JP2904667B2 - Rare earth permanent magnet alloy - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an R ₂ Co ₁₇ rare earth permanent magnet alloy.

[0002]

2. Description of the Related Art As a rare earth permanent magnet alloy, R
₂ Co _17- based magnet alloys and R ₂ Fe ₁₄ B-based magnet alloys are generally used. Usually, R ₂ Fe ₁₄ B-based magnet alloys are widely used because their maximum energy products are larger, but their Curie temperature is as low as about 300 ° C, and their magnetic properties deteriorate extremely at high temperatures exceeding 100 ° C. It does not stand use. On the other hand, Curie temperature of R ₂ Co ₁₇ magnet alloy is about
Since 800 ° C. and higher, the magnetic properties becomes higher than R ₂ Fe ₁₄ B-based magnetic alloys at high temperatures, use at high temperatures R ₂ Co ₁₇
A system magnet alloy is used, and research and development are being pursued with the aim of achieving even higher characteristics while limiting applications.

It is well known that the R ₂ Co ₁₇ rare earth permanent magnet alloy has a fine cellular structure as its structure. This cellular structure is composed of an R ₂ Co ₁₇ phase having a cell diameter of 500 to 5000 ° and an RCo ₅ phase as a boundary phase having a width of 50 to 200 °.
It consists of phases. The R ₂ Co ₁₇ rare earth permanent magnet alloy is a pinning type magnet in which a coercive force is generated by pinning a domain wall into this fine cellular structure.
Therefore, the microstructure of the cellular structure and the magnetic properties are closely related to each other, and attempts have been made to enhance the magnetic properties by appropriately controlling the cellular structure. For example, JP-A-56-156734 and JP-A-56-156
In 735, a large coercive force exceeding 15KOe was obtained by controlling the distance between cells in a cellular structure to an appropriate size.

[0004]

However, the control of the cellular structure has not yet been sufficiently performed, and by controlling the cellular structure sufficiently, the R ₂ Co _17- based rare earth permanent magnet alloy can be further improved. Higher characteristics can be expected. An object of the present invention is to provide a rare-earth permanent magnet alloy exhibiting excellent high magnetic properties by precisely controlling the structure in a cell.

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies on fine cellular structures and magnetic properties. As a result, the composition in the cell has a great influence on the magnetic properties, and the composition in the cell is appropriately adjusted. By controlling this, the R ₂ Co ₁₇ permanent magnet having high residual magnetic flux density and high coercive force was successfully manufactured. That is, the gist of the present invention is, in terms of weight percentage, 24-28.
% Of R (R is one or more of rare earth elements), 5 to 30%
Fe, composed of 3 to 6% of Cu, 2 to 4% of Zr, and the balance of Co. The composition in the cell having a fine cellular structure is represented by atomic percentage and 8 ≦ R.
≦ 12, 5 ≦ Fe ≦ 40, 1 ≦ Cu ≦ 4, 0.1 ≦ Zr ≦ 3, Co remaining
Or a rare earth permanent magnet alloy comprising:

Hereinafter, the present invention will be described in detail. R ₂ Co ₁₇
A rare earth permanent magnet alloy is generally manufactured by the following steps. First, a predetermined amount of raw materials is weighed, and they are melted and cast in a melting furnace such as a high-frequency melting furnace or an arc furnace. Subsequently, the melted ingot is coarsely crushed using a jaw crusher, a stamp mill, a brown mill, etc., and thereafter, by a jet mill, a ball mill, etc.
Pulverize to a particle size of 1 to 50 μm. The finely pulverized R ₂ Co ₁₇ alloy is formed in a magnetic field,
Sintering at 0-1250 ° C, then 0-5
Solution solution at 0 ° C lower temperature. The time required for sintering and solution treatment is suitably 0.5 to 5 hours. Finally, aging treatment is performed. The aging treatment is usually carried out at 700 to 950 ° C. for a certain period of time as the first stage aging, followed by continuous cooling or multistage aging. In each of the above steps, when the R ₂ Co ₁₇ alloy is oxidized, the properties are significantly deteriorated. To prevent such deterioration, the steps are performed in a vacuum or in a non-oxidizing atmosphere.

[0007] Immediately after the completion of the solution treatment, the R ₂ Co ₁₇ alloy is T
The crystal structure of bCu ₇ type is shown.
Separates into ₂ Co ₁₇ phase and RCo ₅ phase to form a fine cellular structure. This cellular structure is formed during the first-stage aging, and the size of the cell is substantially determined by the temperature of the first-stage aging. The constituent elements are diffused by the subsequent continuous cooling and multi-stage aging, and the composition of the R ₂ Co ₁₇ phase forming the cell and the RCo ₅ phase forming the boundary change. R and Cu diffuse into the boundary phase, Co and Fe diffuse into the cell, and Zr hardly diffuses. As the composition of the R ₂ Co ₁₇ phase and the RCo ₅ phase changes, the properties of the R ₂ Co _17- based magnet alloy also change. Therefore, by appropriately controlling the composition in the cell, it is possible to manufacture a high-performance permanent magnet having a high residual magnetic flux density and a high coercive force.

[0008]

The composition of the R ₂ Co ₁₇ phase of the cell is determined for the following reasons. The amount of R in the cell is 8% or more in atomic% 12
% Or less because a large coercive force cannot be obtained if the amount of R is more than 12%. This is considered to be because the large amount of R means that the progress of the phase separation is insufficient, and therefore the domain wall pinning action is insufficient. Further, in order to maintain the crystal structure of the cell in the R ₂ Co ₁₇ phase, the amount of R in the cell needs to be 8% or more.
R is one or more of the rare earth elements, including Y La, Ce, Pr, Nd, P
m, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and one or more mixed elements selected from Lu. If the amount of Fe contained in the R ₂ Co ₁₇ phase of the cell is less than 5 atomic%, the residual magnetic flux density of the R ₂ Co ₁₇ based magnet alloy will be small. This is considered to be because when the amount of Fe contained in the R ₂ Co ₁₇ phase is less than 5 atomic%, the saturation magnetization of the R ₂ Co ₁₇ phase becomes small. Therefore, in order to obtain a large residual magnetic flux density, it is sufficient to perform aging treatment so that the amount of Fe contained in the R ₂ Co ₁₇ phase of the cell becomes 5 atomic% or more, but it is contained in the cell.
If the Fe content exceeds 40 atomic%, the coercive force decreases. From the above viewpoint, the amount of Fe contained in the R ₂ Co ₁₇ phase of the cell is limited to 5 at% to 40 at%.

If the amount of Cu contained in the R ₂ Co ₁₇ phase of the cell exceeds 4 atomic%, the coercive force of the R ₂ Co _17- based magnet alloy becomes small. This is considered to be because when the amount of Cu contained in the R ₂ Co ₁₇ phase exceeds 4 atomic%, the crystal magnetic anisotropy of the R ₂ Co ₁₇ phase decreases. Therefore, in order to obtain a large coercive force, it is sufficient to perform aging treatment so that the amount of Cu contained in the R ₂ Co ₁₇ phase of the cell becomes 4 atomic% or less. Aging treatment is required, and there is a problem in manufacturing. From the above viewpoint, the amount of Cu contained in the R ₂ Co ₁₇ phase of the cell is limited to 1 atomic% or more and 4 atomic% or less.
When the amount of Zr in the cell exceeds 3 atomic%, the residual magnetic flux density of the permanent magnet decreases. Further, in order to reduce the content to less than 0.1 atomic%, aging treatment must be performed for a long time, which is unreasonable in production.

The composition of the R ₂ Co _17- based permanent magnet alloy is expressed in terms of weight percentage of 24-28% R (R is one or more of rare earth elements), 10-20% Fe, and 3-6% Cu, 2-4% Zr,
The reason for limiting the remainder to Co is as follows.
When the amount of R contained in the R ₂ Co ₁₇ permanent magnet alloy exceeds 28% by weight, Br decreases. If it is less than 24% by weight, the square shape will be poor. If the Fe content is less than 5% by weight, Br
Is reduced, and if it exceeds 30% by weight, the coercive force is reduced. Further, if the Zr content is less than 2% by weight, a sufficient coercive force cannot be obtained, and if it exceeds 4% by weight, the maximum energy product decreases. 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 reduced.

[0011]

EXAMPLES The embodiments of the present invention will be specifically described with reference to examples, but the present invention is not limited to these. (Example 1) The alloy composition was Sm 25.5, Fe 14, Cu 4.5, Zr 3,
After weighing the raw materials so as to be each residual Co by weight%, they were 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 by a jet mill to have an average particle size of about 5 μm. This alloy powder was compacted in a magnetic field, and the obtained compact was sintered at 1,200 ° C and solution-treated at 1,180 ° C.
Next, the aging treatment is performed as a first-stage aging, which is maintained at 850 ° C. for 2 hours, and then cooled at a cooling rate of 0.5 ° C./min to 600 ° C. and 500
Continuous cooling to 400 ° C and 400 ° C followed by rapid cooling to room temperature. The magnetic properties of the obtained permanent magnet were measured, the fine structure was observed with a transmission electron microscope, and each element in the fine structure cell was quantitatively analyzed with an energy dispersive X-ray analyzer. Table 1 shows the obtained results.

[0012]

[Table 1]

Example 2 The alloy composition was Sm 25.5, Fe 16 and Cu
A sintered body was prepared under the same conditions as in Example 1 except that 4.0, Zr 2, and the remaining Co were each wt%, and then subjected to the following aging treatment. That is, after holding at 870 ° C for 2 hours as the first stage aging,
At cooling rates of 50 ° C / min, 10 ° C / min and 1 ° C / min, respectively
It was cooled continuously to 400 ° C and quenched. The resulting permanent magnet is
The magnetic properties were measured, the fine structure was observed with a transmission electron microscope, and each element in the cell of the fine structure was quantitatively analyzed with an energy dispersive X-ray analyzer. Table 2 shows the obtained results.

[0014]

[Table 2]

Example 3 The alloy composition was Sm 25.0, Fe 20 and Cu
A sintered body was prepared under the same conditions as in Example 1 with 5.0, Zr 2.5, and the remaining Co being each wt%, and then subjected to the following aging treatment. That is, the first stage aging is 0.5 at 850 ° C,
After holding for 2, 10 hours, 1 hour at 700 ° C, 2 hours at 600 ° C, 5 hours
The multi-stage treatment was performed at 00 ° C. for 5 hours and at 400 ° C. for 10 hours. The magnetic properties of the obtained permanent magnet were measured, the microstructure was observed with a transmission electron microscope, and each element in the microstructure cell was quantitatively analyzed by an energy dispersive X-ray analyzer. Table 3 shows the obtained results.

[0016]

[Table 3]

[0017]

According to the present invention, a high-performance R ₂ Co ₁₇ permanent magnet alloy having a high residual magnetic flux density and a high coercive force can be obtained, and its industrial value is extremely high.

──────────────────────────────────────────────────の Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C22C 19/07 C22C 33/02

Claims (1)

(57) [Claims] (1) a weight percentage of 24 to 28% of R (R is one or more of rare earth elements), 5 to 30% of Fe, 3 to 6% of Cu,
Rare earth permanent magnet alloy consisting of 2-4% Zr, balance Co
There, in the composition is atomic percentage in the cell of the micro-fine cell-like structure, 8 ≦ R ≦ 12,5 ≦ Fe ≦ 40,1 ≦ Cu ≦ 4, 0.1 ≦ Zr ≦
3. A rare earth permanent magnet alloy characterized by the balance of Co.