JP2586198B2 - Rare earth-Fe-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 relates to R having excellent magnetic properties, particularly excellent magnetic anisotropy and corrosion resistance (where R is at least one of the rare earth elements including Y). The present invention relates to one type) -Fe-B-based permanent magnet powder and a bonded magnet produced using the R-Fe-B-based 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 in the production of the above-mentioned bonded magnet is disclosed in Japanese Patent Application Laid-Open No. 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 promoting phase transformation to each phase of e ₂ B and the balance of Fe, H _{2 is} removed in the H ₂ removal process.
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.

[Problems to be solved by the invention]

The conventional R-Fe-B-based permanent magnet powder having a recrystallized texture described above has the following characteristics. (1) Although it has magnetic isomerism, magnetic anisotropy may be reduced due to slight fluctuations in alloy composition and manufacturing conditions. Yes,
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-B-based permanent magnet powder by subjecting the Fe-B-based permanent magnet powder to hot rolling, hot extrusion or other hot plastic working is known. Although the magnetic anisotropy is improved by applying hot plastic working to the R-Fe-B-based permanent magnet powder having the recrystallized texture, the hot plastic working causes variation in the working ratio depending on the location. Is inevitable, and R-
Not only is it impossible to obtain Fe-B-based permanent magnet powder, but also the manufacturing process becomes complicated and costs increase.

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

And so on.

[Means for solving the problem]

Therefore, the present inventors have conducted research to produce an R-Fe-B-based permanent magnet powder having a recrystallized texture having stable and excellent magnetic anisotropy without performing the hot plastic working. As a result, (a) a total amount of one or more of Ti, V, Nb, Ta, Al, and Si: 0.001 to 5.0% (% represents atomic%, and the following% represents atomic%). R-Fe-B permanent magnet powder having a recrystallized texture having ₂ Fe ₁₄ B type phase as a main phase exhibits excellent magnetic anisotropy without performing hot plastic working, and excellent corrosion resistance Also shown.

(B) Assuming that the shortest grain size of each recrystallized grain constituting the recrystallized texture is a and the longest grain size is b, recrystallized grains having a shape such that b / a <2 are adjacent to each other. The R-Fe-B-based permanent magnet powder having a texture is more excellent in corrosion resistance.

The knowledge was obtained.

The present invention has been made based on such findings, and (1) each of the R-Fe-B-based permanent magnet powders contains: R: 10 to 20%, and B: 3 to 20%. And the total amount of one or more of Ti, V, Nb, Ta, Al and Si: 0.001 to 5.0%, the balance being Fe and unavoidable impurities, and the average recrystallized grain size: R ₂ Fe ₁₄ B type metal having a size of 0.05 to 20 μm and a shape in which the value of the ratio b / a of the shortest particle diameter a to the longest particle diameter b of each recrystallized grain is smaller than 2 and having a tetragonal structure R-Fe-B having excellent magnetic anisotropy and corrosion resistance consisting of:
-Based permanent magnet powder, (2) R-Fe having excellent magnetic anisotropy and corrosion resistance
-A bonded magnet manufactured using a B-based permanent magnet powder.

R-Fe excellent in magnetic anisotropy and corrosion resistance of the present invention
-B-based permanent magnet powder is melt-cast to produce an R-Fe-B-based mother alloy having a predetermined component composition containing one or more of Ti, V, Nb, Ta, Al and Si. And this R-Fe
-The temperature of the B-based master alloy is raised in a hydrogen gas atmosphere,
Heat treatment at 1000 ° C. in a hydrogen gas atmosphere or a mixed atmosphere of hydrogen gas and an inert gas, then temperature: 500 to 1000
C., hydrogen gas pressure: 1 Torr or less, or hydrogen gas partial pressure: 1 Torr or less.

Step of homogenizing the R-Fe-B-based master alloy at a temperature of 600 to 1200 ° C and performing the dehydrogenation treatment, and then the temperature: 300 to
By adding a heat treatment at 1000 ° C., an R—Fe—B permanent magnet powder having more excellent magnetic anisotropy and corrosion resistance can be produced.

The structure of the R-Fe-B-based permanent magnet powder of the present invention produced in this manner is such that the recrystallized grains of the R ₂ Fe ₁₄ B type intermetallic compound phase have no impurities or strains in the grains and grain boundaries. Are composed of adjacent recrystallized textures. The average recrystallized grain size of the recrystallized grains constituting this recrystallized texture is sufficient if it is in the range of 0.05 to 20 μm.
More preferably, it is in the range of 0.05 to 3 μm close to 3 μm). 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 in at least 50% by volume of all recrystallized grains. The ratio b / a of the shortest particle diameter a to the longest particle diameter b has a shape of recrystallized grains smaller than 2, thereby improving the coercive force of the R-Fe-B-based permanent magnet powder and improving the corrosion resistance, It has better corrosion resistance than R-Fe-B permanent magnet powder with magnetic anisotropy obtained by performing conventional hot plastic working, has no variation in magnetic anisotropy, and has excellent yield and stability. Magnetic properties can be obtained.

Further, the R-Fe of the present invention thus produced
-The recrystallized structure of the B-based permanent magnet powder has a recrystallized texture substantially composed only of the R ₂ Fe ₁₄ B type intermetallic compound phase in which almost no grain boundary phase is present. The value of magnetization can be increased by the absence of the field phase,
It is considered that corrosion that progresses through the grain boundary phase is suppressed, and since there is no stress strain due to hot plastic working, the possibility of stress corrosion is small and the corrosion resistance is improved.

Therefore, the bonded magnet manufactured using the R-Fe-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, R- according to the present invention, which is excellent in magnetic anisotropic corrosion resistance, is used.
The reason why the component composition and the average recrystallized particle size of the Fe-B-based permanent magnet powder 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 elements of Y, and generally contains Nd as a main component, and is used by adding other rare earth elements. Particularly, Tb, Dy, and Pr have an effect of improving the coercive force iHc. Yes, even if the content of R is lower than 10%,
Even if it is 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
It was set to 10-20%.

(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. %. Also, B
May be substituted with one or two of N, P, F and C.

(C) Ti, V, Nb, Ta, Al and Si Ti, V, Nb, Ta, Al and
Si is contained as a component of the R-Fe-B-based permanent magnet powder,
It has the effect of improving coercive force and stably giving excellent magnetic anisotropy and corrosion resistance.
The total content of one or more of a, Al and Si
If it is less than 0.001%, the desired effect cannot be obtained, while if it exceeds 5.0%, the magnetic properties deteriorate. Therefore, T
The total content of one or more of i, V, Nb, Ta, Al, and Si is set to 0.001 to 5.0%.

Even if at least one of Co, Ni, Cu, Zn, Ga, Ge, Zr, Mo, Hf, and W is contained in an amount of 0.001 to 5.0%, R-Fe having excellent magnetic anisotropy and corrosion resistance can be obtained. -B type permanent magnet powder is obtained.

(D) Average recrystallized grain size If the average recrystallized grain size of the recrystallized grains constituting each powder structure of the R-Fe-B-based permanent magnet powder is smaller than 0.05 μm, magnetization becomes difficult, which is not preferable. On the other hand, if it is larger than 20 μm, the coercive force and the 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 0.05
３3 μm is more preferred.

As described above, the R-Fe-B-based permanent magnet powder has been described.
The reason for the limitation is not limited to the R-Fe-B-based permanent magnet powder, but is also applicable to an R-Fe-B-based bonded magnet manufactured from the R-Fe-B-based permanent magnet powder. .

〔Example〕

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

Examples 1-46, Comparative Examples 1-14 and Conventional Examples 1-2 T shown in Table 1 obtained by plasma melting and casting.
Various alloy ingots containing one or more of i, V, Nb, Ta, Al and Si, and alloy ingots not containing any of the above Ti, V, Nb, Ta, Al, Si are each placed in an agon gas atmosphere. After homogenizing at a temperature of 1140 ° C. and holding for 20 hours, this homogenized ingot was crushed to about 20 mm square to obtain a raw material alloy. This raw material alloy is heated from room temperature to 840 ° C. in a hydrogen atmosphere at 1 atm, and is subjected to a heat treatment in a hydrogen atmosphere maintained at 840 ° C. for 4 hours.
After dehydrogenation to 0 ^-1 Torr or less, the mixture was immediately cooled by flowing argon gas. After the completion of the hydrogen treatment, a heat treatment at 650 ° C. was performed in an argon gas. The obtained raw material alloy was lightly powdered in a mortar to obtain magnet powders of Examples 1 to 46, Comparative Examples 1 to 14 and Conventional Example 1 having an average particle size of 40 μm. Further, a part of the raw material alloy after the hydrogen treatment in Conventional Example 1 was further hot-pressed to a density ratio of 98% in a vacuum of 680 ° C. and 1 × 10 ⁻³ Torr. After plastic working to / 4, this bulk is averaged in particle size:
The powder was pulverized to 40 μm to obtain Conventional Example 2 magnet powder. The average recrystallized particle size and the longest particle size / the shortest particle size of the R-Fe-B-based permanent magnet powders of Examples 1 to 46, Comparative Examples 1 to 14, and Conventional Examples 1 and 2 obtained as described above are as follows. After measuring the abundance (volume%) of recrystallized grains smaller than 2, these R-Fe-B-based permanent magnet powders were sieved to obtain 50-42.
A powder having a particle size between 0 μm was prepared, 100 g of each of these powders was taken, and left as it was in an atmosphere at a temperature of 80 ° C. and a humidity of 95% to perform a wet test. Change in weight due to weight change (weight%)
The results are shown in Table 1.

Examples 1-46, Comparative Examples 1-14 and Conventional Examples 1-2
R-Fe-B-based permanent magnet powder is mixed with 3.0% by weight of epoxy resin, and in a transverse magnetic field of 25 KOe or in a non-magnetic field, pressure: 6T
Press molding at on / cm ² , and then subjected to a thermosetting treatment at a temperature of 120 ° C. for 2 hours to produce the bonded magnets of Examples 1 to 46, Comparative Examples 1 to 14 and Conventional Examples 1 to 2, In a transverse magnetic field The magnetic properties of the bond magnet obtained by press molding and the bond magnet obtained by press molding in the absence of a magnetic field were measured, and the magnetic properties were compared to evaluate the magnetic anisotropy.

From the results in Table 1, it can be seen that Ti, V, Nb, Ta, Al and S
Bond magnets obtained by press-molding an R-Fe-B-based permanent magnet powder containing one or more of i in a horizontal magnetic field in Examples 1 to 46 are obtained by press-molding in a non-magnetic field. Magnetic properties, especially the maximum energy product (BH) compared to bonded magnets
_It can be seen that the R-Fe-B-based permanent magnet powder having excellent _max and residual magnetic flux density Br and excellent magnetic anisotropy was obtained. However, as shown in Comparative Examples 1 to 14, when the content of one or more of Ti, V, Nb, Ta, Al and Si deviates from the conditions of the present invention, the magnetic anisotropy decreases. However, when the average recrystallized grain system or R and B deviate from the conditions of the present invention (in Table 1, the values deviating from the conditions of the present invention are marked with *), the magnetic properties are reduced. As can be seen in Example 1, those containing none of Ti, V, Nb, Ta, Al, and Si do not show sufficient magnetic anisotropy under the same manufacturing conditions and have poor corrosion resistance. Further, in order to impart magnetic anisotropy, hot plastic working is performed to make the recrystallized grains flat, and the recrystallized grains have a value of (longest particle diameter / shortest particle diameter) of 2
The R-Fe-B permanent magnet powder of Conventional Example 2 in which less than about 40% by volume of recrystallized grains are present is smaller than Ti, V, Nb,
R-Fe- containing one or more of Ta, Al and Si
The magnetic anisotropy is not particularly inferior to B-based permanent magnet powder, but the weight change rate by the wet test is large,
It can also be seen that the corrosion resistance has decreased.

〔The invention's effect〕

The present invention, Ti, V, Nb, Ta , Al, by incorporating one or more of Si, R-Fe- showing significant magnetic anisotropy and corrosion resistance by H ₂ treatment A B-based permanent magnet powder can be obtained, so that there is no need to perform magnetic anisotropic means such as hot plastic working as in the related art, and there is an effect that the manufacturing cost can be greatly reduced.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-64-45103 (JP, A) JP-A-63-232301 (JP, A) JP-A-1-103805 (JP, A) JP-A-59-103 222564 (JP, A)

Claims (3)

(57) [Claims] At least one of the rare earth elements containing Y (hereinafter referred to as R) and each of R-Fe-B permanent magnet powders containing Fe and B as main components are represented by the following formula: 10 to 20%, B: 3 to 20%, total of one or more of Ti, V, Nb, Ta, Al and Si: 0.001 to 5.0%, with the balance being Fe and unavoidable impurities And a recrystallized texture in which a recrystallized grain whose main phase is an R ₂ Fe ₁₄ type intermetallic compound having a production crystal structure has an adjacent recrystallized texture. The recrystallized grains having a ratio of b / a of the shortest particle diameter a to the longest particle diameter b at two terminals are present at 50% by volume or more of all recrystallized grains, and the recrystallized grains constituting the recrystallized texture The average recrystallized grain size of the grains is 0.05-20
A rare earth-Fe-B-based permanent magnet powder excellent in magnetic anisotropy and corrosion resistance, having a size of μm. 2. The rare-earth-Fe-B permanent magnet powder according to claim 1, wherein said average recrystallized grain size is 0.05 to 3 μm. 3. A bonded rare earth-Fe-B magnet made from the rare earth-Fe-B permanent magnet powder according to claim 1 or 2 having excellent magnetic anisotropy and corrosion resistance.