JPH0427287B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention uses samarium (Sm), cobalt (Co), copper (Cu), iron (Fe), zirconium (Zr)
In a ferromagnetic alloy mainly composed of the Sm ₂ (CoFe) ₁₇ compound, if the ratio of the contents of Co, Cu, Fe, and Zr is selected appropriately, a high coercive force can be obtained even if the Fe content is increased. The present invention relates to a permanent magnet material that is characterized in that, as a result, a high-performance magnet can be produced at low cost. Rare earth metals (R) and cobalt form various intermetallic compounds. Among them, RCO ₅ was first used as a permanent magnet material, especially SmCo ₅
was able to produce a much larger energy product than conventional alnico magnets and ferrite magnets. At present, RCo _5- based magnet materials are already well-established in industry, and demand is increasing year by year. Therefore, the next challenge for rare earth magnets was to achieve higher energy products and to create cheaper permanent magnets. The focus was on
Low ratio of R to Co, high saturation magnetization
It was an R ₂ Co ₁₇ compound. Among them, Sm ₂ Co ₁₇ has large magnetic anisotropy and is the most promising compound.
Currently, the mainstream method for magnetizing Sm ₂ Co ₁₇ compounds is to add Cu and Zr to obtain coercive force. However, the composition of the actually magnetized alloy is
The alloy had a ratio of Sm to transition metal of 1:7, not 2:17. Transition metals are represented by the symbol TM,
In SmTM ₂ , the value of 4πIs increases as the atomic ratio z of Sm and TM increases. Therefore, 1:
4πIs is higher when using a 2:17 alloy than when using a 7 alloy. However, in the conventional SmTM ₂ , the maximum coercive force was obtained when z was around 7, and when z was around 8.5 (2:17),
It was believed that almost no coercive force could be obtained. moreover,
Addition of Fe causes a decrease in coercive force, so Fe15wt%
It was said that if the maximum energy product with the highest degree is given, and Fe is increased beyond that, 4πIs will increase, but the coercive force will not be obtained commensurately, so the maximum energy product will start to decrease. The present invention has been made to improve these drawbacks. That is, 2: with lower Sm content than 1:7.
This was based on the knowledge that even if the composition of the alloy was shifted to around 17, a sufficiently high coercive force could be obtained even if the iron content was increased by appropriately changing the ratio between the transition metal elements. It is. To give a specific example, the typical composition of several alloy groups mainly composed of Sm (CoFe) ₇ , which have been conventionally magnetized, is Sm: 25.5wt%, Cu: 8wt%,
Fe: 15wt%, Zr: 1.5wt%, the rest is Co (Ojima
et al.: IEEE Trans. Magn., MAG13 (1977) 1317)
Alternatively, Sm: 27.5wt%, Cu: 10.9wt%, Fe:
8.2wt%, Ti: 0.6wt%, the rest is Co (Inomata et al.:
Appl.Phys.Letter. 30. (1977) 669) or
Sm: 25.9wt%, Cu: 7.9wt%, Fe: 15.3wt%,
Hf (hafnium): 1.3wt%, the rest is Co (Nezu et al.:
Proc.4th Int.work.R-Co Mag (1979) 437). When these three types of alloys are expressed in terms of composition ratio using atomic ratio, the first one containing Zr is Sm
(Co _0.677 Cu _0.1 Fe _0.21 Zr _0.013 ) _7.4 The following Ti-containing
Sm (Co _0.73 Cu _0.14 Fe _0.12 Ti _0.01 ) _6.7 , and the third
Those containing Hf are Sm (Co _0.674 Fe _0.22 Cu _0.1 Hf _0.006 ) _7.25
becomes. As can be seen from the above, the alloys of the future will be
The ratio of Sm to transition metal is around 1:7, and since the proportion of Sm, which is a scarce and very expensive raw material, is still relatively high, it has the disadvantage that it is not very cheap. In order to solve this problem, JP-A-55
-8455 or JP-A-55-21521, even if the ratio of Sm to transition metal is around 2:17,
Permanent magnetic materials having a coercive force of 6KOe or more have been proposed. These alloys have a lower Sm content than alloys with a ratio of 1:7, so they have the advantage of being able to produce cheaper permanent magnets, but the coercive force of about 6 to 7 KOe is still sufficient. The disadvantage is that it cannot be said to be a valid value. In addition, as is well known, Co is also a very expensive raw material along with Sm, so it is desirable to reduce the proportion of Co in order to provide a cheaper permanent magnet, and adding Fe increases 4πIs. In order to
Although it is beneficial for reducing the proportion of Co and improving the properties,
If the amount of Fe is too large, the coercive force will drop significantly, so 18 wt% was said to be the limit. As a result of various studies, the present inventors have found that by appropriately controlling the aging treatment conditions for magnetically hardening alloys mainly composed of Sm ₂ Co ₁₇ compounds, It was discovered that even when the amount of Fe exceeds 18 wt%, a sufficiently high coercive force of 8 KOe or more can be obtained, leading to the present invention. That is, the permanent magnet material of the present invention is characterized by having a composition range of 22.0≦Sm<24.0 4.0≦Cu≦10.0 18.0<Fe≦35.0 1.2≦Zr≦5.0 and the balance being Co in weight percentage. . The reason for limiting the composition range in the claims will be explained. The reason for setting the amount of Sm to be 22.0≦Sm<24.0 is that in order to obtain a high coercive force, z must be around 8.5, and when converted to wt%, this range corresponds to Fe.
In order _to obtain high saturation magnetization, it is better _to have a large amount of The amount of Cu within the composition range in the range,
Even if the amount of Zr is increased, 18 wt% is appropriate so that a saturation magnetization of 9 KG or more can be obtained and the alloy can be used as a practical material. In addition, the Cu amount and Zr amount are
4.0≦Cu so as to fit within the four-dimensional space.
≦10.0, 1.2≦Zr≦5.0 are appropriate. (Example) Alloys having the compositions shown in Table 1 were obtained using a high frequency melting furnace. Numbers in the table indicate wt%.

[Table] However, the remainder is cobalt. Ingots of these alloys were ground into powders with an average particle size of 3μ. The powder was press-molded in a magnetic field to form a compact with magnetic anisotropy. The molded body was sintered for 2 hours in an argon atmosphere. However, the sintering temperature is 1240 for alloys No. 1 and 2, respectively.
The temperature was 1220°C for alloy No. 3 and 1200°C for alloy No. 5. After sintering, a subsequent liquid treatment was performed at 1180° C. for 10 hours and quenched in an argon stream. Next, in order to obtain coercive force, the temperature was 2 hours at 850℃ and 2 hours at 800℃.
Then, multistage heat treatment was performed at 700°C for 5 hours.
The magnetic performance of the magnet thus obtained is shown in Table 2.

[Table] (Example 2) The ingot of the alloy used in Example 1 was
Homogenization was carried out in an argon atmosphere at the temperature shown in the table for 10 hours.

[Table] After the homogenization process, the ingot was rapidly cooled to room temperature in an argon stream. Next, in the ingot,
To obtain coercive force, multistage heat treatment was performed at 850°C for 2 hours, 800°C for 2 hours, and 700°C for 5 hours. These ingots were then ground into powder with an average particle size of 10 μC. The resulting powder is mixed with a thermosetting resin. The mixture of resin and magnetic powder was molded in a magnetic field of 20 KOe, and then the resin was thermally cured to obtain a resin-bonded magnet. Table 4 shows the magnetic performance of the resin-bonded magnet obtained.

[Table] (Example 3) Alloys having the compositions shown in Table 5 were obtained using a high frequency melting furnace. Numbers in the table indicate wt%. Alloy ingots of Alloy Nos. 8 to 11 were homogenized in an argon gas atmosphere at the temperatures shown in Table 6 for 4 hours.

【table】

[Table] After the homogenization process, the ingot was rapidly cooled to room temperature in an argon stream. Next, the ingot was heated to 800℃.
Aging heat treatment was performed for 2 hours, 8 hours, and 24 hours. These ingots were then ground into powder with an average particle size of 15 microns. The resulting powder is mixed with 2.2wt% of epoxy thermosetting resin and mixed in a mortar. A mixed powder of magnet powder and resin was molded in a magnetic field of 20 KOe, taken out from the mold, and then heated and hardened at 150° C. for 1 hour to obtain a resin-bonded magnet. The values of 4πIs and iHc of the magnetic properties of the magnet thus obtained are shown in FIGS. 1 and 2. As can be seen from this example, excellent magnetic properties were obtained even in the high iron region. Next, the ingots of Alloy 10 and Comparative Example were homogenized under the conditions shown in Table 6, and then aged at 800°C for 1 hour to 100 hours.
As shown in the figure. As can be seen from Figure 3, when aging treatment is performed for 24 hours or more, the coercive force improves regardless of the iron content, but for 4πIs, the iron content is 18wt%.
For samples with the following values, there was a large drop,
Higher magnetic properties can be obtained with samples containing more than 18wt%. The sintered magnet obtained in Example 1 had very high performance, and when used in a motor, a motor with extremely low current consumption was obtained. In other words, it is about 4 times smaller for the same size than the conventional one using ferrite.
It became possible to obtain double the torque. Although the resin-bonded magnets of Examples 2 and 3 have lower performance than sintered magnets, they have excellent machinability and mechanical strength, so they can be used to create magnets with complex shapes, small size magnets, or extremely thin magnets. is easy. Its magnetic properties are also overwhelmingly superior compared to non-rare earth magnets. When this type of magnet is used in a watch's rotor magnet, the cost of a roller magnet is reduced by nearly half that of a sintered magnet. This is due to good workability. The present invention provides a magnet with higher performance and better workability than conventional magnets, which is of great significance for various industries.

[Brief explanation of drawings]

FIGS. 1, 2, and 3 show the magnetic properties obtained by the method of the present invention. Figure 1 shows the V of the alloy of the present invention.
A diagram showing changes in the molar ratio of (Fe) and saturation magnetization (4πIs). Aging treatment to increase coercive force is 800℃
It was carried out for 2 hours, 800℃×8H, and 800℃×24H. Second
The figure shows changes in V(Fe) molar ratio and coercive force (iHc) of the alloy of the present invention. The aging treatment was carried out in the same manner as the data shown in FIG. FIG. 3 is a diagram showing the aging treatment time and changes in 4πIs and iHc of the alloy of the present invention.

Claims (1)

[Scope of Claims] 1 Permanent magnetic materials consisting of samarium (Sm), cobalt (Co), copper (Cu), iron (Fe), and zirconium (Zr), all of which are weight percentages of 22.0≦Sm<24.0 4.0≦ A permanent magnet material characterized in that the composition range is Cu≦10.0 18.0<Fe≦35.0 1.2≦Zr≦5.0 with the remainder being cobalt.