JPS60194042A - Tungsten base alloy for electronic apparatus - Google Patents

Abstract

PURPOSE:To provide the titled alloy which is relatively low in initial cost and has good workability and strength by consisting the same of a specific compsn. ratio of Ta, Mo and W. CONSTITUTION:A tungsten-base alloy for electronic apparatus consists of 0.5- 2wt% Ta, <40% Mo and the balance substantially W. Mo having smaller specific gravity is added to the alloy to make the initial cost thereof lower than the initial cost of the alloy made of W alone. The workability is better and the strength is higher than pure W. Such alloy is adequate and exhibits a target effect particularly as a supporting material for a halogen lamp. Ta among the effective components of the above-mentioned alloy acts as a getter and if the content thereof is low, the effect is not thoroughly attained and if the content is too much, the alloy is uneconomical and is undesirable in terms of workability and strength. Mo is added at <40% to improve economy, workability, strength, etc. and the proper content thereof is selected according to applications. The above-mentioned alloy is easily produceable by a powder metallurgical method.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tungsten-based alloy used as a support material for a halogen lamp.

Tungsten and molybdenum are high-melting point metals that are similar to each other, and these alloys have properties such as electrical resistance and temperature coefficient that change rapidly depending on the composition, and are conventionally used in electronic materials. . In the above-mentioned alloy of tungsten and molybdenum, the specific gravity of molybdenum is considerably lower than that of tungsten, so the advantage of using this alloy is that the material cost is lower than making products of the same shape only from tungsten. It is generally said to have better workability and strength than pure tungsten.

This invention takes advantage of the characteristics of the above-mentioned tungsten and molybdenum alloy, and also provides an alloy that has a getter effect when used as a constituent material of halogen lamps, etc. and less than 40% molybdenum.

However, its gist is a tungsten-based alloy for electronic devices in which the remainder is essentially tungsten.

Among these active ingredients, tantalum (Ta) acts as a getter, and when the content of tantalum is reduced, the desired getter effect of adsorbing gases such as 02 and preventing the precipitation of needle-shaped tungsten crystals is achieved. not fully achieved. On the other hand, since tantalum is expensive, it is uneconomical to add it in large amounts, and it is also unfavorable in terms of workability and strength.As a result of considering these points, the preferable range for the content of tantalum is 0.5 to 2. % (weight %, the same applies hereinafter), and it is more preferably 0.5 to 1.5z, and 1 to 1z.
．． It has been found that 5% is more preferable.

Next, regarding the amount of molybdenum, the alloy of phosphorous (W) and molybdenum (No.) is a completely solid solution type alloy, and its properties change with the molybdenum content, so the desired amount can be determined depending on the application. You can choose any composition, but from the standpoint of economy, workability, strength, etc., for example, as a material for a halogen lamp, it is preferable to have a content of less than 40%, and more preferably 1% or more and less than 40%. preferable.

In addition to these ingredients, doping agents (S, AM, etc.)
It may also contain trace amounts of unavoidable impurities.

This alloy can be manufactured by powder metallurgy. For example, tantalum powder, tungsten powder, and molybdenum powder are blended in a desired ratio, thoroughly mixed, and then pressure-molded to form a green compact of a predetermined size. After presintering this compact at a relatively low temperature in a hydrogen atmosphere or the like, main sintering is performed at a high temperature to obtain an ingot. Handling in the above-mentioned pressure forming, presintering, main sintering, etc. is generally easier when the amount of molybdenum is larger. The obtained ingot is
The desired product is made by performing necessary plastic processing such as rolling, swaging, and wire drawing. Next, examples of the present invention will be described.

〔Example〕

-320 mesh tantalum powder, average particle size 3.5 microns (gm) tungsten powder and average particle size 4.2
Using micron molybdenum powder, no.

They were blended at the blending ratio shown in Table 1 and thoroughly mixed.

Table 1 The obtained mixed powder was press-molded at a pressure of 2 t/cm' to form a 15 x 15 x 400 (am) compact, and pre-fired at a maximum temperature of 1700°C in a hydrogen stream using an electric furnace. I made a conclusion. Next, a half-bell furnace (bell jar type heating furnace) was used as a sintering furnace, and main sintering was performed by directly applying electricity to the pre-sintered compact in a hydrogen stream. The maximum current in this case was approximately 90% of the melting current. The ingot obtained by this main sintering is subjected to a stepwise swaging process to form a round bar with a diameter of 3.0 mm, and then a drop rate of 8.
A wire rod with a diameter Q of 35+ am was obtained by drawing with a concentration of ~10%. In the middle of the above processing, the following intermediate annealing was performed. First, at the stage of diameter 3a+m, it was heated to 2m in an electric furnace at 1370℃ (hot zone length about 11i0c+a).
It was allowed to pass at a speed of 7 minutes, and then similar intermediate annealing was performed again at the stage of 1.8 mm in diameter.

The obtained alloy wire has a getter effect because it contains tantalum, and when we used it to make a prototype support material for a halogen lamp (a support material that also serves as a lead wire to support a tungsten filament), we found that it had sufficient strength. A product with excellent performance was obtained.

Patent applicant: Toho Metals Co., Ltd. Agent: Patent attorney Hiroshi Sugahara

Claims (1)

[Claims] (1) A tungsten-based alloy for electronic devices containing 0.5 to 2% tantalum and less than 40% molybdenum by weight, with the remainder being substantially tungsten.