JPH02194108A - Manufacture of alloy powder for rare earth metal magnet - Google Patents

Abstract

PURPOSE:To easily obtain powder having the prescribed particle size in much quantity by reacting rare earth metal or alloy thereof with hydrogen at the specific temp., embrittling and, after that, pulverizing. CONSTITUTION:By alloying raw material powder with mechanical alloying method, the alloy powder for rare earth metal magnet composed of the rare earth metal - transition metal - metalloid is manufactured. Then, the rare metal or the alloy thereof is embrittled by being reacted with hydrogen at 300 - 1,000 deg.C, and after that, this is pulverized to make the raw material powder. In this result, a uniform alloy powder for magnet can be mass-produced, and the good yield is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing rare earth alloy powder for magnets, and more particularly to a method for obtaining alloy powder for magnets by alloying raw material powders by a mechanical alloying method.

(Prior art) Rare earth gold m (R)-transition gold B such as Nd-Fe-B magnets
(T) - Hankin Ji! Conventionally, the sintering method and the ultra-quenching method are known as methods for manufacturing (M)-based magnets.

Although the sintering method is already in practical use, this method has the disadvantage that it is difficult to obtain products with special and complex shapes or powder for bonded magnets.

On the other hand, the ultra-quenching method is suitable not only for the production of bulk materials but also for the production of powder for bonded magnets, but on the other hand, there are problems in terms of the uniformity of the obtained powder, yield, and productivity.

In the ultra-quenching method, the molten alloy is dropped from a nozzle onto a rotating roll to be ultra-quenched, then crushed, heat-treated, and passed through to obtain powder for magnets. In addition, when dropping the molten alloy from the nozzle onto the roll, it cannot be used if the molten alloy remains in the nozzle, the molten alloy that has fallen onto the roll splashes, or if the cooling by the roll is not effective. Otherwise, the yield will be poor. Furthermore, when molten alloy is dropped onto a roll surface, the cooling rate of the molten alloy is not necessarily uniform, resulting in a mixture of molten alloy that cooled well and molten alloy that did not. There were also problems with this.

For this reason, mechanical alloying methods have recently been developed and studied as a technology for producing 1-alloy powder. This mechanical alloying method
As disclosed in Japanese Patent Application Laid-Open No. 62-240742, raw material powder is ground for a long time using a highly efficient ball mill or the like, and in the process, the powder is ground and alloyed at the same time.

(Raw I to be solved by the invention) However, rare earth metals or rare earth metals as raw materials -
Transition metal alloys are very ductile, and the methods used to obtain their powders, such as producing shavings by sawing or filing, are impractical from an industrial production perspective and can be difficult to obtain. There was a serious problem that the raw material powder was oxidized.

Further, during the mechanical alloying process, the powder becomes a fine powder of several meters in size, so there is a problem that oxidation from the atmosphere cannot be avoided even if careful attention is taken.

(Means for Solving the Problems) The present invention has been made to solve the above problems, and its gist is to form a rare earth metal-transition metal semi-alloy by alloying raw material powder by a mechanical alloying method. When producing an alloy powder for island earth magnets made of metal, the rare earth metal or its alloy is made to embrittle by reacting with hydrogen at a temperature of 300 to tooo Celsius, and then pulverized to form the raw material powder. There is a particular thing.

In the present invention, Nd or P is normally used as the rare earth metal, but low-source Ce or ffi crystalline earth metals such as Dy and Tb may be included for coercivity and E.

In the present invention, such a rare earth metal is powdered alone or in the form of an alloy with other components, and this is used as a starting powder for mechanical alloying treatment. The method for obtaining the powder is characterized by hydrogenating the rare earth metal or its alloy to embrittle it, and then pulverizing it. The alloy form is preferably a rare earth metal-transition metal alloy, where the transition metals include Fe, F,
e-Go etc. are effective. Even when rare earth metals are hydrogenated in the form of such alloys, the same effects as when hydrogenating rare earth metals alone can be obtained, and in this case, there is an advantage that raw materials can be obtained at low cost.

In the present invention, the above hydrogenation treatment is carried out at a temperature of 300 to 100
It is carried out in the range of 0°C, preferably in the range of 700 to 900°C. If the temperature is lower or higher than this, the reaction will not proceed properly.

Further, it is effective to pressurize the hydrogen to 1 atm or more, but 1 atm is usually sufficient. 11! The flow rate of hydrogen is
Depending on the amount of rare earth metal or its alloy, usually 2 to 5
Emperor/minute is fine.

When the reaction is allowed to take place under these conditions for a predetermined period of time (for example, about 30 minutes to 2 hours) and then cooled, the rare earth metal or its alloy has become brittle due to hydrogenation at this stage. For example, it is coarsely crushed using a show crusher or the like.

As a result, a powder having a predetermined particle size (for example, less than 11 mm) can be easily obtained. Note that this operation is preferably performed in an inert gas to prevent ignition.

Once a rare earth metal or its alloy powder is obtained in this way, the first step is to prepare a separately prepared metal powder (for example, Fa,
Mainly Co, Fe-Co alloys, powders of pure metals or alloys such as AI, Ti, Nb, Zr, V, Cr, Ga may be mixed to improve properties) and semimetals (
Performing mechanical alloying treatment with B as the main component (which may also be in the form of an alloy such as C, Si, S, P or Fe-B),
A grinding machine such as a pole mill or an attriter is used for this mechanical alloying treatment. In particular, it is advantageous to use a high-energy type mill such as a planetary ball mill or a vibrating ball mill because the processing time is shortened.

This mechanical alloying treatment is preferably carried out in a non-oxidizing atmosphere by introducing an inert gas or a suitable liquid (heptane, hexane, etc.) inside to prevent oxidation of the powder.

It should be noted that it is also possible to dehydrogenate the rare earth metal or its alloy powder that has been hydrogenated by the above procedure by evacuation at a high temperature prior to the mechanical alloying treatment. It has been confirmed that even if mechanical alloying treatment is directly performed without performing elementary treatment, alloying of rare earth metals and other components will proceed. Moreover, it was confirmed that the oxidation of highly active rare earth metals was suppressed at that time, and it was therefore found that it is more convenient to carry out the dehydrogenation treatment after the mechanical alloying treatment, rather than before.

Now, mechanical alloying treatment is usually carried out for a period of 1 hour to 40 hours, depending on the type of grinder used and other conditions, and during this time the starting powder is finely pulverized and the coagulation 1 alloy formation is not performed. Crystallization progresses.

The powder thus obtained is heated to an appropriate temperature (e.g. 4
00~700℃), the ferromagnetic compound R7T
Fine precipitation of 14B phase and dehydrogenation occur. The resulting powder can be suitably used as an alloy powder for bonded magnets.

In addition, if a high-temperature densification treatment such as hot pressing or HIP is performed instead of heat treatment, an isotropic high-density magnet can be obtained, which can be further processed through upsetting and extrusion.

An anisotropic magnet can be obtained by performing hot plastic deformation such as rolling to align the axis of easy magnetization in any direction. Furthermore, by pulverizing this anisotropic magnet, powder for an anisotropic bonded magnet can be obtained.

(Operations and Effects of the Invention) As described above, the present invention provides rare earth metals or alloy powders thereof, which are used as starting powders for mechanical alloying, through embrittlement treatment through hydrogenation reaction and subsequent pulverization treatment. Therefore, powder with a predetermined particle size can be easily obtained in large quantities, and the yield rate is also high. In addition, the stratification reaction of the powder can be suppressed during the pulverization process, and the powder produced in this way can also be mechanically alloyed as it is.
It is Noh. In this case, oxidation of the powder during mechanical alloying treatment can also be prevented.

As described above, according to the present invention, uniform alloy powder for magnets can be mass-produced, and the yield is good.

In the process of manufacturing rare earth magnets from this alloy powder, dehydrogenation treatment is ultimately necessary, but heat treatment, hot pressing, HIP, etc. are required to manufacture magnets from alloy powder, and these treatments Since dehydrogenation can be carried out automatically if it is carried out in a vacuum, it is not necessary to separately provide a special treatment step for dehydrogenation.

On the other hand, the magnet obtained by this method contains less oxygen,
Shows good properties as a magnet.

(Example) Next, in order to clarify the characteristics of the present invention, examples thereof will be described in detail below.

[Example 1] Nd metal (99-9%) was placed in a hydrogen treatment furnace, and after evacuation, Ar22 inspection was performed and the temperature was raised to 800°C.

H2 gas was flowed into the mixture three times/part, and the reaction was allowed to proceed for 1 hour. When it was then cooled and taken out, it was found that Nd reacted with H2 to form a hydride and became brittle. Therefore, this was coarsely ground to 40 meshes or less in a glove box with an Ar atmosphere. This pulverized product and each powder of Fe, Go, and H (4
0 mesh or less) with a multilayer ratio of 3 ONd -64Fe
-5Co -I B were weighed and placed in a planetary ball mill with an inner diameter of 200 mm and a height of 200 mm.
It was put in together with a steel ball made of steel, the interior was made into an Ar atmosphere, the atmosphere was sealed, and a predetermined grinding process was performed. The grinding process was carried out for 4 hours, and the obtained powder was subjected to a vacuum process at 600°C, and then 2% by weight of epoxy resin was added and mixed, and this was press-molded to obtain an isotropic bonded magnet.

Separately, the obtained powder was hot-pressed at 750° C. for 1 minute to obtain an isotropic magnet. Furthermore, this was upset-processed at 750° C. until the height reached 173 to obtain an anisotropic magnet. Further, this anisotropic magnet was crushed, mixed with an epoxy resin, and further press-molded in a magnetic field to obtain an anisotropic bonded magnet. The properties of these magnets were measured and were as shown in Table 1.

[Comparative Example 1] Nd metal was cut into small pieces of about 0.5 mm by sanding, mixed with Fe, Co, and B powders in the same manner as in Example 1, and alloyed using a planetary ball mill. Example 1
Isotropic bonded magnets, hot-pressed magnets, upset magnets, and anisotropic bonded magnets were prepared in the same manner as above. When their properties were measured, they were as shown in Table 2.

[Example 2] Example of (Nd, Pr, Dy) -Fe master alloy! It was hydrotreated in the same manner as above and then crushed. This was mixed with ferroboron (Fe-B) and Co powder, and mechanically alloyed using a horizontal ball mill.
It was set to Ca-18.

The obtained powder was treated in the same manner as in Example 1 to obtain 4
When we obtained different kinds of magnets and measured their core characteristics, we found that
It was as shown in the table.

[Comparative Example 2] Instead of performing the hydrogenation treatment and its pulverization treatment in Example 2, the same mechanical alloying treatment was performed using lathe shavings of the (Nd, Pr, Dy) -Fe master alloy. Then, the obtained alloy powder was subjected to the same treatment as in Example 2, and the characteristics of the obtained Class 414 magnet were measured, as shown in Table 4.

It is clear from these results that all the magnets obtained by Suekan'Jl have low oxygen levels, improved compactness of the compact, high IOC, and a square demagnetization curve. It can be seen that it has good magnetic properties, such as (B)I) high self-JX.

Claims (3)

[Claims] (1) When producing an alloy powder for rare earth magnets consisting of rare earth metals, transition metals, and metalloids by alloying raw material powders by a mechanical alloying method, the rare earth metals or their alloys are hydrogenated at a temperature of 300 to 1000°C. 1. A method for producing an alloy powder for rare earth magnets, which comprises embrittling it by reacting with the powder and then pulverizing it to obtain the raw material powder. (2) The rare earth metal is in the form of an alloy with a transition metal at a temperature of 3
Claim (1) characterized in that the alloy powder is reacted with hydrogen at 00 to 1000°C to make it embrittle and then pulverized, and the obtained alloy powder is used as a raw material powder for alloying by the mechanical alloying method. The method for producing the alloy powder for rare earth magnets described above. (3) subjecting the rare earth metal or its alloy powder after the hydrogenation reaction to the mechanical alloying treatment without dehydrogenation treatment;
A method for producing alloy powder for rare earth magnets, which comprises subsequently performing dehydrogenation treatment.