed as high coercive force magnets since their initial development and have continued to this day, but they have limited application. It is estimated from the above that the residual magnetic flux density of alnico magnets (12 to 13
KG), only 20-30% lower values are obtained. For this reason, limitations are expected in the field of application. The present inventors solved the above-mentioned limitations of rare earth cobalt-based permanent magnet alloys by first using Y, which has a higher saturation magnetic flux density than Sm.
By replacing a part of the magnetic flux density, an increase in magnetic flux density was obtained.
No. 27797).

However, the gist of the invention according to the patent application depends on having a high energy product at the same time as a high magnetic flux density, and when considered from the magnet operating point (permeance coefficient) in the actual application field, In order to induce the above coercive force, a content of 10.5 atomic % or more of the Cu component, which exhibits properties contributing to an increase in coercive force, was required. However, considering the practical magnet operating point (for example, in a small precision motor, the permeance coefficient -B/H = 2 to 4), it is 3 to 5.
If a coercive force of 0e is ensured, sufficient protection is provided against self-demagnetization. The gist of the present invention is 3 to 5K for the reasons mentioned above.
In order to generate a high magnetic flux density while ensuring a coercive force of 0e, the Cu component in the constituent materials was reduced to the necessary minimum.
The purpose is to improve the residual magnetic flux density, and the permissible range of each component is less than 0.2 to 5.0 f) in terms of atomic ratio.
Sm: 6.7 to less than 12.2%, Fe: 0.4 to 12.
Less than 4%, Cu: 8.0 to less than 10.5%, CO: 64
．． The present invention can be most effectively realized when the composition amount is within the range of 8 to less than 80.0%.

Next, the reason for limiting the components of the permanent magnet alloy of the present invention will be explained. The following percentages shall represent atomic ratios. The rare earth component and 3d transition metal component ratio is within the range that should form an R2T, 7-based intermetallic compound (11.7 to 12.4 (:F6)
The effective value is determined from the range that does not increase the saturation magnetic flux density of Y and decrease the coercive force due to excessive inclusion of Y.
: 0.2 to less than 5.0%, Sm: limited to 6.7 to less than 12.2%. The Fe component, which shows a similar relationship between Br and Hc, works most effectively when it is less than 0.4 to 12.4%.
The Cu component is regulated by coercivity, but it should be kept to the necessary minimum (~
It can be reduced to 8.0 (F6) to maintain the coercive force of 3K0e).On the other hand, if it exceeds 10.5f, the meaning of the present invention is lost, so it needs to be less than 10.5%. The remainder is covered by CO. By adjusting the composition above, coercive force (Hc=
It has a coercive force of 3 to 5.5K0e) and a residual magnetic flux density Br.
It has been found that the weight can be easily increased to a range of 10 to 11 kg.

The general manufacturing process of the permanent magnet alloy according to the present invention includes weighing each component element, melting, crushing, magnetic field forming, sintering, solution treatment,
Consists of annealing. Hereinafter, the present invention will be explained in detail with reference to Examples. Example-1 Sm0.9Y0.1(COO.9-XFeO.lOCu
x) With a compositional formula of 7°2 and X as a parameter, seven types of alloys shown in Table 1 were arc melted in Ar, and ingots were produced in a water-cooled copper mold.

Table 1 (atomic percent) This ingot was crushed to a particle size of approximately 20 μm, and
Pressure molding was performed in a magnetic field of 0e.

Next, the molded body was placed in a vacuum of about 10-5 mmH9 at 1210°C.
℃ for 1 hour, and then rapidly cooled to room temperature at an average rate of 10° C./sec. This sintered body was reheated at 800° C. for 30 minutes, and then cooled in a furnace to room temperature. When the magnetic properties of the sintered alloy thus obtained were measured, as shown in Figure 1, the coercive force was maximum at X = 0.12 and rapidly decreased below X = 0.10. Ta. On the other hand, the residual magnetization increased as the Cu content increased, and when X=0.09, Br=11KG.

From the combination of coercive force and residual magnetization, the maximum energy product is X = 0.11 to 0.12, that is, the Cu component is approximately 10%
It was found that the maximum value was obtained when . Example-2 Sm: 10.9%, Y: 1.3f), Fe: 8.0%,
An ingot was obtained from an alloy consisting of Cu: 10.0% and CO: 69.8% in the same manner as in Example-1.

This ingot was crushed to a particle size of approximately 10 μm, and Example-
The same heat treatment as in 1 was performed. When the magnetic properties of this sintered alloy were measured, the following values were obtained. As detailed above, the permanent magnet alloy of the present invention has C as a non-magnetic component among the component elements.
The present invention provides a permanent magnet alloy mainly composed of R2Tl7 intermetallic compounds that exhibits high residual magnetic flux density by reducing the amount of u compared to conventional compositions.

[Brief explanation of drawings]

Figure 1 shows SmO. ,YO. l(COO.9-XFeO.
1OCux) 72 with respect to X,
FIG. 2 shows the hysteresis curve of the sample of Example-2.

Claims (1)

[Claims] 1 Rare earth component (consisting of Sm and Y) in atomic ratio 11.
7 to less than 12.4%, Fe: 0.4 to less than 12.4%,
Cu: 8.0 to less than 10.5%, Co: 64.8 to 80
．． It has a composition amount within a range of less than 0%, and among the rare earth components, Y is 0.2 to less than 5.0%, and Sm is 6.7 to 12.0%.
Permanent magnetic alloy characterized in that it contains less than 2%.