JP2837790B2 - Low oxygen rare earth alloy atomized powder and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low oxygen rare earth alloy powder used for electric and magnetic materials in the field of electronics such as permanent magnets and magnetic recording media, and to a method for producing the same.

[0002]

2. Description of the Related Art Alloys containing rare earth elements are used in a wide variety of applications. One of the major uses is an electric material such as a permanent magnet and a magnetic recording medium and a magnetic material.
In these electromagnetic materials, it is necessary to keep the amount of oxygen contained low from the viewpoints of magnetic properties, corrosion resistance, heat resistance and the like. By the way, the conventional production method of the rare earth alloy powder used for these electromagnetic materials has been by mechanical pulverization of an ingot of the rare earth alloy. However, in this method, since the powder may be oxidized in the pulverization process, it is necessary to produce and handle the powder very severely. Further, since the shape of the pulverized powder is irregular and irregular, the fluidity of the powder is poor, and the powder may be oxidized due to ignition or the like during handling of the powder. Therefore, it has been difficult to efficiently and industrially produce low oxygen powder in large quantities. In terms of composition, powder produced by pulverizing an ingot has variations in components due to segregation during casting, making it difficult to obtain a product having a uniform composition.

[0003]

SUMMARY OF THE INVENTION The problem to be solved by the present invention is to provide a rare earth alloy powder having a uniform composition and a low oxygen content without segregation, and a method for efficiently and easily producing the low oxygen rare earth alloy powder. To provide.

[0004]

According to the present invention, an oxygen content in a powder is 500 ppm or less and a particle size distribution of the powder is 5 μm.
gas atomizing method using a spherical low-oxygen rare earth alloy atomized powder having a diameter of not less than m and not more than 500 μm and an alloy base material containing at least 10 atomic% of a rare earth element, and using the molten metal as a spray gas with an inert gas such as Ar or He Thus, a method for producing a low-oxygen-containing rare earth alloy atomized powder in which the amount of residual oxygen in the spray chamber is reduced to 50 ppm or less.

[0005]

Since the rare earth alloy powder of the present invention is obtained by spraying the molten alloy by an atomizing method using an inert gas, the rare earth alloy powder has no segregation as seen in powder obtained by mechanically pulverizing an ingot. 5 and more than 5 μm
Because it is a spherical powder having a particle size distribution of 00 μm or less,
It has good fluidity, is easy to handle, has little danger of explosion, etc., and has an oxygen concentration of 50 in atomized powder.
Since the oxygen content is as low as 0 ppm or less, electromagnetic materials such as permanent magnets and magnetic recording media made of the atomized powder are extremely excellent in magnetic properties, corrosion resistance, heat resistance, and the like.

[0006]

EXAMPLE Nd: 15.0%, B: 8.0% in atomic%,
Fe: A total of 10 kg of a single substance of Nd, B, and Fe and an NdFeB alloy was inserted into an alumina crucible and melted by a vacuum induction melting method so as to have a balance of Fe. On the other hand, Ar gas was previously filled in the atomizing chamber to adjust the oxygen concentration in the atomizing atmosphere to 38 ppm, and then the alloy dissolved by the Ar gas in the atomizing chamber was atomized.

[0007] Table 1 shows the composition and oxygen concentration of the atomized powder produced by this method.

[0008]

[Table 1]

Atomization is performed by changing the oxygen in the atomized atmosphere with the above alloy. FIG. 1 shows the relationship between the oxygen concentration of the powder obtained and the oxygen concentration in the atomized atmosphere.

FIG. 1 shows that if the oxygen concentration in the atomized atmosphere is 50 ppm or less, the oxygen concentration in the obtained atomized powder is 500 ppm or less. However, when the oxygen concentration in the atomized atmosphere exceeds 50 ppm, the oxygen concentration in the obtained atomized powder rapidly increases, and when the oxygen concentration in the atomized atmosphere reaches 60 ppm, the oxygen concentration in the atomized powder becomes nearly 1000 ppm. It turns out that it reaches.

From the above, the oxygen concentration is 500 ppm
In order to produce the following low-oxygen rare earth alloy powder by the atomizing method, it can be seen that the rare earth alloy melt should be gas-atomized in the chamber in which the oxygen concentration in the inert gas atmosphere in the atomizing chamber is 50 ppm or less.

In general, the amount of oxygen in the chamber is determined by the degree of replacement of the air in the chamber with an inert gas at the start of operation. An oxygen content of 50 ppm must achieve an air displacement of 99.75% and, during operation, slight ingress of air from various parts of the system must be prevented. In the past, it was usual not to consider this.

[0013]

As described above, the rare-earth alloy powder containing 10% or more of the rare-earth element in the present invention has a low oxygen content of 500 ppm or less and a uniform composition. When used as a material for magnetic recording media, magnetic materials having excellent magnetic properties, corrosion resistance, heat resistance, and the like can be obtained, and the rare earth alloy powder of the present invention is spherical, so that it is easy to handle and fire. There is less danger of sintering, and it has an excellent effect as compared with the conventional pulverized ingot powder.

Further, the method for producing a rare earth alloy powder of the present invention can produce a low oxygen rare earth alloy powder extremely efficiently and safely as compared with the conventional ingot crushing method.

[Brief description of the drawings]

FIG. 1 is a graph showing a relationship between an oxygen concentration in an atomized atmosphere and an oxygen concentration in an atomized powder.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Shunichiro Nishikawa 3007 1 character Nakajima character in Shima, Himeji City, Hyogo Prefecture Inside Sanyo Special Steel Co., Ltd. (56) References JP 1-2242733 (JP, A) JP 62-130207 (JP, A) JP-A-4-314803 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B22F 9/08 G11B 5/62 H01F 1/053

Claims (2)

(57) [Claims] 1. An oxygen content of a rare earth alloy powder obtained by controlling an oxygen content in an atomized atmosphere to 50 ppm or less in a rare earth alloy powder produced by a gas atomization method of an alloy containing 10 at% or more of a rare earth element. Is 500 ppm or less. 2. A method for producing a rare earth alloy powder in which an alloy containing at least 10 atomic% of a rare earth element is produced by a gas atomization method, wherein the oxygen content in the atomized atmosphere is reduced to 50%.
The oxygen content is controlled to 5 ppm or less.
A method for producing a low-oxygen rare earth alloy gas atomized powder of not more than 00 ppm.