JPH02302392A - Method for controlling solidified texture of metal and apparatus therefor - Google Patents

Abstract

PURPOSE:To enable the control of especially the temperature gradient of a coagulation interface over a wide range and obtain a metal having unidirectionally solidified texture by encircling a vertical ceramic cylinder with a high-frequency induction coil for heating, vertically shifting the ceramic cylinder relative to the coil and supplying a melting raw material into the cylinder. CONSTITUTION:A melting raw material 4 consisting of a metallic rod having circular or polygonal cross-section is clamped 5, set at a specific position and melted by heating with a high-frequency induction coil 3 while lowering 10 the receiving table 2. During the above process, the temperature gradient is made to be sufficiently large to prevent the super-cooling of texture at the coagulation interface contacting with the molten zone 6 and the temperature gradient is controlled in such a manner as to keep the coagulation interface to be upwards convex. A unidirectional excellent solidified texture can be formed by this process. A metallic rod having unidirectionally solidified texture with extremely excellent directionality can be produced in high energy effect.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention melts and solidifies a rod-shaped metal body made of pure metal or various alloys, controls the solidification structure, and obtains a unidirectional solidification structure or single crystal structure. The present invention relates to an apparatus and apparatus for controlling the solidification structure of a metal body.

[Prior art] An apparatus for manufacturing metal bodies with a controlled solidification structure was developed by the Japanese Patent Publication No. 1986-5.
This method has been proposed in JP-A No. 7418, Japanese Unexamined Patent Application Publication No. 62-227551, and the like.

Japanese Patent Publication No. 62-57418 discloses a method in which metal melted in a crucible is sequentially solidified and pulled upward, while Japanese Patent Publication No. 62-227551 discloses a method in which metal melted in a crucible is pulled upward through an opening provided in the side wall of the crucible. This method involves sequentially pulling out horizontally from the beginning.

[Problem to be solved by the invention] In both of these methods, the entire amount of the melted material is melted,
This method involves sequentially solidifying the molten metal while drawing it out, which requires preparing a large amount of molten metal and holding it while controlling the temperature, which has many disadvantages in terms of energy efficiency.

In both cases, the mold heating method for controlling the solidification structure is simple resistance heating or high frequency heating using a multi-wound coil. Therefore, the control element for the temperature gradient at the solidification interface, which is most important for controlling the solidification structure, is limited. Although it is possible to forcibly cool the solidified metal body with water or other gas, metals that are highly susceptible to cracking, such as intermetallic compounds, will cause cracks in the metal body, making it impossible to obtain a good metal body.

As described above, it is often difficult to obtain a metal body with a well-controlled solidification structure using conventional methods or devices.

In order to obtain a metal body with a so-called unidirectional solidification structure in which the solidification structure of the metal body is controlled in one direction, the present invention particularly aims to control the temperature gradient at the solidification interface over a wide range and to have a good unidirectional solidification structure. An object of the present invention is to provide an apparatus for manufacturing a metal body having one of the following.

Here, the metal body is a pure metal such as Affl, Cu, or Ti.

For metals, including but not limited to Fe, SL, alloys, and intermetallic compounds thereof, unidirectional solidification structures or single crystal structures can be obtained by solidifying in one direction from below or above. can get.

[Means for Solving the Problems] The apparatus for controlling the solidification structure of a metal body according to the first invention comprises: a ceramic cylinder is vertically erected on a pedestal, and a high-frequency induction coil for heating is arranged surrounding the ceramic cylinder. , a mechanism for relatively moving the high-frequency induction coil or the ceramic cylinder upward or downward, and a mechanism for supplying the melted material into the ceramic cylinder.

The solidification structure control method of a metal body according to the second invention uses the solidification structure control device according to the first invention to control high-frequency induction power, dissolution rate, and solidification rate, so as to control the solidification interface at the center of the solidified metal body. It is characterized by performing melting and solidification while controlling it so that it becomes convex upward.

[Example] The basic configuration of the present invention will be explained with reference to the drawings.

FIG. 1 is a diagram showing a solidification structure control device for a metal body according to an embodiment of the present invention, in which a pedestal 2, usually made of ceramic, is arranged at the center of the striations and the solidification structure control device for a metal body. A ceramic cylinder 1 is placed. The ceramic cylinder 1 has a low melting point A
When dissolving II, Cu, etc., for example, silica (SiO
z), but if it is made of Fe etc. with a high melting point,
Alumina (Aρ2OS), pyrolytic boron nitride (
The ceramic cylinder 1 is preferably made of ceramic such as P-BN>.
A high-frequency coil 3 is arranged to supply high-frequency power from the outside!
do. The structure of this high-frequency coil 3 is preferably a flat plate in order to locally input electric power to the melted material 4.
is suspended by a melted material support chuck 5 that holds it at the upper part. This melted material support chuck 5 rotates coaxially with the melted material as necessary. This rotation has the effect of making the melting surface of the melting material 4 uniform and also making the temperature distribution in the melting zone 6 uniform, contributing to structure control.

In order to locally concentrate the high-frequency power in the melting zone 6, a flat high-frequency coil is suitable, and examples of its structure are shown in FIGS. 2 and 3. FIG. 2(a) is a perspective view of a flat high-frequency coil according to an embodiment of the present invention, and FIG. 2(b) is a perspective view of a flat high-frequency coil according to an embodiment of the present invention.
[It is an AA sectional view of g(a). Reference numeral 7 denotes a first magnetism collecting ring made of a copper disk, and the inside thereof forms a bank 71 through which a cooling medium, for example, water, flows, and as a whole prevents the dispersion of magnetic lines of force generated by the high-frequency coil 3, which is usually water-cooled. do. FIG. 2 is an example of preventing the magnetic lines of force from dispersing upward in a high-frequency coil. An insulator 72 is inserted between the first magnetism collecting ring 7 made of copper and the high frequency coil 3.

FIG. 3 is a diagram showing a flat high frequency coil according to another embodiment, FIG. 3(a) is a perspective view of a flat high frequency coil according to another embodiment of the present invention, and FIG. 3(b) is a diagram showing a flat high frequency coil according to another embodiment of the present invention. is B in Figure 3 (a>
-8 sectional view. This figure shows the high frequency coil 3 formed integrally with the first magnetism collecting ring made of copper, and the water cooling connection part 31.
Cooling water is supplied and drained from the pipe, and it is connected to a water cooling pipe 32.

These high frequency coils 3 are normally designed for heating purposes.

The high frequency coil 3 shown in FIG.
It is possible to prevent the magnetic lines of force from dispersing upward. This is to concentrate the lines of magnetic force on the melt 6. Further, a second magnetic flux collecting ring 70 is provided below the high-frequency coil 3 at a position where the temperature gradient at the solidification interface is optimal for a unidirectionally solidified structure. The farther the second magnetic flux collecting ring 70 is from the high frequency coil 3, the more the magnetic lines of force are absorbed in the solidified portion and the more heat is generated. Therefore, by adjusting the distance between the second magnetic flux collecting ring 70 and the high frequency coil, The temperature gradient at the solidification interface can be adjusted.

Using the first magnetic flux collecting ring and the second magnetic flux collecting ring,
This controls the temperature gradient at the solidification interface of the molten zone 6 and ultimately controls the crystal orientation.

Furthermore, the melting speed is controlled while controlling the supply speed of the melting material 4, input power, etc., and melting and solidification are completed. When the high frequency coil 3 is in the fixed position, the pedestal 2 is lowered. When the ceramic cylinder 1 is made of transparent quartz or pyrolytic boron nitride (P-BN) that transmits infrared rays, a television camera or an infrared camera 9 is arranged to observe the melting zone, and the dissolution rate is controlled while observing. You can also do that. The pedestal 2 is connected to a lowering mechanism 10 that lowers the solidified metal body 8. On the other hand, fix the cradle 2,
Of course, it is also conceivable that melting is carried out while moving the high frequency coil 3, the first magnetic flux collecting ring 7, and the second magnetic flux collecting ring 70 upward.

If the metal body 8 to be melted is easily oxidized in the atmosphere, for example, pure iron, the entire apparatus shown in FIG. 1 is housed in a closed container such as a ceramic container made of transparent quartz or a metal container. However, it is preferable to melt and solidify the container by filling it with an inert gas or the like.This hermetic container is constructed entirely of a metal container instead of the transparent quartz, and a part is provided with a window for internal observation. It is practical to provide a filter and construct it from glass, quartz, or the like. - The ceramic cylinder 1 shown in Fig. 1 has a bottom, and the case where melting and solidification were performed while moving either the high-frequency coil 3 or the metal body 8 relatively was shown, but as will be explained next. There are other implementations as well. That is, as shown in FIG. 4, a ceramic cylinder 1 is formed with open upper and lower ends, and when melting and solidification is started, a part of the pedestal 2 is cut and melted as shown in FIG. 4(b). Solidified metal body 8
It is also possible to lower the pedestal 2 by the lowering mechanism 10 after forming the cradle.

FIG. 4(a) shows the steady state in this embodiment, and FIG. 4(b) shows the state at the start of production.Other points are the same as in FIG. 1.This device Then, the ceramic cylinder l is placed in a fixed position, the molten material 4 is continuously or semi-continuously supplied from above, and the metal body 8 that has completed melting and solidification is continuously or semi-continuously drawn downward. The objective is achieved by, where the high-frequency coil 3 remains in place and therefore the melting zone 6 also remains in place.

Here, the operating method and operation of this coagulation structure control device will be explained. First, a commercially available circular or polygonal rod-shaped metal body is prepared as the melting material 4. Aβ,
Cu, Fe, or their alloys only need to be formed into a rod shape. In the case of metals that are difficult to process, a rod-shaped material made by compression molding of powder is preferable. This is held by the material support chuck 5 and held in a predetermined position. After setting, for example, the pedestal 2 is lowered by lowering 81 and horizontal 10 while being melted by high-frequency power. The important points here, as shown in Figures 4(a) and (b), are: 1) having a sufficient temperature gradient to prevent systematic cooling at the lower solidification interface; 2) It is necessary to control the temperature distribution so that the solidification interface is convex upward in one direction and to obtain a good solidification structure. Condition (2) is such that no equiaxed crystals are generated in the molten metal at the solidification interface, and therefore the crystals always advance upward from the solidification interface. This condition differs depending on the type of metal. Condition (2) is a condition in which the solidification interface is always above and solidifies from the inside of the metal body toward the outer periphery when observed on the same plane, and as a result, solidification shrinkage holes do not occur inside the metal body, and normal ingots are solidified. This is an important requirement to prevent the central segregation observed in The above conditions are controlled by the high frequency coil shape, the melting speed, the reciprocal movement speed, and also the rotational speed of the melted material. Generally, when high-frequency power is input from the external high-frequency coil 3, a large amount of power is input to the outer periphery of the metal body (skin effect), and the input power decreases as it goes inside, so this device is extremely convenient.

Since it has more control elements than the conventional apparatus described above, it plays a very important role in producing a metal body having a unidirectionally solidified structure. Fig. 4 shows that, as mentioned above, a short ceramic cylinder with an open bottom is used, and the molten material is supplied continuously or semi-continuously from above, and the melted and solidified metal body can be produced continuously or semi-continuously. different. FIG. 4(b) shows the mechanism of this apparatus at the time of starting production. That is, a part of the pedestal 2 is cut, for example, as shown in the figure, and after a predetermined period of time, the pedestal 2 is lowered by the lowering mechanism 10 to perform melting and solidification. An example will be explained.

(Example 1) Ar gas was sealed in a sealed quartz container with an outer diameter of 250 mm and a length of 1500 mm, and the apparatus shown in FIG. 1 was set inside the container. A quartz crucible ceramic cylinder 1 with an inner diameter of 50 m Φ and an outer diameter of 54 Φ is placed on a pedestal 2, and an outer diameter of 40111 Φ is placed.
, 99.99% purity A! ! Melting and solidifying a metal rod,
Pulled out at 5-15 m*/via. Obtained A
The I metal body is approximately 49 Φ and 400 as long. Only three crystals were observed in the cross section of the metal body 8, and each crystal was oriented from the bottom to the top and had a completely unidirectional solidification structure.

In the above, when we compared the case where the melted material 4 was rotated 10 times per minute and the case where it was not rotated at all, we found that when it was rotated, the number of crystals in the cross section was not different, but the directionality was better. . This kind of pure A1 metal body processed into a wire rod with a diameter of 1 to 2 Φ had particularly excellent electrical characteristics. In the above experiment, a high frequency power of 200 KHz was applied at a maximum of 13 KW*.

(Example 2) Instead of the quartz crucible used in Example 1, a ceramic cylinder 1 made of pyrolytic boron nitride (P-BN) was arranged as shown in FIG. 4. As described above, FIG. 4(b) shows the state where the melting-solidification operation is started. In this case, the ceramic cylinder 1 of pyrolyzed boron nitride (PB, N)
The inner diameter is 50 mm and the outer diameter is 54 mm. The melting material is A & metal rod with a purity of 99.99% and a diameter of 45 mm. The melted and solidified metal body has a diameter of approximately 49 maΦ,
The length was 500mm. The properties of this metal body were also the same as in Example 1, and the electrical properties were excellent. In this experiment, the experiment was conducted while observing the molten zone with an infrared camera.

[Effects of the Invention] The method and apparatus of the present invention sequentially melt and solidify the melted material through the relative movement of the high-frequency induction coil and the melted material, and control the melting rate and cooling method, so it is highly energy efficient. A rod-shaped metal body having a unidirectional solidification structure with excellent directionality could be manufactured. Since the crystal orientation of this rod-shaped metal body is controlled in one direction, it has excellent mechanical and electrical properties.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of a solidification structure control device for a metal body according to an embodiment of the present invention, FIGS. 2 and 3 are diagrams showing different high-frequency coils of this embodiment, and FIG. 4 is a ceramic with an open bottom. FIG. 3 is a longitudinal cross-sectional view showing the configuration of the device when a cylinder is used. DESCRIPTION OF SYMBOLS 1... Ceramic cylinder, 2... Pedestal, 3... High frequency coil, 4... Melting material, 5... Material support chuck, 6... Melting zone, 7... First Magnetism collecting ring, 8.
...Metal body, 9...TV camera or infrared camera,
10... Lowering mechanism, 70... Second magnetism collecting ring, 7
DESCRIPTION OF SYMBOLS 1... Water cooling groove, 72... Insulator, 31... Water cooling connection part, 32... Water cooling groove.

Claims (5)

[Claims] (1) A mechanism is provided in which a ceramic cylinder is placed vertically on a pedestal, a high-frequency induction coil for heating is placed surrounding the ceramic cylinder, and the high-frequency induction coil or the ceramic cylinder is relatively moved upward or downward. 1. A solidification structure control device for a metal body, comprising: a mechanism for supplying a melted material into the ceramic cylinder. (2) A solidification structure control device for a metal body, characterized in that the entire solidification structure control device for a metal body according to claim 1 is housed in a metal container or a ceramic container. (3) A solidification structure control device for a metal body according to claim 2, wherein the ceramic container is made of transparent quartz. (4) In the solidification structure control device according to any one of claims 1, 2 and 3, the metal body is equipped with a television camera or an infrared camera for observing the metal dissolution zone or measuring the temperature. Coagulation tissue control device. (5) Using the solidification structure control device according to any one of claims 1, 2, 3, and 4, the solidification interface of the center of the solidified metal body is controlled by controlling the high frequency induction power, the dissolution rate, and the solidification rate. A method for controlling the solidification structure of a metal body, characterized by performing melting and solidification while controlling the metal body to be convex upward.