JPS6362838A - 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, and B onto the surface of a rapidly rotating roll through a water-cooled nozzle so as to carry out rapid solidification. CONSTITUTION:The alloy 2 as raw material represented by a formula (Ta1-xWx)yBz [where the symbols (x), (y) and (z) stand for 0.01-1, 0.7-0.9, and 0.1-0.3, respectively] is melted in a water-cooled metallic crucible 1 by means of plasma from a plasma torch 5. Subsequently, rods 6 are pulled right and left to open the crucible 1, so that molten alloy 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 previously introduced from a gas- introducing hole 7 into the upper chamber and also the lower chamber is evacuated by means of a vacuum pump 8. By using the resulting difference in pressure between both chambers, the above molten alloy is sprayed through the nozzle 3 onto the surface of a cooling roll 4 made of copper, etc., rapidly rotating at a surface speed of >=90m/sec to undergo rapid solidification. In this way, a Ta-W amorphous alloy excellent in mechanical properties, corrosion resistance, etc., and having high crystallization temp. can be obtained.

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 of its excellent properties, 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 0.6 of the melting point measured in absolute temperature.
It is known that the value is about twice as high. 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 in which a heat-resistant nozzle made of quartz or other material is heated by resistance heating or high-frequency energy. 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. Also,
The types of alloys that can be rapidly cooled have been limited, as the nozzle material and the alloy may react with each other as the temperature rises, potentially causing contamination of the powder.

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 8006°C to 960°C, which is a problem with amorphous alloys. It has become possible to significantly improve the (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. , e.g. wear-resistant materials,
Potential applications include composite reinforcing materials for structural materials used at high temperatures and materials for electrodes that are subject to temperature increases.

However, when the Ta-8i-B 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 600°C. .

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 producing the same.

(Means for solving the problem) The present invention is expressed by the formula (Tal-xWx)yBz,
x=0.01~1. y=0.7-0.9. z＝
It is a Ta-W based amorphous alloy characterized by having a molecular weight of 0.1 to 0.3. 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 placed in a water-cooled metal crucible. The molten alloy is rapidly solidified by being 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. This is a method for producing a Ta-W based amorphous alloy, which is characterized in that it undergoes crystallization.

In addition, at this time, the surface peripheral speed of the cooling roll is 90 m/
sec, it is more preferable as a manufacturing method.

(Function) In Ta-W-B alloys, as shown in Examples later, T
The present inventors have discovered that an amorphous alloy can be obtained in a composition range in which a and W are in the range of 70 at% to 90 at% in total. 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.

Furthermore, 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. The crystallization temperatures of these amorphous alloys range from 1000°C to 120°C, corresponding to their high melting points.
This is a high value of 0°C. The mechanical properties of these amorphous alloys are high strength and hardness, as is commonly found in amorphous alloys. In addition, in terms of corrosion resistance, Ta
and has corrosion resistance comparable to that of 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, 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.

In addition, 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, the contact time is is so short that 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 peripheral speed of 50 m/sec or less;
By making it more than e, the Ta-W alloy of the present invention can be made amorphous more easily.

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 using a rod 6.

Therefore, if the sample 2 is melted by plasma with the rod 6 pushed inward, and then the rod 6 is pulled outward,
The crucible 1 opens left and right, and the sample 2 falls into the nozzle 3 by force. At that time, if gas is introduced into the upper chamber 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 roll 4 due to the pressure difference between the upper and lower chambers. It erupts onto the surface and becomes a quenched ribbon. The hole diameter of nozzle 3 is 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/see.

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, in the composition range of 70 to 90 at% of Ta and W in total, 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 were in an amorphous phase. was confirmed. Next, Table 1 shows the crystallization temperatures of these samples measured by differential thermal analysis. All samples show a high crystallization temperature of 1000°C or more, which indicates that the crystallization temperature is 506C to 200°C higher than that of the Ta-8i-B amorphous alloy. . Furthermore, these samples maintained their amorphous structure even after being annealed at 800°C for 1000 hours.
It turned out to be an amorphous alloy with extremely high heat resistance.

Furthermore, the mechanical properties of these samples are excellent, with Vickers hardness ranging from 900 to 1600. Even after being left for a day, no signs of corrosion were observed, and no change in weight was observed.

m-・.

Table 1 (Effects of the Invention) As explained in detail above, the Ta-W amorphous alloy of the present invention and its manufacturing method 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 well. 1 figure

Claims (3)

[Claims] (1) It is expressed by the formula (Ta1-xWx)yBz, and x
=0.01~1, y=0.7~0.9, z=0.1~0
．． 3. An amorphous alloy characterized by: (2) It is expressed by the formula (Ta1-xWx)yBz, and x
=0.01~1, y=0.7~0.9, z=0.1~0
．． A raw material alloy having a composition of 3 is melted in a water-cooled metal crucible, and the molten alloy is cooled using a water-cooled metal nozzle or a nozzle made of a high melting point material, which is rotating at high speed. A method for producing a Ta--W amorphous alloy, characterized in that it is made amorphous by being injected onto the surface of a roll and rapidly solidified. (3) The method for producing a Ta-W amorphous alloy according to claim 2, wherein the surface circumferential speed of the cooling roll is 90 m/sec or more.