JPH04108698A - Growing device for single crystal of fe-si-al-based alloy - Google Patents

Abstract

PURPOSE:To uniform composition and to enhance the magnetic characteristics and the mechanical characteristics by locally heating a raw material for polycrystal of Fe-Si-Al-based alloy held in a crucible and preventing this heat from being discharged exclusive of the heating part. CONSTITUTION:After a raw material 2 for polycrystal of Fe-Si-Al-based alloy is held in a crucible 5 and the inside of a furnace 4 is regulated to the vacuum atmosphere by a rotary pump 13, inert gas or reductive gas is supplied from a gas cylinder 12 and the inside of the furnace 4 is pressurized. Then, high-frequency current is allowed to flow to a high-frequency heating coil 19. A carbon susceptor 25 is provided in a heat insulated box 9 arranged in a heating mechanism 6 and heated. This heat is transferred to the raw material 2 via the crucible 5 and one part of the raw material 2 is melted. A melted part 26 is formed in the vicinity of the joining part of the raw material 2 and seed crystal 3. Then the crucible 5 is lowered in the direction shown in an arrow B by driving a driving part 10 which rotates, raises and lowers the raw material of the upper part. The melted part 26 is relatively moved to the upper part. Single crystal of Fe-Si-Al-based alloy is grown by cooling the part being in the position lower than the arranged position of the heat insulated box 9.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an apparatus for growing Fe-5t-Al alloy single crystals, and particularly to a Fe-Si-
The present invention relates to an apparatus for growing Al-based alloy single crystals.

[Conventional technology]

Single crystal Fe-Si-Al alloy (hereinafter referred to as Sendust) is an alloy with extremely high magnetic permeability and high hardness, and is used in audio magnetic heads and video tape recorders (VTRs). It is also used as a material for magnetic heads for rotary digital audio recorders (R-DAT).

However, when polycrystalline sendust is used as a magnetic head material, variations in the magnetic force applied to the magnetic tape may occur due to the plane orientation of the crystal grains that exist when forming the gap in the magnetic head, or due to the presence of crystal grain boundaries. According to
It is known that the mutual bond strength is weakened and the mechanical strength is weak, resulting in problems such as chipping, chipping, and cracking during grinding and cutting.

On the other hand, Sendust's single crystal has strong mechanical strength because there are no grain boundaries, and by selecting a specific plane orientation, the variation in magnetic force to the magnetic tape is reduced, improving wear resistance. The thing is known.

[Invention or problem to be solved]

However, it is difficult to grow single crystals of sendust with good properties, and conventional growth equipment is unable to grow the single crystals sufficiently, resulting in large segregation in the alloy composition. was there. .

In other words, in the commonly used Bridgman method for growing sendust, the entire sample in the crucible is melted once in a non-oxidizing atmosphere and then gradually cooled, so the melting range of sendust polycrystals is wide. Due to the difference in density between the raw materials constituting sendust, heavier raw materials precipitate more at the bottom of the molten metal, and conversely, lighter raw materials precipitate more at the top. Therefore, in the conventional growth apparatus, large segregation occurs in the alloy composition. If this segregation occurs, the magnetic properties of sendust will deteriorate significantly,
This makes it impossible to use it as a magnetic head material.

The present invention has been made in view of the above points, and an object of the present invention is to provide an apparatus for growing a Fe-Si-Al alloy single crystal that can effectively prevent the occurrence of segregation.

[Means to solve the problem]

In order to solve the above problems, in the present invention, Fe-Si
- Heating a crucible containing a polycrystalline sample of an Al-based alloy using a heating means to melt the polycrystalline sample, and moving the heating means and the polycrystalline sample relative to each other in the longitudinal direction of the polycrystalline sample. In the Fe-Si-Al alloy single crystal growth apparatus for growing a Fe-Si-Al alloy single crystal by It is characterized by being provided with a heat application mechanism that applies heat locally and prevents heat from being released to the outside.

[Effect]

According to the Fe-Si-Al alloy single crystal growth apparatus configured as described above, the heat of the heating means is locally applied to the crucible by the heat application mechanism. Furthermore, the applied heat is prevented from being released to areas other than this locally heated portion.

Therefore, the range in which the polycrystalline sample of the Fe-Si-Al alloy is melted is narrowed, segregation caused by the density difference of the raw materials is prevented, and Fe-Si having a uniform composition throughout is melted.
-Al-based alloy single crystals can be grown.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings. 1st
The figure is a diagram showing the main parts of a Fe-Si-Al alloy single crystal growth apparatus 1 (hereinafter simply referred to as the apparatus), which is an embodiment of the present invention. A round bar sample 2 which is a polycrystalline Sendust and a seed crystal 3 of Sendust are attached to the apparatus 1 shown in the figure, and a single crystal of Sendust is grown by the process described below.

The apparatus 1 includes a crucible 5, a heating mechanism 6, an upper chuck 7, a lower chuck 8, a heat insulating box (heat application mechanism) 9, which is a feature of the present invention, and the like, and an upper part outside. Sample rotation vertical drive unit 10, lower sample rotation vertical drive unit 11
, gas cylinder 12, rotary pump 13, pressure gauge 14,
A power source 15, a cooling pipe 16, etc. are provided.

The crucible 5 is made of ceramic, and has a seed crystal mounting part 5b in which the seed crystal 3 is mounted at the bottom of a conical part 5a in which the sample 2 is stored. In this crucible 5, the polycrystalline round rod sample 2 is melted, and the seed crystal 3 grows single crystal sendust.

As shown in an enlarged view in FIG. 2, the heating mechanism 6
7, a carbon susceptor z8, a high frequency heating coil 19, etc. The heat insulating box 17 is a cylindrical member made of ceramic (alumina), and a carbon susceptor I8 and an insulating tube 2 are disposed therein. This carbon susceptor 18 is provided so that the sample is not directly heated by the high frequency heating coil I9. Further, a heat insulating box 9, which is a main part of the present invention, is integrally disposed in the heating mechanism 6. The heating mechanism 6 having the above configuration is located at the bottom of the furnace 4.
It is held in contact with the Note that the heat insulation box 9 will be described in detail later.

The high-frequency heating coil 19 is connected to a heat-insulating box 9 on the outer periphery of the heat-insulating cylinder 17.
The power source 15 is located near the power source 15, and is connected to the power source 15. This high-frequency heating coil 19 heats the carbon susceptor 20 installed inside the heat insulation wi 9 using a high-frequency current supplied from the power source 15.

The crucible 5 is attached to the upper chuck 7 using a molybdenum wire 21. Further, the upper chuck 7 is attached to the furnace 4
It is connected to an upper sample rotation vertical drive section 10 disposed above the sample. This upper sample rotating vertical drive unit IO drives the upper chuck 7 to move the crucible 5 as indicated by the arrow B in the figure.
The crucible 5 is moved in the direction indicated by (downward), and the crucible 5 is rotated.

The gas cylinder 12 is for supplying an inert gas such as Ar or a reducing gas into the class 4, and the rotary pump 13 is for supplying an inert gas such as Ar or a reducing gas.
The pressure gauge 14 measures the pressure inside Class 4, and the cooling pipe 16 is installed around the outer circumference of the furnace 4 to cool the outside of the furnace 4 with water flow. It is.

Next, we will mainly discuss the second aspect of the heat retention wi9, which is the main part of the present invention.
This will be explained using figures.

The heat insulation box 9 is arranged in the heating mechanism 6 as described above.

This heat insulation box 9 forms one room in the heat insulation 11#17 by providing an upper lid 22 and a lower M23 made of ceramic. Further, insertion holes 22a and 23a are formed in the center of the upper lid 22 and the lower lid 23, respectively, so that the crucible 5 can be inserted thereinto. In addition, carbon felt 24 (shown in satin finish) is attached to the inner wall of the heat insulation box 9.
is installed. This carbon felt 24 functions as a heat insulating material.

Further, a carbon susceptor 25 is disposed inside the carbon felt 24 at a position facing the crucible 5. As mentioned above, the high frequency heating coil 19 is disposed near the outer periphery of the heat insulating box 9.
The carbon susceptor 25 is heated by supplying a high frequency current to the carbon susceptor 9 . The heat generated by the carbon susceptor 25 is applied to the crucible 5, and the sample 2 disposed inside the crucible 5 is melted by this heat.

In this way, heat is generated inside the heat-insulating box 9, and since the heat-insulating box 9 has a structure in which the top and bottom are covered by the upper cover 22 and the lower cover 23, the heat generated in the carbon susceptor 25 is transferred to the crucible. The structure is such that the heat is applied locally to the area surrounded by the heat insulating box 9 of No. 5. As a result, as described below,
The melting range of sendust can be narrowed, and a single crystal of sendust with a uniform composition can be grown. Furthermore, the heat generated within the heat-retaining box 9 is isolated from the outside by the upper cover 22 and the lower cover 23, so that the amount of heat leaking to the outside of the heat-retaining box 9 can be reduced. Therefore, this also makes it possible to narrow the melting range of sendust.

Next, the operation of the apparatus 1 having the above configuration and the process of growing a single crystal of sendust using the apparatus 1 will be described below.

To grow a single crystal of sendust using apparatus 1, first, a seed crystal 3 made of a single crystal of sendust and a polycrystal of sendust produced in advance in a vacuum melting and casting apparatus (see Japanese Patent Application No. 176767/1983) are grown. A round bar sample 2 having a shape of Next, the interior of Class 4 is made into a moderate vacuum atmosphere using the rotary pump 13, and then an inert or reducing gas such as Ar is supplied from the gas cylinder 12 to the interior of Class 4, for example, 1 atm, 5 atm, 10 Pressurize to atmospheric pressure. By pressurizing the inside of Class 4 in this way, it is possible to prevent the evaporation of Fe, Si, and Al, which are the raw materials for sendust.

Next, a high frequency current is passed through the high frequency heating coil 19 to heat the carbon susceptor 25 installed inside the heat insulation box 9.

This heat is transmitted to the sample 2 via the crucible 5, melts a portion of the sample 2, and forms a melted portion 26. The melted portion 26 is initially formed near the junction between the sample 2 and the seed crystal 3. At this time, the crucible 5 is rotated by driving the upper sample rotation vertical drive unit 10, thereby rotating the sample 2 as well, so as to make the temperature distribution inside the crucible 5 uniform.

The crucible 5 is gradually moved downward (in the direction of arrow B) by the upper sample rotation drive mechanism 10. Along with this movement, the molten part 26 moves relatively upward, and the part below the placement position of the heat insulating box 9 is cooled and a single crystal having the same plane orientation as the seed crystal 3 is formed. Ru.

By providing the heat insulating box 9 during the heating performed for the above-mentioned single crystal growth, the heating range for the crucible 5 is the area where the heat insulating box 9 is disposed, and heating can be performed locally. In addition, in the part of the crucible 5 other than where the heat-insulating box 9 is placed, heat is trapped in the heat-insulating box 9, so
It is never heated. Therefore, the range of the melted portion 26 can be narrowed.

As mentioned above, the magnetic properties of sendust are affected by its composition, and the raw materials (Fe, Si, A
If the particles are segregated, desired characteristics cannot be obtained. This segregation occurs due to the density difference between the raw materials constituting the sendust, with the raw material having a higher density (Fe) precipitating at the bottom, and the raw materials having a smaller density (Si, Al) precipitating at the upper part.

Furthermore, the occurrence of this segregation increases as the range of the fusion zone 26 becomes wider. Therefore, by narrowing the range of this fusion zone 26, the degree of occurrence of segregation can be reduced.

Therefore, by providing the heat insulating box 9 and narrowing the range of the melting zone 26, it is possible to prevent the occurrence of segregation, and it is possible to make the composition of the grown sendust uniform. As a result, the magnetic properties of the grown single-crystal sendust are improved, and when this is applied to a magnetic head or the like, excellent recording/reproducing properties and mechanical properties can be achieved.

Ruppo 5 continues to move in the direction of arrow B by the upper sample rotating vertical drive unit 1O, and single-crystal sendust is successively grown accordingly. When the heat-insulating box 9 reaches the top of the sample 2, high-frequency heating is performed The power supply 15 to the coil 19 is turned off, and the Ar gas inside the furnace 4 is removed to bring it to normal pressure. Then, the round rod of single-crystalized sendust is taken out from the furnace 4, and the single-crystal growth is completed.

Next, a modification of this embodiment will be explained using FIGS. 3 to 5. In each figure, the same components as those shown in FIGS. 1 and 2 are denoted by the same reference numerals, and the explanation thereof will be omitted.

The device 30 shown in FIG. 3 is characterized in that the inner part of a carbon susceptor 32 installed inside a heat insulation box 31 has a spherical shape as shown in the figure. In this way, by forming the inner part of the carbon susceptor 32 into a spherical shape, the heating range can be concentrated, and the range of the melted part can be further narrowed. Thereby, the occurrence of segregation can be further prevented, and a sendust single crystal having good properties can be grown.

The device 40 shown in FIG. 4 is a thermal insulation box 4! As shown in the figure, the inner part of the carbon susceptor 42 installed in the carbon susceptor 42 is characterized by having a narrow upper part and a wider lower part. By making the carbon susceptor 42 into the above-described shape, the high-frequency heating coil 9 heats the heat-insulating box 4! The temperature peak due to the heat generated within is located at the bottom, and this also makes it possible to narrow the range of the melting zone.

The apparatus 50 shown in FIG. 5 fixes the sample 2 to the upper chuck 7 connected to the upper sample rotation vertical drive section 10, and also fixes the crucible 5 to the lower chuck 8 connected to the lower sample rotation vertical drive section 11. The lower chuck 8 is fixed, and the descending speed V of the lower chuck 8 is constant, and the moving speed vI of the upper chuck 7 is variable.

With the above configuration, it is possible to control the range of the melting part. For example, when the range of the melting part becomes wide, the moving speed V of the upper chuck 7 in the downward direction is slowed down, and conversely, the melting part is If the range of the upper chuck 7 becomes narrower, the moving speed v1 of the upper chuck 7 in the downward direction may be controlled to be faster. Thereby, the range of the melting zone can always be kept within the appropriate range, and high-quality sendust single crystals can be grown.

In addition, in each of the above-mentioned embodiments, the heat-insulating box is arranged in the heat-insulating cylinder, and the configuration is such that it moves relative to the crucible or the heat-insulating box as the crucible moves. It is also possible to have a configuration in which only the heat-insulating box is disposed without using a cylinder, and the crucible moves and hangs relative to the heat-insulating box.

〔Effect of the invention〕

As described above, according to the present invention, since the range of the molten zone can be narrowed, the composition of the grown single crystal can be made uniform, and sendust single crystals with excellent magnetic and mechanical properties can be grown. It has features such as being able to be cultivated.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the main parts of a growing device for a Fe-Si-Aj' alloy single crystal, which is an embodiment of the present invention; 3 to 5 are diagrams for explaining modifications of the Fe-Si-Al alloy single crystal growth apparatus shown in FIGS. 1 and 2. 1.30,40.50...apparatus, 2...sample, 3.
... Seed crystal, 4... Furnace, 5... Crucible, 6... Heating mechanism, 9゜31.41... Heat insulation box, 17... Heat insulation cylinder, 19... High frequency heating coil, 25, 32.42...
Carphone susceptor, 26... Melting part, 28... Insulating tube.

Claims (1)

[Scope of Claims] A crucible containing a polycrystalline sample of a Fe-Si-Al alloy is heated by a heating means to melt the polycrystalline sample, and the heating means and the polycrystalline sample are heated to melt the polycrystalline sample. By relatively moving the sample in the longitudinal direction, Fe-Si-Al
In a Fe-Si-Al system alloy single crystal growth apparatus for growing a single crystal of a Fe-Si-Al system alloy, heat generated by the heating means is locally applied to a molten part of the crucible where the polycrystalline sample is melted. What is claimed is: 1. An apparatus for growing a single crystal of a Fe-Si-Al alloy, characterized in that it is further equipped with a heat application mechanism for preventing heat from being released to the outside.