JP3196224B2 - Rare earth-Fe-Co-B anisotropic magnet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to at least one of the rare earth elements containing Y (hereinafter, referred to as R) having excellent magnetic properties and a small temperature coefficient of coercive force, Fe, Co, and B.
The present invention relates to an R-Fe-Co-B-based anisotropic magnet mainly composed of: More specifically, R formed of a hot press or hot isostatic press (hereinafter referred to as HIP) formed body
-Fe-Co-B based anisotropic magnet.

[0002]

2. Description of the Related Art Japanese Patent Laid-Open Publication No.
-Fe-Co-B-based permanent magnet powder is described, and this R-Fe-Co-B-based permanent magnet powder has a ferromagnetic phase of R ₂ (Fe, Co) ₁₄ B type intermetallic compound phase. the R-Fe-Co-B-based master alloy, a main phase as a raw material, RH by heat-treating the mother alloy material in an H ₂ atmosphere in a predetermined temperature range
_x and (Fe, Co) after prompting the phase transformation to each phase of the ₂ B and the balance Fe, the process of removing of H ₂ with deionized H ₂ steps from the raw material (hereinafter
This process is hereinafter referred to as an HDDR process) to produce an R ₂ (Fe, Co) ₁₄ B-type phase which is a ferromagnetic phase again, and the resulting R-Fe-Co-B system is obtained. organization of the permanent magnet powder has an average particle size: very fine R ₂ of 0.05 to 3 [mu] m (Fe, Co) a recrystallized structure of ₁₄ B type phase has a recrystallized texture whose main phase.

The R-Fe-Co-B-based permanent magnet powder cannot be sufficiently hot-pressed into a hot-pressed compact to obtain sufficient magnetic anisotropy.
As described in JP-A-39503, the hot-pressed product is further subjected to hot rolling such as hot rolling to orient the C-axis of the recrystallized grains of the R ₂ (Fe, Co) ₁₄ B phase. The magnetic anisotropy was improved by using a reduced rolling structure.

[0004]

However, the R-F obtained by hot-rolling the above hot-pressed body is further used.
Although the e-Co-B rolled magnet has excellent magnetic anisotropy, the temperature coefficient of the coercive force increases, and this R-Fe-C
When the oB rolled magnet is incorporated in a motor or the like, there is a problem that the performance of the motor or the like changes due to a change in temperature, and the stability is lacking.

[0005] Further, R-Fe-Co-B-based rolled magnets are:
Variations in the working ratio depending on the location lead to variations in the magnetic anisotropy, and in order to prevent this, the process of hot plastic working had to be complicated.

[0006]

Means for Solving the Problems Accordingly, the present inventors have
Since the increase in the temperature coefficient of the coercive force is caused by hot-rolling a hot-pressed product, if a magnet having excellent magnetic anisotropy can be obtained without performing the hot-rolling, As a result of conducting research based on the recognition that the temperature coefficient of coercive force does not increase, R: 10 to 20%, Co: 0.1 to 50%, B: 3 to 20%, Ti, V, Total of one or more of Ta: 0.
001-5.0%, the balance being Fe and inevitable impurities, and 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 have an average recrystallized particle size of 0.05 to 20 μm, and
R ₂ (F) having a tetragonal structure obtained by HDDR treatment
e, Co) ₁₄ B-type intermetallic compound phase as a main phase. It has been found that Fe-Co-B-based magnets reduce the temperature coefficient of coercive force while maintaining excellent magnetic anisotropy.

The present invention has been made based on this finding. (1) At least one of the rare earth elements containing Y (hereinafter, referred to as R) and R, which contains Fe, Co, and B as main components, -F
This is an e-Co-B based anisotropic magnet, wherein the anisotropic magnet is, in atomic percentage, R: 10 to 20%, Co: 0.1 to 50%, B: 3 to 20%, Ti, Total of one or more of V and Ta: 0.
001-5.0%, with the balance being Fe and unavoidable impurities, and an R ₂ (Fe, Co) ₁₄ B type intermetallic compound phase having a tetragonal structure obtained by HDDR treatment. A recrystallized grain texture in which recrystallized grains as phases are assembled adjacent to each other, and the recrystallized grain texture has a ratio b between the shortest grain size a and the longest grain size b of each recrystallized grain. / A value is 2
The recrystallized grains having a shape less than 50% by volume of all recrystallized grains are present, and the average recrystallized grain size of the recrystallized grains constituting the recrystallized grain texture has a size of 0.05 to 20 μm. R-Fe-Co-B-based anisotropic magnet which is a hot-press molded body, (2) R-Fe-C containing R, Fe, Co and B as main components
This is an OB-based anisotropic magnet, wherein the anisotropic magnet has an atomic percentage of R: 10 to 20%, Co: 0.1 to 50%, B: 3 to 20%, Ti, V, Total of one or more of Ta: 0.
001-5.0%, with the balance being Fe and unavoidable impurities, and an R ₂ (Fe, Co) ₁₄ B type intermetallic compound phase having a tetragonal structure obtained by HDDR treatment. A recrystallized grain texture in which recrystallized grains as phases are assembled adjacent to each other, and the recrystallized grain texture has a ratio b between the shortest grain size a and the longest grain size b of each recrystallized grain. / A value is 2
The recrystallized grains having a shape less than 50% by volume of all recrystallized grains are present, and the average recrystallized grain size of the recrystallized grains constituting the recrystallized grain texture has a size of 0.05 to 20 μm. An R-Fe-Co-B-based anisotropic magnet, which is a hot isostatic press formed body, is characterized.

According to the present invention, the temperature coefficient of the coercive force of R-
The Fe-Co-B-based anisotropic magnet has little variation in magnetic anisotropy depending on the location and has excellent corrosion resistance as compared with the conventional rolled magnet.

The R-Fe- Co- B anisotropic magnet of the present invention has a recrystallized grain texture,
₂ (Fe, Co) ₁₄ B-type compound composition vicinity, that is, R
_11.8 (Fe , Co) _bal B Even at around _5.9 composition, it has excellent magnetic anisotropy and high coercive force.

Next, a method for producing the R-Fe-Co-B-based anisotropic magnet of the present invention will be described.

The R-Fe-Co-B-based permanent magnet powder for producing the R-Fe-Co-B-based anisotropic magnet of the present invention is prepared by melting and casting, and one or more of Ti, V and Ta or R-Fe- containing two or more kinds so as to have a predetermined component composition
A Co-B-based master alloy was manufactured, and the temperature of the R-Fe-Co-B-based master alloy was increased in a hydrogen gas atmosphere.
Heat treatment at 000 ° C. in a hydrogen gas atmosphere or a mixed gas atmosphere of hydrogen gas and an inert gas.
It is manufactured by performing dehydrogenation treatment until it becomes a vacuum atmosphere of 0 to 1000 ° C. and a hydrogen gas pressure of 1 Torr or less or an inert gas atmosphere of a hydrogen gas partial pressure of 1 Torr or less and then cooling. The temperature: 500 to 1000 ° C., hydrogen gas atmosphere
Heat in ambient air or mixed atmosphere of hydrogen gas and inert gas
RH by treating _x and (Fe, Co) ₂ B and the balance
The phase transformation of each phase of Fe is promoted.
000 ° C, hydrogen gas pressure: 1 Torr or less
Is an inert gas atmosphere of hydrogen gas partial pressure: 1 Torr or less
Dehydrogenation treatment until the ferromagnetic phase R ₂
When the (Fe, Co) ₁₄ B type phase is generated, R ₂ (Fe,
Co) ₁₄ B type phase as main phase, average particle size: 0.05-20μ
recrystallized grains having a size of m
It becomes a crystal grain texture.

A step of homogenizing an R-Fe-Co-B-based master alloy containing a predetermined amount of one or more of Ti, V, and Ta at a temperature of 600 to 1200 ° C .; Then, by adding a step of heat treatment at a temperature of 300 to 1000 ° C., an R—Fe—Co—B-based permanent magnet powder having more excellent magnetic anisotropy and corrosion resistance can be produced.

The R-Fe-Co thus produced is
-B system tissues of the permanent magnet powder is intragranular and grain boundaries R ₂ is not an impurity or strain (Fe, Co) ₁₄ recrystallization recrystallized grains of B-type intermetallic compound phase are assembled adjacent to each other It is composed of a texture.

It is sufficient if the average recrystallized grain size of the recrystallized grains constituting the recrystallized texture is in the range of 0.05 to 20 μm. More preferably, it is within the range of 0.05 to 3 μm.

Each of the recrystallized grains having the above-mentioned dimensions preferably has a shape in which the ratio of the shortest particle size a to the longest particle size b is b / a <2. It is necessary that 50% by volume or more of the crystal grains exist. 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 25 to 100
The temperature coefficient αiHc of coercive force in ° C. is -0.6% / ° C.
Smaller.

Further, the R-F thus produced is
The recrystallized texture of the e-Co-B-based permanent magnet powder is such that recrystallized grains are aggregated adjacent to each other and substantially no R ₂ (Fe, Co) ₁₄ B type metal having almost no grain boundary phase. Because it is composed only of the compound phase, the value of magnetization can be increased by the amount without the grain boundary phase, the corrosion that progresses through the grain boundary phase is suppressed, and the stress strain due to hot plastic working is also reduced. Since it does not exist, the possibility of stress corrosion is small and the corrosion resistance is improved.

The R-Fe-Co thus produced is
-B-based permanent magnet powder is molded in a magnetic field to form a green compact, and the green compact is hot-pressed or HIPed at a temperature of 600 to 900 ° C. to form the R-Fe-Co-B.
The R-Fe-Co-B anisotropic magnet of the present invention having a small coercive force temperature coefficient αiHc while maintaining the structure and characteristics of the system-based permanent magnet powder can be obtained.

The coercive force can be improved by performing a heat treatment at 300 to 1000 ° C. if necessary.

When the green compact is sintered at a normal temperature, the sintering temperature is generally high, so that R-Fe-Co-B
Fine recrystallized grains of the system-based permanent magnet powder grow and become large crystal grains, which deteriorate magnetic properties, particularly coercive force, which is not preferable.

Accordingly, the R-Fe-Co-
As a method for producing a B-based anisotropic magnet, it is necessary to adopt a hot press method or a HIP method capable of sintering at a temperature lower than a normal sintering temperature to suppress the growth of recrystallized grains. Also, since the application of magnetic anisotropy is performed by molding in a magnetic field, it is not necessary to perform hot plastic working after hot pressing and HIP.

Next, the reason why the component composition, the average recrystallized grain size and the recrystallized grains of the R-Fe-Co-B anisotropic magnet having a small coercive temperature coefficient of the present invention are limited as described above will be described. .

(A) R R is Nd, Pr, Tb, Dy, La, Ce, Ho, E
one or more of r, Eu, Sm, Gd, Tm, Yb, Lu, and Y, generally mainly Nd;
Tb, Dy, and Pr are particularly effective in improving the coercive force iHc, and may be used by adding other rare earth elements thereto, even if the R content is lower than 10% or 20%.
%, The coercive force of the anisotropic magnet decreases, and excellent magnetic properties cannot be obtained. Therefore, the content of R is 10 to
It was set to 20%.

(B) BB If the B content is lower than 3% or higher than 20%, the coercive force of the anisotropic magnet is reduced and excellent magnetic properties cannot be obtained. Was determined to be 3 to 20%. Also, B
May be replaced with C, N, O, F.

(C) Co The addition of Co improves the coercive force and magnetic temperature characteristics (eg, Curie point) of the anisotropic magnet, and further has the effect of improving corrosion resistance. .1
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 undesirably deteriorated. Therefore, the content of Co is set to 0.1 to 50%. When the content of Co is between 0.1 and 20%, the coercive force becomes highest, so that it is more preferable that the content of Co be 0.1 to 20%.

(D) Ti, V, Ta These components are contained as components of the R-Fe-Co-B-based anisotropic magnet to improve coercive force and to provide excellent magnetic anisotropy and corrosion resistance. It has a stabilizing effect, but if the content is less than 0.001%, the desired effect cannot be obtained, while if it exceeds 5.0%, the magnetic properties deteriorate. Therefore, the total of one or more of Ti, V, and Ta is set to 0.001 to 5.0%.

Further, Ni, Cu, Zn, Ga,
R-Fe-Co-B-based anisotropic magnet having excellent magnetic anisotropy and corrosion resistance even when at least one of Ge, Zr, Mo, Hf, and W is contained at 0.001 to 5.0%. Is obtained.

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

Therefore, the average recrystallized grain size is 0.05 to
It was set to 20 μm. In this case, the average recrystallized grain size is more preferably 0.05 to 3 μm which is close to the size of the single magnetic domain grain size (0.3 μm).

(F) Shape of Recrystallized Grains The shape of the recrystallized grains having the above dimensions is preferably such that the ratio b / a of the shortest particle diameter a to the longest particle diameter b is smaller than 2. Recrystallized grains have 50% of all recrystallized grains.
It must be present in a volume% or more. The above b / a <2
Is satisfied, the coercive force of the R-Fe-Co-B-based anisotropic magnet is improved, the corrosion resistance is improved, and the temperature coefficient of the coercive force is reduced.

[0030]

EXAMPLES The present invention will be specifically described based on Examples and Comparative Examples.

Co obtained by plasma melting and casting, and various R-Fe-Co-B-based alloy ingots containing one or more of Ti, V, and Ta;
R-Fe-Co containing no i, V or Ta at all
-B-based alloy ingots were prepared, and these alloy ingots were each placed in an argon gas atmosphere at a temperature of 1130 ° C.
After homogenizing under the condition of holding for 20 hours, the homogenized ingot was crushed to about 15 mm square to obtain a raw material alloy. This raw material alloy was heated from room temperature to 8 in a hydrogen atmosphere at 1 atm.
The temperature was raised to 30 ° C., heat treatment was performed in a hydrogen atmosphere maintained at 830 ° C. for 1 hour, and then 830 ° C., vacuum degree: 1 × 10
After dehydrogenation to ^-1 Torr or less, the mixture was immediately cooled by flowing argon gas. After finishing the hydrogen treatment, heat treatment was performed at 630 ° C. for 2 hours in a vacuum.

The obtained raw material alloy is lightly pulverized in a mortar,
An R-Fe-Co-B permanent magnet powder having an average particle size of 40 µm was obtained.

The R-Fe-Co-B-based permanent magnet powder is press-molded in a magnetic field of 25 KOe to produce a green compact.
1.5Ton / cm ² hot press or temperature: 710
The sintered magnets 1 to 12 of the present invention and the comparative sintered magnets 1 to 4 were manufactured by applying HIP at a temperature of 1.5 ° C. and a pressure of 1.5 Ton / cm ² , and further performing heat treatment at 620 ° C. for 2 hours under vacuum. did. The green compact formed in a magnetic field was hot-pressed by arranging the orientation direction so as to match the pressing direction in hot pressing. The densities of the obtained hot pressed bodies were all 7.5 to 7.6 g / cm ³ and were sufficiently densified.

For further comparison, R-F manufactured from an alloy ingot not containing any of Ti, V and Ta
The e-Co-B-based permanent magnet powder was filled and sealed in a copper can in a vacuum, heated to 720 ° C., and rolled several times until the rolling reduction reached 80%, to produce a conventional anisotropic magnet.

Tables 1 and 2 show the component compositions of the anisotropic magnets 1 to 12 of the present invention, comparative anisotropic magnets 1 to 4 and conventional anisotropic magnets manufactured in this manner. Average recrystallized grain size of magnet, abundance (volume%) of recrystallized grains having a value of smaller than the longest grain size / shortest grain size of individual recrystallized grains (coefficient%), coercive force temperature coefficient αiHc, and pressing in a magnetic field The magnetic properties of the R-Fe-Co-B-based anisotropic magnet obtained by subjecting the green compact obtained by hot pressing or HIP to molding were measured, and the measured values are shown in Tables 3 and 4. .

The temperature coefficient of coercive force αiHc is defined as the coercive force iHc at ₂₅ ° C. and the coercive force α at 100 ° C.
The iHc ₁₀₀ was measured, and the ratio of the coercive force difference (iHc
₁₀₀₋ iHc ₂₅ ) / iHc ₂₅ divided by a temperature difference of 75 ° C.

[0037]

[Table 1]

[0038]

[Table 2]

[0039]

[Table 3]

[0040]

[Table 4]

From the results shown in Tables 1 to 4, the Ti,
The anisotropic magnets 1 to 12 of the present invention containing one or two or more of V and Ta have almost the same magnetic properties as the conventional anisotropic magnet which is a rolled magnet not containing any of these elements. However, the temperature coefficient of the coercive force is remarkably small.
The comparative anisotropic magnets 1 to 4 in which the contents of V and Ta deviated from the conditions of the present invention have reduced magnetic anisotropy, and the size and shape of the recrystallized grains have a great influence on the magnetic properties. You can see that there is.

[0042]

According to the present invention, Ti, V, T together with Co
By using a hydrogen-treated powder containing one or two or more of a, R-Fe-Co having remarkable magnetic anisotropy without hot plastic working and having a small temperature coefficient of coercive force. -B-based magnets can be obtained, which brings about an excellent effect of improving the performance and stability of electric devices such as motors.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshinari Ishii 1-297 Kitabukurocho, Omiya City, Saitama Prefecture Mitsubishi Materials Real Co., Ltd. (72) Inventor Tamotsu Ogawa 1-2297 Kitabukurocho, Omiya City, Saitama Mitsubishi Materials Real (56) References JP-A-63-282239 (JP, A) JP-A-2-263404 (JP, A) JP-A-61-139638 (JP, A)

Claims (3)

(57) [Claims] 1. At least one of rare earth elements containing Y
An R-Fe-Co-B-based anisotropic magnet containing a seed (hereinafter referred to as R), Fe, Co, and B as main components, the anisotropic magnet having an atomic percentage of R: 10 to 10 20%, Co: 0.1 to 50%, B: 3 to 20%, Total of one or more of Ti, V, and Ta: 0.
001-5.0%, with the balance being Fe and unavoidable impurities, and RH _x and (Fe, Co) ₂ B by heat treatment in a H ₂ atmosphere.
After prompting phase transformation to each phase of the balance Fe and, H with deionized H ₂ steps
₂ from the raw material (hereinafter referred to as HDDR
R ₂ (F ) having a tetragonal structure obtained
e, Co) _14B type intermetallic compound phase as the main phase, and a recrystallized grain texture in which the recrystallized grains are aggregated adjacent to each other. Shortest particle size a
And the ratio of the longest particle size b to the recrystallized grains having a value of less than 2 is 50% by volume or more of all recrystallized grains, and the average of the recrystallized grains constituting the recrystallized grain texture An R-Fe-Co-B-based anisotropic magnet, which is a hot pressed compact having a recrystallized grain size of 0.05 to 20 µm. 2. An R-form containing R, Fe, Co and B as main components.
This is an Fe—Co—B based anisotropic magnet, wherein the anisotropic magnet is: R: 10 to 20%, Co: 0.1 to 50%, B: 3 to 20%, Ti, Total of one or more of V and Ta: 0.
001-5.0%, the balance being Fe and inevitable impurities, and R ₂ (F) having a tetragonal structure obtained by HDDR treatment.
e, Co) _14B type intermetallic compound phase as the main phase, and a recrystallized grain texture in which the recrystallized grains are aggregated adjacent to each other. Shortest particle size a
And the ratio of the longest particle size b to the recrystallized grains having a value of less than 2 is 50% by volume or more of all recrystallized grains, and the average of the recrystallized grains constituting the recrystallized grain texture An R-Fe-Co-B anisotropic magnet, which is a hot isostatic press formed body having a recrystallized particle size of 0.05 to 20 µm. 3. The average recrystallized particle size is 0.05 to 3 μm.
m, wherein R is
Fe-Co-B based anisotropic magnet.