JPH03146608A - Manufacture of rare earth magnet alloy powder having excellent magnetic anisotropy - Google Patents

Abstract

PURPOSE:To stably manufacture rate earth magnet alloy powder having excellent magnetic anisotropy by executing hydrogen treatment of hydrogen occlusion- dehydrogenation under the specific condition to alloy containing the rear earth elements and Fe and B as the main components, cooling and pulverizing it. CONSTITUTION:Homogeneous treatment is executed to a block-like alloy ingot 2 composed of atomic percent of 8-30% rare earth elements containing Y, 3-15% B, and as necessary, 0.01-40% Co and the balance of Fe with inevitable impurities at about 600-1200 deg.C. Successively, the ingots 2 are packed into a vessel 3 in a heat holding furnace 4 together with spherical heat reserving material 1 (alumina, magnesia, etc.) and atmosphere in the furnace is made to hydrogen atmosphere and the temp. in there is raised and held to at 750-950 deg.C to occlude the hydrogen. Following to this, the atmosphere in a heat holding furnace 4 is made to vacuum atmosphere and held to at 750-950 deg.C, and after executing dehydrogenation treatment, this is cooled and pulverized. By this method, the rear earth magnet alloy powder having simple stabilization and excellent magnet anisotropy, is obtd.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is based on a rare earth element containing Y (hereinafter referred to as R) and a component in which Fe or a part of Fe is replaced with Co (hereinafter referred to as T). ) and an alloy containing B as the main component (hereinafter referred to as R-T
The present invention relates to a method for producing R-T-B-based magnet alloy powder having excellent magnetic anisotropy by subjecting a B-based alloy to a hydrogen treatment process of hydrogen absorption and dehydrogenation.

[Conventional technology]

In general, 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-1-132108. .

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
An R-T-B alloy ingot having R2T14B phase as a main phase or a pulverized powder of the ingot is subjected to a homogenization treatment or is not homogenized and is heated to H2 in a predetermined high temperature range.
This is a method in which the R2T14B phase is generated again by holding in an atmosphere to absorb H2, then evacuation while maintaining the same high temperature range, and removing H2 in a vacuum atmosphere. T-B magnet alloy powder is
Average particle size: 0.05-50x extremely fine R2T1
It has a texture whose main phase is a recrystallized structure of 4B phase, and has magnetic anisotropy.

[Problem that the invention seeks to solve]

The R-T-B magnet alloy powder produced by the above conventional method is
Although it has excellent magnetic anisotropy, due to slight variations in the alloy composition of the ingot and processing conditions such as H occlusion and deH2 removal, the magnetic anisotropy of the obtained R-T-B magnet alloy powder may change. In some cases, the magnetic anisotropy may be significantly reduced, and the magnetic anisotropy may vary. If such a situation occurs when mass producing the above-mentioned R-T-B type magnet alloy powder, a great deal of damage will be incurred.

Therefore, in order to stably obtain excellent magnetic anisotropy, it is necessary to perform hot plastic working such as roll rolling of the above-mentioned R-T-B magnet alloy powder. R-T-B which imparts magnetic anisotropy by performing plastic working
The manufacturing process of magnet alloy powder has problems such as being complicated and expensive.

[Means to solve the problem]

Therefore, the present inventors have developed a method for achieving stable and excellent magnetic anisotropy without reducing the magnetic anisotropy or causing variations in the magnetic anisotropy, and without performing the hot plastic working. As a result of research to produce RTB magnet alloy powder with orientation, (a) Temperature = 750 to 950°C
In the H2 atmosphere, the R2T14B phase of the R-T-B alloy ingot or powder is R2Tl4B-eRH2+T+T2B...
...The phase transformation of (1) occurs, followed by a deH2 step at the same temperature, RH+T+T2B→R2T14B...
...The phase transformation in (2) results in a recrystallized texture of the R2T 14 B phase again, but since the reaction in equation (2) above is an endothermic reaction, a temperature drop fluctuation occurs, and this temperature drop fluctuation When this occurs, the magnetic anisotropy of the recrystallized texture obtained through the phase transformations of equations (1) and (2) above decreases, and the magnetic anisotropy of the R-T-B alloy ingot or powder as the raw material decreases. It has been clarified that differences in temperature drop fluctuation occur depending on the filling location in the container, which causes variations in the magnetic anisotropy of the obtained R-T-B magnet alloy powder, and the above-mentioned To prevent temperature drop fluctuations,
When the above R-T-B alloy ingot or powder is heated together with a heat storage material to a high temperature in an H2 atmosphere and then held in a vacuum atmosphere at the same temperature, the temperature drop fluctuation due to the endothermic reaction in (2) above is caused by the above heat storage material. (b) The R- The component composition of the T-B alloy ingot or powder is R
:8~30%.

B: 3-15%.

R-T containing T and the remainder consisting of T and inevitable impurities
-B alloy may be used, but the above alloy further includes: (1) Ga: 0.01 to 5. (1%.

(ll) One or two of Zr and Hf = 0.0
1-3.0%.

(iii) Ga, one of Z' and Hf, or 2FJ: 0.01 to 5.0%.

R- containing any one of the above (1) to (iii)
When a T-B alloy is used, R with even better magnetic anisotropy can be obtained.
-T-B based magnet alloy was obtained.

This invention was made based on the above findings, and includes an R-T-B alloy that has been homogenized at a temperature of 600 to 1200°C as a pretreatment as necessary, together with a heat storage material.
R-T-B magnet alloy powder with excellent magnetic anisotropy, which is maintained in an H2 atmosphere at a temperature of 750 to 950°C, then held in a vacuum atmosphere at the same temperature, then cooled and crushed. The R-T-B magnet alloy powder obtained in this way can be further heat-treated at a temperature of 300 to 1000°C to obtain even better magnetic properties. be.

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

(1) The R-T-B alloy used as the raw material for the R-T-B alloy is generally in the form of an ingot or a bulk, but other types such as flakes,
It may have any shape such as powder, and its component composition is (a) R: 8 to 30% in atomic percentage.

B: 3-15%.

(b) R: 8 to 30%.

B: 3-15%.

Contains, and furthermore, Ga: 0.01-5.0%.

(c) R: 8 to 30%.

B: 3-15%.

Contains, and furthermore, Ga: 0.01-5.0%.

18 or 2 of Z' and Hf: 0.01 to 3.
0%.

(d) R: 8 to 30%.

B: 3-15%.

2" and one or two of Hf: 0, O2N2.
0%.

Any one of the above (a) to (d) may be used.

R is one or more rare earth elements including Y, and Nd, Pr, or a mixture thereof is particularly preferable; when it is lower than 8% and when it is higher than 30%, the coercive force decreases and high Characteristics cannot be obtained.

If B is lower than 3% or higher than 15%, the coercive force decreases and high characteristics cannot be obtained.

Ga, Zr, and Hf are elements that improve magnetic anisotropy and coercive force, but their effects are not noticeable when the content of these elements is less than 0.01%.On the other hand, when Ga is 5.0% %
If it is higher, or if Zr and Hf are higher than 3.0%, the magnetization value and coercive force decrease and high characteristics cannot be obtained.

The remaining T is a component in which Fe or a part of Fe is replaced with Co. Part of Fe can be replaced with 0.01 to 40% Co, and part of the Fe can be replaced with Co. This makes it possible to improve corrosion resistance, magnetic properties, and magnetic temperature properties.

(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 6
00-1200°C, preferably 1050-1200°C. If the homogenization temperature is lower than 600°C, the homogenization process will take a long time, resulting in poor industrial productivity;
If the temperature exceeds 1200°C, it will melt, which is not preferable.

(3) Processing temperature in H2 atmosphere and vacuum atmosphere, R in H2 atmosphere at a temperature within the range of 500-1000℃
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 the above formulas (1) and (2) occur significantly particularly at 750 to 950°C, and a recrystallized texture with excellent magnetic anisotropy is obtained. Therefore, the processing temperature in H2 atmosphere and vacuum atmosphere is 750-950℃.
Established.

The recrystallized texture obtained in this manner is a recrystallized texture with an average recrystallized grain size of 0.05 to t, o as the main phase of R2T t4 B type interwing compound phase. is preferred.

(4) 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 aggregate alloy coexists with the aggregate 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 manufactured from any material with a high melting point that does not react with the R-T-B alloy in a hydrogen and vacuum atmosphere at 50°C, but in particular ceramics such as alumina, magnesia, and zirconia, or tungsten, molybdenum, and stainless steel. High melting point metallic materials such as steel are preferred. The heat storage material may have any shape as long as it can be separated from the obtained R-T-B magnet alloy powder, such as a plate, block, lump, or sphere.

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. , holding the temperature at a constant temperature within the range of 750 to 950"C to cause the R-T-B alloy ingot to absorb H2,
Subsequently, even if the atmosphere in the heating and holding furnace 4 is made into a vacuum atmosphere and the H2 removal process is performed, the holding temperature does not decrease or fluctuate due to an endothermic reaction due to the presence of the spherical heat storage material 1.

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

As shown in FIGS. 1 and 2, when an R-T-B alloy ingot is treated with H2 in the presence of a heat storage material,
Because the heat storage material has a large heat capacity, even if an endothermic reaction occurs during the H2 removal process, the holding temperature can be maintained at a constant temperature without decreasing or fluctuating.
B-based magnet alloy powder has no variation in magnetic anisotropy.

〔Example〕

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

, mtL and R-T-B alloy ingots A-P were held in an atmosphere of 1000° C. for 40 hours to perform homogenization treatment.

Examples 1 to IB Approximately 10 to 30
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 5ff111 were prepared, and these alumina balls were used as a heat storage material, and the weight ratio of R-T-B alloy block ingot: heat storage material - 1:1. The proportions shown in Figure 1 were coexisted in an alumina container, charged into a heating furnace, and the atmosphere in the heating furnace was hydrogen gas at 780 Torr.
After holding at 850℃ for 3 hours, continue to increase temperature to 850℃
The reactor was held for 1 hour to perform dehydrogenation, evacuated to a vacuum level of 10-5 Torr, and cooled.

Thereafter, the heat storage material is separated from the R-T-B alloy ingot by sieving, and the R-T-B alloy ingot is crushed in a brown mill in an Ar atmosphere until it becomes less than 500. , RTB 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 magnetic field of 20 KOe or in no magnetic field, at a temperature of 120°C.
Hold for 60 minutes to harden, and each anisotropic bonded magnet (
(molding in a magnetic field) and isotropic bonded magnet (molding in a non-magnetic field)
was created. The magnetic properties of the obtained bonded magnet are shown in Table 2.

Comparative Examples 1 to 1B R-T-B alloy ingots A-P shown in Table 1 were homogenized and divided into block shapes of approximately 10 to 30 m+w square. , treated in the same manner as in Examples 1 to 16 above without a heat storage material, and then pulverized,
An R-T-B based magnet alloy powder was produced, and a bonded magnet was produced using this RTB based magnet alloy powder in exactly the same manner as in Examples 1 to 16, and the magnetic properties of the obtained bonded magnet were were measured, and the measurement results are shown in Table 2.

From the results in Table 2, (1) When an R-T-B block-shaped ingot is subjected to H occlusion and H2 removal treatment using a heat storage material, it is possible to obtain a better result by forming it in a magnetic field than when a heat storage material is not used. Since both the anisotropic bonded magnet obtained by molding and the isotropic bonded magnet obtained by molding without a magnetic field have excellent magnetic properties, an R-T-B magnet alloy powder with high magnetic properties can be obtained.

(2) A bonded magnet made from an R-T-B magnet alloy powder having a component composition containing Ga, Zr, and H1' is an R-T magnet that does not contain H and does not contain Ga, Zr, or Hf.
- Since the magnetic anisotropy is superior to that of bonded magnets obtained from B-based magnet alloy powder, by adding Ga, Zr, and Hf, R-T-
A B-based magnet alloy powder is obtained.

I understand that.

Examples 17 to 22 and Comparative Examples 17 to 18 alloy compositions are "12.4PrO,2FcBaICo10.
1 An R-T-B alloy ingot of BB, 0 GaO, 5 was cut into a cube with one side f5 mm square, and R-
A block-shaped ingot of a T-B alloy was produced. The above ingot was subjected to homogenization treatment at 1150°C for 20 hours in an atmosphere of A.

On the other hand, a magnesia plate-like heat storage material having a purity of 99.9% and a thickness of 5 mm was prepared, and the above R-T-B alloy block ingot was mixed in a weight ratio as shown in FIG. So, R-T-B alloy block ingot: Heat storage material-1:
This container was placed in a heating furnace and heat treated for 3 hours under the H2 storage conditions shown in Table 3. Dehydrogenation was performed for 1 hour and the mixture was cooled. After that, the magnesia plate heat storage material is removed and the treated R-T-B alloy block ingot is
"It was ground in a disk mill in an atmosphere until it became 500 μs or less to obtain an R-T-B magnet alloy powder.

The obtained R-T-B magnet alloy powder was mixed with 2% epoxy resin, and heated in a magnetic field of 20 KOe with pressure crab 6To.
It was molded at n/c- and kept at a temperature of 120° C. for 60 minutes to harden, thereby producing an anisotropic bonded magnet.

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

From the results in Table 3, it can be seen that in the production of R-T-B magnet alloy powder, the temperature for H storage and deH2 treatment is 750 to 950.
It can be seen that excellent magnetic anisotropy can be imparted by maintaining the temperature within the range of .degree.

〔Effect of the invention〕

According to the production method of the present invention, by using a heat storage material, R-T-B magnet alloy powder that is more stable than before and has excellent magnetic anisotropy and isotropy with excellent magnetic properties can be obtained. Since the RTB system magnet can be made into a total magnet alloy powder, it can bring about a significant cost reduction and bring about excellent industrial effects.

[Brief explanation of the drawing]

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 (12)

[Claims] (1) A rare earth element containing Y (hereinafter referred to as R), Fe or a component in which a part of Fe is replaced with Co (hereinafter referred to as T), and an alloy mainly composed of B are used together with a heat storage material at a temperature :
After being maintained in a hydrogen gas atmosphere at 750 to 950°C,
A method for producing a rare earth magnet alloy powder with excellent magnetic anisotropy, which comprises subsequently holding the powder in a vacuum atmosphere at a temperature of 750 to 950°C, then cooling and pulverizing it. (2) An alloy containing R, T, and B as main components at a temperature of 800
Homogenization treatment was carried out by holding at ~1200℃, and the homogenized alloy containing R, T, and B as main components was held together with the heat storage material in a hydrogen gas atmosphere at a temperature of 750 to 950℃. , followed by temperature: 750-950
1. A method for producing rare earth magnet alloy powder with excellent magnetic anisotropy, which comprises holding the powder in a vacuum atmosphere at ℃, followed by cooling and pulverizing. (3) The alloy containing R, T, and B as main components has an alloy composition of R: 8 to 30%, B: 3 to 15%, and the remainder: Fe and unavoidable impurities. 3. The method for producing a rare earth magnet alloy powder having excellent magnetic anisotropy according to claim 1 or 2, wherein the powder is an alloy having an excellent magnetic anisotropy. (4) The alloy containing R, T, and B as main components has an alloy composition in atomic percentages of R: 8 to 30%, B: 3 to 15%, and Co: 0.01 to 40%. 3. The method for producing a rare earth magnet alloy powder having excellent magnetic anisotropy according to claim 1 or 2, wherein the alloy contains Fe and unavoidable impurities. (5) The alloy whose main components are R, T, and B has an alloy composition of R: 8 to 30% in atomic percentage. B: 3-15%. Ga: 0.01-5.0%. 3. The method for producing a rare earth magnet alloy powder having excellent magnetic anisotropy according to claim 1 or 2, wherein the alloy contains Fe and unavoidable impurities. (6) The alloy whose main components are R, T, and B has the following alloy compositions in atomic percentage: R: 8 to 30%, B: 3 to 15%, Ga: 0.01 to 5.0%, One or two of Zr and Hf: 0.01 to 3.
3. The method for producing a rare earth magnet alloy powder having excellent magnetic anisotropy according to claim 1 or 2, wherein the alloy contains 0%, and the balance consists of Fe and unavoidable impurities. (7) The alloy containing R, T, and B as main components has the following alloy composition in atomic percentage: R: 8 to 30%, B: 3 to 15%, and one or two of Zr and Hf: 0.01-3.
3. The method for producing a rare earth magnet alloy powder having excellent magnetic anisotropy according to claim 1 or 2, wherein the alloy contains 0%, and the balance consists of Fe and unavoidable impurities. (8) The alloy whose main components are R, T, and B has the following alloy compositions in atomic percentage: R: 8 to 30%, B: 3 to 15%, Ga: 0.01 to 5.0%, Co: 0.01-40%. 3. The method for producing a rare earth magnet alloy powder having excellent magnetic anisotropy according to claim 1 or 2, wherein the alloy contains Fe and unavoidable impurities. (9) The alloy whose main components are R, T, and B has the following alloy compositions in atomic percentage: R: 8 to 30%, B: 3 to 15%, Ga: 0.01 to 5.0%, One or two of Zr and Hf: 0.01 to 3.
0%, CO: 0.01-40%. 3. The method for producing a rare earth magnet alloy powder having excellent magnetic anisotropy according to claim 1 or 2, wherein the alloy contains Fe and unavoidable impurities. (10) The alloy whose main components are R, T, and B has the following alloy composition in atomic percentage: R: 8 to 30%, B: 3 to 15%, and one or two of Zr and Hf: 0.01-3.
0%, Co: 0.01-40%. 3. The method for producing a rare earth magnet alloy powder having excellent magnetic anisotropy according to claim 1 or 2, wherein the alloy contains Fe and unavoidable impurities. (11) A rare earth magnet alloy with excellent magnetic anisotropy according to any one of claims 1 to 10, wherein the alloy containing R, T, and B as main components is a pulverized ingot, bulk, flake, or powder. Powder manufacturing method. (12) The method for producing a rare earth magnet alloy powder with excellent magnetic anisotropy according to any one of claims 1 to 11, wherein the heat storage material is made of a high melting point material, preferably a ceramic or a high melting point metal material. .