Ni3Al-based single crystal alloy and preparation method and application thereof

Abstract

The invention belongs to the technical field of single crystal alloys, and particularly relates to a Ni3Al-based single crystal alloy and a preparation method and application thereof. The Ni3Al-based single crystal alloy provided by the invention comprises the following element components in percentage by mass: 7.0 to 8.2 wt.% of Al, 2.4 to 3.8 wt.% of Ta, 7.9 to 9.8 wt.% of Mo, 1.5 to 3.6 wt.% of Re, 0.9 to 1.8 wt.% of Cr and the balance of Ni, the Ni3Al-based single crystal alloy comprises a gamma '-Ni3Al phase and a gamma-Ni phase. According to the invention, the contents of Al and Ta elements are increased, so that a gamma '-Ni3Al phase and a gamma-Ni phase are formed in the alloy; mo is used for replacing part of Re, the temperature bearing capacity of the single crystal alloy is improved through high-mismatch-degree alloying design, meanwhile, the cost of the alloy is remarkably reduced, and the endurance life is longer than 150 h under the conditions of 1200 DEG C and 80 MPa.

Description

Technical Field

[0001] The invention belongs to the technical field of single crystal alloys, and in particular relates to a Ni3Al-based single crystal alloy and a preparation method and application thereof. Background Art

[0002] With the continuous increase in the inlet temperature of the turbine of large and medium thrust aircraft engines, combined with the blade super air cooling structure design and the thermal insulation effect of the thermal barrier coating, the temperature bearing capacity of the future advanced high-pressure turbine guide blade materials must reach 1200℃. At present, the service temperature of the third-generation single crystal high-temperature alloy used for aircraft engine turbine blade materials internationally is 1100℃, and the target service temperature of the fourth and fifth-generation single crystal high-temperature alloys under research is 1120~1150℃. There are no reports on ultra-high temperature single crystal alloy materials and alloy design concepts that can reach 1200℃ and above for a long time. Looking at the development history of nickel-based single crystal high-temperature alloys, from the service temperature of 1070℃ of the second-generation single crystal high-temperature alloy to the target service temperature of 1150℃ of the fifth-generation single crystal high-temperature alloy, the content of precious metal Re in the alloy has increased from 3% to 6%, and 3%Ru~6%Ru is added to stabilize the instability of the alloy structure caused by the introduction of elements such as Re. The cost remains high, and the fifth-generation single crystal high-temperature alloy has been called "unaffordable materials." High-temperature structural materials for high-pressure turbine guide blades that can withstand temperatures of 1200°C are facing a situation where there is "no material available". Summary of the invention

[0003] In view of this, the present invention provides a Ni3Al-based single crystal alloy and a preparation method and application thereof. The Ni3Al-based single crystal alloy provided by the present invention has a high temperature bearing capacity, and its endurance life is greater than 150h under the conditions of 1200°C and 80MPa, which can meet the requirements for preparing high-pressure turbine blades of aircraft engines.

[0004] In order to solve the above technical problems, the present invention provides a Ni3Al-based single crystal alloy, comprising the following element components in percentage by mass:

[0005]

[0006] The Ni3Al-based single crystal alloy includes a γ'-Ni3Al phase and a γ-Ni phase.

[0007] Preferably, the volume fraction of the γ'-Ni3Al phase is 76-82 vol.%, and the volume fraction of the γ-Ni phase is 8-24 vol.%.

[0008] Preferably, the single crystal orientation of the Ni3Al-based single crystal alloy includes

[001] orientation,

[011] orientation or

[111] orientation.

[0009] The present invention also provides a method for preparing the Ni3Al-based single crystal alloy described in the above technical solution, comprising the following steps:

[0010] Mixing the materials according to the element ratio and smelting them to prepare a master alloy;

[0011] Remelting the master alloy and then performing directionally solidification according to a seed crystal method to obtain single crystal alloys with different orientations;

[0012] The single crystal alloys with different orientations are subjected to solution treatment and aging treatment in sequence to obtain the Ni3Al-based single crystal alloys.

[0013] Preferably, the temperature of the solution treatment is 1300-1330° C., and the holding time is 20-30 hours.

[0014] Preferably, the aging treatment includes primary aging treatment and secondary aging treatment performed sequentially.

[0015] Preferably, the temperature of the primary aging treatment is 1000-1100°C, and the holding time is 2-4h;

[0016] The temperature of the secondary aging treatment is 850-900° C., and the insulation time is 30-34 hours.

[0017] Preferably, the method for preparing the single crystal rod wax mold used in the directional solidification process according to the seed crystal method comprises the following steps: placing a seed crystal in the seed crystal wax mold for pressing to obtain the single crystal rod wax mold;

[0018] The orientation of the seed crystal includes

[001] orientation,

[011] orientation or

[111] orientation;

[0019] The pressing temperature is 45 to 70° C., the pressing pressure is 6 to 15 MPa, and the holding time of the pressing is 10 to 30 seconds.

[0020] Preferably, the crystal pulling rate of the directional solidification is 1 to 5 mm / s.

[0021] The present invention also provides the use of the Ni3Al-based single crystal alloy described in the above technical solution or the Ni3Al-based single crystal alloy prepared by the preparation method described in the above technical solution in the preparation of aircraft engine turbines.

[0022] The present invention provides a Ni3Al-based single crystal alloy, comprising the following element components in percentage by mass: 7.0-8.2wt.% Al, 2.4-3.8wt.% Ta, 7.9-9.8wt.% Mo, 1.5-3.6wt.% Re, 0.9-1.8wt.% Cr and balance Ni; the Ni3Al-based single crystal alloy comprises γ'-Ni3Al phase and γ-Ni phase. The present invention forms γ'-Ni3Al phase and γ-Ni phase in the alloy by increasing the content of Al and Ta elements; the present invention replaces part of Re with Mo, and improves the temperature bearing capacity of the single crystal alloy under the synergistic effect of various elements through high mismatch alloying design, while significantly reducing the cost of the alloy; the cost of the Ni3Al-based single crystal alloy provided by the present invention is only 56.27% and 59.46% of the international mainstream third-generation single crystal alloys CMSX-10 and N6, respectively, which has a significant cost advantage. The Ni3Al-based single crystal alloy provided by the present invention has good temperature bearing capacity and a long-lasting life of more than 150 hours under the conditions of 1200° C. and 80 MPa. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the dislocation configuration diagram of the

[001] oriented Ni3Al-based single crystal alloy prepared in Example 1;

[0024] Figure 2 The microstructure of the

[001] oriented Ni3Al-based single crystal alloy prepared in Example 1;

[0025] Figure 3 The microstructure of the

[011] oriented Ni3Al-based single crystal alloy prepared in Example 2;

[0026] Figure 4 The microstructure of the

[111] oriented Ni3Al-based single crystal alloy prepared in Example 3;

[0027] Figure 5 It is a columnar comparison chart of the fracture time of the single crystal alloys of Examples 1 to 3 and Comparative Examples 1 to 3 placed at a temperature of 1200° C. and a pressure of 80 MPa. DETAILED DESCRIPTION

[0028] The present invention provides a Ni3Al-based single crystal alloy, comprising the following element components in percentage by mass:

[0029]

[0030] The Ni3Al-based single crystal alloy includes a γ'-Ni3Al phase and a γ-Ni phase.

[0031] In terms of mass percentage, the Ni3Al-based single crystal alloy provided by the present invention includes 7.0-8.2wt.% Al, which may be specifically 7.0wt.%, 7.3wt.%, 7.5wt.%, 7.8wt.%, 8.0wt.% or 8.2wt.%. In the present invention, the Al element is a forming element of the γ'-Ni3Al phase and a key element for increasing the "enrichment" of the γ'-Ni3Al phase. The increase in the Al content helps to increase the volume fraction of the γ'-Ni3Al phase and also improves the high-temperature oxidation resistance of the Ni3Al-based single crystal alloy.

[0032] In terms of mass percentage, the Ni3Al-based single crystal alloy provided by the present invention includes 2.4-3.8wt.% Ta, which may be specifically 2.4wt.%, 2.6wt.%, 2.8wt.%, 3.0wt.%, 3.2wt.%, 3.5wt.% or 3.8wt.%. In the present invention, the Ta element is also a forming element of the γ'-Ni3Al phase and a key element for the "strengthening" of the γ'-Ni3Al phase. The increase in the Ta content helps to improve the ultra-high temperature thermal stability of the γ'-Ni3Al phase.

[0033] In terms of mass percentage, the Ni3Al-based single crystal alloy provided by the present invention includes 7.9-9.8wt.% Mo, which can be specifically 7.9wt.%, 8.0wt.%, 8.5wt.%, 8.8wt.%, 9.0wt.%, 9.3wt.%, 9.5wt.% or 9.8wt.%. In the present invention, the Mo element is a strengthening element of the γ'-Ni phase and is mainly distributed in the γ'-Ni phase. The alloying design principle of "replacing part of Re with Mo" adopted in the present invention is the key to the low cost of the Ni3Al-based single crystal alloy. At the same time, the atomic radius of the Mo element is large, which produces lattice distortion in the γ'-Ni phase, increases the mismatch of the Ni3Al-based single crystal alloy, and promotes the Ni3Al-based single crystal alloy to form an N-type raft during ultra-high temperature deformation. The distance between the rafts is small, and a dense interface dislocation network is generated, which significantly limits and hinders the dislocation movement, and improves the high temperature endurance performance of the Ni3Al-based single crystal alloy. Figure 1 Dislocation configuration diagram of the

[001] oriented Ni3Al-based single crystal alloy prepared in Example 1.

[0034] In terms of mass percentage, the Ni3Al-based single crystal alloy provided by the present invention includes 1.5-3.6%wt.%Re, which can be specifically 1.5wt.%, 1.8wt.%, 2.0wt.%, 2.3wt.%, 2.5wt.%, 2.8wt.%, 3.0wt.%, 3.3wt.% or 3.6wt.%. In the present invention, the Re element is a strengthening element of the γ'-Ni phase, and is mainly distributed in the γ'-Ni phase. When the Re element is enriched at the γ'-Ni3Al phase / γ'-Ni phase interface, a "Re element cluster effect" is generated, which can significantly hinder the movement of dislocations and improve the high-temperature endurance performance. However, too high a content of the Re element will cause the organization stability to become unstable, produce a TCP phase, and reduce the high-temperature endurance performance of the material. Therefore, the Re content needs to be controlled within a suitable range.

[0035] The present invention introduces the γ-Ni phase to coordinate the organization regulation, increases the critical shear stress of APB shear, improves the ability of Ni3Al-based single crystal alloy to hinder dislocation movement under different orientations, and enables Ni3Al-based single crystal alloy to have a wide orientation advantage under ultra-high temperature conditions.

[0036] In terms of mass percentage, the Ni3Al-based single crystal alloy provided by the present invention includes 0.9-1.8wt.% Cr, which may be specifically 0.9wt.%, 1.0wt.%, 1.3wt.%, 1.5wt.% or 1.8wt.%. In the present invention, the Cr element mainly improves the oxidation resistance and corrosion resistance of the Ni3Al-based single crystal alloy, and does not contribute much to the strength of the Ni3Al-based single crystal alloy. At the same time, excessive Cr content, on the one hand, sacrifices the high-temperature durability of the Ni3Al-based single crystal alloy, and on the other hand, produces a large amount of TCP phase during service, reducing the organizational stability of the Ni3Al-based single crystal alloy. Therefore, the Cr content also needs to be controlled within a suitable range.

[0037] The Ni3Al-based single crystal alloy provided by the present invention includes the balance of Ni in terms of mass percentage. In the present invention, the Ni element is a forming element of the γ'-Ni phase and the γ'-Ni3Al phase.

[0038] In the present invention, the Ni3Al-based single crystal alloy includes a γ'-Ni3Al phase and a γ-Ni phase, the volume fraction of the γ'-Ni3Al phase can be 76 to 82 vol.%, and the volume fraction of the γ-Ni phase can be 8 to 24 vol.%; the single crystal orientation of the Ni3Al-based single crystal alloy includes a

[001] orientation, a

[011] orientation or a

[111] orientation.

[0039] The present invention adopts the organizational design idea of ​​the synergistic effect of the γ'-Ni3Al phase and the γ-Ni phase, and adopts the alloying design idea of ​​high Al-rich γ'-Ni3Al phase volume fraction and high Ta-strong γ'-Ni3Al phase to improve the ultra-high temperature thermal stability of the γ'-Ni3Al phase. At the same time, combined with the high mismatch alloying synergistic control design using Mo instead of Re, the mismatch of the γ'-Ni3Al and γ-Ni phases is fully controlled, the density of the interface dislocation network is increased, and the ultra-high temperature organizational stability is enhanced, while also significantly improving the temperature bearing capacity of the Ni3Al-based single crystal alloy.

[0040] The γ'-Ni3Al phase is the most effective strengthening phase at high temperatures, significantly hindering the movement of dislocations. Because the γ'-Ni3Al phase will undergo significant dissolution under ultra-high temperature conditions of 1200°C, the volume fraction of the γ'-Ni3Al phase in mainstream single crystal alloys at home and abroad has dropped significantly, and the ultra-high temperature bearing capacity has dropped significantly. The Ni3Al-based single crystal alloy provided by the present invention adopts a two-phase structure, with the γ'-Ni3Al phase as the main body and the γ-Ni phase as a synergist. The design of the rich γ'-Ni3Al phase volume fraction and the strong γ'-Ni3Al phase helps to improve the thermal stability of the γ'-Ni3Al phase under ultra-high temperature conditions and increase the structural stability of the Ni3Al-based single crystal alloy under ultra-high temperature conditions. Under ultra-high temperature conditions, dislocation movement is mainly based on the APB shear γ'-Ni3Al phase. The critical shear stress required for APB shear is shown in the following formula:

[0041]

[0042] Where d is the size of the γ'-Ni3Al phase. It is not difficult to see that the critical shear stress required for APB shearing is inversely proportional to the size of the γ'-Ni3Al phase. The pure single-phase γ'-Ni3Al phase is equivalent to a large size of the γ'-Ni3Al phase. At this time, the critical shear stress required for APB activation is very small, and it cannot effectively hinder the dislocation movement. Therefore, a small amount of γ-Ni phase is introduced to improve the precipitation size and morphology of the γ'-Ni3Al phase, and increase the critical shear stress required for APB activation. At the same time, the introduction of the γ-Ni phase can increase the mismatch between the two phases, form an interface dislocation network at high temperature, enhance the mismatch strengthening effect, significantly hinder dislocations, and improve the ultra-high temperature strength of Ni3Al-based single crystal alloys.

[0043] The present invention also provides a method for preparing the Ni3Al-based single crystal alloy described in the above technical solution, comprising the following steps:

[0044] Mixing the materials according to the element ratio and smelting them to prepare a master alloy;

[0045] Remelting the master alloy and then performing directionally solidification according to a seed crystal method to obtain single crystal alloys with different orientations;

[0046] The single crystal alloys with different orientations are subjected to solution treatment and aging treatment in sequence to obtain the Ni3Al-based single crystal alloys.

[0047] The present invention mixes materials according to the element ratio and smelts them to prepare a master alloy. As a specific embodiment of the present invention, the smelting can be vacuum induction smelting. The present invention has no special limitation on the vacuum induction smelting, and the smelting can be carried out in a conventional manner in the art.

[0048] After obtaining the master alloy, the present invention remelts the master alloy and then performs directional solidification according to the seed crystal method to obtain single crystal alloys with different orientations. As a specific embodiment of the present invention, the method for preparing the single crystal rod wax mold used in the directional solidification process according to the seed crystal method may include the following steps: placing a seed crystal in the seed crystal wax mold for pressing to obtain the single crystal rod wax mold; the orientation of the seed crystal may include

[001] orientation,

[011] orientation or

[111] orientation; the pressing temperature may be 45 to 70°C, specifically 45°C, 50°C, 55°C, 60°C, 65°C or 70°C; the pressing pressure may be 6 to 15MPa, specifically 6MPa, 8MPa, 10MPa, 12MPa or 15MPa; the holding time of the pressing may be 10 to 30s, or 15 to 25s, specifically 10s, 15s, 20s, 25s or 30s. As a specific embodiment of the present invention, the pressing may be performed in a high-pressure injection molding machine.

[0049] As a specific embodiment of the present invention, the crystal pulling rate of the directional solidification can be 1-5 mm / s, or 2-4 mm / s, and can be specifically 1 mm / s, 1.5 mm / s, 2 mm / s, 2.5 mm / s, 3 mm / s, 3.5 mm / s, 4 mm / s, 4.5 mm / s or 5 mm / s. The present invention adopts the seed crystal method for crystal directional solidification and limits the crystal pulling rate within the above range to prepare a Ni3Al-based single crystal alloy with an orientation of

[001] ,

[011] or

[111] .

[0050] After obtaining the single crystal alloys with different orientations, the present invention sequentially performs solution treatment and aging treatment on the single crystal alloys with different orientations to obtain the Ni3Al-based single crystal alloy. As a specific embodiment of the present invention, the temperature of the solution treatment can be 1300-1330°C, specifically 1300°C, 1310°C, 1320°C or 1330°C; the holding time of the solution treatment can be 20-30h, specifically 20h, 22h, 25h, 28h or 30h. The present invention can eliminate the cast structure and element segregation of the alloy through solution treatment, dissolve the coarse primary γ' phase and γ / γ' eutectic phase, so as to increase the initial melting temperature of the alloy, so that the solution can be carried out at a higher temperature to achieve element homogenization. In order to fully eliminate dendrite segregation, the temperature of the solution treatment is usually greater than the complete dissolution temperature of the γ' phase and lower than the initial melting temperature of the alloy.

[0051] As a specific embodiment of the present invention, the solution treatment may further include: cooling the product after the solution treatment to room temperature; the cooling method may be air cooling, and the room temperature may be 20-30°C.

[0052] As a specific embodiment of the present invention, the aging treatment includes a primary aging treatment and a secondary aging treatment performed in sequence; the temperature of the primary aging treatment can be 1000-1100°C, and can be specifically 1000°C, 1010°C, 1020°C, 1030°C, 1040°C, 1050°C, 1060°C, 1070°C, 1080°C, 1090°C or 1100°C; the insulation time of the primary aging treatment can be 2-4h, and can be specifically 2h, 2.5h, 3h, 3.5h or 4h. As a specific embodiment of the present invention, the primary aging treatment can also include: cooling the product after the primary aging treatment to room temperature; the cooling method can be air cooling, and the temperature of the room temperature can be 20-30°C.

[0053] As a specific embodiment of the present invention, the temperature of the secondary aging treatment can be 850-900°C, and can be specifically 850°C, 860°C, 870°C, 880°C, 890°C or 900°C; the holding time of the secondary aging treatment can be 30-34h, and can be specifically 30h, 31h, 32h, 33h or 34h. As a specific embodiment of the present invention, the secondary aging treatment can also include: cooling the product after the secondary aging treatment to room temperature; the cooling method can be air cooling, and the temperature of the room temperature can be 20-30°C.

[0054] The present invention can adjust the morphology, size and cubicity of the γ' phase through primary aging treatment; and can adjust the cubicity of the γ' phase through secondary aging treatment.

[0055] The present invention also provides the use of the Ni3Al-based single crystal alloy described in the above technical solution or the Ni3Al-based single crystal alloy prepared by the preparation method described in the above technical solution in the preparation of aircraft engine turbines. The Ni3Al-based single crystal alloy provided by the present invention has the advantages of low cost, high temperature resistance and wide orientation, and is suitable for high-pressure turbine guide blades and high-pressure turbine outer rings of advanced aircraft engines.

[0056] In order to further illustrate the present invention, the technical solutions provided by the present invention are described in detail below in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0057] Example 1

[0058] Master alloy smelting: weigh the raw materials used for the alloy according to the element ratio, and smelt them in a vacuum induction melting furnace to prepare the master alloy;

[0059] Single crystal rod wax mold pressing: Place the

[001] oriented seed crystal into the seed crystal wax mold, and use a high-pressure injection molding machine to press the seed crystal wax mold. The pressing pressure is 10MPa, the holding time is 20s, and the pressing temperature is 50°C.

[0060] Directional solidification was carried out according to the seed crystal method: the mother alloy was remelted in a single crystal furnace and then cast to obtain a

[001] oriented single crystal alloy rod, wherein the crystal pulling rate was 2.0 mm / s;

[0061] Heat treatment: The

[001] oriented single crystal alloy rod is kept at 1320°C for 20 hours for solution treatment and then air-cooled to 25°C; the product after solution treatment is kept at 1050°C for 3 hours for primary aging treatment and then air-cooled to 25°C; the product after primary aging treatment is kept at 880°C for 33 hours for secondary aging treatment and then air-cooled to 25°C to obtain a

[001] oriented Ni3Al-based single crystal alloy, the element content of the Ni3Al-based single crystal alloy is 7.4wt.%Al, 4wt.%Ta, 9.5wt.%Mo, 3%wt.%Re, 1.5wt.%Cr and the balance Ni.

[0062] Example 2

[0063] A Ni3Al-based single crystal alloy is prepared according to the method of Example 1, except that the

[001] -oriented seed crystal is replaced by a

[011] -oriented seed crystal to obtain a

[011] -oriented Ni3Al-based single crystal alloy. The element content of the

[011] -oriented Ni3Al-based single crystal alloy is 7.4wt.%Al, 4wt.%Ta, 9.5wt.%Mo, 3wt.%Re, 1.5wt.%Cr and the remainder Ni.

[0064] Example 3

[0065] A Ni3Al-based single crystal alloy is prepared according to the method of Example 1, except that the

[001] -oriented seed crystal is replaced by a

[111] -oriented seed crystal to obtain a

[111] -oriented Ni3Al-based single crystal alloy. The element content of the

[111] -oriented Ni3Al-based single crystal alloy is 7.4wt.%Al, 4wt.%Ta, 9.5wt.%Mo, 3wt.%Re, 1.5wt.%Cr and the remainder Ni.

[0066] Comparative Example 1

[0067] Taking AM1 nickel-based single crystal alloy as a comparative example, the composition of AM1 nickel-based single crystal alloy is: Cr: 7.8wt.%, Co: 6.5wt.%, Mo: 2wt.%, W: 5.7wt.%, Al: 5.2wt%, Ti: 1.1wt%, Ta: 7.9wt.%, Ni: balance.

[0068] Comparative Example 2

[0069] Taking CMSX-4 single crystal alloy as a comparative example, the composition of CMSX-4 single crystal alloy is: Cr: 6.5wt.%, Co: 9wt.%, Mo: 0.6wt.%, W: 6wt.%, Al: 5.6wt.%, Ti: 1wt.%, Ta: 6.5wt.%, Re: 3wt.%, Ni: balance.

[0070] Comparative Example 3

[0071] Taking MC-NG single crystal alloy as a comparative example, the composition of MC-NG single crystal alloy is: Cr: 4wt.%, Co: 0.1~0.2wt.%, Mo: 1wt.%, W: 5wt.%, Al: 6wt.%, Ti: 0.5wt.%, Ta: 5wt.%, Re: 4wt%, Ni: balance.

[0072] The Ni3Al-based single crystal alloys prepared in Examples 1 to 3 were examined using a metallographic microscope to obtain microstructure diagrams, as shown in FIG. Figures 2 to 4 ,in Figure 2 The microstructure of the

[001] oriented Ni3Al-based single crystal alloy is shown in Figure 2. Figure 3 is the microstructure of the

[011] oriented Ni3Al-based single crystal alloy. Figure 4 The microstructure of the

[111] oriented Ni3Al-based single crystal alloy. Figures 2 to 4 It can be seen that after heat treatment, the two-phase structures of Ni3Al-based single crystal alloys with different orientations have been completely dissolved, without initial melting or incomplete solid solution. Figure 2The microstructure of the

[001] oriented Ni3Al-based single crystal alloy is cubic, the size of the γ'-Ni3Al phase is about 209nm, and the volume fraction of the γ'-Ni3Al phase is 78%; the size of the γ-Ni phase is about 38nm, and the volume fraction of the γ-Ni phase is 22%. Figure 3 The γ'-Ni3Al phase morphology in the microstructure of the

[011] oriented Ni3Al-based single crystal alloy is rectangular. Figure 4 The γ'-Ni3Al phase in the microstructure of the

[111] oriented Ni3Al-based single crystal alloy presents a triangular shape. The size of the γ'-Ni3Al phase in the non-preferred orientation (

[011] orientation and

[111] orientation) is irregular and difficult to count.

[0073] The single crystal alloys of Examples 1 to 3 and Comparative Examples 1 to 3 were placed at a temperature of 1200° C. and a pressure of 80 MPa for endurance performance testing (recording the time when the sample broke). The results are listed in Table 1.

[0074] Table 1 Fracture time of single crystal alloys of Examples 1 to 3 and Comparative Examples 1 to 3 under high temperature and high pressure

[0075] Example Breaking time (h) Example 1 159 Example 2 150.8 Example 3 190 Comparative Example 1 10 Comparative Example 2 13 Comparative Example 3 15

[0076] According to Table 1, a columnar comparison chart of the fracture time of the single crystal alloys of Examples 1 to 3 and Comparative Examples 1 to 3 placed at a temperature of 1200° C. and a pressure of 80 MPa is drawn, as shown in FIG. Figure 5 Combining Table 1 and Figure 5 It can be seen that the Ni3Al-based single crystal alloy provided by the present invention has a long lasting fracture time under conditions of high temperature and high pressure, indicating that it has good high temperature and high pressure resistance.

[0077] The Ni3Al-based single crystal alloy provided by the present invention has significantly improved organizational stability at a service temperature of 1200°C, especially the γ′ phase has excellent thermal stability. The stability of the microstructure of the single crystal alloy at a temperature above 1200°C is mainly due to the strong dissolution of the γ′ phase, which leads to a rapid decrease in the content of the γ′-Ni3Al phase. For example, after thermal equilibrium at 1200°C, the γ′-Ni3Al phase content of the Rene N5 alloy is only 45%, which is about 25% less than that at 1150°C; similarly, after thermal equilibrium at 1200°C, the γ′-Ni3Al phase content of the MC-NG alloy drops rapidly from 60% (after thermal equilibrium at 1100°C) to less than 50%. The Ni3Al-based single crystal alloy provided by the present invention adopts the design concept of rich γ′ phase volume fraction and strong γ′ phase, and successfully regulates and prepares a single crystal intermetallic compound with excellent organizational stability at a service temperature of 1200°C. The service results show that the volume fraction of the alloy at 1200°C is as high as 65vol.% or more.

[0078] The Ni3Al-based single crystal alloy provided by the present invention has ultra-high temperature endurance performance, especially 1200℃ / 80MPa endurance life. For example, the endurance life of the fourth-generation single crystal alloy MC-NG at 1150℃ / 100MPa is greater than 150h, while it is sharply reduced to 15h at 1200℃ / 100MPa. The

[001] -oriented Ni3Al-based single crystal alloy provided by the present invention has an endurance life of 159h at 1200℃ / 80MPa, which is 10 times that of the fourth-generation single crystal.

[0079] The Ni3Al-based single crystal alloy provided by the present invention has a wide range of orientation advantages under ultra-high temperature conditions, that is, it has excellent high-temperature endurance performance in all orientations. The Ni3Al-based single crystal alloy developed by the present invention has significant advantages in the

[001] orientation. Under the conditions of 1200°C / 80MPa, the endurance life of the

[011] and

[111] oriented Ni3Al-based single crystal alloys is as high as 150.8h and 190h.

[0080] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A Ni3Al-based single crystal alloy, characterized in that: Includes the following elemental components in mass percentage: The Ni3Al-based single crystal alloy includes a γ'-Ni3Al phase and a γ-Ni phase.

2. The Ni3Al-based single crystal alloy according to claim 1, characterized in that: The volume fraction of the γ′-Ni3Al phase is 76 to 82 vol.%, and the volume fraction of the γ-Ni phase is 8 to 24 vol.%.

3. The Ni3Al-based single crystal alloy according to claim 1 or 2, characterized in that: The single crystal orientation of the Ni3Al-based single crystal alloy includes [001] orientation, [011] orientation or [111] orientation.

4. The method for preparing the Ni3Al-based single crystal alloy according to any one of claims 1 to 3, characterized in that: The following steps are involved: Mixing the materials according to the element ratio and smelting them to prepare a master alloy; Remelting the master alloy and then performing directionally solidification according to a seed crystal method to obtain single crystal alloys with different orientations; The single crystal alloys with different orientations are subjected to solution treatment and aging treatment in sequence to obtain the Ni3Al-based single crystal alloys.

5. The preparation method according to claim 4, characterized in that: The temperature of the solution treatment is 1300-1330° C., and the holding time is 20-30 hours.

6. The preparation method according to claim 4, characterized in that: The aging treatment includes primary aging treatment and secondary aging treatment performed sequentially.

7. The preparation method according to claim 6, characterized in that: The temperature of the primary aging treatment is 1000-1100°C, and the holding time is 2-4h; The temperature of the secondary aging treatment is 850-900° C., and the insulation time is 30-34 hours.

8. The preparation method according to claim 4, characterized in that: The method for preparing a single crystal rod wax mold used in a directional solidification process according to a seed crystal method comprises the following steps: placing a seed crystal in the seed crystal wax mold for pressing to obtain the single crystal rod wax mold; The orientation of the seed crystal includes [001] orientation, [011] orientation or [111] orientation; The pressing temperature is 45 to 70° C., the pressing pressure is 6 to 15 MPa, and the holding time of the pressing is 10 to 30 seconds.

9. The preparation method according to claim 4 or 8, characterized in that: The crystal pulling rate of the directional solidification is 1 to 5 mm / s.

10. Use of the Ni3Al-based single crystal alloy according to any one of claims 1 to 3 or the Ni3Al-based single crystal alloy prepared by the preparation method according to any one of claims 4 to 9 in the preparation of aircraft engine turbines.

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