JPS6362837A - Ta-w amorphous alloy and its production - Google Patents

Abstract

PURPOSE:To easily manufacture an amorphous alloy having high crystallization temp. and combining high strength with high corrosion resistance, by spraying a molten alloy having a specific composition consisting of Ta, W, Si, and B onto the surface of a rapidly rotating roll by the use of a nozzle so as to carry out rapid cooling. CONSTITUTION:The alloy 2 as raw material represented by a formula (Ta1-xWx)y(Si1-zBz)u [where the symbols (x), (z), (y), and (u) stand for 0.01-1, 0.01-0.99, 0.7-0.9, and 0.1-0.3, respectively] is put into a water-cooled copper crucible 1 and melted by means of plasma by the use of a plasma torch 5. Subsequently, rods 6 are pulled right and left to open the crucible 1, by which the molten alloy in the crucible 1 is dropped into a water-cooled nozzle 3 made of metal or high-m.p. material such as BN, etc. At this time, a gas is introduced into the upper chamber from a gas- introducing hole 7 and the lower chamber is evacuated by means of a vacuum pump, so that above-mentioned molten alloy is sprayed through the nozzle 3 onto the surface of a rapidly rotating cooling roll 4 by means of a difference in pressure between both chambers. It is preferable that surface speed of the above roll 4 is regulated to >=90m/sec. In this way, the above molten alloy is subjected to rapid solidification, so that Ta-W amorphous alloy can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application!'?) The present invention relates to a Ta--W 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. These alloys are metals that do not have a crystal structure, unlike conventional crystalline alloys, and many of their properties are not the same as those of conventional metal materials, such as mechanical properties, abrasion resistance, corrosion resistance, and softness. Due to its excellent magnetism, various uses are being developed as a material that can replace crystalline metals, 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 original characteristics are lost. This crystallization temperature varies depending on the material, but is generally 0.4 to 0.0% of the melting point measured in absolute temperature.
It is known that the value is about 6 times higher.

Therefore, in order to obtain an amorphous alloy with a high crystallization temperature,
Alloys with high melting points must be made amorphous by a method such as liquid quenching.

However, most conventional liquid quenching devices are made for materials with relatively low melting points, such as iron-based alloys. Most of them are. Therefore, the maximum operating temperature is limited by the fire resistance of the nozzle material, and is limited to about 1200 to 1400°C. 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-8i-B ternary amorphous alloy, which has an extremely high melting point of about 2400°C, has a crystallization temperature of 800°C to 960°C, which makes it a very high crystallization temperature for amorphous alloys. It became possible to significantly improve the problem. (Tokugan Sho 6
1゜012385).

Furthermore, this Ta-8i-B ternary amorphous alloy has excellent mechanical properties such as high strength and high hardness that are characteristic of general amorphous alloys, so it has excellent mechanical properties such as high strength and high hardness. abrasive materials,
Potential applications include composite reinforcing materials for structural materials used in high-frequency sounds, and materials for electrodes that are subject to temperature increases.

However, when the Ta-8i-B-based amorphous alloy is actually used in a high-temperature environment, aging becomes a problem, so the operating temperature range is limited to a maximum of about 6006C.

The present invention solves the problems of the prior art, has a high crystallization temperature, can withstand a higher temperature environment than the Ta-based amorphous alloy, and has excellent mechanical properties, corrosion resistance, etc. An object of the present invention is to provide an excellent amorphous alloy and a method for producing the same.

(Means for solving the problems) The present invention provides (Tax-xWx)y(Sil-zBz)u
It is expressed by the formula, where x=0.01 to 1. z=0.0
1-0.99. y=0.7-0.9. u=0-1~0.
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 Melting the alloy in a crucible and 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, characterized in that the Ta--W amorphous alloy is made amorphous by being injected onto the surface of a cooling roll rotating at high speed and rapidly solidified. Further, in this case, it is more preferable as a manufacturing method if the surface circumferential speed of the cooling roll is 90 m/sec.

(Function) The present inventors have discovered for the first time that in a Ta-W-8i-B alloy, an amorphous alloy can be obtained in a composition range of Ta and W or W in a range of 70 at% to 90 at%. When the composition is outside this range, the amorphous structure becomes almost invisible, 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.

Further, the reason why the range of X is limited to 0.01 or more is because the crystallization temperature becomes higher when W is added than when Ta is added alone. Furthermore, set the range of X to 0,01~0
．． The reason why it is limited to 99 is that in this range, the crystallization temperature becomes higher than when a trace amount of Si or B is added, or when only one of them is added. The crystallization temperatures of these amorphous alloys correspond to their high melting points,
This is a high value of 1000°C to 1200°C. The mechanical properties of these amorphous alloys are high strength and hardness, as is typical of amorphous alloys. Furthermore, in terms of corrosion resistance, it has corrosion resistance comparable to that of Ta or 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. If the crucible metal is water cooled,
This is because even if high-temperature molten metal comes into contact, the temperature of the crucible metal is too low 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, or their alloys, or tungsten, molybdenum, etc. may be considered.

In addition, melting methods include arc melting, plasma melting,
Well known methods such as electron beam melting, laser beam melting, etc. 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.

Also, since the molten substance and the nozzle come into contact at this time, reactions between the two become a problem, but if the nozzle is made of water-cooled metal or a high melting point material such as boron nitride, graphite, or magnesium oxide, Since the contact time is extremely short, 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/see or less;
/see or more, the Ta--W alloy of the present invention can be made more easily amorphous. 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 socket 6.

Therefore, if the sample 2 is melted by plasma with the tip 6 pushed inward, and then the tip 6 is pulled outward,
The crucible 1 opens left and right, and the sample 2 falls into the nozzle 3 due to gravity. At that time, if gas is introduced into the upper chamber in advance from the gas introduction lower and the lower chamber is evacuated by the vacuum pump 8, the sample 2 will be transferred from the nozzle 3 to the surface of the roll 4 due to the pressure difference between the upper and lower chambers. It erupts upwards and becomes a quenched ribbon. The hole diameter of nozzle 3 is 0.5m
m 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/see.

Using this apparatus, a Ta-W-8i-B alloy was liquid-quenched, and the structure of the obtained ribbon was investigated by X-ray diffraction. As a result, in the composition range of Ta and W, or 70 to 90 at% W, no sharp diffraction peaks due to crystals were observed in any of the ribbons, and a broad halo pattern was obtained, indicating that the ribbons are in an amorphous phase. This was confirmed. Next, Table 1 shows that all the samples in Table 1 measured by differential analysis show a high crystallization temperature of 1000°C or more, which is even higher than that of the Ta-8i-B amorphous alloy. It can be seen that the crystallization temperature is ~200°C higher. Also, these samples were heated to 1 at 800°C.
It was found that the amorphous alloy maintained its amorphous structure even after being annealed for 0,000 hours, and was an amorphous alloy with extremely high heat resistance. Furthermore, the mechanical properties of these samples show excellent properties with Vickers hardness ranging from 900 to 1600. Even after being left inside for a day, no signs of corrosion were observed, and no change in weight was observed.

(Effects of the Invention) As explained in detail above, the Ta-W amorphous alloy and the method for producing the same in the present invention have a high crystallization temperature,
In addition, an amorphous alloy with excellent mechanical properties, corrosion resistance, etc. can be easily obtained, and its effects are significant.

[Brief explanation of drawings]

FIG. 1 is a diagram showing 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 rapid cooling roll, 5 is a plasma torch, 6 is a rod for opening and closing the crucible, and 7 is a gas introduction Port 8 is a vacuum pump. E 1 Figure

Claims (3)

[Claims] (1) (Ta_1_-_xW_x)y(Si_1_-_
It is expressed by the formula zB_z)u, where x=0.01 to 1, z
=0.01-0.99, y=0.7-0.9, u=0.
1 to 0.3. (2) (Ta_1_-_xW_x)y(Si_1_-_
It is expressed by the formula zB_z)u, where x=0.01 to 1, z
=0.01-0.99, y=0.7-0.9, u=0.
A raw material alloy having a composition of 1 to 0.3 is melted in a water-cooled metal crucible, and the melted alloy is heated at high speed using a water-cooled metal nozzle or a nozzle made of a high-melting point material. A method for producing a Ta-W based amorphous alloy, which comprises making the Ta-W amorphous alloy amorphous by injecting it onto the surface of a rotating cooling roll and rapidly solidifying it. (3) The T according to claim 2, wherein the surface circumferential speed of the cooling roll is 90 m/sec or more.
A method for producing an a-W amorphous alloy.