JPS6347344A - Production of low oxygen alloy molding - Google Patents

Abstract

PURPOSE:To produce a sintered molding having a high purity and low oxygen content by melting a metal compd. contg. a metal which can form hydride in a reducing or other atmosphere, cooling and solidifying the separate part contg. oxygen at the lower ratio, hydrogenating the same and sintering the resulted powder. CONSTITUTION:An ingot of Fe and ingot of Tb which are industrially available are used at the time of producing; for example, an iron-terbium alloy sheet as a target for forming a magneto-optical memory medium layer by a sputtering method. The oxide of Fe is reduced by Tb and the oxide of Tb floats on the surface of the melt when these ingots are melted and alloyed in an inert atmosphere of Ar, etc. The floating part is removed and the lower part is cast to a flat sheet shape, then cracks are generated in the casting. The cracked part is cut off to shape the casting. Such sample is put into a hermetic vessel and is brought into contact with high-purity H2 at about 400 deg.C to obtain hydrogenated powder. The powder has the low oxygen content. The sintered body is obtd. by heating the powder in a vacuum sintering furnace after preforming.

Description

[Detailed Description of the Invention] [Object of the Invention] Retired Emperor Dokuri and Dokotan The present invention relates to a method for producing materials that require a low content of impurities such as materials for electronic parts, particularly alloy materials with a low oxygen content. Regarding.

BACKGROUND ART Alloys with low impurity content are required as materials for manufacturing electronic devices, so-called electronic materials. Furthermore, when such materials are used to manufacture electronic devices such as ICs, various storage media, etc., they are often used in the form of sputtering coupons.

A cougette for sputtering is often used as a large flat plate with a diameter of IQ cm, for example, and when the material is an alloy, for example, it is sometimes formed from a melt by a method such as casting. However, in cases where components are likely to segregate, uniform quality cannot be obtained if the product is cooled slowly, and if it is rapidly cooled, internal stress causes cracks and the like, making it impossible to obtain large molded products.

Therefore, in order to obtain homogeneous and large molded products, a method of sintering metal powder is adopted, but when the metal is pulverized, impurities are easily mixed in, and the surface area is large, so it is easily susceptible to oxidation. The drawback is that it is difficult to obtain sintered molded products with high purity and low oxygen content. Particularly in the case of alloys containing easily oxidizable metals as components, it has been difficult to reduce the oxygen content even when sintering is performed in a reducing atmosphere. Moreover,
Mechanically crushed alloys have a wide particle size distribution and are generally coarse, so they have the disadvantage that the sintered molded product has a high porosity and is susceptible to air oxidation even after molding.

Problems to be Solved As mentioned above, when trying to obtain homogeneous and large-sized molded products from alloys for electronic materials that contain metal components that are easily oxidized, the problem is that only products that are easily oxidized and have a high oxygen content can be obtained. There was no other option than to carry out all handling operations in an oxygen-free environment.

Therefore, the present invention seeks to provide a new method that can significantly reduce the oxygen content of large molded articles of such alloys. In other words, it is an object of the present invention to provide a method for producing a low oxygen content molded article of an alloy containing an easily oxidized metal as a component, which is resistant to oxidation even when handled in the atmosphere. It is.

[Structure of the Invention] The object of the present invention as described above is to solve the problem by melting a metal composition containing a metal component capable of forming at least a hydride in a reducing or inert atmosphere. Separating into a portion with high oxygen content and a portion with low oxygen content, cooling and solidifying the low oxygen portion and converting it into powder by hydrogenation,
This is achieved by a method for producing a low-oxygen alloy compact, which is characterized by sintering the obtained powder under vacuum or in an inert atmosphere.

The alloy in the present invention may be essentially of any type, but especially when at least one, two or more of the components contained in the alloy are metals that are easily oxidized. You can get excellent results. Further, in the case of an alloy consisting only of metals that are not so easily oxidized, the improvement effect is not so remarkable compared to alloys containing metals that are easily oxidized, but it is still effective in reducing the oxygen content.

Such an alloy must contain at least one of its components a metal capable of forming a hydride. Metals that can form hydrides include 2A of the periodic table.
, 3A, 4A, 5A, 6A, etc., particularly rare earth metals, titanium, zirconium, etc., are preferably used, but such metals may be contained as essential components of the alloy. , or may be contained as an optional component, or as a component that is not a necessary component but is harmless even if added.

Such a metal compound containing a metal capable of forming a hydride may be in the form of powder, granules, or ingot, but after being mixed, it is placed in a reducing or inert atmosphere, such as a hydrogen atmosphere or an argon atmosphere. Alternatively, it is once melted under reduced pressure or vacuum in such an atmosphere, and the part containing a large amount of metal oxide is floated to separate the lower layer containing less oxide, which is then cooled and solidified. do.

During this cooling assimilation, it is necessary to solidify in a reducing or inert atmosphere similar to that during melting.

The solidified alloy is hydrogenated by contacting with hydrogen subsequent to solidification, or at a suitable time after solidification. The hydrogenation process can be carried out under conditions suitable for each type of alloy. The alloy expands by absorbing high-purity hydrogen and hydrogenating, and fractures due to internal stress. As long as the amount of metal that can form hydrides is not too small, crushing will proceed along with hydrogenation, and all will become powder. The hydrogenated alloy thus powdered can be safely handled without being oxidized under normal indoor environments.

The hydrogenated alloy powder obtained as described above is either pre-formed into a desired shape by pressing or placed in a metal molding container as it is, heated under vacuum or in an inert atmosphere, Sintering is performed while hydrogen is released. By simultaneously applying pressure during heating and sintering, a molded product with a smaller porosity and a more precise shape can be obtained.

Production-■ According to the method of the present invention, the obtained molded product has high purity and precise shape, and has little internal distortion, so it is possible to easily obtain a large-sized molded product. Since the porosity is small, oxidation progresses slowly even when handled in air, and a molded product with extremely low oxygen content and high purity can be obtained.

EXAMPLE An example of manufacturing an iron-terbium alloy plate as a target for forming a magneto-optical storage medium layer by sputtering will be described below.

Industrially available high-purity iron ingot (sample A)
and terbium ingot (sample B) are 20-30 ppm and 6 ppm by weight, respectively.
00 to 700 ppm, and when these are melted and alloyed in an inert atmosphere such as argon (molar ratio, sample A/sample B = 8/2), iron oxide is converted to terbium by terbium. Upon reduction, terbium oxide floats to the surface of the melt. Therefore, when the floating part was removed and the lower layer part was cast into a flat plate (150 mm X L50 Tsuru X20111), cracks occurred. Then, when I shaved off the crack and shaped it, it was 3cm x 3cm x 2cm.
Ten plate-like bodies of about I11 were obtained. The oxygen content of the cast product (sample C) at this time was 400 to 480 pp by weight.
It was m.

On the other hand, industrially available high-purity iron powder sample D)
and terbium powder (sample E) are 0.1% and 0.6%-2% by weight, respectively, and the particle sizes are 10-100 μm and 40-1 μm, respectively.
It is 20 IJm. Blend these (in molar ratio, sample D/
The oxygen content of the powder formulation (sample F) obtained by sample E=8/2) was 0.5-1% by weight.

In addition, when sample C was mechanically pulverized in an argon atmosphere, a powder of 5 to 70 μm (sample G) was obtained, but when it came into contact with oxygen in the air, oxidation proceeded immediately, and the oxygen content decreased by weight. reached 0.4-0.6%. This value is slightly lower than that of Sample F, which was obtained by blending Sample E with the aforementioned Sample Sample.

Separately, when Sample C (including the aforementioned cast product and its fragments) was placed in a sealed container and brought into contact with high-purity hydrogen with a dew point of 185°C at approximately 400°C, the particle size was 20 to 40 μm.
A hydrogenated powder (sample H) of about m was obtained. Sample H had an oxygen content of 650 to 900 ppm by weight and was stable even in contact with air.

Next, sample F of each powder obtained as described above
(powder mixture product), sample G (mechanically crushed product), and sample H
(Hydrogenated powder) is pre-pressed and each has a diameter of 125 mm.
It was formed into a disk shape with a thickness of Sample K
) was obtained.

Separately, a hot press at 1500 kg/crA was also used during sintering to obtain corresponding sintered bodies (sample sample, sample M, and sample N).

The results obtained by measuring the oxygen content and porosity of these sintered bodies are shown in Table 1 together with the oxygen content of the powder used as the raw material.

The results show that according to the method of the present invention, an alloy compact with a low oxygen content, which is particularly dense and resistant to oxidation, can be obtained, and the permissible oxygen content as a target for a magneto-optical storage medium layer is 0. It can be seen that a molded article satisfying the condition of 2% or less can be obtained.

Table 1 Sample Oxygen content% Porosity% Note F
0.05-1 Powder compound G
004~0.6 Mechanically crushed product HO
,06-0,09 Hydrogenated powder I
1 to 2 Sample F used J
O15~1 25 Sample G used K
O,06~0.18 13 Sample H used L
1-2 Sample F used M
O, 5~1 Sample G used N
O, 15 to 0.20 2 Sample H Usage Example-2 An example of manufacturing a titanium-silicon 2 alloy plate as a target used to form an electrode part of a VLSI by sputtering will be described.

Industrially available high-purity spongy titanium (sample ○
) and a silicon ingot (sample P) were melted in an inert atmosphere such as argon to obtain an alloy (sample Q) with a molar ratio of 1:2, but this was brittle and difficult to manufacture into a large plate. I couldn't do it.

The oxygen content was 300-400 ppm by weight.

When sample Q was mechanically pulverized into powder with a diameter of 60 μm or less (sample R), oxidation progressed on contact with air, and the oxygen content increased from 600 ppm to 0.25% by weight.

In addition, by placing sample Q in an airtight container and contacting it with high-purity hydrogen with a dew point of 185°C at approximately 800°C, a diameter of 40μ
A hydrogenated powder (sample S) having a particle size of 1.0 m or less was obtained. Sample S had an oxygen content of about 700 ppm by weight and was stable even in contact with air.

Next, sample R (mechanically pulverized product) and sample S (hydrogenated powder) of the powder obtained as described above were pre-pressed to give a diameter of 12 mm.
The sintered bodies (sample T and sample U, respectively) were formed into a disk shape of 5 mm x 8 nm thick, then placed in a vacuum sintering furnace, maintained at a vacuum level of 10-6 Torr, and heated to 1300°C. Obtained.

The oxygen content and porosity of these sintered bodies are shown in Table 2 together with the oxygen content of the powder used as the raw material.

These results show that the method of the present invention yields a dense alloy compact with a low oxygen content, which satisfactorily satisfies the requirement of an allowable oxygen content of 0.1% or less as a target for forming the electrode part of a VLSI. It can be seen that a satisfactory product can be manufactured easily.

Table 2 Sample Oxygen content % Porosity % Note RO, 0
7～0.2 Mechanically crushed product S
O,05~0.06 Hydrogenated powder T
O, 15~0.2 Sample R used U O, 07~0.08 7
Use of Sample S [Effects of the Invention] According to the method for producing a low-oxygen alloy molded article of the present invention, when producing a large molded article of an alloy containing easily oxidized metal components, hydrogenated powder that is resistant to oxidation is Since the raw material is used in the form of a body, a product with a low oxygen content can be easily obtained without special care in handling. Since the molded product thus obtained has a high density, it is resistant to oxidation even when handled in the atmosphere. Furthermore, since sintering proceeds simultaneously with dehydrogenation of the hydrogenated powder, the sintering temperature is not only low, but also has the advantage that internal distortion is small and larger molded products can be manufactured more easily.

Furthermore, in addition to the above-mentioned applications, the method of the present invention can also be suitably used to produce compacts of alloys containing metals capable of forming hydrides, such as superconducting materials and magnetic materials containing rare earth metals. It has the advantage of being able to

Claims (1)

[Claims] A metal compound containing at least a metal component capable of forming a hydride is separated into an oxygen-rich portion and an oxygen-poor portion by melting it in a reducing or inert atmosphere, and A method for producing a low-oxygen alloy molded body, which is characterized by cooling and solidifying the remaining part, converting it into powder by hydrogenation, and sintering the obtained powder under vacuum or in an inert atmosphere. .