JP2623731B2 - Manufacturing method of rare earth-Fe-B based anisotropic permanent magnet - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a rare earth element (hereinafter, referred to as R) -Fe-B permanent magnet containing Y having magnetic anisotropy. .

[Conventional technology]

Generally, R-Fe-B permanent magnets are known as magnets having excellent magnetic properties.

The structure of the R-Fe-B-based permanent magnet includes a main phase of R ₂ Fe ₁₄ B intermetallic compound phase (hereinafter, referred to as R ₂ Fe ₁₄ B phase) which is a ferromagnetic phase and has a tetragonal structure. R-rich phase and B-rich
It is composed of equivalents.

Among the R-Fe-B permanent magnets, there are the following magnets having magnetic anisotropy.

An anisotropic permanent magnet (hereinafter referred to as a sintered magnet) characterized by a sintered body by a powder metallurgy method described in JP-A-59-460008 is manufactured as follows.

First, an ingot of an R-Fe-B alloy is pulverized by a mechanical method to obtain a fine powder having an average particle diameter of about 3 μm, and the fine powder is formed in a magnetic field to obtain a green compact. Next, the green compact is heated from room temperature in a vacuum or a non-oxidizing gas, sintered at a temperature of 900 to 1200 ° C., and further subjected to a heat treatment at an appropriate temperature as required, and then cooled. It is manufactured by: The magnetic properties of the above sintered magnet are BH _max = 30MGO
Indicates a value greater than or equal to e.

The average particle diameter of the main phase R ₂ Fe ₁₄ B phase is controlled to several μm to 20 μm in order to increase the coercive force.

Next, the anisotropic permanent magnet described in JP-A-60-100402 is manufactured as follows.

An amorphous ribbon is obtained by rapidly solidifying the R-Fe-B alloy in the molten state, and the amorphous ribbon is heated to a temperature of 700 ° C or higher, hot-pressed, and further plastically processed to become anisotropic. , BH _max = about 30 MGOe. And the organization is the prime minister R ₂
Fe ₁₄ B phase and R-ri existing at the grain boundary around R ₂ Fe ₁₄ B phase
It consists of ch phase. The average particle size of the R ₂ Fe ₁₄ B phase is controlled to several hundred nm in order to increase the coercive force.

[Problems to be solved by the invention]

The anisotropic sintered magnet described in JP-A-59-460008 has an average crystal grain size of the main phase R ₂ Fe ₁₄ B phase of several μm.
Since it is necessary to control the average particle size to 3 to 4 μm in consideration of the grain growth of the R ₂ Fe ₁₄ B phase in the sintering process,
m, which is manufactured by sintering a compact formed by press molding in a magnetic field using the fine powder mechanically pulverized to m, but the average powder having the above average particle diameter: 3 to 4 μm In order to become very active, the fine powder is oxidized in the step of filling in a magnetic field press molding machine and press molding in a magnetic field, and the anisotropic sintered magnet obtained by press molding in the magnetic field is subjected to O ₂ etc. Impurities are mixed, and the magnetic characteristics are greatly reduced. For example, even if an anisotropic sintered magnet without the above-mentioned oxide contamination is obtained, the anisotropic sintered magnet obtained by this method has a greatly reduced magnetic property when the thickness is reduced to 3 mm or less. There was a problem.

Further, the anisotropic magnet described in the above-mentioned Japanese Patent Application Laid-Open No. 60-100402 is characterized in that an amorphous ribbon is produced by rapidly cooling a molten metal obtained by melting an R-Fe-B alloy ingot. Is hot pressed at a temperature of 700 ° C. or higher to produce an isotropic magnet, and then plastically processed at the same temperature. The process of obtaining the amorphous ribbon has a problem in that the yield of the material is low and the process is complicated because the isotropic magnet is cut out and subjected to plastic working.

[Means for solving the problem]

Therefore, the present inventors differ from the conventional sintering method, in which impurities such as O ₂ are liable to be mixed, and differ from the conventional ultra-quenching method in which the yield from the raw material alloy is low. As a result of research on obtaining an R-Fe-B-based anisotropic magnet which has a good yield and does not deteriorate magnetic properties even when it is thin, an R-Fe-B-based anisotropic permanent magnet was obtained. In, the organization is R ₂ Fe ₁₄
The recrystallized structure having the B phase as a main phase is subjected to compression plastic working such as pressing or rolling to have a texture in which individual crystal grains are oriented in the crystallographic C-axis direction (hereinafter referred to as a recrystallized rolled structure). The R-Fe-B anisotropic magnet has been found to solve the above-mentioned problems and exhibit excellent magnetic properties.

The present invention was made based on these findings, in of H ₂ gas atmosphere or H ₂ in a mixed atmosphere of a gas and an inert gas, temperature: 500 to 1000 ° C. and held the ingot above alloy, H ₂ is absorbed into the powder, the homogenized ingot or the homogenized powder, and the H ₂ gas pressure is 1 × 10 ⁻¹ Torr or less in a vacuum atmosphere or H _2.
Gas partial pressure: 1 × 10 ^-1 Torr or less until it becomes an inert gas atmosphere.Temperature: De-H ₂ treatment at 500 to 1000 ° C. and then cooling or heat treatment at a temperature of 300 to 1000 ° C. and R-Fe-B alloy material (hereinafter, referred to as H ₂ treated) characterized by R-Fe-B based anisotropic permanent magnet manufacturing method of the bulk state by plastic working at a temperature 600 to 900 ° C. Things.

In the R-Fe-B-based anisotropic permanent magnet produced by the method of the present invention, in the structure thereof, the R ₂ Fe ₁₄ B phase has an average crystal grain size of 0.05 to 50 μm, preferably close to a single domain grain size.
Is about 0.3 [mu] m, and a recrystallized rolled structure with a texture oriented in the crystallographic C-axis direction of the R ₂ Fe ₁₄ B phase, O ₂
Since the density ratio is almost 100% without impurities, etc., the magnetic characteristics are very stable, and the magnetic characteristics are excellent even in a thin shape with a thickness of 3 mm or less. It has anisotropy.

The structures of the R-Fe-B-based anisotropic permanent magnet obtained by the production method of the present invention and a conventional R-Fe-B-based permanent magnet will be compared. FIG. 1 (a) shows the recrystallized rolled structure of the R-Fe-B based anisotropic permanent magnet obtained by the production method of the present invention, and FIG. 1 (b) shows the structure of a conventional sintered magnet. FIG. 1 (c) shows the structure of a permanent magnet obtained by hot pressing and plastic working a conventional amorphous ribbon. The R-Fe-B-based anisotropic permanent magnet obtained by the production method of the present invention shown in FIG. 1 (a) has an average crystal grain size of 0.05 to 50 μm, preferably a single magnetic domain grain size of 0.05 μm which is close to 0.3 μm. ~ 10 μm R ₂ Fe ₁₄
A crystal grain 1 ″ obtained by rolling the recrystallized grains of the B phase is present on almost one surface, and constitutes a recrystallized rolled structure, in which the R-rich phase 2 precipitates at some grain boundaries due to the alloy composition. there contrast, conventional sintered magnet of FIG. 1 (b) has an average grain size:. main phase 1 part to about 10μm to exist B-rich phase 3, R ₂ Fe ₁₄ B An R-rich phase 2 is present in each crystal grain of phase 1 at the surrounding grain boundary. The permanent magnet obtained by hot pressing and plastic working the conventional amorphous ribbon shown in FIG. Crystal grain size: about 100nm R ₂ Fe
_{This is a structure in which the 14} B phase 1 is present and the R-rich phase 2 is present in the surrounding grain boundary portion in each crystal grain of the R ₂ Fe ₁₄ B phase 1. As described above, in each of the conventional permanent magnets, in each crystal grain of the R ₂ Fe ₁₄ B phase, the R-rich phase is present at the surrounding grain boundary portion, whereas the production method of the present invention is used. The R-Fe-B-based anisotropic permanent magnet has an R-rich phase precipitated only in a part of the grain boundary of the main phase, and has a completely different structure. For this reason, excellent magnetic characteristics that solve the above problems are shown.

In general, as a method of obtaining a recrystallized structure, after including many dislocations and strains such as vacancies in the material by plastic working such as rolling, heat treatment is performed at an appropriate temperature to generate a large number of recrystallized crystals, a method of growing is known, in this invention, by occluding of H ₂ to the alloy ingot or powder, prompting the phase transformation of the main phase, to perform the de-H ₂ treatment at an appropriate temperature Thus, a method of generating and growing recrystallized grains of the main phase and obtaining a recrystallized texture with few impurities and without distortion (hereinafter referred to as an H ₂ treatment method) was employed.

The method for producing an R-Fe-B-based anisotropic permanent magnet of the present invention will be compared with a conventional method for producing an R-Fe-B-based permanent magnet.
FIG. 2 (a) shows a method for producing an R-Fe-B based anisotropic permanent magnet of the present invention, FIG. 2 (b) shows a conventional method for producing a sintered magnet, and FIG. c) shows a conventional method for producing a permanent magnet obtained by hot-pressing and plastically processing an amorphous ribbon. As is apparent from FIG. 2, the conventional manufacturing method uses a sintering method or a super-quenching method, whereas the manufacturing method of the R-Fe-B-based anisotropic permanent magnet of the present invention is as follows. in that H ₂ is used treatment method, it can be seen that the conventional manufacturing method which is quite different from the new production method.

The R-Fe-B-based anisotropic permanent magnet of the present invention and a method for producing the same will be described in more detail.

First, the R-Fe-B-based alloy as a raw material will be described.

The R-Fe-B-based alloy as a raw material includes: 1) an ingot of an R-Fe-B-based alloy; 2) a powder obtained by pulverizing an ingot of an R-Fe-B-based alloy; R- obtained by the diffusion method, etc.
Fe-B-based alloy powder (hereinafter, referred to as powder) 3) Temperature: Ingot of the above-mentioned R-Fe-B-based alloy which has been subjected to homogenization treatment while being maintained at 600 to 1200 ° C (hereinafter, referred to as homogenization treatment ingot). 4) The powder obtained by pulverizing the above-mentioned homogenized ingot or the powder of the R-Fe-B-based alloy according to the above 2) which has been homogenized while maintaining the temperature at 600 to 1200 ° C. Powder). The homogenization treatment may be performed in a vacuum or an inert gas atmosphere while maintaining the temperature at a constant temperature within a range of 600 to 1200 ° C., and the temperature: 600 to 12 ° C.
The temperature may be raised, lowered, or a combination thereof within a temperature range of 00 ° C.

It is better to use as a homogenized treatment ingot than to use it as an ingot, and it is better to use it as a homogenized treatment powder than to use it as a powder, because of the R-Fe-B anisotropic permanent magnet obtained by the production method of the present invention. Magnetic properties are further improved.

The reason is that the metal structure of the R-Fe-B-based alloy ingot obtained by casting, the powder obtained by crushing the cast ingot, or the R-Fe-B-based alloy powder obtained by the conventional Ca reduction method or the like is as follows. mainly main phase: R ₂ Fe ₁₄ and a B-phase and R-rich phase, but the R ₂ Fe ₁₄ B phase, alpha-Fe
Phase, R ₂ Fe ₁₇ phase and other non-equilibrium structures are often precipitated, and the above-mentioned non-equilibrium structure can be obtained by performing a homogenization treatment rather than using an ingot or powder having the above-mentioned non-equilibrium structure as a raw material. It is better to use a homogenized ingot or a homogenized powder consisting essentially of the main phase: R ₂ Fe ₁₄ B phase and the R-rich phase as a raw material.
The magnetic properties of the system anisotropic permanent magnet are greatly improved.

When an ingot or a homogenized ingot of the above alloy is used as a raw material, a decrease in magnetic properties due to oxidation can be suppressed as compared with the case where a powder or a homogenized powder is used as a raw material.

In particular, the composition of the R-Fe-B-based alloy is expressed by 11.8 ≦ X ≦ 15 in the vicinity of the composition of the main phase: R ₂ Fe ₁₄ B phase, that is, in R _x (Fe, B) _100-X in atomic percentage. It is preferable to use a homogenized ingot as a raw material for alloys having a certain composition.

However, for an alloy having a composition represented by X <11.8 or X> 15 in R _x (Fe, B) _100-X in atomic percentage, depending on the composition of the alloy, an ingot or a homogenized ingot is used as a raw material. In some cases, the use of powder or homogenized powder as a raw material may improve magnetic properties. In comparison, a composition having a small amount of R component and B component tends to have a good alloy shape of a raw material, and a composition having a large amount of R component and B component tends to have a good alloy shape of a raw material.

The method for producing a rare-earth-Fe-B-based anisotropic permanent magnet of the present invention is characterized in that, in a H ₂ gas atmosphere or a mixed atmosphere of H ₂ gas and an inert gas, the temperature is maintained at 500 to 1000 ° C. H ₂ is absorbed into the ingot, powder, homogenized ingot or homogenized powder of H ₂ , and the H ₂ gas pressure is 1 × 10 ⁻¹ Torr or less in a vacuum atmosphere or the H ₂ gas partial pressure is 1 × 10 ⁻¹ Torr or less. H ₂ treatment at 500 to 1000 ° C. until an inert gas atmosphere is reached, then cool or heat treat at 300 to 1000 ° C. to obtain an H ₂ treated body at a temperature of 600 to 900 ° C. It is characterized in that it is made into a bulk state by plastic working, but the reason for selecting H ₂ gas or an inert gas containing H ₂ gas as the atmosphere in the above process is only to remove strain and prevent oxidation. Not only, but also ingots, powders and homogenized R-Fe-B alloys as raw materials Brought tissue changes sense ingot or homogenized powder is because it can be a crystalline structure with magnetic properties which anisotropic permanent magnet obtained has excellent in process of the present invention. Even if the above holding is performed only in other inert gas or in vacuum,
This recrystallized texture cannot be obtained.

The above “temperature: maintained at 500 to 1000 ° C.” means the above temperature: 5
In addition to maintaining a constant temperature in the range of 00 to 1000 ° C,
The temperature may be increased or decreased within the above temperature range. The temperature increase or decrease may be linearly increased or decreased, or may be curved or decreased. Further, the temperature may be changed within an arbitrary range of the above-mentioned temperature: 500 to 1000 ° C., that is, a combination of a temperature rise, a constant temperature hold, and a temperature drop.

The room temperature Temperature: middle atmosphere heated to 500 to 1000 ° C. is necessarily good even without H ₂ gas, an inert gas such as another Ar, or may be a vacuum, but preferably it is H ₂ gas. When the temperature is maintained at 500 to 1000 ° C., H ₂ gas is essential. After completion of the above process, H ₂ gas pressure: 1 ×
10 ^-1 Torr or less in a vacuum atmosphere or H ₂ gas partial pressure: 1 × 10 ^-1 To
Temperature until inert gas atmosphere below rr: 500-1000 ℃
And the above-mentioned H ₂ removal treatment is performed. In this the step, in H ₂ processed
If H ₂ remains, high coercive force cannot be obtained. This pattern of de H ₂ process, the above process as well as the above temperature: 500-1000
In addition to maintaining a constant temperature in the range of ° C., the temperature may be increased or decreased linearly or in a curve in the above temperature range, and further, the above temperature: in the range of 500 to 1000 ° C., The temperature may be changed by any combination of temperature increase, constant temperature hold, and temperature decrease. The temperature range of the process of the above step are the same, in always H ₂ gas atmosphere or
The temperature maintained in the mixed atmosphere of the H ₂ gas and the inert gas may not be de-H ₂ by maintaining the temperature, for example, the temperature may be maintained in the H ₂ gas atmosphere or the mixed atmosphere of the H ₂ gas and the inert gas. The temperature may be further raised and lowered from the temperature to de-H _2, but the resulting anisotropic permanent magnet has no grain growth or the like of recrystallized grains, so that a recrystallized rolled structure having a high coercive force is obtained. it is preferable to perform the de-H ₂ at a temperature which was kept in a mixed atmosphere in H ₂ gas atmosphere or H ₂ gas and an inert gas.

After the above steps are completed, the above steps are repeated.
May be performed.

After the H ₂ removal treatment, in the above-described step, cooling is performed with an inert gas such as Ar, or heat treatment is performed at a constant temperature in a vacuum or in an inert gas during cooling. This heat treatment is performed as needed. The heat treatment temperature is 300-100
The temperature range is 0 ° C, preferably 550-700 ° C. Such heat treatment, after cooling to room temperature with the inert gas,
The heating may be performed again in vacuum or in an inert gas, and may be performed not only once but also two or more times. Above
It is desirable that the cooling after H ₂ conversion and after the heat treatment be as fast as possible.

The H ₂ treatment body is a powder or lump, may be used as it is, or may be all lightly crushed into powder. The above H ₂ treated it can also be a powder subjected to the magnet powder of an R-Fe-B based.

The plastic working in the above step is performed at a temperature of 600 to 900 ° C. By applying the plastic working, and the density ratio of the above H ₂ processed to a bulk state of almost 100%, the texture oriented the recrystallized structure of the H ₂ processed in crystallographic C axis Recrystallized rolled structure.

First, filling the H ₂ processed into a can. The H ₂ treatment body, and densely packed by adding compression or vibration, to seal the opening of the can in a vacuum, to prepare a canning packing. Here, to seal the opening of the can is to prevent the order anisotropic magnet of the present invention to prevent the oxidation, the H ₂ processed during plastic working from flowing out from the can. If the plastic processing of the can-enclosed filling is carried out in a vacuum or in an inert gas atmosphere, it is not always necessary to enclose the opening of the can. The body is also called the can-enclosed filling.

FIG. 3 is a schematic sectional view of the can-enclosed filling. The third above
In the figure, 8 is a can, 4 is a powder of the H ₂ treated body, 4 ′
Is a mass of H ₂ processed. 'Be included, the masses 4' de H ₂ treated H ₂ treatment material packed in the can 8 is comprised primarily of the powder 4 is the mass 4 is collapsed because it is H ₂ treatment Easy and no problem in plastic working. Reference numeral 7 in FIG. 3 indicates a can-enclosed filling.

FIG. 4 is a schematic diagram showing a state in which the can-enclosed filling 7 is plastically processed by press compression, and FIG. 5 shows a state in which the can-enclosed filling 7 is plastically processed by roll rolling. FIG. In FIG. 4, 5 indicates a press punch, and in FIG. 5, 6 indicates a rolling roll. As shown in FIGS. 4 and 5, the inside of the can
H ₂ processed becomes a bulk material densified density ratio up to nearly 100% by plastic working, further of H ₂ processed in the above R ₂
The recrystallized grains of the Fe ₁₄ B phase are oriented in the crystallographic C-axis direction,
It becomes a recrystallized rolled structure having a texture and becomes an anisotropic permanent magnet having excellent magnetic properties.

Further, the plastic working in the above-mentioned step is not limited to being performed using the above-mentioned can-enclosed filling, and the plastic working may be performed after the hot pressing step in the conventional method. By hot pressing of a conventional method, the H ₂ treatment body becomes bulk material densified density ratio up to nearly 100%, by subsequently performing plastic working, H ₂ process of this bulk H ₂
The recrystallized grains of the R ₂ Fe ₁₄ B phase in the treated body are oriented in the crystallographic C-axis direction, forming a recrystallized rolled structure having a texture, and an anisotropic permanent material having excellent magnetic properties. Become a magnet.

The strain rate during the plastic working is preferably about 10 ^-1 to 10 ^-3 S ^-1 , and the crystallographic C-axis direction of the recrystallized grains of the main phase is oriented. The rolling ratio is preferably 60% or more, and in the case of press working, the compression ratio is preferably 60% or more. Here, the aforementioned rolling ratio, when the thickness of the material before rolling h _0, the thickness of the material after rolling was is h, the rolling rate _{= {(h 0 -h) /} h 0} × 100 ( %), And the above-mentioned compression ratio is the thickness of the material before pressing.
Assuming that H ₀ is the thickness of the object after the press working, H is expressed as follows: Compressibility = {(H ₀ −H) / H ₀ } × 100 (%)

Next, in the method for producing a rare earth-Fe-B based anisotropic permanent magnet of the present invention, the structural change of the R-Fe-B based alloy in each production step will be described.

The structure of the alloy ingot obtained by melting and casting is shown in FIG. 6 (a), and the structure of the alloy ingot obtained by homogenizing the cast ingot is shown in FIG. 6 (b).
Is shown in 6 (a) and 6 (b), 1 is a main phase of R ₂ Fe ₁₄ B phase, 2 is an R-rich phase, 3 ′ is a non-equilibrium such as α-Fe phase and R ₂ Fe ₁₇ phase. Indicates a phase. By performing the homogenization process, the R ₂ Fe ₁₄ B shown in FIG.
Present in phase 1. alpha-Fe phase, disappeared nonequilibrium phase 3 ', such as R ₂ Fe ₁₇ phase, substantially R ₂ Fe as the FIG. 6 (b)
₁₄ Equilibrium phase of B phase 1 and R-rich phase 2. Next, the above H ₂
By performing the treatment, the structure of FIG. 6 (b) undergoes a phase transformation, and then a recrystallized R ₂ Fe ₁₄ B phase 1 ′ is generated as shown in FIG. 6 (c). It becomes the H ₂ treatment having a texture of growing Figure 6 (d) R ₂ Fe ₁₄ B phase 1 was recrystallized as shown in '. R-rich phase 2
It is present in some grain boundaries of the recrystallized R ₂ Fe ₁₄ B phase 1 ′.
By performing the plastic working, the recrystallized structure becomes a recrystallized rolled structure composed of crystal grains 1 ″ oriented in the crystallographic C-axis direction as shown in FIG. 6 (e). However, the R-rich phase 2 exists in some grain boundaries of the crystal grains 1 ″ obtained by rolling the recrystallized R ₂ Fe ₁₄ B phase 1 ′.
The arrows in FIGS. 6 (d) and (e) indicate the recrystallized R ₂
This shows the crystallographic C-axis direction of the Fe ₁₄ B phase 1 ′ and the crystal grains 1 ″ obtained by rolling the Fe ₁₄ B phase 1 ′.

The reason why the production method of the present invention and the crystal grain size of the R-Fe-B-based anisotropic permanent magnet produced by the production method are limited as described above will be described.

(1) Crystal grain size of recrystallized rolled structure If the average crystal grain size is smaller than 0.05 μm, magnetization becomes difficult, and grain control becomes difficult, which is not practical.
If it is larger than 50 μm, only a low coercive force is exhibited. Therefore, the average crystal grain size of the recrystallized rolled structure is set to 0.05 to 50 μm. Preferably, it is close to the single domain grain size of the R ₂ Fe ₁₄ B phase
More excellent magnetic properties can be obtained when the thickness is in the range of 0.05 to 10 μm.

(2) Homogenization treatment The use of a homogenized ingot or a homogenized powder further improves the magnetic properties. If the temperature of the homogenization treatment is lower than 600 ° C., it takes a long time for the homogenization treatment, resulting in poor industrial productivity. On the other hand, if the temperature exceeds 1200 ° C., the ingot or the powder is undesirably melted. Therefore, the homogenization temperature was set at 600 to 1200 ° C.

(3) H ₂ treatment The atmosphere in the above process is such that the H ₂ gas pressure or H ₂ gas partial pressure is at least 10 Torr or more in an H ₂ gas atmosphere or a mixed atmosphere of H ₂ gas and an inert gas. It is preferable to carry out under conditions.

If the above H ₂ gas pressure or H ₂ gas partial pressure is less than 10 Torr,
The R-Fe-B alloy ingot as a raw material powder, since H ₂ is not occluded until homogenization ingot or homogenized powder is sufficiently to tissue changes is not preferable. Further, when the H ₂ gas pressure or the H ₂ gas partial pressure is higher than 760 Torr, that is, when the pressure is higher than the atmospheric pressure, it takes a long time to remove the H ₂ gas, which is not industrial.

If the holding temperature in the H ₂ gas atmosphere or the mixed atmosphere of the H ₂ gas and the inert gas is lower than 500 ° C, the structural change of the above alloy cannot be sufficiently obtained, and when the holding temperature is higher than 1000 ° C, the structural change is excessively advanced. to recrystallized grains cause grain growth, since the coercive force is reduced, H ₂ occlusion treatment temperature was defined as 500 to 1000 ° C..

De H ₂ treatment temperature described above, is less than 500 ° C., H ₂ and H ₂ gas pressure or partial pressure to 1 × 10 H ₂ processed even in the ^-5 Torr or less
Is not preferable because high coercive force cannot be obtained.
If the temperature exceeds 00 ° C., the H ₂ treated bodies will adhere to each other,
Since the recrystallized grains grow and the coercive force decreases, the temperature for the H ₂ removal treatment is set to 500 to 1000 ° C.

Further, the de-H ₂ treatment in this step aims at almost complete de-H ₂ conversion of the H ₂ treated body. If the H ₂ gas pressure or partial pressure is higher than 1 × 10 ⁻¹ Torr, Since the removal of H ₂ becomes insufficient and a high coercive force cannot be obtained, the H ₂ gas pressure or partial pressure is set to 1 × 10 ⁻¹ Torr or less.

(4) Plastic working If the plastic working temperature is lower than 600 ° C., the H ₂ treated body is not densified. If the plastic working temperature is higher than 900 ° C., the recrystallized grains will grow vigorously, making grain control difficult. It was determined to be 600-900 ° C.

(5) the magnetic properties are further improved when subjected to thermal treatment the H ₂ treatment and after the plastic working after the heat treatment. However, when the heat treatment temperature is lower than 300 ° C., the effect of the heat treatment hardly appears, and when the heat treatment temperature is higher than 1000 ° C., the grain growth of the recrystallized grains becomes intense and grain control becomes difficult, so the heat treatment temperature is set to 300 to 1000 ° C. Was.

The R-Fe-B produced by the production method of the present invention
Part of Fe of the system anisotropic permanent magnet is M, (M is Co, Ru, Rh, I
r, Os, Pd, Pt, Re, Ni, V, Nb, Ta, Cu, Cr, Mn, Mo, W, Ti, Al, Ga, I
n, Zr, Hf) may be substituted with a small amount of one or more of them. A part of B is A, (A is N, P, S, F, Si, C, Ge, S
n, Zn, Sb, Bi) may be substituted with a small amount of one or more of them.

〔Example〕

Next, the present invention will be specifically described based on embodiments.

Examples 1-4 and Comparative Examples 1-4 Melting and casting were performed using a plasma arc furnace, and Nd was
An alloy ingot containing _14.5 Fe _77.5 B _8.0 as a main component was manufactured. Put the above ingot in a heat treatment furnace, 1 × 10 ^-5 Torr
After evacuating to a vacuum, a homogenization treatment was performed at a temperature of 1000 ° C. for 40 hours, then the furnace temperature was lowered to 850 ° C., and H ₂ gas was introduced into the heat treatment furnace and the furnace atmosphere was To
H ₂ gas atmosphere, H ₂ gas pressure: 1 in the above furnace atmosphere
atm, temperature: 850 ° C., 10 hours and H ₂ occlusion treatment under the conditions of holding a further exhaust while maintaining the furnace temperature above 850 ° C. 1
After a certain time, a vacuum of 1.0 × 10 ⁻⁵ Torr was applied to remove H ₂ , followed by quenching by flowing Ar gas into the furnace.

The H ₂ storage processing and de H ₂ treated alloy ingot, since the brittle and disintegrated in the above Ar atmosphere H ₂
And processed, the H ₂ treatment body, vertical: 30 mm × horizontal: 30 mm × height: was filled into a stainless steel can having an inner dimension of 11 mm, sealed by electron beam welding the opening of the can in a vacuum And
A can-filled packing was made. Temperature of the above can-filled packing body: 700
Example 1 finally shown in Table 1 while maintaining at
Roll-rolling was performed until the thickness was as shown in Nos. 1 to 4 to produce a thin anisotropic magnet of the present invention. Each of the anisotropic magnets of the present invention of Examples 1 to 4 had a recrystallized rolled structure having a texture in which the R ₂ Fe ₁₄ B phase was oriented in the C-axis direction.

On the other hand, for comparison, an alloy ingot having the same composition as that of the above-described embodiment mainly composed of Nd _14.5 Fe _77.5 B _8.0 in atomic% melted and cast using the above plasma arc furnace was mechanically pulverized in an inert gas atmosphere. A fine powder having an average particle size of 3.8 μm was produced. The fine powder is press-molded in a magnetic field to obtain green compacts having different thicknesses. Then, the green compact is sintered in an inert gas atmosphere to obtain a green compact as shown in Comparative Examples 1 to 4 in Table 1. A thin anisotropic magnet was made.

The magnetic properties of these thin anisotropic magnets were measured, and then the content of O ₂ contained in the thin anisotropic magnet was measured. The results are shown in Table 1.

From the results in Table 1, it can be seen that the R-Fe-B anisotropic magnet obtained by the production method of the present invention has a low O ₂ content, and the magnetic properties are not particularly changed by the thickness of the magnet. It can be seen that in the case of the comparative example, the O ₂ content is large, and particularly when the thickness is 3 mm or less, the magnetic properties are rapidly deteriorated.

Example 5 and Comparative Example 5 Melted and cast in a high frequency melting furnace, and Nd _13.6 Fe _80.6
Two alloy ingots having _B5.8 as a main component and weighing 500 g were produced. One of the two alloy ingots was placed in a heat treatment furnace in an Ar gas atmosphere, and the temperature was set to 1100.
At 20 ° C. for 20 hours, then lower the furnace temperature to 850 ° C., flow H ₂ gas into the heat treatment furnace, and change the furnace atmosphere to H ₂ gas atmosphere. H ₂ gas pressure at ambient: 1 atm, temperature: 850 ° C., 10 h H ₂ occludes treated with holding conditions, further the 850 ° C. the furnace temperature is performed 1 hour exhaust while maintaining a 1.0 × 10 ^-5 After reducing the pressure to Torr and removing H ₂ , the furnace was rapidly cooled by flowing Ar gas into the furnace.

Since the alloy ingot subjected to the H ₂ occlusion treatment and the de-H ₂ treatment is easily collapsed, the alloy ingot is crushed in the Ar atmosphere to form an H ₂ treated body, and the H ₂ treated body has a diameter of 46 mm × height. :
A copper can having an inner dimension of 50 mm was filled, and the opening of the can was covered with a copper lid to prepare a can-enclosed filling. While maintaining the above-mentioned can-enclosed filling at a temperature of 700 ° C., a press-compression process was performed in a vacuum of 1 × 10 ⁻⁴ Torr at a strain rate of 1 × 10 ⁻¹ S ⁻¹ and a compression ratio of 80%. And R-Fe-B based anisotropic magnets were manufactured.
The weight of the anisotropic magnet obtained from the alloy ingot as described above was 487 g when measured. The material yield by the manufacturing method of the present invention was calculated from the measured values of the weight of the alloy ingot and the weight of the anisotropic magnet, and the magnetic properties of the anisotropic magnet were measured. It was shown to.

On the other hand, for comparison, the other alloy ingot was subjected to single-roll ultra-quenching from a molten state to form an amorphous ribbon, and the amorphous ribbon was heated to a temperature of 730 ° C.
Was hot-pressed to produce an isotropic magnet, and then the above isotropic magnet was press-compressed at a temperature of 700 ° C. to produce an R—Fe—B-based anisotropic magnet.

When the weight of the R-Fe-B-based anisotropic magnet was measured, it was 320 g. The yield at this time was calculated, and the magnetic properties were measured. The results are shown in Table 2.

From the results in Table 2, the anisotropic magnet obtained by melting the R-Fe-B alloy ingot and hot pressing the amorphous ribbon obtained by quenching was obtained by the manufacturing method of the present invention. It can be seen that the magnetic properties are inferior to those of the anisotropic magnets, and that the yields of the materials are significantly different due to the difference in the manufacturing method.

As a result of X-ray diffraction of the anisotropic magnet of the present invention obtained in Example 5, the main diffraction line is indexed by the plane index of the Nd ₂ Fe ₁₄ B intermetallic compound having a tetragonal structure. Therefore, it was found that the Nd ₂ Fe ₁₄ B phase was the main phase. Further, from the difference in relative diffraction intensity, it was found that the crystallographic C axis of the main phase was oriented in the direction of press compression.

Next, the structure of the anisotropic magnet obtained in Example 5 was observed. FIG. 7 (a) is a photograph of a metallographic structure of the anisotropic magnet of the present invention taken by a transmission electron microscope, and FIG. 7 (b).
FIG. 3 is a schematic explanatory view of the metal structure photograph. 7 (a) and 7 (b), the anisotropic magnet of the present invention is approximately
It can be seen that the recrystallized grains of 0.3 μm have a recrystallized rolled structure composed of crystal grains 1 ″. The Nd-rich phase 2 precipitates at some grain boundaries in the recrystallized rolled structure. You can see that there is.

As a result of the above X-ray diffraction and observation of the structure by a transmission electron microscope, the anisotropic magnet of the present invention was found to have a tetragonal structure of Nd ₂ Fe
_It can be seen that the ₁₄ B intermetallic compound phase is the main phase, and the Nd ₂ Fe ₁₄ B intermetallic compound phase has a recrystallization rolled structure oriented in the crystallographic C-axis direction.

Examples 6 to 12 and Comparative Examples 6 to 16 Melting and casting were performed using a plasma arc furnace.
An alloy ingot containing _14.0 Fe _79.4 B _6.6 as a main component was manufactured. Put the above alloy ingot in a heat treatment furnace, 1atm Ar
After the gas atmosphere, the alloy ingots were homogenized while maintaining the temperature and time shown in Table 3 to prepare a number of alloy ingots having different homogenization temperatures.

Put these alloy ingots into a heat treatment furnace, vacuum degree: 1.0
× After evacuation to a vacuum of 10 ^-5 Torr, the H ₂ gas so that the H ₂ gas pressure shown in Table 3 to flow into the heat treatment furnace, the H ₂
Temperature from room temperature while maintaining a gas pressure to the holding temperature shown in Table 3 was raised, H ₂ occludes treated and held at that temperature for 6 hours, an additional exhaust while maintaining the H ₂ occlusion treatment temperature 0.5
The treatment was carried out for 10 hours to remove H ₂ until the H ₂ gas pressure shown in Table 3 was reached. Then, Ar gas was introduced into the heat treatment furnace to rapidly cool the furnace.

The alloy ingot quenched after the de-H ₂ treatment is crushed as it is in an Ar gas atmosphere of a heat treatment furnace to form magnet powders, and these magnet powders are each 30 mm in length, 30 mm in width and 30 mm in width.
Height: Filled in a copper can having dimensions of 15 mm. The opening of the can filled with the magnet powder was sealed by electron beam welding in a vacuum to prepare a can-enclosed filling.

The above-mentioned can-enclosed filler was heated to the temperature shown in Table 3 and rolled at the rolling rate shown in Table 3 while maintaining this temperature to produce anisotropic magnets. After heat treatment in an inert gas atmosphere under the conditions shown in Table 3, the magnetic properties of the anisotropic magnet were measured, and the results are shown in Table 3.

In Table 3 above, values marked with * indicate values outside the conditions of the present invention.

From the results shown in Table 3, it can be seen that the R-Fe-B-based anisotropic magnet manufactured under the conditions deviating from even one of the conditions of the present invention does not exhibit sufficient magnetic properties.

Examples 13 to 22 and Comparative Examples 17, 18 Nd-Fe-B alloy ingots having the component compositions shown in Table 4 were produced by melting and casting in a high-frequency melting furnace.

The Nd-Fe-B type alloy ingot of H ₂ gas partial pressure: 150To
rr at a mixture gas atmosphere of H ₂ gas and Ar gas at 840 ° C. for 5 hours to perform an H ₂ occlusion treatment, and then at 850 ° C., a partial pressure of H ₂ gas: 1
H ₂ removal treatment was performed until an Ar gas atmosphere of × 10 ^-2 Torr was reached, followed by rapid cooling. The quenched alloy ingot is heat-treated in an Ar gas atmosphere under the conditions shown in Table 4 and then crushed to a packing density of 80% in a stainless steel can having a diameter of 46 mm and a height of 50 mm. And pressed with a stainless steel lid on the upper part in a vacuum of 5 × 10 ⁻⁴ Torr at a strain rate of 2 × 10 ⁻¹ S ⁻¹ under the conditions shown in Table 4. -An Fe-B type anisotropic magnet was manufactured.

The structure of the obtained anisotropic magnet of the present invention is the above-mentioned Nd ₂ Fe
_The recrystallization rolled structure had a texture in which the ₁₄ B phase was crystallographically oriented in the C-axis direction.

The average crystal grain size of the recrystallized rolled structure was measured, and the magnetic properties of the anisotropic magnet having the recrystallized rolled structure were measured. The results are shown in Table 4. In Table 4, the values marked with * indicate values outside the conditions of the present invention.

Examples 23 to 32 and Comparative Examples 19 and 20 Melted and cast in a high-frequency melting furnace to obtain Nd shown in Table 5.
-An Fe-B based alloy ingot was manufactured.

The ingot was placed in a heat treatment furnace, evacuated to a vacuum of 3 × 10 ⁻⁵ Torr, homogenized at a temperature of 1050 ° C. for 50 hours, and the homogenized alloy ingot was used as the above Examples 13 to 22. and conditions were conducted in Comparative example 17 and 18 exactly H ₂ occluded treated under the same conditions, then quenched after performing de H ₂ treatment. The quenched alloy ingot was heat-treated in an Ar gas atmosphere under the conditions shown in Table 5, then crushed, and packed in a stainless steel can having an inner diameter of 46 mm x height: 50 mm with a packing density of 80%. %, With a stainless steel lid on the top, in a vacuum of 5 × 10 ^-4 Torr and a strain rate of 2 × 10 ^-1 S ^-1 . Was press-compressed under the conditions shown in (1) to produce an R-Fe-B-based anisotropic magnet.

The structure of the obtained anisotropic magnet was a recrystallized rolled structure having a texture in which the Nd ₂ Fe ₁₄ B phase was crystallographically oriented in the C-axis direction.

The average crystal grain size of the recrystallized rolled structure was measured, and the magnetic properties of the anisotropic magnet were measured. The results are shown in Table 5. In Table 5, values marked with * indicate values outside the conditions of the present invention.

From the results of Tables 4 and 5, the average crystal grain size of the recrystallized rolled structure is in the range of 0.05 to 50 μm, preferably 0.1 to 0.5 μm.
It can be seen that when the thickness is in the range of 05 to 10 μm, the magnetic properties are excellent.

Further, in Examples 13 to 22 and Comparative Examples 17 and 18, the Nd-Fe-B-based alloy ingot obtained by melting and casting was used as it is.
H ₂ adsorption process and the de-H ₂ process to contrast is produced with H ₂ treated, Examples 23 to 32 and Comparative Examples 19 and 20, the Nd
-Fe-B-based alloy ingot by H ₂ occlusion processing and de H ₂ treatment were then treated for homogenization only differs in that it produced with H ₂ treated, but the Nd-Fe-B type alloy ingot Comparing the measurement results of the magnetic properties in Table 4 without homogenization treatment with the measurement results of the magnetic properties in Table 5 subjected to homogenization processing, it is understood that the homogenization treatment shows more excellent magnetic properties.

In Examples 1 to 32 and Comparative Examples 1 to 20, Nd
-Fe-B based alloy ingot or homogenized Nd-Fe
The -B alloy ingot to H ₂ occlusion treatment, and quenched After removing H ₂ treatment, without being limited to the above ingot,
Powder obtained by pulverizing an Nd-Fe-B alloy ingot,
Using a Nd-Fe-B-based alloy powder obtained by a conventional Ca reduction diffusion method or the like, or an Nd-Fe-B-based alloy powder obtained by homogenizing the above powder, Examples 1 to 32 and Comparative Examples 1 to An anisotropic magnet can be manufactured in exactly the same manner as in 20.

〔The invention's effect〕

In this invention, the step of manufacturing of H ₂ processed from Nd-Fe-B type alloy ingot or powder may be carried out in a non-oxidizing atmosphere, impurities such as oxygen in H ₂ treating body obtained not be incorporated, also the H ₂ treatment bodies,
When sufficiently performed of H ₂ adsorption process of Nd-Fe-B type alloy ingot, disintegrate into powder, if not disintegrate it may be a magnet powder lightly crushed.

Thus adulteration free H ₂ treating body, anisotropy excellent without being sealed are filled into cans in vacuo and canning packing, which is oxidized be subjected to high-temperature plastic working in air You can get a magnet. For this reason, the manufacturing method of the present invention is simpler than the conventional manufacturing method, has a good yield from the raw material alloy, and can provide an excellent anisotropic magnet, which brings about an industrially excellent effect. is there.

[Brief description of the drawings]

FIG. 1 (a) shows the R- obtained by the production method of the present invention.
FIG. 1 (b) is a schematic view of a structure of a conventional R—Fe—B sintered magnet, and FIG. 1 (c) is a conventional amorphous structure. FIG. 2 (a) is a schematic view of the structure of a permanent magnet obtained by hot-pressing and plastically processing a ribbon. FIG. 2 (a) is a process diagram showing a method for producing an R—Fe—B based anisotropic magnet of the present invention. ) Is a process diagram showing a conventional method for producing an R-Fe-B based sintered magnet, and FIG. 2 (c) is a process diagram showing a conventional permanent magnet produced by hot-pressing and plastically processing an amorphous ribbon. , FIG. 3 is a schematic cross-sectional view of the can-enclosed filling, FIG. 4 is a schematic view showing a state in which the can-enclosed filling is being pressed, and FIG. FIGS. 6 (a) to 6 (e) are schematic diagrams showing a structure change until a recrystallized rolled structure of the present invention is obtained. FIG. 6A is a structure diagram of an alloy ingot obtained by melting and casting, FIG. 6B is a structure diagram of an ingot obtained by homogenizing the cast ingot, and FIG. After transformation, recrystallized R ₂
Fe ₁₄ organization chart B phase has initially occurred, FIG. 6 (d) are the texture of the recrystallized R ₂ Fe ₁₄ B phase, FIG. 6 (e) is obtained by rolling the recrystallization FIG. 7 (a) is a photograph of the metallographic structure of the anisotropic magnet of the present invention taken by a transmission electron microscope, and FIG. 7 (b) is a schematic explanatory view of the photograph of the metallic structure. . 1 ...... R ₂ Fe ₁₄ B phase 1 '... recrystallized R ₂ Fe ₁₄ B phase 1 "...... R ₂ Fe ₁₄ B phase of recrystallized grains rolled grain 2 ...... R-rich phase, 3 ...... B-rich phase 3 mass '...... alpha-Fe phase, a non-equilibrium phase 4 ...... H ₂ treatment of powder 4 such as R ₂ Fe ₁₇ phase' ...... H ₂ treated, 5 ...... press punch 6 Rolling roll 7 Filler in can 8

Continuation of the front page (72) Inventor Ryoji Nakayama 1-297 Kitabukuro-cho, Omiya-shi, Saitama Central Research Laboratory of Mitsubishi Metals Co., Ltd. (72) Inventor Tamotsu O- 1-21-297 Kitabukuro-cho, Omiya City, Saitama Prefecture Central Research Laboratory of Mitsubishi Metals Corporation (56) References JP-A-63-90104 (JP, A) JP-A-60-119701 (JP, A) JP-A-63-111155 (JP, A) JP-A-63-38216 (JP, A) JP-A-62-23902 (JP, A) JP-A-63-178505 (JP, A) JP-A-63-121601 (JP, A) JP-A-63-116404 (JP, A) JP-A-60-100402 (JP, A) JP, A) JP-A-63-213320 (JP, A) JP-A-63-226007 (JP, A)

Claims (7)

(57) [Claims] 1. A rare earth element containing Y (hereinafter referred to as R)
An ingot or powder of an alloy containing Fe and B as a main component is kept in an H ₂ gas atmosphere or a mixed atmosphere of H ₂ gas and an inert gas at a temperature of 500 to 1000 ° C., Alternatively, the powder is allowed to absorb H ₂ , and the H ₂ gas pressure is 1 × 10 ⁻¹ Torr or less, or the H ₂ gas partial pressure is 1 × 10 ⁻¹ Torr or less until the temperature becomes an inert gas atmosphere. H ₂ treated at 1000 ° C., cooled to form an H ₂ treated body, and the H ₂ treated body is plastically worked at a temperature of 600 to 900 ° C. to form a bulk material, a rare earth-Fe—B system Manufacturing method of anisotropic permanent magnet. 2. After the above-mentioned H ₂ removal treatment, the temperature is 300 to 1000 ° C.
In heat-treated and cooled with H ₂ treated, the H ₂ treatment body temperature: 600 to 900 ° C., characterized in that the plastic working to the bulk material in claim 1, wherein the rare earth -Fe-
A method for producing a B-based anisotropic permanent magnet. 3. An ingot or powder of an alloy mainly composed of R, Fe and B is kept at a temperature of 600 to 1200 ° C., and after the ingot or the powder is homogenized, H ₂ gas is added. in a mixed atmosphere of atmosphere or H ₂ gas and an inert gas, temperature in the 500 to 1000 ° C. and held into ingots were homogenized in the alloy or homogenized powder was allowed to absorb H _2, H ₂ gas pressure: 1 × 10 ^-1 Torr or less in a vacuum atmosphere or H ₂ gas partial pressure: 1 × 10 ^-1 Torr or less in temperature until the inert gas atmosphere: de H ₂ treatment at 500 to 1000 ° C., then cooled and with H ₂ treated Te, the temperature of the above H ₂ processed: 600-900 the preparation of rare earth -Fe-B based anisotropic permanent magnet, characterized in that the bulk material to plastic working at ° C.. 4. After the above-mentioned H ₂ removal treatment, the temperature is 300 to 1000 ° C.
In heat-treated and cooled with H ₂ treated, the H ₂ treatment body temperature: 600 to 900 by plastic working at ℃ characterized by a bulk material according to claim 3, wherein the rare earth -Fe-
A method for producing a B-based anisotropic permanent magnet. 5. The composition of the alloy containing R, Fe, and B as a main component is 11.8 ≦ X ≦ 15 in R _x (Fe, B) _100-X in atomic percentage.
5. The method for producing a rare earth-Fe—B based anisotropic permanent magnet according to claim 3, wherein a homogenized ingot of an alloy containing R, Fe, and B as a main component is used. . 6. The H ₂ gas pressure or the H ₂ gas partial pressure in the H ₂ gas atmosphere or in a mixed atmosphere of H ₂ gas and an inert gas.
The rare earth-Fe according to claim 1, 2, 3, 4, or 5, wherein the pressure is 10 to 760 Torr.
-A method for producing a B-based anisotropic permanent magnet. 7. The rare earth-Fe-B system according to claim 1, wherein the plastically processed bulk material is further heat-treated at a temperature of 300 to 1000 ° C. Manufacturing method of anisotropic permanent magnet.