JP2898463B2 - Method for producing raw material powder for R-Fe-B-based permanent magnet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a raw material powder used for producing an R--Fe--B permanent magnet containing R (at least one of rare earth elements including Y), Fe and B as main components. According to the production method, a B-rich phase or an Nd-rich phase, which deteriorates magnet properties, is obtained by adding and blending an adjustment alloy powder containing an R ₂ Fe ₁₇ phase to a main phase alloy powder having an R ₂ Fe ₁₄ B phase as a main phase. relates to the production how raw material powder for R-Fe-B permanent magnet having a reduced amount of phase.

[0002]

2. Description of the Related Art Today, a typical high performance permanent magnet R
-Fe-B based permanent magnet (JP-A-59-46008)
Exhibits high magnet properties in a structure having a main phase of a ternary tetragonal compound and an R-rich phase, iHc of 25 kOe or more,
(BH) max is 45 MGOe or more, which shows remarkably high performance even when compared with conventional high performance rare earth cobalt magnets. Further, R-Fe-B permanent magnets having various compositions have been proposed so as to exhibit various magnet properties selected according to the application.

[0003] In order to produce R-Fe-B sintered permanent magnets having the above-mentioned various compositions, it is necessary to produce alloy powders for magnets having a required composition, using a rare earth raw material reduced by electrolysis. It is melted and cast into a mold to form an alloy lump having a required magnet composition, and then pulverized to obtain an alloy powder having a required particle size (Japanese Patent Application Laid-Open Nos. 60-63304 and 60-1).
No. 19701) and a direct reduction-diffusion method for preparing a magnet composition alloy powder directly using a rare earth oxide, Fe powder, etc.
-219404 and JP-A-60-77943.

In the melting and pulverizing method, an Fe primary crystal is liable to be generated during casting, and the R-rich phase is largely segregated.
An alloy powder having a relatively low oxygen content is obtained.

[0005] The direct reduction diffusion method has the advantage that the steps of melting and coarse grinding can be omitted when preparing the raw material powder for the magnet as compared with the above melting and grinding method.
_{Since the} R-rich phase is formed around the ₂ Fe ₁₄ B main phase, and the size of the R-rich phase is small and well dispersed as compared with the former, it is easily oxidized at the time of production and the oxygen content is high. However, depending on the magnet composition, there is a problem that the rare earth element is consumed and causes a variation in magnet characteristics.

[0006]

SUMMARY OF THE INVENTION The inventor has previously proposed RF
In order to reduce the oxygen content in the alloy powder that degrades the magnetic properties of the e-B permanent magnet, an alloy powder with a composition close to the R ₂ Fe ₁₄ B phase with a small R-rich phase is produced by the direct reduction diffusion method. In addition, the R-rich alloy powder is converted into an R ₃ Co phase (a part or most of Co is Fe) by adding a Co element.
To prepare an intermetallic compound powder comprising an R ₂ (Fe, Co) ₁₇ phase or the like containing
Proposal of raw material powder for eB-based permanent magnet (Japanese Patent Application No. 2-229)
No. 685).

[0007] The raw material powder for R-Fe-B permanent magnet proposed above is extremely effective in reducing the oxygen content in the alloy powder and the obtained magnet, but the main phase R ₂ F
In addition to the e ₁₄ B phase, there are a B-rich phase and an R-rich phase as a grain boundary phase, and it is extremely difficult to precisely control the abundance of each of these phases, causing a variation in magnet properties.

According to the present invention, the B-rich phase and the R-rich phase of the magnet constituting phase, which hinder the improvement of the performance of the R-Fe-B-based permanent magnet, can be reduced as much as possible, and the main phase of R ₂ Fe ₁₄ B
A method for producing a raw material powder for an R-Fe-B-based permanent magnet, which can increase the phase, further reduce the oxygen content in the alloy powder, and can easily provide an alloy powder having a composition corresponding to various magnet properties. The purpose is.

[0009]

In general, an R-Fe alloy,
For example, in an Nd—Fe alloy, the Nd ₂ Fe ₁₇ phase is an intermetallic compound having a Curie point near room temperature and having an easy magnetization direction in the C plane. If the amount is less than 6 atomic%, it has been reported that, for example, an Nd ₂ Fe ₁₇ phase is formed in the magnet and the coercive force is reduced. However, as a result of various studies, the inventor found that an R ₂ Fe ₁₇ phase was added to an R—Fe—B-based alloy powder having an R ₂ Fe ₁₄ B phase as a main phase.
For example, a raw material powder in which a specific amount of an R-Fe alloy powder containing a Nd ₂ Fe ₁₇ phase is added and blended is a mixture of Nd in the Nd-rich phase of the grain boundary phase and Nd ₂ Fe ₁₇ in the R-Fe alloy powder. When the crystallization temperature is around 690 ° C., for example, Nd + Nd ₂ Fe ₁₇
It has been found that the low-melting liquid phase promotes the sintering of the R-Fe-B-based alloy powder due to the reaction of the phase ← → liquid phase.

An adjusting alloy powder containing a Nd ₂ Fe ₁₇ phase and R ₂
The R-Fe-B-based alloy powder having the Fe ₁₄ B phase as a main phase has the following reaction during sintering, and has an effect of increasing the R ₂ Fe ₁₄ B phase as a main phase. 13 / 17Nd ₂ Fe ₁₇ + ／ Nd _1.1 Fe ₄ B ₄ +13
3/6800 Nd → Nd ₂ Fe ₁₄ B In other words, in the above reaction formula, the present inventors have found that the Nd ₂ Fe ₁₇ phase in the alloy powder for adjustment and the B-rich phase and Nd in the main phase R—Fe—B alloy powder Since the Nd ₂ Fe ₁₄ B phase is newly generated by the reaction with the rich phase, the permanent magnet obtained only with the alloy powder having the main phase of the R ₂ Fe ₁₄ B phase according to the conventional method has magnet properties. The present inventors have found that the amounts of the B-rich phase and the Nd-rich phase, which are one of the factors that cause the deterioration of, can be reduced, and completed the present invention.

That is, the present invention relates to a method for preparing an R (where R is at least one of rare earth elements including Y) from 10 atomic% to 3 atomic%.
0 atomic%, B4 atomic% to 40 atomic%, balance Fe (however, F
A portion of e consists hands substitutions can) and unavoidable impurities Co, the R ₂ Fe ₁₄ B phase alloy powder with the main phase, R
(Where R is at least one of rare earth elements including Y)
50 atom% or less, the balance Fe (however, one part of Fe is Co, N
i) which can be replaced by one or two of i) and unavoidable impurities, mixed with an adjustment alloy powder containing an R ₂ Fe ₁₇ phase
R characterized by being added and blended in an amount of not more than 60 wt % of the powder.
This is a method for producing a raw material powder for an Fe-B-based permanent magnet.

In the present invention, a specific amount of R, Fe, B
R-F containing R ₂ Fe ₁₇ phase of 50 atomic% or less added and blended into an alloy powder having an R ₂ Fe ₁₄ B phase as a main phase having
The reason why the addition amount of the alloy powder for adjusting the e-system is set to 60 wt % or less of the mixed powder is that if it exceeds 60 wt %, it is uniaxially anisotropic when molded in a magnetic field to produce an anisotropic magnet. Some R
_This is because the amount of the ₂ Fe ₁₄ B phase is reduced and the degree of orientation is lowered, which is not preferable, and causes a reduction in Br. More preferable addition amount is 0.1 to 40 wt%.

The rare earth element R used in the present invention is a rare earth element containing Y and including light rare earths and heavy rare earths, and at least one of them, preferably Nd, P
A light rare earth element such as r is mainly used, or a mixture with Nd, Pr or the like is used. That is, as R, Nd, P
r, La, Ce, Tb, Dy, Ho, Er, Eu, S
m, Gd, Pm, Tm, Yb, Lu, and Y can be used. This R may not be a pure rare earth element, and may contain impurities that are unavoidable in production within the industrially available range.

In order to obtain an alloy powder composed of the main phase of R ₂ Fe ₁₄ B, when R is less than 10 atomic%, the residual iron portion where R and B do not diffuse increases, and when R exceeds 30 atomic%, the R-rich phase is increased. Is increased to increase the oxygen content, so that R is set to 10 at% to 30 at%. A more preferred R content is 12 atomic%.
２０20 at%.

If B is less than 4 at%, a high coercive force (iHc) cannot be obtained, and if it exceeds 40 at%, the residual magnetic flux density (Br) decreases, so that an excellent permanent magnet cannot be obtained. , B is 4 to 40 atomic%. A more preferable B amount is from 6 at% to 20 at%.

Further, the balance consists of Fe and unavoidable impurities, and the content of Fe is preferably in the range of 30 at% to 86 at%. If Fe is less than 30 atomic%, the rare earth element and B become relatively rich, and the R-rich phase and the B-rich phase increase, and
If the content exceeds 6 atomic%, the rare earth elements and B become relatively small, and the residual Fe portion increases, resulting in non-uniform alloy powder. More preferably, the Fe content is 60 atomic% to 82 atomic%.
Atomic%. One or two types of Co and Ni in the main phase alloy powder are replaced by Fe in the R ₂ Fe ₁₄ B main phase to lower the coercive force, so that Co is 10 atomic% or less and Ni is 3 atomic%. % Or less. However, when a part of Fe is substituted with Co or Ni described above, the content of Fe is in the range of 17 atomic% to 84 atomic%.

In order to obtain an adjusting alloy powder containing the R ₂ Fe ₁₇ phase, if R exceeds 50 atomic%, there is a problem such as oxidation at the time of preparing the alloy powder, which is not preferable.
35 atomic%. Further, the balance consists of Fe and inevitable impurities, and the content of Fe is preferably in the range of 65 to 95 atomic%.

In the present invention, the alloy powder containing the R ₂ Fe ₁₄ B phase as the main phase and the adjusting alloy powder containing the R ₂ Fe ₁₇ phase are each a known alloy such as a direct reduction diffusion method or a melting / pulverizing method. It can be manufactured by a powder manufacturing method.

When the obtained powder is used as it is, if the particle size of the alloy powder is too large, the magnetic properties of the permanent magnet, especially a high coercive force, cannot be obtained. That is, press molding, sintering, oxidation in the aging process is remarkable, excellent magnetic properties cannot be obtained, and if it exceeds 80 μm, it causes a decrease in coercive force, so that an average particle size of 1 to 80 μm is preferable. In order to obtain excellent magnetic properties, an average particle size of 2
An alloy powder of 10 to 10 μm is desirable. Further, in order to obtain an excellent R-Fe-B-based permanent magnet having both a high residual magnetic flux density and a high coercive force using the obtained alloy powder,
The blended raw material powders were R12 atomic% to 25 atomic%, B4
Atomic% to 10 atomic%, Co 0.1 atomic% to 10 atomic%,
A composition of 55 atomic% to 83.9 atomic% of Fe is preferable.

Further, the compounded alloy powder containing the R ₂ Fe ₁₄ B phase as a main phase and / or the adjusting alloy powder containing the R ₂ Fe ₁₇ phase are added with Cu 3.5 atomic% or less, S 2.5 atomic% or less, Ti 4.5 atomic% or less, Si 15 atomic% or less, V9.5 atomic% or less, Nb 12.5 atomic% or less, Ta 10.5 atomic% or less, Cr 8.5 atomic% or less, Mo 9.5 atomic% or less, W9.5 Atomic% or less, Mn 3.5 at% or less, Al 9.5 at% or less, Sb 2.5 at% or less, Ge 7 at% or less, Sn 3.5 at% or less, Zr 5.5 at% or less, Hf 5.5 at% or less. , 8.5 atomic% or less of Ca, 8.5 atomic% or less of Mg, 7.0 atomic% or less of Sr, 7.0 atomic% or less of Ba, and 7.0 atomic% or less of Be. High permanent magnet It becomes possible to increase magnetic force, increase corrosion resistance, and improve temperature characteristics.

When the composition of the permanent magnet manufactured by using the alloy powder according to the present invention is R12 atomic% to 25 atomic%, B4 atomic% to 10 atomic%, Co 30 atomic% or less, and Fe 35 atomic% to 84 atomic%, The resulting magnetic anisotropic permanent magnet has a coercive force _i H _C ≧ 5 kOe, (BH) max ≧ 20 MG
It shows the magnetic properties of Oe, and the temperature coefficient of the residual magnetic flux density is 0.1% / ° C. or less, and excellent properties are obtained. Further, in the case where the main component of R in the permanent magnet composition occupies 50% or more of the light rare earth metal, R12 atom% to 20 atom%, B4 atom% to 10 atom%, Fe50 atom% to 84 atom%.
When the alloy contains less than 20 atomic% of Co and less than 20 atomic% of Co, it shows the best magnetic properties. In particular, rare earth metals are Nd, Pr, Dy.
In the case of (BH) max, the maximum value is 40 MGO
e or more.

[0022]

[Action] This invention is directed to main phase R ₂ Fe ₁₄ B phase R-
60% or less of the total amount of Nd ₂ Fe _{17 in the} Fe-B-based alloy powder
By adding and blending the adjustment alloy powder containing the phase, the Nd ₂ Fe ₁₇ phase in the adjustment alloy powder and the main phase system R—Fe—B
A new Nd ₂ Fe ₁₄ B phase is generated by the reaction with the B-rich phase and the Nd-rich phase in the base alloy powder, so that the amounts of the B-rich phase and the Nd-rich phase that degrade the magnet properties of the permanent magnet are adjusted. The magnet powder can be reduced, the resulting magnet can be improved in performance, the oxygen content in the alloy powder can be reduced, and an alloy powder having a composition corresponding to various magnet properties can be easily provided.

[0023]

【Example】

Example 1 Raw materials in the direct reduction diffusion method of the main phase were 407 g of Nd ₂ O ₃ (purity 98%), 15 g of Dy ₂ O ₃ (purity 99%), and Fe-containing 19.1% B content. Using 62 g of B powder and 604 g of 99% pure Fe-B powder, 264 g of 99% pure metal Ca and 49.3 g of anhydrous CaCl ₂ were mixed, and charged into a stainless steel container. And Ca reduction and diffusion were performed in an Ar gas flow at 1030 ° C. for 3 hours. After cooling, the resulting mixture was washed with water to remove unnecessary Ca. The obtained powder slurry was replaced with alcohol or the like, and then dried by heating under vacuum to obtain about 1000 g of raw material powder. The obtained powder had Nd of 14.0 atomic%, Pr of 0.8 atomic%, and Dy of 0.
5%, B7.2 atomic%, balance Fe: average particle size of about 2
The thickness was 0 μm, and the oxygen content was 2000 ppm.

The raw material of the adjusting alloy powder containing the R ₂ Fe ₁₇ phase is 124 gr of Nd metal (98% purity) and 379 gr of electrolytic iron of 99% purity. Crushed with a crusher disc mill, powder 4 of average 10 μm
50 g were obtained. The obtained powder was composed of 11 atomic% of Nd, Pr
It consisted of 0.2 atomic% and the balance of Fe, and it was confirmed by EMPA and X-ray diffraction that the Nd ₂ Fe ₁₇ phase was the majority. The oxygen content was 600 ppm.

As shown in Table 1, a predetermined amount of the alloy powder for adjustment was mixed with the main phase alloy powder by using these two raw material powders. This raw material powder is charged by a pulverizer such as a jet mill, orientated in a magnetic field of about 10 kOe, and molded at a pressure of about ² Ton / cm ^{2 in} a direction perpendicular to the magnetic field to form a 15 mm × 20
A molded body of mm × 8 mm was prepared. 107
Sintered at 0 ° C for 3 hours in Ar atmosphere, and 500 ° C for 3 hours
The aging treatment was performed for 2 hours.

Table 1 shows the relationship between the amount of the alloy powder for adjustment and the magnet properties obtained. Note that, from the magnet composition, R ₂ Fe ₁₄
When the B phase, B-rich phase, and R-rich phase (including oxides) are calculated, 88: 3: 9 in the comparative example, 91: 1.3: 7.7 in the first invention, and 93 in the second invention. : 0.1: 6.9, which indicates that the use of the alloy powder for adjustment according to the present invention can adjust the abundance of each phase constituting the magnet.

[0027]

[Table 1]

Example 2 The main phase-based raw material alloy was prepared by melting and pulverizing using 147 g of Nd metal, 23 g of Co metal, 27.5 g of Fe-B alloy, and 307 g of electrolytic iron in the same manner as the raw material powder for adjustment in Example 1. Nd 12.5 atomic%, Pr 0.2 atomic%, C
An alloy powder having a composition of o 5 at%, B 6.5 at%, and Fe 75.8 at% was obtained.

The raw material of the adjusting alloy powder containing the R ₂ Fe ₁₇ phase was obtained by direct reduction diffusion method using Nd ₂ O ₃ 260 g Dy ₂ O ₃ 80.5 g Co powder 43 g Fe powder 665 g, and Ca 190 g, Cacl _And 23 g of Nd and mixed with Nd at 10.4 at%, Pr at 0.1 atomic%, and Dy30 by the direct reduction diffusion method in the same manner as in the main phase raw material powder of Example 1.
After obtaining the adjusting alloy powder of atomic%, 5 atomic% of Co and the balance Fe, 5% of the adjusting alloy powder was mixed and mixed with 95% of the main phase alloy powder, and the sintered magnet was manufactured in the same manner as in Example 1. Produced.

The magnet composition was 12.4 atomic% b of Nd, Pr
0.2 atomic%, Dy 0.15 atomic%, Co 5 atomic%, B
6.2 atomic%, balance Fe, Br = 13.6, i
Hc = 11 kOe, (BH) max = 45.5 MGOe
The magnet characteristics were obtained. Although magnetization was attempted using only the main phase alloy powder, sintering was not possible.

Example 3 The main phase-based alloy powder prepared by the melting and pulverization method shown in Examples 1 and 2 has a composition of 18 atomic% of Nd, 0.8 atomic% of Pr, 2.0 atomic% of Dy, 2.0 atomic% of Mo2. 0 atomic%, B 10 atomic%, and the balance Fe. Similarly, an adjustment alloy powder containing the R ₂ Fe ₁₇ phase was similarly prepared by a melting and pulverizing method, and the composition was 9 at% Nd, 0.2 at% Pr, 1.0 at% Dy, and the balance Fe. .

As shown in Table 2, a predetermined amount of the adjusting alloy powder was mixed and mixed with the main phase alloy powder, and a sintered magnet was produced in the same manner as in Example 1. Table 2 shows the obtained magnet characteristics.

[0033]

[Table 2]

[0034]

Effects of the Invention The present invention, to obtain a raw material powder for R-Fe-B permanent magnets, a main phase an R ₂ Fe ₁₄ B phase R-
60% or less of the total amount of Nd ₂ Fe _{17 in the} Fe-B-based alloy powder
By adding and blending the adjustment alloy powder containing the phase, the amounts of the B-rich phase and the Nd-rich phase which degrade the magnet properties of the permanent magnet can be reduced, and as is apparent from the examples, the performance of the magnet obtained can be improved. In addition, the content of oxygen in the alloy powder can be reduced, and an alloy powder having a composition corresponding to various magnet characteristics can be easily provided.

Claims (1)

(57) [Claims] 1. R (where R is at least one of rare earth elements including Y) 10 to 30 atomic%, B 4 at%
-40 atomic%, balance Fe (however, one part of Fe is Co, Ni
It consists of one or may be replaced by two) and incidental impurities, the alloy powder with the main phase of R ₂ Fe ₁₄ B phase, R
(Where R is at least one of rare earth elements including Y)
50 atomic% or less, and the balance Fe (where a portion of Fe can be hand substituted Co) and unavoidable impurities, R ₂ Fe ₁₇
A method for producing a raw material powder for an R-Fe-B-based permanent magnet, wherein an adjustment alloy powder containing a phase is added and blended in an amount of 60 wt % or less of the mixed powder .