A multimodal [gamma] apos; reinforced cobalt-nickel-based superalloy and preparation method thereof

Abstract

The invention discloses a multi-peak gamma'reinforced cobalt-nickel-based high-temperature alloy and a preparation method thereof, and belongs to the technical field of cobalt-based high-temperature alloys. According to the multi-peak gamma'reinforced cobalt-nickel-based high-temperature alloy disclosed by the invention, alloy components are optimized, and Mo and Ta alloy elements are introduced to adjust Gibbs free energy precipitated from a primary gamma 'phase and a secondary gamma' phase, so that the multi-peak gamma 'reinforced cobalt-nickel-based high-temperature alloy comprises a gamma matrix, the primary gamma' phase and the secondary gamma 'phase in phase composition; and enough mechanical properties are provided for long-term service of the alloy.

Description

Technical Field

[0001] The invention belongs to the technical field of cobalt-based high-temperature alloys, and in particular relates to a multi-peak γ′-strengthened cobalt-nickel-based high-temperature alloy and a preparation method thereof. Background Art

[0002] High-temperature alloys are a type of structural material based on iron, cobalt and nickel that can serve in high-temperature environments above 600°C and withstand harsh alternating loads. Because of its excellent high-temperature strength, thermal fatigue resistance, creep resistance, castability and wear resistance at high temperatures, it is very suitable as a key material for hot-end components of high-end equipment such as aircraft engines, large-size blades of heavy-duty ground gas turbines and turbine guide vanes.

[0003] The new cobalt-based superalloys significantly improve the high-temperature mechanical properties of the alloys by precipitation strengthening and coherent strengthening of the γ′ phase coherent with the matrix. The size and morphology of the γ′ phase directly determine the high-temperature mechanical properties of the alloys. The change of alloy composition will directly affect the size and morphology of the γ′ phase, but the γ′ phase region of cobalt-based superalloys is narrow and the ability of alloying regulation is limited. In order to meet the performance requirements of high-temperature service, the size and morphology of the γ′ phase of the alloy can be regulated by heat treatment. The primary γ′ phase precipitated during the solution treatment has been the focus of previous research. With the continuous improvement of the dislocation pair coupling mechanism, the secondary γ′ phase precipitated during the aging treatment has also received widespread attention. The size of the γ′ phase will directly affect the mechanism of dislocation pair passing through the γ′ phase. When facing uniformly distributed fine γ′ phase dislocations, they will pass through with a weak dislocation pair coupling mechanism, while when facing larger γ′ phase dislocations, they will pass through with an Orowan bypass or strong dislocation pair coupling mechanism.

[0004] Therefore, how to regulate the distribution and size of the multi-peak γ′ phase under limited alloying conditions and combine it with heat treatment process to obtain better mechanical properties of the alloy is an important topic that needs to be studied urgently. Summary of the invention

[0005] The object of the present invention is to provide a multi-modal γ′ strengthened cobalt-nickel based high temperature alloy and a preparation method thereof, so as to solve the technical problem that the existing methods are difficult to achieve the regulation of the distribution and size of the multi-modal γ′ phase.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] The invention discloses a multi-peak γ′ strengthened cobalt-nickel-based high-temperature alloy, which comprises, in atomic percentage, 8.0-9.0% Al, 25.0-40.0% Ni, 3.0-4.0% Ti, 2.0-4.0% W, 2.0-4.0% Mo, 1.0-2.0% Ta, and the remainder is Co and unavoidable impurities, and the sum of the atomic percentages of the above components is 100%.

[0008] Furthermore, the content of the unavoidable impurities is no more than 0.1%.

[0009] The present invention also discloses a method for preparing the multi-peak γ′ strengthened cobalt-nickel based high temperature alloy, comprising the following steps:

[0010] According to the atomic percentage, pure metal Co, pure metal Al, pure metal Ni, pure metal Ti, pure metal Mo, pure metal Ta and cobalt-tungsten alloy are weighed to prepare alloy raw materials;

[0011] The alloy raw material is subjected to arc melting treatment to obtain an alloy ingot;

[0012] The alloy ingot is subjected to a solid solution treatment to obtain a solid solution ingot;

[0013] The solid solution cast ingot is subjected to aging treatment to obtain a multi-peak γ′ strengthened cobalt-nickel based high temperature alloy.

[0014] Furthermore, the process of arc melting the alloy raw material is as follows:

[0015] The alloy raw materials are placed in a container in a vacuum arc melting furnace, a titanium block is placed in the empty space of the container, and after the required vacuum degree is reached, argon gas is introduced;

[0016] The position of the container is adjusted so that the arc gun faces the metal titanium block, the distance between the arc gun and the metal titanium block is adjusted, and arc striking is started. After arc striking is successful, the metal titanium block is melted;

[0017] Adjust the position of the container so that the alloy raw material is facing the arc gun. After adjusting the arc gun to a suitable distance from the alloy raw material, start to strike the arc. After the arc is successfully struck, gradually increase the arc current and use a magnetic stirrer to fully mix the alloy raw materials. After smelting is completed, an alloy ingot is obtained.

[0018] Furthermore, the specific process of evacuating to the required vacuum degree is:

[0019] Place the alloy raw materials into the container in the vacuum arc melting furnace, and place the titanium block in the empty container. After completion, start to evacuate the vacuum and introduce argon gas for washing. After low vacuum is drawn again, introduce argon gas for secondary washing. Then, low vacuum is drawn again, and then the molecular pump is turned on to evacuate the high vacuum until the high vacuum degree is less than 4*10 -3 Pa, argon gas is introduced into the smelting furnace again;

[0020] Among them, low vacuum must ensure that the air pressure in the melting furnace is less than -0.1MPa, and argon gas is introduced until the air pressure in the melting furnace chamber reaches 0.06MPa.

[0021] Furthermore, in the cobalt-tungsten alloy, Co:W=3:2 in atomic percentage.

[0022] Furthermore, the distance between the arc gun and the titanium block is 1-2 mm; the arc current is set to 50 A before starting the arc, and after the arc is successfully started, the arc current is increased to 100 A and 200 A respectively to completely melt the titanium;

[0023] After the arc is successfully struck, the arc gun is raised to 15 cm, and the arc current is increased to 100 A while the arc gun is rotated forward at a rotation speed of 5.0° / s; the arc current is increased to 200 A while the magnetic stirring device is turned on, and the current of the magnetic stirring device is set not to exceed 5 A, and then the arc current is increased to 500 A. The melting is carried out for not less than 1 min. After each melting is completed, the sample is turned over and melted again. After repeating the melting several times, the alloy ingot is obtained after cooling.

[0024] Furthermore, the smelting was repeated 8 times.

[0025] Furthermore, the process parameters of the solution treatment are: the solution treatment temperature is 1250°C, the heating rate is 5-10°C / min below 1000°C, the heating rate is 3-5°C / min above 1000°C, the holding time is 10h, the cooling method is water cooling, and the cooling rate is not less than 300-350°C / min.

[0026] Furthermore, the process parameters of the aging treatment are: temperature of 900-1000°C, heating rate of 5-10°C / min, holding time of 100h, cooling method of air cooling, and cooling rate in the range of 100-150°C / min.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The invention discloses a multi-modal γ′ strengthened cobalt-nickel-based high-temperature alloy. The alloy composition is optimized and Mo and Ta alloy elements are introduced to adjust the Gibbs free energy of precipitation of primary γ′ phase and secondary γ′ phase. The multi-modal γ′ strengthened cobalt-nickel-based high-temperature alloy includes a γ matrix, a primary γ′ phase and a secondary γ′ phase in terms of phase composition. The multi-modal γ′ phase can provide more dislocation hindering sites and more dislocation pair coupling mechanisms, thereby providing sufficient mechanical properties for the long-term service of the alloy.

[0029] The present invention also discloses a method for preparing the above-mentioned multi-peak γ′ strengthened cobalt-nickel based high-temperature alloy, by sequentially subjecting the alloy raw materials to arc melting treatment, solution treatment and aging treatment, and by regulating the cooling rate of the solution treatment as well as the temperature and cooling rate of the aging treatment, the precipitation behavior of the multi-peak γ′ phase is regulated from the aspects of diffusion thermodynamics and kinetics, which significantly solves the problem that the existing regulation methods are difficult to effectively achieve uniform distribution of the secondary γ′ phase in the γ matrix, and has broad application prospects.

[0030] Furthermore, the method dissolves the coarse primary γ′ phase at the grain boundaries during the casting process through solution treatment, makes the re-precipitated γ′ phase small in size and evenly distributed through water cooling, and then further regulates the size and volume fraction of the γ′ phase through aging treatment, and finally forms a multi-peak γ′ phase during air cooling; the multi-peak γ′ phase makes the coupling mechanism of dislocation pair cutting of the γ′ phase richer, while providing more γ / γ′ phase interfaces, increasing dislocation pinning sites, and providing sufficient mechanical properties for the long-term service of the alloy. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The SEM image of the microstructure of the alloy ingot after solution treatment of the present invention;

[0032] Figure 2 The microstructure morphology of the multi-peak γ′ strengthened cobalt-nickel-based high-temperature alloy of the present invention;

[0033] Figure 3 A statistical diagram of the multi-peak γ′ phase size of the multi-peak γ′ strengthened cobalt-nickel based high temperature alloy of the present invention;

[0034] Figure 4 This is a graph showing the change in yield strength of the multi-peak γ′-strengthened cobalt-nickel-based high-temperature alloy of the present invention with temperature. DETAILED DESCRIPTION

[0035] In order to enable those skilled in the art to understand the characteristics and effects of the present invention, the following is a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used in the text are the common meanings understood by those skilled in the art for the present invention. In the event of a conflict, the definition in this specification shall prevail.

[0036] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0037] Herein, all features such as values, quantities, contents and concentrations defined in the form of numerical ranges or percentage ranges are for simplicity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to have included and specifically disclosed all possible sub-ranges and individual values ​​within the range (including integers and fractions).

[0038] In this document, unless otherwise specified, “includes,” “including,” “contains,” “has,” or similar terms cover the meanings of “consisting of” and “mainly consisting of,” for example, “A includes a” covers the meanings of “A includes a and other” and “A only includes a.”

[0039] In this document, in order to make the description concise, not all possible combinations of various technical features in various embodiments or examples are described. Therefore, as long as there is no contradiction in the combination of these technical features, the various technical features in various embodiments or examples can be combined arbitrarily, and all possible combinations should be considered to be within the scope of this specification.

[0040] The present invention provides a multi-peak γ′ strengthened cobalt-nickel-based high-temperature alloy, which comprises, in atomic percentage, 8.0-9.0% Al, 25.0-40.0% Ni, 3.0-4.0% Ti, 2.0-4.0% W, 2.0-4.0% Mo, 1.0-2.0% Ta, and the remainder is Co and unavoidable impurities, and the sum of the atomic percentages of the above components is 100%;

[0041] Among them, the content of inevitable impurities is not more than 0.1%.

[0042] The present invention also discloses a method for preparing the multi-peak γ′ strengthened cobalt-nickel based high temperature alloy, comprising the following steps:

[0043] S1: Calculate and weigh the amount of each metal raw material according to the atomic percentage of pure metal Co, pure metal Al, pure metal Ni, pure metal Ti, pure metal Mo, pure metal Ta and cobalt-tungsten alloy;

[0044] S2: placing the prepared alloy raw materials into a crucible in a vacuum arc melting furnace, placing a metal titanium block in the empty space of the crucible, pumping to the required vacuum degree, and then introducing argon gas;

[0045] S3: adjusting the position of the crucible so that the arc gun faces the metal titanium block, adjusting the distance between the arc gun and the metal titanium block, starting arcing, and melting the metal titanium block after arcing is successful;

[0046] S4: Adjust the position of the crucible so that the sample is facing the arc gun, adjust the arc gun to a suitable distance from the metal raw material and start striking the arc. After the arc is struck successfully, gradually increase the arc current and use a magnetic stirrer to fully mix the raw materials. After the smelting is completed, an alloy ingot is obtained;

[0047] S5: performing solid solution treatment on the alloy ingot in a box furnace to obtain a solid solution ingot.

[0048] S6: Performing aging treatment on the solution cast ingot in a box furnace to obtain the multi-peak γ′ strengthened cobalt-nickel based high temperature alloy.

[0049] Preferably, in S1, the cobalt-tungsten alloy composition is selected to be Co:W=3:2 in mass percentage.

[0050] Furthermore, S2 includes the following steps: placing the configured alloy raw materials into a crucible in a vacuum arc melting furnace, placing a metal titanium block in the empty crucible position, starting to evacuate after the loading is completed, and passing high-purity argon gas for gas washing; after low vacuum is drawn again, high-purity argon gas is passed for secondary gas washing. After the gas washing step is completed, low vacuum is drawn again, and then the molecular pump is turned on to evacuate high vacuum until the vacuum gauge shows a high vacuum degree of less than 4*10 -3 Pa, and then high-purity argon gas is introduced into the furnace chamber again to 0.08MPa;

[0051] Among them, the low vacuum needs to ensure that the gas pressure in the furnace is less than -0.1MPa, and high-purity argon gas is introduced until the gas pressure in the furnace chamber reaches 0.08MPa.

[0052] Preferably, in S3 and S4, the distance between the arc gun and the metal titanium block is adjusted to 1-2 mm; the arc current is set to 50 A before starting the arc; after the arc is successfully started, the arc current is increased to 100 A and 200 A respectively to completely melt the metal titanium.

[0053] Furthermore, in S4, after the arc is successfully struck, the arc gun is raised to 15 cm, and the arc current is increased to 100 A while the arc gun is rotated forward at a rotation speed of 5.0° / s; the arc current is increased to 200 A while the magnetic stirring device is turned on, and the magnetic stirring current is set to 5 A; the arc current is increased to 500 A, and the smelting time is not less than 1 min.

[0054] Furthermore, in S4, in order to ensure uniform mixing of the components, the sample needs to be turned over and melted again after each smelting, and an alloy ingot is obtained after cooling;

[0055] After one smelting is completed, the sample is turned over by the push rod and smelted again. Each sample needs to be smelted 8 times. After smelting is completed, it is necessary to wait for the alloy ingot to cool down to room temperature, open the inflation valve, and open the furnace door after the air pressure in the furnace chamber returns to atmospheric pressure.

[0056] Furthermore, in S5, the temperature of the solution treatment is 1250°C, the heating rate below 1000°C is 10°C / min, the heating rate above 1000°C is 5°C / min, the holding time is 10h, high-temperature furnace sampling is required, the cooling method is water cooling, and the cooling rate is not less than 300-350°C / min.

[0057] Furthermore, in S6, the temperature of the aging treatment is 900°C, the heating rate is 10°C / min, the holding time is 100h, high-temperature furnace sampling is required, the cooling method is air cooling, the temperature is measured by a thermocouple, and the cooling rate is in the range of 100-150°C / min.

[0058] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0059] The following examples use conventional instruments and equipment in the art. The experimental methods in the following examples where specific conditions are not specified are usually carried out under conventional conditions or under conditions recommended by the manufacturer. The various raw materials used in the following examples are conventional commercial products unless otherwise specified, and their specifications are conventional specifications in the art. In the specification of the present invention and the following examples, unless otherwise specified, "%" means weight percentage, "part" means weight part, and ratio means weight ratio.

[0060] Example 1

[0061] A method for preparing a multi-modal γ′ strengthened cobalt-nickel based high temperature alloy comprises the following steps:

[0062] S1: Pure metal Co, pure metal Al, pure metal Ni, pure metal Ti, pure metal Mo, pure metal Ta and cobalt-tungsten alloy are respectively weighed and configured according to the atomic percentage according to the design component control requirements: Al: 9.0%, Ni: 30.0%, Ti: 4.0%, W: 2.0%, Mo: 2.0%, Ta: 1.0%, and the balance is Co and unavoidable impurities. Ethanol and ultrasonic cleaning instrument are used to remove grease and pollutants on the surface of the raw materials;

[0063] S2: Place the alloy raw materials into the crucible in the vacuum arc melting furnace, place the titanium block in the empty crucible, start vacuuming after loading, and when the vacuum is reduced to -0.1MPa, introduce high-purity argon gas to -0.08MPa for gas washing; pump down to -0.1MPa again and then turn on the molecular pump to pump high vacuum until the high vacuum degree is less than 4*10 -3 Pa, and then high-purity argon gas is introduced into the furnace chamber again to -0.07MPa;

[0064] S3: Adjust the crucible so that the titanium block faces the arc gun (tungsten electrode), adjust the distance between the arc gun and the titanium block to 1mm, set the arc current to 50A and start arcing. After the arc is successfully struck, melt the titanium block. The molten titanium will further absorb the oxygen in the furnace chamber to ensure the purity of the atmosphere in the furnace chamber.

[0065] S4: Adjust the crucible so that the sample is facing the arc gun (tungsten electrode), adjust the distance between the arc gun and the sample to 1-2mm, set the arc current to 50A and start arcing; after arcing is successful, increase the arc current and use a magnetic stirrer to fully mix the raw materials. To ensure that the components are evenly mixed, turn the sample over and melt it again after each smelting, and obtain an alloy ingot after cooling;

[0066] S5: placing the alloy ingot in a box furnace, solution treating at 1250°C for 10h, sampling at high temperature and cooling in cold water to obtain a solution ingot; the heating rate below 1000°C is 10°C / min, the heating rate above 1000°C is 5°C / min, and the cooling rate is 350°C / min;

[0067] S6: The solution ingot is placed in a box furnace and aged at 900°C for 100 h. The high-temperature sample is taken and cooled in air. The temperature is measured with a thermocouple. The heating rate is 10°C / min and the cooling rate is in the range of 100-°C / min to obtain a multi-peak γ′-strengthened cobalt-nickel-based high-temperature alloy.

[0068] Example 2

[0069] A method for preparing a multi-modal γ′ strengthened cobalt-nickel based high temperature alloy comprises the following steps:

[0070] S1: Pure metal Co, pure metal Al, pure metal Ni, pure metal Ti, pure metal Mo, pure metal Ta and cobalt-tungsten alloy are respectively weighed and configured according to the atomic percentage according to the design component control requirements: Al: 9.0%, Ni: 30.0%, Ti: 4.0%, W: 2.0%, Mo: 2.0%, Ta: 2.0%, and the balance is Co and unavoidable impurities. Ethanol and ultrasonic cleaning instrument are used to remove grease and pollutants on the surface of the raw materials;

[0071] S2: Place the alloy raw materials into the crucible in the vacuum arc melting furnace, place the titanium block in the empty crucible, start vacuuming after loading, and when the vacuum is reduced to -0.1MPa, introduce high-purity argon gas to -0.08MPa for gas washing; pump down to -0.1MPa again and then turn on the molecular pump to pump high vacuum until the high vacuum degree is less than 4*10 -3 Pa, and then high-purity argon gas is introduced into the furnace chamber again to -0.07MPa;

[0072] S3: Adjust the crucible so that the titanium block faces the arc gun (tungsten electrode), adjust the distance between the arc gun and the titanium block to 1mm, set the arc current to 50A and start arcing. After the arc is successfully struck, melt the titanium block. The molten titanium will further absorb the oxygen in the furnace chamber to ensure the purity of the atmosphere in the furnace chamber.

[0073] S4: Adjust the crucible so that the sample is facing the arc gun (tungsten electrode), adjust the distance between the arc gun and the sample to 1-2mm, set the arc current to 50A and start arcing; after arcing is successful, increase the arc current and use a magnetic stirrer to fully mix the raw materials. To ensure that the components are evenly mixed, turn the sample over and melt it again after each smelting, and obtain an alloy ingot after cooling;

[0074] S5: placing the alloy ingot in a box furnace, solution treating at 1250°C for 10h, sampling at high temperature and cooling in cold water to obtain a solution ingot; the heating rate below 1000°C is 10°C / min, the heating rate above 1000°C is 5°C / min, and the cooling rate is 350°C / min;

[0075] S6: Place the solution ingot in a box furnace and age it at 900°C for 100h. Take samples at high temperature and cool them in air. Measure the temperature with a thermocouple. The heating rate is 10°C / min and the cooling rate is within the range of 150°C / min to obtain a multi-peak γ′-strengthened cobalt-nickel-based high-temperature alloy.

[0076] Example 3

[0077] A method for preparing a multi-modal γ′ strengthened cobalt-nickel based high temperature alloy comprises the following steps:

[0078] S1: Pure metal Co, pure metal Al, pure metal Ni, pure metal Ti, pure metal Mo, pure metal Ta and cobalt-tungsten alloy are respectively weighed and configured according to the atomic percentage according to the design component control requirements: Al: 9.0%, Ni: 30.0%, Ti: 4.0%, W: 2.0%, Mo: 4.0%, Ta: 1.0%, and the balance is Co and unavoidable impurities. Ethanol and ultrasonic cleaning instrument are used to remove grease and pollutants on the surface of the raw materials;

[0079] S2: Place the alloy raw materials into the crucible in the vacuum arc melting furnace, place the titanium block in the empty crucible, start vacuuming after loading, and when the vacuum is reduced to -0.1MPa, introduce high-purity argon gas to -0.08MPa for gas washing; pump down to -0.1MPa again and then turn on the molecular pump to pump high vacuum until the high vacuum degree is less than 4*10 -3 Pa, and then high-purity argon gas is introduced into the furnace chamber again to -0.07MPa;

[0080] S3: Adjust the crucible so that the titanium block faces the arc gun (tungsten electrode), adjust the distance between the arc gun and the titanium block to 2 mm, set the arc current to 50A and start arcing. After the arc is successfully struck, melt the titanium block. The molten titanium will further absorb the oxygen in the furnace chamber to ensure the purity of the atmosphere in the furnace chamber.

[0081] S4: Adjust the crucible so that the sample is facing the arc gun (tungsten electrode), adjust the distance between the arc gun and the sample to 1-2mm, set the arc current to 50A and start arcing; after arcing is successful, increase the arc current and use a magnetic stirrer to fully mix the raw materials. To ensure that the components are evenly mixed, turn the sample over and melt it again after each smelting, and obtain an alloy ingot after cooling;

[0082] S5: placing the alloy ingot in a box furnace, solution treating at 1250°C for 10h, sampling at high temperature and cooling in cold water to obtain a solution ingot; the heating rate below 1000°C is 10°C / min, the heating rate above 1000°C is 5°C / min, and the cooling rate is 300°C / min;

[0083] S6: Place the solution ingot in a box furnace and age it at 900°C for 100h. Take samples at high temperature and cool them in air. Measure the temperature with a thermocouple. The heating rate is 10°C / min and the cooling rate is 100°C / min. A multi-peak γ′-strengthened cobalt-nickel-based high-temperature alloy is obtained.

[0084] Example 4

[0085] A method for preparing a multi-modal γ′ strengthened cobalt-nickel based high temperature alloy comprises the following steps:

[0086] S1: Pure metal Co, pure metal Al, pure metal Ni, pure metal Ti, pure metal Mo, pure metal Ta and cobalt-tungsten alloy are respectively weighed and configured according to the atomic percentage according to the design component control requirements: Al: 9.0%, Ni: 30.0%, Ti: 4.0%, W: 2.0%, Mo: 4.0%, Ta: 2.0%, and the balance is Co and unavoidable impurities. Ethanol and ultrasonic cleaning instrument are used to remove grease and pollutants on the surface of the raw materials;

[0087] S2: Place the alloy raw materials into the crucible in the vacuum arc melting furnace, place the titanium block in the empty crucible, start vacuuming after loading, and when the vacuum is reduced to -0.1MPa, introduce high-purity argon gas to -0.08MPa for gas washing; pump down to -0.1MPa again and then turn on the molecular pump to pump high vacuum until the high vacuum degree is less than 4*10 -3 Pa, and then high-purity argon gas is introduced into the furnace chamber again to -0.07MPa;

[0088] S3: Adjust the crucible so that the titanium block faces the arc gun (tungsten electrode), adjust the distance between the arc gun and the titanium block to 2 mm, set the arc current to 50A and start arcing. After the arc is successfully struck, melt the titanium block. The molten titanium will further absorb the oxygen in the furnace chamber to ensure the purity of the atmosphere in the furnace chamber.

[0089] S4: Adjust the crucible so that the sample is facing the arc gun (tungsten electrode), adjust the distance between the arc gun and the sample to 1-2mm, set the arc current to 50A and start arcing; after arcing is successful, increase the arc current and use a magnetic stirrer to fully mix the raw materials. To ensure that the components are evenly mixed, turn the sample over and melt it again after each smelting, and obtain an alloy ingot after cooling;

[0090] S5: placing the alloy ingot in a box furnace, solution treating at 1250°C for 10h, sampling at high temperature and cooling in cold water to obtain a solution ingot; the heating rate below 1000°C is 10°C / min, the heating rate above 1000°C is 5°C / min, and the cooling rate is 300°C / min;

[0091] S6: Place the solution ingot in a box furnace and age it at 900°C for 100h. Take samples at high temperature and cool them in air. Measure the temperature with a thermocouple. The heating rate is 10°C / min and the cooling rate is within the range of 150°C / min to obtain a multi-peak γ′-strengthened cobalt-nickel-based high-temperature alloy.

[0092] Example 5

[0093] A method for preparing a multi-modal γ′ strengthened cobalt-nickel based high temperature alloy comprises the following steps:

[0094] S1: Pure metal Co, pure metal Al, pure metal Ni, pure metal Ti, pure metal Mo, pure metal Ta and cobalt-tungsten alloy are respectively weighed and configured according to the atomic percentage according to the design component control requirements: Al: 9.0%, Ni: 30.0%, Ti: 4.0%, W: 2.0%, Mo: 3.0%, Ta: 1.0%, and the balance is Co and unavoidable impurities. Ethanol and ultrasonic cleaning instrument are used to remove grease and pollutants on the surface of the raw materials;

[0095] S2: Place the alloy raw materials into the crucible in the vacuum arc melting furnace, place the titanium block in the empty crucible, start vacuuming after loading, and when the vacuum is reduced to -0.1MPa, introduce high-purity argon gas to -0.08MPa for gas washing; pump down to -0.1MPa again and then turn on the molecular pump to pump high vacuum until the high vacuum degree is less than 4*10 -3 Pa, and then high-purity argon gas is introduced into the furnace chamber again to -0.07MPa;

[0096] S3: Adjust the crucible so that the titanium block faces the arc gun (tungsten electrode), adjust the distance between the arc gun and the titanium block to 2 mm, set the arc current to 50A and start arcing. After the arc is successfully struck, melt the titanium block. The molten titanium will further absorb the oxygen in the furnace chamber to ensure the purity of the atmosphere in the furnace chamber.

[0097] S4: Adjust the crucible so that the sample is facing the arc gun (tungsten electrode), adjust the distance between the arc gun and the sample to 1-2mm, set the arc current to 50A and start arcing; after arcing is successful, increase the arc current and use a magnetic stirrer to fully mix the raw materials. To ensure that the components are evenly mixed, turn the sample over and melt it again after each smelting, and obtain an alloy ingot after cooling;

[0098] S5: placing the alloy ingot in a box furnace, solution treating at 1250°C for 10h, sampling at high temperature and cooling in cold water to obtain a solution ingot; the heating rate below 1000°C is 10°C / min, the heating rate above 1000°C is 5°C / min, and the cooling rate is 350°C / min;

[0099] S6: Place the solution ingot in a box furnace and age it at 900°C for 100h. Take samples at high temperature and cool them in air. Measure the temperature with a thermocouple. The heating rate is 10°C / min and the cooling rate is 100°C / min. A multi-peak γ′-strengthened cobalt-nickel-based high-temperature alloy is obtained.

[0100] Example 6

[0101] A method for preparing a multi-modal γ′ strengthened cobalt-nickel based high temperature alloy comprises the following steps:

[0102] S1: Pure metal Co, pure metal Al, pure metal Ni, pure metal Ti, pure metal Mo, pure metal Ta and cobalt-tungsten alloy are respectively weighed and configured according to the atomic percentage according to the design component control requirements: Al: 9.0%, Ni: 30.0%, Ti: 4.0%, W: 2.0%, Mo: 4.0%, Ta: 1.0%, and the balance is Co and unavoidable impurities. Ethanol and ultrasonic cleaning instrument are used to remove grease and pollutants on the surface of the raw materials;

[0103] S2: Place the alloy raw materials into the crucible in the vacuum arc melting furnace, place the titanium block in the empty crucible, start vacuuming after loading, and when the vacuum is reduced to -0.1MPa, introduce high-purity argon gas to -0.08MPa for gas washing; pump down to -0.1MPa again and then turn on the molecular pump to pump high vacuum until the high vacuum degree is less than 4*10 -3 Pa, and then high-purity argon gas is introduced into the furnace chamber again to -0.07MPa;

[0104] S3: Adjust the crucible so that the titanium block faces the arc gun (tungsten electrode), adjust the distance between the arc gun and the titanium block to 2 mm, set the arc current to 50A and start arcing. After the arc is successfully struck, melt the titanium block. The molten titanium will further absorb the oxygen in the furnace chamber to ensure the purity of the atmosphere in the furnace chamber.

[0105] S4: Adjust the crucible so that the sample is facing the arc gun (tungsten electrode), adjust the distance between the arc gun and the sample to 1-2mm, set the arc current to 50A and start arcing; after arcing is successful, increase the arc current and use a magnetic stirrer to fully mix the raw materials. To ensure that the components are evenly mixed, turn the sample over and melt it again after each smelting, and obtain an alloy ingot after cooling;

[0106] S5: placing the alloy ingot in a box furnace, solution treating at 1250°C for 10h, sampling at high temperature and cooling in cold water to obtain a solution ingot; the heating rate below 1000°C is 10°C / min, the heating rate above 1000°C is 3°C / min, and the cooling rate is 350°C / min;

[0107] S6: Place the solution ingot in a box furnace and age it at 1000°C for 100h. Take samples at high temperature and cool them in air. Measure the temperature with a thermocouple. The heating rate is 5°C / min and the cooling rate is within the range of 150°C / min to obtain a multi-peak γ′-strengthened cobalt-nickel-based high-temperature alloy.

[0108] The microstructure morphology after solution treatment and aging treatment obtained in Example 1 was characterized by scanning electron microscopy; Figure 1 and Figure 2 The results show that the precisely controlled heat treatment process causes a large number of fine secondary γ′ phases to precipitate in the γ matrix channels of the alloy; Figure 3 It is a frequency distribution histogram obtained by measuring the size of the multi-peak γ′ phase of the alloy in combination with Image pro Plus. It can be seen that the alloy contains both a secondary γ′ phase with an average diameter in the range of 20-100nm and a primary γ′ phase with an average diameter in the range of 350-450nm. Figure 4 The nominal yield strength diagram of the alloy at 0.2% deformation at different temperatures and the comparison with the commercial cobalt-based high-temperature alloy show that the mechanical properties of the multi-peak γ′ phase-strengthened cobalt-nickel-based high-temperature alloy have been significantly improved.

[0109] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A multi-modal γ′ strengthened cobalt-nickel based high temperature alloy, characterized in that: In atomic percentage, the composition include: Al: 8.0-9.0%, Ni: 25.0-40.0%, Ti: 3.0-4.0%, W: 2.0-4.0%, Mo: 2.0-4.0%, Ta: 1.0-2.0%, the remainder is Co and inevitable impurities, and the sum of the atomic percentages of the above components is 100%.

2. A multimodal γ′ strengthened cobalt-nickel based high temperature alloy according to claim 1, characterized in that: The content of the unavoidable impurities is not more than 0.1%.

3. The method for preparing a multi-modal γ′ strengthened cobalt-nickel based high temperature alloy according to claim 1 or 2, characterized in that: The following steps are involved: According to the atomic percentage, pure metal Co, pure metal Al, pure metal Ni, pure metal Ti, pure metal Mo, pure metal Ta and cobalt-tungsten alloy are weighed to prepare alloy raw materials; The alloy raw material is subjected to arc melting treatment to obtain an alloy ingot; The alloy ingot is subjected to a solid solution treatment to obtain a solid solution ingot; The solid solution cast ingot is subjected to aging treatment to obtain a multi-peak γ′ strengthened cobalt-nickel based high temperature alloy.

4. The method for preparing a multi-modal γ′ strengthened cobalt-nickel based high temperature alloy according to claim 3, characterized in that: The process of arc melting the alloy raw material is as follows: The alloy raw materials are placed in a container in a vacuum arc melting furnace, a titanium block is placed in the empty space of the container, and after the required vacuum degree is reached, argon gas is introduced; The position of the container is adjusted so that the arc gun faces the metal titanium block, the distance between the arc gun and the metal titanium block is adjusted, and arc striking is started. After arc striking is successful, the metal titanium block is melted; Adjust the position of the container so that the alloy raw material is facing the arc gun. After adjusting the arc gun to a suitable distance from the alloy raw material, start to strike the arc. After the arc is successfully struck, gradually increase the arc current and use a magnetic stirrer to fully mix the alloy raw materials. After smelting is completed, an alloy ingot is obtained.

5. The method for preparing a multi-modal γ′ strengthened cobalt-nickel based high temperature alloy according to claim 4, characterized in that: The specific process of pumping to the required vacuum degree is: Place the alloy raw materials into the container in the vacuum arc melting furnace, and place the titanium block in the empty container. After completion, start to evacuate the vacuum and introduce argon gas for washing. After low vacuum is drawn again, introduce argon gas for secondary washing. Then, low vacuum is drawn again, and then the molecular pump is turned on to evacuate the high vacuum until the high vacuum degree is less than 4*10 -3 Pa, argon gas is introduced into the smelting furnace again; Among them, low vacuum must ensure that the air pressure in the melting furnace is less than -0.1MPa, and argon gas is introduced until the air pressure in the melting furnace chamber reaches 0.06MPa.

6. The method for preparing a multi-modal γ′ strengthened cobalt-nickel based high temperature alloy according to claim 4, characterized in that: In terms of atomic percentage, in the cobalt-tungsten alloy, Co:W=3:

2.

7. The method for preparing a multi-modal γ′ strengthened cobalt-nickel based high temperature alloy according to claim 4, characterized in that: The distance between the arc gun and the titanium block is 1-2 mm; the arc current is set to 50A before starting the arc, and after the arc is successfully started, the arc current is increased to 100A and 200A respectively to completely melt the titanium; After the arc is successfully struck, the arc gun is raised to 15 cm, the arc current is increased to 100 A, and the arc gun is rotated forward at a speed of 5.0° / s; The arc current was increased to 200 A and the magnetic stirring device was turned on at the same time. The current of the magnetic stirring device was set not to exceed 5 A. The arc current was then increased to 500 A. The smelting was performed for not less than 1 min. After each smelting was completed, the sample was turned over and smelted again. After repeating the smelting several times, the alloy ingot was obtained after cooling.

8. The method for preparing a multi-modal γ′ strengthened cobalt-nickel based high temperature alloy according to claim 7, characterized in that: The melting was repeated 8 times.

9. The method for preparing a multi-modal γ′ strengthened cobalt-nickel based high temperature alloy according to claim 3, characterized in that: The process parameters of the solution treatment are as follows: the solution treatment temperature is 1250°C, the heating rate is 5-10°C / min below 1000°C, the heating rate is 3-5°C / min above 1000°C, the holding time is 10h, the cooling method is water cooling, and the cooling rate is not less than 300-350°C / min.

10. The method for preparing a multi-modal γ′ strengthened cobalt-nickel based high temperature alloy according to claim 3, characterized in that: The process parameters of the aging treatment are: temperature of 900-1000°C, heating rate of 5-10°C / min, holding time of 100h, cooling method of air cooling, and cooling rate in the range of 100-150°C / min.

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