JPH0448861B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to an amorphous alloy having a high crystallization temperature and a method for producing the same. (Prior Art) In recent years, various amorphous materials have been developed and are attracting a lot of attention in the field of metal materials. Unlike conventional crystalline alloys, these alloys are metals that do not have a crystal structure, and many of their properties are not found in conventional metal materials, such as mechanical properties, abrasion resistance, corrosion resistance, and soft magnetism. Because it is excellent in
As a material that can replace crystalline metals, various uses are being developed, and materials suitable for these uses are also being developed. These alloys can be produced by a vapor phase quenching method such as a sputtering method or a liquid quenching method, but the liquid quenching method, which has the highest productivity, is often used industrially. (Problems to be Solved by the Invention) The biggest problem with amorphous alloys is that they are thermally unstable. This is due to the fact that the amorphous state is a thermodynamically non-equilibrium metastable state, and can be said to be the fate of amorphous alloys. In other words, each amorphous alloy generally has its own unique crystallization temperature, and once that temperature is exceeded, it changes to a more thermally stable crystalline alloy, resulting in the superior properties observed in the amorphous state. All properties are lost. This crystallization temperature varies depending on the material, but is generally below the melting point measured in absolute temperature.
It is known that it takes a value of about 0.4 to 0.6 times.
Therefore, in order to obtain an amorphous alloy with a high crystallization temperature, an alloy with a high melting point must be made amorphous by a method such as a liquid quenching method. However, conventional liquid quenching equipment is often made for materials with relatively low melting points, such as iron-based alloys, and uses a method that heats a heat-resistant nozzle made of quartz or other material using resistance heating or high-frequency heating. Most of them are. Therefore, the maximum operating temperature is limited by the fire resistance of the nozzle material, and is 1200~
The maximum temperature is around 1400℃. Furthermore, as the temperature rises, the nozzle material and the alloy may react and contaminate the sample, so the types of alloys that can be rapidly cooled are limited. On the other hand, the Ta-Si-B ternary amorphous alloy, which has an extremely high melting point of approximately 2400°C, has a crystallization temperature of 800°C to 960°C, which causes problems with amorphous alloys. It has become possible to make significant improvements.
(Japanese Patent Application Laid-Open No. 61-012385) Furthermore, this Ta-Si-B ternary amorphous alloy is
Because it has excellent mechanical properties such as high strength and high hardness that are typical of general amorphous alloys, it can be used as a wear-resistant material, as a composite reinforcement for structural materials used at high temperatures, and as a Possible applications include materials for electrodes that involve a rise in temperature. However, when the Ta-Si-B amorphous alloy is actually used in a high-temperature environment, deterioration over time becomes a problem, so the maximum operating temperature range is
The temperature is limited to around 600℃. The present invention solves the problems of the prior art, has a high crystallization temperature, can withstand higher temperature environments than the Ta-based amorphous alloy, and has improved mechanical properties, corrosion resistance, etc. An object of the present invention is to provide an excellent Ta-W amorphous alloy and a method for manufacturing the same. (Means for solving the problem) The present invention is expressed by the formula (Ta ₁ −xWx)yBz, where x=0.01-0.8, y=0.7-0.9, z=0.1-0.3
It is a Ta-W based amorphous alloy characterized by the following. Furthermore, the present invention provides a manufacturing method for obtaining the Ta-W amorphous alloy, in which a raw material alloy having the same alloy composition as the Ta-W amorphous alloy is heated in a water-cooled metal The molten alloy is melted in a crucible and applied to the surface of a cooling roll that is rotating at high speed at a surface peripheral speed of 90 m/sec or more using a water-cooled metal nozzle or a nozzle made of a high melting point material. This is a method for producing a Ta--W amorphous alloy, which is characterized in that it is made amorphous by being injected and rapidly solidified. (Function) In Ta-W-B alloys, as shown in Examples later, the present inventors have found that an amorphous alloy can be obtained in a composition range of 70 at% to 90 at% of Ta and W in total. I found it. When the composition is outside this range, almost no amorphous structure is observed, and all the excellent properties characteristic of amorphous alloys are lost. Although the detailed reason why an amorphous phase is formed in this composition range is unknown, there is a general tendency for an amorphous phase to be formed near a eutectic composition, and this tendency is likely to apply in this case as well. Seem. In addition, the range of x was limited to 0.01 or more because
This is because the crystallization temperature becomes higher when W is added than when only Ta is added. Note that when the range of x exceeds 0.8, the crystallization temperature decreases, so x
Desirably within 0.8. The crystallization temperatures of these amorphous alloys range from 1000 to 1000, corresponding to their high melting points.
This is a high value of 1200℃. The mechanical properties of these amorphous alloys are high strength and hardness, as is commonly found in amorphous alloys. Also, in terms of corrosion resistance, it has corrosion resistance comparable to that of Ta and W. Next, the manufacturing method according to the present invention is a type of liquid quenching method, but since the raw material alloy is melted in a water-cooled metal crucible, almost no reaction occurs between the raw material alloy and the crucible metal. This is because if the crucible metal is water-cooled, even if high-temperature molten metal comes into contact with it, the temperature of the crucible metal is too low, making it extremely difficult for an alloying reaction to occur. The material of the crucible metal is preferably a material with high thermal conductivity in order to increase the water cooling effect. In addition, substances with high melting points are also suitable from the viewpoint of being difficult to react. For example, copper, silver, alloys thereof, tungsten, molybdenum, etc. can be considered. Further, as the melting means, well-known methods such as arc melting, plasma melting, electron beam melting, and laser beam melting can be used. The raw material alloy thus melted is injected onto the surface of a cooling roll rotating at high speed using a water-cooled metal nozzle or a nozzle made of a high-melting point material to form a quenched ribbon. At this time, the reason for passing the melt through the nozzle opening is to form a stable flow of the melt to obtain a uniform and continuous quenched ribbon. If the molten material were to fall directly onto the roll surface without passing through the nozzle orifice, only a non-uniform and discontinuous ribbon would be obtained. At this time, the molten substance and the nozzle come into contact, so reactions between the two become a problem, but the nozzle may be made of water-cooled metal, boron nitride, graphite, etc.
If the material is made of a high melting point material such as magnesium oxide, the contact time is extremely short, so almost no reaction occurs between the two. As described above, the Ta-W amorphous alloy described in claim 1 of the present invention can be easily produced by the manufacturing method described in claim 2. In addition, the liquid quenching method is usually carried out at a cooling roll surface speed of 50 m/sec or less, but by increasing this to 90 m/sec or more, the Ta-W alloy of the present invention can be It can be more easily amorphized. In order to rapidly solidify a molten alloy and make it amorphous, a higher quenching rate is more advantageous; however, increasing the peripheral speed of the rolls leads to a reduction in the thickness of the quenched ribbon. Therefore, it becomes easier to become amorphous. (Example) FIG. 1 shows an example of an apparatus for producing the Ta-W amorphous alloy of the present invention. In the figure, 1 is a water-cooled copper crucible, 2 is a raw material alloy, 3 is a boron nitride nozzle, 4 is a quenching roll, and 5 is a plasma torch. The crucible 1 is divided into left and right blocks, and can be opened and closed to the left and right by means of a rod 6. Therefore, the sample 2 is melted by plasma with the rod 6 pushed inside, and then
When the rod 6 is pulled outward, the crucible 1 opens left and right, and the sample 2 falls into the nozzle 3 by gravity. At that time, if gas is introduced into the upper chamber from the gas inlet 7 and the lower chamber is evacuated by the vacuum pump 8, the sample 2 will be moved through the nozzle due to the pressure difference between the upper and lower chambers. 3 onto the surface of the roll 4 to form a quenched ribbon. The hole diameter of the nozzle 3 was 0.5 mm to 1.0 mm. The roll 4 was made of copper and had a diameter of 250 mm, and was rotated at a speed of 8000 rpm. The circumferential speed is approximately 105 m/sec. Using this apparatus, a Ta-W-B alloy was liquid-quenched, and the structure of the obtained ribbon was investigated by X-ray diffraction. As a result, Ta and W are in total
In the composition range of 70 to 90 at%, no sharp diffraction peaks due to crystals were observed in any of the ribbons, and a broad halo pattern was obtained, confirming that the ribbons were in an amorphous phase. Next, Table 1 shows the crystallization temperatures of these samples measured by differential thermal analysis.
However, Sample Nos. 6, 12, and 18 in Table 1 are outside the scope of the present invention. It can be seen that all the samples exhibit a high crystallization temperature of 1000°C or higher, which is 50°C to 200°C higher than that of the Ta-Si-B amorphous alloy. Also, these samples
The amorphous structure was maintained even after annealing at 800°C for 1000 hours, indicating that the alloy is an extremely heat-resistant amorphous alloy. Furthermore, the mechanical properties of these samples show excellent properties with a Bitkers hardness ranging from 900 to 1600. Even if I left it for a day, I didn't see any signs of corrosion.
No change in weight was observed.

【table】

[Table] (Effects of the invention) As explained in detail above, in the present invention
The Ta-W amorphous alloy and its manufacturing method have a high crystallization temperature and can easily produce an amorphous alloy with excellent mechanical properties, corrosion resistance, etc., and the effects thereof are significant.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of an apparatus for producing the Ta-W based amorphous alloy of the present invention. In the figure,
1 is a water-cooled copper crucible, 2 is a raw material alloy, and 3 is a water-cooled copper crucible.
is a nozzle made of boron nitride, 4 is a rapid cooling roll, 5 is a nozzle made of boron nitride,
is a plasma torch, 6 is a rod for opening and closing the crucible, 7 is a gas inlet, and 8 is a vacuum pump.

Claims (1)

[Claims] Represented by the formula 1 (Ta1−xWx)yBz, where x=
A Ta-W based amorphous alloy characterized in that 0.01 to 0.8, y=0.7 to 0.9, and z=0.1 to 0.3. 2 (Ta1−xWx)yBz, x=
A raw material alloy having a composition of 0.01 to 0.8, y = 0.7 to 0.9, and z = 0.1 to 0.3 is melted in a water-cooled metal crucible, and the melted alloy is passed through a water-cooled metal nozzle or a high melting point material. The Ta- A method for producing a W-based amorphous alloy.