JP3020717B2 - 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 an R-Fe-based alloy containing R (R is at least one of rare earth elements including Y), Fe and B as main components.
It relates to a method for producing a raw material powder used in the production of B permanent magnet, almost by dissolution and powdering method according to the main phase alloy powder to main phase R ₂ Fe ₁₄ B phase, a direct reduction diffusion process R ₃ Co phase containing Co or Fe and intermetallic compound phase of R (however, part or most of Co can be replaced by Fe), partially containing R ₂ (FeCo) ₁₄ B phase, etc., and the main phase alloy powder By blending the rare earth metal-containing intermetallic compound powder in a required ratio,
The present invention relates to a method for producing a raw material powder for an R-Fe-B-based permanent magnet according to various required magnet properties.

[0002]

2. Description of the Related Art Today, a typical R-type high performance permanent magnet
Fe-B-based permanent magnet (JP-A-59-46008) exhibits high magnet properties in a structure having a main phase and an R-rich phase of a ternary tetragonal compound, iHc is 25 kOe or more, (BH) With a max of 45MGOe or more, it exhibits remarkably high performance even when compared with conventional high performance rare earth cobalt magnets. Also, R-Fe-B permanent magnets of 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 material reduced by electrolysis. It is melted and cast into a mold to create an alloy lump of the required magnet composition, which is pulverized to obtain an alloy powder of a required particle size, or the alloy lump is disintegrated by absorbing hydrogen, or powdered by spraying the molten metal. Dissolving and pulverizing method (JP-A-60-63304, JP-A-60-190701 , JP-A-60-189901), and directly produce a magnet composition alloy powder using a rare earth oxide, Fe powder, etc. There is a direct reduction diffusion method (JP-A-59-219404, JP-A-60-77943).

In the melting and pulverizing method, since the ingot can be easily crushed in the rough crushing step for preventing oxidization, an alloy powder having a relatively low oxygen content can be obtained.

[0005] direct reduction diffusion method, an advantage that it is possible to omit the step of melting and coarse grinding, etc. when creating the raw material powder for a magnet as compared with the dissolution and powdering methods described above, R ₂
The R-rich phase is created around the Fe ₁₄ B main phase, and the size of the R-rich phase is small and well dispersed compared to the former, so it is easily oxidized during production and the oxygen content is low. In many cases, depending on the magnet composition, there is a problem that the rare earth element is consumed and causes a variation in magnet characteristics.

[0006]

As described above, in the production of permanent magnets using raw material powders for R-Fe-B permanent magnets by the direct reduction diffusion method, steps such as melting and coarse grinding can be omitted, and Although the R-rich phase is small and well dispersed as a characteristic of the raw material powder, it is easily oxidized,
Compared to powdered raw materials, the oxygen content is large and slight oxidation during the magnet manufacturing process causes variations in magnet properties.

Therefore, by adding elements such as Co and Ni to make the R-rich phase an intermetallic compound that is relatively stable against oxidation, the amount of oxygen can be reduced, but these added elements are most effective. It is impossible to add and control an optimum amount to obtain a predetermined composition.

That is, in order to obtain predetermined magnet characteristics, it is necessary to change the amount of one or more rare earth elements to be added to respective required values. For example, by adding Co element, the amount of oxygen can be reduced. At this time, it is impossible to diffuse the Co element only into the R-rich phase to obtain the required phase, and the added Co element is also replaced with Fe in the main phase. In addition, elements such as Co and Ni have a problem that the coercive force of the magnet is reduced depending on the added amount, and thus the amount of oxygen cannot be easily reduced.

Conventionally, the production of raw material powders for R-Fe-B permanent magnet magnets by a dissolution / pulverization method or a direct reduction diffusion method has been carried out with a target composition corresponding to the magnet properties required at the time of melting or reduction diffusion. The composition is adjusted in advance so that

[0010] However, the metal structure of the raw material powder for the R-Fe-B permanent magnet magnet obtained by the melting / pulverization method or the direct reduction diffusion method has an R-rich phase around the main phase of the R ₂ Fe ₁₄ B phase. In addition, it is extremely difficult to adjust the proportion of each phase to a required value because it is composed of a structure in which a B-rich phase (R _{1 + ε} Fe ₁₄ B phase) exists partially. Moreover, in order to adjust to a specific composition according to the magnet properties, it is necessary to determine whether a specific element easily enters the main phase or R
It is necessary to always consider the alloy composition and the constituent elements of each phase, such as whether it is easy to enter a rich phase, and it is necessary to manufacture alloy powders aiming at a composition in a specific extremely narrow range.

The present invention has been made in view of the above situation of raw material powders used for manufacturing R-Fe-B permanent magnets, and has solved the problems in manufacturing raw material powders in the melting / pulverization method and the direct reduction diffusion method, and has been developed by the method. R-Fe-B permanent magnets, which aim to improve the quality of this permanent magnet using raw material powders and can respond to the compounding ratio of each raw material in the production of alloy powders according to various required magnet properties It aims to provide raw material powder for magnets.

[0012]

DISCLOSURE OF THE INVENTION The present invention has been studied variously for the purpose of facilitating the production of an R-Fe-B-based permanent magnet alloy powder having a composition corresponding to various required magnet properties. result, to produce alloy powders with composition close to a small R ₂ Fe ₁₄ B phase of the R-rich phase at melting and powdering method, R Te direct reduction diffusion process
Rich alloy powder can be converted to R by adding Co element and B element.
₃ Co phase (However, part or most of Co can be replaced by Fe)
By producing an intermetallic compound powder comprising R ₂ (Fe, Co) ₁₇ phase or the like containing, and mixing alloy powders by these production methods, it is possible to obtain an alloy powder having a predetermined magnet composition with a low oxygen content. . Further, in the present invention, when adding a specific element, the main phase-based alloy powder of R ₂ Fe ₁₄ B phase or R
Since any of the rich alloy powders can be selected, the effect of addition of this specific additive element can be more effectively exerted, and (BH) max is an alloy having a composition according to various magnetic properties of 20 to 45 MGOe. The inventors have found that powder can be easily provided, and have completed the present invention.

That is, the present invention relates to a method for producing R (where R is at least one of rare earth elements including Y) of 11 at% to 13 at%,
Atomic% to 12 atomic%, with the balance being Fe and unavoidable impurities,
Alternatively, a part of Fe is replaced with one or two of Co 10 atomic% or less and Ni 3 atomic% or less, and R ₂ Fe ₁₄
Alloy powder with B phase or R ₂ (FeCo) ₁₄ B phase as main phase 60wt
% To 97 wt% and R (where R is at least one of the rare earth elements including Y) 13 atomic% to 45 atomic%, B 12 atomic% or less, the balance Co (however, part or most of Co is Fe And an inevitable impurity, and an intermetallic compound phase of R or Co or Fe and R including a R ₃ Co phase by direct reduction diffusion method .
Part or most of Co can be replaced by Fe) and R ₂ (FeC
o) 40 wt% to 3 wt% of an intermetallic compound powder composed of _14B phase and the like,
A method for producing a raw material powder for an R-Fe-B-based permanent magnet, wherein the raw material powder is blended in a required composition of the R-Fe-B-based permanent magnet.

[0014]

The present invention relates to the production of R-Fe-B permanent magnets,
By creating an alloy powder with composition close to a small R ₂ Fe ₁₄ B phase of the R-rich phase at melting and powdering method, it is possible to reduce the oxygen content, also R-rich metal hand created direct reduction diffusion process By mixing the inter-compound powder, an alloy powder having a composition according to the required magnet properties can be easily and remarkably reduced in oxygen content.

Therefore, the raw material powder for an R-Fe-B permanent magnet according to the present invention can be used to a certain extent in the production of alloy powders corresponding to various required magnet properties, and can be used in a mixing ratio. In other words, by changing the type and amount of the rare earth element in accordance with various required magnet properties, when producing a raw material alloy powder for R-Fe-B-based permanent magnet having a plurality of types of compositions, (1) melting・ R (where R is at least one of rare earth elements including Y) 11 at% to 13 at%, B 4 at% to 12 by powdering method
Atomic%, balance Fe and unavoidable impurities, or furthermore, a part of Fe is replaced with 10 atomic% or less of Co, and the R-rich phase is 4% or less of R ₂ Fe ₁₄ B phase or R ₂ (FeCo). the ₁₄ B phase to produce a single type of alloy powders as a main phase, (2) more R to direct reduction diffusion process (wherein R is at least one kind of rare earth elements including Y) 13 atomic% to 45 atomic%, B12 at% or less, the balance being Co (however, part or most of Co can be replaced by Fe) and unavoidable impurities, including R ₃ Co phase or Co or Fe and R intermetallic compound phase (However, part or most of Co can be replaced with Fe) and R ₂ (FeCo) When preparing an intermetallic compound powder composed of ₁₄ B phase, etc., depending on the type and amount of the rare earth element of the target composition Producing a plurality of intermetallic compound powders in which the content ratio of the rare earth elements contained in the intermetallic compound was changed, (3) alloy powder and intermetallic compound powder comprising the required main phase 60 to 97: blended at a ratio of 40 to 3, it is possible to produce the alloy powder more compositions in accordance with the magnetic properties.

Preferred embodiments in the present invention, the mixing ratio of the intermetallic compound powder by direct reduction diffusion process and an alloy powder consisting of the required main phase by dissolution and powdering method, 60 to 97: and 40-3 When the alloy powder consisting of the required main phase is 60% or less and the intermetallic compound powder is 40% or more, it takes time to uniformly diffuse each element when manufacturing a magnet, and the amount of the intermetallic compound powder is 3% This is because the liquid phase during sintering is not sufficiently developed when the alloy powder comprising the required main phase is 97% or more.

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

Reason for limitation In order to obtain an alloy powder composed of the main phase of R ₂ Fe ₁₄ B, if R is less than 11 atomic%, the α-Fe phase crystallized during melting of the alloy increases, and
If the content exceeds atomic%, the R-rich phase increases, and it is difficult to uniformly disperse the main phase and the R-rich phase.
13 atomic%. When B is less than 4 atomic%, a high coercive force (iHc) cannot be obtained.
(Br) is reduced, so that an excellent permanent magnet cannot be obtained. Therefore, B is set to 4 atomic% to 12 atomic%. Further, the balance is composed of Fe and unavoidable impurities, Fe is preferably in the range of 75 atomic% to 85 atomic% .If Fe is less than 75 atomic%, the rare earth element becomes relatively rich, the R-rich phase increases, and 85 If it exceeds atomic%, the rare earth element becomes relatively small, the residual Fe portion increases, and a non-uniform alloy powder is obtained. Co in the main phase alloy powder is R ₂
Substituted with Fe in the Fe ₁₄ B main phase to lower the coercive force, Co is 10 atomic% or less. However, when a part of Fe is substituted by Co as described above, Fe is in the range of 62 atomic% to 85 atomic%. R ₂ Fe with less R-rich phase created by dissolution / pulverization method
It is desirable that the alloy powder composed of the _14B main phase has no R-rich phase at all from the viewpoint of the reduction of the oxygen content and the uniformity of the structure.However, if the content is 4 wt% or less, the reduction of the oxygen content is greatly increased. There is no loss.

[0019] Co or a more R ₃ Co phase in direct reduction diffusion process
An intermetallic compound powder consisting of an intermetallic compound phase of Fe and R (however, a part or most of Co can be replaced by Fe), that is, an R-rich alloy powder is an R ₃ Co phase or an R ₃ Co phase. Co
And the core part is RCo ₅ ,
_{R 2 Co 7, RCo 3,} RCo 2, R 2 Co 3, R 2 Fe 17, RFe 2, Nd 2 Co 17, N
d ₅ Co ₁₉ , Dy ₆ Fe ₂ , DyFe, etc., and the intermetallic compound phase and R ₂
It is an alloy powder composed of any one of (FeCo) ₁₄ B, R _1.11 (FeCo) ₄ B _{4 and the} like. As described above, the composition of the R-rich alloy powder changes the ratio of the rare earth element contained in the intermetallic compound according to the type and amount of the rare earth element of the target composition. However, if R is less than 13 atoms, the liquid phase during sintering is not sufficiently developed during the production of a magnet by mixing with the main phase raw material, and
If it exceeds 45 atomic%, the content of oxygen is increased, which is not preferable. Further, Co is necessary in an R-rich intermetallic compound powder in an amount of 1 atomic% or more, preferably 3 to 20 atomic%, and the remainder can be replaced by Fe. Further, when B exceeds 12 atomic%, R ₂
(FeCo) It is not preferable because a B-rich phase, a Fe-B compound, and the like are present in excess in addition to the ₁₄ B phase.

Manufacturing method of alloy powder In order to obtain an alloy powder consisting mostly of the R ₂ Fe ₁₄ B phase by melting and pulverizing, Co, Fe , B
R and other metals or their alloys are melt-produced to achieve the desired composition, and then pulverized for 2 to 2
Make a powder with an average particle size of 00 μm. In addition, a hydrogen-containing disintegration method can be used as a pulverizing method, and an atomizing method can be used to directly obtain a powder. Further, a solution treatment can be performed on the alloy mass produced by melting.

In order to obtain an R-rich alloy powder by the direct reduction diffusion method, at least one kind of metal powder and / or oxide powder composed of iron powder, cobalt powder, ferroboron powder, rare earth oxide powder and the like is used. The powder is selected so as to have a rare earth element content ratio corresponding to the rare earth element type and the amount of the target composition. Further, metal Ca or CaH ₂ is added to the raw material powder at a stoichiometric requirement of 1.1 to 1.1 for the reduction of the rare earth oxide powder.
~ 4.0 times (weight ratio) mixed, 900 ° C in an inert gas atmosphere
By heating to 1200 ° C and throwing the obtained reaction product into water to remove reaction by-products, coarse pulverization is unnecessary.
A powder having an average particle size of 200200 μm is obtained.

[0022] The intermetallic compound powder by alloy powder and a direct reduction diffusion process consisting of the required main phase by blending dissolution and powdering method of the alloy powder, 60 to 97: blended at a ratio of 40 to 3, depending on the magnet properties Alloy powders having a plurality of different compositions can be obtained. The R-Fe-B raw material powder for R-Fe-B permanent magnet according to the present invention has an excellent oxygen-containing content of 2000 ppm or less, exhibiting excellent properties. When using the obtained powder as it is,
If the particle size of the alloy powder is too large, the magnetic properties of the permanent magnet, especially high coercive force, cannot be obtained, and if the average particle size is less than 1 μm, the process of producing the permanent magnet, namely, press molding,
The average particle size of 1 to 80 μm is preferable because oxidization in the sintering and aging processes is remarkable and excellent magnetic characteristics cannot be obtained.In order to obtain excellent magnetic characteristics, the average particle size is 2 μm.
An alloy powder of 1010 μm is desirable.

Further, in order to obtain an excellent R-Fe-B permanent magnet having both a high residual magnetic flux density and a high coercive force by using the obtained alloy powder, the compounded raw material powder is required to have R12 atomic% or less. 25 atom%, B4 atom% ~ 10 atom%, Co0.1 atom% ~ 10 atom
%, A composition of 68 atomic% to 80 atomic% of Fe is preferable. Further, an alloy powder having a blended R ₂ Fe ₁₄ B phase as a main phase and / or R ₃
An intermetallic compound phase of Co or Fe and R including a Co phase and R ₂ (FeC
o) In an intermetallic compound powder composed of ₁₄ B phase etc., Cu 3.5 atomic% or less, S2.5 atomic% or less, Ti 4.5 atomic% or less, Si 15 atomic% or less, V9.5 atomic% or less, Nb 12.5 atomic % At most, Ta10.5 at% or less, Cr8.5 at% or less, Mo9.5 at% or less, W9.5 at% or less, Mn3.5 at% or less, Al9.5 at% or less, Sb2.5 at% Below, Ge7 atomic% or less, Sn3.5 atomic% or less, Zr5.5 atomic% or less, Hf5.5 atomic% or less, Ca8.5 atomic% or less, Mg8.5 atomic% or less, Sr7.0 atomic% or less, Ba7 By adding and containing at least one of 0.0 atomic% or less and Be 7.0 atomic% or less, it becomes possible to increase the coercive force, increase the corrosion resistance, and improve the temperature characteristics of the obtained permanent magnet.

When the composition of the permanent magnet produced by using the alloy powder according to the present invention is R11 atomic% to 25 atomic%, B4 atomic% to 10 atomic%, Co 30 atomic% or less, Fe 66 atomic% to 82 atomic%, The obtained magnetic anisotropic permanent magnet has a coercive force _i H _C ≧ 5 kOe, (BH) max
It shows magnetic characteristics of ≧ 20 MGOe, and the temperature coefficient of residual magnetic flux density is 0.1% / ° C. or less, and excellent characteristics are obtained. 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%, Fe66 atom% to 82 atom%, Co20 atom %, The most excellent magnetic properties are exhibited. Particularly, when the light rare earth metal is Nd, Pr, or Dy, the maximum value of (BH) max reaches 40 MGOe or more.

[0025]

EXAMPLES Example 1 Raw materials obtained by the dissolution / pulverization method of the main phase system were high- purity Nd, Dy,
B, Co, Fe, etc. were melted by high frequency in an argon atmosphere, and the obtained alloy lump was roughly pulverized by a jaw crusher or the like to obtain an alloy powder having an average particle size of about 15 μm. The obtained powder was composed of 9.5 atomic% of Nd, 0.1 atomic% of Pr, 2.3 atomic% of Dy, 5.9 atomic% of B, 1.0 atomic% of Co, and the balance of Fe, with an oxygen content of 850 ppm. Was.

The raw material of the R-rich intermetallic compound powder is obtained by a direct reduction diffusion method using rare earth oxides such as Nd ₂ O ₃ and Dy ₂ O ₃ ;
Fe-B powder, Co powder, using Fe powder as the starting material mixed in the required ratio, this metal Ca, a mixture of a predetermined amount of anhydrous CaCl _2, was charged into the stainless steel container, in an Ar gas stream After reducing and diffusing Ca under the condition of 1000 ° C × 3 hours, cooling, washing with water, replacing with water, heating and drying in vacuum, Nd 25.2 atomic%, Pr 1.2 atomic%, D
An alloy powder composed of 0.5 atomic% of y, 10 atomic% of B, 7.7 atomic% of Co, and the balance Fe was obtained.

In the observation of EPMA and the like, the Nd ₃ Co phase (a part of Co
) And intermetallic compounds such as the main phase R ₂ Fe ₁₇ phase (a part of Fe was substituted by Co) and R ₂ (FeCo) ₁₄ B phase were observed, and the oxygen content was 1000 ppm.

Using these two raw material powders, 80% of the main phase alloy powder and 20% of the R-rich intermetallic compound powder were blended and mixed, and 12.2 atomic% of Nd, 0.2 atomic% of Pr, and 0.2% of Dy2. 0 atomic%, B6.6
A raw material powder composed of atomic%, 2.1 atomic% of Co, and the balance Fe was used as a starting material for the magnet. This raw material powder is
Finely pulverized to about 3μm with a pulverizer, and the obtained fine powder is molded
Charge and orient in a magnetic field of about 10 kOe, perpendicular to the magnetic field
Molded at a pressure of about 1.5 ton / cm ^2, molding of 15 mm × 20 mm × 8 mm
Created body. Argon atmosphere of 1090 ℃ × 3 hours
It was sintered under medium conditions and subjected to aging treatment at 530 ° C. for 2 hours. The magnet properties of the obtained test piece were Br = 12.2 kG, (BH) max = 34.9 M
GOe, iHc = 22.5 kOe, and the oxygen content was 4600 ppm.

COMPARATIVE EXAMPLE 1 High-purity Nd metal, Dy metal, Co metal, B and Fe were melted by high frequency, and Nd was 12.2 atomic%, Pr 0.2 atomic%, Dy 2.0 atomic%, and B6.6 atomic.
%, Co atomic% of 2.1 and the balance of Fe were prepared. EPM
In the observation of A and the like, it was observed that the Nd ₃ Co phase and the Nd-rich phase (Nd = about 95%) were unevenly distributed. Using this starting material powder,
The magnet properties of a test piece obtained by preparing a magnet in the same process as in Example 1 were Br = 11.8 kG, (BH) max = 33.2 MGOe, iHc = 22 kOe, and the oxygen content was 5400 ppm.

[0030]

According to the present invention, an alloy powder having a composition close to the R ₂ Fe ₁₄ B phase having a small R-rich phase is prepared by a melting and pulverizing method.
The more direct reduction diffusion method, the alloy particles by the addition of R-rich intermetallic compound powder of Co element R ₃ Co phase or the R ₃ Co phase R ₂ a portion substituted with Fe in the Co (FeCo) By preparing an intermetallic compound alloy powder consisting of ₁₇ phases and other intermetallic compound phases such as R ₂ (FeCo) ₁₄ B phase, by mixing both,
It is possible to easily obtain a predetermined magnet composition alloy powder having a low oxygen content and high magnetic properties. Further, the present invention is to change the rare earth element species and the amount thereof according to the required several kinds of magnet properties, when producing a raw material alloy powder for R-Fe-B-based permanent magnet composed of a plurality of kinds of compositions, For example, one kind of main phase alloy powder having a required composition, and a plurality of kinds of intermetallic compound powders produced by changing the rare earth element content ratio of the intermetallic compound according to the rare earth element species and the amount of the target composition. By blending, it is possible to easily obtain an alloy powder having a plurality of compositions according to the required magnet properties.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C22C 38/00 303 B22F 1/00

Claims (2)

(57) [Claims] 1. R (where R is at least one of rare earth elements including Y) 11 at% to 13 at%, B 4 at% to 12 at%, balance
R ₂ composed of Fe and unavoidable impurities and dissolved and powdered
An alloy powder having a Fe ₁₄ B phase as a main phase is 60 wt% to 97 wt%, and R (however, R
Is at least one of the rare earth elements containing Y) 13 atomic% to 45 atomic%
Atomic%, B12 atomic% or less, the balance consists of Co (however, part or most of Co can be replaced by Fe) and unavoidable impurities, and by direct reduction diffusion method, Co or Fe and R containing R ₃ Co phase
And an intermetallic compound phase comprising 40 wt% to 3 wt% of an intermetallic compound phase (however, part or most of Co can be replaced by Fe) and R ₂ (FeCo) ₁₄ B phase, and R-Fe-B A method for producing a raw material powder for an R-Fe-B-based permanent magnet, wherein the raw material powder is blended with a required composition of the R-Fe-B-based permanent magnet. 2. R (where R is at least one of the rare earth elements containing Y) 11 at% to 13 at%, B 4 at% to 12 at%, and Co
10 atomic% or less, and the balance Fe and unavoidable impurities, that by the dissolution and powdering method R ₂ Fe ₁₄ B phase or R ₂ (Fe Co) ₁₄ B phase alloy powder 60 wt% of the main phase of ～97Wt% And R (where R is at least one of the rare earth elements including Y) 13 atom% to 45 atom%, B 12 atom%
Hereinafter, the balance consists of Co (however, a part or most of Co can be replaced by Fe) and unavoidable impurities, and the intermetallic compound phase of Co or Fe and R including R ₃ Co phase by direct reduction diffusion method.
(However, part or most of Co can be replaced with Fe) and R
₂ (FeCo) ₁₄ B phase intermetallic compound powder 40 wt% to 3 wt%
And a compound having the required composition of R-Fe-B-based permanent magnets.