JPS60224742A - Rhenium-tungsten alloy - Google Patents

Abstract

PURPOSE:To obtain an Re-W alloy having high workability and superior strength characteristics at high temp. by adding a very small amount of Si, Al or K to an Re-W alloy contg. a prescribed amount of Re. CONSTITUTION:This Re-W alloy consists of 0.2-26wt% Re, 50-100ppm one or more among Si, Al and K, and the balance W. The alloy has a recrystallized structure elongated in the axial direction, and grain boundaries interlock in the crystal structure. Si, Al and K added make arranged micropores in the structure of the alloy by heat treatment after working. In the composition of the alloy, the K content is preferably regulated to 50-80ppm. The alloy can be easily formed into a wire by drawing, and this wire is applicable to a heater for a flash bulb or a filament for an vibration resistant pilot lamp.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a rhenium-tungsten alloy with high-temperature strength properties and workability. For example, 3% rhenium-tungsten alloy # has a high electrical resistance, a large elongation in the second crystal region, excellent high-temperature strength, and no significant change in melting point.For example, 3% rhenium-tungsten alloy It is used in filaments for commercial and illot lamps, cathode heaters for cathode ray tubes, etc.

However, the conventional rhenium-tungsten alloy wire,
The secondary recrystallized structure tends to form grain boundaries perpendicular to the axial direction, and deformation and wire breakage are likely to occur due to grain boundary slip when used at high temperatures, and the recrystallization temperature is low and unstable, resulting in poor high-temperature strength. There was a problem.

Furthermore, the rhenium-tungsten alloy has extremely poor workability, with a yield of about 40%, and improvements are being sought in this respect as well.

However, when high temperature strength is improved, workability deteriorates, and on the other hand, when workability is improved, excellent high temperature strength cannot be obtained, and it has been difficult to obtain a rhenium-tungsten alloy that satisfies both properties.

[Purpose of the invention]

An object of the present invention is to provide a rhenium-tungsten alloy that has good workability and even better high-temperature strength properties. Specifically, the purpose is to provide a rhenium-tungsten alloy that has a yield p of 70% or more as workability and a sag value (sagging value) of 12 or less as high-temperature properties.

[Summary of the invention]

As a result of conducting research on the manufacturing method of the above-mentioned alloy, the present inventors discovered that when a predetermined amount of silicon, aluminum, and potassium, especially potassium, is added to a rhenium-tungsten alloy, the deformation of the alloy at high temperatures is suppressed. The inventors have discovered that the alloy of the present invention has been developed based on the findings that the alloy has a high processability and has good workability.

That is, the rhenium-tungsten alloy of the present invention has a rhenium content of 0.2 to 26 inches, silicon,
At least one selected from the group of aluminum and potassium
It is characterized by a seed content of 50 to 100 ppm, with the remainder being tungsten.

In the rhenium-tungsten alloy of the present invention, the recrystallized structure has an elongated shape in the axial direction, and the boundaries thereof are mutually interlocked (interlocking means intersecting in a zigzag manner).

In the rhenium-tungsten alloy of the present invention, rhenium is an essential component for increasing the toughness in the primary Mm region of tungsten, which is the base material.

If the content of rhenium is too small, it will not contribute to improving the toughness of the alloy, and its effect will be exhibited from 0.2% by weight or more. However, if the content is more than 1, it is not a waste of expensive rhenium, but it also causes a decrease in the workability of the alloy, so the content is limited to 26 or less. Preferably 1
~10% by weight.

In addition, the alloy examples of the present invention contain any one of silicon, aluminum, and potassium, or 2 ftli or more. These elements generate aligned micropores (referred to as micro-doped pores) in the structure of the alloy through heat treatment after processing, which will be described later, and the effect of these micro-doped pores causes the recrystallized structure to grow long and narrow. It is an element necessary for

In particular, potassium greatly contributes to this effect.

If the content is too small, it will not contribute to the above effect, and it is effective from 50 ppm or more.However, if the content is too large, the above-mentioned micro donopores will be formed larger than necessary and in large quantities, causing local damage. Defect holes are generated when the recrystallized structure becomes a hexagonal-shaped equiaxed crystal grain and aggregation and abnormal growth of doped holes occur, and when used at high temperatures, abnormal deformation due to grain boundary slip occurs. This can easily cause intergranular cracks, intergranular cracks, and intragranular cracks originating from defect holes, which can also lead to a decrease in the workability of the alloy, and when the alloy is used in lamp filaments, it can reduce its blackening resistance. Therefore, it should be 1100pp or less. In particular, 1 potassium is preferably 50 to 80 ppm.

The rhenium-tungsten alloy of the present invention can be manufactured by the method described below. That is, tungsten oxide powder is subjected to doping treatment, and then reduced with hydrogen to produce tungsten powder that has adsorbed a dopant. Next, this powder is treated with a strong acid or a strong alkali, and then washed with water to separate the secondary particles in the powder into individual unit particles to produce dosed tungsten powder. Next, a specified amount of rhenium powder is mixed with this powder, and the subsequent sintering is performed by a conventional method. Note that this alloy can be easily made into a wire rod by subjecting it to rolling and wire drawing treatments. The alloy wire produced in this manner has recrystallized grains adjusted to have a crystalline structure that is elongated in the axial direction of the wire, and whose boundaries are interlocked with each other. This crystal structure state is most suitable for strengthening deformation resistance at high temperatures, resulting in an alloy wire with less sagging or deformation, which allows for higher lighting temperatures and longer periods of time than conventional rhenium-tungsten alloy wires. It can be used even under harsh conditions.

[Embodiments of the invention]

Potassium silicate aqueous solutions, potassium chloride aqueous solutions, and aluminum chloride aqueous solutions of various concentrations were prepared.

In a mixed solution of these aqueous solutions, particle size 5.
1000 r'i of μm tungsten trioxide powder was added and evaporated to dryness on a hot water bath. During drying, it was stirred occasionally to prevent segregation. The dried powder was placed in a nickel boat and subjected to hydrogen reduction to obtain dogutungesten powder. However, the above reduction conditions are 600.680 as the first reduction.
Heated at 700.710°C in a hydrogen atmosphere for 20 minutes each, and further reduced to 700.750.800°85 as a second reduction.
It was heated at 0° C. for 20 minutes each.

Next, doped tungsten powder (1-3 μm).

Rhenium powder (2-4 μm), isoamyl acetate (reagent grade)
A predetermined amount of t was placed in a stainless steel pit and pulverized and mixed for 4 hours using an ultra-hard tungsten alloy ball. The mixture was then dried in a hot water bath for 3 hours to evaporate the isoamyl acetate. During this time, sufficient care was taken to prevent segregation. Then, it was crushed finely and passed through a 300 mesh sieve.

This powder was pre-pressed at 180 kp/c1n” and
A molded body of -X 6 w x 200 wa was prepared, and this molded body was preliminarily sintered by heating at 1200''C for 15 minutes in a hydrogen atmosphere.Thereafter, it was heated with electricity in a hydrogen atmosphere to form a sintered body. This sintered body was placed in a hydrogen atmosphere again for 1
After heating at 850 DEG C. for 10 minutes, the current heating was repeated again with iL'T to form a rhenium-tungsten alloy with each component cap as shown in the table.

Next, this rhenium-tungsten alloy was subjected to a conventional suede song and wire drawing process to obtain a wire rod having a wire diameter of 0.39 m.

The sag resistance, recrystallization temperature, and yield were measured for these wire rods.

The sag value is J for a wire with a wire diameter of 0.39wm.
It was measured by the heat deformation test of 4.5 of IS H4460-1976. In addition, at this time, the test current is pc x
After changing the sail from 80 to FCXo and 90 IC, the test piece was held.

Further, the yield was measured based on how many kf of wire having a diameter of 39 mm was obtained when the sintered body 10 was processed.

Using this table, each ip* of the example of the present invention and the comparative example
I will discuss the comparison regarding gender.

First, regarding the sag value, compared to Comparative Example (1), Example 11
1, +2], (3) is as low as 8.0fi, and the sag resistance is improved.

Next, the secondary recrystallization temperature is compared with Comparative Example tllK and Example t
l+, 12+, +3] is 2600-2700
It is stable at temperatures as high as ℃.

Finally, regarding the yield, Examples fi+, +21, +31 are 75 to 80% compared to Comparative Example (2).
However, the speed of walking has improved by about 2 times.

Therefore, Examples +11, +21,
It can be understood that +31 indicates good high-temperature strength and good workability.

In addition, when the alloys of the present invention in the table were cut along the line axis direction and the cut surfaces were observed under a microscope, it was found that all had long crystal structures interlocked with each other in the axial direction.

〔Effect of the invention〕

As is clear from the above results, the rhenium-tungsten alloy of the present invention has extremely superior high-temperature strength properties and workability compared to conventional ones.

Therefore, it is useful as a material for filaments in earthquake-resistant light bulbs and as a material for cathode heaters in cathode ray tubes.

Claims (1)

[Claims] 1. In terms of weight ratio, the content of rhenium is 2 to 26 ppm, the content of at least one selected from the group of silicon, aluminum, and potassium is 50 to 1100 pp, and the balance is tungsten. A rhenium-tungsten alloy characterized by: 2. The rhenium-tungsten alloy according to claim 1, wherein the potassium content is 50 to 80 ppm.