JPH06108190A - Rare earth permanent magnet alloy - Google Patents

Abstract

(57) [Summary] (Modified) [Structure] Percentage by weight: 24-28% R (R is at least one of rare earth elements), 10-20% Fe, 3-6% Cu, 2 ~
The Cu content in the cell of the fine cellular structure composed of 4% Zr and the balance Co and the R ₂ Co ₁₇ phase is 1 atom% or more and 3 atom% or more.
A rare earth permanent magnet alloy characterized by being in the following range. [Effect] According to the present invention, it is possible to produce a high-performance R ₂ Co ₁₇ series rare earth permanent magnet alloy having a coercive force exceeding 20 KOe, and its industrial utility value is extremely high.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an R ₂ Co ₁₇ type rare earth permanent magnet alloy.

[0002]

2. Description of the Related Art Currently, R ₂ is a rare earth permanent magnet alloy.
Co ₁₇ series magnet alloys and R ₂ Fe ₁₄ B series magnet alloys are generally used. Normally, the R ₂ Fe ₁₄ B-based magnet alloy is widely used because it has a larger maximum energy product. However, the R ₂ Fe ₁₄ B-based magnet alloy has a low Curie temperature of about 300 ° C, so it may exceed 100 ° C. At high temperatures, the magnetic properties deteriorate extremely and cannot be used. On the other hand, the Curie temperature of the R ₂ Co _17- based magnet alloy is as high as about 800 ° C., so the magnetic properties are higher than those of the R ₂ Fe ₁₄ B-based magnet alloy at high temperatures, and the R ₂ Co _17- based magnet alloy becomes R ₂ Co when used at high temperatures.
_{A 17-} based magnet alloy is used, and research and development is being pursued with the aim of achieving even higher properties while its application is limited.
It is well known that the R ₂ Co ₁₇ type rare earth permanent magnet alloy has a fine cellular structure as its structural structure. This cellular structure consists of cells consisting of R ₂ Co ₁₇ phase having a cell diameter of 500 to 5,000 Å and RCo ₅ phase which is a boundary phase with a width of 50 to 200 Å. The R ₂ Co ₁₇ type rare earth permanent magnet alloy is a pinning type magnet in which a coercive force is generated by pinning a domain wall in this fine cellular structure. Therefore,
The cellular structure, which is a fine structure, is closely related to the magnetic properties, and attempts have been made to enhance the magnetic properties by appropriately controlling the cellular structure. For example, in JP-A-56-156734 and JP-A-56-156735, a large coercive force exceeding 15 KOe can be obtained by controlling the distance between cells having a cellular structure to an appropriate size. There is.

[0003]

However, it cannot be said that the control of the cellular structure is still sufficiently performed, and the R ₂ Co ₁₇ type rare earth permanent magnet alloy is further improved by controlling the cellular structure sufficiently. Higher characteristics can be expected.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies on a fine cellular structure and magnetic characteristics, and as a result, the amount of Cu in the cells has a great influence on the magnetic characteristics, particularly the coercive force, By appropriately controlling the Cu content in the cell, we succeeded in producing a high-performance R ₂ Co ₁₇ system permanent magnet having a coercive force exceeding 20 KOe, and completed the present invention. The gist of the present invention is, by weight percentage, 24-28% R (R is one or more of rare earth elements), 10-20% Fe, 3-6% Cu, 2-4%.
Rare earth permanent magnet alloy, characterized in that the Cu content in the cells of the fine cellular structure consisting of Zr and the balance Co and consisting of the R ₂ Co ₁₇ phase is in the range of 1 atom% to 3 atom%. Is.

The present invention will be described in detail below. The R ₂ Co ₁₇ type rare earth permanent magnet alloy is generally manufactured by the following steps. First, a predetermined amount of raw material metal is weighed and melted in a melting furnace such as a high frequency melting furnace or an arc furnace to cast an ingot. Then, this ingot is roughly crushed using a jaw crusher, a stamp mill, a brown mill, etc.,
It is finely pulverized by a jet mill, a ball mill or the like so that the particle diameter becomes 1 to 50 μm. Next, this fine powder is compression-molded into a desired shape in a magnetic field, then sintered at 1,100-1,250 ° C, and subsequently solution-treated at a temperature 0-50 ° C lower than the sintering temperature. The time required for sintering and solution treatment is 0.5 to 5 hours.
Finally, as the aging treatment, the first stage aging is usually maintained at 700 to 950 ° C for a certain period of time, and then continuous cooling or multi-stage aging is performed. The above-mentioned steps are carried out in a vacuum or in a non-oxidizing atmosphere in order to prevent the deterioration of the characteristics of the R ₂ Co ₁₇ alloy when it is oxidized.

Immediately after completion of solution treatment, R ₂ Co ₁₇ alloy is TbC
Although it shows a u ₇ type crystal structure, R ₂
Separates into a Co ₁₇ phase and a RCo ₅ phase to form a fine cellular structure. The cellular structure is formed during the first-stage aging, and the size of the cell is determined by the temperature of the first-stage aging. Subsequent continuous cooling or multi-step aging causes each constituent element to diffuse, and the composition of the R ₂ Co ₁₇ phase forming the cell and the RCo ₅ phase forming the boundary changes. R and Cu diffuse into the boundary phase, Co and Fe diffuse into the cell, but Zr hardly diffuses. As the composition of the R ₂ Co ₁₇ phase and the RCo ₅ phase changes, the characteristics of the R ₂ Co ₁₇ system magnetic alloy also change.

The greatest feature of the present invention is that, of these constituent elements, the amount of Cu diffused in the cell was found to have a great effect on the coercive force, and the amount thereof was controlled. When the amount of Cu contained in the R ₂ Co ₁₇ phase constituting the cell exceeds 3 atomic%, the coercive force of the R ₂ Co ₁₇ system magnetic alloy becomes small, but this is due to the crystal magnetic anisotropy of the R ₂ Co ₁₇ phase. It is thought that this is because the sex becomes smaller. Therefore, in order to obtain a large coercive force,
The aging treatment may be performed so that the amount of Cu contained in the R ₂ Co ₁₇ phase of the cell is 3 atom% or less, but in order to reduce the amount of Cu to 1 atom% or less, a long aging treatment is required, which is disadvantageous in manufacturing. So
The amount of Cu contained in the R ₂ Co ₁₇ phase of the cell is 1 atom% or more and 3 atom% or more.
It is limited to the following range.

Next, the composition of the R ₂ Co ₁₇ type permanent magnet alloy is expressed by weight percentage of 24-28% R (R is one or more of rare earth elements), 10-20% Fe, 3-6%. The reason for limiting Cu to 2%, Zr of 2 to 4%, and the balance Co is as follows. R ₂
If the amount of R contained in the Co ₁₇ type permanent magnet alloy exceeds 28% by weight, Br decreases, and if it is less than 24% by weight, the squareness deteriorates. Here, R is Y including La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, T
One or two or more kinds of mixed elements selected from b, Dy, Ho, Er, Tm, Yb and Lu, and preferably Sm. Further, if the Fe content in the R ₂ Co ₁₇ system permanent magnet alloy is less than 10% by weight, Br will decrease, and if it exceeds 20% by weight, the coercive force will decrease, and if the Zr content is less than 2% by weight. Sufficient coercive force cannot be obtained, and if it exceeds 4% by weight, the maximum energy product decreases. Further, if the Cu content is less than 3% by weight, the coercive force will be low, and if it exceeds 6% by weight, Br will be lowered.

[0009]

EXAMPLES The embodiments of the present invention will be specifically described below with reference to examples, but the present invention is not limited thereto. (Example 1) Alloy composition is Sm25.5% by weight, Fe14% by weight, Cu
The raw material metals were weighed so as to be 4.5% by weight, 3% by weight Zr, and the balance Co, and then melted in a high-frequency melting furnace to produce an alloy ingot. The obtained alloy ingot was coarsely pulverized using a brown mill, and then finely pulverized with a jet mill. The average particle size of the alloy powder after pulverization was about 5 μm. This alloy powder was molded in a magnetic field, and the obtained molded body was sintered at 1,200 ° C and solution-treated at 1,180 ° C. Next, the aging treatment was first holding as aging at 850 ° C. for 2 hours, followed by continuous cooling to 400 ° C. at 5 ° C./min, 1 ° C./min, 0.2 ° C./min, and then rapid cooling. The magnetic properties of the obtained permanent magnet were measured, the fine structure was observed with a transmission electron microscope, and Cu of the composition in the cell of the fine structure was quantitatively analyzed with an energy dispersive X-ray analyzer. The results obtained are shown in Table 1.

[0010]

[Table 1]

Example 2 A sintered body was prepared under the same conditions as in Example 1 and then subjected to the following aging treatment. That is, as the first stage aging, it was held at 870 ° C for 1, 2, 5 and 10 hours, and then continuously cooled to 400 ° C at a cooling rate of 1 ° C / min and rapidly cooled. The magnetic properties of the obtained permanent magnet were measured, the microstructure was observed with a transmission electron microscope, and Cu of the composition in the cell of the microstructure was quantitatively analyzed with an energy dispersive X-ray analyzer. The obtained results are shown in Table 2.

[0012]

[Table 2]

(Example 3) A sintered body was produced under the same conditions as in Example 1, and then subjected to the following aging treatment. That is, the first-stage aging is 10 ° C at 800 ° C, 850 ° C, and 900 ° C, respectively.
Hold for 700 hours, 700 ℃ for 1 hour, 600 ℃ for 2 hours, 500 ℃
It was aged for 5 hours at 400 ° C for 10 hours at 400 ° C. The magnetic properties of the obtained permanent magnet were measured, the fine structure was observed with a transmission electron microscope, and Cu of the composition in the cell of the fine structure was quantitatively analyzed with an energy dispersive X-ray analyzer. The results obtained are shown in Table 3.

[0014]

[Table 3]

[0015]

According to the present invention, it is possible to produce a high-performance R ₂ Co ₁₇ type rare earth permanent magnet alloy having a coercive force exceeding 20 KOe, and its industrial utility value is extremely high.

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Claims (1)

[Claims] 1. In weight percentage, 24-28% R (R is at least one of rare earth elements), 10-20% Fe, 3-6% Cu,
It is characterized in that the Cu content in the cell of the fine cellular structure composed of ₂ to 4% of Zr and the balance of Co and of the R ₂ Co ₁₇ phase is in the range of 1 atom% or more and 3 atom% or less. Rare earth permanent magnet alloy.