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

Abstract

The application 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 application comprises the following mass percentage of element components: 7.0-8.2 wt.% Al, 2.4-3.8 wt.% Ta, 7.9-9.8 wt.% Mo, 1.5-3.6 wt.% Re, 0.9-1.8 wt.% Cr and the balance of Ni; the Ni3Al-based single crystal alloy comprises a γ'-Ni3Al phase and a γ-Ni phase. The application increases the contents of Al and Ta to form the γ'-Ni3Al phase and the γ-Ni phase in the alloy; Mo is used to replace part of Re, the temperature bearing capacity of the single crystal alloy is improved through high-mismatching alloying design, and the cost of the alloy is significantly reduced, and the stress-rupture life is greater than 150 h under the condition of 1200 DEG C and 80 MPa.

Description

TECHNICAL FIELD

[0001] The application 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. BACKGROUND

[0002] With the continuous increase of the turbine inlet temperature of medium and large thrust aero-engine, combined with the heat insulation effect of the blade super-air cooling structure design and thermal barrier coating, the temperature resistance capacity of the future advanced high-pressure turbine guide vane material needs to reach 1200 DEG C. At present, the third generation single crystal superalloy used for aero-engine turbine blade material in the international makes the service temperature 1100 DEG C, the fourth generation and the fifth generation single crystal superalloy under research have the target service temperature of 1120-1150 DEG C, and the long-time service temperature can reach 1200 DEG C and above. The ultra-high temperature single crystal superalloy material and alloy design concept have not been reported. Looking back at the development history of the nickel-based single crystal superalloy, from the second generation single crystal superalloy with the service temperature of 1070 DEG C to the fifth generation single crystal superalloy with the target service temperature of 1150 DEG C, the content of the noble metal Re in the alloy is increased from 3% to 6%, and 3% Ru-6% Ru is added to stabilize the alloy organization instability caused by the introduction of Re and other elements. The cost is high, and the fifth generation single crystal superalloy has been called 'unaffordable material'. The high-pressure turbine guide vane high-temperature structural material with the temperature resistance of 1200 DEG C is faced with the situation of 'no material available'. SUMMARY

[0003] Therefore, the application provides a Ni3Al-based single crystal alloy and a preparation method and application thereof. The Ni3Al-based single crystal alloy has high temperature resistance, and the long-time life is greater than 150 h under the condition of 1200 DEG C and 80 MPa, which can meet the requirements of preparing the high-pressure turbine blade of an aero-engine.

[0004] In order to solve the above technical problems, the application provides a Ni3Al-based single crystal alloy, which comprises the following mass percentage of element components:

[0005]

[0006] The Ni3Al-based single crystal alloy comprises 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 comprises

[001] orientation,

[011] orientation or

[111] orientation.

[0009] The application further provides a preparation method of the Ni3Al-based single crystal alloy.

[0010] The material is mixed according to the element ratio and is smelted to prepare a master alloy.

[0011] The master alloy is remelted and directionally solidified according to a seed crystal method to obtain different orientation single crystal alloys.

[0012] The different orientation single crystal alloys are sequentially subjected to solid solution treatment and aging treatment to obtain the Ni3Al-based single crystal alloy.

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

[0014] Preferably, the aging treatment comprises sequentially performing primary aging treatment and secondary aging treatment.

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

[0016] The temperature of the secondary aging treatment is 850-900 DEG C, and the holding time is 30-34 h.

[0017] Preferably, the preparation method of the single crystal rod wax mold in the process of the directionally solidifying according to the seed crystal method comprises the following steps: the seed crystal is pressed in a seed crystal wax mold to obtain the single crystal rod wax mold.

[0018] The orientation of the seed crystal comprises

[001] orientation,

[011] orientation or

[111] orientation.

[0019] The temperature of the pressing is 45-70 DEG C, the pressure of the pressing is 6-15 MPa, and the holding time of the pressing is 10-30 s.

[0020] Preferably, the pulling rate of the directionally solidifying is 1-5 mm / s.

[0021] The application further provides application of the Ni3Al-based single crystal alloy or the Ni3Al-based single crystal alloy prepared by the preparation method in the preparation of an aero-engine turbine.

[0022] The application provides a Ni3Al-based single crystal alloy, which comprises the following mass percentage of element components: 7.0-8.2 wt. % Al, 2.4-3.8 wt. % Ta, 7.9-9.8 wt. % Mo, 1.5-3.6 wt. % Re, 0.9-1.8 wt. % Cr and the balance of Ni; the Ni3Al-based single crystal alloy comprises a γ'-Ni3Al phase and a γ-Ni phase. The application forms the γ'-Ni3Al phase and the γ-Ni phase in the alloy by increasing the contents of Al and Ta elements; the application replaces part of Re with Mo, and improves the temperature bearing capacity of the single crystal alloy under the synergistic effect of various elements, while significantly reducing the cost of the alloy; the cost of the Ni3Al-based single crystal alloy provided by the application is only 56.27 % and 59.46 % of the costs of international mainstream third-generation single crystal alloys CMSX-10 and N6, and the Ni3Al-based single crystal alloy has a significant cost advantage. The Ni3Al-based single crystal alloy provided by the application has good temperature bearing capacity, and the creep life is greater than 150 h under the condition of 1200 DEG C and 80 MPa. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 A dislocation configuration diagram of the

[001] -oriented Ni3Al-based single crystal alloy prepared in Example 1 is shown in the following figure:

[0024] Figure 2 A microstructure diagram of the

[001] -oriented Ni3Al-based single crystal alloy prepared in Example 1 is shown in the following figure:

[0025] Figure 3 A microstructure diagram of the

[011] -oriented Ni3Al-based single crystal alloy prepared in Example 2 is shown in the following figure:

[0026] Figure 4 A microstructure diagram of the

[111] -oriented Ni3Al-based single crystal alloy prepared in Example 3 is shown in the following figure:

[0027] Figure 5 A columnar comparison diagram of the fracture time of the single crystal alloys in Examples 1-3 and Comparative Examples 1-3 under the condition of 1200 DEG C and 80 MPa is shown in the following figure. DETAILED DESCRIPTION

[0028] The application provides a Ni3Al-based single crystal alloy, which comprises the following mass percentage of element components:

[0029]

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

[0031] The Ni3Al-based single crystal alloy provided by the application contains 7.0-8.2 wt.% Al, and can be specifically 7.0 wt.%, 7.3 wt.%, 7.5 wt.%, 7.8 wt.%, 8.0 wt.% or 8.2 wt.%. In the application, the Al element is a forming element of the γ'-Ni3Al phase and is a key element for improving the "richness" of the γ'-Ni3Al phase. The increase of the Al content helps to improve the volume fraction of the γ'-Ni3Al phase and also improves the high-temperature oxidation resistance of the Ni3Al-based single crystal alloy.

[0032] The Ni3Al-based single crystal alloy provided by the application contains 2.4-3.8 wt.% Ta, and can be specifically 2.4 wt.%, 2.6 wt.%, 2.8 wt.%, 3.0 wt.%, 3.2 wt.%, 3.5 wt.% or 3.8 wt.%. In the application, the Ta element is also a forming element of the γ'-Ni3Al phase and is a key element for improving the "strength" of the γ'-Ni3Al phase. The increase of the Ta content helps to improve the ultrahigh-temperature thermal stability of the γ'-Ni3Al phase.

[0033] The Ni3Al-based single crystal alloy provided by the application contains 7.9-9.8 wt.% Mo, and can be specifically 7.9 wt.%, 8.0 wt.%, 8.5 wt.%, 8.8 wt.%, 9.0 wt.%, 9.3 wt.%, 9.5 wt.% or 9.8 wt.%. In the application, the Mo element is a strengthening element of the γ'-Ni phase and is mainly distributed in the γ'-Ni phase. The alloying design criterion of "replacing part of Re with Mo" in the application is a key to the low cost of the Ni3Al-based single crystal alloy. At the same time, the Mo element has a large atomic radius and produces lattice distortion in the γ'-Ni phase, increases the mismatch degree of the Ni3Al-based single crystal alloy, and promotes the formation of N-type raft in the Ni3Al-based single crystal alloy during ultrahigh-temperature deformation. The distance between the rafts is small, and a dense interface dislocation network is generated, which significantly limits and hinders the movement of dislocations and improves the high-temperature stress-rupture properties of the Ni3Al-based single crystal alloy. Figure 1 The dislocation configuration diagram of the

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

[0034] The Ni3Al-based single crystal alloy provided by the application contains 1.5-3.6 wt. % Re, which can be specifically 1.5 wt. %, 1.8 wt. %, 2.0 wt. %, 2.3 wt. %, 2.5 wt. %, 2.8 wt. %, 3.0 wt. %, 3.3 wt. % or 3.6 wt. %. In the application, 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, the "Re element cluster effect" is generated, which can significantly hinder the movement of dislocations and improve the high-temperature stress-rupture property. However, if the content of the Re element is too high, the microstructure stability is lost, TCP phases are generated, and the high-temperature stress-rupture property of the material is reduced. Therefore, the content of the Re element needs to be controlled in a proper range.

[0035] The application introduces the synergistic microstructure regulation of the γ-Ni phase, increases the critical shear stress of the APB shear, and improves the ability of the Ni3Al-based single crystal alloy to hinder the movement of dislocations in different orientations. Therefore, the Ni3Al-based single crystal alloy has a wide orientation advantage under super-high temperature conditions.

[0036] The Ni3Al-based single crystal alloy provided by the application contains 0.9-1.8 wt. % Cr, which can be specifically 0.9 wt. %, 1.0 wt. %, 1.3 wt. %, 1.5 wt. % or 1.8 wt. %. In the application, the Cr element mainly improves the oxidation resistance and corrosion resistance of the Ni3Al-based single crystal alloy, but has little contribution to the strength of the Ni3Al-based single crystal alloy. In addition, too much Cr element will sacrifice the high-temperature stress-rupture property of the Ni3Al-based single crystal alloy and generate a large amount of TCP phases during service, which reduces the microstructure stability of the Ni3Al-based single crystal alloy. Therefore, the content of the Cr element also needs to be controlled in a proper range.

[0037] The Ni3Al-based single crystal alloy provided by the application contains the remaining Ni. In the application, the Ni element is a forming element of the γ'-Ni phase and the γ'-Ni3Al phase.

[0038] In the application, the Ni3Al-based single crystal alloy contains the γ'-Ni3Al phase and the γ-Ni phase. The volume fraction of the γ'-Ni3Al phase can be 76-82 vol. %, and the volume fraction of the γ-Ni phase can be 8-24 vol. %. The single crystal orientation of the Ni3Al-based single crystal alloy includes the

[001] orientation, the

[011] orientation or the

[111] orientation.

[0039] The application adopts the organizational design idea of synergistic effect of two-phase structure of gamma'-Ni3Al phase and gamma-Ni phase, adopts the alloying design idea of high Al rich gamma'-Ni3Al phase volume fraction and high Ta strong gamma'-Ni3Al phase, so as to improve the super-high temperature thermal stability of gamma'-Ni3Al phase. At the same time, combined with the high mismatch degree alloying synergistic regulation design of Mo instead of Re, the mismatch degree of gamma'-Ni3Al and gamma-Ni phase is fully regulated, the interface dislocation network density is increased, the organizational stability at super-high temperature is enhanced, and the temperature resistance of Ni3Al-based single crystal alloy is also significantly improved.

[0040] The gamma'-Ni3Al phase is the most effective strengthening phase at high temperature, which significantly hinders the movement of dislocation. Since the gamma'-Ni3Al phase will significantly dissolve at 1200 DEG C super-high temperature, the volume fraction of gamma'-Ni3Al phase of the mainstream generation single crystal alloy at home and abroad decreases significantly, and the super-high temperature temperature resistance decreases significantly. The Ni3Al-based single crystal alloy provided by the application adopts two-phase structure, and the gamma'-Ni3Al phase is the main body, and the gamma-Ni phase is synergistic. The design of rich gamma'-Ni3Al phase volume fraction and strong gamma'-Ni3Al phase is helpful to improve the thermal stability of gamma'-Ni3Al phase at super-high temperature, and increase the organizational stability of Ni3Al-based single crystal alloy at super-high temperature. At super-high temperature, the dislocation movement is mainly APB shearing gamma'-Ni3Al phase, and the critical shearing stress required for APB shearing is as follows:

[0041]

[0042] Wherein d is the size of gamma'-Ni3Al phase, it is not difficult to see that the critical shearing stress required for APB shearing is inversely proportional to the size of gamma'-Ni3Al phase. The size of pure single-phase gamma'-Ni3Al phase is large, and the critical shearing stress required for APB shearing is small, which cannot effectively hinder the movement of dislocation. Therefore, a small amount of gamma-Ni phase is introduced to improve the precipitation size and morphology of gamma'-Ni3Al phase, increase the critical shearing stress required for APB shearing, and at the same time, the introduction of gamma-Ni phase can increase the two-phase mismatch degree, form the interface dislocation network at high temperature, enhance the mismatch strengthening effect, significantly hinder the dislocation, and improve the super-high temperature strength of Ni3Al-based single crystal alloy.

[0043] The application also provides a preparation method of the Ni3Al-based single crystal alloy.

[0044] The materials are mixed according to the element ratio to carry out smelting, and a master alloy is prepared;

[0045] The master alloy is remelted and directionally solidified according to the seed crystal method to obtain different orientation single crystal alloys;

[0046] The different orientation single crystal alloy is sequentially subjected to solid solution treatment and aging treatment, so that the Ni3Al-based single crystal alloy is obtained.

[0047] According to the element ratio, the material is mixed and smelted to obtain the master alloy. As a specific embodiment of the present application, the smelting can be vacuum induction smelting. The present application does not have special limitation on the vacuum induction smelting, and the smelting can be carried out according to the conventional manner in the art.

[0048] After obtaining the master alloy, the master alloy is remelted and directionally solidified according to the seed crystal method to obtain the different orientation single crystal alloy. As a specific embodiment of the present application, the preparation method of the single crystal rod wax mold used in the process of directionally solidifying according to the seed crystal method can include the following steps: placing the seed crystal in the seed crystal wax mold and pressing to obtain the single crystal rod wax mold; the orientation of the seed crystal can include

[001] orientation,

[011] orientation or

[111] orientation; the temperature of the pressing can be 45-70℃, and can be specifically 45℃, 50℃, 55℃, 60℃, 65℃ or 70℃; the pressure of the pressing can be 6-15MPa, and can be specifically 6MPa, 8MPa, 10MPa, 12MPa or 15MPa; the pressure holding time of the pressing can be 10-30s, and can also be 15-25s, and can be specifically 10s, 15s, 20s, 25s or 30s. As a specific embodiment of the present application, the pressing can be carried out in a high-pressure injection machine.

[0049] As a specific embodiment of the present application, the pulling rate of the directionally solidified crystal can be 1-5mm / s, and can also be 2-4mm / s, and can be specifically 1mm / s, 1.5mm / s, 2mm / s, 2.5mm / s, 3mm / s, 3.5mm / s, 4mm / s, 4.5mm / s or 5mm / s. According to the present application, the seed crystal method is used for crystal type directionally solidified, and the pulling rate is limited in the above range, so that the Ni3Al-based single crystal alloy with

[001] orientation,

[011] orientation or

[111] orientation can be prepared.

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

[0051] As a specific embodiment of the present application, the solid solution treatment can further include cooling the product after the solid solution treatment to room temperature; the cooling method can be air cooling, and the temperature of the room temperature can be 20-30 DEG C.

[0052] As a specific embodiment of the present application, the aging treatment includes sequentially performing primary aging treatment and secondary aging treatment; the temperature of the primary aging treatment can be 1000-1100 DEG C, and can be specifically 1000 DEG C, 1010 DEG C, 1020 DEG C, 1030 DEG C, 1040 DEG C, 1050 DEG C, 1060 DEG C, 1070 DEG C, 1080 DEG C, 1090 DEG C or 1100 DEG C; the holding time of the primary aging treatment can be 2-4 h, and can be specifically 2 h, 2.5 h, 3 h, 3.5 h or 4 h. As a specific embodiment of the present application, the primary aging treatment can further 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 DEG C.

[0053] As a specific embodiment of the present application, the temperature of the secondary aging treatment can be 850-900 DEG C, and can be specifically 850 DEG C, 860 DEG C, 870 DEG C, 880 DEG C, 890 DEG C or 900 DEG C; the holding time of the secondary aging treatment can be 30-34 h, and can be specifically 30 h, 31 h, 32 h, 33 h or 34 h. As a specific embodiment of the present application, the secondary aging treatment can further 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 DEG C.

[0054] The primary aging treatment can adjust the morphology, size and cubic degree of the γ' phase, and the secondary aging treatment can adjust the cubic degree of the γ' phase.

[0055] The application further provides application of the Ni3Al-based single crystal alloy or the Ni3Al-based single crystal alloy prepared by the preparation method in preparation of a turbine of an aero-engine. The Ni3Al-based single crystal alloy has the advantages of low cost, high temperature resistance and wide orientation, and is suitable for a high-pressure turbine guide vane and a high-pressure turbine outer ring of an advanced aero-engine.

[0056] In order to further illustrate the application, the technical solutions provided by the application are described in detail below in combination with examples, but they should not be understood as limiting the protection scope of the application.

[0057] Example 1

[0058] Master alloy smelting: according to the element ratio, the raw materials for alloying are weighed, and a master alloy is prepared by smelting in a vacuum induction melting furnace;

[0059] Single crystal rod wax mold pressing: the

[001] oriented seed crystal is placed in a seed crystal wax mold, a high-pressure injection machine is used to press the seed crystal wax mold, the pressing pressure is 10 MPa, the holding time of pressing is 20 s, and the pressing temperature is 50 DEG C;

[0060] Directional solidification according to the seed crystal method: the master alloy is remelted and poured by using a single crystal furnace, and a

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

[0061] Heat treatment: the

[001] oriented single crystal alloy rod is subjected to solid solution treatment at 1320 DEG C for 20 h, and then air-cooled to 25 DEG C; the product after the solid solution treatment is subjected to primary aging treatment at 1050 DEG C for 3 h, and then air-cooled to 25 DEG C; the product after the primary aging treatment is subjected to secondary aging treatment at 880 DEG C for 33 h, and then air-cooled to 25 DEG 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, 3wt.%Re, 1.5wt.%Cr and the balance of Ni.

[0062] Example 2

[0063] The 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 balance of Ni.

[0064] Example 3

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

[001] oriented seed crystal was replaced by a

[111] oriented seed crystal to obtain a

[111] oriented Ni3Al-based single crystal alloy, and the element content of the

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

[0066] Comparative Example 1

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

[0068] Comparative Example 2

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

[0070] Comparative Example 3

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

[0072] The Ni3Al-based single crystal alloys prepared in Examples 1-3 were detected by a metallographic microscope, and microstructure images were obtained, as shown in Figures 2 to 4 , wherein Figure 2 is a microstructure image of the

[001] oriented Ni3Al-based single crystal alloy, Figure 3 is a microstructure image of the

[011] oriented Ni3Al-based single crystal alloy, Figure 4 is a microstructure image of the

[111] oriented Ni3Al-based single crystal alloy. From Figures 2 to 4 It can be seen that after heat treatment, the two-phase structure of the Ni3Al-based single crystal alloys with different orientations is completely solid-solved, and there is no initial melting, incomplete solid-solution and the like; Figure 2The microstructure of the

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

[011] oriented Ni3Al-based single crystal alloy presents a rectangular shape. 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 inconvenient to count.

[0073] The single crystal alloys of Examples 1-3 and Comparative Examples 1-3 were placed under the condition of a temperature of 1200℃ and a pressure of 80 MPa for the detection of the stress-rupture property (the time of fracture of the sample was recorded), and the results are shown in Table 1.

[0074] Table 1: The fracture time of the single crystal alloys of Examples 1-3 and Comparative Examples 1-3 under high temperature and high pressure

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

[0076] A columnar comparison chart of the fracture time of the single crystal alloys of Examples 1-3 and Comparative Examples 1-3 under the condition of a temperature of 1200℃ and a pressure of 80 MPa was drawn according to Table 1, as shown in Figure 5 It can be seen from Table 1 and Figure 5 It can be seen that the Ni3Al-based single crystal alloy provided by the present application has a long fracture time under high temperature and high pressure, which indicates that it has good high-temperature and high-pressure resistance.

[0077] The microstructure stability of the Ni3Al-based single crystal alloy provided by the present application is significantly improved at a service temperature of 1200℃, and in particular, the γ' phase has excellent thermal stability. The stability of the microstructure of the single crystal alloy at a temperature of 1200℃ and above is mainly that the γ' phase will undergo strong re-dissolution, resulting in a rapid decrease in the content of the γ'-Ni3Al phase. For example, the content of the γ'-Ni3Al phase of Rene N5 alloy after thermal equilibrium at 1200℃ is only 45%, which is about 25% less than that at 1150℃; similarly, the content of the γ'-Ni3Al phase of MC-NG alloy after thermal equilibrium at 1200℃ rapidly decreases from 60% (after thermal equilibrium at 1100℃) to less than 50%. The Ni3Al-based single crystal alloy provided by the present application adopts the design idea of rich γ' phase volume fraction and strong γ' phase, successfully controls and prepares a single crystal intermetallic compound with excellent microstructure stability at a service temperature of 1200℃, and the service results show that the volume fraction of the alloy is as high as 65 vol.% or more at 1200℃.

[0078] The Ni3Al-based single crystal alloy provided by the application has super-high temperature stress-rupture performance, especially 1200℃ / 80MPa stress-rupture life. For example, the fourth generation single crystal alloy MC-NG has a stress-rupture life of more than 150h at 1150℃ / 100MPa, and is reduced to 15h at 1200℃ / 100MPa. The

[001] oriented Ni3Al-based single crystal alloy provided by the application has a stress-rupture life of 159h at 1200℃ / 80MPa, which is 10 times of the stress-rupture life of the fourth generation single crystal alloy.

[0079] The Ni3Al-based single crystal alloy provided by the application has a wide orientation advantage at super-high temperature, that is, excellent high-temperature stress-rupture performance at each orientation. The Ni3Al-based single crystal alloy developed by the application has a significant advantage at the

[001] orientation, and the stress-rupture life of the

[011] and

[111] oriented Ni3Al-based single crystal alloy is up to 150.8h and 190h at 1200℃ / 80MPa.

[0080] Although the above embodiment has described the application in detail, it is only a part of the embodiments of the application, not all the embodiments, and other embodiments can be obtained according to the embodiment without creativity, which all belong to the protection scope of the application.

Claims

1. A Ni3Al-based single-crystal alloy, characterized in that, The following elemental components are included in the following mass percentages: Al 7.4wt.%; Ta 4wt.%% Mo 9.5wt.%; Re 3%wt.%; Cr 1.5wt.%; Ni balance; The Ni3Al-based single crystal alloy comprises a γ'-Ni3Al phase and a γ-Ni phase; 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.%. The preparation method of the Ni3Al-based single crystal alloy includes the following steps: The materials are mixed and smelted according to the element ratio to prepare the master alloy; The master alloy was remelted and then directionally solidified using the seed crystal method to obtain single crystal alloys with different orientations. The different orientation single crystal alloys were subjected to solution treatment and aging treatment in sequence to obtain the Ni3Al-based single crystal alloy; the solution treatment temperature was 1300~1330℃ and the holding time was 20~30h.

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

3. The method for preparing the Ni3Al-based single-crystal alloy according to claim 1 or 2, characterized in that, Includes the following steps: The materials are mixed and smelted according to the element ratio to prepare the master alloy; The master alloy was remelted and then directionally solidified using the seed crystal method to obtain single crystal alloys with different orientations. The different oriented single crystal alloys were subjected to solution treatment and aging treatment in sequence to obtain the Ni3Al-based single crystal alloy; the solution treatment temperature was 1300~1330℃ and the holding time was 20~30h.

4. The preparation method according to claim 3, characterized in that, The timeliness processing includes first-level timeliness processing and second-level timeliness processing performed sequentially.

5. The preparation method according to claim 4, characterized in that, The temperature for the first-stage aging treatment is 1000~1100℃, and the holding time is 2~4h; The temperature for the secondary aging treatment is 850~900℃, and the holding time is 30~34h.

6. The preparation method according to claim 3, characterized in that, The method for preparing the single crystal rod wax mold used in the directional solidification process according to the seed crystal method includes the following steps: placing the seed crystal in the seed crystal wax mold and pressing it 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 45~70℃, the pressing pressure is 6~15MPa, and the pressing holding time is 10~30s.

7. The preparation method according to claim 3 or 6, characterized in that, The crystal pulling rate of the directional solidification is 1~5 mm / s.

8. The application of the Ni3Al-based single crystal alloy according to claim 1 or 2 or the Ni3Al-based single crystal alloy prepared by the preparation method according to any one of claims 3 to 7 in the preparation of aero-engine turbines.

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