JPH0817613A - Material alloy for manufacturing rare earth magnet powder and its manufacture - Google Patents

Abstract

PURPOSE:To improve resistance to oxidation, and enable preservation as material alloy, by making hydrogen compound of granular rare earth element whose average grain diameter is in a specific range exist in the base of alloy composed of rare earth element and transition metal. CONSTITUTION:Alloy composed of R (rare earth element containing Y) and T (transition metal) is held in a hydrogen atmosphere or a mixed gas atmosphere of hydrogen and inert gas, in the temperature range of about 750-1000 deg.C. Next the temperature is kept at about 100-700 deg.C which is more approximate than hydrogen occlusion treatment temperature, and the alloy is subsequently cooled at a room temperature. Thus granular hydride of R whose average grain diameter is about 0.002-20mum is made to exist in the base of the alloy composed of R and T. Thereby resistance to oxidation of material alloy is improved, and preservation and storage are enabled. Only by dehydrogenation of the material alloy, rare earth magnet powder excellent in magnetic characteristics can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a raw material alloy capable of producing a rare earth magnet powder only by a dehydrogenation treatment and a method for producing the same.

[0002]

2. Description of the Related Art R (rare earth element including Y), T (transition metal), D (semi-metal such as B and C), and M (Si, G)
a, Zr, Nb, Mo, Hf, Ta, W, Al, Ti,
V is one or more of V), rare earth magnet powders containing R and T, R and T and D or R, T, D and M as main components are known. R ₂ T ₁₇ , RT ₁₂ , RT ₅ , RT ₃ ,
There are rare earth magnet powders having an intermetallic compound phase such as RT ₂ as a main phase, and rare earth magnet powders having R, T and D as main components include rare earth magnets having an R ₂ T ₁₄ B intermetallic compound phase as a main phase. There are magnet powders and the like, and further, rare earth magnet powders containing R, T, D and M as main components include rare earth magnet powders having an R ₂ (T, M) ₁₄ B intermetallic compound phase as a main phase. Is also known.

The rare earth magnet powder containing R, T and D as main components or the rare earth magnet powder containing R, T, D and M as main components is an R-T-D alloy or R-T-D-M alloy. Ar
In a gas atmosphere, the temperature is kept at 600 to 1200 ° C. to perform homogenization treatment, or without homogenization treatment, the RTD alloy or RTDM alloy is used as H ₂ gas or H ₂ gas. The temperature was raised from room temperature to a temperature of 5 in a mixed atmosphere of
After holding at 0 to 1000 ° C. for H ₂ occlusion treatment, in a vacuum atmosphere or an inert gas atmosphere, temperature: 500 to
It is produced by holding at 1000 ° C. for de-H ₂ treatment, then cooling and crushing. It is also known that the internal structure of the rare earth magnet powder thus obtained becomes a fine and uniform recrystallized texture of the rare earth intermetallic compound, and its magnetic properties are significantly improved.

In the process of forming a fine and uniform recrystallized texture of a rare earth intermetallic compound, for example, R-
The Fe-B alloy is kept at a temperature of 500 to 1000 ° C. in the atmosphere of H ₂ gas or a mixed atmosphere of H ₂ gas and an inert gas to produce H.
_{2 When the} occlusion treatment is performed, a phase transformation is performed to R ₂ Fe ₁₄ B (H _x ) → RH ₂ + Fe + Fe ₂ B, and subsequently, H ₂ treatment is performed in the same temperature range, RH ₂ + Fe + Fe ₂ B → R ₂ Fe ₁₄ B (H It is also known that a recrystallized texture of fine rare earth intermetallic compound phase is formed by retransformation into _x ).
29702, JP-A-3-129703, JP-A-4-253304, JP-A-4-245403.
(See the bulletin, etc.) The formation of recrystallized texture of the fine rare-earth intermetallic compound phase by performing the phase transformation by the H ₂ storage treatment and the de-H ₂ treatment as described above means that R ₂ Fe
₁₇ , R (Fe, Ti) ₁₂ based magnet materials are also disclosed (Japanese Patent Laid-Open No. 4-260302 and Japanese Patent Laid-Open No. 4-34).
(See Japanese Patent Publication No. 8002).

The temperature of the Nd-Fe-B alloy is 500 in H ₂ gas or a mixed atmosphere of H ₂ gas and an inert gas.
It has also been confirmed that when H _{2 is} occluded while being held at ˜1000 ° C., a structure in which 0.2 to 0.5 μm of NdH ₂ is dispersed in the matrix (General Lecture of Autumn Meeting of the Japan Institute of Metals 19891, (See P367).

[0006]

However, the conventional temperature:
After holding at 500 to 1000 ° C. for H ₂ occlusion treatment,
In the manufacturing method in which the same temperature is subsequently maintained and H ₂ is removed, (a) the atmosphere in the same container is changed to H ₂ gas or H ₂ gas.
_{It is} necessary to convert from a mixed atmosphere of ₂ gases and an inert gas to a vacuum atmosphere, and when switching to a vacuum atmosphere, high temperature hydrogen reacts with the air remaining inside the machine such as a rotary pump, which may cause an explosion. (B) Since the phase decomposition is an exothermic reaction in the H ₂ occlusion treatment step and the recombination in the de-H ₂ treatment step is an endothermic reaction, continuous heat treatment causes a thermal change due to a change in rare earth metal. There is a problem that the recrystallization texture of the intermetallic compound cannot be controlled and abnormal grain growth occurs, so that a uniform and fine recrystallization texture cannot be obtained.

[0007]

Means for Solving the Problems Accordingly, the present inventors have:
As a result of research to solve such problems, the RT alloy or the RTM alloy was heated from room temperature in an atmosphere of H ₂ gas or a mixture of H ₂ gas and an inert gas at a temperature of 7
After holding at 50 to 1000 ° C. for H ₂ occlusion treatment, 100 to 700 which is relatively lower than the hydrogen occlusion treatment temperature.
The alloy kept at a predetermined temperature within the range of ℃, and subsequently cooled to room temperature has an average grain size of 0.002 to 0.002 in the alloy base.
A structure in which 20 μm granular R hydrides are dispersed is generated, and an alloy having such a structure is also improved in oxidation resistance and therefore can be stored as a raw material alloy. This raw material alloy is prepared in advance and stored. In addition, if a predetermined amount is taken out, charged into another vacuum furnace, and kept at a temperature of 500 to 1000 ° C. for a de-H ₂ treatment, the danger associated with the conversion of the atmosphere and the H ₂ occlusion treatment process phase degradation can prevent abnormal grain growth of recrystallized structure of a rare earth intermetallic compounds with the endothermic reaction by recombination in the exothermic reaction and deprotection H ₂ treatment steps, superior rare earth magnet powder in the magnetic properties than conventional We have obtained the knowledge that can be manufactured.

The present invention has been made on the basis of the above findings, and (1) an average particle size of 0.00 is formed in a base material of an alloy of R and T or an alloy of R, T and M.
A raw material alloy for producing a rare earth magnet powder having a structure in which a granular R hydride of 2 to 20 μm is present,
(2) The alloy composed of R and T or the alloy composed of R, T and M was maintained at a predetermined temperature within a range of 750 to 1000 ° C. in a hydrogen atmosphere or a mixed gas atmosphere of hydrogen and an inert gas. Then, a method for producing a raw material alloy for producing a rare earth magnet powder, which is further maintained at a predetermined temperature in the range of 100 to 700 ° C. lower than the hydrogen storage treatment temperature, and subsequently cooled to room temperature, characterized by: Is.

The average particle size of the granular R hydride dispersed in the raw material alloy base is preferably in the range of 0.002 to 20 μm, and more preferably 0.002 to 0.002 μm.
3 μm, more preferably 0.002 to 1 μm. The larger the amount of granular R hydrides deposited, the more preferable, and it is preferable that the amount is 50 vol% or more in the matrix.

The alloy composed of R and T or the alloy composed of R, T and M is kept at a predetermined temperature within a range of 750 to 1000 ° C. in a hydrogen atmosphere or a mixed gas atmosphere of hydrogen and an inert gas. After the hydrogen storage treatment, the temperature is maintained at a predetermined temperature in the range of 100 to 700 ° C., which is lower than the hydrogen storage treatment temperature. Hold temperature after hydrogen storage is 100 ℃
If it is less than 700 ° C. or exceeds 700 ° C., the hydride of R may not be granular or may have a dispersed structure, and even if dehydrogenated, excellent magnetic properties cannot be obtained, which is not preferable. Therefore, the holding temperature after hydrogen storage treatment is 1
It was set at a predetermined temperature within the range of 00 to 700 ° C. 750
To 400 ° C, which is lower than the hydrogen storage temperature, after being stored at a predetermined temperature in the range of up to 900 ° C for hydrogen storage treatment.
More preferably, the temperature is maintained at a predetermined temperature within the range of 700 ° C. As the starting raw material for producing the raw material alloy of the present invention, any alloy such as a casting alloy, a sintered alloy, a super-quenched alloy, an atomized alloy, a partially or wholly amorphous alloy, a mechanical alloy alloy, and a co-reduced powder is used. May be. Among them, it is particularly preferable to use a cast alloy, a part or all of an amorphous alloy, or a mechanical alloy alloy.

[0011]

【Example】

Examples 1 to 9 and Comparative Examples 1 to 4 In an Ar gas atmosphere, a plasma arc melting furnace was used to melt an alloy having the composition of components shown in Table 1, and casting was performed to form an ingot A
~ I was prepared.

[0012]

[Table 1]

The ingots A to I shown in Table 1 were homogenized under the conditions shown in Table 2 in an argon atmosphere, or were crushed into the sizes shown in Table 2 without any treatment, and then in a hydrogen atmosphere at 1 atm. The temperature and time retention conditions shown in Table 2 below after the first treatment of the hydrogen storage treatment at a temperature and time retention shown in Table 2 and further lower than the hydrogen storage treatment temperature in a hydrogen atmosphere at 1 atm. Second treatment, and subsequently cooled to room temperature under the conditions shown in Table 2 to obtain the raw material alloy 1 of the present invention.
-9 and comparative raw material alloys 1-4 were produced. The structures of these raw material alloys were observed with a scanning electron microscope or a transmission electron microscope, and the average particle size of granular R hydrides dispersed in the raw material alloy base was measured. The results are shown in Table 2. In the comparative example material alloy 3, 40% of granular R hydride was aggregated, and in the comparative example material alloy 4, granular R hydride was aggregated, and the average particle size could not be measured. The raw material alloy 5 of the present invention obtained in Example 5 was microscopically observed with a transmission electron microscope. A metallographic photograph of the transmission electron microscope is shown in FIG. A sketch drawing is shown in FIG.

[0014]

[Table 2]

After the raw material alloys 1 to 9 of the present invention and the comparative raw material alloys 1 to 4 were charged into another vacuum furnace and the temperature and time shown in Table 3 were maintained for dehydrogenation,
If necessary, nitriding treatment was performed under the conditions shown in Table 3, and then pulverization was performed to prepare a rare earth magnet powder having a uniform and fine recrystallized texture of the rare earth intermetallic compound. Measure the residual magnetization and coercive force of this magnet powder with a vibrating sample type magnetometer,
The results of these measurements are shown in Table 3.

[0016]

[Table 3]

Conventional Examples 1 to 3 The ingots E, G, and I in Table 1 were homogenized under the same conditions as in Examples 5, 7, and 9, or were crushed into the sizes shown in Table 4 without the homogenization. Then, the first treatment of hydrogen storage treatment was carried out by holding the temperature and time shown in Table 4 in a hydrogen atmosphere, and while being kept in the same container as it was, it was cooled to room temperature without performing the second treatment, and subsequently the same. After performing dehydrogenation treatment by keeping the temperature shown in Table 5 for a time shown in Table 5 in a container, if necessary, nitriding treatment was performed under the conditions shown in Table 5, and then pulverization was performed to obtain a rare earth intermetallic compound. A rare earth magnet powder having a recrystallization texture was prepared. The residual magnetization and coercive force of this rare earth magnet powder were measured with a vibrating sample magnetometer, and the measurement results are shown in Table 5.

[0018]

[Table 4]

[0019]

[Table 5]

When Examples 1 to 9, Comparative Examples 1 to 4 and Conventional Examples 1 to 3 are compared, the raw material alloys 1 to 9 of the present invention obtained in Examples 1 to 9 are used as raw material alloys and dehydrated. It can be seen that the remanent magnetization and coercive force of the rare earth magnet powder obtained by the elementary treatment are superior to those of the rare earth magnet powders obtained in Conventional Examples 1 to 3. However, the average particle size of the granular R hydride dispersed in the raw material alloy base material is out of the range of 0.002 to 20 μm, or the second treatment temperature is 100 to
It can be seen that the rare earth magnet powders obtained by using the raw material alloys obtained in Comparative Examples 3 to 4 which deviate from 700 ° C. cannot obtain sufficient residual magnetization and coercive force.

Examples 10 to 12 In an Ar gas atmosphere, a plasma arc melting furnace was used to prepare alloys having the component compositions shown in Table 6, and the resulting molten metal was melted into a single roll liquid. Ultra-quick cooling is performed in a quenching device to produce an amorphous ribbon, and the amorphous ribbon is crushed to obtain a powder J having an average particle size shown in Table 6.
~ L was produced.

[0022]

[Table 6]

The powders J to L were subjected to a first hydrogen storage treatment by maintaining the pressure and temperature shown in Table 7 for a time shown in Table 7 in a hydrogen atmosphere. The second treatment of holding is performed under the conditions of pressure, temperature and holding time shown in Table 7 which are relatively lower than the storage temperature, and subsequently cooled to room temperature under the conditions shown in Table 7 to obtain the raw material alloy powder of the present invention. 10-12 were produced.
The structures of these raw alloy powders were observed with a scanning electron microscope or a transmission electron microscope, and the average particle size of granular R hydrides dispersed in the raw alloy powder matrix was measured. The results are shown in Table 8. .

These raw material alloy powders 10 to 12 of the present invention were charged into another vacuum furnace, and the dehydrogenation treatment was carried out by maintaining the pressure and temperature shown in Table 8 for the time shown in Table 8 to obtain a uniform and fine powder. A rare earth magnet powder having a recrystallized texture of a rare earth intermetallic compound was prepared. In addition, in Example 10, the nitriding treatment was continued in nitrogen gas at 450 ° C. for 50 hours. The residual magnetization and coercive force of this rare earth magnet powder were measured with a vibrating sample magnetometer, and the measurement results are shown in Table 8.
It was shown to.

Conventional Examples 10 to 12 Powders J to L shown in Table 6 were subjected to the first treatment under the same conditions as in Examples 10 to 12 without being subjected to the second treatment, and were stored in the same container as they were while the hydrogen storage temperature was maintained. To room temperature, followed by dehydrogenation by maintaining the pressure, temperature and time shown in Table 7, and then pulverizing to obtain a rare earth magnet powder having a uniform and fine recrystallized texture of rare earth intermetallic compound. It was made. Regarding Conventional Example 10, the nitriding treatment was continued at 450 ° C. for 50 hours in nitrogen gas. The residual magnetization and coercive force of this rare earth magnet powder were measured with a vibrating sample magnetometer, and the measurement results are shown in Table 8.

[0026]

[Table 7]

[0027]

[Table 8]

[0028]

EFFECTS OF THE INVENTION Examples 10-12 and Conventional Examples 10-1
When comparing No. 2, the residual magnetization and coercive force of the rare earth magnet powder obtained by transferring the raw material alloy powders 10 to 12 of the present invention obtained in Examples 10 to 12 to another vacuum furnace and performing dehydrogenation treatment, It is understood that the rare earth magnet powders obtained in Conventional Examples 10 to 12 are excellent in residual magnetization and coercive force.

As mentioned above, according to the present invention, RT
The alloy or the R-T-M alloy is heated from room temperature in a H ₂ gas or a mixed atmosphere of H ₂ gas and an inert gas, and the temperature:
After holding at 750 to 1000 ° C. for H ₂ occlusion treatment and then maintaining at a predetermined temperature within the range of 100 to 700 ° C. lower than the hydrogen storage treatment temperature, subsequently cooling to room temperature,
A raw material alloy having a structure in which granular R hydrides having an average particle diameter of 0.002 to 20 μm are dispersed in the alloy base is prepared in advance and stored, and a predetermined amount of the raw material alloy is taken out and another vacuum is produced. When charged in a furnace, heated at a temperature of 500 to 1000 ° C. and held to remove H ₂ from it, rare earth magnet powder having better magnetic properties than before can be produced, which is an excellent industrial effect. Is.

[Brief description of drawings]

FIG. 1 is a transmission electron microscope photograph of a metal structure of a raw material alloy of the present invention.

FIG. 2 is a drawing of a metallic structure when the structure is observed with a transmission electron microscope.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takuo Takeshita 1-297 Kitabukurocho, Omiya City, Saitama Prefecture Central Research Laboratory, Mitsubishi Materiality Co., Ltd.

Claims (3)

[Claims] 1. When R (rare earth element containing Y) and T (transition metal) are used, the average particle diameter in the alloy base material composed of R and T:
A raw material alloy for producing a rare earth magnet powder, which has a structure in which 0.002 to 20 µm of granular R hydride is dispersed. 2. R (rare earth element including Y), T (transition metal), and further M (Si, Ga, Zr, Nb, Mo, H).
f, Ta, W, Al, Ti, and V), the average particle size in the alloy base material consisting of R, T, and M: 0.002
A raw material alloy for producing a rare earth magnet powder, which has a structure in which granular R hydrides having a particle size of ˜20 μm are dispersed. 3. An alloy consisting of R and T, or R, T
The alloy consisting of M and M is stored at a predetermined temperature in the range of 750 to 1000 ° C. in a hydrogen atmosphere or a mixed gas atmosphere of hydrogen and an inert gas, and is subjected to hydrogen storage treatment, and then lower than the hydrogen storage treatment temperature. A method for producing a raw material alloy for producing a rare earth magnet powder, which is characterized by holding at a predetermined temperature within a range of 100 to 700 ° C. and subsequently cooling to room temperature.