JPH07179965A - Titanium-niobium alloy capable of highly airtightly joining to alumina and excellent in degassing property - Google Patents

Abstract

PURPOSE:To obtain a titanium-niobium alloy capable of highly airtightly joining to alumina and excellent in degassing property by specifying a composition consisting of Nb, Co, and Ti and properly controlling C, N, and O as impurities. CONSTITUTION:This alloy is a titanium-niobium alloy having a composition which consists of, by weight, 40-60% Nb, 0.5-4.0% Co, and the balance Ti with inevitable impurities and in which the amounts of C, N, and 0 as impurity elements are specified to <=0.02%, <=0.02%, and <=0.06%, respectively. This alloy is capable of highly airtightly joining to alumina up to a temp. as high as about 800 deg.C and excellent in degassing property and hot workability. If necessary, this alloy can further contain 0.02-1.0% of one or more platinum series metals among Pd, Pt, Rh, Ru, Re, and Os and/or 0.02-0.50% of one or more kinds among rare earth elements consisting of La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho and Er, and Y.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is titanium niobium which is capable of forming a highly airtight joint with alumina even at a high temperature of about 800 ° C. and has excellent degassing characteristics, and is suitable for a current introducing terminal flange of an ultrahigh vacuum container. Regarding alloys.

[0002]

2. Description of the Related Art With recent advances in vacuum technology, the degree of vacuum that can be reached has expanded to a region of ultrahigh vacuum of 10 ^-10 Pa. Such an ultra-vacuum is obtained not only by the development of a vacuum pump but also by significantly improving the degassing characteristics of the material used as the vacuum container.

As such an ultra-high vacuum container material, the applicant of the present invention has previously proposed a titanium alloy having extremely good degassing characteristics (Japanese Patent Application No. 4-224154), and using this titanium alloy. It is said that an ultrahigh vacuum can be reached easily by making a vacuum container.

However, in the vacuum vessel using the above titanium alloy, although degassing from the vessel is significantly reduced,
It has not reached the level of vacuum expected from the properties of the material itself.

[0005]

As a result of detailed examination of the reason why the degree of vacuum is not sufficiently lowered, it has been found that the cause is a current introducing terminal which is indispensable for performing work in a vacuum container. Usually, a current introduction terminal used in a high vacuum vacuum container is formed by joining alumina, which is an insulator, to a flange made of stainless steel via Kovar, and further, adding the insulator and electrodes such as tungsten and molybdenum to Mo-Mn.
And a structure in which they are joined via Ni plating. Since the current introducing terminal is attached to the stainless steel flange in this manner, degassing from the stainless steel flange has a great influence on the ultimate vacuum. In addition, during the heat treatment of the vacuum container (baking: processing to remove the gas adsorbed on the inner wall of the container after releasing the vacuum), which is indispensable for obtaining a high vacuum, the stainless steel current introduction terminal flange and vacuum container It was also found that there is a problem that a gap is generated between the current introducing terminal flange and the vacuum container due to the difference in thermal expansion from the above-mentioned titanium alloy used, resulting in vacuum deterioration.

Therefore, in order to solve this problem, the current introduction terminal flange was formed by using the titanium alloy excellent in the degassing characteristics and studied. However, in the case where the current introduction terminal used in the usual current introduction terminal and the alumina of the insulating portion are joined by the Mo-Mn method via Kovar, (1) the joining metal Kovar (Fe-17 %
A large amount of gas is released from Co-29% Ni). (2) There was a problem that it was impossible to weld Kovar and a titanium alloy as a flange material.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a titanium-niobium alloy capable of forming a highly airtight bond with alumina up to a high temperature of about 800 ° C. and having excellent degassing characteristics. And

[0008]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to find a material that has a good degassing property and can be joined to alumina with excellent airtightness. As a result, (1) In the case of extremely high vacuum , The most problematic adsorption gas is desorption of oxygen and hydrogen, and it is necessary to have a function to fix it. (2) The current terminal used for the ultra-high vacuum container is During heat treatment (baking) to remove the gas adsorbed on the inner wall surface and during use, it undergoes repeated heat cycles such as heat generation of the current-introducing terminal metal itself. It became clear that matching must be performed up to a high temperature of about 800 ° C.

Therefore, in consideration of the gas releasing property of the material and the bondability with the titanium alloy (used as a flange material) excellent in the degassing property shown in Japanese Patent Application No. 4-224154, the titanium alloy is Among them, research was repeated on those satisfying the above conditions.

As a result, the titanium-niobium alloy, which has a thermal expansion coefficient relatively close to that of alumina, is added as a base to which Co capable of fixing hydrogen in the residual gas is added, and the gas component is further reduced. It has been found that a material capable of high bonding and having excellent degassing characteristics can be obtained.

The present invention has been made on the basis of the above-mentioned findings of the inventors of the present application. Firstly, in% by weight, Nb: 40.
% Or more and 60% or less, Co: 0.5% or more and 4.0% or less, and C, N and O as impurity elements are contained in C:
0.02% or less, N: 0.02% or less, O: 0.06%
Specified below, consisting of the balance Ti and unavoidable impurities,
It is intended to provide a titanium-niobium alloy having excellent degassing characteristics, which enables highly airtight bonding with alumina.

Secondly, by weight%, Nb: 40% or more 60
% Or less, Co: 0.5% or more and 4.0% or less, Pd, P
0.02% or more and 1.0 or more of at least one platinum-based metal selected from the group consisting of t, Rh, Ru, Re and Os.
% Or less, C, N and O as impurity elements are respectively C: 0.02% or less, N: 0.02% or less, O: 0.0
Provided is a titanium-niobium alloy having a degassing property of 6% or less, which is composed of the balance Ti and unavoidable impurities and can be bonded to alumina with high airtightness.

Thirdly, in% by weight, Nb: 40% or more 60
% Or less, Co: 0.5% or more and 4.0% or less, La, C
e, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er
Containing at least one selected from the group consisting of the rare earth elements and Y of 0.02% or more and 0.50% or less, and each of C, N and O as impurity elements C: 0.02% or less,
N: 0.02% or less, O: 0.06% or less, and a titanium-niobium alloy having excellent degassing characteristics, which is composed of the balance Ti and unavoidable impurities and can be bonded to alumina with high airtightness. Is.

Fourth, by weight%, Nb: 40% or more 60
% Or less, Co: 0.5% or more and 4.0% or less, Pd, P
0.02% or more and 1.0 or more of at least one platinum-based metal selected from the group consisting of t, Rh, Ru, Re and Os.
% Or less, La, Ce, Pr, Nd, Sm, Gd, Tb,
It contains 0.02% or more and 0.50% or less of at least one selected from the group consisting of rare earth elements such as Dy, Ho and Er and Y, and C, N and O as impurity elements are C:
0.02% or less, N: 0.02% or less, O: 0.06%
Specified below, consisting of the balance Ti and unavoidable impurities,
It is intended to provide a titanium-niobium alloy having excellent degassing characteristics, which enables highly airtight bonding with alumina.

[0015]

[Function] The reason for limiting the additive elements will be described below. In addition, all of the following percentages represent% by weight. Nb; Nb is an extremely important element for matching the coefficient of thermal expansion of titanium alloy with alumina. However,
As shown in, when Nb is less than 40% and more than 60%, the difference in the coefficient of thermal expansion with alumina becomes high at high or low temperatures. Therefore, the amount of Nb is specified to be 40% or more and 60% or less. Co; Co is titanium or niobium and TiCo ₂ , NbCo
It is an extremely important element because it forms an intermetallic compound of ₂ , which fixes hydrogen in the residual gas. However, if such an effect is added in an amount of less than 0.5%, it is not sufficient, and if it is added in an amount of more than 4.0%, the workability of the material is significantly reduced. Therefore, the Co content is 0.5% or more and 4.0% or more.
It is specified below.

Although these are essential components in the present invention, at least one platinum-based metal selected from the group consisting of Pd, Pt, Rh, Ru, Re and Os, and L
a, Ce, Pr, Nd, Sm, Gd, Tb, Dy, H
It is also possible to add at least one or both selected from the group consisting of rare earth elements of o and Er and Y. Pd, Pt, Ru, Rh, Re, Os; these platinum-based metal elements act as a catalyst that traps molecular hydrogen that fixes the gas remaining in the ultra-high vacuum container on the surface and separates it into atomic hydrogen. have. By adding at least one of these, hydrogen in the residual gas can be fixed and vacuum deterioration can be prevented. In order to exert such a function, it is necessary to add at least one of the above elements in a total amount of 0.02% or more. However, if the total amount added exceeds 1.0%, the workability is significantly reduced. Therefore, it is desirable to add at least one of the above elements in the range of 0.02 to 1.0% from the viewpoint of obtaining more excellent degassing characteristics. La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, H
o, Er, and Y; these elements fix oxygen dissolved in the material as an oxide by internal oxidation, and suppress the diffusion of dissolved oxygen from the inside of the solid to the surface. Such functions are La, Ce, Pr, Nd, Sm, Tb, D
It can be obtained by adding y, Ho, Er and Y alone,
Alternatively, even in the case of compound addition in the form of misch metal, it is effectively exhibited when 0.02% or more is added in total. However, when at least one of these is added in a total amount of more than 0.50%, the precipitated oxides significantly reduce ductility and workability. Therefore, 0.02 of at least one of these elements
It is desirable to add in the range of 0.50%.

The C, N and O gas components are limited as follows. C: When C is solid-dissolved in the material, it diffuses to the surface and combines with oxygen in the residual gas to generate CO gas, so it must be reduced as much as possible. However, when the content is 0.02% or less, CO due to diffusion from the inside of such a solid is generated.
The amount of released gas has almost no effect on the target vacuum degree of 10 ⁻¹⁰ Pa. Therefore, C is specified to be 0.02% or less. Similarly, when N: N is also solid-dissolved in the material, it may diffuse from the inside to the surface and become N ₂ gas, which may be released. However, at the vacuum degree of 10 ^-10 Pa targeted in the present invention, if the N content is 0.02% or less, the N ₂ gas does not significantly reduce the vacuum degree. Therefore, N is 0.02% or less. O; O is an impurity that requires the most control when considering the release of gas from the surface, because the solid solution range is large in the case of titanium alloy. However, when the content is 0.06% or less, the release of O ² gas due to such diffusion from the inside of the solid has almost no effect at the target vacuum degree of 10 ^-10 P. Therefore, O is 0.06% or less.

[0018]

EXAMPLES Alloys having the compositions shown in Table 1 were melted in an arc melting furnace, subjected to hot rolling and heat treatment, and then subjected to various tests. In Table 1, numbers 1 to 9 are examples within the scope of the present invention, and numbers 10 to 19 are comparative examples outside the range.

[0019]

[Table 1]

Regarding the workability of these test materials, paying attention to cracks after hot rolling, no cracks were observed (no cracks), cracks from the edges were 10 mm or less (small), 1
It was arranged as a thing (large) exceeding 0 mm. Moreover, in order to examine the bondability with alumina up to a high temperature, Mo--Mn
The bonding strength of the one bonded to alumina by the method is measured, and the bonding strength after the thermal cycle of 10 times from room temperature to 800 ° C. is measured, and the ratio of these (bonding after thermal cycling is measured. Intensity ratio: When intensity does not change 1.
The soundness due to the thermal cycle of the joint was evaluated by taking 0). The results are shown in Table 2.

Further, Ti-2Co- which is a flange material
The 0.25Pd-0.05Y alloy and these test materials were welded and joined to alumina by the Mo-Mn method.
The blind flange shown in Fig. 2 was produced and the leak characteristics were evaluated. The results are also shown in Table 2. The leakage characteristics of the current introducing terminal (conventional material) using the conventional Kovar are also shown.

[0022]

[Table 2]

As is clear from Table 2, the alloy materials of Nos. 1 to 9 which are examples of the present invention have little or no cracks during hot working, and change in joint strength due to heat cycle. None, and the leak amount is all 5 × 10 ^-14 torr ・ cc
Good characteristics below / s were exhibited.

On the other hand, in Comparative Examples Nos. 10 and 11 in which the amount of Nb was out of the range of the present invention, the result was that the bonding strength decreased due to the thermal cycle. In addition, Co, platinum-based metal,
No. 13, 1 in which rare earth or Y is beyond the scope of the present invention
Since Nos. 7 and 18 were extremely inferior in hot workability, they could not be used in the subsequent tests. No. 12, in which Co was less than the amount specified in the present invention, did not significantly improve the outgassing characteristics from the conventional material. Similarly, Nos. 14, 15, and 16 containing the gas component in an amount exceeding the amount specified in the present invention also exhibited the leak characteristics comparable to those of the conventional material.

[0025]

As described above, according to the present invention,
Provided is a titanium-niobium alloy which can be bonded to alumina at a high temperature of about 800 ° C. with high airtightness and has excellent degassing characteristics. Further, the alloy of the present invention has good hot workability.

[Brief description of drawings]

FIG. 1 is a view showing a comparison between the thermal expansion coefficient of Ti—Nb alloy and the thermal expansion coefficient of alumina from room temperature to high temperature.

FIG. 2 is a schematic diagram showing a sample for evaluating leak characteristics.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nakanose Onna 2 Takara-cho, Kanagawa-ku, Yokohama, Kanagawa Nissan Motor Co., Ltd. (72) Seiji Ishimoto 2 Takara-cho, Kanagawa-ku, Yokohama, Kanagawa Nissan Motor Co., Ltd. Within

Claims (4)

[Claims] 1. By weight%, Nb: 40% or more and 60% or less, Co: 0.5% or more and 4.0% or less are contained, and C, N and O as impurity elements are respectively C: 0.02. %Less than,
N: 0.02% or less, O: 0.06% or less, and a titanium-niobium alloy excellent in degassing properties, which is composed of the balance Ti and unavoidable impurities and can be bonded to alumina with high airtightness. 2. By weight%, Nb: 40% or more and 60% or less, Co: 0.5% or more and 4.0% or less, Pd, Pt, R
It contains at least one platinum-based metal selected from the group consisting of h, Ru, Re and Os in an amount of 0.02% or more and 1.0% or less, and C, N and O as impurity elements are C:
0.02% or less, N: 0.02% or less, O: 0.06%
Specified below, consisting of the balance Ti and unavoidable impurities,
A titanium-niobium alloy with excellent degassing properties that enables highly airtight bonding with alumina. 3. By weight%, Nb: 40% or more and 60% or less, Co: 0.5% or more and 4.0% or less, La, Ce, P.
R, Nd, Sm, Gd, Tb, Dy, Ho, Er at least one selected from the group consisting of rare earth elements and Y are contained in 0.02% or more and 0.50% or less, and C as an impurity element, N and O are respectively C: 0.02% or less, N:
0.02% or less, O: 0.06% or less, balance T
A titanium-niobium alloy having excellent degassing properties, which is composed of i and unavoidable impurities and can be bonded to alumina with high airtightness. 4. In% by weight, Nb: 40% or more and 60% or less, Co: 0.5% or more and 4.0% or less, Pd, Pt, R
0.02% to 1.0% of at least one platinum-based metal selected from the group consisting of h, Ru, Re and Os, La, Ce, Pr, Nd, Sm, Gd, Tb, D
Containing 0.02% or more and 0.50% or less of at least one selected from the group consisting of y, Ho, Er rare earth elements and Y, and C, N and O as impurity elements are C:
0.02% or less, N: 0.02% or less, O: 0.06%
Specified below, consisting of the balance Ti and unavoidable impurities,
A titanium-niobium alloy with excellent degassing properties that enables highly airtight bonding with alumina.