JP2543453B2 - Method for producing intermetallic compound and composite material thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing an intermetallic compound and an intermetallic compound composite material.

[0002]

2. Description of the Related Art In general metal materials, it is possible to control a microstructure without defects by simply rotating and stirring and solidifying, and the inventor of the present invention has disclosed a method and an apparatus therefor.
It has already been proposed as No. 32. However, with an intermetallic compound having a perfect crystal structure, it is highly likely that cracks will occur during the cooling process to room temperature only by solidification by rotation stirring, and the high internal energy stored in the material is relaxed by some means. Then, it is necessary to prevent the occurrence of cracks during the cooling process. This problem also applies to the intermetallic compound composite material.

[0003]

SUMMARY OF THE INVENTION The technical problem of the present invention is to store in an intermetallic compound material when producing an intermetallic compound having a defect-free microstructure or a composite material thereof by a simple means of rotary stirring solidification. An object of the present invention is to provide a simple method for relaxing the generated high internal energy and preventing the occurrence of cracks during the cooling process to room temperature.

[0004]

Means and Actions for Solving the Problems The method for producing an intermetallic compound according to the present invention for solving the above-mentioned problems is to perform high-frequency melting of an intermetallic compound material in a vacuum or an inert atmosphere and then remove the intermetallic compound. After moving to a constant temperature bath in the same atmosphere and inserting a stirrer, the stirrer stirs the intermetallic compound at high speed during solidification to crush the crystals and form a microstructure with homogeneous fine crystal grains. It is characterized in that the material having the microstructure is returned to the inside of the high frequency furnace after stirring for a certain period of time, and the high stress generated inside the material is relieved by heating again with the high frequency.

The method for producing an intermetallic compound composite material according to the present invention is the same as the method for producing an intermetallic compound described above,
It is characterized in that a reinforcing material is added to the intermetallic compound raw material at the stage of putting the raw material into the crucible for melting or at the stage until stirring and solidification.

Examples of the intermetallic compound produced by the method of the present invention include TiAl, Ti ₃ Al, Al ₃ Ti, Nb ₃ Al, Nb ₂ Al, N.
iAl, Ni ₃ Al, Co ₃ Al, Co ₂ Nb, Mo ₅ Si ₃ , Cr ₃ Si, Cr ₂ Nb, FeAl, Al
₃ V, Al ₃ Nb, Al ₃ Zr, Mo ₃ Al ₈ , MoSi ₂ , Ti ₅ Si ₃ , Nb ₅ Si ₃ , Nb ₂ Be ₁₇ ,
Although ZrBe _{13 and the} like are common, the present invention can be applied to various other intermetallic compounds and also to composite materials of those intermetallic compounds. The same applies to the intermetallic compound in the case of forming a composite material.

As a reinforcing material compounded with an intermetallic compound, a material generally used as a reinforcing material, for example, Ti
Particles such as B ₂ , TiC, WC, NbC, VC, TaC, SiC, Al ₂ O ₃ or short fibers can be mentioned, but the interface between the intermetallic compound matrix and the reinforcing material is relatively smooth. is necessary.
In addition, the filling amount of this reinforcing material is generally appropriate within the range of 0.1 to 70% with respect to the volume of the intermetallic compound.

Rotational stirring of the intermetallic compound at a high speed by a stirrer generally requires about 0.1 to 10 min in order to crush the crystals and obtain homogeneous fine crystal grains. In addition, when the material of the microstructure is returned to the high-frequency furnace and reheated after the stirring, the heating temperature needs to be about 500 ° C or less below the material solidification temperature, and the heating time is 10 Approximately 10,000 min
It is necessary to relieve the high stress generated inside the material and prevent cracking during the cooling process.

Next, the method of the present invention will be described in detail with reference to the intermetallic compound production apparatus shown in FIG. The apparatus shown in the figure inserts a stirrer into the intermetallic compound that is high-frequency melted in a thermostat in a vacuum or inert atmosphere, and rotates the stirrer at a high speed up to about 5000 rpm during solidification of the intermetallic compound. Then, the crystal is crushed and a microstructure having homogeneous and fine crystal grains appears. After stirring for a certain period of time, the material of the above microstructure is placed in a high-frequency furnace, and high-frequency heating is performed again to relieve the high stress generated inside the sample by forced rotation stirring, thereby causing intermetallic compounds. Prevents cracking of the material during the cooling process.

Explaining the structure of this apparatus in detail, the chamber body 1 having a hinged opening / closing door on the front surface constitutes a vacuum container, and the inside of the chamber body 1 is agitated by rotating and stirring a high-frequency molten intermetallic compound material. An upper-stage motor chamber 2 which houses a rotary drive motor 5 of a stirrer 6 for solidification, and a middle-stage agitation solidification equipped with a constant temperature bath 8 which houses a crucible 7 of the intermetallic compound material during rotational stirring of the intermetallic compound material. The chamber 3 and the lower melting chamber 4 provided with a high-frequency furnace 9 for high-frequency heating the intermetallic compound material are divided into three stages. Although not shown, the chamber body 1 is connected to an evacuation device for evacuation, and is also connected to a gas introduction device for introducing a necessary inert gas.

The upper motor chamber 2 accommodates the rotary drive motor 5 and has its output shaft 10 supported by a bearing 11 provided with a water cooling / cooling device 12 provided on a partition wall between the interrupted stirring and solidifying chamber 3. There is. A rotation detector 13 is attached to the output shaft 10 of the motor 5. When the rotary drive motor 5 is installed outside the vacuum chamber body 1, the stirrer 6 is inserted into the high-temperature molten metal in the vacuum chamber body 1 to rotate at high speed. Therefore, the output shaft 10 of the motor 5 is placed in the vacuum chamber. Although it has to be introduced into the inside through the outer wall of the main body 1, a high load is applied to the seal portion that seals the introduction portion, and there is a structural defect that the seal member must be frequently replaced. In addition, when the rotation driving motor 5 for stirring is put in the vacuum chamber body 1, such a problem is also solved.

The stirring and solidifying chamber 3 in the middle stage is provided with a constant temperature bath (resistance heating furnace) 8 for holding the sample temperature at a constant temperature. The constant temperature bath 8 is surrounded by heat insulating materials 15a to 15c. It is configured by arranging the heater 16 inside. A hole through which the output shaft 10 of the motor 5 penetrates is provided in the center of the heat insulating material 15a above the constant temperature bath 8.
A stirrer 6 made of metal having an octagonal cross section is attached to the lower end of the output shaft 10 in the constant temperature bath 8 so that it can be rotationally driven by a rotary drive motor 5. This stirring bar 6
Use the same chemical composition as the composition of the intermetallic compound material, or one element (pure metal) in the element group that composes the composition. To prevent pollution.

Further, the constant temperature bath 8 has a heat insulating material 15 at the bottom thereof.
The crucible 7 can be accommodated through the opening 16 provided in c, and further penetrates the heat insulating material 15b on the side surface thereof to form the thermocouple 1.
7 is inserted. In the figure, reference numeral 14 denotes a crucible monitoring mirror that leads to the viewing window.

On the other hand, the lower melting chamber 4 is provided with a high-frequency furnace 9 for heating the intermetallic compound material at high frequency, and a high-frequency coil 19 is provided around a heat insulating material 18 which encloses the peripheral side surface of the high-frequency furnace 9. A crucible lid 20 which is configured by being arranged and which can be opened and closed by an operation from the outside is arranged above the high-frequency furnace 9.

Further, the crucible 7 is installed in the high-frequency furnace 9 so as to be able to move up and down by an elevator mechanism (not shown) provided below the high-frequency furnace 9. This lifting mechanism allows the crucible 7 to be selectively moved and held in the high-frequency furnace 9 and the constant temperature bath 8.
When raising the crucible 7 into the thermostat 8, the crucible lid 20
The elevating mechanism is operated in a state in which is opened to drive the crucible 7 upward. Further, the crucible 7 is installed in the center thereof as a double crucible including a calcia inner crucible 21 and a graphite outer crucible 22.

In the intermetallic compound manufacturing apparatus having the above-mentioned structure, the material for forming a required intermetallic compound is put in the crucible 7 and housed in the high frequency furnace 9, and the chamber body 1 is evacuated by the vacuum evacuation device. Then, an inert gas is introduced to dissolve the material in the inert atmosphere.
In the case of producing an intermetallic compound composite material, a required amount of the reinforcing material can be mixed in the intermetallic compound raw material at the stage of putting the raw material into the crucible.

In the high frequency furnace 9, after reaching a predetermined gas atmosphere pressure, high frequency heating is performed in the above vacuum or inert atmosphere to melt the material within a short time. After that, the crucible lid 20 directly above the high-frequency furnace is opened, and the crucible elevating mechanism raises the crucible 7 containing the molten metal.
Then, the stirring bar 6 is inserted into the molten metal in the constant temperature bath 8 and rotated at a relatively low speed, and the rotational speed of the stirring bar 6 is gradually increased to reach a predetermined speed.

After that, the stirring bar 6 is kept at a constant speed for a predetermined time.
By continuing high-speed rotation stirring by, the crystal is crushed, a microstructure with homogeneous fine crystal grains appears, and when it is completed after stirring for a certain period of time, the crucible 7 is placed in the high-frequency furnace 9 by the lifting mechanism. By lowering and preventing welding of the stirrer 6 and the raw material, at the same time, by heating again in the high frequency furnace 9, the high stress generated inside the raw material by the forced rotary stirring is relaxed, and the intermetallic compound raw material is cooled. Prevent cracking in the process.

In the case of producing an intermetallic compound composite material, it is possible to add a reinforcing material to the intermetallic compound raw material at the stage of stirring and solidifying the molten metal of the intermetallic compound raw material. The desired composite material can be obtained by exactly the same operation. However, in this case, a reinforcing material feeding chamber having a necessary amount of reinforcing material stored in advance in the stirring and solidifying chamber 3 and a reinforcing material feeding device having charging means for charging the reinforcing material into the crucible 7 are additionally provided. There is a need to.

[0020]

EXAMPLE An example of manufacturing an intermetallic compound sample (Ti-31 wt% Al alloy) by the apparatus shown in FIG. 1 will be described below. In the above device, the rotary drive motor 5 for the stirring bar 6
The one that can rotate the stirrer 6 at a maximum speed of 5000 rpm with 2.2 horsepower is used.
It was measured by the rotation detector 13 attached to 0 and recorded on the digital display. In addition, the temperature measurement was performed by using a radiation thermometer to measure the central portion of the outer wall of the graphite outer crucible 22 and the crucible lid 20.
The actual temperature was determined by investigating the correlation from the temperature measured by observing and measuring the material directly through the viewing window after opening. further,
The stirrer 6 is made of pure titanium and has an octagonal pyramid shape with a horizontal axis of the upper end of 38 mm, a short axis of 30 mm, a long axis of the lower end of 32 mm, a short axis of 25 mm, and a length of 120 mm. I was there.

As the operation, first, the composition is Ti-31 wt% Al.
As a result, granular sponge titanium with a purity of 99.5% or more and aluminum strips with a purity of 99.99% are about 380 g in total.
Blended, 55mm inner diameter, 83mm outer diameter, depth 130
It was placed in an inner crucible 21 made of calcia having a size of mm for processing. In the above apparatus, the crucible containing the sample was loaded into the high-frequency furnace 9, the inside of the chamber main body was evacuated to 1 × 10 ⁻⁵ torr or less, and then argon gas was introduced as an inert gas to 800 to
The argon gas atmosphere pressure was set to about rr. After a while
The sample was heated at high frequency to dissolve the sample in a short time.

This melting is measured by a radiation thermometer on the side surface of a graphite outer crucible installed to uniformly heat the calcia inner crucible in the high-frequency furnace 9 in the lower stage of the vacuum chamber body 1, and the graphite outer crucible is measured. It was confirmed that the temperature of the side surface of the sample reached 1100 ° C. and the sample was dissolved. At this point, the crucible lid 20 immediately above the high-frequency furnace 9 was opened, the sample was confirmed to have melted with a crucible monitoring mirror, and the crucible 7 containing the molten metal was raised by an elevating mechanism to move it in the thermostat 8. The stirrer 6 made of pure titanium was inserted into the molten metal, and when the lower end of the stirrer 6 reached a position 10 mm above the inner bottom of the crucible, the ascending of the crucible was stopped.

Next, the stirrer 6 is rotated at a relatively low speed of about 900 rpm, the rotation speed of the stirrer 6 is gradually increased, and finally 900 to 50 depending on the sample.
It was held at several stages of 00 rpm. At that time, in order to prevent as much as possible the scattering of the semi-solidified material outside the crucible 7 due to the rapid speedup of the rotary stirring, the increasing speed of the rotation speed was kept constant. After that, the rotary stirring is continued at the above-mentioned constant speed for an appropriate time according to the sample, and the sample is lowered into the high-frequency furnace 9 by the crucible elevating mechanism while observing the time point from the latter half of the solidification until just before the completion of the solidification, thereby stirring. After preventing the welding of the sample 6 and the sample, in the high frequency furnace 9 again at 1000 ° C. for about 1
High frequency heating for 0 minutes was performed. For comparison, a standard sample was prepared by removing the stirrer and spontaneously solidifying the molten metal in the constant temperature bath 8.

The photograph of FIG. 2 shows a normal solidification microstructure (comparative example) of a standard sample of a Ti-31 wt% Al alloy obtained by melting the above sample under an argon atmosphere pressure of 800 torr. In this case, a distinct layered structure of TiAl ₃ and TiAl is observed.
In addition, in the photograph of FIG.
Dissolve at 00 torr and set the final rotation speed of the stir bar to 900
1 shows the microstructure of a Ti-31 wt% Al alloy spin-solidified as rpm (no increase from initial rotation speed).
In this case, the rotation time of the stirrer was 30 seconds after the completion of inserting the stirrer into the molten metal, and immediately after that, the crucible was lowered by the crucible lifting mechanism to prevent the sample and the stirrer from being welded. further,
In the photograph of Fig. 4, the same sample was subjected to an argon atmosphere pressure of 800 torr.
2 shows a microstructure of a Ti-31 wt% Al alloy that was melted by stirring and solidified by stirring at a rotation speed of a stirrer of 4200 rpm. In this case, the rotation time of the stirring bar was 20 seconds after the stirring bar was completely inserted into the molten metal, and immediately after that, the crucible lifting mechanism lowered the crucible to prevent welding of the sample and the stirring bar.

The sample in the case where the stirrer shown in FIG. 3 rotates at a low speed has a relatively long rotation period, so that the sample is sufficiently stirred, the layered structure is completely destroyed, and a fine microstructure appears. Is observed. On the other hand, when the stirrer in FIG. 4 rotates at a high speed, the rotation period is comparatively short, so stirring is somewhat insufficient, but finer crystals are observed. In the samples of FIGS. 3 and 4, the high stress generated inside the sample is relaxed by the forced rotary stirring, cracks are prevented in the cooling process of the sample, and a fine microstructure is obtained. I was able to.

As described above in detail, according to the production method of the present invention, when an intermetallic compound having a microstructure having no defect or a composite material thereof is produced by a simple means of rotary stirring solidification, the intermetallic compound is used. The high internal energy stored in the intermetallic compound material can be relaxed by the high frequency heating of the compound again, and the occurrence of cracks during the cooling process to room temperature can be prevented.

[Brief description of drawings]

1 is a cross-sectional view of an apparatus for performing the method of the present invention.

FIG. 2 Ti-31 melted under an argon atmosphere pressure of 800 torr
It is a drawing-substitute micrograph showing a normal solidification microstructure of a wt% Al alloy.

FIG. 3 is a drawing-substituting photograph showing a microstructure of a Ti-31 wt% Al alloy melted under an argon atmosphere pressure of 800 torr and stirred and solidified at a rotation speed of a stirrer of 900 rpm.

FIG. 4 is similarly dissolved, and the rotation speed of the stirring bar is 4200.
It is a drawing substitute photograph which shows the microstructure of the Ti-31wt% Al alloy stir-solidified at rpm.

[Explanation of symbols]

6 stirrer, 8 constant temperature bath, 9
High frequency furnace.

Claims (2)

(57) [Claims] 1. After high-frequency melting of an intermetallic compound material in a vacuum or an inert atmosphere, the intermetallic compound is moved into a constant temperature bath in the same atmosphere and a stirrer is inserted, and the intermetallic compound is removed by the stirrer. Rotate and stir at high speed during the solidification,
The crystals were crushed, a microstructure with uniform fine grains appeared, and after stirring for a certain period of time, the material of the microstructure was returned to the high-frequency furnace and high-frequency heating was performed again inside the material A method for producing an intermetallic compound, which comprises relaxing stress. 2. The intermetallic compound composite according to claim 1, wherein a reinforcing material is added to the intermetallic compound raw material at the stage of putting the raw material into the crucible for melting or at the stage until stirring and solidification. Material manufacturing method.