JPH05140669A - Low oxygen ti-al alloy and its manufacture - Google Patents

Abstract

PURPOSE:To manufacture a low oxygen Ti Al alloy having <=200ppm oxygen concn. CONSTITUTION:In the method for melting an alloy series essentially consisting of Ti-Al, a Ti Al alloy is melted and held in a calcia crucible, which is mixed with a Ca source, and deoxidation is executed. The obtd. material is, as a melting raw material, melted in an atmosphere of an inert gas under a pressure reduced more than the atmospheric pressure or in a vacuum atmosphere by a melting method using no refractories, and the molten metal is held, by which Ca is forcedly evaporated away.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-purity Ti-Al-based alloy that has been partially put into practical use as a lightweight heat-resistant material or a sputtering target material. More specifically, it is a low-oxygen Ti-Al-based alloy and its production. It is about the method.

[0002]

2. Description of the Related Art In various industrial fields such as aircraft, automobiles, chemical plants, and tools, demands for improvement of engine efficiency, reduction of product cost, and extension of life have become stronger than ever before. Strength, elastic modulus, heat resistance,
The advent of high-performance and high-performance materials such as corrosion resistance is expected.

As a material satisfying such a demand, Ni
-Al-based, Fe-Al-based, and Ti-Al-based intermetallic compounds are available. In particular, Ti-Al-based intermetallic compounds are lightweight,
Since it has excellent characteristics such as high elastic modulus and high heat resistance, great expectations are placed on it.

Ti-Al having such excellent characteristics
When a Ti-based alloy is produced, Ti-Al-based alloys are chemically active due to their constituent components, and therefore pure Ti, pure Al, and additional elements such as a third element are vacuum arc melted in an inert gas atmosphere. It is manufactured by melting by plasma melting, electron beam melting, induction melting method using water-cooled split copper crucible, etc.

[0005]

In order that the Ti--Al alloy having excellent properties as described above can be used as a practical material, it is possible to improve the drawbacks of this material, that is, improve the workability and improve the room temperature. Improvement of ductility is indispensable, and for this reason, there is a strong demand for uniformity of components in the ingot and reduction of oxygen.

However, in the above-mentioned manufacturing method, it is difficult to expect a refining effect, and therefore, the purity depends on the melting raw material, the oxygen concentration is 200 ppm or less, and a uniform Ti-Al alloy without component segregation is obtained. Not obtained. The problems of each dissolution method are described below.

When a Ti-Al alloy is produced by vacuum arc melting, granular or lumpy raw materials of Ti and Al are compression-molded into a rod shape, and this compact is arc-melted under vacuum as a consumable electrode. Since the melting points of Ti and Al that are different from each other are significantly different, the melting rates of Ti and Al are different. As a result, Ti is mixed into the ingot in an unmelted state, or the stirring force in the molten metal pool at the time of melting is insufficient. Pure Ti, pure Al
However, it is difficult to produce a homogeneous ingot because segregation of component elements easily occurs because there is no time for uniform mixing. Also,
The purity also depends on the raw material purity, and high purity cannot be expected.

In plasma arc melting and electron beam melting, the bulk or granular pure Ti or pure Al, which is the raw material, is melted in a cold hearth and then poured into a water-cooled mold, or the raw material is directly used without using the cold hearth. Melting while charging in the mold, it is common to take a method such as making an ingot, but both segregation due to insufficient stirring force in the molten metal pool, melting point, similar to the above vacuum arc melting Due to the difference, the unmelting is likely to occur, and it is difficult to obtain a homogeneous ingot. The same applies to the purity.

In the induction melting method using a water-cooled split copper crucible disclosed in, for example, Japanese Patent Publication No. 3-44133, a molten metal skull (solidified shell) formed by the cooling effect from the water-cooled split copper crucible is melted. Since the metal is held and the molten metal is held in a parabolic shape by the electromagnetic force from the induction coil, there is less contact with the crucible material, less melting is possible, and the stirring force in the molten metal pool is also large. Therefore, it has an advantage that a uniform ingot can be obtained without segregation of components, but with respect to purity, it does not have a refining effect, depends on a melting raw material, and high purification cannot be expected.

The present invention has been made to solve the above problems, and in the melting of an alloy system containing Ti--Al as a main component, deoxidizing with Ca and removing excess Ca by evaporation. And high purity low oxygen T
It is an object to provide an i-Al alloy and a method for manufacturing the same.

[0011]

The present invention has been achieved as a result of research conducted by researchers on a high-purity low-oxygen Ti-Al alloy and a method for producing the same. The first invention is Ti. In the melting of an alloy system containing -Al as a main component, a Ti-Al system alloy is melted and held in a calcia crucible, and a Ca source is added to this to deoxidize the resulting material, A method for producing a low oxygen Ti-Al-based alloy in which Ca is forcibly evaporated and removed by melting by holding a molten metal in a melting method that does not use refractory in an inert gas atmosphere or a vacuum atmosphere under a reduced pressure below atmospheric pressure. Is.

A second aspect of the invention is to melt and hold a Ti-Al alloy by an induction melting method using a water-cooled split copper crucible in the melting of an alloy system containing Ti-Al as a main component, and to add Ca to this. It is a method for producing a low oxygen Ti-Al based alloy in which Ca is forcibly evaporated and removed by adding and deoxidizing and holding the molten metal in an inert gas atmosphere or a vacuum atmosphere under reduced pressure from atmospheric pressure.

A third invention is a low oxygen Ti-A produced by the method according to claim 1 or 2 and having an oxygen content of 200 ppm or less.
It is an l-based alloy.

[0014]

The present invention will be described in detail below. Ti-Al
In the melting of an alloy system containing as a main component, when a Ti—Al system alloy is melted and held in a calcia crucible and Ca is added to this to deoxidize it, excess Ca remains. The low-oxygen and high-calcium Ti-Al-based alloy thus obtained is further melted by a melting method that does not use refractory material, the molten metal is held under reduced pressure, and Ca is forcibly removed by evaporation to obtain a uniform solution. A low oxygen Ti-Al based alloy can be produced. Further, by melting in an inert gas atmosphere or a vacuum atmosphere, it is possible to prevent oxidation of the chemically active molten metal.

As a melting method without using refractory, an induction melting method using a water-cooled split copper crucible is suitable, and when remelting under reduced pressure, a low oxygen uniform Ti-Al alloy can be produced. It will be possible. In the induction melting method using a water-cooled split copper crucible, the molten metal is held in a parabolic shape by the electromagnetic force from the induction coil, so melting with less contact with the crucible material and less contamination is possible, and in the molten metal pool. Since the stirring power of is also large, a uniform ingot can be obtained without segregation of components. It is also possible to adjust the components to obtain an ingot having a final target composition. Although the melting method is described as using no refractory, this is in the essential sense, and refractory or the like filled between the segments (divided portions of the divided copper crucible) is not included in this.

By the above-mentioned melting method, a high-purity low-oxygen Ti-Al alloy having an oxygen content of 200 ppm or less can be obtained. The alloy thus obtained has uniform components and low oxygen content, so that it is difficult to work and the ductility at room temperature is also improved.

The present invention is not limited to the Ti-Al binary alloy, but Cr, M which has the effect of increasing the ductility at room temperature.
n, V, Mo, W, Nb, which has the effect of increasing high temperature strength,
Since the components can be adjusted by adding Ta, Y, etc., which has the effect of increasing heat resistance, the present invention can be widely applied to Ti-Al alloys.

[0018]

EXAMPLES Examples will be described below. Initial melting raw material of chemical composition shown in Table 1, Ti: 6.5kg and Al: 3.5k
Dissolve and hold g in a calcia crucible and add Ca:
Add 30-40g to deoxidize, Ti with low oxygen and high calcium
An ingot of Al alloy was produced. The chemical composition of this ingot is shown in Table 1.

Further, the ingot is melted by an induction melting method using a water-cooled split copper crucible, and the molten metal is kept under reduced pressure.
Ca was forcibly removed by evaporation. Table 1 shows the chemical composition of the molten metal after removing Ca by evaporation and the chemical composition of the cast material after casting.

As shown in Table 1, the oxygen concentration of the initially dissolved raw material Ti is 850 ppm, but according to the present invention, the oxygen concentration is 200 p
A uniform ingot with low oxygen below pm and no segregation of components was obtained. Similar results were obtained when the solution was dissolved by an induction melting method using a water-cooled split copper crucible instead of the calcia crucible.

[0021]

[Table 1]

[0022]

INDUSTRIAL APPLICABILITY The present invention, in the melting of an alloy system containing Ti-Al as a main component, deoxidizes with Ca, evaporates and removes excess Ca, and uniformly dissolves without contamination to obtain a high purity, low oxygen content. The present invention provides a Ti-Al alloy and a method for producing the same, and according to the present invention, an oxygen concentration is low oxygen of 200 ppm or less, and a uniform ingot without segregation of components can be produced. As a result, it is possible to obtain a Ti-Al-based alloy with improved hard workability and improved ductility at room temperature.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Internal reference number FI technical display location // C22C 14/00 Z 8825-4K (72) Inventor Teruaki Ishii 6 Kamiyatani, Suma-ku, Kobe City, Hyogo Prefecture -3-107- 302 (72) Inventor Tadao Miyamoto 2-10-6 Kitaoki, Higashinada-ku, Kobe-shi, Hyogo W6204 (72) Inventor Mamoru Onishi 54 Kamaya, Imada-cho, Taki-gun, Hyogo Prefecture

Claims (3)

[Claims] 1. A material obtained by melting and holding a Ti—Al alloy in a calcia crucible, and adding a Ca source to it to perform deoxidation in the melting of an alloy system containing Ti—Al as a main component. Is used as a melting raw material in an inert gas atmosphere or a vacuum atmosphere under a reduced pressure below atmospheric pressure, is melted by a melting method that does not use a refractory, and the molten metal is retained to forcibly evaporate and remove Ca. A method for producing a low oxygen Ti-Al alloy. 2. In the melting of an alloy system containing Ti--Al as a main component, the Ti--Al system alloy is melted and held by an induction melting method using a water-cooled split copper crucible, and Ca is added to this to remove the Ti--Al system alloy. Low oxygen Ti-A characterized by forcibly evaporating and removing Ca by holding the molten metal in an inert gas atmosphere or a vacuum atmosphere under reduced pressure below atmospheric pressure.
Method for producing l-based alloy. 3. A low-oxygen Ti—Al based alloy having an oxygen content of 200 ppm or less produced by the method according to claim 1.