JPH0448860B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a Ta-W based 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 found in 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 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 limit is about 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.
(Unexamined Japanese Patent Publication No. 170450/1983). Furthermore, this Ta-Si-B ternary amorphous alloy is
Because it has excellent mechanical properties such as strength and high hardness unique to general amorphous alloys, for example,
Potential applications include wear-resistant materials, composite reinforcement materials for structural materials used at high temperatures, and materials for electrodes that are subject to elevated temperatures. However, when the Ta-Si-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 amorphous alloy and a method for manufacturing the same. (Means for Solving the Problems) The present invention is expressed by the formula (Ta _1-x W _x )y(Si _1-z B _z )u, where x=0.01 to 0.8, z=0.01 to 0.99. ,y
It is a Ta-W based amorphous alloy characterized by u = 0.7 to 0.9 and u = 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 heated in a water-cooled metal The molten alloy is melted in a crucible and is rapidly solidified by spraying it 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 becomes amorphous over time. 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) In Ta-W-Si-B alloy, Ta and W are 70at%
The present inventors have discovered for the first time that an amorphous alloy can be obtained in a composition range of ~90 at%. 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. Furthermore, the reason why the range of Z is limited to 0.01 to 0.99 is because 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 temperature of these amorphous alloys is between 1000°C and 1200°C, relative to their high melting points.
This is a high value. 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 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. 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,
Possible materials include silver, or alloys thereof, tungsten, molybdenum, etc. 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. 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, , because 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/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 crucible made of a shell, 2 is a raw material alloy, 3 is a nozzle made of boron nitride, 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, when the rod 6 is pushed inward and the sample 2 is melted by the plasma, and then the rod 6 is pulled outward, the crucible 1 opens left and right, and the sample 2 is moved by gravity into the nozzle. 3. At that time, if gas is introduced into the upper chamber from the gas inlet port 7 and the lower chamber is evacuated by the vacuum pump 8, the pressure difference between the upper and lower chambers will Then, the sample 2 is ejected from the nozzle 3 onto the surface of the roll 4 and becomes 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 800 rpm. The circumferential speed is approximately 105 m/sec. Using this apparatus, a Ta-W-Si-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 70~90at
% composition range, no sharp diffraction peaks due to crystals were observed in any of the ribbons, and a broad halo pattern was obtained, confirming that they were in an amorphous phase. Next, Table 1 shows the crystallization temperatures of these samples measured by differential analysis. However, samples Nos. 6, 12, and 24 in Table 1 are outside the scope of the present invention.

【table】

[Table] All samples show a high crystallization temperature of 1000°C or more, which is 100°C to 200°C higher than that of the Ta-Si-B amorphous alloy. I understand. Also, these samples were heated to 800℃
The alloy maintained its amorphous structure even after being annealed for 1000 hours, proving it to be an extremely heat-resistant amorphous alloy. Furthermore, the mechanical properties of these samples showed excellent properties with a Bitkers hardness ranging from 900 to 1600, and these samples were also exposed to concentrated hydrochloric acid, concentrated nitric acid, concentrated sulfuric acid, and concentrated aqua regia. Even after being left inside for a day, no signs of corrosion were observed, and no change in weight was observed. (Effect of the invention) As explained in detail above, 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 (Ta _1-x W _x )y (Si _1-z B _z )u, where x=0.01-0.8, z=0.01-0.99, y=0.7-
0.9, Ta- characterized by u=0.1~0.3
W-based amorphous alloy. 2 (Ta _1-x W _x )y (Si _1-z B _z )u, x=0.01~0.8, z=0.01~0.99, y=0.7~
A raw material alloy having a composition of 0.9, u = 0.1 to 0.3 is melted in a water-cooled metal crucible, and the melted alloy is transferred using a water-cooled metal nozzle or a nozzle made of a high melting point material. , a Ta-W based amorphous alloy characterized by being made amorphous by being injected onto the surface of a cooling roll rotating at high speed at a surface circumferential speed of 90 m/sec or more and rapidly solidifying it. manufacturing method.