Heat treatment method of high-temperature alloy and powder high-temperature alloy

Abstract

The invention discloses a heat treatment method of a high-temperature alloy and a powder high-temperature alloy, and relates to the technical field of high-temperature alloy preparation. The heat treatment method comprises the following steps: S1, carrying out heat preservation on the powder high-temperature alloy at a solution treatment temperature Tsol for 0-8 hours; s2, the alloy is cooled to (Tgamma '-30 DEG C)-(Tgamma'-150 DEG C) at the cooling rate of 30-80 DEG C / min; s3, the alloy is cooled to the room temperature at the cooling rate of 100-600 DEG C / min; and S4, keeping the temperature at 760-815 DEG C for 4-24 hours, and then cooling to room temperature. The strength and plasticity of the powder high-temperature alloy at the high temperature are effectively and synergistically improved, optimal configuration of the tensile property of different parts of the turbine disc at the high temperature (such as 800 DEG C) is achieved, the overall strength and local plasticity are considered, and the high-temperature alloy can be manufactured on the premise that components are not greatly changed and the cost is not remarkably increased. The contradiction between strength and plasticity in traditional heat treatment is broken through, and a low-cost and high-performance regulation and control way is provided for high-end equipment manufacturing.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high-temperature alloy preparation, and particularly relates to a heat treatment method of high-temperature alloy and a powder high-temperature alloy. BACKGROUND

[0002] The application of powder metallurgy technology in the field of turbine disc preparation effectively overcomes the macrosegregation problem caused by the traditional casting and forging process, and provides an important guarantee for the uniformity of the microstructure of high-performance nickel-based high-temperature alloy. With the continuous improvement of the working temperature of the aero-engine and gas turbine, more stringent requirements are put forward for the turbine disc to simultaneously maintain high strength and high plasticity in a high-temperature environment. At present, through solid solution treatment combined with a high cooling rate continuous cooling process, fine γ' phases can be formed in the alloy in a dispersed distribution, thereby achieving significant strength improvement. However, due to the common strength-plasticity inversion relationship in metal materials, this process often leads to a significant decrease in plasticity, which limits the application reliability of the alloy in extreme environments.

[0003] The inversion relationship between strength and plasticity is essentially caused by the insufficient work hardening capacity of the material during deformation. When the work hardening rate cannot match the increase of the flow stress, strain localization and early necking are easily caused, thereby leading to plastic instability. Therefore, the key to improving the high-temperature plasticity of the high-temperature alloy lies in enhancing the uniform deformation capacity and work hardening rate of the alloy. Current research shows that through phase transformation induced plasticity, twinning induced plasticity, grain refinement regulation, main element composition optimization and precipitate phase morphology design, the dislocations can be uniformly wound, proliferated and stored during deformation, which is an effective way to improve the plasticity.

[0004] Further from the alloy composition system, although the typical third-generation powder high-temperature alloy (such as FGH4113A, FGH98, FGH99, ME3 and LSHR) has similar phase transformation mechanisms and strengthening mechanisms with similar proportions of main strengthening elements such as Al, Co, Cr, Mo, W, Ti, Nb and Ta, it shows that the plasticity improvement strategy has universality within a certain range. However, the current method for achieving the coordinated improvement of strength and plasticity still mainly relies on adjusting the main element composition of the alloy or optimizing the heat treatment process, which not only significantly increases the research and development cycle and manufacturing cost, but also increases the process complexity.

[0005] In particular, in the heat treatment link, the traditional process focuses on controlling the size and distribution of γ' phases through rapid continuous cooling to strengthen the alloy, but it is difficult to avoid the contradiction between strength and plasticity. Therefore, how to break through the existing performance bottleneck through process innovation under the premise of not significantly increasing the cost, and develop a new heat treatment method that can simultaneously improve the strength and plasticity of the powder high-temperature alloy, has become a core technical problem to be solved in the field. SUMMARY

[0006] The technical problem solved by the present application is that it is difficult to balance high temperature strength and plasticity in the heat treatment method of conventional high temperature alloys.

[0007] To solve the above problems, the present application proposes the following technical solutions:

[0008] The present application provides a heat treatment method of high temperature alloy, comprising the following steps:

[0009] S1, the powder high temperature alloy is treated at a solid solution temperature T sol for 0-8 hours;

[0010] S2, the alloy is cooled to (T γ' -30℃)~(T γ' -150℃) at a cooling rate of 30-80℃ / min, wherein T γ' is the complete solid solution temperature of the gamma prime phase of the powder high temperature alloy;

[0011] S3, the powder high temperature alloy is cooled to room temperature at a cooling rate of 100-600℃ / min;

[0012] S4, the powder high temperature alloy is cooled to room temperature after being kept at 760-815℃ for 4-24 hours.

[0013] Further technical solutions are that T sol is (T γ' -15℃)~(T γ' +50℃).

[0014] Further technical solutions are that T sol is (T γ )~(T γ' +30℃).

[0015] Further technical solutions are that in the step S2, the alloy is cooled to (T γ' -50℃)~(T γ' -70℃) at a cooling rate of 30-80℃ / min.

[0016] Further technical solutions are that the room temperature mole ratio of the gamma prime phase in the powder high temperature alloy is 45-60%.

[0017] Further technical solutions are that in the step S1, the grain size of the alloy increases to 6.5-9.5 levels after the solid solution treatment.

[0018] Further, the equivalent diameter of the large-size gamma prime phase in the alloy obtained after the heat treatment method is 1-5 microns; the equivalent diameter of the medium-size gamma prime phase is 100-300 nanometers; and the equivalent diameter of the small-size gamma prime phase is 10-70 nanometers.

[0019] Further, the heat treatment method is suitable for treating a powder high-temperature alloy containing Co 16-21.5 wt.%, Cr 12-14 wt.%, Al+Ti 6-8 wt.%, 2*Nb+Ta 2-6 wt.%, 2*Mo+W 8-12 wt.%, and the rest being grain boundary strengthening elements: C, B, Hf, Zr.

[0020] The application further provides a preparation method of a powder high-temperature alloy, which comprises the heat treatment method of the high-temperature alloy.

[0021] The application further provides a powder high-temperature alloy prepared by the preparation method of the powder high-temperature alloy, wherein the equivalent diameter of the large-size gamma prime phase in the powder high-temperature alloy is 1-5 microns; the equivalent diameter of the medium-size gamma prime phase is 100-300 nanometers; and the equivalent diameter of the small-size gamma prime phase is 10-70 nanometers.

[0022] Compared with the prior art, the application can achieve the following technical effects:

[0023] The heat treatment method of the high-temperature alloy provided by the application effectively improves the strength and plasticity of the powder high-temperature alloy at high temperature through the multi-stage precise temperature control heat treatment process. The application first performs heat preservation at a near-solution or over-solution temperature, promotes moderate grain coarsening, reduces the overall proportion of grain boundaries, thereby significantly inhibiting the deformation mechanism dominated by grain boundary sliding and diffusion creep at high temperature, and improves the creep resistance and high-temperature stability of the material. In the cooling stage after solution, the application adopts a segmented cooling strategy: in the first stage, the temperature is slowly reduced to a preset temperature below the gamma prime phase solution temperature, so that the first batch of gamma prime phases is slowly precipitated and appropriately grown; then in the second stage, rapid cooling is applied to supplement the second batch of gamma prime phases with small size and uniform distribution in the gamma channel. This precise cooling control process effectively controls the precipitation behavior and distribution form of the gamma prime phase, reduces the risk of disc cracking caused by instantaneous high thermal stress, and improves the reliability and yield of the processing technology.

[0024] The application can also realize the optimal configuration of the tensile properties of different parts of the turbine disc at high temperature (such as 800 DEG C), taking into account the overall strength and local plasticity, breaking through the contradiction between strength and plasticity in traditional heat treatment, and providing a low-cost and high-performance regulation method for high-end equipment manufacturing.

[0025] The heat treatment method of the high-temperature alloy provided by the application can successfully construct a microstructure with multiple-scale γ' precipitated phases in the third-generation powder high-temperature alloy turbine disc by introducing a multi-stage precise temperature control heat treatment process. The method effectively coordinates the strengthening and toughening effects of precipitated γ' phases of different sizes, thereby improving the high-temperature strength while significantly improving the plasticity, and successfully solves the contradiction between high-temperature strength and plasticity in the traditional heat treatment process.

[0026] The heat treatment method of the high-temperature alloy provided by the application is essentially to realize the synergistic improvement of strength and plasticity by precisely regulating the size and distribution of γ' phases in the alloy, and is generally applicable to all third-generation powder high-temperature alloys with γ' phases as the main strengthening phase, and has wide engineering applicability and popularization value. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 DTA differential thermal analysis cooling curve of the powder high-temperature alloy FGH4113A used in the examples and comparative examples of the application.

[0028] Figure 2 The relationship between the γ' phase proportion in the FGH4113A alloy and the temperature calculated by the phase diagram calculation method (CALPHAD).

[0029] Figure 3 The forged metallographic photos of the FGH4113A alloy used in the examples and comparative examples in the application.

[0030] Figure 4 The EBSD inverse pole figure of the FGH4113A alloy used in the examples and comparative examples in the application.

[0031] Figure 5 The electrolytic corrosion photo of Example 2.

[0032] Figure 6 The electrolytic corrosion photo of Example 3.

[0033] Figure 7 The electrolytic corrosion photo of Example 6.

[0034] Figure 8 The electrolytic corrosion photo of Comparative Example 1.

[0035] Figure 9 The average sizes of the second and third γ' phases after solid solution treatment of the comparative examples and part of the examples calculated by using the thermodynamic software package Pandat.

[0036] Figure 10 The volume fractions of the second, third and aging γ' phases after complete heat treatment of the comparative examples and part of the examples calculated by using the thermodynamic software package Pandat. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the following described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0038] It should be understood that the terms "comprising" and "including" as used in the specification and the appended claims indicate the presence of the described features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0039] It should also be understood that the terms used in the specification of the embodiments of the present application are only for the purpose of describing specific embodiments and are not intended to limit the embodiments of the present application. As used in the specification and the appended claims of the embodiments of the present application, the singular forms "a", "an" and "the" are intended to include the plural forms unless the context clearly indicates otherwise.

[0040] The embodiments of the present application aim at the problem that the high-temperature strength and plasticity of a powder superalloy turbine disc after hot isostatic pressing, hot extrusion and isothermal forging are difficult to be balanced, and provide a heat treatment method of a superalloy, comprising the following steps:

[0041] S1, solid solution treatment of the powder superalloy at a solid solution treatment temperature T sol holding for 0-8 hours.

[0042] Through the solid solution treatment, the large-size γ' phase generated in the powder superalloy manufacturing process (hot isostatic pressing, hot extrusion and isothermal forging process) is reduced or completely dissolved, the pinning of the γ' phase to the grain boundary is reduced and the large-size γ' phase is avoided to remain after the heat treatment. At the same time, through the solid solution treatment, the grain can be coarsened moderately, the total proportion of the grain boundary is reduced, thereby the deformation mechanism dominated by the grain boundary sliding and diffusion creep at high temperature is inhibited, and the creep resistance and high-temperature stability of the material are improved. Therefore, the solid solution treatment temperature T sol is close to or greater than the complete solid solution temperature T γ' of the γ' phase of the powder superalloy.

[0043] In a specific implementation, the complete solid solution temperature T γ' of the γ' phase of the powder superalloy is determined by using differential thermal analysis (DTA), differential scanning calorimetry (DSC), phase diagram calculation (CALPHAD) or metallographic method.

[0044] In a specific embodiment, the grain size of the powder superalloy is increased to 6.5-9.5, preferably 7.5-8.5, by solution treatment.

[0045] In a specific embodiment, the solution treatment temperature T sol is (T γ' -15℃) to (T γ' +50℃), and is not more than (T γ' +50℃) to avoid abnormal grain growth. Preferably, T sol is (T γ ) to (T γ' +30℃).

[0046] S2, cooling the powder superalloy at a cooling rate of 30-80℃ / min to (T γ' -30℃) to (T γ' -150℃).

[0047] The alloy is cooled to the complete solution temperature T γ' at a cooling rate of 30-80℃ / min using a conventional air furnace or vacuum air quenching furnace, and using cooling methods such as air cooling, air cooling, vacuum air cooling, etc. The following specific temperatures, such as (T γ' -30℃ to (T γ' -150℃), preferably (T γ' -50℃) to (T γ' -70℃), allow the slow precipitation and proper growth of the first batch of γ' phase (referred to as secondary γ').

[0048] S3, cooling the powder superalloy at a cooling rate of 100-600℃ / min to room temperature.

[0049] By adjusting parameters such as charging pressure or fan speed, the cooling rate is increased to 100-600℃ / min to supplement the second batch of γ' phase (referred to as tertiary γ') in the γ channel, which is small in size and uniformly distributed. Preferably, the cooling rate is 250-350℃ / min.

[0050] It should be noted that the specific temperature in step S2 is measured by a welding thermocouple. In some embodiments, according to simulation calculation, the specific temperature is indirectly controlled by controlling the cooling time (cooling rate) of step S2 to realize the optimization of the distribution of γ' phase of different sizes by combining slow cooling and fast cooling.

[0051] It can be understood that the powder superalloy, such as the nickel-based superalloy for turbine disk, the γ' phase precipitation kinetics determines that the precipitation is in batches, so it also presents the characteristics of batch precipitation under the conventional continuous cooling process. In the present application, the first stage is slow cooling, the temperature is high, and the precipitated secondary γ' phase has a large size, and the second stage is fast cooling, the temperature drops fast, and the precipitated tertiary γ' phase has a small size.

[0052] S4, the powder superalloy is cooled to room temperature after being kept at 760-815℃ for 4-24 hours.

[0053] This stage is also called aging treatment, which can be carried out in a conventional air furnace or a vacuum air quenching furnace, and the cooling method can use furnace cooling, air cooling, gas cooling or oil cooling. The aging treatment can consume the excess solid solubility in the matrix and supplement the aging γ' phase (called aging γ') with small size and uniform distribution. Preferably, the aging treatment system is 760℃ for 16 hours or 815℃ for 8 hours.

[0054] The heat treatment method of the superalloy provided by the present application essentially realizes the synergistic improvement of strength and plasticity by precisely controlling the size and distribution of the γ' phase in the alloy, so the heat treatment method of the present application is generally applicable to all third-generation powder superalloys with γ' phase as the main strengthening phase. For example, the powder superalloys in Table 1 below.

[0055] Table 1 Composition of powder superalloy (wt. %)

[0056] Al Co Cr Mo Nb Ti W Ta Ni 2*Al+Ti 2*Nb+Ta 2*Mo+W FGH4113A 3.0 19.0 13.0 4.0 1.2 3.7 4.0 1.0 Bal. 9.7 3.4 12 FGH98 3.5 20.4 12.7 3.8 0.9 3.7 2.1 2.4 Bal. 10.7 4.2 9.7 FGH99 3.6 20.0 13.0 2.9 1.5 3.5 4.3 1.5 Bal. 10.7 4.5 10.1 ME3 3.4 20.6 13.0 3.8 0.9 3.7 2.1 2.4 Bal. 10.5 4.2 9.7 LSHR 3.5 21.0 13.0 2.7 1.5 3.5 4.3 1.6 Bal. 10.5 4.6 9.7

[0057] In order to clearly show the actual effect of the present application, the following examples and comparative examples all use the third-generation powder superalloy FGH4113A which has undergone the same hot forming and hot deformation process, and the initial average grain size is 8-9 grade, and the forged state metallographic photos and EBSD inverse pole figure are shown in Figure 3 、 Figure 4 .

[0058] The DTA differential thermal analysis cooling curve of the extruded state alloy of FGH4113A is shown in Figure 1 , and the relationship between the proportion of γ' phase in FGH4113A alloy and temperature calculated by phase diagram calculation method (CALPHAD) is shown in Figure 2 .

[0059] Example 1

[0060] The present application provides a heat treatment method of superalloy, which improves the strength and plasticity of the turbine disk of FGH4113A powder superalloy by heat treatment. The specific steps are as follows:

[0061] (1) Using a conventional heat treatment furnace, ramp to 1175 ± 10°C at a rate of no more than 10°C / min, hold for 2.5 hours.

[0062] (2) Cool the alloy to 1065 ± 10°C at a rate of about 44°C / min.

[0063] (3) Cool the alloy to room temperature at a rate of about 459°C / min.

[0064] (4) Aging heat treatment: hold at 815°C for 8 hours, air cool.

[0065] Example 2

[0066] (1) Using a conventional heat treatment furnace, ramp to 1175 ± 10°C at a rate of no more than 10°C / min, hold for 2.5 hours.

[0067] (2) Cool the alloy to 1020 ± 10°C at a rate of about 75°C / min.

[0068] (3) Cool the alloy to room temperature at a rate of about 594°C / min.

[0069] (4) Aging heat treatment: hold at 815°C for 8 hours, air cool.

[0070] Example 3

[0071] (1) Using a conventional heat treatment furnace, ramp to 1175 ± 10°C at a rate of no more than 10°C / min, hold for 2.5 hours.

[0072] (2) Cool the alloy to 1100 ± 10°C at a rate of about 65°C / min.

[0073] (3) Cool the alloy to room temperature at a rate of about 295°C / min.

[0074] (4) Aging heat treatment: hold at 815°C for 8 hours, air cool.

[0075] Example 4

[0076] (1) Using a conventional heat treatment furnace, ramp to 1175 ± 10°C at a rate of no more than 10°C / min, hold for 2.5 hours.

[0077] (2) Cool the alloy to 1090 ± 10°C at a rate of about 50°C / min.

[0078] (3) Cool the alloy to room temperature at a rate of about 197°C / min.

[0079] (4) Aging heat treatment: hold at 815°C for 8 hours, air cool.

[0080] Example 5

[0081] (1) Using a conventional heat treatment furnace, the alloy was heated to 1175 ± 10 °C at a rate of not more than 10 °C / min, and held for 2.5 hours.

[0082] (2) The alloy was cooled to 1090 ± 10 °C at a cooling rate of about 61 °C / min.

[0083] (3) The alloy was cooled to room temperature at a cooling rate of about 181 °C / min.

[0084] (4) Aging heat treatment: holding at 815 °C for 8 hours, air cooling.

[0085] Example 6

[0086] (1) Using a conventional heat treatment furnace, the alloy was heated to 1175 ± 10 °C at a rate of not more than 10 °C / min, and held for 2.5 hours.

[0087] (2) The alloy was cooled to 1090 ± 5 °C at a cooling rate of about 51 °C / min.

[0088] (3) The alloy was cooled to room temperature at a cooling rate of about 121 °C / min.

[0089] (4) Aging heat treatment: holding at 815 °C for 8 hours, air cooling.

[0090] Comparative Example 1

[0091] (1) Using a conventional heat treatment furnace, the alloy was heated to 1175 ± 10 °C at a rate of not more than 10 °C / min, and held for 2.5 hours.

[0092] (2) The alloy was cooled to room temperature at a cooling rate of about 150 °C / min.

[0093] (3) Aging heat treatment: holding at 815 °C for 8 hours, air cooling.

[0094] The alloys FGH4113A after heat treatment of Examples 1-6 and Comparative Example 1 were subjected to relevant performance tests at 800 °C, and the results are shown in Table 2. The electrolytic corrosion photos of Example 2, 3, 6 are shown in Figures 5 to 7 The electrolytic corrosion photo of Comparative Example 1 is shown in Figure 8 The results of the average size of γ' phase and the volume fraction of γ' phase under different treatment processes are shown in Figure 9 and Figure 10 .

[0095] It can be seen that the total amount of the three γ' phases and the aging γ' phases of the comparative example is less, indicating that the conventional cooling treatment cannot flexibly adjust the size distribution of the γ' phase. The size of the secondary γ' phase of the embodiments is affected by the cooling rate of the first stage, and increases as the cooling rate decreases, and the volume fraction is affected by the specific transition temperature, and increases as the transition temperature decreases. In addition, the content of small size (including tertiary γ' and aging γ') γ' phase of the embodiments is more, the proportion of the tertiary γ' phase increases as the specific transition temperature increases, and the size of the tertiary γ' phase decreases as the cooling rate of the second stage increases. Obviously, by controlling the cooling rate, the size distribution of the γ' phase in the turbine disc can be effectively adjusted.

[0096] Table 2 Alloy performance after heat treatment of examples 1-6 and comparative example 1

[0097]

[0098]

[0099] As can be seen from the results in Table 2, compared with the comparative example 1 using the traditional continuous cooling process (about 150℃ / min), the plasticity indicators of all the embodiments are significantly improved while maintaining high strength. Among them, examples 1 to 4 effectively control the size distribution and volume fraction of the γ' phase by adjusting the cooling rate of the first stage (about 50-75℃ / min), the specific cooling temperature (1020-1090℃) and the cooling rate of the second stage (121-594℃ / min), thereby optimizing the performance matching. With the increase of the cooling rate of the second stage, the tensile strength of the alloy decreases slightly from the highest 987MPa to 924MPa, with a maximum decrease of only 6.4%, while the elongation after fracture increases significantly from the lowest 14.5% to 27%, with a maximum increase of 107.7%. This trend shows that the process of the present application can significantly improve the high temperature plasticity of the material with little loss of strength.

[0100] In combination with Figure 9 and Figure 10 It can be seen that the heat treatment method of the high-temperature alloy provided by the present application can effectively control the precipitation behavior and size distribution of the γ' phase, which helps to improve the dislocation storage capacity and work hardening rate, thereby synergistically enhancing the high-temperature strength and plasticity of the material.

[0101] The heat treatment method of the high-temperature alloy provided by the present application has good controllability and stability, and can realize the synergistic design of the strength and plasticity of the high-temperature alloy by optimizing the γ' phase organization, solving the problem that the two are difficult to be considered in the traditional process, and having important engineering application value.

[0102] In the above embodiments, the description of each embodiment has its own emphasis, and the parts not described in detail in a certain embodiment can be referred to the related description of other embodiments.

[0103] The above is a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto, and any person skilled in the art can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present application, and these modifications or replacements should be covered within the scope of protection of the present application. Therefore, the scope of protection of the present application should be subject to the scope of protection of the claims.

Claims

1. A heat treatment method for a high-temperature alloy, characterized in that, Includes the following steps: S1, the powder superalloy is subjected to a solution treatment temperature T sol Keep warm for 0-8 hours; S2. Cool the alloy to (T) at a cooling rate of 30–80 °C / min. γ' -30℃~(T γ' -150℃), where T γ' The complete solid solution temperature of the γ' phase in powder superalloys; S3. Cool the powder superalloy to room temperature at a cooling rate of 100-600℃ / min; S4. Hold the powdered high-temperature alloy at 760-815℃ for 4-24 hours, then cool it to room temperature.

2. The heat treatment method for high-temperature alloys as described in claim 1, characterized in that, T sol For (T) γ' -15℃~(T γ' +50℃).

3. The heat treatment method for high-temperature alloys as described in claim 2, characterized in that, T sol For (T) γ )~(T γ' +30℃).

4. The heat treatment method for high-temperature alloys as described in claim 1, characterized in that, In step S2, the alloy is cooled to (T) at a cooling rate of 30–80 °C / min. γ' -50℃~(T γ' -70℃).

5. The heat treatment method for high-temperature alloys as described in claim 1, characterized in that, The room temperature molar percentage of the γ' phase in the powder superalloy is 45-60%.

6. The heat treatment method for high-temperature alloys as described in claim 1, characterized in that, In step S1, after solution treatment, the grain size in the alloy increases to level 6.5 to 9.

5.

7. The heat treatment method for high-temperature alloys as described in claim 1, characterized in that, After the heat treatment method described above, the final alloy has an equivalent diameter of 1–5 μm for the large-sized γ' phase, 100–300 nm for the medium-sized γ' phase, and 10–70 nm for the small-sized γ' phase.

8. The heat treatment method for high-temperature alloys as described in claim 1, characterized in that, The heat treatment method is applicable to powder superalloys containing the following elements: Co 16-21.5 wt.%, Cr 12-14 wt.%, Al+Ti 6-8 wt.%, 2*Nb+Ta 2-6 wt.%, 2*Mo+W 8-12 wt.%, and the remainder being grain boundary strengthening elements: C, B, Hf, Zr.

9. A method for preparing powder superalloys, characterized in that, The heat treatment method for high-temperature alloys as described in any one of claims 1-8.

10. A powder superalloy, characterized in that, The powder superalloy prepared by the preparation method described in claim 9 has the following characteristics: the equivalent diameter of the large-size γ' phase is 1–5 μm; the equivalent diameter of the medium-size γ' phase is 100–300 nm; and the equivalent diameter of the small-size γ' phase is 10–70 nm.

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