JPH07316681A - Production of metallic material or alloy material, refining agent and metallic material or alloy material excellent in corrosion resistance - Google Patents

Abstract

PURPOSE:To obtain a metallic material reduced in oxygen concn. at the time of melting raw metallic material such as Zr by an electron beam, etc., to produce the metallic material by bringing the hydride of the metal into contact with the molten metal. CONSTITUTION:The raw material consisting of one kind of metal selected from Ti, Zr, Hf, Nb, Ta, W and Mo or the alloy consisting essentially of the metal and alloy element is melted by electron beam, plasma or vacuum arc to produce the metallic material or alloy material. At this time, the molten metal or alloy is brought into contact with the hydride of the metal (TiH2, ZrH2, NbH, NbH2, MoHx, TaHx, WHx, etc.) or the hydride of the alloy element to reduce the oxygen concn. In this case, about 1 to 10 equivalents of the hydride, expressed in terms of hydrogen, to the oxygen in the raw material is added. Consequently, a high-purity refined metallic material contg. <=about 100ppm oxygen is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a high-purity metallic material or alloy material, and more specifically, metallic materials such as titanium, zirconium, hafnium, niobium, tantalum, tungsten, molybdenum, etc. Alternatively, the present invention relates to a method for producing an alloy material containing any one of these metals as a main component and one or more other metals or various alloy elements such as vanadium and aluminum. Further, the present invention relates to a purifying agent for a crude metal (alloy) such as titanium, zirconium, hafnium, niobium, tantalum, tungsten and molybdenum, and a refining agent for further refining a metal (alloy) once the crude metal (alloy) is refined. . In addition, the invention relates to metal and alloy materials having improved corrosion resistance by reducing impurities to extremely low levels.

High-purity zirconium or a zirconium alloy can be obtained by using sponge zirconium or a sponge zirconium alloy as a raw material and purifying the sponge zirconium or sponge zirconium alloy by an iodide decomposition method utilizing the reactions of the following formulas (1) and (2). Zr + 2I2 = ZrI4 (1) ZrI4 = Zr + 2I2 (2) Equation (1) occurs in the low temperature range of 200 to 500 ° C to generate iodide, and then Equation (2) Occurring in a high temperature range of 1100 to 1500 ° C., iodide is decomposed and high-purity Zr is deposited and purified. In addition to zirconium (alloy), titanium, hafnium (alloy) and the like are highly purified by the iodide refining method. However, in the iodide refining method and the molten salt electrolysis method, 4N
High-purity metals and alloys of about 6 N can be obtained, but since the production amount per time is small, it is necessary to go through a melting step to make them into a lump product.

It is also known to produce high-purity titanium by a molten salt electrolysis method or a combination of a molten salt electrolysis method and an electron beam melting method (Journal of the Japan Institute of Metals "Materia").
January 1994, p. 54). Further, regarding zirconium, zirconium is used for the anode and the cathode,
It is also known to purify high-purity zirconium by using, for example, a chloride-fluoride mixed bath of NaCl-K2 ZrF6 system as an electrolytic bath. Furthermore, as for tantalum, Ta of the vacuum arc melting electrode or by electron beam melting is used.
It is known that the oxygen concentration becomes extremely low by adding C therein, but it is pointed out that C remains after the dissolution by the method of adding C.

It is said that the oxygen concentration of molybdenum decreases to several ppm by repeating vacuum arc melting.

Metals such as titanium, zirconium, and niobium and their alloys have extremely high activity with respect to oxygen, nitrogen, etc., so that in order to produce a high-purity material by the melting method, the melting energy density is high and the impurity element is evaporated. Electron beam melting, plasma melting, vacuum arc melting, etc. are used to achieve easy conditions. According to these dissolution methods, M
Impurity elements such as g, Na, Cl, and H2 are surely reduced, and a lump material like an ingot can be manufactured. Therefore, titanium, zirconium, etc., which are used as structural materials for nuclear reactor materials, marine materials, chemical plants, etc., are molded into parts through these melting methods.

[0006] In particular, regarding the lining material for fuel cladding tubes for boiling water reactors, it is currently used as a material satisfying the good corrosion resistance required for highly oxidizing solutions such as nitric acid in the reprocessing process. The composition of a typical zirconium alloy is shown below.

[0007]

[Table 1] Impurities (ppm) Hf Fe Cr Ni Cu ONCH <50000 <2000 <2000 1000 100 1800 100 500 50

It has been conventionally known that Ta is deoxidized by Ca among the various metals mentioned above. However, it is necessary to remove CaO generated when deoxidizing with Ca with acid. Since other metals have a certain refining effect by electron beam melting or the like, it has not been industrially carried out to intentionally use a refining agent to reduce impurities. Further, the refining agent needs to be an element having extremely high oxygen activity such as Ca.
Removal of reaction products such as O out of the system cannot be expected by electron beam melting, plasma melting and vacuum arc melting methods.

[0009]

In the electron beam melting, plasma melting and vacuum melting methods, metals such as Ti, Zr and Hf have a high affinity with oxygen, so that oxygen as an impurity is preferentially removed and purified. I can't. Moreover, since the difference in vapor pressure between the metal oxide such as Zr lower oxide and the metal Zr is small, the deoxidation reaction due to the evaporation of the oxide does not occur. Therefore, if the oxygen concentration in the raw material becomes extremely low, deoxidation during electron beam melting cannot be expected, so there has been a demand for the development of a more effective deoxidation technique.

W, Nb and Ta are produced by electron beam melting,
Further, although Mo is a metal capable of removing and refining oxygen by vacuum arc melting, it is expected to reduce the oxygen concentration more efficiently.

Therefore, Ti, Zr, Hf, Nb, T
When a, W or Mo (hereinafter referred to as "active metal") or an alloy containing this as a main component is subjected to electron beam melting, plasma melting and vacuum melting, if oxygen can be effectively removed, the amount of oxygen in the raw material It is possible to achieve deoxidation during the dissolution of highly active metals, and as the raw material, in addition to the molten salt electrolytic material, scrap raw material containing oxide scale or powdery raw material that easily oxidizes the surface can be preferably used. become.

Next, Fe, Ni, Cr, S in the active metal
Impurities such as n have a small vapor pressure difference from active metals such as Ti and Zr, and cannot be effectively removed by electron beam melting, plasma melting and vacuum melting methods. That is, when these impurities are considerably reduced by molten salt electrolysis, reduction by the electron beam melting method or the like cannot be expected. The inventors of the present invention have conducted extensive studies to reduce these impurities by an electron beam melting method or the like, and remove the above impurities when electron beam melting, plasma melting, or vacuum melting an active metal or an alloy containing the active metal as a main component. We succeeded in providing a method that can be effectively removed. According to this method, high-purity purification can be performed using a raw material from which the above-mentioned impurities have been removed to some extent by the molten salt electrolysis method, or a raw material which has not undergone molten salt electrolysis.

In the conventional electron beam melting method and the like, oxygen and impurities such as Fe, Ni, Cr, and Sn could not be reduced at the same time for the above-mentioned reasons. It is intended to provide a method capable of effectively removing the above-mentioned impurities including oxygen when the above alloy is subjected to electron beam melting, plasma melting and vacuum melting.

Conventionally, when a structural material made of an active metal or its alloy is used in a corrosive medium in which stress corrosion is likely to occur, sensitization of stress corrosion susceptibility occurs due to high impurity level, especially oxygen level, There was a concern that delayed destruction would occur. For these structural materials, ingots are suitable for the above reasons, but it has been impossible to produce highly purified materials by the conventional melting method. The present invention is to produce a raw material ingot of an active metal or alloy structural material used in a medium in which stress corrosion is likely to occur by only electron beam melting, plasma melting or vacuum arc melting. According to this method, sponge titanium, zirconium, tantalum powder, molybdenum powder, or scrap material thereof, which are industrially common raw materials, are used as raw materials to dissolve O2, Mg, Na, Cl, H2, N2 during melting.
It becomes possible to remove impurities such as.

In the conventional electron beam melting, plasma melting and vacuum arc melting, it has been found that an unexpected phenomenon occurs in which a small amount of oxygen present in the melting atmosphere reacts with the active metal and the oxygen concentration increases after melting. That is, since the melting conditions of these methods are such that a large amount of energy is efficiently given to the material to be melted in a high vacuum atmosphere, oxidation is generally difficult to occur, but the oxygen concentration is set to 1 by the molten salt electrolysis method.
It was confirmed that significant oxidation occurs when using a raw material lowered to the 00 ppm range. The present invention has an oxygen concentration of 50.
When the active metal raw material regulated to 00 ppm or less is melted by a method such as electron beam melting, plasma melting, or vacuum arc melting, the oxygen concentration in the refined metal is reduced and the oxygen concentration is increased by the residual oxygen in the melting atmosphere. To provide a method of preventing According to this method, for example, an active metal having an oxygen concentration of 5000 ppm or less is obtained by a molten salt electrolysis method, and the active metal is purified by the above-mentioned dissolution method to obtain a high-purity purification method having an oxygen concentration of 100 ppm or less.

Further, the active metal refining agent (a) has a high refining effect; (b) it is not necessary to remove the reaction product by a separate process such as pickling; (c) the mainstream of active metal dissolution at present. When it can be used in electron beam melting, plasma melting, and vacuum arc melting, which is also preferable in other melting methods, it can contribute to the production of high-purity active metal.

[0017]

[Means for Solving the Problems] The inventors of the present invention diligently conducted a number of experiments from various viewpoints regarding a dissolution means that can achieve the above-mentioned object and can be carried out inexpensively and stably on an industrial scale. As a result of repeated research, the following inventions have been completed. The first method of the present invention is electron beam melting,
By plasma melting or vacuum arc melting, Ti, Zr,
A method for producing a metal material or an alloy material by melting a raw material made of a metal selected from the group consisting of Hf, Nb, Ta, W or Mo or an alloy containing the metal as a main component and containing an alloy element, The method for producing a metal material or an alloy material, which comprises contacting the hydride or the hydride of the alloy element with a molten metal of the metal or alloy.

In the second method of the present invention, the oxygen concentration is 500.
A metal material or an alloy material is prepared by melting a raw material made of a metal selected from the group consisting of Ti, Zr, Hf, Nb, Ta, W, or Mo of 0 ppm or less or an alloy containing the metal as a main component and containing an alloying element. A method for producing a metal material or an alloy material, which comprises contacting a hydride of the metal or a hydride of the alloy element with a molten metal of the metal or alloy.

The first refining agent of the present invention is Ti, Zr, H.
A refining agent for removing impurities of one kind of metal selected from the group consisting of f, Nb, Ta, W and Mo, or an alloy containing this metal as a main component and containing an alloying element.
A refining agent for a metal material or an alloy material, characterized in that the refining agent comprises a metal hydride of one kind, wherein the second refining agent is Ti, Zr, Hf, N other than the one metal.
A refining agent for an alloy material, comprising one or more metals selected from the group consisting of b, Ta, W and Mo, wherein the hydride is a hydride of the one metal. And the third refining agent is Ti, Zr, Hf, Nb, T
a, W and Mo as a main component of one kind of metal selected from the group consisting of, containing one or more kinds of alloying elements selected from the group consisting of Ti, Zr, Hf, Mo, Ta, W Is a refining agent for removing impurities from the alloy, and is a refining agent for an alloy material, characterized by comprising a hydride of the alloy element.

The structure of the present invention will be described below. In the present invention, the hydride is brought into contact with the molten metal as a refining agent, but it is necessary to efficiently remove the H2 O generated by the reaction with O2 outside the system. In the electron beam melting, plasma melting, or vacuum arc melting methods, the refining effect due to the vapor pressure difference between the metal to be melted such as Ti and the impurity element is large, so it is expected that evaporation of H2 O will enhance the refining effect of the impurities. The dissolution method of the present invention described above is, for example, 30 to 1000 mm in diameter,
It is suitable for producing large ingots having a length of 5000 mm or less, and can be processed into various structural materials by processing. Further, a material for a high-purity sputtering target for manufacturing a semiconductor device can also be manufactured by the electron beam melting method.

In the second method, the concentration of the oxygen component of the raw material is regulated to 5000 ppm or less because the decomposed H2 gas remains in the vacuum exhaust system and there is a risk of explosion.

In the present invention, impurities are purified by bringing a hydride into contact with a molten metal or metal alloy, and the hydride is used as a refining agent. This is the greatest feature of the present invention. The hydride referred to in the present invention is an additive metal element (including an active metal) of an active metal or alloy material.
And the compound. Further, the hydride is formed as a compound with the component metal of the material to be dissolved so as to prevent contamination by the metal remaining in the material to be dissolved after the hydride is dissolved. Further, from the viewpoint of safety and stability of operation, hydrides whose decomposition temperature or evaporation temperature are too low or which are highly reactive are not preferable, so active metal hydrides having a relatively high dissociation temperature, particularly TiH
2, ZrH2, NbH, NbH2, MoHx, TaHx
, WHx, etc. are preferably used.

The method of bringing the hydride into contact with the molten metal and the method of using the first to third refining agents in the first and second methods are not particularly limited in principle, but the molten metal can be accessed by the melting method. Is determined in several modes,
Among these embodiments, a method is selected in which the entire amount of the molten metal can come into contact with the hydride. First, in the electron beam melting method, a method of adding a hydride to a molten metal in a cold hearth, a water-cooled copper mold or the like has a great effect and is convenient for continuous casting after melting. Alternatively, a method of adding a hydride into the electrode can be adopted. Next, in vacuum arc melting, it is preferable to add a hydride to the raw material which is the electrode by an appropriate method. The addition method may be a method in which a lump such as titanium sponge and a hydride powder are mixed, and then the lump and the powder are combined by pressure molding to form an electrode shape. In the plasma arc melting method, a method of adding a hydride to a molten metal in a mold to be melted is effective. Further, when the molten metal is once poured into the ladle and then the ingot is cast as in the vacuum arc melting method, a hydride can be added to the ladle. As a method of addition, various methods such as pouring or spraying on the surface of the molten metal; spraying below the surface of the molten metal with a water-cooled copper pipe or the like can be adopted.

In the present invention, the hydride removes impurities contained in the raw material active metal and hard to be removed by evaporation. Oxygen in these impurities bonds with hydrogen to be deoxidized. In addition, Fe, Ni, Cr, S, which were conventionally considered to have no refining effect due to vapor pressure difference in electron beam melting, etc.
n and the like are also removed. The surprising result was that these elements were removed in the presence of hydride, although they were lower than the removal rate of oxygen in the raw material coexisting with oxygen.

Therefore, the types of impurities to be removed depend on the types of raw materials and manufacturing history, and oxygen is mainly contained in a material having a large amount of oxygen, and other metals such as Fe and Ni are contained in a metal such as Mo and Ta whose oxygen is easily reduced. Impurities will be removed by the hydride. When mainly removing oxygen, it is preferable to add 1 equivalent to 10 equivalents, preferably 2 to 5 equivalents of hydride in terms of hydrogen of the hydride with respect to oxygen in the raw material.

The raw material form of the active metal to be dissolved by the method of the present invention is various such as sponge metal such as titanium sponge, zirconium, molten salt electrolytic metal, ingot obtained by high-frequency melting or vacuum melting sponge metal, scrap after product processing, and the like. The form can be used. Sponge metal is preferable from the viewpoint of cost reduction, while molten salt electrolytic metal is preferable from the viewpoint of high-purity purification in which impurities are extremely reduced.

Since hydrides generally have a low specific gravity, when they are used by adding them to a molten metal, if they are powdery, they float on the surface of the molten metal and cannot sufficiently contact with the molten metal. Therefore, it is preferable to contact the molten metal in the form of a lump or block having a size of 20 mm or less. More preferable size is 1 to 15
mm. On the other hand, when used as a mixture with a raw material, the hydride is preferably in powder form. Also, when the hydride is used by injecting it into the molten metal with a water-cooled copper pipe or the like, the powder form is preferable.

The zirconium-based material provided by the present invention has an oxygen content of 100 ppm or less, preferably 50 ppm.
ppm or less, total amount of nitrogen, carbon and hydrogen is 30 ppm
A zirconium-based material having excellent corrosion resistance, which is preferably 10 ppm or less, iron, chromium, and nickel are 50 ppm or less, preferably 20 ppm or less, hafnium is 500 ppm or less, and the balance is substantially zirconium. And one or two selected from the group consisting of Sn, Nb, and Hf as alloy elements
A zirconium-based material having excellent corrosion resistance, which is characterized by containing 5% or less of one or more metals.

This material has an extremely low level of impurities such as O 2 component, and a material having better corrosion resistance than the conventional material in a corrosion resistance test in boiling nitric acid was obtained. Suitable as a lining. Further, the above-mentioned materials are obtained by dissolving sponge zirconium having a normal purity as a raw material.

The conditions for electron beam melting, plasma melting and vacuum arc melting, that is, the degree of vacuum, output of electron beam, plasma, melting temperature, etc. may be the same as usual. An apparatus for carrying out the method of the present invention will be described below with reference to FIGS.

FIG. 1 illustrates one embodiment of an apparatus for practicing the present invention by the electron beam cold hearth remelt method. In the figure, 1 is a water-cooled copper mold, 2 is a water-cooled cold hearth, 3 is a raw material electrode, 4 is an electron gun, 5 is an electron beam,
6 is an ingot, 7 is a hydride addition hopper, and 8 is a molten metal.

As shown in FIG. 1, a water-cooled cold hearth 2 made of copper is installed in front of a water-cooled copper mold 1 installed in a melt chamber of an electron beam melting facility, and a raw material electrode 3 is supplied from an electron gun 4 to an electron. The raw material melt melted by the beam 5 is temporarily held in the cold hearth 2 and then overflowed. The raw metal melt is cast into the water-cooled copper mold 1 and continuously solidified while being pulled out as an ingot 6 from below. The hydride is stored as a mass in the hydride addition hopper 7.
Deploy. The output of the electron beam 5 is about 30 to 2000 kW, and the furnace pressure is about 10 −2 to 10 −6 mbar.

In FIGS. 2 and 3, a vibrator 11 is fixed to a hydride addition hopper 7 having a capacity of about 10 liters, in which a hydride mass 10 is placed, and a tank 11 of the hopper is placed above a water-cooled hearth 12. The pipe portion 7a extending up to is a water-cooled copper jacket. The molten metal added with the hydride is cast into the water-cooled copper mold 1 through the injection hole of the water-cooled hearth 12. The vibrator 11 is vibrated, for example, at a frequency of 10 to 500 Hz, and the hydride is added so as to be 1 to 10 equivalents with respect to the oxygen concentration of the raw material electrode 3 analyzed in advance.

[0034]

Function: Zirconium hydride mass is melted into Zr melt (temperature = Zr
(Melting point + about 100 ° C.) and visually observing the surface of the molten metal, it is recognized that the zirconium hydride mass is immediately fused with the molten metal. At this time, it is considered that deoxidation proceeds due to the following reaction. ZrH2 + 1 / 2O2 = Zr + H2 O (3) In addition, active hydrogen dissociated from zirconium hydride undergoes an adsorption reaction with metal clusters of impurity components and is a metastable compound with a constant component ratio. It is believed that a so-called non-stoichiometric compound is produced, which is removed by evaporation. It is considered that impurities are removed from active metals other than Zr and hydrides by the same phenomenon.

One of the refining reaction products is the metal to be melted or its alloying element, so it is integrated with the ingot, and the other refining reaction product, H 2 O, easily evaporates in the vacuum of the melting atmosphere. . Therefore, it can be said that the purifying agent of the present invention has no secondary effect as compared with the conventional purifying agent such as Ca and is ideal. Therefore, even with zirconium having an oxygen concentration on the order of 100 ppm, which easily causes reoxidation due to the melting atmosphere, deoxidation up to the level of 10 ppm can be achieved without concern about the residual refining agent in the ingot.
Furthermore, the refining agent of the present invention is an epoch-making element in which the elements to be purified and removed are not limited to oxygen like Ca but also iron, nickel, chromium and the like.

100 to 1000 ppm for zirconium
Oxygen of the platform exists in a solid solution state and induces stress corrosion in acid. The corrosion resistance of zirconium can be enhanced by reducing the oxygen having such adverse effects. Hereinafter, the present invention will be described with reference to examples.

[0037]

EXAMPLE A high-purity zirconium ingot having a diameter of 85 mm and a length of 150 mm was melted by an electron beam melting method and continuously cast using the apparatus shown in FIG. The raw material electrode is a molten salt electrolyzed sponge Zr, and the molten metal temperature in the cold hearth 2 and the water-cooled copper mold 1 is 1950 ° C.
The output of the electron beam 5 was 200 kW, and the pressure in the melt chamber containing the entire apparatus of FIG. 1 was 10-4 mbar. Zirconium hydride (bulk specific gravity 1.25 g / cm3)
Has an average size of 3 mm, and 1 equivalent of hydrogen was added to the oxygen concentration of the raw material. The test result is ZrH
2 is shown in Table 2 together with a comparative example in which no additive is added.

[0038]

[Table 2] Impurities (ppm) Hf Fe Cr Ni ONCH Raw material 330 100 100 100 180 30 40 2 ZrH2 additive-free 330 100 100 100 250 3 32 1 ZrH2 additive 330 <50 <50 <50 50 3 <20 <1

[0039]

Industrial Applicability As described above, according to the method and the purifying agent of the present invention, active metals and alloys containing less impurities such as oxygen can be stably and inexpensively produced, which is extremely industrially advantageous. Has a beneficial effect. Further, since the zirconium-based material of the present invention has excellent corrosion resistance, it exhibits excellent performance as a reactor material, marine material, chemical plant, etc., and excellent performance can be obtained without using expensive additive elements. Therefore, it is also advantageous in saving resources.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of an apparatus for carrying out the present invention by an electron beam cold hearth remelt method.

FIG. 2 is a plan view showing an apparatus for adding a hydride by a vibration method.

FIG. 3 is a side view and a partial cross-sectional view of FIG.

[Explanation of symbols]

 1 water-cooled copper mold 2 water-cooled cold hearth 3 raw material electrode 4 electron gun 5 electron beam 6 ingot 7 hydride addition hopper 8 molten metal

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[Procedure amendment]

[Submission date] June 7, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0002

[Correction method] Change

[Correction content]

High-purity zirconium or a zirconium alloy can be obtained by using sponge zirconium or a sponge zirconium alloy as a raw material and purifying the sponge zirconium or sponge zirconium alloy by an iodide decomposition method utilizing the reactions of the following formulas (1) and (2). Zr + 2I ₂ = ZrI ₄ (1) ZrI ₄ = Zr + 2I ₂ (2) Formula (1) occurs in a low temperature range of 200 to 500 ° C. to generate iodide, and then ( 2) occurs in a high temperature range of 1100 to 1500 ° C., iodide is decomposed, and high-purity Zr is deposited and purified. In addition to zirconium (alloy), titanium, hafnium (alloy) and the like are highly purified by the iodide refining method. However, in the iodide refining method and the molten salt electrolysis method, 4N
High-purity metals and alloys of about 6 N can be obtained, but since the production amount per time is small, it is necessary to go through a melting step to make them into a lump product.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0003

[Correction method] Change

[Correction content]

It is also known to produce high-purity titanium by a molten salt electrolysis method or a combination of a molten salt electrolysis method and an electron beam melting method (Journal of the Japan Institute of Metals "Materia").
January 1994, p. 54). Further, regarding zirconium, zirconium is used for the anode and the cathode,
Chloride to the electrolytic bath for instance NaCl-K ₂ ZrF ₆ system - using a fluoride bath mixture, it is also known to purify high purity zirconium. Furthermore, as for tantalum, Ta of the vacuum arc melting electrode or by electron beam melting is used.
It is known that the oxygen concentration becomes extremely low by adding C therein, but it is pointed out that C remains after the dissolution by the method of adding C.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0005

[Correction method] Change

[Correction content]

Metals such as titanium, zirconium, and niobium and their alloys have extremely high activity with respect to oxygen, nitrogen, etc., so that in order to produce a high-purity material by the melting method, the melting energy density is high and the impurity element is evaporated. Electron beam melting, plasma melting, vacuum arc melting, etc. are used to achieve easy conditions. According to these dissolution methods, M
Impurity elements such as g, Na, Cl, and H ₂ are surely reduced, and a bulk material can be manufactured like an ingot. Therefore, titanium, zirconium, etc., which are used as structural materials for nuclear reactor materials, marine materials, chemical plants, etc., are molded into parts through these melting methods.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction content]

Conventionally, when a structural material made of an active metal or its alloy is used in a corrosive medium in which stress corrosion is likely to occur, sensitization of stress corrosion susceptibility occurs due to high impurity level, especially oxygen level, There was a concern that delayed destruction would occur. For these structural materials, ingots are suitable for the above reasons, but it has been impossible to produce highly purified materials by the conventional melting method. The present invention is to produce a raw material ingot of an active metal or alloy structural material used in a medium in which stress corrosion is likely to occur by only electron beam melting, plasma melting or vacuum arc melting. According to this method, sponge titanium, zirconium, tantalum powder, molybdenum powder, or scrap material thereof, which are industrially common raw materials, are used as raw materials to dissolve O ₂ , Mg, Na, Cl, H ₂ , N ₂
It becomes possible to remove impurities such as.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0020

[Correction method] Change

[Correction content]

The structure of the present invention will be described below. In the present invention, the hydride is brought into contact with the molten metal as a refining agent, but it is necessary to efficiently remove the H ₂ O generated by the reaction with O ₂ out of the system. In the electron beam melting, plasma melting, or vacuum arc melting methods, the refining effect due to the vapor pressure difference between the metal to be melted such as Ti and the impurity element is large, so it is expected that the evaporation of H ₂ O will enhance the refining effect of the impurities. The dissolution method of the present invention described above is, for example, 30 to 1000 mm in diameter,
It is suitable for producing large ingots having a length of 5000 mm or less, and can be processed into various structural materials by processing. Further, a material for a high-purity sputtering target for manufacturing a semiconductor device can also be manufactured by the electron beam melting method.

[Procedure correction 6]

[Document name to be amended] Statement

[Name of item to be corrected] 0022

[Correction method] Change

[Correction content]

In the present invention, impurities are purified by bringing a hydride into contact with a molten metal or metal alloy, and the hydride is used as a refining agent. This is the greatest feature of the present invention. The hydride referred to in the present invention is an additive metal element (including an active metal) of an active metal or alloy material.
And the compound. Further, the hydride is formed as a compound with the component metal of the material to be dissolved so as to prevent contamination by the metal remaining in the material to be dissolved after the hydride is dissolved. Further, from the viewpoint of safety and stability of operation, a hydride having a decomposition temperature or an evaporation temperature that is too low or a highly reactive one is not preferable, and therefore an active metal hydride having a relatively high dissociation temperature, particularly Ti
H ₂ , ZrH ₂ , NbH, NbH ₂ , MoH _x , TaH _x
, WH _{x and the} like are preferably used.

[Procedure Amendment 7]

[Document name to be amended] Statement

[Name of item to be corrected] 0029

[Correction method] Change

[Correction content]

This material has an extremely low level of impurities such as O ₂ component, and a material having better corrosion resistance than a conventional material in a corrosion resistance test in boiling nitric acid can be obtained, and a fuel cladding tube for a boiling water reactor is obtained. It is suitable as a lining. Further, the above-mentioned materials are obtained by dissolving sponge zirconium having a normal purity as a raw material.

[Procedure Amendment 8]

[Document name to be amended] Statement

[Name of item to be corrected] 0032

[Correction method] Change

[Correction content]

As shown in FIG. 1, a water-cooled cold hearth 2 made of copper is installed in front of a water-cooled copper mold 1 installed in a melt chamber of an electron beam melting facility, and a raw material electrode 3 is supplied from an electron gun 4 to an electron. The raw material melt melted by the beam 5 is temporarily held in the cold hearth 2 and then overflowed. The raw metal melt is cast into the water-cooled copper mold 1 and continuously solidified while being pulled out as an ingot 6 from below. The hydride is stored as a mass in the hydride addition hopper 7.
Deploy. The output of the electron beam 5 is about 30 to 2000 kw, and the furnace pressure is about 10 ^-2 to 10 ^-6 mbar.

[Procedure Amendment 9]

[Document name to be amended] Statement

[Correction target item name] 0034

[Correction method] Change

[Correction content]

[0034]

Function: Zirconium hydride mass is melted into Zr melt (temperature = Zr
(Melting point + about 100 ° C.) and visually observing the surface of the molten metal, it is recognized that the zirconium hydride mass is immediately fused with the molten metal. At this time, it is considered that deoxidation proceeds due to the following reaction. ZrH ₂ + 1 / 2O ₂ = Zr + H ₂ O (3) Further, active hydrogen dissociated from zirconium hydride undergoes an adsorption reaction with a metal cluster of an impurity component and is a metastable compound, It is considered that a so-called non-stoichiometric compound having a non-constant ratio is formed, and this is removed by evaporation. It is considered that impurities are removed from active metals other than Zr and hydrides by the same phenomenon.

[Procedure Amendment 10]

[Document name to be amended] Statement

[Correction target item name] 0035

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Since one of the purified reaction products is the metal to be melted or its alloy element, it is integrated with the ingot, and the other purified reaction product, H ₂ O, easily evaporates in the vacuum of the melting atmosphere. To do. Therefore, it can be said that the purifying agent of the present invention has no secondary effect as compared with the conventional purifying agent such as Ca and is ideal. Therefore, even with zirconium having an oxygen concentration on the order of 100 ppm, which easily causes reoxidation due to the melting atmosphere, deoxidation up to the level of 10 ppm can be achieved without concern about the residual refining agent in the ingot.
Furthermore, the refining agent of the present invention is an epoch-making element in which the elements to be purified and removed are not limited to oxygen like Ca but also iron, nickel, chromium and the like.

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EXAMPLE A high-purity zirconium ingot having a diameter of 85 mm and a length of 150 mm was melted by an electron beam melting method and continuously cast using the apparatus shown in FIG. The raw material electrode is a molten salt electrolyzed sponge Zr, and the molten metal temperature in the cold hearth 2 and the water-cooled copper mold 1 is 1950 ° C.
The output of the electron beam 5 was 200 kW, and the pressure in the melt chamber containing the entire apparatus of FIG. 1 was 10 ⁻⁴ mbar. Zirconium hydride (bulk specific gravity 1.25 g / cm ³ )
Has an average size of 3 mm, and 1 equivalent of hydrogen was added to the oxygen concentration of the raw material. The test result is ZrH
₂ is shown in Table 2 together with a comparative example without addition.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Toshihiro Yano 3453 Miyata-cho, Hitachi-shi, Ibaraki Nikko Special Metals Co., Ltd.

Claims (20)

[Claims] 1. Ti, Zr, Hf, Nb, Ta, W by electron beam melting, plasma melting or vacuum arc melting.
And a method of producing a metal material or an alloy material by melting a raw material made of one metal selected from the group consisting of and Mo or an alloy containing the metal as a main component and containing an alloying element. Alternatively, the hydride of the alloy element and the molten metal of the metal or alloy are brought into contact with each other, and the method of producing the hydride of the alloy element and the metal material or the alloy material amount. 2. Ti having an oxygen concentration of 5000 ppm or less,
Manufacture of a metal material or an alloy material by melting a raw material made of a metal selected from the group consisting of Zr, Hf, Nb, Ta, W and Mo or an alloy containing this metal as a main component and containing an alloying element The method for producing a metal material or alloy material according to claim 1, wherein the hydride of the metal or the hydride of the alloy element is brought into contact with the molten metal of the metal or alloy. 3. The method for producing a metal material or an alloy material according to claim 1, wherein the amount of the hydride is 10 equivalent or less of the amount of oxygen in the raw material in terms of hydrogen. 4. The hydride is contacted with the molten metal in a lump or block form.
4. The method for producing a metal material or an alloy material according to any one of 1 to 3. 5. The method for producing a metal material or an alloy material according to claim 4, wherein the hydride has a size of 20 mm or less. 6. The method for producing a metal material or an alloy material according to claim 4, wherein the hydride is added to the molten metal. 7. The hydride is added to a copper mold in which the molten metal is cast.
A method for producing the described metal material or alloy material. 8. The method for producing a metal material or an alloy material according to claim 6, wherein the hydride is added to cold hearth stored before the molten metal is cast into a copper mold. 9. The method for producing a metal material or an alloy material according to claim 1, wherein the hydride is added to the raw material. 10. The method for producing a metal material or an alloy material according to claim 9, wherein powdered hydride is combined with the metal or alloy as the raw material. 11. The method according to claim 1, wherein the raw material is sponge metal or alloy.
A method for producing the described metal material or alloy material. 12. The method for producing a metal material or alloy material according to claim 1, wherein the raw material is a molten salt electrolyzed metal or alloy. 13. A refining agent for removing impurities of one metal selected from the group consisting of Ti, Zr, Hf, Nb, Ta, W and Mo or an alloy containing the metal as a main component and containing an alloying element. A refining agent for a metal material or an alloy material, comprising a hydride of the one kind of metal. 14. The alloy element is one or more metals selected from the group consisting of Ti, Zr, Hf, Nb, Ta, W and Mo other than the one metal, and the hydrogen The refining agent for an alloy material according to claim 13, wherein the compound is a hydride of the one or two metals. 15. A metal selected from the group consisting of Ti, Zr, Hf, Mo, Ta and W, containing one metal selected from the group consisting of Ti, Zr, Hf, Nb, Ta, W and Mo as a main component. A purifying agent for removing impurities of an alloy containing one or more kinds of alloying elements as described above, comprising a hydride of the alloying element. 16. The refining agent for a metal material or an alloy material according to claim 13, wherein the hydride is in the form of a lump or a block. 17. The refining agent for a metal material or an alloy material according to claim 16, wherein the hydride has a size of 20 mm or less. 18. The refining agent for a metal material or an alloy material according to claim 13, wherein the hydride is in a powder form. 19. An oxygen content of 100 ppm or less, a total amount of nitrogen, carbon and hydrogen of 30 ppm or less, iron, chromium, nickel of 50 ppm or less, hafnium of 500 ppm or less, and the balance substantially consisting of zirconium. Zirconium-based material with excellent corrosion resistance, characterized by: 20% by weight of one or two or more metals selected from the group consisting of Sn, Nb and Hf as an alloying element
The zirconium-based material having excellent corrosion resistance according to claim 19, characterized by containing: