JPH0745412A - R-fe-b permanent magnet material - Google Patents

Abstract

PURPOSE:To enable effective fine grinding and to acquire good oxidation resistance by containing R2Fe14B and specifying average grain diameter, apparent density, orientation degree and magnetic characteristic. CONSTITUTION:A casting piece of fine and uniform structure is manufactured, which is comprised of R (R is at least one kind of rare earth elements including Y) of 12 to 16 atomic %, B of 4 to 8 atomic %, O3 of 5000ppm or less and a remaining part of Fe (Fe is partially displaced with one or two kinds of Ni) and inevitable impurities and contains a main phase of R2Fe14B of 90% or more. After the casting piece is hydrogen occluded, fine powder 7 which is obtained by finely grinding alloy powder stabilized by de-H2 treatment is orientated by a pulse coil 6 to realize average grain diameter of 10mum or less, apparent density of 7.45g/cm<3> or more and orientation degree of 85% or more. Thereafter, it is molded and sintered to acquire a total of (BH)max value and iHc value of 59 or more and angularity {(Br<2>/4)/(BH)max} of 1.01 to 1.045.

Description

Detailed Description of the Invention

[0001]

The present invention relates to R (provided that R contains at least one rare earth element including Y), Fe,
Regarding the R-Fe-B based permanent magnet material containing B as a main component,
A molten alloy containing R, Fe, and B as main components is obtained by a strip casting method such as a single roll method or a twin roll method to obtain a slab having a homogeneous structure in which an R-rich phase having a specific plate thickness is finely separated. The H ₂ occlusion property of the R-containing Fe alloy is used to spontaneously disintegrate the slab and further de-H ₂ treatment for stabilization, enabling efficient pulverization, and further after orienting the fine powder in a pulsed magnetic field. Manufactured by molding, sintering, aging treatment,
Characteristic values of A and coercive force iHc (kOe);; maximum energy product value (BH) max (MGOe) have a total value A + B of 59 or more values B, squareness ^{{(Br 2/4) /} ( B
H) max} relates to a high performance R-Fe-B based permanent magnet showing a value of 1.01 to 1.045.

[0002]

2. Description of the Related Art Today, R is a typical high-performance permanent magnet.
-Fe-B system permanent magnet (JP-A-59-46008)
Has high magnet characteristics due to the structure of the ternary tetragonal compound having the main phase and the R-rich phase, and is used in a wide range of fields from various household electrical appliances to large computer peripherals, depending on the application. R-Fe-B based permanent magnets of various compositions have been proposed so as to exhibit various magnet characteristics. However, there are strong demands for smaller and lighter electric and electronic devices as well as higher functionality, and further higher performance and cost reduction of R—Fe—B permanent magnets are required.

Generally, the residual magnetic flux density (Br) of an R-Fe-B system sintered magnet can be expressed by the following equation (1). Br ∝ (Is · β) · f · {ρ / ρ ₀ · (1-α)} ^2/3 Equation (1) where Is: Saturation magnetization β: Temperature dependence of saturation magnetization f: Orientation degree ρ: Burning Consistency density ρ ₀ : Theoretical density α: Grain boundary phase (volume ratio of non-magnetic phase) Therefore, the residual magnetic flux density (B
In order to increase r), 1) the ferromagnetic phase and R of the main phase
_{2 To} increase the abundance of the Fe ₁₄ B phase, 2) to increase the density of the sintered body to the theoretical density of the main phase, and 3) to further increase the degree of orientation of the main phase crystal grains in the easy axis direction of magnetization. Required.

That is, in order to achieve the above item 1),
It is important to bring the composition of the magnet close to the stoichiometric composition of the above R ₂ Fe ₁₄ B, but the alloy ingot having the above composition melted and cast in a mold is used as a starting material in the R—Fe—B system. When trying to make a sintered magnet, α-
Since Fe and R-rich phases are locally ubiquitous, there is a problem that it becomes difficult to pulverize particularly during fine pulverization and compositional deviation occurs. More specifically, when the alloy ingot is occluded with H ₂ and dehydrogenated with H ₂ to perform mechanical pulverization (JP-A-60-63304, JP-A-63-33505),
The α-Fe crystallized in the alloy lump remains as it is during grinding,
Owing to its spreading property, it hinders crushing, and the locally ubiquitous R-rich phase produces hydrides by H ₂ storage treatment and becomes a fine powder, so that oxidation during mechanical crushing occurs. Acceleration, and in the pulverization using a jet mill, compositional deviation occurs due to scattering in a dominant manner.

Further, in order to achieve the above item 1), R ₂ Fe ₁₄
When an attempt is made to produce a sintered body by using an alloy powder having a stoichiometric composition of B, the Nd-rich phase for causing liquid phase sintering is an oxide due to inevitable oxidation in the production process of the sintered body. Since it is consumed and cannot be sintered or the amount of the R ₂ Fe ₁₄ B phase is increased, the amount of the Nd-rich phase or the B-rich phase is inevitably decreased. Was made even more difficult. Furthermore, it is one of the indexes showing the stability of the permanent magnet material,
In addition, the coercive force (iHc), which is one of the important properties, is reduced. Further, regarding the above item 3), in the method for producing an R-Fe-B based permanent magnet,
In order to align the easy-axis directions of the main phase crystal grains, a method of press molding in a magnetic field is adopted. At that time, by the direction of pressure application direction and press-magnetic field, the residual magnetic flux density (Br) value and the squareness ^{{(Br 2/4) /} (BH)
It is known that the value of max} changes and is also affected by the strength of the applied magnetic field.

[0006]

Recently, coarsening of crystal grains, which is a defect of the R-Fe-B alloy powder by the ingot crushing method,
In order to prevent α-Fe from remaining and segregating, R-Fe-B
The molten alloy is made into a slab of a specific plate by the twin roll method,
The slab is roughly pulverized by a standard powder metallurgical method by a slump pump, jaw crusher or the like, and then mechanically pulverized by a disc mill, a ball mill, an attritor, a jet mill or the like to obtain a powder having an average particle diameter of 3 to 5 μm. In Japanese Patent Application Laid-Open No. 63-317643, there is proposed a manufacturing method in which after pulverization, pressing in a magnetic field and sintering aging treatment are performed.
However, in the above method, compared with the case of the ingot crushing method of casting in a conventional mold, it is not possible to expect a dramatic improvement in the pulverization efficiency during fine pulverization, and during fine pulverization, not only grain boundary pulverization but also intragranular Since crushing also occurs, it is not possible to achieve a significant improvement in magnetic properties, and because the R-rich phase is not a stable RH ₂ phase against oxidation, and because the R-rich phase is fine and has a large surface area, It is inferior in oxidation resistance, oxidation progresses during the process, and high characteristics cannot be obtained. Recently, there is a strong demand for cost reduction of R-Fe-B based permanent magnet materials, and it has become extremely important to efficiently produce high-performance permanent magnets. Therefore, it is necessary to improve the manufacturing conditions to bring out the characteristics that are close to the limit.

The present invention solves the above-mentioned problems in the method for producing an R-Fe-B system permanent magnet material, enables efficient fine pulverization, is excellent in oxidation resistance, and has fine crystal grains of the magnet. By increasing the degree of iHc, and further increasing the degree of orientation of each crystal grain in the easy magnetization direction, (BH) max
Value (MGOe); and A, iHc value (kOe); the sum of B, has a value of A + B ≧ 59, squareness {(Br ^2/4)
The objective is to provide a high-performance R-Fe-B based permanent magnet material exhibiting a value of / (BH) max} of 1.01 to 1.045.

[0008]

The inventors of the present invention firstly investigated the R-F.
As a result of various studies on the pulverization method using the e-B alloy as the starting material, the fine pulverization efficiency was improved, the oxidation resistance was excellent, and the magnetic properties of the magnet alloy, particularly iHc, were studied. the R-Fe-B cast piece produced by the strip casting method, after hydrogen occlusion, de H ₂
When the treated and stabilized alloy powder is finely pulverized, the fine pulverizing ability is improved about twice as much as the conventional one, and the fine powder is oriented by applying a pulse magnetic field, and then shaped and sintered. by, (BH) sum of max value and iHc value has 59 or more values, squareness ^{{(Br 2/4) /} (BH) max}
Shows a value of 1.01 to 1.045 and the iH of the sintered magnet is
It was found that c was improved. That is, H ₂ is added to an R-Fe-B based alloy having a specific composition having a structure in which an R-rich phase having a specific thickness that has been strip cast is finely separated.
When occluded, the finely dispersed R-rich phase forms a hydride and volume-expands, so that the alloy can spontaneously disintegrate, and as a result, finely pulverized crystals forming an alloy lump. It becomes possible to subdivide the grains,
A powder having a uniform particle size distribution can be produced.

In this case, it is particularly important that the R-rich phase is finely dispersed and the R ₂ Fe ₁₄ B phase is fine. Moreover, in the method of smelting an alloy ingot by using an ordinary mold, when the alloy composition is brought close to the stoichiometric composition of R ₂ Fe ₁₄ B, crystallization of Fe primary crystal is difficult to avoid and fine pulverization in the next step is performed. It becomes a factor that greatly reduces the performance. Therefore, heat treatment is applied for the purpose of homogenizing the alloy ingot, and a means for eliminating α-Fe is taken, but with the coarsening of the main phase crystal grains,
Since segregation of the R-rich phase also progresses, it is difficult to improve the iHc of the sintered magnet. In addition, it is also possible to align the easy magnetization axis directions of the main phase crystal grains, that is, to increase the degree of orientation with high Br
It is an indispensable condition for attaining the improvement of the flatness and the squareness, and therefore the method of pressing the powder in the magnetic field is adopted.

However, the coil and the power source arranged in a usual press device (hydraulic press, mechanical press) for generating a magnetic field have a maximum of 10 kOe to 20 k.
Only the magnetic field of Oe can be generated, and the squareness {(B
^{r 2/4) / (BH} ) max} also becomes 1.05 or more values, theoretical expected from Br value (BH) m
ax value (in this case, the squareness of ^{{(Br 2/4) /} (B
It was difficult to reach H) max} of 1.00). Therefore, we tried molding in a higher magnetic field, but in order to generate a higher magnetic field, it is necessary to increase the number of turns of the coil, and it is also necessary to increase the size of the device that requires a high power supply. To do. The present inventors analyzed the relationship between the magnetic field strength during pressing and Br of the sintered body. The higher the magnetic field strength, the higher the Br value, the higher the squareness, and the momentarily strong. It has been found that by using a pulsed magnetic field capable of generating a magnetic field, higher Br and higher squareness can be achieved. Furthermore, in the method using a pulsed magnetic field, it is important to momentarily orientate once with the pulsed magnetic field, and it is possible to shape the powder by a hydrostatic press, and the combination of the pulsed magnetic field and the static magnetic field by an electromagnet can be combined. It was found that it is also possible to perform press molding in a magnetic field.

According to the present invention, R (provided that R is at least one of rare earth elements including Y) is 12 atom% to 16 atom%,
B4 atomic% to 8 atomic%, O ₂ 5000 ppm or less, balance Fe (however, a part of Fe can be replaced by one or two kinds of Co and Ni) and unavoidable impurities, and R ₂ Fe _{14 of the} main phase 90% or more of B, having an average particle size of 10 μm or less and an apparent density of 7.45 g / cm ³ or more,
Orientation degree is 85% or more, (BH) max value; A (M
GOe) and iHc value; sum of B (kOe) A + B is 5
Have 9 or more, squareness ^{{(Br 2/4) /} (BH)
max} has a value of 1.01 to 1.045, which is an R-Fe-B based permanent magnet material.

The magnetic characteristics of the R-Fe-B system permanent magnet of the present invention are as follows: maximum energy product (BH) max value; A (MG
Oe) and coercive force iHc value (kOe);
When B has 59 or more and BH (max) is 50 MGOe or more, iHc is 9 kOe or more, and BH (m
iHc is 14 kO when ax) is 45 MGOe or more.
above e, squareness ^{{(Br 2/4) /} (BH) max}
The required magnetic characteristics can be obtained by appropriately selecting the values of 1.01 to 1.045, the composition, the manufacturing conditions, and the like.

In the present invention, the cast slab of the magnetic material having the structure in which the R-rich phase of the specific composition is finely separated is manufactured by the alloy casting of the specific composition by the single-roll method or the strip-casting method by the twin-roll method. It The obtained slab is a thin plate material having a plate thickness of 0.03 mm to 10 mm, and the single roll method and the twin roll method are used properly depending on the desired slab plate thickness, but when the plate thickness is thick, the twin roll method is used. Further, when the plate thickness is thin, it is preferable to adopt the single roll method.
The reason for limiting the plate thickness of the cast slab to 0.03 mm to 10 mm is that if it is less than 0.03 mm, the quenching effect becomes large, the crystal grain size becomes smaller than 1 μm, and it easily oxidizes when pulverized. Is not preferable, and if it exceeds 10 mm, the cooling rate becomes slow, and α
This is because —Fe is likely to crystallize, the crystal grain size becomes large, and the Nd-rich phase is unevenly distributed, which deteriorates the magnetic properties, which is not preferable.

In the present invention, the cross-sectional structure of the R-Fe-B type alloy having a specific composition obtained by the strip casting method is an ingot obtained by casting the main phase R ₂ Fe ₁₄ B crystal in a conventional mold. The size is about 1/10 or more finer than that of, for example, the dimension in the minor axis direction is 0.1 μm to
It is a fine crystal of 50 μm and 5 μm to 200 μm in the long axis direction, and the R-rich phase is finely dispersed so as to surround the main phase crystal grains, and the size thereof is even in a region ubiquitous in a local area. Is 20 μm or less. By finely separating the R-rich phase to 5 μm or less, volume expansion when the R-rich phase forms a hydride during the H ₂ occlusion treatment is uniformly generated and fragmented. The crystal grains are subdivided to obtain a fine powder having a uniform particle size distribution.

H₂For the occlusion process, for example,
A broken piece of 0.03 mm to 10 mm thick slab is used as the raw material case.
A container that can be inserted into the container and the raw material case can be closed by closing the lid.
After charging the inside of the container and sealing it, after evacuating the inside of the container, 2
00 Torr-50kg / cm²H of pressure₂Gas supply
And add H to the slab.₂To store. This H₂The occlusion reaction is
Since it is an exothermic reaction, cooling water is supplied to the outer circumference of the container.
Cooling pipes are installed around the container to prevent temperature rise in the container
H of pressure₂By supplying gas for a certain period of time, H₂gas
Are absorbed and the slab naturally disintegrates and is pulverized. further,
After cooling the powdered alloy, de-H removal in vacuum₂Gas treatment
To do. The alloy powder of the above treatment has fine cracks in the grains.
Therefore, it is finely pulverized in a short time with a pole mill, jet mill, etc.
To obtain alloy powder having a required particle size of 1 μm to 80 μm.
You can H₂Gas pressure is 2kg / cm for mass production²
-10kg / cm²Is preferred. In this invention, H₂
The processing time for pulverization by occlusion is the size of the closed container,
Size of fracture mass, H₂5 minutes depending on gas pressure
The above is necessary.

After cooling the alloy powder pulverized by the H ₂ occlusion, the primary H ₂ degassing treatment is performed in a vacuum. Further, the powdered alloy is heated to 100 ° C. in vacuum or argon gas.
Was heated to to 750 ° C., preventing the two Tsugida' H ₂ gas treatment over 0.5 hours, with H ₂ gas in the pulverized alloy can be completely removed, the oxidation of the powder or pressed bodies due to long-term storage As a result, it is possible to prevent deterioration of the magnetic properties of the obtained permanent magnet. The heating temperature in the above dehydrogenation treatment is 1
If the temperature is lower than 00 ° C, it takes a long time to remove H ₂ remaining in the disintegrated alloy powder, which is not mass-productive. Further, at a temperature of higher than 750 ° C., a liquid phase appears and the powder is solidified, which makes fine pulverization difficult and deteriorates the formability at the time of pressing. Therefore, it is preferable in the case of producing a sintered magnet. Absent.
Further, considering the sinterability of the sintered magnet, the preferable dehydrogenation treatment temperature is 200 ° C to 600 ° C. Further, the treatment time varies depending on the treatment amount, but 0.5 hours or more is required.

Next, for fine pulverization, an inert gas (for example, N 2
_2. Fine pulverize with a jet mill using Ar). Of course, it is also possible to use a ball mill using an organic solvent (for example, benzene, toluene, etc.) or attritor grinding. The average particle size of the finely pulverized powder is 1 μm to 10 μm.
m is preferred.

For pressing using a magnetic field, the following method is proposed. The finely pulverized powder is filled in a mold in an inert gas atmosphere. The mold may be made of non-magnetic metal or oxide, or may be an organic compound such as plastic or rubber. The packing density of the powder is preferably in the range of the bulk density of the powder in a static state (packing density 1.4 g / cm ³ ) to the solidified bulk density after tapping (packing density 3.0 g / cm ³ ). Therefore, the packing density is 1.4 to 3.0 g / cm ^3.
Limited to The powder is oriented by applying a pulsed magnetic field from an air-core coil or a condenser power supply. During orientation,
A pulse magnetic field may be repeatedly applied while performing compression using the upper and lower punches. The higher the strength of the pulsed magnetic field, the better, and at least 10 kOe or more is required. As for the waveform of the pulse magnetic field in the present invention, as shown in FIG. 2, the time (Time) of one waveform of the pulse magnetic field is preferably 5 μsec to 100 msec, and the number of pulse magnetic fields applied is 1 to 10 times, preferably 1 time. ~ 5 times. The powder after orientation can be hardened by isostatic pressing.
At this time, when a plastic mold is used, the isostatic pressing can be performed as it is. Also,
In order to continuously perform orientation and pressing with a pulsed magnetic field, it is possible to embed a coil that generates a pulsed magnetic field inside the die, orient using the pulsed magnetic field, and then perform molding using a normal magnetic field pressing method. Is.

The reasons for limiting the composition of the ingot for rare earth / boron / iron-based permanent magnet alloy in the present invention will be described below. The rare earth element R contained in the ingot for permanent magnet alloy of the present invention is a rare earth element including yttrium (Y) and including light rare earth and heavy rare earth. As R, a light rare earth element is sufficient, and Nd and Pr are particularly preferable. Usually, one kind of R is sufficient, but in practice, a mixture of two or more kinds (Missille metal, didymium, etc.) can be used for the reason of convenience of acquisition, and Sm, Y, La, Ce,
Gd and the like can be used as a mixture with other R, especially Nd and Pr. It should be noted that this R does not have to be a pure rare earth element, and may contain impurities that are unavoidable in production within the industrially available range. R is R-Fe-
Is an essential element of the alloy ingot for producing the B-based permanent magnet,
If it is less than 12 atom%, high magnetic properties, particularly high coercive force, cannot be obtained, and if it exceeds 16 atom%, the residual magnetic flux density (Br) is lowered and a permanent magnet having excellent characteristics cannot be obtained. Therefore,
R is in the range of 12 atom% to 16 atom%, but the optimum R
The range is 12.5 atomic% to 14 atomic%.

B is an essential element of the alloy ingot for producing the R-Fe-B system permanent magnet. If it is less than 4 atom%, a high coercive force (iHc) cannot be obtained, and if it exceeds 8% atom, it remains. Since the magnetic flux density (Br) decreases, an excellent permanent magnet cannot be obtained. Therefore, B is 4 atom% to 8 atom%,
The optimum range of B is 5.8 atom% to 7 atom%.

When Fe is less than 76 atomic%, the residual magnetic flux density (Br) is lowered, and when it exceeds 84 atomic%, a high coercive force cannot be obtained. Therefore, Fe is limited to 76 to 84 atomic%.
The reason for substituting a part of Fe with one or two of Co and Ni is that the effect of improving the temperature characteristics of the permanent magnet and the effect of improving corrosion resistance can be obtained.
When one or two kinds of Ni exceeds 50% of Fe, a high coercive force cannot be obtained, and an excellent permanent magnet cannot be obtained. Therefore, the upper limit of Co and Ni is 50% of Fe.

The reason why O ₂ is limited to 5000 ppm or less is that when it exceeds 5000 ppm, the R-rich phase is oxidized and a sufficient liquid phase cannot be generated during sintering, and the density is lowered, so that a high magnetic flux density is obtained. Is not preferable and the weather resistance is deteriorated, so that the optimum range of O ₂ is 200 to
It is 3000 ppm. Further, when the apparent density of the permanent magnet material is less than 7.45 g / cm ² , a high magnetic flux density cannot be obtained, and the (BH) max value, which is a feature of the present invention; A (MGO
e) and iHc value; B (kOe) total value A + B is not preferable because a magnetic material having 59 or more cannot be obtained.

Further, as the starting raw material powder in the present invention, in addition to the raw material powder of the magnet composition, in order to adjust the R content, the B content and the Fe content to the magnet composition, for example, the R content is 16 atomic% or more. ₂ Fe ₁₄ to R-Fe-B alloy powder and R amount B phase as the main phase is used by blending mixing the R-Fe-B alloy powder containing 12 atomic% or less of R ₂ Fe ₁₇ phase Is also possible. Regarding the B content, the main phase R-Fe-B alloy powder containing 8 atomic% or more of the B content and the B content of 4
R-Fe-B based alloy powder for adjustment containing R ₂ Fe ₁₇ phase of atomic% or less, or R-Fe based alloy powder for adjustment containing R ₂ Fe ₁₇ phase not containing B is mixed and mixed to obtain a magnet composition. Can also be adjusted. Furthermore, R-Co intermetallic compound _{(Nd 3 -Co, Nd-Co} 2 and the like) for adjusting R-Co containing
The magnet composition can be adjusted by mixing and mixing alloy powder (which can be replaced by Fe).

The alloy ingot according to the present invention has R,
In addition to B and Fe, the presence of impurities that are unavoidable in industrial production can be tolerated, but a part of B is 4.0 atomic% or less of C and 3.5.
P of atomic% or less, S of 2.5 atomic% or less, 3.5 atomic%
Improving the manufacturability of a magnet alloy by substituting at least one of the following Cu with a total amount of 4.0 atomic% or less
The price can be reduced. Further, in the R, B, Fe alloy or the R-Fe-B alloy containing Co, 9.5 atomic% or less of Al, 4.5 atomic% or less of Ti, 9.5 atomic% or less of V, 8 0.5 atomic% or less Cr, 8.0 atomic% or less Mn, 5 atomic% or less Bi, 12.5 atomic% or less Nb, 10.5 atomic% or less Ta, and 9.5 atomic% or less Mo. , W of 9.5 atomic% or less, S of 2.5 atomic% or less
b, Ge of 7 atomic% or less, Sn of 35 atomic% or less, 5.
By adding at least one of Zr of 5 atomic% or less and Hf of 5.5 atomic% or less, a high coercive force of the permanent magnet alloy becomes possible.

In the R—B—Fe system permanent magnet of the present invention, it is essential that 90% or more of the main phase of the crystal phase, R ₂ Fe ₁₄ B phase, is present. Currently mass-produced R-F
In the eB sintered magnet, the R ₂ Fe ₁₄ B phase is 90% at maximum.
If it is less than 90%, the high magnetic property of A + B value of 59 or more of the present invention cannot be obtained. The orientation degree of the magnet of the present invention is calculated from the above equation 1), and the orientation degree of the magnet is 85.
% Is essential for maintaining the A + B value of 59 or more, and if the degree of orientation is less than 85, the squareness of the demagnetization curve decreases, and the high residual magnetic flux density (Br) decreases. The BH) max value decreases, which is not preferable. The preferred degree of orientation is 92% or more. In addition, squareness {(B
If ^{r 2/4) / (BH} ) max} is theoretical 1.00
However, in the actual permanent magnet material, since the above-mentioned disorder of the orientation degree is inevitably generated,
Even if various improvements were carried out, the limit was that it reached 1.05, but the permanent magnet material of the present invention obtained by the above-mentioned specific manufacturing method has a squareness value of 1.01. ~ 1.0
It becomes 45.

[0026]

According to the present invention, H ₂ is added to an R-Fe-B type alloy having a specific composition with a specific plate thickness which has been strip cast.
By the occlusion, the finely dispersed R-rich phase produces a hydride and volume-expands to spontaneously collapse the alloy, and then finely pulverizes the crystal grains of the main phase constituting the alloy lump to subdivide them. It is possible to produce a powder having a uniform particle size distribution, in which case the R-rich phase is finely dispersed, and the R ₂ Fe ₁₄ B phase is also finely divided, and stable after de-H ₂ treatment. When finely pulverized alloyed alloy powder is finely pulverized, the fine pulverization ability is about twice as high as that of the conventional one. Therefore, the production efficiency is significantly improved, and by aligning and pressing with a pulse magnetic field, Br, It is possible to obtain an R-Fe-B based permanent magnet having a value of 1.01 to 1.04 in which BH (max) and iHc are remarkably improved and improved, and the squareness is as close as possible to the theoretical state.

[0027]

【Example】

Example 1 Nd13.0-B obtained by melting in a high frequency melting furnace
Using a twin roll type strip caster provided with two copper rolls having a diameter of 200 mm, an alloy melt having a composition of 6.0-Fe81 was used to obtain a thin plate-shaped slab having a plate thickness of about 1 mm. The crystal grain size in the slab is 0.5 μm to 15 μm in the minor axis direction,
The dimension in the major axis direction is 5 μm to 80 μm, and the R-rich phase is present in a finely separated state of about 3 μm so as to surround the main phase. Further, the contained O ₂ amount was 300 ppm. After breaking the slab to 50 mm square or less, the broken piece 1000 g
Is housed in a closed container capable of sucking and exhausting N _{2, and}
The gas was allowed to flow for 30 minutes to replace the air, and then 3 kg / cm ² of H ₂ gas was supplied into the container for 2 hours to spontaneously collapse the slab by the H ₂ sucker, and then 500 in vacuum. The mixture was kept at ℃ for 5 hours to remove H ₂ and then cooled to room temperature and further pulverized to 100 mesh. Next, 800 g of the coarsely pulverized sample was pulverized with a jet mill to obtain an alloy powder having an average particle size of 3.5 μm. Using the obtained alloy powder, a raw material powder was filled in a rubber mold, and a pulsed magnetic field of 60 kOe was momentarily applied and oriented, and then a pressure of 2.5 T / cm ² was applied by a hydrostatic press machine. It was hydrostatically pressed. The molded body taken out of the mold was sintered at 1090 ° C. for 3 hours and was aged at 600 ° C. for 1 hour to obtain a permanent magnet. Table 1 shows the magnetic properties and density, the crystal grain size, the degree of orientation, the squareness, the amount of main phase, and the amount of O ₂ contained in the obtained permanent magnet.

Example 2 A molten alloy having the same composition as in Example 1 was strip cast to obtain a thin plate-shaped cast piece having a plate thickness of about 0.5 μm. The crystal grain size in the cast piece is 0.3 μm to 12 μm in the minor axis direction,
The major axis direction was 5 μm to 70 μm, and the R-rich phase was finely separated to about 3 μm so as to surround the main phase. The slab was subjected to jet mill pulverization under the same conditions as in Example 1 to obtain an alloy powder having an average particle size of about 3.4 μm.
As shown in FIG. 1, the static magnetic field coils 3 and 4 are arranged on the outer peripheral portions of the upper and lower punches 1 and 2, and the pulse magnetic field coil 6 is arranged in the die 5 so that the raw material powder 7 is supplied with the pulse magnetic field. Using a pressing device that can be used in combination with and a normal static magnetic field, first, orientation was performed with a pulse magnetic field of about 30 kOe, and then press molding was performed in a magnetic field of about 12 kOe.
Thereafter, the molded body was sintered and aged under the same conditions as in Example 1. The magnet characteristics and density of the obtained permanent magnet,
Table 1 shows the crystal grain size, orientation degree, squareness, main phase amount, O ₂ content, and density.

Example 3 As in Example 1, Nd13.5-Dy0.5-B6.5
An alloy of -Co1.0-Fe78.5 was strip-cast to obtain a thin plate-shaped cast piece. After breaking this to 50 mm square or less, 1000 g was spontaneously disintegrated by H ₂ occlusion in the same manner as in Example 1 and then subjected to H ₂ removal treatment in vacuum for 6 hours. This was roughly pulverized and then jet mill pulverized to obtain a powder having an average particle size of 3.5 μm. The obtained powder was subjected to pulse magnetic field orientation and hydrostatic pressing in the same manner as in Example 1 to prepare a molded body, and similarly sintered and heat treated. Magnetic properties and density of the obtained permanent magnet, crystal grain size, orientation degree, squareness, main phase amount,
The amount of O ₂ contained is shown in Table 1.

Comparative Example 1 Powder obtained under the same conditions as in Example 1 was press-molded in a dry state in a magnetic field of about 12 kOe in a normal magnetic field press machine, and then under the same conditions as in Example 1. , Sintering, and aging treatment. However, it was impossible to densify to a sufficient sintered density due to oxidation during the process such as pressing, and it was impossible to measure the magnet characteristics. Therefore, it was only necessary to measure the density and the O ₂ content. It was

Comparative Example 2 The coarsely pulverized powder obtained under the same conditions as in Example 1 was ball-milled using toluene as a solvent to prepare a fine powder having an average particle size of 3.5 μm. Press molding in a magnetic field of about 12 kOe with
Then, sintering and aging treatment were performed under the same conditions as in Example 1. Magnetic properties and density of the obtained permanent magnet, crystal grain size,
Table 1 shows the orientation degree, the squareness, the amount of main phase, and the amount of O ₂ contained.

Comparative Example 3 Nd14-B6.0 obtained by melting in a high frequency melting furnace
A molten alloy of —Fe80 composition was cast in an iron mold. As a result of observing the structure of the obtained alloy ingot, crystallization of primary crystal Fe was recognized, so that heat treatment was performed at 1050 ° C. for 10 hours to perform homogenization treatment. The crystal grain size of the ingot is 30 to 1 in the minor axis direction.
The thickness was 50 μm and 100 to several mm in the major axis direction, and the R-rich phase was locally segregated with a size of about 150 μm. After this alloy ingot was crushed, H ₂ occlusion treatment and H ₂ removal treatment were carried out in the same manner as in Example 1 to obtain a coarse powder. Furthermore, Example 1
Jet mill crushed under the same conditions as above, average particle size of about 3.7
The powder obtained from the alloy of μm was press-molded in a magnetic field of about 12 kOe, and sintered and heat-treated under the same conditions as in Example 1. Table 1 shows the properties and density of the obtained permanent magnet, the crystal grain size, the degree of orientation, the squareness, the amount of main phase, and the amount of O ₂ contained.

Comparative Example 4 A strip casting slab having the same composition and the same plate thickness as in Example 1 was roughly crushed to 50 mm or less, and then 1000 g of the roughly crushed powder was stamp-milled without H ₂ occlusion treatment and de-H ₂ treatment. After crushing for 1 hour to make 100 mesh coarse crushed powder, crushed by jet mill, average particle diameter of about 3.8μ
m alloy powder was obtained. The alloy powder was pressed in a magnetic field in a magnetic field of about 12 kOe, sintered, and aged to obtain a permanent magnet. Table 1 shows the magnetic properties and density, crystal grain size, orientation degree, squareness, main phase content, O ₂ content, and density of the obtained permanent magnet.
Represent.

Comparative Example 5 Nd13.5-Dy0.5-B6.5-Co1.0-F
An alloy having a composition of e78.5 was cast by the same method as in Comparative Example 3. Since primary Fe crystals had crystallized in the obtained alloy ingot, heat treatment was performed at 1050 ° C. × 6 Hr. After this alloy ingot coarsely pulverized similarly H ₂ occlusion treatment as in Example 1, it was subjected to de-H ₂ treatment in vacuum. This was roughly crushed and then crushed with a jet mill to obtain a powder having an average particle size of about 3.7 μm. Furthermore, after pressing in a magnetic field in a magnetic field of about 12 kOe, sintering and heat treatment were performed under the same conditions as in Example 1. Table 1 shows the magnetic properties and density, crystal grain size, orientation degree, squareness, main phase amount, and O ₂ content of the obtained permanent magnet.

Comparative Example 6 An alloy having the composition of Nd16.5-B7-Fe76.5 was cast in the same manner as in Comparative Example 3 after casting an ingot, and without subjecting to solution treatment.
After roughly crushing the ingot, coarse crushing was performed by a stamp mill in the same manner as in Comparative Example 4, and then fine powder having an average particle size of about 3.7 μm was obtained by a jet mill. Further, after pressing in a magnetic field in a magnetic field of about 12 kOe, sintering and aging treatment were performed under the same conditions as in Example 1 to obtain the magnet characteristics and density, crystal grain size, orientation degree and angle of the obtained permanent magnet. Table 1 shows the moldability, the amount of main phase, and the amount of O ₂ contained.

[0036]

[Table 1]

[0037]

According to the manufacturing method of the present invention, an R-Fe-B alloy melt having a specific composition is formed into a slab having a specific plate thickness by strip casting, and the slab is allowed to occlude H ₂ and spontaneously disintegrate. by, then, it becomes possible to subdivide the crystal grains of the main phase constituting an alloy ingot alloy powder was stabilized by removing H ₂ treated with finely ground, particle size distribution uniform powder , The R-rich phase and the R ₂ Fe ₁₄ B phase are also miniaturized at the time of pulverization, and can be made to be resistant to oxidation when magnetized by pressing after orientation using a pulsed magnetic field. Magnetic properties of magnet alloys, especially maximum energy product value (BH) max (MG
Oe); characteristic value of A and coercive force iHc (kOe); total value of A + B has a value of 59 or more, and squareness {(Br ² /
4) / (BH) max} is 1.01 to 1.045, and a high performance R-Fe-B system permanent magnet is obtained.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a press device that can act by using a pulse magnetic field and a normal static magnetic field together.

FIG. 2 is a graph showing a relationship between time of a pulsed magnetic field and magnetic field strength.

[Explanation of symbols]

 1, 2 Punch 3, 4 Static magnetic field coil 5 Die 6 Pulse magnetic field coil 7 Raw material powder

Claims (1)

[Claims] 1. R (where R is at least one of rare earth elements including Y) 12 atom% to 16 atom%, B4 atom%
.About.8 atomic%, O ₂ 5000 ppm or less, balance Fe (however, a part of Fe can be replaced by one or two kinds of Co and Ni) and inevitable impurities, and R ₂ Fe _{14 of the} main phase
90% or more of B, an average particle size of 10 μm or less, an apparent density of 7.45 g / cm ³ or more, and an orientation degree of 85
% Or more, (BH) max value; A (MGOe) and i
Hc value; B have a total value A + B of 59 or more values (kOe), squareness ^{{(Br 2/4) /} (BH) max} is that it has a value of from 1.01 to 1.045 Characteristic R
-Fe-B based permanent magnet material.