A Ni-Al-Re ternary model single crystal alloy and preparation method thereof

Abstract

The present invention relates to the technical field of alloys, and discloses a Ni‑Al‑Re ternary model single crystal alloy and a preparation method thereof. The preparation method comprises the following steps: Ni, Al and Re are made into a Ni‑Al‑Re ternary alloy, wherein the mass ratio of Al to Ni is 1:10-11; the Ni‑Al‑Re ternary alloy is heated to 1325-1335°C, kept warm for 6-8h, cooled to 1145-1155°C at a rate of 4-6°C / min, and then air-cooled; then heated to 1145-1155°C, kept warm for 7-9h, cooled; then heated to 865-875°C, kept warm for 48-50h, cooled to obtain a Ni‑Al‑Re ternary model single crystal alloy. The Ni‑Al‑Re ternary model single crystal alloy obtained by the preparation method of the present invention has a long high temperature life and can maintain stability for a long time under high temperature and high pressure.

Description

Technical Field

[0001] The present invention relates to the technical field of alloys, and in particular to a Ni-Al-Re ternary model single crystal alloy and a preparation method thereof. Background Art

[0002] Nickel-based single crystal high-temperature alloys are widely used in key components such as aero-engine blades due to their excellent mechanical properties, oxidation resistance and corrosion resistance at extremely high temperatures. As the requirements for material performance of the new generation of aviation and energy equipment continue to increase, especially in terms of the structural stability and durability of the alloy, how to further optimize the microstructure of the alloy through scientific and reasonable preparation and heat treatment methods to improve its high-temperature performance has become an important topic in the field of materials science.

[0003] The use of model alloys is of great significance when studying nickel-based single crystal high-temperature alloys. Since the composition design of model nickel-based single crystal high-temperature alloys is simple and usually contains only a few key elements (such as Ni, Al, and Re), researchers can more clearly understand the influence mechanism of each element on the alloy structure and properties. In addition, the simplified composition design of model alloys also provides more controllable conditions for experimental and theoretical research. In model alloys, the interactions between elements are relatively simple, making the results obtained through experimental observations and data analysis more predictable and reproducible. These research results not only help to reveal the basic working principles of each element in nickel-based alloys, but also provide theoretical guidance for the development of new high-performance alloys.

[0004] The preparation of alloys usually includes smelting and heat treatment processes, among which a suitable heat treatment process can release the internal stress inside the alloy and improve the stability and mechanical properties of the alloy. However, the Ni-Al-Re ternary model single crystal alloy prepared by the existing technology has poor high temperature stability, poor microstructure morphology, and short high temperature life, which is not conducive to the testing of model alloys in high temperature environments. Summary of the invention

[0005] In order to solve the problem that the Ni-Al-Re ternary model single crystal alloy prepared by the existing method has poor microstructure morphology and short high temperature life, the present invention provides a method for preparing a Ni-Al-Re ternary model single crystal alloy. The preparation method can make the prepared Ni-Al-Re ternary model single crystal alloy have a regular microstructure and a long high temperature life, and can maintain stability for a long time under high temperature and high pressure, which is of great significance for the research of basic scientific problems related to nickel-based single crystal high temperature alloys (such as Re element diffusion, microstructure evolution mechanism, etc.).

[0006] The specific technical scheme of the present invention is:

[0007] In a first aspect, the present invention provides a method for preparing a Ni-Al-Re ternary model single crystal alloy, comprising the following steps:

[0008] S1: Ni, Al and Re are made into Ni-Al-Re ternary alloy, wherein the mass ratio of Al to Ni is 1:10~11;

[0009] S2: The Ni-Al-Re ternary alloy is heated to 1325-1335°C, kept at this temperature for 6-8 hours, cooled to 1145-1155°C at a rate of 4-6°C / min, and then air-cooled;

[0010] S3: heating the Ni-Al-Re ternary alloy treated in step S2 to 1145-1155° C., keeping the temperature for 7-9 hours, and then cooling;

[0011] S4: heating the Ni-Al-Re ternary alloy treated in step S3 to 865-875° C., keeping the temperature for 48-50 hours, and cooling the alloy to obtain a Ni-Al-Re ternary model single crystal alloy.

[0012] The present invention sets the mass ratio of Al to Ni in the alloy to 1:10-11, which can make the γ' phase content in the alloy at an appropriate level, thereby giving the alloy better high-temperature stability and a longer high-temperature life. The specific principle is as follows:

[0013] In the Ni-Al-Re ternary model single crystal alloy, Al is mainly used to form the γ' phase (composition is Ni3Al), and a small amount of Al is dissolved in the γ matrix (pure Ni). Assuming that Al is only used to form the γ' phase, the density of Ni at room temperature is 8.90g / cm 3 , the density of Ni3Al is 7.45g / cm 3 . Volume fraction of γ' phase in alloy at room temperature (f γ’ ) is 70%, the high temperature life of the alloy is the longest, so in the present invention, the composition is designed with the volume fraction of the γ' phase being 70% as the target value. The Re element mainly exists in the alloy in the form of solid solution and does not affect the volume fraction of the γ and γ' phases. At this time, the calculation steps of the mass ratio of Ni and Al in the alloy are as follows:

[0014] (1) Calculate the mass fraction of Ni and Ni3Al:

[0015] The relationship between volume fraction and mass fraction can be converted through density, the formula is:

[0016] ,

[0017] Where m is mass, V is volume, and ρ is density.

[0018] Assuming the total volume of Ni and Ni3Al is 1, the masses of Ni and Ni3Al are:

[0019] ,

[0020] .

[0021] (2) Calculate the mass of Ni and Al in Ni3Al:

[0022] The relative atomic mass of Ni is 58.693, the relative atomic mass of Al is 26.982, and the mass proportions of Ni and Al in Ni3Al are:

[0023] ,

[0024] .

[0025] Therefore, the masses of Ni and Al in Ni3Al are:

[0026] ,

[0027] .

[0028] (3) Calculate the total mass of Ni and the total mass of Al:

[0029] The total mass of Ni includes the mass of Ni in Ni3Al and the mass of elemental Ni:

[0030] ;

[0031] The total mass of Al comes only from the aluminum in Ni3Al:

[0032] .

[0033] (4) Calculate the mass ratio of Ni and Al:

[0034] .

[0035] Based on the above nickel-aluminum ratio design, the present invention adopts a specific heat treatment procedure in steps S2 to S4, which can further improve the high temperature stability of the Ni-Al-Re ternary model single crystal alloy and extend its high temperature life. Specifically:

[0036] (1) Design of heat treatment temperature and holding time at each stage:

[0037] In the Ni-Al-Re ternary model single crystal alloy, Re diffuses slowly and has an important influence on the alloy's long-lasting life and creep resistance. The present invention adopts a temperature of 1325~1335°C in step S2, which helps to completely dissolve the primary γ' phase and other Re-rich precipitated phases, eliminate the chemical composition segregation in the cast structure, and create a uniform matrix structure for subsequent heat treatment; and in step S2, by setting the holding time to 6~8h, it can ensure that Re is fully dissolved and begins to distribute in the matrix. In step S3, by setting the heat treatment temperature to 1145~1155°C and the holding time to 7~9h, the dissolution and re-precipitation behavior of γ' can be effectively controlled, which helps to make the final alloy material have an ideal microstructure and phase composition when serving at high temperatures. Due to the low diffusivity of the Re element, it may not be able to completely enter the γ' phase during the heat treatment process of step S3. In step S4 of the present invention, by performing a long-term (48-50h) heat treatment at a relatively low temperature (865-875°C), the Re element can be gradually diffused and evenly distributed, thereby ensuring the regularity of the precipitated phase. In the above manner, the design of the heat treatment temperature and the holding time in each stage of steps S2-S3 of the present invention can effectively extend the high temperature life of the Ni-Al-Re ternary model single crystal alloy. When the temperature or time of any stage is improperly controlled, the high temperature life of the alloy finally obtained will be shortened.

[0038] (2) Design of the degree of cooling in step S2:

[0039] According to thermodynamic analysis, the γ' phase in the Ni-Al-Re ternary model single crystal alloy begins to precipitate from about 1150°C. Slow cooling before this temperature (rate of 4~6°C / min) can effectively control the nucleation of the γ' phase, forming a uniform and ideal initial size and distribution, thereby providing a good organizational basis for subsequent cooling, and at the same time, it can also alleviate the stress concentration caused by the rapid precipitation of the γ' phase, avoid residual stress caused by stress concentration, and improve the service life and fatigue resistance of the alloy. The subsequent air cooling method has a faster cooling rate, which can form γ' phase particles that are not too large or uneven, which is beneficial to improve the strength and high temperature stability of the material. Therefore, the above-mentioned cooling program design is adopted in the present invention to perform specific and precise control on the dissolution and precipitation behavior of the γ' phase in the Ni-Al-Re ternary model single crystal alloy, so that the alloy can have higher high temperature stability; and in the above-mentioned cooling program, when the temperature node (1145~1155°C) of the cooling rate is changed or the cooling rate of the two stages is improperly designed, the high temperature life of the alloy finally obtained will be shortened.

[0040] Preferably, in step S1, the content of Re in the Ni-Al-Re ternary alloy is 2-4wt%.

[0041] Furthermore, in step S1, in the Ni-Al-Re ternary alloy, the mass ratio of Al to Ni is 1:10.2-10.6.

[0042] Preferably, in step S2, the average rate of air cooling is 15-20°C / min.

[0043] Preferably, in step S2, the terminal temperature of the air cooling is 20-30°C.

[0044] Preferably, in steps S3 and S4, the cooling method is air cooling, the average rate is 15-20°C / min, and the terminal temperature is 20-30°C.

[0045] Preferably, the specific process of step S1 includes: mixing and smelting Ni, Al and Re to obtain a master alloy; chopping the master alloy and performing spiral crystal selection to obtain a Ni-Al-Re ternary alloy.

[0046] Furthermore, in step S1, the mixed smelting process is carried out in a vacuum induction melting furnace, and the spiral crystal selection process is carried out in a vacuum high gradient single crystal furnace.

[0047] Preferably, in step S2, the rate of heating to 1325-1335°C is 5-10°C / min.

[0048] Preferably, in step S3, the rate of heating to 1145-1155°C is 5-10°C / min.

[0049] Preferably, in step S4, the rate of heating to 865-875°C is 5-10°C / min.

[0050] In a second aspect, the present invention provides a Ni-Al-Re ternary model single crystal alloy prepared by the preparation method.

[0051] Compared with the prior art, the present invention has the following advantages:

[0052] In the present invention, by designing the ratio between elements and coordinating a special heat treatment procedure, the prepared Ni-Al-Re ternary model single crystal alloy can have a longer high temperature life and can remain stable for a long time under high temperature and high pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 It is the temperature-time curve of the heat treatment process in Example 1 and Example 2.

[0054] Figure 2 This is the microstructural morphology of the Ni-Al-Re ternary model single crystal alloy prepared in Example 1.

[0055] Figure 3 This is the microstructural morphology of the Ni-Al-Re ternary model single crystal alloy prepared in Example 2. DETAILED DESCRIPTION

[0056] The present invention will be further described below in conjunction with the embodiments.

[0057] A method for preparing a Ni-Al-Re ternary model single crystal alloy comprises the following steps:

[0058] S1: Ni, Al and Re are made into a Ni-Al-Re ternary alloy, wherein the mass ratio of Al to Ni is 1:10 to 11. The design of the aluminum-nickel ratio in this step can make the γ' phase content in the alloy at an appropriate level, thereby giving the alloy better performance.

[0059] S2: Heat the Ni-Al-Re ternary alloy to 1325~1335℃, keep it at this temperature for 6~8h, then cool it to 1145~1155℃ at a rate of 4~6℃ / min, and then air cool it. This step designs a specific heat treatment temperature and time for the specific element composition and aluminum-nickel ratio of the Ni-Al-Re ternary alloy, which can fully dissolve the precipitated phase in the alloy, eliminate the chemical composition segregation in the cast structure, and ensure the subsequent heat treatment effect; and by adopting a special cooling program, the dissolution and precipitation behavior of the γ' phase are precisely controlled, which can improve the high-temperature stability of the final alloy.

[0060] S3: The Ni-Al-Re ternary alloy treated in step S2 is heated to 1145-1155°C, kept at this temperature for 7-9 hours, and then cooled. In this step, a specific heat treatment temperature and time are used to form a fine and uniformly distributed γ' phase in the matrix, providing preliminary structural strengthening, which helps the final alloy material to have an ideal microstructure and phase composition when serving at high temperatures.

[0061] S4: The Ni-Al-Re ternary alloy treated in step S3 is heated to 865-875°C, kept at this temperature for 48-50 hours, and then cooled to obtain a Ni-Al-Re ternary model single crystal alloy. The design of the heat treatment temperature and time in this step can allow the low-diffusivity Re element to completely enter the γ' phase, further optimize the size and distribution of the γ' phase, achieve the best cubic degree, and significantly improve the high-temperature durability of the alloy.

[0062] In some specific embodiments, the specific process of step S1 includes: mixing and smelting Ni, Al and Re to obtain a master alloy; and after the master alloy is shredded, spiral crystal selection is performed to obtain a Ni-Al-Re ternary alloy. Optionally or preferably, the mixed smelting process is performed in a vacuum induction melting furnace, and the spiral crystal selection process is performed in a vacuum high gradient single crystal furnace.

[0063] In some specific implementations, in step S1, the content of Re in the Ni-Al-Re ternary alloy is 2-4 wt%.

[0064] In some specific embodiments, in step S2, the rate of heating to 1325-1335°C is 5-10°C / min.

[0065] In some specific embodiments, in step S2, the average rate of air cooling is 15-20°C / min, and the terminal temperature is 20-30°C.

[0066] In some specific embodiments, in step S3, the rate of heating to 1145-1155°C is 5-10°C / min.

[0067] In some specific embodiments, in step S4, the rate of heating to 865-875°C is 5-10°C / min.

[0068] In some specific embodiments, in steps S3 and S4, the cooling method is air cooling, the average rate is 15-20°C / min, and the terminal temperature is 20-30°C.

[0069] The present invention is described below by specific examples. It should be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention. Without departing from the spirit and scope of the inventive concept, changes and advantages that can be thought of by those skilled in the art are included in the present invention, and the attached claims and any equivalents thereof are the protection scope of the present invention.

[0070] Unless otherwise defined, all technical terms and scientific terms used in the present invention have the same meanings as those commonly understood by ordinary technicians in the field to which the present disclosure belongs. Unless otherwise specified, the raw materials and equipment used in the present invention are conventional raw materials and equipment in the field and can be obtained from conventional commercial channels; unless otherwise specified, the methods used in the present invention are conventional methods in the field.

[0071] In the following embodiments and comparative examples, the ternary alloy is expressed in the form of "Ni-xAl-yRe (wt%)", which has the following meaning: the ternary alloy is composed of three elements: Ni, Al and Re, wherein the content of Al element is x wt%, the content of Re element is y wt%, and the content of Ni element is (100-xy) wt%.

[0072] Example 1: Preparation of Ni-8.5Al-2Re (wt%) ternary model single crystal alloy

[0073] The Ni-Al-Re ternary model single crystal alloy of this embodiment is Ni-8.5Al-2Re (wt%), which is prepared according to the following steps:

[0074] S1: According to the content of Ni, Al and Re in the final alloy of 89.5wt%, 8.5wt% and 2wt% respectively, three raw materials of pure Ni, pure Al and pure Re are weighed. Pure Ni, pure Al and pure Re are mixed and smelted in a vacuum induction melting furnace to make a Ni-8.5Al-2Re (wt%) master alloy. Then the master alloy is cut into small pieces, and then placed in a vacuum high gradient single crystal furnace, and a Ni-8.5Al-2Re (wt%) single crystal test bar is prepared by a spiral crystal selection process.

[0075] S2: The Ni-8.5Al-2Re (wt%) single crystal test rod was heated to 1330°C at a rate of 10°C / min, kept at this temperature for 6 hours, cooled to 1150°C at a cooling rate of 5°C / min, and then air-cooled to room temperature (25°C). The average cooling rate during the air cooling process was 20°C / min.

[0076] S3: The Ni-8.5Al-2Re (wt%) single crystal test rod that has completed the treatment in step S2 is heated to 1150°C at a rate of 10°C / min, kept at this temperature for 8 hours, then taken out and air-cooled to room temperature (25°C). The average cooling rate during the air-cooling process is 20°C / min.

[0077] S4: The Ni-8.5Al-2Re (wt%) single crystal test rod after the treatment in step S3 is heated to 870°C at a rate of 10°C / min, kept at this temperature for 48 hours, then taken out and air-cooled to room temperature (25°C). The average cooling rate of the air-cooling process is 20°C / min, and a Ni-8.5Al-2Re (wt%) ternary model single crystal alloy specimen is obtained.

[0078] The temperature-time curve during the heat treatment process of steps S2 to S4 above is shown in Figure 1 .

[0079] The microstructure of the Ni-8.5Al-2Re (wt%) ternary model single crystal alloy sample prepared in this embodiment is as follows: Figure 2 As shown, the volume fraction of the γ' phase in the microstructure is 65%, and the γ' phase presents a high degree of cubicity. According to the test, under the conditions of 950°C and 100MPa, the endurance life (fracture time) of the Ni-8.5Al-2Re (wt%) ternary model single crystal alloy sample obtained in this embodiment is 223.4 hours, showing excellent high temperature endurance performance.

[0080] Example 2: Preparation of Ni-8.5Al-4Re (wt%) ternary model single crystal alloy

[0081] The Ni-Al-Re ternary model single crystal alloy of this embodiment is Ni-8.5Al-4Re (wt%), which is prepared according to the following steps:

[0082] S1: According to the content of Ni, Al and Re in the final alloy of 87.5wt%, 8.5wt% and 4wt% respectively, three raw materials of pure Ni, pure Al and pure Re are weighed. Pure Ni, pure Al and pure Re are mixed and melted in a vacuum induction melting furnace to make a Ni-8.5Al-4Re (wt%) master alloy. Then the master alloy is cut into small pieces, and then placed in a vacuum high gradient single crystal furnace, and a Ni-8.5Al-4Re (wt%) single crystal test bar is prepared by a spiral crystal selection process.

[0083] S2: The Ni-8.5Al-4Re (wt%) single crystal test rod was heated to 1330°C at a rate of 10°C / min, kept at this temperature for 6 hours, cooled to 1150°C at a cooling rate of 5°C / min, and then air-cooled to room temperature (25°C). The average cooling rate during the air cooling process was 20°C / min.

[0084] S3: The Ni-8.5Al-4Re (wt%) single crystal test rod treated in step S2 is heated to 1150°C at a rate of 10°C / min, kept at this temperature for 8 hours, then taken out and air-cooled to room temperature (25°C). The average cooling rate during the air-cooling process is 20°C / min.

[0085] S4: The Ni-8.5Al-4Re (wt%) single crystal test rod after the treatment in step S3 is heated to 870°C at a rate of 10°C / min, kept at this temperature for 48 hours, then taken out and air-cooled to room temperature (25°C). The average cooling rate of the air-cooling process is 20°C / min, and a Ni-8.5Al-4Re (wt%) ternary model single crystal alloy specimen is obtained.

[0086] The temperature-time curve during the heat treatment process of steps S2 to S4 above is shown in Figure 1 .

[0087] The microstructure of the Ni-8.5Al-4Re (wt%) ternary model single crystal alloy sample prepared in this embodiment is as follows: Figure 3 As shown, the volume fraction of the γ' phase in the microstructure is 77%, and the γ' phase presents a high degree of cubicity. According to the test, under the conditions of 950°C and 100MPa, the endurance life (fracture time) of the Ni-8.5Al-4Re (wt%) ternary model single crystal alloy sample obtained in this embodiment is 207.3 hours, showing excellent high temperature endurance performance.

[0088] Example 3: Preparation of Ni-8.5Al-2Re (wt%) ternary model single crystal alloy

[0089] The Ni-Al-Re ternary model single crystal alloy of this embodiment is Ni-8.5Al-2Re (wt%), which is prepared according to the following steps:

[0090] S1: According to the content of Ni, Al and Re in the final alloy of 89.5wt%, 8.5wt% and 2wt% respectively, three raw materials of pure Ni, pure Al and pure Re are weighed. Pure Ni, pure Al and pure Re are mixed and smelted in a vacuum induction melting furnace to make a Ni-8.5Al-2Re (wt%) master alloy. Then the master alloy is cut into small pieces, and then placed in a vacuum high gradient single crystal furnace, and a Ni-8.5Al-2Re (wt%) single crystal test bar is prepared by a spiral crystal selection process.

[0091] S2: The Ni-8.5Al-2Re (wt%) single crystal test rod was heated to 1325°C at a rate of 10°C / min, kept at this temperature for 6 hours, cooled to 1145°C at a cooling rate of 6°C / min, and then taken out and air-cooled to room temperature (25°C). The average cooling rate of the air-cooling process was 20°C / min.

[0092] S3: The Ni-8.5Al-2Re (wt%) single crystal test rod treated in step S2 is heated to 1145°C at a rate of 10°C / min, kept at this temperature for 7 hours, then taken out and air-cooled to room temperature (25°C). The average cooling rate during the air-cooling process is 20°C / min.

[0093] S4: The Ni-8.5Al-2Re (wt%) single crystal test rod after the treatment in step S3 is heated to 865°C at a rate of 10°C / min, kept at this temperature for 48 hours, then taken out and air-cooled to room temperature (25°C). The average cooling rate of the air-cooling process is 20°C / min, and a Ni-8.5Al-2Re (wt%) ternary model single crystal alloy specimen is obtained.

[0094] After testing, under the conditions of 950°C and 100MPa, the endurance life (fracture time) of the Ni-8.5Al-2Re (wt%) ternary model single crystal alloy sample obtained in this embodiment is 175.4 hours, showing excellent high-temperature endurance performance.

[0095] Example 4: Preparation of Ni-8.5Al-2Re (wt%) ternary model single crystal alloy

[0096] The Ni-Al-Re ternary model single crystal alloy of this embodiment is Ni-8.5Al-2Re (wt%), which is prepared according to the following steps:

[0097] S1: According to the content of Ni, Al and Re in the final alloy of 89.5wt%, 8.5wt% and 2wt% respectively, three raw materials of pure Ni, pure Al and pure Re are weighed. Pure Ni, pure Al and pure Re are mixed and smelted in a vacuum induction melting furnace to make a Ni-8.5Al-2Re (wt%) master alloy. Then the master alloy is cut into small pieces, and then placed in a vacuum high gradient single crystal furnace, and a Ni-8.5Al-2Re (wt%) single crystal test bar is prepared by a spiral crystal selection process.

[0098] S2: The Ni-8.5Al-2Re (wt%) single crystal test rod was heated to 1335°C at a rate of 10°C / min, kept at this temperature for 8 hours, cooled to 1155°C at a cooling rate of 4°C / min, and then air-cooled to room temperature (25°C). The average cooling rate during the air cooling process was 20°C / min.

[0099] S3: The Ni-8.5Al-2Re (wt%) single crystal test rod treated in step S2 is heated to 1155°C at a rate of 10°C / min, kept at this temperature for 9 hours, then taken out and air-cooled to room temperature (25°C). The average cooling rate during the air-cooling process is 20°C / min.

[0100] S4: The Ni-8.5Al-2Re (wt%) single crystal test rod after the treatment in step S3 is heated to 875°C at a rate of 10°C / min, kept at this temperature for 50 hours, then taken out and air-cooled to room temperature (25°C). The average cooling rate of the air-cooling process is 20°C / min, and a Ni-8.5Al-2Re (wt%) ternary model single crystal alloy specimen is obtained.

[0101] After testing, under the conditions of 950°C and 100MPa, the endurance life (fracture time) of the Ni-8.5Al-2Re (wt%) ternary model single crystal alloy sample obtained in this embodiment is 187.7 hours, showing excellent high-temperature endurance performance.

[0102] Comparative Example 1: Preparation of Ni-8.5Al-4Re (wt%) ternary model single crystal alloy

[0103] The Ni-Al-Re ternary model single crystal alloy of this comparative example is Ni-8.5Al-4Re (wt%), and the preparation steps are different from those of Example 2 only in that: in this comparative example, the heat treatment temperature in step S2 is changed from 1330°C to 1310°C; the remaining steps are the same as those of Example 2. Specifically, the Ni-8.5Al-4Re (wt%) ternary model single crystal alloy of this comparative example is prepared according to the following steps:

[0104] S1: According to the content of Ni, Al and Re in the final alloy of 87.5wt%, 8.5wt% and 4wt% respectively, three raw materials of pure Ni, pure Al and pure Re are weighed. Pure Ni, pure Al and pure Re are mixed and melted in a vacuum induction melting furnace to make a Ni-8.5Al-4Re (wt%) master alloy. Then the master alloy is cut into small pieces, and then placed in a vacuum high gradient single crystal furnace, and a Ni-8.5Al-4Re (wt%) single crystal test bar is prepared by a spiral crystal selection process.

[0105] S2: The Ni-8.5Al-4Re (wt%) single crystal test rod was heated to 1310°C at a rate of 10°C / min, kept at this temperature for 6 hours, cooled to 1150°C at a cooling rate of 5°C / min, and then air-cooled to room temperature (25°C). The average cooling rate during the air cooling process was 20°C / min.

[0106] S3: The Ni-8.5Al-4Re (wt%) single crystal test rod treated in step S2 is heated to 1150°C at a rate of 10°C / min, kept at this temperature for 8 hours, then taken out and air-cooled to room temperature (25°C). The average cooling rate during the air-cooling process is 20°C / min.

[0107] S4: The Ni-8.5Al-4Re (wt%) single crystal test rod after the treatment in step S3 is heated to 870°C at a rate of 10°C / min, kept at this temperature for 48 hours, then taken out and air-cooled to room temperature (25°C). The average cooling rate of the air-cooling process is 20°C / min, and a Ni-8.5Al-4Re (wt%) ternary model single crystal alloy specimen is obtained.

[0108] After testing, under the conditions of 950°C and 100MPa, the endurance life (fracture time) of the Ni-8.5Al-4Re (wt%) ternary model single crystal alloy sample obtained in this comparative example is 97.2 hours, indicating that its high-temperature endurance performance is worse than that of the alloy sample obtained in Example 2. The reason for this is that the heat treatment temperature in step S2 of this comparative example is too low, and the primary γ' phase and other Re-rich precipitated phases cannot be completely dissolved, making it difficult to create a uniform matrix structure for subsequent heat treatment, resulting in poor subsequent heat treatment effect.

[0109] Comparative Example 2: Preparation of Ni-8.5Al-4Re (wt%) ternary model single crystal alloy

[0110] The Ni-Al-Re ternary model single crystal alloy of this comparative example is Ni-8.5Al-4Re (wt%), and the preparation steps are different from those of Example 2 only in that: in this comparative example, the holding time in step S3 is changed from 8 hours to 6 hours; the remaining steps are the same as those of Example 2. Specifically, the Ni-8.5Al-4Re (wt%) ternary model single crystal alloy of this comparative example is prepared according to the following steps:

[0111] S1: According to the content of Ni, Al and Re in the final alloy of 87.5wt%, 8.5wt% and 4wt% respectively, three raw materials of pure Ni, pure Al and pure Re are weighed. Pure Ni, pure Al and pure Re are mixed and melted in a vacuum induction melting furnace to make a Ni-8.5Al-4Re (wt%) master alloy. Then the master alloy is cut into small pieces, and then placed in a vacuum high gradient single crystal furnace, and a Ni-8.5Al-4Re (wt%) single crystal test bar is prepared by a spiral crystal selection process.

[0112] S2: The Ni-8.5Al-4Re (wt%) single crystal test rod was heated to 1330°C at a rate of 10°C / min, kept at this temperature for 6 hours, cooled to 1150°C at a cooling rate of 5°C / min, and then air-cooled to room temperature (25°C). The average cooling rate during the air cooling process was 20°C / min.

[0113] S3: The Ni-8.5Al-4Re (wt%) single crystal test rod treated in step S2 is heated to 1150°C at a rate of 10°C / min, kept at this temperature for 6 hours, then taken out and air-cooled to room temperature (25°C). The average cooling rate during the air-cooling process is 20°C / min.

[0114] S4: The Ni-8.5Al-4Re (wt%) single crystal test rod after the treatment in step S3 is heated to 870°C at a rate of 10°C / min, kept at this temperature for 48 hours, then taken out and air-cooled to room temperature (25°C). The average cooling rate of the air-cooling process is 20°C / min, and a Ni-8.5Al-4Re (wt%) ternary model single crystal alloy specimen is obtained.

[0115] After testing, under the conditions of 950°C and 100MPa, the endurance life (fracture time) of the Ni-8.5Al-4Re (wt%) ternary model single crystal alloy sample obtained in this comparative example is 142.2 hours, indicating that its high-temperature endurance performance is worse than that of the alloy sample obtained in Example 2. The reason for this is that the heat treatment time in step S3 of this comparative example is too short, which is not conducive to the formation of fine and uniformly distributed γ' phase in the matrix.

[0116] Comparative Example 3: Preparation of Ni-8.5Al-4Re (wt%) ternary model single crystal alloy

[0117] The Ni-Al-Re ternary model single crystal alloy of this comparative example is Ni-8.5Al-4Re (wt%), and the preparation steps are different from those of Example 2 only in that: in this comparative example, the holding time in step S4 is changed from 48 hours to 20 hours; the remaining steps are the same as those of Example 2. Specifically, the Ni-8.5Al-4Re (wt%) ternary model single crystal alloy of this comparative example is prepared according to the following steps:

[0118] S1: According to the content of Ni, Al and Re in the final alloy of 87.5wt%, 8.5wt% and 4wt% respectively, three raw materials of pure Ni, pure Al and pure Re are weighed. Pure Ni, pure Al and pure Re are mixed and melted in a vacuum induction melting furnace to make a Ni-8.5Al-4Re (wt%) master alloy. Then the master alloy is cut into small pieces, and then placed in a vacuum high gradient single crystal furnace, and a Ni-8.5Al-4Re (wt%) single crystal test bar is prepared by a spiral crystal selection process.

[0119] S2: The Ni-8.5Al-4Re (wt%) single crystal test rod was heated to 1330°C at a rate of 10°C / min, kept at this temperature for 6 hours, cooled to 1150°C at a cooling rate of 5°C / min, and then air-cooled to room temperature (25°C). The average cooling rate during the air cooling process was 20°C / min.

[0120] S3: The Ni-8.5Al-4Re (wt%) single crystal test rod treated in step S2 is heated to 1150°C at a rate of 10°C / min, kept at this temperature for 8 hours, then taken out and air-cooled to room temperature (25°C). The average cooling rate during the air-cooling process is 20°C / min.

[0121] S4: The Ni-8.5Al-4Re (wt%) single crystal test rod after the treatment in step S3 is heated to 870°C at a rate of 10°C / min, kept at this temperature for 20 hours, then taken out and air-cooled to room temperature (25°C). The average cooling rate of the air-cooling process is 20°C / min, and a Ni-8.5Al-4Re (wt%) ternary model single crystal alloy specimen is obtained.

[0122] After testing, under the conditions of 950°C and 100MPa, the endurance life (fracture time) of the Ni-8.5Al-4Re (wt%) ternary model single crystal alloy sample obtained in this comparative example is 85.3 hours, indicating that its high-temperature endurance performance is worse than that of the alloy sample obtained in Example 2. The reason for this is that the heat treatment time in step S4 of this comparative example is too short. Since Re diffuses slowly in the Ni-Al-Re ternary model single crystal alloy, Re cannot completely enter the γ' phase, and the γ' phase morphology is poor, which cannot play a good strengthening role.

[0123] Comparative Example 4: Preparation of Ni-8.5Al-4Re (wt%) ternary model single crystal alloy

[0124] The Ni-Al-Re ternary model single crystal alloy of this comparative example is Ni-8.5Al-4Re (wt%), and the preparation steps are different from those of Example 2 only in that: in this comparative example, the two-stage cooling in step S2 is changed to a one-stage cooling, and the temperature is cooled from 1330°C to room temperature by air cooling; the remaining steps are the same as those of Example 2. Specifically, the Ni-8.5Al-4Re (wt%) ternary model single crystal alloy of this comparative example is prepared according to the following steps:

[0125] S1: According to the content of Ni, Al and Re in the final alloy of 87.5wt%, 8.5wt% and 4wt% respectively, three raw materials of pure Ni, pure Al and pure Re are weighed. Pure Ni, pure Al and pure Re are mixed and melted in a vacuum induction melting furnace to make a Ni-8.5Al-4Re (wt%) master alloy. Then the master alloy is cut into small pieces, and then placed in a vacuum high gradient single crystal furnace, and a Ni-8.5Al-4Re (wt%) single crystal test bar is prepared by a spiral crystal selection process.

[0126] S2: The Ni-8.5Al-4Re (wt%) single crystal test rod was heated to 1330°C at a rate of 10°C / min, kept at this temperature for 6 hours, and then taken out and air-cooled to room temperature (25°C). The average cooling rate during the air-cooling process was 20°C / min.

[0127] S3: The Ni-8.5Al-4Re (wt%) single crystal test rod treated in step S2 is heated to 1150°C at a rate of 10°C / min, kept at this temperature for 8 hours, then taken out and air-cooled to room temperature (25°C). The average cooling rate during the air-cooling process is 20°C / min.

[0128] S4: The Ni-8.5Al-4Re (wt%) single crystal test rod after the treatment in step S3 is heated to 870°C at a rate of 10°C / min, kept at this temperature for 48 hours, then taken out and air-cooled to room temperature (25°C). The average cooling rate of the air-cooling process is 20°C / min, and a Ni-8.5Al-4Re (wt%) ternary model single crystal alloy specimen is obtained.

[0129] After testing, under the conditions of 950℃ and 100MPa, the endurance life (fracture time) of the Ni-8.5Al-4Re (wt%) ternary model single crystal alloy sample obtained in this comparative example is 164.5 hours, indicating that its high-temperature endurance performance is worse than that of the alloy sample prepared in Example 2.

[0130] Comparative Example 5: Preparation of Ni-8.5Al-4Re (wt%) ternary model single crystal alloy

[0131] The Ni-Al-Re ternary model single crystal alloy of this comparative example is Ni-8.5Al-4Re (wt%), and the preparation steps are different from those of Example 2 only in that: in this comparative example, the two-stage cooling in step S2 is changed to a one-stage cooling, and the cooling rate is 5°C / min from 1330°C to room temperature; the remaining steps are the same as those of Example 2. Specifically, the Ni-8.5Al-4Re (wt%) ternary model single crystal alloy of this comparative example is prepared according to the following steps:

[0132] S1: According to the content of Ni, Al and Re in the final alloy of 87.5wt%, 8.5wt% and 4wt% respectively, three raw materials of pure Ni, pure Al and pure Re are weighed. Pure Ni, pure Al and pure Re are mixed and melted in a vacuum induction melting furnace to make a Ni-8.5Al-4Re (wt%) master alloy. Then the master alloy is cut into small pieces, and then placed in a vacuum high gradient single crystal furnace, and a Ni-8.5Al-4Re (wt%) single crystal test bar is prepared by a spiral crystal selection process.

[0133] S2: The Ni-8.5Al-4Re (wt%) single crystal test rod was heated to 1330°C at a rate of 10°C / min, kept at this temperature for 6 hours, and cooled to room temperature (25°C) at a cooling rate of 5°C / min.

[0134] S3: The Ni-8.5Al-4Re (wt%) single crystal test rod treated in step S2 is heated to 1150°C at a rate of 10°C / min, kept at this temperature for 8 hours, then taken out and air-cooled to room temperature (25°C). The average cooling rate during the air-cooling process is 20°C / min.

[0135] S4: The Ni-8.5Al-4Re (wt%) single crystal test rod after the treatment in step S3 is heated to 870°C at a rate of 10°C / min, kept at this temperature for 48 hours, then taken out and air-cooled to room temperature (25°C). The average cooling rate of the air-cooling process is 20°C / min, and a Ni-8.5Al-4Re (wt%) ternary model single crystal alloy specimen is obtained.

[0136] After testing, under the conditions of 950℃ and 100MPa, the endurance life (fracture time) of the Ni-8.5Al-4Re (wt%) ternary model single crystal alloy sample obtained in this comparative example is 170.5 hours, indicating that its high-temperature endurance performance is worse than that of the alloy sample prepared in Example 2.

[0137] Comparative Example 6: Preparation of Ni-8.5Al-4Re (wt%) ternary model single crystal alloy

[0138] The Ni-Al-Re ternary model single crystal alloy of this comparative example is Ni-8.5Al-4Re (wt%), and the preparation steps are different from those of Example 2 only in that: in this comparative example, the temperature node for changing the cooling rate in step S2 is changed from 1150°C to 1050°C; the remaining steps are the same as those of Example 2. Specifically, the Ni-8.5Al-4Re (wt%) ternary model single crystal alloy of this comparative example is prepared according to the following steps:

[0139] S1: According to the content of Ni, Al and Re in the final alloy of 87.5wt%, 8.5wt% and 4wt% respectively, three raw materials of pure Ni, pure Al and pure Re are weighed. Pure Ni, pure Al and pure Re are mixed and melted in a vacuum induction melting furnace to make a Ni-8.5Al-4Re (wt%) master alloy. Then the master alloy is cut into small pieces, and then placed in a vacuum high gradient single crystal furnace, and a Ni-8.5Al-4Re (wt%) single crystal test bar is prepared by a spiral crystal selection process.

[0140] S2: The Ni-8.5Al-4Re (wt%) single crystal test rod was heated to 1330°C at a rate of 10°C / min, kept at that temperature for 6 hours, cooled to 1050°C at a cooling rate of 5°C / min, and then taken out and air-cooled to room temperature (25°C). The average cooling rate of the air-cooling process was 20°C / min.

[0141] S3: The Ni-8.5Al-4Re (wt%) single crystal test rod treated in step S2 is heated to 1150°C at a rate of 10°C / min, kept at this temperature for 8 hours, then taken out and air-cooled to room temperature (25°C). The average cooling rate during the air-cooling process is 20°C / min.

[0142] S4: The Ni-8.5Al-4Re (wt%) single crystal test rod after the treatment in step S3 is heated to 870°C at a rate of 10°C / min, kept at this temperature for 48 hours, then taken out and air-cooled to room temperature (25°C). The average cooling rate of the air-cooling process is 20°C / min, and a Ni-8.5Al-4Re (wt%) ternary model single crystal alloy specimen is obtained.

[0143] After testing, under the conditions of 950℃ and 100MPa, the endurance life (fracture time) of the Ni-8.5Al-4Re (wt%) ternary model single crystal alloy sample obtained in this comparative example is 141.7 hours, indicating that its high-temperature endurance performance is worse than that of the alloy sample prepared in Example 2.

[0144] Comparative Example 7: Preparation of Ni-8.5Al-4Re (wt%) ternary model single crystal alloy

[0145] The Ni-Al-Re ternary model single crystal alloy of this comparative example is Ni-8.5Al-4Re (wt%), and the preparation steps are different from those of Example 2 only in that: in this comparative example, the temperature node for changing the cooling rate in step S2 is changed from 1150°C to 1250°C; the remaining steps are the same as those of Example 2. Specifically, the Ni-8.5Al-4Re (wt%) ternary model single crystal alloy of this comparative example is prepared according to the following steps:

[0146] S1: According to the content of Ni, Al and Re in the final alloy of 87.5wt%, 8.5wt% and 4wt% respectively, three raw materials of pure Ni, pure Al and pure Re are weighed. Pure Ni, pure Al and pure Re are mixed and melted in a vacuum induction melting furnace to make a Ni-8.5Al-4Re (wt%) master alloy. Then the master alloy is cut into small pieces, and then placed in a vacuum high gradient single crystal furnace, and a Ni-8.5Al-4Re (wt%) single crystal test bar is prepared by a spiral crystal selection process.

[0147] S2: The Ni-8.5Al-4Re (wt%) single crystal test rod was heated to 1330°C at a rate of 10°C / min, kept at this temperature for 6 hours, cooled to 1250°C at a cooling rate of 5°C / min, and then air-cooled to room temperature (25°C). The average cooling rate during the air cooling process was 20°C / min.

[0148] S3: The Ni-8.5Al-4Re (wt%) single crystal test rod treated in step S2 is heated to 1150°C at a rate of 10°C / min, kept at this temperature for 8 hours, then taken out and air-cooled to room temperature (25°C). The average cooling rate during the air-cooling process is 20°C / min.

[0149] S4: The Ni-8.5Al-4Re (wt%) single crystal test rod after the treatment in step S3 is heated to 870°C at a rate of 10°C / min, kept at this temperature for 48 hours, then taken out and air-cooled to room temperature (25°C). The average cooling rate of the air-cooling process is 20°C / min, and a Ni-8.5Al-4Re (wt%) ternary model single crystal alloy specimen is obtained.

[0150] After testing, under the conditions of 950℃ and 100MPa, the endurance life (fracture time) of the Ni-8.5Al-4Re (wt%) ternary model single crystal alloy sample obtained in this comparative example is 152.8 hours, indicating that its high-temperature endurance performance is worse than that of the alloy sample prepared in Example 2.

[0151] According to the performance test results in Example 2 and Comparative Examples 4 to 7, in the cooling process of step S2, when the temperature node of the cooling rate is changed or the cooling rate of the two stages is improperly designed, the high temperature life of the alloy finally obtained will be shortened. The reason for the analysis is that the γ' phase in the Ni-Al-Re ternary model single crystal alloy begins to precipitate from about 1150°C. Slow cooling before this temperature can effectively control the nucleation of the γ' phase and form a uniform and ideal initial size and distribution, thereby providing a good organizational basis for subsequent cooling, and at the same time, it can also alleviate the stress concentration caused by the rapid precipitation of the γ' phase, avoid residual stress caused by stress concentration, and improve the service life and fatigue resistance of the alloy; the subsequent air cooling method has a faster cooling rate, which can form γ' phase particles that are not too large or uneven, which is beneficial to improve the strength and high temperature stability of the material.

[0152] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing a Ni-Al-Re ternary model single crystal alloy, characterized in that: The following steps are involved: S1: Ni, Al and Re are made into Ni-Al-Re ternary alloy, wherein the mass ratio of Al to Ni is 1:10~11; S2: The Ni-Al-Re ternary alloy is heated to 1325-1335°C, kept at this temperature for 6-8 hours, cooled to 1145-1155°C at a rate of 4-6°C / min, and then air-cooled to 20-30°C; S3: heating the Ni-Al-Re ternary alloy treated in step S2 to 1145-1155° C., keeping the temperature for 7-9 hours, and then cooling; S4: heating the Ni-Al-Re ternary alloy treated in step S3 to 865-875° C., keeping the temperature for 48-50 hours, and cooling the alloy to obtain a Ni-Al-Re ternary model single crystal alloy.

2. The preparation method according to claim 1, characterized in that: In step S1, the content of Re in the Ni-Al-Re ternary alloy is 2-4wt%.

3. The preparation method according to claim 1, characterized in that: In step S2, the average rate of air cooling is 15-20°C / min.

4. The preparation method according to claim 1, characterized in that: In steps S3 and S4, the cooling method is air cooling, the average rate is 15-20°C / min, and the terminal temperature is 20-30°C.

5. The preparation method according to claim 1, characterized in that: The specific process of step S1 includes: mixing and smelting Ni, Al and Re to obtain a master alloy; chopping the master alloy and performing spiral crystal selection to obtain a Ni-Al-Re ternary alloy.

6. The preparation method according to claim 1, characterized in that: In step S2, the rate of heating to 1325-1335°C is 5-10°C / min.

7. The preparation method according to claim 1, characterized in that: In step S3, the rate of heating to 1145-1155°C is 5-10°C / min.

8. The preparation method according to claim 1, characterized in that: In step S4, the rate of heating to 865-875°C is 5-10°C / min.

9. A Ni-Al-Re ternary model single crystal alloy prepared by the preparation method according to any one of claims 1 to 8.

Images