JP2002038236A - Low thermal expansion heat-resistant alloy and method for producing the same - Google Patents

Abstract

[PROBLEMS] To provide a low-thermal-expansion heat-resistant alloy having high room-temperature strength and high-temperature strength and a low coefficient of thermal expansion, and a method for producing the same. SOLUTION: The low thermal expansion heat-resistant alloy is 20 to 50% of nickel, 25% or less of cobalt, and 5 to 15% of niobium in weight%.
%, 2 to 10% of titanium, at least 1% of at least one of aluminum and silicon, 0.2 to 2.0% of carbon, and a mixed powder having a crystal grain size of 5 μm or less having a balance of iron and unavoidable impurities. After the preparation, the mixed powder can be manufactured by sintering in a non-oxidizing atmosphere at a sintering temperature of 900C to 1300C. This heat-resistant alloy has a thermal expansion coefficient of 12 × 10 ⁻⁶ from room temperature to 600 ° C.
/ ° C or less and strength at room temperature of 1000
The strength at 600 ° C. at 800 MPa or higher is 800 MPa or higher.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a low thermal expansion coefficient,
The present invention relates to a low thermal expansion heat-resistant alloy having high room temperature strength and high temperature strength and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, as a composite material of a gas turbine component, a ceramic and a cemented carbide, or a component material of a device for performing precision machining at a high temperature, a temperature ranging from a normal temperature to a temperature exceeding about 600 ° C. is reached. Heat-resistant alloys exhibiting a low coefficient of thermal expansion have been developed and put to practical use so that the strength is maintained up to that point and the dimensional change of the component is within an allowable range over the temperature range.

[0003] For example, Japanese Patent Application Laid-Open No. 4-21864.
No.2 is carbon 0.1% or less, silicon 1% or less by weight%
Bottom, manganese 1% or less, titanium 0.5-2.5%, Nio
Bu 3.0-6.0%, boron 0.01% or less, aluminum
Containing 1.0% or less of nickel and 20-32% of nickel
And 16% to 30% of cobalt at 48.8 ≦ 1.235x
Ni + Co is contained in the range of 55.8, and the balance is substantially
It describes a low thermal expansion super heat resistant alloy made of iron. This
Heat-resistant alloy has an average coefficient of thermal expansion from room temperature to 400 ° C
Is 7.0x10^-6/ ° C or lower, and 1 at 500 ° C.
00kgf / mm ^TwoHas the above tensile strength characteristics
You.

Japanese Patent Publication No. 4-1057 discloses that 34% to 55% of nickel, up to 25% of cobalt, 1% to 2% of titanium, 1.5% to 5.
5% niobium, 0.25% to 1% silicon, 0.1
% Of carbon and the balance substantially consisting of iron and inevitable impurities is described. This controlled expansion alloy has a thermal expansion coefficient of 9.9 × 10 ⁻⁶ / ° C. or less between room temperature and a refraction temperature (329 ° C.).
It has a tensile property of about 100 to 110 kgf / mm ² at 38 ° C.

[0005]

However, the development of a low thermal expansion heat resistant alloy which can be used stably even under severer high temperature conditions, especially a low thermal expansion heat resistant alloy having improved strength characteristics at 600 ° C., and especially 700 ° C. Development is awaited.

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a low thermal expansion heat-resistant alloy having high strength characteristics even in the above-mentioned temperature range. That is, the low-thermal-expansion heat-resistant alloy according to claim 1 of the present invention has a nickel content of 20 to 50%, a cobalt content of 25% or less, and a niobium content of 5 to 5% by weight.
15%, titanium 2-10%, at least one of aluminum and silicon 1% or less, carbon 0.2-2.0%,
The balance consists of iron and unavoidable impurities, the strength at room temperature is 1000 MPa or more, the strength at 600 ° C. is 800 MPa or more, and the coefficient of thermal expansion from room temperature to 600 ° C. is 12 × 10 ⁻⁶ / ° C. or less. Features.

According to a second aspect of the present invention, in the first aspect, the low thermal expansion heat-resistant alloy has an average crystal grain size of 5 μm or less, more preferably 1 μm or less.

The invention of claim 3 is characterized in that, in the invention of claim 1 or 2, the low-thermal-expansion heat-resistant alloy contains a precipitate of an intermetallic compound and a carbide which are elements constituting the above-mentioned alloy composition. .

Another object of the present invention is to provide a method for producing a low thermal expansion heat-resistant alloy having high ordinary-temperature strength and high-temperature strength without performing a solution treatment or an aging treatment requiring a long time. . That is, the method for producing a low thermal expansion heat-resistant alloy according to claim 4 of the present application is as follows.
0-50%, cobalt 25% or less, niobium 5-15%,
A step of preparing a mixed powder so that titanium has a composition of 2 to 10%, at least one kind of aluminum and silicon of 1% or less, carbon of 0.2 to 2.0%, and a balance of iron and unavoidable impurities; And a step of sintering.

According to a fifth aspect of the present invention, in the fourth aspect of the invention, the mixed powder is produced by a mechanical alloying method or a mechanical milling method, and has a crystal grain size of 1 μm.
It is characterized by the following.

The invention of claim 6 is characterized in that, in the invention of claim 4 or 5, the mixed powder is sintered at a sintering temperature of 900 to 1300 ° C.

A seventh aspect of the present invention is characterized in that, in any one of the fourth to sixth aspects, the mixed powder is produced by a mechanical milling method using an alloy powder having the above alloy composition as a raw material. .

According to an eighth aspect of the present invention, in any one of the fourth to sixth aspects of the present invention, the mixed powder is produced by a mechanical alloying method using a powder of each single element constituting the alloy composition as a raw material. It is characterized by.

According to a ninth aspect of the present invention, in any one of the fourth to sixth aspects of the present invention, the mixed powder comprises at least two or more alloy powders of the above-mentioned alloy composition and powders of the remaining individual elements. The invention according to claim 10 is characterized in that the alloy powder is manufactured by a mechanical alloying method using as a raw material, wherein the alloy powder is an iron-nickel-cobalt alloy powder in the invention according to claim 9. .

According to an eleventh aspect, in the ninth aspect, the alloy powder contains at least one of titanium carbide, niobium carbide, and cobalt carbide.

According to a twelfth aspect of the present invention, in any one of the fourth to sixth aspects of the present invention, the mixed powder is a powder of at least one hydride powder of the elements constituting the alloy composition and a powder of each of the remaining simple elements. Alternatively, it is characterized in that it is produced by a mechanical alloying method using at least two or more alloy powders of the elements constituting the above alloy composition and powders of the remaining individual elements as raw materials.

According to a thirteenth aspect, in the twelfth aspect, the hydride is heptane or another hydrocarbon.

According to a fourteenth aspect, in the twelfth aspect, the hydride is titanium hydride.

According to a fifteenth aspect of the present invention, in any one of the fourth to fourteenth aspects, the mixed powder is sintered by spark plasma sintering, hot press sintering, or metal powder injection sintering. It is characterized by the following.

The invention of claim 16 is characterized in that, in any one of the inventions of claims 4 to 15, after sintering the mixed powder, the obtained sintered body is rapidly cooled from a sintering temperature.

According to a seventeenth aspect, in the sixteenth aspect, after the above-described sintered body is rapidly cooled, the sintered body is subjected to hot working at a predetermined temperature.

The invention of claim 18 is characterized in that, in the invention of claim 16, after the above-mentioned sintered body is rapidly cooled, the sintered body is subjected to an aging treatment at a predetermined temperature.

The invention of claim 19 is the invention according to any one of claims 4 to 15, wherein after sintering the mixed powder, the obtained sintered body is subjected to a solution treatment at a first heat treatment temperature. After quenching the sintered body from the first heat treatment temperature, aging treatment is performed at the second heat treatment temperature.

According to a twentieth aspect, in any one of the fourth to fifteenth aspects, after sintering the mixed powder, the obtained sintered body is subjected to a solution treatment at a first heat treatment temperature. After quenching the sintered body from the first heat treatment temperature, hot working is performed at the second heat treatment temperature.

It is a further object of the present invention to provide a low thermal expansion heat resistant alloy manufactured under specific conditions by powder metallurgy without performing a solution treatment or an aging treatment that requires a long time. . That is, the low-thermal-expansion heat-resistant alloy according to claim 21 of the present invention has a nickel content of 20 to 50 wt%.
%, Cobalt 25% or less, niobium 5-15%, titanium 2
-10%, at least one of aluminum and silicon
A mixed powder having a composition of 1% or less of seeds, 0.2 to 2.0% of carbon, and the balance of iron and unavoidable impurities and having a crystal grain size of 5 μm or less is prepared.
It is manufactured by sintering at a sintering temperature of 900C to 1300C.

Hereinafter, the present invention will be described in detail. The low-thermal-expansion heat-resistant alloy of the present invention has a nickel content of 20 to 50% by weight.
%, Cobalt 25% or less, niobium 5-15%, titanium 2
-10%, at least one of aluminum and silicon
1% or less of seeds, 0.2 to 2.0% of carbon, the balance being iron and unavoidable impurities. In particular, a typical alloy composition of the low thermal expansion heat-resistant alloy of the present invention is 35% nickel by weight.
± 1%, cobalt 12% ± 1%, niobium about 10% ± 1
%, Titanium 5% ± 0.5%, aluminum 0.05% ±
0.02%, Silicon 0.5% ± 0.1%, Carbon 1.0
% ± 0.2%, with the balance being iron and unavoidable impurities.

In the present invention, the carbon content is set to 0.2 to 2.
In addition to the range of 0%, the composition range of elements that easily form carbides such as niobium and titanium is increased. This makes it possible to sufficiently precipitate both carbides such as NbC and TiC and intermetallic compounds such as Ni-Al and Ni-Ti (gamma prime phase). As described above, the above-mentioned carbon content and the composition range of niobium and titanium are particularly important for improving the alloy strength from room temperature to 700 ° C. (particularly, up to 600 ° C.).

The low-thermal-expansion heat-resistant alloy having the above-mentioned alloy composition is at least 1000 MPa at room temperature, preferably 16 MPa.
Strength of 100 to 1700 MPa and 80 at 600 ° C.
It has a strength of 0 MPa or more, preferably 1200 to 1300 MPa, and has a coefficient of thermal expansion from room temperature to 600 ° C. of 12 × 10 ⁻⁶ / ° C. or less, more specifically 8 × 10 ⁻⁶ / ° C.
１１11 × 10 ⁻⁶ / ° C.

In order to stably provide the above strength characteristics, the average crystal grain size of the low thermal expansion heat resistant alloy is 5 μm.
m or less, particularly preferably 1 μm or less. Further, it is preferable that the precipitated fine particles of the intermetallic compound and the carbide, which are the elements constituting the above alloy composition, are uniformly dispersed in the low thermal expansion heat resistant alloy.

The low thermal expansion heat-resistant alloy of the present invention comprises,
Nickel 20-50%, Cobalt 25% or less, Niobium 5
-15%, titanium 2-10%, at least one of aluminum and silicon 1% or less, carbon 0.2-2.0
%, With the balance being iron and unavoidable impurities, and producing a mixed powder, and sintering the mixed powder.

A conventional low-thermal-expansion heat-resistant alloy is prepared by casting a fusion alloy produced to have the above-described alloy composition, and then performing a solution treatment and an aging treatment to form relatively large crystal grains into a metal such as γ ′ phase. Intermediate compounds are precipitated to ensure high-temperature strength. However, the solution treatment and the aging treatment require a very long time, and are a major factor in lowering the production efficiency of the alloy. Therefore, according to the method for producing a low-thermal-expansion heat-resistant alloy of the present invention, it is possible to provide a low-thermal-expansion heat-resistant alloy having high room-temperature strength and high-temperature strength at an improved production efficiency without performing a solution treatment or an aging treatment. You can.

In preparing the mixed powder, it is particularly preferable to employ a mechanical alloying method or a mechanical milling method. Mechanical alloying is a method of applying two or more powders (mixed powder of two or more elemental element powders, two or more alloy powders, (A mixture of elemental element powders may be mixed) to produce an alloy powder. On the other hand, the mechanical milling method
This is a method in which a fine structure, amorphous powder, or the like is produced while giving a mechanical impact to one kind of powder (either an alloy powder or a single element powder). The mechanical milling method is not particularly limited, and examples thereof include a case where ball milling or planetary ball milling is performed for 20 to 60 hours in an inert gas atmosphere such as argon gas.

As the raw material powder before the mechanical alloying method or the mechanical milling method, an alloy powder having an average particle diameter of 200 μm or less obtained by gas atomizing or coarsely pulverizing an alloy having the above-mentioned alloy composition, or a gas atomizing method Alternatively, a powder of each single element constituting the above-mentioned alloy composition having an average particle diameter of 200 μm or less obtained by a water atomizing method or coarse pulverization can be used.

It is also preferable to prepare a mixed powder by a mechanical alloying method using at least two or more alloy powders of the elements constituting the above-mentioned alloy composition and the powders of the remaining individual elements as raw materials. Examples of the alloy powder of at least two or more elements constituting the alloy composition include, for example,
It is preferable to use a Kovar alloy, which is an iron-nickel-cobalt alloy, and at least one of titanium carbide, niobium carbide, and cobalt carbide.

By using a Kovar alloy, which is a low thermal expansion alloy, as a raw material powder, the time of mechanical alloying can be reduced. In addition, when easily oxidizable metals such as titanium and niobium are supplied as carbides such as TiC and NbC, a mixed powder having a lower oxygen content should be prepared as compared with the case where powders of these pure metals are used as raw materials. This is suitable for obtaining a sound alloy having a low oxygen content after sintering.

Further, a mixed powder may be prepared by a mechanical alloying method using at least one hydride powder of the elements constituting the above-mentioned alloy composition and the powder of the remaining individual elements as raw materials. In this case, it is preferable to use heptane or other hydrocarbons or titanium hydride as the hydride. For example, when a mixed powder is produced by a mechanical alloying method using a hydrocarbon such as heptane or a hydride such as TiH ₂ as a carbon material, a powder having an average particle diameter of about 10 to 30 μm is mixed with a polypropylene resin and wax. Alternatively, after kneading with a polyacetal resin and an organic binder mainly composed of wax, etc., to prepare pellets for injection molding, injection molding in a mold with an injection molding machine to produce a molded body, and removing the organic binder by heat degreasing. For example, the low-thermal-expansion heat-resistant alloy of the present invention can be produced by ordinary sintering under a temperature condition of about 1200 to 1300 ° C. in a vacuum. Thus, by employing the ordinary sintering method, it is possible to mass-produce alloy parts having a complicated three-dimensional shape having a low thermal expansion and a high proof stress up to a high temperature at a relatively low cost.

The mixed powder immediately before the sintering step has an average crystal grain size of 5 μm or less, particularly preferably 1 μm or less.
It is particularly preferable to perform sintering at a sintering temperature of 900 to 1300 ° C. When the crystal grain size and the sintering temperature of the mixed powder are in the above ranges, good room-temperature strength and high-temperature strength can be stably obtained. In sintering the mixed powder, it is preferable to employ a spark plasma sintering method, a hot press sintering method, or a metal powder injection sintering method. As an example, when hot-press sintering is performed, a sintering temperature of 1000 to 1100 ° C. under a pressure of 30 to 50 MPa in a non-oxidizing atmosphere, particularly a vacuum atmosphere,
It is preferable to sinter for minutes. When plasma sintering is performed, a pressure of 30 MPa is applied in a vacuum atmosphere.
Sintering is preferably performed at a sintering temperature of 000 ° C. for 5 to 60 minutes. By these sintering processes, the average particle size is several μm or less,
Preferably, an alloy structure in which carbide particles (NbC and the like) are uniformly and finely precipitated at 1 μm or less can be obtained.

In the present invention, a low thermal expansion heat-resistant alloy having high ordinary-temperature strength and high-temperature strength can be obtained by the above-mentioned powder metallurgy method without performing solution treatment or aging treatment. It does not prohibit solution treatment or aging treatment on the sintered body. That is, carbide particles are uniformly precipitated in the low-thermal-expansion heat-resistant alloy manufactured by the powder metallurgy method, and itself has excellent room-temperature strength and high-temperature strength at 600 ° C. However, depending on the setting of the cooling rate after sintering, precipitation of an intermetallic compound such as the γ-prime phase may not be sufficiently generated, or a coarse intermetallic compound may be precipitated. Therefore, if necessary, only the aging process,
Alternatively, the aging treatment after the solution treatment promotes the precipitation of fine intermetallic compounds, and can further improve the strength of the low thermal expansion heat-resistant alloy at a temperature higher than 600 ° C. (700 ° C.).

Specifically, after sintering the mixed powder, it is effective to rapidly cool the obtained sintered body from the sintering temperature by gas cooling or the like. For example, it is preferable to cool at a cooling rate of 20 ° C./min or more using an inert gas such as argon or nitrogen. Thereby, coarsening of the structure can be effectively suppressed, and this is effective in obtaining an alloy with improved strength from room temperature to 700 ° C.

It is also preferable that the obtained sintered body is rapidly cooled from the sintering temperature by gas cooling or the like, and then the sintered body is subjected to hot working at a predetermined temperature. For example, after quenching from the sintering temperature to about 100 ° C. or less, hot forging, hot rolling, hot extrusion, or the like may be performed at about 750 ° C. By hot working after quenching, the average crystal grain size becomes several μm or less, and lattice defects such as dislocations serving as precipitation nuclei are uniformly introduced by the working, so that carbides or intermetallic compounds such as Ti-Al ( γ ′ phase) is uniformly and finely precipitated to further improve the strength from room temperature to 700 ° C. The hot working may be performed by rapidly cooling to a predetermined hot working temperature and without cooling to 100 ° C. or lower.

Further, it is preferable that the obtained sintered body is rapidly cooled from a sintering temperature by gas cooling or the like, and then the sintered body is subjected to an aging treatment at a predetermined temperature. For example, after quenching from the sintering temperature to about 100 ° C. or less, aging treatment may be performed at about 750 ° C. for about 10 hours. By aging treatment after quenching, the average crystal grain size becomes several μm or less, and carbides or intermetallic compounds such as Ti-Al
(γ ′ phase, etc.) can be uniformly and finely precipitated to further improve the strength from room temperature to 700 ° C.

After sintering the obtained mixed powder, the sintered body is subjected to a solution treatment at a first heat treatment temperature, and the sintered body is rapidly cooled from the first heat treatment temperature. It is also preferable to perform aging treatment. For example, the solution treatment at the first heat treatment temperature is 950 ° C. to 1100 ° C.
It is preferable to hold at the temperature of 2 hours. When the sintered body is rapidly cooled from the first heat treatment temperature, it is preferable to cool the sintered body to about 100 ° C. or less by water quenching, oil quenching, or gas quenching. On the other hand, as the aging treatment at the second heat treatment temperature, for example, an aging treatment of maintaining the temperature at 750 to 850 ° C. for 10 hours can be exemplified. After quenching after the solution treatment, aging treatment is performed to precipitate carbides or intermetallic compounds such as Ti-Al uniformly and finely.
° C) can be further improved.

After sintering the obtained mixed powder, the sintered body is subjected to a solution treatment at a first heat treatment temperature, and the sintered body is rapidly cooled from the first heat treatment temperature. It is also preferable to perform hot working. For example, the solution treatment at the first heat treatment temperature is 950 ° C. to 1100 ° C.
It is preferable to hold at the temperature of 2 hours. When the sintered body is rapidly cooled from the first heat treatment temperature, it is preferable to cool the sintered body to about 100 ° C. or less by water quenching, oil quenching, or gas quenching. Further, examples of the hot working at the second heat treatment temperature include, for example, performing hot forging, hot rolling, or hot extrusion at a temperature of 750 to 850 ° C. After quenching after the solution treatment, carbides or intermetallic compounds such as Ti-Al are uniformly and finely precipitated by performing hot working, so that the room temperature strength and high temperature strength (700 ° C.) of the obtained alloy are reduced. Further improvements can be made. The hot working may be performed by rapidly cooling to a predetermined hot working temperature and without cooling to 100 ° C. or lower.

[0044]

BEST MODE FOR CARRYING OUT THE INVENTION The low thermal expansion heat-resistant alloy of the present invention and a method for producing the same will be specifically described based on the following examples. (Example 1) An alloy composed of about 35% of nickel, about 15% of cobalt, about 10% of niobium, about 5% of titanium, about 0.1% of aluminum, about 1% of carbon, and the balance of iron in weight% The alloy was prepared and coarsely pulverized so that the average particle size was about 200 μm or less. The obtained powder was put into a stainless steel ball mill pot together with a stainless steel ball, argon gas was sealed in the pot, and ball milling was performed for 48 hours.
Thereby, an alloy powder having an average particle size of about 2 to 3 μm was obtained. This alloy powder is filled in a mold for spark plasma sintering, and the pressure is 10 MPa at 1000 ° C. under a pressure of 30 MPa in a vacuum.
Spark plasma sintering was performed for a minute. Thus, a sintered body of the low thermal expansion heat-resistant alloy of the present invention was obtained. This sintered body was processed into a predetermined shape to prepare a test piece for strength evaluation. As a result of the strength measurement, the 0.2% proof stress at room temperature and 600 ° C. was 1620 MPa and 1200 MPa, respectively. The coefficient of thermal expansion from room temperature to 600 ° C. is 8 to
It was within the range of 11 × 10 ⁻⁶ / ° C. (Example 2) The composition is such that nickel is about 30%, cobalt is about 15%, niobium is about 10%, titanium is about 5%, aluminum is about 0.1%, carbon is about 1%, and the balance is iron. Nickel, cobalt, niobium, titanium, aluminum,
Weigh each powder of graphite and graphite, put these powders in a stainless steel ball mill pot with stainless steel balls,
Argon gas was sealed in the pot and ball milled for 60 hours. In addition, as the powder of each single metal used as a raw material powder, a powder having an average particle diameter of 200 μm or less produced by a gas atomization method, a water atomization method, or coarse pulverization was used. Thus, a mixed powder for sintering was obtained. This mixed powder was filled in a mold for hot press sintering, and hot press sintering was performed at 1100 ° C. for 20 minutes in a vacuum at a pressure of 50 MPa. Thus, a sintered body of the low thermal expansion heat-resistant alloy of the present invention was obtained. This sintered body was processed into a predetermined shape to prepare a test piece for strength evaluation. As a result of the measurement, the 0.2% proof stress at room temperature and 600 ° C. was 1
It was 650 MPa and 1125 MPa. The coefficient of thermal expansion from room temperature to 600 ° C. is 8 to 11 × 10 ⁻⁶ / ° C.
Was within the range. (Example 3) The composition is about 35% by weight of nickel, about 15% of cobalt, about 10% of niobium, about 5% of titanium, about 0.5% of silicon, about 0.1% of aluminum, about 1% of carbon, about 1% of carbon,
Fe-29% Ni-17% Co alloy powder (Kovar alloy powder), nickel powder, titanium powder, silicon powder, aluminum powder, and heptane as a hydrocarbon were weighed so that the balance was iron. About 15% of nickel, about 10% of niobium, about 5% of titanium
%, About 0.5% of silicon, about 0.1% of aluminum, about 5% of heptane, and the remainder was Kovar alloy powder. These powders were placed in a stainless steel ball mill pot together with stainless steel balls, and argon gas was sealed in the pots.
Pulverization was performed by mechanical alloying for 8 hours using a planetary ball mill. As a result, a mixed powder having an average particle size of 1 μm or less was obtained. This mixed powder was filled in a mold for spark plasma sintering, and the pressure was 30 MPa in a vacuum.
Spark plasma sintering was performed at 0 ° C. for 5 minutes and 60 minutes. Thus, a sintered body of the low thermal expansion heat-resistant alloy of the present invention was obtained. These sintered bodies were processed into a predetermined shape to prepare a test piece for strength evaluation.

For each of the alloys obtained in this example (sintering time: 5 minutes and 60 minutes), room temperature (2 minutes)
8 ° C), 400 ° C, 500 ° C, 600 ° C and 700 ° C
The 0.2% proof stress was measured in each of. FIG. 1 shows the measurement results. FIG. 1 shows a temperature-strength characteristic relationship of an alloy (comparative example) corresponding to the composition of the age hardening type controlled expansion alloy disclosed in Japanese Patent Application Laid-Open No. 4-1057. As can be seen from the graph of FIG. 1, the low-thermal-expansion heat-resistant alloy of the present invention has a sintering time of 600 ° C. for both 5 minutes and 60 minutes.
A strength of about 1200 MPa or more was maintained up to that point, and particularly when the sintering time was 60 minutes, a strength of about 900 MPa could be maintained even at 700 ° C.

When the coefficient of thermal expansion of the heat-resistant alloy with low thermal expansion of this embodiment at each temperature was measured, it was found to be 8 to 11 ×
It was in the range of 10 ^-6 / ° C. FIG. 2 shows an example of a TEM photograph showing the structure of the low-thermal-expansion heat-resistant alloy of this example. By TEM observation, it was confirmed that the precipitate particles (NbC, etc.) were uniformly and finely dispersed at the grain boundaries of the parent phase composed of crystal grains having an average particle diameter of 1 μm or less. FIG. 3 shows the results of X-ray diffraction of each of the alloys (sintering times: 5 minutes and 60 minutes) obtained in this example. It can be seen that in the case of sintering for 60 minutes, the peak of carbide is more remarkable and sharp. (Example 4) After sintering the mixed powder of Example 1 under the same conditions as in Example 1, the obtained sintered body was rapidly cooled from its sintering temperature by cooling with argon gas. The cooling rate at this time was about 20 ° C./min or more. Thereby, the 0.2% proof stress at 700 ° C. of the sintered body of the present example is about 820 MPa.
Met. (Example 5) After sintering the mixed powder of Example 1 under the same conditions as in Example 1, the temperature was lowered from the sintering temperature by argon gas cooling.
The sintered body was rapidly cooled to 00 ° C. or lower, further heated to 750 ° C., and subjected to hot forging. Thus, the 0.2% proof stress at 700 ° C. of the sintered body of the present example is about 950 MPa
Met. (Example 6) After sintering the mixed powder of Example 1 under the same conditions as in Example 1, the sintered powder was cooled from the sintering temperature by argon gas cooling.
It was rapidly cooled to 00 ° C. or lower, and further subjected to aging treatment at 750 ° C. for 10 hours. Thereby, 700 of the sintered body of the present example was obtained.
The 0.2% proof stress at ° C. was about 1020 MPa. (Example 7) After sintering the mixed powder of Example 2 under the same conditions as in Example 2, the sintered body is subjected to a solution treatment at 1000 ° C for 2 hours, and further sintered from 1000 ° C by water quenching. The body was quenched below 100 ° C. Then, at 800 ° C, 1
A 0 hour aging treatment was performed. As a result, the 0.2% proof stress at 700 ° C. of the sintered body of this example is about 1030 MPa
a. (Example 8) After sintering the mixed powder of Example 2 under the same conditions as in Example 2, the sintered body was subjected to a solution treatment at 950 ° C for 2 hours, and further sintered at 950 ° C by cooling with argon gas. The body was quenched. Thereafter, hot forging was performed at 850 ° C. Thereby, the 0.2% proof stress at 700 ° C. of the sintered body of this example was about 1070 MPa.

[0047]

According to the present invention, nickel is 20 to 50%, cobalt is 25% or less, and niobium is 5 to 15% by weight.
%, Titanium 2-10%, at least one of aluminum and silicon 1% or less, carbon 0.2-2.0%, the balance being iron and unavoidable impurities, the strength of which is 1000 MPa or more at room temperature. And 600 ° C
In addition, a low-heat-expansion heat-resistant alloy having a strength of 800 MPa or more and a thermal expansion coefficient from room temperature to 600 ° C. of 12 × 10 ⁻⁶ / ° C. or less can be provided.

As a method for producing the low thermal expansion heat-resistant alloy of the present invention, it is particularly preferable to employ a powder metallurgy method instead of a conventional casting method, whereby a long-time solution treatment or aging conventionally performed. Processing can be omitted, and a low-thermal-expansion heat-resistant alloy having high strength characteristics and a low thermal expansion coefficient as described above can be provided with improved production efficiency. In particular, when the crystal grain size having the above alloy composition is 5
μm or less, more preferably 1 μm or less, and prepare the mixed powder in a non-oxidizing atmosphere at 900 ° C. to 1 ° C.
In the case of sintering at a sintering temperature of 300 ° C., the crystal grain size of the mother phase of the obtained alloy becomes fine, and a low-thermal-expansion heat-resistant alloy having the above characteristics can be stably manufactured.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between 0.2% proof stress and temperature of a low thermal expansion heat-resistant alloy according to an embodiment of the present invention.

FIG. 2 shows TE of a low thermal expansion heat-resistant alloy according to an embodiment of the present invention.
It is a copy of an M photograph.

FIG. 3 is an X-ray diffraction chart of a low thermal expansion heat-resistant alloy according to an example of the present invention.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B22F 3/105 B22F 3/105 3/14 3/14 D 3/24 3/24 BE EC21D 6/00 101 C21D 6/00 101A C22C 38/14 C22C 38/14 F term (reference) 4K018 AA30 AB07 AC01 BA03 BA04 BA08 BA20 BC16 DA21 DA31 EA02 EA22 EA31 EA46 FA08 KA07 KA70

Claims (21)

[Claims] 1% by weight of nickel 20 to 50%, cobalt 25% or less, niobium 5 to 15%, titanium 2 to 10
%, At least one of aluminum and silicon 1%
Hereinafter, it has a composition of 0.2 to 2.0% carbon, the balance being iron and inevitable impurities, and a strength at room temperature of 1000M.
The strength at 600 ° C. is 800 MPa or more at Pa or higher, and the coefficient of thermal expansion from room temperature to 600 ° C. is 12 × 10
A low thermal expansion heat-resistant alloy characterized by having a temperature of ^-6 / ° C or less. 2. The alloy has an average crystal grain size of 5 μm or less,
The low thermal expansion heat resistant alloy according to claim 1, wherein the thickness is more preferably 1 µm or less. 3. The low thermal expansion heat-resistant alloy according to claim 1, wherein the alloy contains a precipitate of an intermetallic compound and a carbide which are elements constituting the alloy composition. 4. Nickel 20 to 50%, cobalt 25% or less, niobium 5 to 15%, titanium 2 to 10% by weight
%, At least one of aluminum and silicon 1%
Hereinafter, the method includes a step of preparing a mixed powder so as to have a composition of 0.2 to 2.0% carbon and the balance being iron and unavoidable impurities, and a step of sintering the mixed powder. Manufacturing method of low thermal expansion heat resistant alloy. 5. The method according to claim 4, wherein the mixed powder is prepared by a mechanical alloying method or a mechanical milling method, and has a crystal grain size of 1 μm or less. 6. The method according to claim 4, wherein the mixed powder is sintered at a sintering temperature of 900 to 1300 ° C. 7. The method for producing a heat-resistant alloy with low thermal expansion according to claim 4, wherein the mixed powder is produced by a mechanical milling method using an alloy powder having the alloy composition as a raw material. Method. 8. The low thermal expansion according to claim 4, wherein the mixed powder is produced by a mechanical alloying method using a powder of each element constituting the alloy composition as a raw material. Manufacturing method of heat-resistant alloy. 9. The mixed powder is manufactured by a mechanical alloying method using at least two or more alloy powders of the elements constituting the alloy composition and powders of the remaining individual elements as raw materials. Item 7. The method for producing a low thermal expansion heat-resistant alloy according to any one of Items 4 to 6. 10. The method according to claim 9, wherein the alloy powder is an iron-nickel-cobalt alloy powder. 11. The method according to claim 9, wherein the alloy powder contains at least one of titanium carbide, niobium carbide and cobalt carbide. 12. The mixed powder comprises at least one hydride powder of the elements constituting the alloy composition and powder of the remaining individual elements or at least two or more alloy powders of the elements constituting the alloy composition. The method for producing a low thermal expansion heat-resistant alloy according to any one of claims 4 to 6, wherein the alloy is produced by a mechanical alloying method using the remaining powders of the individual elements as raw materials. 13. The method according to claim 12, wherein the hydride is heptane or another hydrocarbon. 14. The method according to claim 12, wherein the hydride is titanium hydride. 15. The method according to claim 4, wherein the mixed powder is sintered by spark plasma sintering, hot press sintering, or metal powder injection sintering. Manufacturing method of low thermal expansion heat resistant alloy. 16. The method according to claim 4, wherein after sintering the mixed powder, the obtained sintered body is rapidly cooled from a sintering temperature. . 17. The method for producing a low thermal expansion heat-resistant alloy according to claim 16, wherein after rapidly cooling the sintered body, the sintered body is subjected to hot working at a predetermined temperature. 18. The method for producing a low thermal expansion heat-resistant alloy according to claim 16, wherein after rapidly cooling the sintered body, the sintered body is subjected to an aging treatment at a predetermined temperature. 19. After sintering the mixed powder, the obtained sintered body is subjected to a solution treatment at a first heat treatment temperature, and the sintered body is rapidly cooled from the first heat treatment temperature. The aging treatment is performed at a temperature.
The method for producing a low thermal expansion heat-resistant alloy according to any one of the above. 20. After sintering the mixed powder, the obtained sintered body is subjected to a solution treatment at a first heat treatment temperature, and the sintered body is rapidly cooled from the first heat treatment temperature. The hot working is performed at a temperature.
The method for producing a low thermal expansion heat-resistant alloy according to any one of the above. 21. 20% by weight of nickel, 25% or less of cobalt, 5% to 15% of niobium, 2% to 10% of titanium by weight%.
%, At least one of aluminum and silicon 1%
Hereinafter, a mixed powder having a composition of 0.2 to 2.0% carbon and a balance of iron and unavoidable impurities and having a crystal grain size of 5 μm or less is prepared, and the mixed powder is mixed in a non-oxidizing atmosphere at 900 ppm.
A low-thermal-expansion heat-resistant alloy produced by sintering at a sintering temperature of 1C to 1300C.