JPH11121215A - Manufacture of rare-earth magnetic powder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the magnetic characteristics by suppressing the formation of the magnetic-characteristic obstructing phase such as α Fe in mother alloy provided for nitriding, enhancing the content rate of the minute grain diameter in R3 (Fe, M, and B)29 Ny phase or R3 (Pe and M)29 Ny phase, and sharpening the distribution of particle diameter of the mother alloy provided for nitriding. SOLUTION: Alloy melted liquid, the composition components of which is RαFe100-(α+β+γ)MβBγ(R is one kind or two or more kinds of any of rare- earth elements including Y, M is one kind or two or more kinds of any of Al, Ti, V, Cr, Mn, Cu, Ga, Zr, Nb, Mo, Hf, Ta and W, 5<=α<=18, 1<=β<=50 and 0.1<=γ<=5) is cast into a cast body having the plate thickness in the range of 0.03-10 nm by a strip cast method. Then, the body is crushed after the body has been made to be the powder body, and nitriding is performed. The isotropic magnetic material powder, wherein R3 (Fe, M and B)29 Ny is included as the main phase, and the composition of the components is RαFe100-(α+β+γ+$δ) MβBγNδ (5<=α<=18, 1<=β<=50, 0.1<=γ<=5 and 4<=δ<=30), can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an R-Fe-MN system using a strip casting method, and an R-Fe-MBN.
The present invention relates to a method for producing a system magnet powder.

[0002]

2. Description of the Related Art Conventionally, ultra-quenched Nd-Fe-B-based magnetic powder has been frequently used as magnetic powder for isotropic rare earth bonded magnets, but its Curie temperature is as low as about 300 ° C. ), The use at high temperatures has been limited. Recently, Sm ₂ Fe ₁₇
Together they show a Curie temperature of 160 ° C. is high 470 ° C. than Nd ₂ Fe ₁₄ B compound by a compound to absorb nitrogen, the anisotropic magnetic field (75kOe) of the anisotropic magnetic field also Nd ₂ Fe ₁₄ B compound It is reported to be 260 kOe, which is much higher, and industrialization as a magnetic powder for bonded magnets is being studied. Although nitride Sm ₂ Fe ₁₇ N _x of Sm ₂ Fe ₁₇ is produced by a gas nitriding method or the like, Sm ₂ Fe ₁₇ N _x magnetic powder number and particle size μm
Otherwise, a high iHc of 5 kOe or more cannot be obtained, and magnetic particles of this particle size are easily oxidized, deteriorating the magnet characteristics, and are accompanied by the danger of ignition. When the Sm ₂ Fe ₁₇ N _x magnetic powder of several μm is formed into a bonded magnet, the density of the formed body cannot be increased and a rare-earth bonded magnet having a high energy product cannot be obtained.
There is a problem that the moldability is very poor and the working efficiency is significantly reduced. Although it has been reported that high iHc can be obtained by a special manufacturing method such as a mechanical alloying method, this method is suitable for small-scale production on a laboratory scale, but its cost performance is inferior and has not led to mass production. Further, besides Sm ₂ Fe ₁₇ N _x nitride, TbCu
Japanese Patent Application Laid-Open No. 8-31 discloses a method of producing an SmFe ₇ alloy having a _7- type crystal structure by a super-quenching method and then nitriding to produce an isotropic ultra-quenched magnet powder of Sm ₂ Fe ₇ N _x.
Although disclosed in No. 6018, since this alloy is a metastable phase that does not exist in an equilibrium state, it requires high-precision quenching rate control technology, and has a problem in production.

The recently reported R ₃ (Fe, M) ₂₉ alloy is also promising as a permanent magnet material because its nitride R ₃ (Fe, M) ₂₉ N _y exhibits uniaxial magnetic anisotropy. Have been. Bo-Ping Hu et al. Found that the coercive force can be increased by finely pulverizing this alloy-based Sm ₃ (Fe, Ti) _{29 Ny} alloy with a ball mill to an average particle size of 15 μm.
(J. Phys .: Condens. Matter 6 (1994) L197-L200). However, this also has an average particle size of 15 μm.
It is difficult to put it into practical use as a magnetic powder for bonded magnets because of the small molded body density and poor moldability due to the small m.

In Japanese Patent Application Laid-Open No. Hei 8-111305, this R ₃
(Fe, M) high coercivity in powder 10~200μm by introducing N or C with a ₂₉ alloy is disclosed to be obtained, ammonia after producing the R ₃ (Fe, M) ₂₉ master alloy Although nitriding is performed using gas or methane gas, the mother alloy to be subjected to nitriding is manufactured using the conventional casting method (high-frequency melting method), and then 1150 ° C.
It is proposed below to perform a homogenization process. But,
According to the study of the present inventors, precipitation of a soft magnetic phase such as αFe is remarkably observed in a conventional casting of the above alloy, and αFe is added to a nitride magnet powder particle finally obtained by using this.
It has been found that these properties remain and lower the magnetic properties. Further, when the above-mentioned homogenization treatment at 1150 ° C. or less is performed to re-dissolve αFe precipitated in the conventional casting into the mother alloy, the crystal grain size of the R ₃ (Fe, M) ₂₉ phase of the mother alloy becomes large. R ₃ (Fe, M) obtained by nitriding this
There is a problem that the magnetic characteristics of the _{29 Ny} phase are deteriorated.

[0005]

SUMMARY OF THE INVENTION In view of the above-mentioned conventional problems, an object of the present invention is to form a magnetic property-inhibiting phase such as αFe which cannot form a magnet main phase by a nitriding treatment in a mother alloy to be subjected to nitriding. And R ₃ (Fe, M,
B) R ₃ (F) having a fine grain size by suppressing coarsening of the grain size of the ₂₉ phase or the R ₃ (Fe, M) ₂₉ phase
e, M, B) _{29 Ny} phase or R ₃ (Fe, M) _{29 Ny} phase is increased, and the particle size distribution of the master alloy powder to be subjected to nitriding is sharpened to be substantially uniform in each powder particle. It is an object of the present invention to provide a method for producing a rare earth magnet powder in which an excellent nitride is formed so that good magnetic properties can be obtained.

[0006]

That is, according to the present invention, there is provided a composition comprising RαFe100- (α + β + γ) MβBγ (where R is one or more of rare earth elements including Y,
M is Al, Ti, V, Cr, Mn, Cu, Ga, Zr,
Any one or more of Nb, Mo, Hf, Ta, and W, α, β, and γ are in the following ranges in atomic percentage. )
0.03 to 10 of the molten alloy by strip casting
After casting the castings of mm, by nitriding after without a powder by crushing, wherein _{R 3 (Fe, M, B} ) the ₂₉ N _y as a main phase, component composition is RαFe100- (α + β + γ + δ) MβBγN
A method for producing a rare earth magnet powder, characterized by obtaining an isotropic magnet material powder having δ (α, β, γ, and δ are in the following range in atomic percentage). 5 ≦ α ≦ 18 1 ≦ β ≦ 50 0.1 ≦ γ ≦ 54 4 ≦ δ ≦ 30 According to the present invention, a soft magnetic phase such as αFe in the cast of the R-Fe-MBN-based alloy obtained according to the present invention. Precipitation is suppressed,
The particle size distribution of the mother alloy powder to be subjected to nitriding can be sharpened.

Further, according to the present invention, the component composition is RαFe100-
(α + β) Mβ (R is any one of the rare earth elements including Y
M or Al, Ti, V, Cr,
Mn, Cu, Ga, Zr, Nb, Mo, Hf, Ta, W
Α or β is in the following range in atomic percentage. ) Is cast into a casting having a thickness of 0.03 to 10 mm by strip casting, crushed into powder, and then nitrided to obtain R ₃ (Fe, M) ₂₉
Include N _y as a main phase, component composition is RαFe100- (α + β
+ Δ) MβNδ (α, β, and δ are in the following range in atomic percentages): a method for producing a rare earth magnet powder, characterized by obtaining an isotropic magnet material powder. 5 ≦ α ≦ 18 1 ≦ β ≦ 504 4 ≦ δ ≦ 30 According to the present invention, precipitation of a soft magnetic phase such as αFe can be suppressed in the obtained R-Fe-MN-based alloy casting, and nitriding can be prevented. The particle size distribution of the provided mother alloy powder can be sharpened.

In the present invention, the cast body cast by the strip cast method is subjected to a homogenization treatment in which the cast body is heated and maintained in a vacuum or an inert gas atmosphere at a temperature of 1000 to 1200 ° C. for 0.5 to 48 hours, and then subjected to hydrogen treatment. R ₃ (Fe, M,
B) It is preferable to make the ₂₉ phase or the R ₃ (Fe, M) ₂₉ phase finer and nitride it. By processing in this way,
It suppresses the formation of αFe and the like, forms a uniform nitride that effectively contributes to the magnet properties, and has a fine crystal R ₃ (F
(e, M, B) _{29 Ny} phase or R ₃ (Fe, M) _{29 Ny} phase can be obtained as a rare earth magnet powder.

The rare earth element R may be Y, La, C
e, Pr, Nd, Sm, Eu, Gd, Tb, Dy, H
At least one of o, Er, Tm, Yb, and Lu may be included, and a mixture of two or more rare earth elements such as misch metal and dymium may be used. Preferred rare earth elements R include Y, Ce, Pr, Nd, Sm, Gd,
Any one or more of Dy and Er, and more preferably any one of Y, Ce, Pr, Nd and Sm
Species or a combination of two or more, and particularly preferred is Sm. Furthermore, 50 atomic% or more, preferably 70% of the R component
By setting the above to Sm, a remarkably high iHc can be obtained. Here, the rare-earth element R may have a purity that can be obtained by industrial production, and O, H,
Impurity elements such as C, Al, Si, Na, Mg, and Ca may be contained. The rare earth magnet material according to the present invention has R
Contains 5 to 18 atomic% of a component. When the R component is less than 5 atomic%, the precipitation of a soft magnetic phase containing a large amount of iron component is promoted and i
When Hc decreases and exceeds 18 atomic%, a nonmagnetic R-rich compound precipitates and lowers the saturation magnetic flux density. A more preferable range of the R component is 6 to 12 atomic%.

The rare earth magnet material according to the present invention contains 50 Fe.
It is preferable to contain at least atomic%. If Fe is less than 50%, the magnetization becomes small, which is not preferable.

The element M has the effect of stabilizing the R ₃ (Fe, M, B) ₂₉ phase or the R ₃ (Fe, M) ₂₉ phase and increasing the content of the magnet main phase after nitriding. . The addition amount of the M element varies depending on the type of the M element. However, if the addition of any of the M elements exceeds 50 atomic%, the crystal structure changes to a ThMn ₁₂ type, iHc becomes very small, and if less than 1 atomic%, the Th becomes less. The abundance ratio of the soft magnetic phase having the ₂ Zn ₁₇ type increases, and the relative proportion of the R ₃ (Fe, M, B) _{29 Ny} phase or R ₃ (Fe,
M) The content of the _{29 Ny} phase decreases. Therefore, the preferable addition amount of the element M is 1 to 50 atomic%. Preferred M elements are any one or more of Ti, Mn, Cr, Zr and V.

R ₃ (Fe, M, B) ₂₉ phase or R ₃ (F
e, M) The nitrogen N introduced into the ₂₉ phase is preferably 4 to 30 atomic%. If the nitrogen N is less than 4 at%, the magnetization is low, and if it exceeds 30 at%, it is difficult to improve the coercive force. More preferably, the content of nitrogen N is 10 to 20 atomic%.

In the rare earth magnet material according to the present invention, B is set to 0.1.
It is preferable to contain 1 to 5 atomic%. If B is less than 0.1 at.% Or more than 5 at.
₃ (Fe, M, B) ₂₉ N _y phase generation becomes unstable.

In the rare earth magnet material according to the present invention, F
It is preferable to replace 0.01 to 30 atomic% of e with Co and / or Ni. The Curie temperature rises by introducing Co and / or Ni, and the temperature coefficient (η) of iHc improves. Fe by Co and / or Ni
A more preferable range of the substitution amount is 1 to 20 atomic%. If the substitution amount exceeds 30 atomic%, the saturation magnetic flux density and iHc
When the content is less than 1 atomic%, the effect of adding Co and / or Ni is not recognized.

The average particle size of the rare earth magnet material powder according to the present invention is preferably 20 to 500 μm. 20 μm
If it is less than 500 μm, quality deterioration due to oxidation becomes remarkable.
Is exceeded, the R-Fe-MBN-based nitride, R-
This causes a problem that the Fe-M-N-based nitride is not formed. The more preferable average particle diameter of the powder is 30 to 400 μm. In the present invention, it is preferable that the crystal grain size range of the nitride magnet main phase is 0.05 to 1.0 μm. 0.0
Industrialization of materials having a size of less than 5 μm is substantially difficult.
If it exceeds 0 μm, iHc is significantly reduced. A preferred range of the crystal grain size is 0.1 to 0.5 μm.

According to the present invention, the content of the R ₃ (Fe, M, B) _{29 Ny} phase in the rare earth magnet material is set to 60% in area ratio.
It is preferably at least 75%. Also,
According to the present invention, R ₃ (Fe,
M) The content of the _{29 Ny} phase can be 50% or more, preferably 60% or more in terms of area ratio. The above area ratio improvement is iH
It is closely related to the improvement of c.

In the present invention, it is preferable to appropriately adjust the particle size distribution of the mother alloy powder by pulverizing and classifying the powder as necessary before performing the nitriding treatment in order to perform a uniform nitriding treatment. In the present invention, known nitriding means (for example, gas nitriding, plasma nitriding, ion nitriding, salt bath nitriding, etc.) can be adopted. To explain an application example of a practical gas nitriding method, _{2 to} 10 atm of N ₂ gas or H ₂ gas is 1 to 95 atm.
The mass or powder of the master alloy according to the present invention is placed in a mixed gas consisting of 1 mol% and the balance consisting of N ₂ gas or a mixture gas consisting of 1 to 50 mol% of NH ₃ gas and the balance consisting of H ₂ gas. ×
By holding for 0.1 to 30 hours, the rare earth magnet powder according to the present invention is obtained.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the present invention, αF is obtained by a strip cast method such as a single roll or twin roll system.
A cast body in which precipitation of e is suppressed is obtained, and by using this cast body, the particle size distribution of the mother alloy powder is sharp when the pulverization is performed through homogenization treatment and hydrogen treatment in a later step, and The mother alloy crystal can be made finer, and a nitride main phase exhibiting magnetic properties can be formed with a very high content in the powder particles substantially uniformly by a subsequent nitriding treatment. Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these examples.

(Examples 1 to 7) Sm having a purity of 99.9%,
After mixing Fe, Ti, and B into a mother alloy composition corresponding to the nitride magnet powder shown in Table 1, the molten alloy melted in a high-frequency melting furnace under an argon gas atmosphere was installed on two copper rolls having a diameter of 300 mm. A flaky cast piece having a plate thickness of 2 mm was obtained using a roll-type strip caster. When X-ray diffraction of this cast piece was performed using Cu-Kα ray, the diffraction peak could be indexed as R ₃ (Fe, M, B) ₂₉ phase, that is, the diffraction peak of soft magnetic phase such as αFe was recognized. I couldn't. This Sm-Fe-Ti-B based magnetic powder is 1a
It was heated and maintained at 800 ° C. for 1 hour in a hydrogen gas of tm, and further maintained at 800 ° C. for 1 hour at a hydrogen partial pressure of 5 × 10 ⁻² Torr to perform dehydrogenation treatment to obtain a powder. Next, add the powder
The sample was kept in a nitrogen gas of atm at 450 ° C. × 5 hours and then cooled. Subsequently, annealing was performed at 400 ° C. for 0.5 hour in an Ar gas stream. S of Examples 1 to 7 thus obtained
About m-Fe-Ti-BN nitride magnet powder, composition, average particle size (dp) of powder, average crystal grain size (dc) and area ratio of magnet main phase, intensity of saturation magnetization at 25 ° C Table 1 shows the results of measuring (σ) and iHc and the temperature coefficient (η) of iHc at 25 to 100 ° C. dp was measured with a particle size distribution analyzer (Heros Rhodes) manufactured by JEOL Ltd. The area ratio was determined by preparing samples for optical microscope observation using the powders of the respective examples, and applying a magnification of 1 to each sample.
Photograph the optical microscope at a magnification of 000x and use NIRE
It is obtained by reading and image processing with a scanner provided in an image processing apparatus (trade name LUZEX2) manufactured by CO Company, and shows the area ratio of the main phase of the magnet in the observed tissues in all fields of view. dc is a value obtained by observing an arbitrary cross section of the above observation sample with a microscope, measuring the maximum particle size of each of 40 crystal grains arbitrarily selected in the R ₃ (Fe, M, B) ₂₉ phase, and averaging. is there.

(Comparative Examples 1 to 7) Sm having a purity of 99.9%,
After mixing Fe, Ti, and B into a mother alloy composition corresponding to the nitride magnet powder in Table 1, the alloy melt melted in a high-frequency melting furnace under an argon gas atmosphere was subjected to 50 mm × 100 mm ×
Casting mass produced by casting into a 150 mm mold is about 30 m
The film was broken to an m-square or less and subjected to a homogenization treatment at 1150 ° C. × 50 hours. Next, after performing heating and dehydrogenation treatment in hydrogen under the same conditions as in Example 1, nitriding treatment was performed to obtain nitride magnet powders of Comparative Examples 1 to 7. Thereafter, in the same manner as in Examples 1 to 7, the composition, the average particle diameter (dp) of the powder, the average crystal particle diameter (dc) and the area ratio of the magnet main phase, the intensity (σ) of the saturation magnetization at 25 ° C., and iHc IHc at 25-100 ° C
Table 1 shows the results of measuring the temperature coefficient (η) of

[0021]

[Table 1]

(Examples 8 to 11) The same procedure as in Example 1 was carried out except that a mother alloy composition corresponding to the nitride magnet powder shown in Table 2 was used, and a flaky cast piece having a thickness of 9 mm was obtained using a twin-roll strip caster. Similarly, nitride magnet powders of Examples 8 to 11 shown in Table 2 were obtained. X-ray diffraction of this cast piece was determined by Cu-Kα
The diffraction peak was R ₃ (Fe, M).
Indexing was possible as ₂₉ phases, that is, no diffraction peak of a soft magnetic phase such as αFe was observed. The Sm-Fe-Ti-N-based nitride magnet powders of Examples 8 to 11 thus obtained each had dc = 0.6 µm, the area ratio of the magnet main phase was 60% or more, and the composition and powder particle size distribution. And dp, 25
Squareness ratio (Hk / iHc) at ℃ and saturation magnetization intensity (σ), i
Table 2 shows the results of measuring Hc. Here, Hk is such that the magnetization is the remanent magnetization (applied external magnetic field = 0) in the second quadrant of the magnetization curve.
The value of the magnetic field is 90% of the value of the magnetization at the time of (1).

(Comparative Examples 8 to 11) S having a purity of 99.9%
m, Fe, Ti, and B were blended into a mother alloy composition corresponding to the nitride magnet powder in Table 2 and then melted in a high-frequency melting furnace under an argon gas atmosphere to obtain a 50 mm × 100 m
Approximately 3 ingots cast by casting into a mx150mm mold
It was fractured to 0 mm square or less, and a homogenization treatment at 1150 ° C. × 50 hours was performed. Next, after performing heating and dehydrogenation treatment in hydrogen under the same conditions as in Example 1, nitriding treatment was performed.
As a result, 11 nitride magnet powders (each having a dc exceeding 1 μm and an area ratio of the magnet main phase being 49%) were obtained. Thereafter, the results of evaluation in the same manner as in Examples 8 to 11 are shown in Table 2.

[0024]

[Table 2]

From the results shown in Tables 1 and 2, it is possible to obtain a nitride magnet powder having a high area ratio of the magnet main phase, fine crystal grains and a narrow particle size distribution by using the strip cast material. It can be seen that the powder has high magnetic properties that can be practically used as a powder for bond-magnet.

According to the present invention, the present invention is not limited to the above-described embodiment, and the thickness of the cast obtained by the strip casting method is in the range of 0.03 to 10 mm.
It is possible to obtain a rare earth nitride magnet powder having much better magnetic properties than the comparative example.

[0027]

According to the present invention, R ₃ (Fe, M, B)
A rare earth magnet powder having a high content of ₂₉ N _y phase or R ₃ (Fe, M) ₂₉ N _y phase and having fine crystal grains and a sharp particle size distribution can be provided.

Claims (3)

[Claims] (1) a composition of RαFe100- (α + β + γ) Mβ;
Bγ (R is any one or more of rare earth elements including Y, M is Al, Ti, V, Cr, Mn, C
Any one or more of u, Ga, Zr, Nb, Mo, Hf, Ta, and W, α, β, and γ are in the following ranges in atomic percentages. ) Is cast into a casting having a thickness of 0.03 to 10 mm by a strip casting method, crushed into powder, and then nitrided to obtain R ₃ (Fe, M, B) _29.
Include N _y as a main phase, component composition is RαFe100- (α + β +
γ + δ) MβBγNδ (α, β, γ, and δ are in the following range in atomic percentage): A method for producing a rare earth magnet powder, characterized by obtaining an isotropic magnet material powder. 5 ≦ α ≦ 18 1 ≦ β ≦ 50 0.1 ≦ γ ≦ 5 4 ≦ δ ≦ 30 2. A composition comprising RαFe100- (α + β) Mβ
(R is one or more of rare earth elements including Y, and M is Al, Ti, V, Cr, Mn, Cu,
Any one of Ga, Zr, Nb, Mo, Hf, Ta, and W
The kind or two or more kinds, α and β are in the following ranges in atomic percentage. ) Thickness of molten alloy by strip casting method
After casting the castings of 0.03～10Mm, by nitriding after without a powder by crushing, wherein R ₃ (Fe, M) and ₂₉ N _y as a main phase, component composition is RαFe100- (α + β + δ) MβNδ
(Where α, β, and δ are in atomic percentage in the following range): A method for producing a rare earth magnet powder, characterized by obtaining an isotropic magnet material powder. 5 ≦ α ≦ 18 1 ≦ β ≦ 50 4 ≦ δ ≦ 30 3. A composition comprising RαFe100- (α + β + γ) Mβ
Bγ (R is any one or more of rare earth elements including Y, M is Al, Ti, V, Cr, Mn, C
Any one or more of u, Ga, Zr, Nb, Mo, Hf, Ta, and W, and α, β, and γ are in the following ranges in atomic percentage. ) Is cast into a casting having a thickness of 0.03 to 10 mm by the strip casting method, and then the casting is placed in a vacuum or in an inert gas atmosphere at 1000 to 1200 ° C x 0.5.
A homogenization treatment of heating and holding for ~ 48 hours is performed, followed by hydrogen treatment of the R ₃ (Fe, M, B) ₂₉ phase or R
_{The 3} (Fe, M) ₂₉ phase is refined, pulverized to a powder, and then nitrided to obtain R ₃ (Fe, M, B) _{29 Ny} or R ₃ (Fe, M) _{29 Ny} . Included as the main phase, and the component composition was RαFe100- (α + β + γ + δ) MβBγNδ (α, β,
γ and δ are in the following range in atomic percentage. A method for producing rare earth magnet powder, characterized in that isotropic magnet material powder is obtained. 5 ≦ α ≦ 18 1 ≦ β ≦ 500 0 ≦ γ ≦ 5 4 ≦ δ ≦ 30