JPH0417604A - Manufacture of rare earth element magnet alloy powder having excellent magnetic characteristic - Google Patents

Abstract

PURPOSE:To manufacture a rare earth element magnet alloy powder having excellent coercive force and remanence ratio by cooling and pulverizing after heating and holding an alloy composed of the specific ratios of rare earth element, B, Al, Fe, etc., in a hydrogen gas atmosphere and vacuum atmosphere under the specific condition. CONSTITUTION:The alloy composed of 8-30atm% the rare earth elements (R) containing Y, 3-15% B and further, 0.01-5.0atm% at least one kind among Al, Si and V and the balance of Fe with inevitable impurities is prepared. Temp. of this alloy is raised together with heat accumulating material (alumina, magnesia, etc.) under the hydrogen gas atmosphere, and after holding it under the hydrogen gas atmosphere at 750-950 deg.C, successively holding it under vacuum atmosphere at 750-950 deg.C, this is cooled and pulverized. By this method, the rare earth element magnet alloy powder having excellent magnetic characteristic, is easily and stably obtd.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention provides a rare earth element containing Y (hereinafter referred to as R) and a component in which a part of Fc or Fe is replaced with CO (hereinafter referred to as T). ), and with B as the main component, l, Sj, V
At least 18 or more of: 0.01 to 5.0 at%
(hereinafter referred to as R-T-B alloy) containing
The present invention relates to a method for producing an RTB magnet alloy powder having excellent magnetic properties, particularly coercive force and squareness, by hydrogen absorption-dehydrogenation treatment.

[Conventional technology]

Generally, a method for manufacturing an RTB-based magnet alloy powder by absorbing hydrogen in an RT-B-based alloy and then dehydrogenating it is disclosed, for example, in JP-A No. 1-132106. .

R-T-B disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 1-132106
The manufacturing method of the magnet alloy powder is as follows: R2T14B type intermetallic compound phase (hereinafter referred to as
A T-B alloy ingot having R2T14 B phase as its main phase or a pulverized powder of the ingot is subjected to a homogenization treatment or is not homogenized and subjected to H in a predetermined high temperature range.
This is a method in which the R2T14B phase is generated again by holding in a 2 atmosphere to absorb H2, then evacuating while maintaining the same high temperature range, and removing H2 in a vacuum atmosphere. -T-B magnet alloy powder has extremely fine R2 particles with an average particle size of 0.05 to 50 μm.
It has a texture whose main phase is a recrystallized structure of T14B phase,
It also has high magnetic properties.

[Problem to be solved by the invention]

The R-T-B magnet alloy powder produced by the above conventional method is
Although it has excellent magnetic properties, the alloy composition of the ingot, H
Due to slight variations in processing conditions such as occlusion and H2 removal, the magnetic properties of the obtained R-T-B magnet alloy powder, especially the coercive force and squareness, may vary or deteriorate. Ta. Products in which the coercive force and squareness vary or deteriorate must be disposed of, and if such a situation occurs in the case of industrial mass production, a great deal of damage will be incurred.

[Means to solve the problem]

Therefore, the present inventors have developed an R-T-B magnet alloy powder that has stable and excellent magnetic properties without causing variations or deterioration in the above-mentioned magnetic properties, especially coercive force and squareness. As a result of research to produce (a) R2T of R-T-B alloy ingot or powder in H2 atmosphere at a temperature of 750 to 950°C.
The 14B phase is RTB→RH+T+T2B (1
), followed by a deH2 step at the same temperature, R
H2+T+T2B→R2T14B ・・・・・・・・・
The phase transformation in (2) results in a recrystallized texture of the R2T14B phase again, but in order to uniformly carry out the reaction in equation (1) above on the R-T-B alloy ingot or powder without variations depending on location, The temperature raising process from the lowest temperature to the temperature of 750 to 950°C is often carried out in an H2 atmosphere, and since the reaction in equation (2) above is an endothermic reaction, temperature drop fluctuations occur. , when this temperature drop fluctuation occurs, the magnetic properties of the recrystallized texture obtained through the phase transformation of equations (1) and (2) above will decrease, and the R as the raw material
- Differences in temperature drop depending on the location where the T-B alloy ingot or powder is filled in the container causes variation and deterioration in the magnetic properties of the obtained R-T-B magnet alloy powder. It has been clarified that this is the case.

Therefore, in order to prevent the occurrence of the temperature drop fluctuation, the R-T-B alloy ingot or powder should be heated together with a heat storage material to a high temperature in an H2 atmosphere, and then held at the same temperature in a vacuum atmosphere. , the temperature drop fluctuation due to the endothermic reaction of the above equation (2) is prevented by the heat retention effect of the heat storage material, and the temperature is maintained at a constant high temperature.
- Eliminates deterioration and variation in magnetic properties of B-based magnet alloy powder.

(b) The composition of the R-T-B alloy ingot or powder as the raw material is R: 8 to 3 in atomic percentage.
0%, B: 3 to 15%, At least one of An), Sl, and V: 0.01 to
5.0%, with the remainder consisting of T and unavoidable impurities.
-B-based alloy (where T is Fe or a part of Fe is Co:
o, a component substituted with 01 to 40%), the sensitivity to the temperature drop fluctuation in the deH2 process becomes insensitive,
It is possible to obtain an R-T-B magnet alloy powder that has stable and excellent magnetic properties with little variation, particularly excellent coercive force and squareness.

The above findings (a) and (b) were obtained.

This invention was made based on the above knowledge, and the R-T-B alloy, which has been homogenized at a temperature of 600 to 1200°C as a pretreatment as necessary, is heated together with a heat storage material.
R-T-, which has excellent magnetic properties, is heated in a H2 atmosphere at a temperature of 750 to 950°C, then held in a vacuum atmosphere at the same temperature, and then cooled and crushed. It is characterized by the manufacturing method of B-based magnet alloy powder, and the R-T-B-based magnet alloy powder obtained in this way can be further heat-treated at a temperature of 300 to 1000°C to achieve even better magnetic properties. characteristics can be obtained.

Next, the reason for limiting the conditions in the manufacturing method of the present invention will be explained.

(L) R-T-B alloy The R-T-B alloy used as a raw material is generally in the form of an ingot or a bulk, but other types such as flakes,
It may have any shape such as a powder, and its component composition contains, in atomic percentage, Ra 8-30%, B 3-15%, and at least one of AN, Sl, and V: 0 .01~5
．． 0%, with the remainder consisting of T and unavoidable impurities. In the above R-T-B alloy, R is one or more rare earth elements including Y, or especially N
d, Pr or a mixture thereof is preferred, and other rare earth elements are added thereto, among which Tb is particularly preferred.

Dy has the effect of improving coercive force. R content is 8
If it is lower than % or higher than 30%, the coercive force will decrease,
High characteristics cannot be obtained.

B may be partially replaced with C, N, O, F,
If it is lower than 3% or higher than 15%, the coercive force decreases and high characteristics cannot be obtained.

Aj), Si, and V are elements that improve coercive force and squareness.When these elements are lower than 0.0196, the effect is not noticeable, and when higher than 5.0%, they reduce magnetization. The value and coercive force decrease, making it impossible to obtain high characteristics.

The remaining T is a component in which Fe or a part of Fe is replaced with Co. A part of Fe can be replaced with o, oi to 4o% of Co, and a part of the Fe can be replaced with Co. This makes it possible to improve corrosion resistance, magnetic properties, and magnetic temperature properties.

In addition, TI, Nb, Ta, Mo as necessary.

Even if at least one kind of W is added together with AN, Si, and V in a total amount of 5.0% or less, the effect of improving squareness can be obtained.

(2) Homogenization Treatment The above R-T-B alloy does not need to be homogenized, but by homogenizing it, the R-T-B magnet alloy powder can have more uniform magnetic properties. obtained and its temperature is 8
00-1200"C1 preferably 1050-1200℃
It is. If the homogenization temperature is lower than fioo"c, the homogenization process will take a long time, resulting in poor industrial productivity.
On the other hand, if the temperature exceeds 1200°C, it will melt, which is not preferable.

(3) Atmosphere during the heating process If the heating process from room temperature to maintaining the temperature at 50 to 950°C is carried out in an H2 atmosphere, compared to other vacuum or inert gas atmospheres such as Ar, The phase transformation of the above formula (1) tends to occur uniformly without variation.

(4) Processing temperature in H2 atmosphere and vacuum atmosphere
When the -T-B alloy is held, the phase transformation shown by equation (1) above occurs, and when it is subsequently held in a vacuum atmosphere at the same temperature, the phase transformation shown by equation (2) above occurs, and the recrystallization texture changes. However, the phase transformations of formulas (1) and (2) above occur significantly, especially at 750 to 950°C, and a recrystallized texture with excellent magnetic properties is obtained. Therefore, the processing temperature in the H2 atmosphere and vacuum atmosphere was set at 750 to 950°C.

The recrystallized texture obtained in this manner is preferably a recrystallized texture in which the main phase is an R2T14B type intermetallic compound phase with an average recrystallized grain size of 0.05 to 1.0.

(5) Heat storage material Since the above equation (2) is an endothermic reaction, 750 to 950
Even if the temperature is held at a constant temperature of °C, the holding temperature will fluctuate downward. When the above holding temperature decreases and fluctuates, the obtained R-
This is undesirable because the magnetic anisotropy of the T-B magnet alloy powder decreases or varies. In order to prevent the above-mentioned holding temperature drop fluctuations, it is possible to control the furnace temperature during the phase transformation in equation (2) above to prevent the holding temperature drop fluctuations. Control to prevent fluctuations in lowering of the holding temperature of T-B alloys is industrially difficult, and requires special equipment to sufficiently prevent fluctuations in lowering of the holding temperature, resulting in high costs.

Therefore, in this invention, a method is adopted in which the R-T-B alloy raw material is heated together with the heat storage material and maintained at a constant temperature within the above-mentioned range of 750 to 950°C.

When the above R-T-B alloy coexists with the heat storage material, even if the endothermic reaction of equation (2) occurs, the holding temperature of the R-T-B alloy does not decrease due to the heat retention effect of the heat storage material, and it is easy to The temperature can be maintained at a constant temperature within the range of 750 to 950°C. The heat storage material has a large heat capacity of 750 to 9
It may be made of any material with a high melting point that does not react with the R-T-B alloy in a 50"C hydrogen and vacuum atmosphere, but in particular ceramics such as alumina, magnesia, zirconia, or tungsten, molybdenum, High-melting point metal materials such as stainless steel are preferred.The shape of the heat storage material may be plate-like, block-like, lump-like,
It may have any shape as long as it can be separated from the obtained R-T-B magnet alloy powder, such as a spherical shape.

Next, the method for preventing a drop in holding temperature according to the present invention using a heat storage material will be specifically explained with reference to the drawings.

FIG. 1 is a cross-sectional explanatory diagram when a spherical heat storage material is used as a heat storage material, and FIG. 2 is a cross-sectional explanatory diagram when a plate-shaped heat storage material is used as a heat storage material, 1 is a spherical heat storage material, 1 ' is a plate-shaped heat storage material, 2 is an R-T-B alloy block ingot, 3 is a container, and 4 is a heating and holding furnace.

As shown in FIG. 1, an R-T-B alloy block ingot 2 is filled together with a spherical heat storage material 1 into a container 3 in a heating and holding furnace 4, and the atmosphere in the heating and holding furnace 4 is made into a hydrogen atmosphere. Even if the R-T-B alloy ingot is held at a constant temperature within the range of 750 to 950° C. to absorb H2, and then the atmosphere in the heating and holding furnace 4 is made into a vacuum atmosphere for H2 removal treatment, Due to the presence of the spherical heat storage material 1, the holding temperature does not decrease or fluctuate due to an endothermic reaction.

FIG. 2 shows the R-T
-B alloy block-shaped ingot 2 is sandwiched between plate-shaped heat storage materials 1' and subjected to H2 occlusion and H2 removal treatment in the same manner as shown in FIG.

As shown in FIGS. 1 and 2, when the R-T-B alloy ingot was treated with H2 in the presence of a heat storage material, the heat capacity of the heat storage material was increased. Therefore, even if an endothermic reaction occurs during the deH2 treatment process, the holding temperature can be maintained at a constant temperature without any decrease or fluctuation, and the obtained R-T-
B-based magnet alloy powder can prevent deterioration and variation in magnetic properties.

〔Example〕

The raw materials were melted in a plasma arc melting furnace and cast to produce R-T-B alloy ingots A-V having the composition shown in Table 1.

These R-T-B alloy ingots A-V were each held in an Ar atmosphere at a temperature of 1100° C. for 40 hours to perform a homogenization treatment.

Example 1 About 10 to 30 of the above R-T-B alloy ingot A-V
It was divided into mm square blocks to produce R-T-B alloy block ingots.

On the other hand, alumina balls with a purity of 99.9% by weight and a diameter of 5 mm were prepared, and the alumina balls were used as a heat storage material, and the weight ratio of the R-T-B alloy block ingot to the heat storage material was 1:1. They were coexisted in an alumina container at the ratio shown in Figure 1, charged into a heating furnace, and the atmosphere in the heating furnace was changed from room temperature to 760 Torr hydrogen gas, and the temperature was raised to 850°C for 3 hours in a 760 Torr hydrogen atmosphere. After holding the temperature, continue to hold the temperature at 850°C for 1 hour to perform dehydrogenation and reduce the vacuum level to + I x 10'T.
The mixture was evacuated until it reached orr and cooled.

Thereafter, the heat storage material and the R-T-B alloy ingot are separated by sieving, and the R-TB alloy ingot is ground in a brown mill in an Ar atmosphere until it has a particle size of 500 or less. A TB-based magnet alloy powder was obtained.

The obtained R-T-B magnet alloy powder was mixed with 3% by weight of epoxy resin and molded with a pressure crab of 6Ton/c- in a 20KOe magnetic field or in no magnetic field, at a temperature of 120°C, 6
The mixture was held for 0 minutes to cure, and a bonded magnet molded in a magnetic field and a bonded magnet molded in a non-magnetic field were produced, respectively. The magnetic properties of the obtained bonded magnet (magnetic flux density B', coercive force iHc, maximum energy product BHfllaX and squareness Hk/IH
(where Hk indicates the magnetic field when B rX is 0.9 on the 4πI-H curve), and those measurement results are
Shown in the table.

Comparative Example 1 R-T-B alloy ingots A to ■ in Table 1 were homogenized and divided into blocks of approximately 10 to 30 mm square. After processing in the same manner as in Example 1 above without the material, pulverization and R-T-
A B-based magnet alloy powder was produced, and a bonded magnet was produced using this R-T-B-based magnet alloy powder in exactly the same manner as in Example 1, and the magnetic properties of the obtained bonded magnet (magnetic flux density B',
Coercive force iHc, maximum energy product BHmax and squareness Hk/iHc However, Hk is Br on the 4πl-H curve
The magnetic field at X O,9) was measured, and the results are shown in Table 2.

From the results in Table 2, it can be seen that when the R-T-B block-shaped ingot was subjected to H2 occlusion and H2 desorption treatment using a heat storage material, the bond obtained by forming in a magnetic field was better than when no heat storage material was used. It can be seen that both the magnetic properties of the magnet and the bonded magnet obtained by molding without a magnetic field are excellent, particularly in coercive force and squareness.

Examples 2 to 7 and Comparative Examples 2 to 3 Alloy composition is Nd12.4PrO,2co1 in atomic percentage
An R-T-B alloy block ingot of 5.5" 0.5 FeBad was cut into cubes with one side or 15 mm square, and this ingot was heated to 1150°C. , homogenization treatment was performed in an Ar atmosphere for 20 hours.

On the other hand, a stainless steel plate with a purity of 99.9% and a thickness of 5 mm was prepared, and an R-T-B alloy ingot was placed in a container using this stainless steel plate as a heat storage material as shown in Figure 2. The R-T-B alloy block ingot is placed in a container at a ratio of -1 = 3 (weight ratio), and this container is charged into a heating furnace. Heat treatment was performed for 3 hours under the H22 storage conditions shown in Table 3, followed by dehydrogenation for 1 hour under the H2 removal conditions shown in Table 3, followed by cooling. After that, the stainless steel plate heat storage material was removed and the treated RT-B alloy block ingot was
The powder was pulverized in a disk mill in an r atmosphere until it had a particle size of 500 μm or less to obtain an R-T-B magnet alloy powder.

The obtained R-T-B magnet alloy powder was mixed with 2% by weight of epoxy resin, then press-molded with a pressure crab of 67 on/cd, held at a temperature of 120°C for 60 minutes, and hardened. A bonded magnet was produced.

The magnetic properties of the obtained bonded magnet are shown in Table 3.

From the results in Table 3, the H storage and deH2 treatment temperature was set to 75
R-T-B by maintaining within the range of 0 to 950℃
An isotropic bonded magnet manufactured using this R-T-B magnet alloy powder has a coercive force JHc.
However, if the H occlusion and H2 removal treatment temperature is lower than 750°C, sufficient coercive force iHc cannot be obtained, and on the other hand, if it exceeds 950°C, the magnetic properties are extremely deteriorated. I understand. Furthermore, it can be seen that not only non-metals such as ceramics but also heat-resistant alloys such as stainless steel can be used as the heat storage material used in the production of RTB magnet alloy powder.

〔Effect of the invention〕

According to the manufacturing method of the second invention, by using a heat storage material in H2 occlusion and H2 desorption processing, RT -B type magnet alloy powder can be obtained, which brings excellent industrial effects.

[Brief explanation of drawings]

FIGS. 1 and 2 are schematic cross-sectional views showing an embodiment of the present invention in which a container is filled with an R-T-B alloy block ingot and a heat storage material so as to coexist.

Claims (5)

[Claims] (1) Rare earth elements containing Y (hereinafter referred to as R): 8 to 3
0 atomic %, B: 3 to 15 atomic %, and at least one of Al, Si, and V: 0.01 to 5.
An alloy containing 0 atomic % and the remainder consisting of Fe and unavoidable impurities is heated in a hydrogen gas atmosphere together with a heat storage material,
Rare earths with excellent magnetic properties characterized by being held in a hydrogen gas atmosphere at a temperature of 750 to 950°C, then held in a vacuum atmosphere at a temperature of 750 to 950°C, then cooled and pulverized. Manufacturing method of magnet powder. (2) Contains R: 8 to 30 atom %, B: 3 to 15 atom %, and further contains at least one of Al, Si, and V: 0.01 to 5.
An alloy containing 0 atomic % and the remainder consisting of Fe and unavoidable impurities is homogenized at a temperature of 600 to 1200°C, and the homogenized alloy is placed in a hydrogen gas atmosphere together with a heat storage material. The temperature was raised at 750 to 950°C, and then maintained in a hydrogen gas atmosphere at a temperature of 750 to 950°C.
A method for producing rare earth magnet alloy powder with excellent magnetic properties, which comprises holding in a vacuum atmosphere at 50°C, then cooling and pulverizing. (3) The above alloy contains R: 8 to 30 atomic %, B: 3 to 15 atomic %, Co: 0.01 to 40 atomic %, and further contains at least one of Al, Si, and V: 0.01-5.
3. The method for producing rare earth magnet powder with excellent magnetic properties according to claim 1 or 2, wherein the alloy contains 0 atomic % of Fe and the remainder consists of Fe and unavoidable impurities. (4) The method for producing a rare earth magnet alloy powder with excellent magnetic properties according to claim 1, 2 or 3, wherein the alloy is a pulverized ingot, bulk, flake or powder. (5) The method for producing a rare earth magnet alloy powder with excellent magnetic properties according to claim 1, 2, 3 or 4, wherein the heat storage material is made of a high melting point material, preferably a ceramic or a high melting point metal material. .