JP2001059144A - Alloy ribbon and sintered permanent magnet for permanent magnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an alloy ribbon for permanent magnet having high magnetic properties and a sintered permanent magnet using the same. SOLUTION: This is an alloy ribbon for permanent magnet obtained by quenching an alloy melt mainly composed of R, T, and B with a quenching roll, and has an α-Fe phase having an average particle size of 0.1 to 20 μm.
1-20 μm R-rich phase, 0.1-10 μm R _x T
₄ B ₄ phase (x = 1 + ε) and 0.1~20μm of _{R 2}
The volume ratio of the four-phase coexistence region in which the T ₁₄ B phase is finely dispersed is 1 to 10% of the whole volume, and the fine chill having an average particle size of 3 μm or less present on the cooling surface side in contact with the quenching roll. The volume ratio of the crystal is 1 to 30% of the total volume, and the above four-phase coexistence region and the rest other than the chill crystal are R-rich phase,
R _x T ₄ B ₄ phase and _R 2 _{T 14} B phase, or composed of R-rich phase and _R 2 _{T 14} B phase.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a permanent magnet alloy ribbon (hereinafter simply referred to as "alloy ribbon") which is a main raw material of an RTB-based permanent magnet having excellent magnetic properties, and to the use thereof. To a sintered permanent magnet.

[0002]

2. Description of the Related Art Permanent magnets are used in a wide range of fields, from general home appliances to peripheral terminals of large computers and medical equipment.
One of electronic materials. Further, in recent years, permanent magnets have been required to have higher performance from the viewpoint of miniaturization and weight reduction of computers and communication devices, high efficiency, and further, environmental protection and energy saving.

[0003] Among the magnet alloys used for permanent magnets, R
-TB magnetic alloy has excellent magnetic properties,
Usually die casting or strip casting
It is manufactured by Mold casting method melted in crucible
The magnet alloy is cast into a metal mold, and a block-shaped ingot is formed.
The method of manufacturing makes it easy to control the composition of the magnet alloy.
It is widely used because of its points. However, gold
The mold casting method is used between the mold and the magnet alloy and within the magnet alloy.
Heat conduction speed is slow, so it takes time to cool the magnet alloy.
It takes time, so primary γ-F
e phase precipitates and after cooling, a particle size of 10 μm
The upper α-Fe phase remains. Further R₂T₁₄Take phase B
R-rich phase and R _xT₄B₄Phase size also increases
There is a problem. In addition, the ingot surface near the mold and the ingot
Because the cooling rate is different inside, α-Fe phase and R-rich
Variations in particle size occur in phases and the like. As a result,
It becomes difficult to finely pulverize
The particle size distribution of the powder becomes uneven. Therefore, the distribution of fine powder
The orientation and the sinterability of the molded body are deteriorated and finally obtained
There is also a problem that the magnetic properties of the magnet are adversely affected.

[0004] On the other hand, the strip casting method is a method in which a melt of a magnetic alloy is continuously supplied to a single-roll or twin-roll quenching roll to produce an alloy ribbon having a thickness of 0.01 to 5 mm. is there. This method makes it possible to control the precipitation of the α-Fe phase by controlling the quenching condition of the molten alloy, or to finely disperse the R-rich phase or R _x T ₄ B ₄ phase to make the structure uniform. The high magnetic properties of RT-
This is a method by which a B-based magnet can be manufactured. Researches on the structure of strip casts (alloy ribbons obtained by strip casting) for the purpose of improving magnetic properties have been conducted so far. Patent No. 2639609 discloses the precipitation morphology of α-Fe phase during strip casting and Paying attention to the structure, an alloy ribbon characterized in that α-Fe having a particle size of less than 10 μm is finely dispersed as peritectic nuclei in the main phase crystal grains is disclosed in Japanese Patent No. 2665590 and Japanese Patent Application Laid-Open No. 7-17-17.
No. 6414 proposes alloy ribbons which are substantially free from the segregation of the α-Fe phase. In Japanese Patent Application Laid-Open No. Hei 10-317110, attention was paid to a fine chill crystal structure generated near the cooling surface, and the average generation ratio was 5%.
% Or less has been proposed.

[0005]

Alloy strip for obtained by the strip casting method [0005], alpha-Fe phase, R-rich _phase, 4-phase coexisting composed R _x T 4 _{B 4} phase and _R 2 _{T 14} B phase Attention has been paid to the chill crystals generated in the region and on the cooling surface side, and there has been little research on the relationship between their precipitation morphology and the structure and the magnetic properties. Therefore, an object of the present invention is to provide a thin alloy ribbon and a sintered permanent magnet using the same that improve the magnetic properties by positively utilizing the four-phase coexistence region and the chill crystal.

[0006]

Means for Solving the Problems The present inventors have developed an α-Fe phase, an R-rich phase, an R _x T ₄ B ₄ phase and an R ₂ phase which are precipitated by rapid cooling in a strip casting method.
Each particle size of the T ₁₄ B phase and the volume ratio of the coexistence region of the four phases are
It has been found that it greatly contributes to improvement of magnetic properties. Furthermore, it has been found that the presence of chill crystals having an average particle size of 3 μm or less at a predetermined ratio in the vicinity of the cooling surface enables the improvement of magnetic properties to be manifested at a sintering temperature lower than usual, thereby completing the present invention. . That is, the present invention mainly comprises R, T, B
(R is at least one or more rare earth elements selected from Pr, Nd, Tb and Dy, and T is Fe, Fe and C
o, a metal or alloy selected from Fe and M or a combination of Fe, Co and M, where M is Mg, Al, S
i, Ca, Ti, V, Cr, Mn, Ni, Cu, Zn,
Ga, Zr, Nb, Mo, Sn, Sb, Ta, W, Pb
And a quenching roll for quenching an alloy melt consisting of at least one metal selected from the group consisting of α-Fe phase having an average particle size of 0.1 to 20 μm. , 0.1-20 μm R-rich phase, 0.1-
10 μm R _x T ₄ B ₄ phase (x = 1 + ε, ε is a constant determined by R) and 0.1-20 μm R ₂ T
₁₄ A fine chill crystal in which the volume ratio of the four-phase coexistence region in which the B phase is finely dispersed is 1 to 10% of the whole volume, and which has an average particle size of 3 μm or less existing on the cooling surface side in contact with the quenching roll Is from 1 to 30% of the total volume, and the above-mentioned four-phase coexistence region and the rest other than the chill crystal are R-rich phase and R-rich phase.
_x T ₄ B ₄ phase and _R 2 _{T 14} B phase, or R-rich phase and _R 2 _{T 14} alloy ribbon for permanent magnets, characterized in that it consists of the B-phase, and a sintered permanent magnet produced by using the same is there.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION As described above, the alloy ribbon of the present invention is obtained by continuously casting an alloy melt mainly composed of R, T, and B on a single roll type or twin roll type quenching roll by a strip casting method. And quenched. The alloy composition obtained in the present invention is preferably 5 ≦ R ≦ 40 wt% in RTB, and in Fe, Fe or Co is 50 ≦ T ≦ 90 wt% in T;
When M is further added, M is 8 wt% or less, and 0.2 ≦ M.
B ≦ 8 wt%. Although the size of the alloy ribbon is arbitrary, it is usually 10 to 500 μm in thickness and 5 to 500 mm in width. The quenching condition when manufacturing alloy ribbons is to control the four-phase coexistence region and the precipitation of chill crystals by changing the material, thickness, diameter, roll peripheral speed, and the amount of hot water from the tundish of the roll. Can be. Specifically, by setting the peripheral speed of the roll to 1.0 to 5.0 m / sec and the speed of discharging the molten metal from the tundish to 2 to 10 kg / sec, the sheet thickness is 10 mm.
An alloy ribbon of 0 to 500 μm is obtained, and the four-phase coexistence region and the volume ratio of the chill crystal can be controlled within the above ranges.

The α-Fe phase, the R-rich phase, and the R _x T ₄ B ₄ phase (x is 1 + ε: ε is a constant determined by R, and ε is about 0.1, In general,
Nd: 0.10 to 0.11, Pr: 0.10 to 0.1
1, Tb: 0.14 to 0.16, Dy: 0.15 to 0.
16) and the average particle size of the R ₂ T ₁₄ B phase are 0.1-20 μm, 0.1-20 μm, 0.1
To 10 μm and 0.1 to 20 μm. Preferably, respectively, 0.1 to 10 μm, 0.1 to 10 μm
m, 0.1-5 μm, and 0.1-10 μm.
When each particle size of the above four phases is within the above range, when the fine powder is molded and sintered in a magnetic field, (fine α-Fe phase) + (fine R rich phase) ) + (reaction of fine _R x _{T 4 B} 4 phase) → (fine _R 2 _{T 14} B phase) occurs. The reaction of these fine particles in a very active, the R _{2 T} 14 _B phase that is oriented, R ₂ newly generated by the above reaction
The T ₁₄ B phase binds without disturbing its orientation. Further, the sinterability is improved due to the reaction between the fine phases, and as a result, the sintered density and the residual magnetic flux density are improved. When the particle size of each phase is out of the above range, the above reaction hardly occurs, and no remarkable change in orientation is recognized. α-Fe
The average particle size of the phase, the R-rich phase and the R ₂ T ₁₄ B phase can be determined by observing a secondary electron image or a reflected electron composition image of a cross section of the alloy ribbon. Further, the R _x T ₄ B ₄ phase containing a large amount of B is difficult to detect due to the reflection electron composition image was observed Auger electron image of the fracture surface, the average particle diameter of the same phase can be measured.

[0009] In the alloy ribbon of the present invention, the volume ratio of the four-phase coexistence region is in the range of 1 to 10% of the total volume, and particularly 2%.
~ 5% is preferred. When the volume ratio of the four-phase coexistence region exceeds 10%, the coercive force and the residual magnetic flux density are greatly reduced. If it is less than 1%, the residual magnetic flux density does not substantially improve. The volume ratio of the four-phase coexistence region can be obtained from a secondary electron image or a reflected electron composition image of the cross section of the alloy ribbon.

Further, when the alloy ribbon is rapidly cooled by a quenching roll, the alloy ribbon of the present invention has a fine chill having an average particle size of 3 μm or less generated in the vicinity of the cooling surface in contact with the quenching roll. It is characterized in that the volume ratio of crystals is 1 to 30% of the total volume. When the volume ratio of the chill crystals having an average particle diameter of 3 μm or less is within the above range, the fine powder having an average particle diameter of 3 μm or less obtained after finely pulverizing the alloy ribbon is a fine powder constituting the four-phase coexistence region. The reaction between the four phases can be promoted, and the reaction between the four phases can be developed at a sintering temperature lower by 10 to 50 ° C. than when no chill crystals are present. Also,
Even when sintering at a low temperature, it suppresses the grain growth of the R ₂ T ₁₄ B phase,
The sintering density and the holding power can be improved. However, the fine powder is very active and easily oxidized,
When the volume ratio of the chill crystals having an average particle size of 3 μm or less exceeds 30%, the holding power is reduced, and the above-mentioned remarkable effect is not obtained. The volume ratio of the chill crystals having an average particle size of 3 μm or less is as follows:
What is necessary is just to obtain | require from a reflection electron composition image or a polarizing microscope photograph of the cross section of an alloy ribbon. The alloy ribbon thus obtained is hydrogenated or mechanically crushed (jet mill, Brown mill, etc.), molded in a magnetic field, and heated under an inert atmosphere at 900.degree.
Sintering at a temperature of ~ 1150 ° C, and further 400 ~ 600 ° C
And a heat treatment is performed to obtain a sintered permanent magnet.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below.
However, the present invention is not limited to these. (Example 1, Comparative Example 1) Nd, Dy,
Electrolytic iron, Co, ferroboron, Al, and Cu were used.
And these raw materials are 30Nd-1D by weight ratio (%).
y-BAL. Fe-4Co-1.1B-0.3Al-
After compounding to a composition of 0.2 Cu,
Alloy ribbons were produced by the blasting method. At that time, the four phases coexist
The volume ratio of the region is 0 to 13.7%, and the volume ratio of the chill crystal is 1
Strip casting method to be 0-15%
The quenching conditions in were changed. Construct a four-phase coexistence region
Α-Fe phase, R rich phase, R_xT₄B₄Phase and R₂
T₁₄The average particle size of the B phase is 3 μm, 7 μm, and 1 μm, respectively.
m and 10 μm. Figure 1 shows the volume of the four-phase coexistence region
A backscattered electron image (magnification of 100) of a cross section of a 5% alloy ribbon.
0 times). The black part in the figure indicates the α-Fe phase,
The part is R₂T₁₄B-phase, white part is R-rich phase
You. R_xT₄B₄Phase has small particle size and reflection
Reflected electron composition due to the high content of B, which is difficult to detect electrons
R by image_xT ₄B₄It is difficult to measure the particle size of the phase. In FIG.
In the four-phase coexistence region, α-Fe phase, R-rich phase and
And R₂T₁₄The B phase is finely dispersed. Figure 2 shows the four phases
Auger electron image (magnification 10,000x) of B in the storage area
is there. Auger electrons at two points (point and point) in FIG.
The spectra are shown in FIGS. 3 and 4, respectively. This is
Contain more B than surrounding phases (points) in the four-phase coexistence region.
Phase (point, R_xT₄B₄Phase) can be confirmed. Further
And R_xT₄B₄When the particle size of the phase is about 1-3 μm
It was confirmed that there was. Next, hydrogen of the fabricated alloy ribbon
And dehydrogenation, and jets in a nitrogen stream
It was pulverized with a mill to obtain a fine powder having an average particle diameter of about 3 μm.
Thereafter, these fine powders are filled in a mold of a molding apparatus, and 1
Orientation in a magnetic field of 2 kOe, perpendicular to the magnetic field
1 ton / cm²Press molding. The obtained result
The mold was sintered at 1050 ° C. for 2 hours in an Ar atmosphere.
Then, it is cooled and further heated at 500 ° C. for 1 hour in an Ar atmosphere.
Heat treatment was performed to produce permanent magnets of various compositions. And
For these permanent magnets, the residual magnetic flux density was measured and obtained.
The results obtained are shown in FIG. As can be seen from FIG.
If the volume ratio of the phase coexistence region is less than 1%, the
No ascent was seen. In addition, the volume ratio of the four-phase coexistence region is
If it exceeds 10%, the volume ratio of the four-phase coexistence region is less than 1%
The reduction in the residual magnetic flux density was larger than in the case of (1). 4 phases
When the volume ratio of the existing area is in the range of 1 to 10%, the residual magnetic flux density
Degree, the effect is excellent, especially when the content is 2 to 5%.
Was.

(Example 2, Comparative Example 2) As starting materials,
Nd, Dy, electrolytic iron, Co, ferroboron, Al, Cu
It was used. And these materials are weight ratio (%) of 2
8Nd-0.3Dy-BAL. Fe-1Co-1.1B
-0.3Al-0.1Cu was blended, and then an alloy ribbon was produced by a strip casting method.
At that time, the melting and casting conditions in the strip casting method were changed so that the volume ratio of the four-phase coexistence region was 0 to 13.5% and the volume ratio of the chill crystals was 8 to 16%. Also, alpha-Fe phase constituting the four-phase coexisting region, R-rich _phase, the average particle size of the R _x T 4 _{B 4} phase and _R 2 _{T 1 4} B phase were respectively 3 [mu] m, 5 [mu] m, 1 [mu] m and 15 [mu] m. Auxiliary (45N) compatible with separately melted alloy ribbon
d-15Dy-BAL. Fe-20Co-0.5B-
1.0 Cu-0.5 Al (wt%)) was added and mixed, and then permanent magnets of various compositions were produced in the same manner as in Example 1 and Comparative Example 1. And the residual magnetic flux density was measured about these permanent magnets, and the obtained result was shown in FIG. As can be seen from FIG. 6, no increase in the residual magnetic flux density was observed when the volume ratio of the four-phase coexistence region was less than 1%. The volume ratio of the four-phase coexistence region is 10%.
, The decrease in residual magnetic flux density was larger than when the volume ratio of the four-phase coexistence region was less than 1%. When the volume ratio of the four-phase coexistence region is in the range of 1 to 10%, the residual magnetic flux density is increased, and an excellent effect is particularly recognized when the volume ratio is 2 to 5%.
Further, the change in the degree of crystal orientation of the sintered body depending on the volume ratio of the four-phase coexistence region was evaluated using the X-ray pole figure method. FIGS. 7 and 8 show (006) polar figures when the volume ratio of the four-phase coexistence region is 0.5% and 3%, respectively. From the comparison between the two figures, it was found that the contour lines were densely distributed and the degree of orientation was higher when the volume ratio of the four-phase coexistence region was 3% than when it was 0.5%.

Example 3 Nd, D as starting materials
y, electrolytic iron, Co, ferroboron, Al, and Cu were used. And these raw materials are 28Nd- by weight ratio (%).
0.3 Dy-BAL. Fe-1Co-1.1B-0.3
Al-0.1Cu was blended in the composition, and then an alloy ribbon was produced by a strip casting method. that time,
The melting and casting conditions in the strip casting method were changed so that the volume ratio of the four-phase coexistence region was 2.1% and the volume ratio of the chill crystals was 10%. Further, the α-Fe phase, the R-rich phase, and R _x T ₄ B constituting the four-phase coexistence region
The average particle size of each of the _four phases and the R ₂ T ₁₄ B phase is 20 μm.
m, 15 μm, 7 μm and 10 μm. 10 wt% of an auxiliary agent (described above) compatible with a separately melted alloy ribbon was added and mixed, and then permanent magnets of various compositions were produced in the same manner as in Example 1 and Comparative Example 1.

(Comparative Example 3) Nd, D
y, electrolytic iron, Co, ferroboron, Al, and Cu were used. And these raw materials are 28Nd- by weight ratio (%).
0.3 Dy-BAL. Fe-1Co-1.1B-0.3
Al-0.1Cu was blended in the composition, and then an alloy ribbon was produced by a strip casting method. that time,
Melting and casting conditions in the strip casting method were changed so that the volume ratio of the four-phase coexistence region was 1.9% and the volume ratio of the chill crystals was 0.2%. In addition, α-Fe phase, R-rich phase, and R _x T ₄
The average particle size of each of the B ₄ phase and the R ₂ T ₁₄ B phase is 3 μm.
m, 5 μm, 1 μm and 13 μm. 10 wt% of an auxiliary agent (described above) compatible with a separately melted alloy ribbon was added and mixed, and then permanent magnets of various compositions were produced in the same manner as in Example 1 and Comparative Example 1.

Comparative Example 4 Nd, D as starting materials
y, electrolytic iron, Co, ferroboron, Al, and Cu were used. And these raw materials are 28Nd- by weight ratio (%).
0.3 Dy-BAL. Fe-1Co-1.1B-0.3
Al-0.1Cu was blended in the composition, and then an alloy ribbon was produced by a strip casting method. that time,
The melting and casting conditions in the strip casting method were changed so that the volume ratio of the four-phase coexistence region was 0.0% and the volume ratio of the chill crystals was 0.5%. 10% by weight of an auxiliary agent (described above) compatible with the melted alloy ribbon is added.
And then mixed in the same manner as in Example 1 and Comparative Example 1.
Permanent magnets of various compositions were produced.

Table 1 shows each volume ratio (%) of the chill crystal and four-phase coexistence regions in the alloy ribbons in Examples 2 and 3 and Comparative Examples 3 and 4, the average particle size of each phase, and alloys thereof. The magnetic properties (residual magnetic flux density (Br), coercive force (iHc), and maximum energy product ((BH) max)) of the sintered magnet manufactured using the ribbon were shown. Further, Comparative Examples 3 and 4 using alloy ribbons having a low volume ratio of chilled crystals,
In order to sufficiently increase the density of the sintered body, it was necessary to perform sintering at 1100 ° C. On the other hand, in Example 2 in which chill crystals were contained in a volume ratio within the range specified in the present invention, 1070
A sintered body having a sufficient density was obtained at ℃. Further, it was confirmed that the coercive force was slightly lower. Table 2 shows the roll peripheral speed (m / m) in the strip casting method.
Sec), the tapping speed (kg / sec), and the plate thickness (μm) of the obtained alloy ribbon.

[0017]

[Table 1]

[Table 2]

[0018]

According to the present invention, an alloy ribbon having high magnetic properties and a sintered permanent magnet using the same can be obtained.

[Brief description of the drawings]

FIG. 1 is a backscattered electron image (1000 × magnification) of a four-phase coexistence region in a thin alloy ribbon for a permanent magnet.

FIG. 2 is an Auger electron image (magnification: 10,000 times) of boron in an alloy ribbon for a permanent magnet.

FIG. 3 is a diagram showing an Auger electron spectrum at a point in FIG. 2;

FIG. 4 is a diagram illustrating an Auger electron spectrum at a point in FIG. 2;

FIG. 5 shows the volume ratio of the four-phase coexistence region and the residual magnetic flux density (B
It is a figure which shows the relationship of r).

FIG. 6 shows the volume ratio of the four-phase coexistence region and the residual magnetic flux density (B
It is a figure which shows the relationship of r).

FIG. 7 is a (006) polar figure when the volume ratio of the four-phase coexistence region is 0.5%.

FIG. 8 shows a case where the volume ratio of the four-phase coexistence region is 3% (00
6) It is a polar figure.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Koji Sato, Inventor 2-1-1-5 Kitafu, Takefu-shi, Fukui Prefecture Shin-Etsu Kagaku Kogyo Co., Ltd. Magnetic Materials Research Laboratories (72) Kenji Yamamoto 2-1-1 Kitafu, Takefu-shi, Fukui Prefecture No.5 Shin-Etsu Kagaku Kogyo Co., Ltd. Magnetic Materials Research Laboratory (72) Inventor Takehisa Minowa 2-5-1 Kitafu, Takefu-shi, Fukui Prefecture Shin-Etsu Kagaku Kogyo Co., Ltd. Magnetic Materials Research Laboratory

Claims (3)

[Claims] 1. Mainly R, T, B (R is Pr, Nd,
At least one or more rare earth elements selected from Tb and Dy, T is a metal or alloy selected from Fe, Fe and Co, Fe and M or a combination of Fe, Co and M, M is Mg, Al, Si, Ca, Ti, V, C
r, Mn, Ni, Cu, Zn, Ga, Zr, Nb, M
o, Sn, Sb, Ta, W, Pb) is a thin alloy ribbon for permanent magnets obtained by quenching an alloy melt comprising at least one metal selected from the group consisting of: Α-Fe phase having a diameter of 0.1 to 20 μm, 0.1 to
20 μm R-rich phase, 0.1-10 μm R _x T ₄ B
The volume ratio of the four-phase coexistence region in which the _four phases (x = 1 + ε, ε is a constant determined by R) and the finely dispersed R ₂ T ₁₄ B phase of 0.1 to ₂₀ μm is 1 to 10% of the total volume. Further, the volume ratio of fine chill crystals having an average particle diameter of 3 μm or less present on the cooling surface side in contact with the quenching roll is 1 to 30% of the whole volume, and is other than the above four-phase coexistence region and the chill crystals. the balance R-rich _phase, R _x T _{4 B} 4 phase and _{R 2}
An alloy ribbon for a permanent magnet, comprising a T ₁₄ B phase or an R-rich phase and an R ₂ T ₁₄ B phase. 2. The volume ratio of the four-phase coexistence region is 2% in the total volume.
The alloy ribbon for a permanent magnet according to claim 1, wherein the content is about 5%. 3. A sintered permanent magnet using the alloy ribbon for a permanent magnet obtained in claim 1 or 2.