JP2576672B2 - Rare earth-Fe-Co-B permanent magnet powder and bonded magnet with excellent magnetic anisotropy and corrosion resistance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention provides a magnetic recording medium having excellent magnetic anisotropy and corrosion resistance.
R-Fe-Co-B permanent magnet powder containing Fe, Co and B as main components, and an R-Fe-Co-B system The present invention relates to a bonded magnet manufactured using permanent magnet powder.

[Conventional technology]

The R-Fe-B-based alloy magnet powder has been mainly developed as a magnet powder for bonded magnets since the R-Fe-B-based alloy attracted attention as a permanent magnet material exhibiting excellent magnetic properties.

In general, bond magnets are inferior in magnetic properties compared to sintered magnets and the like of the same type as the contained magnet powder,
In recent years, its use range has been rapidly expanding because of its excellent physical strength and high degree of freedom in shape. The bonded magnet is formed by combining a magnet powder with an organic binder, a metal binder, and the like, and the magnetic characteristics of the bonded magnet are influenced by the magnetic characteristics of the magnet powder.

One of the R-Fe-B-based permanent magnet powders used for the production of the bonded magnet is R-Fe described in JP-A-1-132106.
-B-based permanent magnet powder.

This R-Fe-B permanent magnet powder is composed of a ferromagnetic phase of R ₂
Fe ₁₄ B type intermetallic compound phase (hereinafter, referred to as R ₂ Fe ₁₄ B type phase) the R-Fe-B base alloy as a main phase as a raw material, H ₂ atmosphere of this mother alloy materials a predetermined temperature range Heat treatment in RH _X and F
After prompting phase transformation to each phase of e ₂ B and the balance Fe, H ₂ with deionized H ₂ steps
Is removed from the raw material, and the ferromagnetic phase R ₂ Fe
₁₄ B type phase was formed, and the resulting R-Fe
The structure of the B-based permanent magnet powder has an average particle size of 0.05 to 3 μm.
Has a texture mainly composed of a recrystallized microstructure of the R ₂ Fe ₁₄ B type phase.

Furthermore, R-Fe-Co is disclosed in JP-A-1-132106.
-B-based permanent magnet powder is described.
Even in the case of the -Fe-Co-B system, a part of Fe is replaced with Co as described above, and recrystallization of an extremely fine R ₂ (Fe, Co) ₁₄ B type phase having an average particle size of 0.05 to 3 μm. It is an organizational structure with the organization as the main phase.

[Problems to be solved by the invention]

The R-Fe-Co-B permanent magnet powder having the above-mentioned conventional recrystallized structure has (1) magnetic anisotropy, but the magnetic anisotropy is reduced due to a slight change in the alloy composition or manufacturing conditions. And it is difficult to stably obtain excellent magnetic anisotropy.

(2) As means for imparting magnetic anisotropy, generally R
Means for flattening the crystal grains of the R-Fe-Co-B permanent magnet powder by subjecting the Fe-Co-B permanent magnet powder to hot plastic working such as hot rolling and hot extrusion are known. Even if the hot plastic working is applied to the R-Fe-Co-B-based permanent magnet powder having the recrystallized structure, the magnetic anisotropy is improved,
The hot plastic working inevitably causes a variation in the working ratio depending on the place, and it is not possible to obtain a stable and uniform R-Fe-Co-B permanent magnet powder having excellent magnetic anisotropy. In addition, the manufacturing process is complicated and costly.

(3) When the recrystallized grains are flattened by the hot plastic working, the flattened R-Fe-Co-B-based permanent magnet powder becomes
The R-Fe-Co-B permanent magnet powder is more easily corroded than the recrystallized R-Fe-Co-B permanent magnet powder, and when this R-Fe-Co-B permanent magnet powder is stored for a long time in a high-temperature and high-humidity environment such as a factory, R
-The surface of the Fe-Co-B-based permanent magnet powder is corroded, and the magnetic properties are degraded.

And so on.

[Means for solving the problem]

Thus, the present inventors conducted research to obtain a permanent magnet powder having excellent magnetic anisotropy and excellent corrosion resistance without performing the hot plastic working, and as a result, (1) Ga, Zr, Total amount of one or more of Hr:
An R- having a recrystallized texture in which recrystallized grains containing an R ₂ (Fe, Co) ₁₄ B-type phase as a main phase containing 0.001 to 5.0% (% indicates atomic%, hereinafter% indicates atomic%) The Fe-Co-B-based permanent magnet powder exhibits excellent magnetic anisotropy without being subjected to hot plastic working. (2) The shortest particle size of each recrystallized grain constituting the recrystallized texture is determined by a, where the longest particle size is b, R-Fe-Co-B permanent magnet powder having a recrystallized texture composed of recrystallized grains having a shape satisfying b / a <2 has excellent corrosion resistance. And other findings.

The present invention has been made based on such findings, and (a) R-Fe-Co- containing R, Fe, Co and B as main components.
The individual powders of the B-based permanent magnet powder are: R: 10 to 20%, Co: 0.1 to 50%, B: 3 to 20%, Total of one or more of Ga, Zr and Hf: 0.00
And a composition in which the ratio b / a of the shortest particle size a to the longest particle size b of each recrystallized grain is less than 2 and the balance is Fe and unavoidable impurities. Recrystallized particle size is 0.05-20
R ₂ (Fe, Co) with μm size and tetragonal structure
₁₄ Recrystallized texture in which recrystallized grains mainly composed of B-type intermetallic compound phase are adjacent to each other, and rare earth-Fe with excellent magnetic anisotropy and corrosion resistance
-Co-B permanent magnet powder, (b) R-Fe-Co containing R, Fe, Co and B as main components
The individual powders of the B-based permanent magnet powder are as follows: R: 10 to 20%, Co: 0.1 to 50%, B: 3 to 20%, total of one or more of Ga, Zr and Hf: 0.00
1 to 5.0%, and a total of one or more of Al, V and Si: 0.01
2.02.0%, the balance being Fe and unavoidable impurities, and the shape and average recrystallization in which the ratio b / a of the shortest particle size a to the longest particle size b of each recrystallized grain is less than 2. Particle size 0.05-20
R ₂ (Fe, Co) with μm size and tetragonal structure
₁₄ Recrystallized texture in which recrystallized grains mainly composed of B-type intermetallic compound phase are adjacent to each other;
-Co-B-based permanent magnet powder; and (c) the rare earth -Fe-Co-B of (a) and (b) above.
And a bonded magnet manufactured from a system-based permanent magnet powder.

R-Fe excellent in magnetic anisotropy and corrosion resistance of the present invention
-Co-B-based permanent magnet powder is an R-Fe-Co-B-based master alloy containing one or more of Ga, Zr, and Hf by melting and casting so as to have a predetermined component composition; An R-Fe-Co-B-based master alloy containing one or more of Al, V, and Si so as to have a predetermined component composition is further produced in the alloy, and this R-Fe-Co-B The system mother alloy is heated in a hydrogen gas atmosphere, and heat-treated in a hydrogen gas atmosphere or a mixed gas atmosphere of a hydrogen gas and an inert gas at a temperature of 500 to 1000 ° C., and then a temperature of 500 to 1000 ° C. It is manufactured by performing dehydrogenation treatment until the gas pressure becomes 1 Torr or less vacuum atmosphere or hydrogen gas partial pressure: 1 Torr or less inert gas atmosphere, and then cooling.

A step of homogenizing an R-Fe-Co-B-based master alloy containing a predetermined amount of one or more of Ga, Zr, and Hf at a temperature of 600 to 1200 ° C and a temperature after the dehydrogenation treatment : 300
R-Fe-Co-B having better magnetic anisotropy and corrosion resistance by adding a heat treatment step at ~ 1000 ° C
-Based permanent magnet powder can be manufactured.

An R-Fe-Co-B-based master alloy containing a predetermined amount of one or more of Ga, Zr, and Hf, and a predetermined amount of one or more of Al, V, and Si. Temperature: R-Fe-Co-B-based permanent magnet powder obtained by adding a step of homogenizing at 600 to 1200 ° C and a step of heat treating at a temperature of 300 to 1000 ° C after the dehydrogenation treatment, In addition to good magnetic anisotropy and corrosion resistance, it has a better maximum energy product.

The R-Fe-Co-B of the present invention thus produced
The structure of the permanent magnet powder is composed of a recrystallized texture in which recrystallized grains of the R ₂ (Fe, Co) ₁₄ B type intermetallic compound phase are free from impurities and strains in the grains and grain boundaries. .

It is sufficient that the average recrystallized grain constituting the recrystallized texture is in the range of 0.05 to 20 μm, but in the range of 0.05 to 3 μm which is close to the size of the single magnetic domain grain size (about 0.3 μm). Is more preferable.

The individual recrystallized grains having the above dimensions preferably have a shape in which the ratio of the shortest particle size a to the longest particle size b is b / a <2. It must be present at 50% by volume or more. By having a recrystallized grain shape in which the ratio b / a of the shortest particle diameter a to the longest particle diameter b is smaller than 2, the coercive force of the R-Fe-Co-B-based permanent magnet powder is improved and the corrosion resistance is also improved. R-Fe-Co with improved magnetic anisotropy obtained by performing conventional hot plastic working
-It is superior in corrosion resistance to B-based permanent magnet powder, has no variation in magnetic anisotropy, and can obtain excellent magnetic properties stably with good yield.

Further, the R-Fe of the present invention thus produced
-The recrystallization texture of the Co-B-based permanent magnet powder is substantially
Since the recrystallized grains composed of the R ₂ (Fe, Co) ₁₄ B-type intermetallic compound phase are adjacent to each other, the magnetization value can be increased by the absence of the grain boundary phase, and also through the grain boundary phase. It is considered that the corrosion is prevented from progressing, and since there is no stress distortion due to hot plastic working, the possibility of stress corrosion is small and the corrosion resistance is improved.

Therefore, a bonded magnet manufactured using the R-Fe-Co-B-based permanent magnet powder of the present invention having excellent magnetic anisotropy and corrosion resistance also has excellent magnetic anisotropy and corrosion resistance. .

Next, the reason why the component composition and the average recrystallized grain size of the R-Fe-Co-B-based permanent magnet powder having excellent corrosion resistance, magnetic anisotropy and corrosion resistance of the present invention are limited as described above will be described.

(A) R R is Nd, Pr, Tb, Dy, La, Ce, Ho, Er, Eu, Sm, Gd, Tm, Yb, Lu
And one or more of Y, which is generally composed mainly of Nd, and used by adding other rare earth elements thereto. Particularly, Tb, Dy and Pr have an effect of improving the coercive force iHc, If the R content is lower than 10% or higher than 20%, the coercive force of the permanent magnet powder decreases, and excellent magnetic properties cannot be obtained. Therefore, the content of R is 10-20%
Determined.

(B) BB If the B content is lower than 3% or higher than 20%, the coercive force of the permanent magnet powder is reduced, and excellent magnetic properties cannot be obtained. %. A part of B may be replaced with C, N, O, or F.

(C) Co By adding Co, the coercive force and magnetic temperature characteristics (for example, Curie point) of the permanent magnet powder are improved, and there is an effect of further improving the corrosion resistance.
If the content is less than 50%, the desired effect cannot be obtained. On the other hand, if the content exceeds 50%, the magnetic properties are rather deteriorated. Therefore, the content of Co is set to 0.1 to 50%. Co
Is more preferably 0.1 to 20% since the coercive force becomes highest when the content is 0.1 to 20%.

(D) Ga, Zr and Hf These components are contained as components of the R-Fe-Co-B-based permanent magnet powder to improve coercive force and stably impart excellent magnetic anisotropy and corrosion resistance. However, if the content is less than 0.001%, the desired effect cannot be obtained, while if the content exceeds 5.0%, the magnetic properties deteriorate. Therefore, one or two of Ga, Zr and Hf
The total number of species is set to 0.001 to 5.0%.

(E) Al, V and Si One or more of Ga, Zr and Hf: R, Fe and Co based permanent magnet alloys containing 0.001 to 5.0%,
The maximum energy product can be stably increased by adding one or more of the above, but if the content is less than 0.01%, the desired effect cannot be obtained.
% Is not preferable because the value of magnetization cannot be increased.

Therefore, one or more of Al, V and Si are set to 0.01 to 2.0% in total.

(F) Average recrystallized grain size The average recrystallized grain size of the R ₂ (Fe, Co) ₁₄ B type phase recrystallized grains constituting each powder structure of the R-Fe-Co-B-based permanent magnet powder is 0.05. If it is smaller than μm, magnetization becomes difficult, which is not preferable. On the other hand, if it is larger than 20 μm, coercive force and squareness decrease, and high magnetic properties cannot be obtained, which is not preferable.

Therefore, the average recrystallized grain size is set to 0.05 to 20 μm. In this case, the average recrystallized grain size is the size of the single magnetic domain grain size (0.
It is more preferable that the thickness is 0.05 to 3 μm, which is close to 3 μm).

As described above, the R-Fe-Co-B-based permanent magnet powder has been described. The reason for the limitation is that the R-Fe-Co-B-based bonded magnet manufactured from the R-Fe-Co-B-based permanent magnet powder is used. That is also true.

〔Example〕

The present invention will be specifically described based on examples and comparative examples.

Examples 1 to 36, Comparative Examples 1 to 10, and Conventional Examples 1 to 2 Co shown in Table 1 obtained by plasma melting and casting.
And R-Fe-Co-B-based alloy ingots containing one or more of Ga, Zr and Hf;
An R-Fe-Co-B based alloy ingot containing no r and Hf was prepared, and these alloy ingots were each homogenized in an argon gas atmosphere at a temperature of 1120 ° C. for 40 hours. Approximately 20mm
The raw material alloy was crushed to the corner. This raw material alloy was heated from room temperature to 850 ° C. in a hydrogen atmosphere at 1 atm, and subjected to a heat treatment in a hydrogen atmosphere maintained at 850 ° C. for 4 hours.
After performing dehydrogenation until the degree of vacuum becomes 1 × 10 ^-1 Torr or less,
Immediately, argon gas was introduced to quench the mixture.

The obtained raw material alloy was lightly pulverized in a mortar, and average particle size: 3
Magnet powders of Examples 1 to 36, Comparative Examples 1 to 10 and Conventional Example 1 having 0 μm were obtained. Further, a part of the raw material alloy which had been subjected to the hydrogen treatment of the above-mentioned conventional example 1 was further heated at 660 ° C. and 1 × 10 ⁻³ Torr.
Hot pressing to a density of 98% in a vacuum of
After plastic working to a height of 1/4 at 0 ° C., the bulk was pulverized so as to have an average particle size of 30 μm to obtain a magnet powder of Conventional Example 2. The average recrystallized grain size, the shortest grain size a and the longest grain size of the R-Fe-Co-B-based permanent magnet powders of Examples 1 to 36, Comparative Examples 1 to 10 and Conventional Examples 1 and 2 thus obtained. After measuring the abundance (volume%) of the recrystallized grains satisfying the ratio b / a <2 of the diameter b, these R-Fe-Co-B permanent magnet powders are sieved to obtain a particle diameter of 50 to 420 μm. 100g each of these powders, temperature: 80 ° C, humidity 9
A wet test was carried out by leaving the sample in a 5% atmosphere, and the weight change due to oxidation of the powder after 1000 hours was measured. The results are shown in Table 1 in terms of the weight change rate (% by weight).

On the other hand, the magnet powder obtained in Example 25 in Table 1, which is a typical magnet powder of the R-Fe-Co-B-based permanent magnet powder of the present invention, was observed with a transmission electron microscope, and was observed with a transmission electron microscope. The photograph of the structure is shown in FIG. From the bright field image of the magnet powder of FIG. 1, the magnet powder, uniformly average recrystallized grain size: 0.3 [mu] m of _{R 2 (Fe, Co) 14} B intermetallic phase is present, recrystallization The ratio of the shortest particle size a to the longest particle size b of the grains b / a <2
That the recrystallized grains having the shape of (a) are present at about 90% by volume of the total recrystallized grains, and that no grain boundary phase exists between the individual recrystallized grains;
It can be seen visually that the recrystallized grains of the R ₂ (Fe, Co) ₁₄ B intermetallic compound phase have adjacent recrystallized textures.

As described above, the average recrystallized grain size, the ratio of the recrystallized grains having the shape of b / a <2 were measured, and observed with a transmission electron microscope. Each of the R-Fe-Co-B permanent magnet powders obtained in Conventional Examples 1 and 2 was mixed with 3.0% by weight of an epoxy resin to obtain 25KOe.
Horizontal magnet During or without a magnetic field fly pressure: then pressed at 6 ton / cm ^2,
Then, a thermosetting treatment of holding at a temperature of 120 ° C. for 2 hours was performed to produce bonded magnets of Examples 1 to 36, Comparative Examples 1 to 10, and Conventional Examples 1 and 2.

The magnetic properties of the bonded magnet obtained by press-molding in a horizontal magnetic field and the bonded magnet obtained by press-forming in a non-magnetic field were measured and shown in Table 1, and their magnetic properties were compared. Was evaluated for magnetic anisotropy.

From the results in Table 1, (1) the bonded magnets obtained by press-molding the R-Fe-Co-B-based permanent magnet powders of Examples 1 to 36 of the present invention in a horizontal magnetic field were press-formed in a non-magnetic field. Since the magnetic properties, particularly the maximum energy product (BH) _max and the residual magnetic flux density Br, are superior to those of the bonded magnets obtained in Example 1, the R-Fe-Co-B-based permanent magnets of Examples 1 to 36 of the present invention were used. The magnet powder is an R-Fe-Co-B-based permanent magnet powder having excellent magnetic anisotropy. However, the R-Fe- of Comparative Examples 1 to 10 having values (values marked with * in Table 1) out of the conditions of the present invention.
Bond magnet made using Co-B permanent magnet powder,
It has low magnetic anisotropy and extremely low magnetic properties.

(2) R-Fe-Co- of Conventional Example 1 without addition of Ga, Zr and Hf
The B-based permanent magnet powder has insufficient magnetic anisotropy and is inferior in corrosion resistance even under the same manufacturing conditions as in Examples 1 to 36. The recrystallized grains are flattened by plastic working, and about 40% of the recrystallized grains having a ratio b / a <2 of the shortest grain size a and the longest grain size b of the recrystallized grains (ie, hot working) According to the R-Fe-Co-B permanent magnet powder of Conventional Example 2, the crystal grains having a flat shape of b / a ≧ 2 account for about 60% of the total crystal grains,
Although the magnetic anisotropy is not inferior to that of the R-Fe-Co-B permanent magnet powder of No. 36, the corrosion resistance is greatly reduced because the weight change rate by the wet test is large.

Examples 37 to 46 and Comparative Examples 11 to 13 An R-Fe-Co-B-based alloy containing one or more of Ga, Zr and Hf obtained by plasma melting and casting was further added with Al, V , Si, and prepared various alloy ingots having the composition shown in Table 2 containing one or more of Si. These ingots were prepared in Examples 1 to 36 and Comparative Examples 1 to 3.
R-Fe-Co having an average particle diameter of 30 μm in Examples 37 to 46 and Comparative Examples 11 to 13 under the same conditions as in Example 10 and Conventional Example 1.
After producing a B-type permanent magnet powder and measuring the ratio b / a of the shortest particle size a to the longest particle size b of the recrystallized grains, the weight change rate (% by weight) by a wet test under the same conditions as above. Were measured, then the bonded magnets were manufactured, and the magnetic properties of the bonded magnets obtained by press molding in a transverse magnetic field and the bonded magnets obtained by press molding in a non-magnetic field were measured. The results are shown in Table 2. It was shown to.

From the results in Table 2, one or more of Ga, Zr, and Hf: 0.001 to 5.0%, and one or more of Al, V, and Si are added by 0.01 to 2.0%. Maximum energy product is further improved, showing more pronounced magnetic anisotropy You can see that

[Effects of the Invention] The present invention provides one or two of Ga, Zr, and Hf together with Co.
It is possible to obtain hot H ₂ treatment alone showed marked magnetic anisotropy and R-Fe-Co-B based permanent magnet powder excellent in corrosion resistance without performing the plastic working by incorporating more species Therefore, there is an effect that there is no need to perform a magnetic anisotropy means such as hot plastic working as in the related art.

[Brief description of the drawings]

FIG. 1 is a metallographic photograph of the R-Fe-Co-B-based permanent magnet powder of the present invention taken by a transmission electron microscope.

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Claims (4)

(57) [Claims] An R-Fe- containing at least one of the rare earth elements containing Y (hereinafter referred to as R), Fe, Co and B as main components.
The individual powders of the Co-B permanent magnet powder are, in atomic percentage, R: 10 to 20%, Co: 0.1 to 50%, B: 3 to 20%, one or two of Ga, Zr and Hf. Total above: 0.001
And a recrystallization grain whose main phase is an R ₂ (Fe, Co) ₁₄ B-type intermetallic compound phase having a tetragonal structure. The recrystallized texture has a ratio of the shortest particle diameter a to the longest particle diameter b of each recrystallized grain b / a of less than 2, and the recrystallized grains are all recrystallized. The average recrystallized grain size of the recrystallized grains present in 50% by volume or more of the crystal grains and constituting the recrystallized texture is 0.05 to 20
A rare earth-Fe-Co-B permanent magnet powder having a size of μm and having excellent magnetic anisotropy and corrosion resistance. 2. R-Fe-Co containing R, Fe, Co and B as main components.
The individual powder of the B-based permanent magnet powder is, in atomic percentage, R: 10 to 20%, Co: 0.1 to 50%, B: 3 to 20%, one or more of Ga, Zr and Hf Total: 0.001
-5%, and a total of one or more of Al, V and Si: 0.01 to
2. The rare earth-Fe-Co-B permanent magnet powder according to claim 1, wherein the rare earth-Fe-Co-B permanent magnet powder has excellent magnetic anisotropy and corrosion resistance. 3. The average recrystallized particle size is preferably 0.05%.
3. The rare earth element having excellent magnetic anisotropy and corrosion resistance according to claim 1 or 2,
B-based permanent magnet powder. 4. A rare earth-Fe-Co made from the rare earth-Fe-Co-B-based permanent magnet powder having excellent magnetic anisotropy and corrosion resistance according to claim 1, 2 or 3. -B
System bonded magnet.