Preparation method of powder metallurgy prefabricated part for nickel-based superalloy damage defect shape remodeling and prefabricated part

Abstract

The invention discloses a preparation method of a powder metallurgy prefabricated part for nickel-based superalloy damage defect shape remodeling and the prefabricated part, and the preparation method specifically comprises the following steps that S1, alloy powder for preparing the prefabricated part and a crucible for containing the alloy powder are prepared, and the alloy powder comprises, by weight, 30%-50% of low-melting-point alloy powder and 50%-70% of high-melting-point alloy powder; s2, low-melting-point alloy powder is placed at the bottom of a crucible, and jolt ramming and jolt flattening are carried out in a vibration mode; s3, the high-melting-point alloy powder is gently placed on the upper portion of the low-melting-point alloy powder, and jolt ramming and jolt flattening are adopted; s4, a pressing plate is pressed on the upper portion of the high-melting-point alloy powder; s5, placing the crucible in a vacuum furnace, and applying pressure on a pressing plate as required; and S6, vacuumizing, heating and sintering. The prefabricated part prepared through the method is compact in structure, the problem of poor compactness is avoided, the activity of the high-melting-point alloy powder and the activity of the low-melting-point alloy powder of the prefabricated part are kept unchanged, and the high-temperature mechanical property and the high-temperature creep resistance of the repaired position can be effectively improved.

Description

Technical Field

[0001] The present invention relates to the field of powder metallurgy applications of superalloys, especially the field of repair applications of powder metallurgy preforms of high-melting-point alloys for high-temperature hot-end components such as aviation, industrial gas turbine blades, and burners; specifically, it is a preparation method and a preform of a powder metallurgy preform for reshaping the shape and properties of damage defects of nickel-based superalloys. Background Art

[0002] High-temperature hot-end components used in industries such as aviation, industrial gas, and nuclear power work in harsh environments of high temperature, high pressure, and high stress for a long time, and are prone to problems such as wear and cracks. The powder metallurgy pre-sintering repair technology of high-melting-point alloys can be used for the repair of these components to restore their performance and extend their service life. For example, repairing the worn tip of a turbine blade can improve the aerodynamic performance and working efficiency of the blade, and reduce the maintenance cost and replacement frequency. Some structural components of an aircraft, such as landing gears and wing connectors, will also be damaged due to external force impacts during long-term use. Through pre-sintering repair, the original strength and stiffness of these structural components can be restored to ensure the flight safety of the aircraft. In a nuclear power reactor, some key components such as fuel element claddings and control rods need to work in high-temperature and irradiated environments, and have high requirements for the anti-irradiation performance, high-temperature resistance performance, and corrosion resistance performance of the materials. The powder metallurgy pre-sintering repair technology of high-melting-point alloys can provide an effective repair solution for these components, extend the service life of the nuclear reactor, and improve the safety and economy of nuclear energy utilization.

[0003] For the preparation of preforms by powder metallurgy of high-melting-point alloys, the traditional method is to first stir and mix two different powders evenly, then press them into blank blocks, and then fire them. Using the traditional method, there is a problem of poor density. The Chinese patent document discloses "a preparation method of a rare earth-doped particle-reinforced steel-based composite material" (publication number CN113909456A, publication date January 11, 2022). This technology uses pressing and negative pressure methods to solve the problem of poor density, but the preform has been completely metallurgically bonded and cannot be used for repair, or the metallurgical bonding at the welding interface of the repaired product is poor. Therefore, the various alloys in the starting blank of the alloy powder metallurgy preform are completely fused but in an unfused state. Especially for preforms of superalloys, when repairing, various alloys react again to achieve metallurgical fusion, but its preparation is extremely difficult, and no good preparation method has been found yet. Summary of the Invention

[0004] The object of the present invention is: aiming at the deficiencies of the prior art, to provide a preparation method of a powder metallurgy preform for reshaping the shape and properties of damage defects of nickel-based superalloys. This method can prepare large-sized preforms, and at the same time, the preforms prepared have a dense structure, avoiding the problem of poor density. The activity of the high-melting-point alloy and low-melting-point alloy powders in the preforms remains unchanged; during the repair of the preforms, the high / low melting-point alloy powder metallurgy is fused, improving the high-temperature mechanical properties and high-temperature creep resistance of the repaired position.

[0005] The technical object of the present invention is achieved by the following technical solutions: A preparation method of a powder metallurgy preform for reshaping the shape and properties of damage defects of nickel-based superalloys specifically includes the following steps: S1. Prepare the alloy powder for preparing the preform and the crucible for containing the alloy powder. The alloy powder includes 30%-50% low-melting-point alloy powder and 50%-70% high-melting-point alloy powder by weight percentage; S2. Put the low-melting-point alloy powder at the bottom of the crucible and compact and level it by vibration.

[0006] S3. After step S2, gently put the high-melting-point alloy powder on the upper part of the low-melting-point alloy powder and also compact and level it.

[0007] S4. After step S3, press a pressing plate on the upper part of the high-melting-point alloy powder; S5. After step S4, place the crucible in a vacuum furnace and apply pressure on the pressing plate as needed to ensure that when the low-melting-point alloy powder at the bottom of the high-melting-point alloy powder becomes liquid, the liquid level drops; the lower part of the high-melting-point alloy powder and the upper surface of the liquid of the low-melting-point alloy powder always maintain a wetting state; S6. After step S5, evacuate and heat up for sintering; among them, the heating and sintering adopt stepwise heating. When the temperature of the heating and sintering rises above the melting point of the low-melting-point alloy powder and below the melting point of the high-melting-point alloy powder; take 1 temperature point in this temperature range and keep it warm for 30 minutes; after the heat preservation is completed, cool it to room temperature with the furnace.

[0008] Preferably, in step S2, the composition of the low-melting-point alloy powder is determined according to the requirements of each component of the preform. The particle size range of the low-melting-point alloy powder is 30-50μm, and the low-melting-point alloy powder is prepared by gas atomization method; when compacting and leveling by vibration, the vibration frequency is 0.6-0.9Hz, and the vibration time is 30-60 minutes; after compaction, scrape and compact the surface layer through the pressing plate.

[0009] Preferably, in step S3, the composition of the high melting point alloy powder is determined according to the composition requirements of the preform; the melting point of the high melting point alloy powder should be at least 10°C higher than the melting point temperature of the low melting point alloy powder; the particle size range of the high melting point alloy powder is 53 - 75μm; the high melting point alloy powder is prepared by the high speed rotating electrode method; when compressing and leveling by vibration, the vibration frequency is 0.6 - 0.9Hz, and the vibration time is 30 - 60min; after compaction, the surface layer is scraped flat by a pressing plate and compacted by the pressing plate.

[0010] Preferably, in step S4, the pressing plate is made of a material with a melting point temperature higher than that of the high melting point alloy powder; there is a clearance fit between the pressing plate and the inner wall at the opening of the crucible, and the clearance is less than or equal to 2mm; when the pressing plate is arranged at the opening of the crucible, the upper surface of the pressing plate is higher than the upper surface of the crucible.

[0011] Preferably, the thickness of the pressing plate is 6 - 10mm; the upper surface of the pressing plate is 5 - 10mm higher than the upper surface of the crucible.

[0012] Preferably, in step S5, a pressure block is added to the pressing plate, and the weight of the pressure block is more than 5 times the weight of the high melting point alloy powder.

[0013] Preferably, in step S6, when evacuating; evacuate through a vacuum furnace, and after the vacuum degree reaches 6×10 -3 Pa, then power on and heat the vacuum furnace; When heating and sintering; when the temperature is below 500°C, the heating rate is 10°C / min; When the temperature rises to 500°C, keep it warm for 30min; When the temperature rises above 500°C, the lowest temperature in the temperature range is 5 - 10°C above the melting point of the low melting point alloy powder, and the highest temperature in the temperature range is 5 - 10°C below the melting point of the high melting point alloy powder, and take 1 temperature point in this temperature range to keep it warm for 30min; after the heat preservation is completed, cool it to room temperature with the furnace.

[0014] Preferably, the cross-section of the crucible is a structure with a smaller upper part and a larger lower part, and the included angle between the bottom edge and the inclined side is 85° - 88°.

[0015] A powder metallurgy preform for reshaping the damage and defects of a nickel-based superalloy is made by the above-mentioned preparation method.

[0016] Preferably, the alloy powder for preparing the preform includes 30% low melting point alloy powder and 70% high melting point alloy powder by weight percentage; The low-melting-point alloy powder, by weight percentage, contains: 12.86% - 13.86% of Cr, 24.08% - 25.08% of Co, 7.09% - 8.09% of Mo, 1.26% - 2.16% of Al, 2.08 - 3.08% of W, 0.20% - 0.30% of Si, 3.0% - 5.0% of Hf, 9.56% - 10.56% of Ti, 0.56% - 1.06% of Ta, 2.22% - 2.82% of Nb, 0.1% - 0.13% of Zr, 0.15% - 0.17% of B; the remaining part is Ni and inevitable impurity elements; The high-melting-point alloy powder, by weight percentage, contains: 14.0% - 14.6% of Cr, 8.20% - 8.80% of Co, 3.5% - 4.0% of Al, 1.2 - 1.4% of W, 0.012% - 0.017% of B, 1.0% - 1.6% of Ti, 3.5% - 4.8% of Ta, 0.05% - 0.09% of Nb, 0.10% - 0.12% of Zr; the remaining part is Ni and inevitable impurity elements.

[0017] Compared with the prior art, the beneficial effects of the present invention are: 1. Through layer-by-layer vibration compaction and pressing plate pressurization, the present invention avoids the composition segregation caused by traditional mixed powders, improves the density of the preform, and solves the problem of poor density in traditional mixed pressing. During the sintering process, a pressure of 5 times the weight of the high-melting-point powder (about 1.5 - 2 MPa) is applied to force the high-melting-point particles to embed in the liquid-phase matrix, eliminating the interfacial pores (porosity < 0.5%). By ensuring continuous contact between the low-melting-point alloy powder and the high-melting-point powder after the low-melting-point alloy powder melts through pressure, the activity of the high-melting-point alloy is retained, metallurgical fusion is achieved during repair, and the interfacial bonding strength is improved. A layered filling structure of low-melting-point (30% - 50 wt%) and high-melting-point (50% - 70 wt%) alloy powders is adopted to achieve a composite densification mechanism of "solid skeleton + liquid infiltration" through liquid-phase sintering. Through the vacuum sintering process, oxidation is prevented, and the high-temperature properties of the alloy (such as creep resistance and corrosion resistance) are guaranteed, which is suitable for harsh environments such as aviation turbine blades. Through the combination of layered powder design + dynamic pressing of the pressing plate + vacuum gradient sintering, the problems of low density of traditional powder metallurgy preforms and poor bonding of the repair interface are solved, and it is particularly suitable for the repair of high-temperature components such as aviation engine blades. Brief Description of the Drawings

[0018] Figure 1 is a schematic diagram during the preparation of the preform of the present invention; Figure 2 is a finished product diagram of the preform of the present invention; Figure 3 is a metallographic structure diagram of the preform obtained in Example 1; Figure 4 It is the metallographic structure diagram of the preform obtained in Example 2; Figure 5 It is the metallographic structure diagram of the preform obtained in Example 3; Reference numerals: 1 - crucible; 11 - pressing plate; 2 - low melting point alloy powder; 3 - high melting point alloy powder. Detailed implementation manners

[0019] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and shown in the accompanying drawings here can be arranged and designed in various different configurations.

[0020] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed present invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0021] It should be noted that: similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. In addition, the terms "first", "second", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0022] Example 1 As Figure 1 — Figure 3 shown, a preparation method of a powder metallurgy preform for reshaping damage defects of a nickel-based superalloy specifically includes the following steps: S1. Prepare the alloy powder for preparing the preform and the crucible 1 for containing the alloy powder. The alloy powder includes 30%-50% of low melting point alloy powder 2 and 50%-70% of high melting point alloy powder 3 by weight percentage; S2. Put the low melting point alloy powder 2 at the bottom of the crucible 1 and compact and level it by vibration.

[0023] S3. After step S2, gently put the high melting point alloy powder 3 on the upper part of the low melting point alloy powder 2 and also compact and level it.

[0024] S4. After step S3, press the pressing plate 11 on the upper part of the high melting point alloy powder 3; S5. After step S4, place the crucible 1 in a vacuum furnace and apply pressure on the pressing plate 11 as required to ensure that the liquid level drops after the low-melting-point alloy powder 2 at the bottom of the high-melting-point alloy powder 3 becomes liquid; the lower part of the high-melting-point alloy powder 3 and the upper surface of the liquid level of the low-melting-point alloy powder 2 always maintain a wetting state. S6. After step S5, evacuate the air and raise the temperature for sintering; among them, the temperature increase for sintering adopts a stepped temperature increase. When the temperature for temperature increase and sintering rises above the melting point of the low-melting-point alloy powder 2 and below the melting point of the high-melting-point alloy powder 3; take 1 temperature point in this temperature range and keep it warm for 30 minutes; after the heat preservation is completed, cool it to room temperature with the furnace.

[0025] Through layered vibration compaction + pressing by the pressing plate 11: Avoid the composition segregation caused by traditional mixed powders, improve the density of the preform, and solve the problem of poor density in traditional mixed pressing. Apply a pressure of 5 times the weight of the high-melting-point powder (about 1.5 - 2 MPa) during the sintering process to force the high-melting-point particles to embed in the liquid-phase matrix and eliminate the interfacial pores (porosity < 0.5%). Ensure that the low-melting-point alloy powder 2 remains in continuous contact with the high-melting-point powder after melting through pressure, retain the activity of the high-melting-point alloy, achieve metallurgical fusion during repair, and improve the interfacial bonding strength. Adopt a layered filling structure of low-melting-point (30% - 50 wt%) and high-melting-point (50% - 70 wt%) alloy powders, and realize the composite densification mechanism of "solid skeleton + liquid infiltration" through liquid-phase sintering. Through the vacuum sintering process, prevent oxidation and ensure the high-temperature performance of the alloy (such as creep resistance, corrosion resistance), which is suitable for harsh environments such as aviation turbine blades. Through the combination of layered powder design + dynamic pressing by the pressing plate 11 + vacuum gradient sintering, the problems of low density of traditional powder metallurgy preforms and poor bonding of repair interfaces are solved, and it is especially suitable for the repair of high-temperature components such as aviation engine blades.

[0026] During specific implementation, the cross-section of the crucible 1 is a structure with a smaller upper part and a larger lower part, and the included angle between the bottom edge and the inclined side is 85° - 88°. Adopting this technical measure has the advantages of optimized powder filling and convenient demolding. Specifically, the conical structure (slant angle 2° - 5°) reduces the frictional resistance of the powder on the side wall during vibration compaction and improves the filling uniformity (radial density deviation ≤ 1%). After sintering, the preform naturally separates from the crucible due to shrinkage (demolding force ≤ 10 kN), avoiding mechanical damage.

[0027] The pressing plate 11 is made of a material with a melting point temperature higher than the melting point temperature of the high-melting-point alloy powder 3; there is a clearance fit between the pressing plate 11 and the inner wall at the opening of the crucible 1, and the clearance is less than or equal to 2 mm; when the pressing plate 11 is arranged at the opening of the crucible 1, the upper surface of the pressing plate 11 is higher than the upper surface of the crucible 1.

[0028] The components of the low-melting-point alloy powder 2 and the high-melting-point alloy powder 3 in step S1 are determined according to the requirements of each component of the preform; in this embodiment, the alloy powder used in the preform includes 30% low-melting-point alloy powder 2 and 70% high-melting-point alloy powder 3 by weight percentage.

[0029] Step S2: Place the low-melting-point alloy powder 2 at the bottom of the crucible 1 and compact and level it by vibration.

[0030] The low-melting-point alloy powder 2, by weight percentage, contains: 12.86% - 13.86% of Cr, 24.08% - 25.08% of Co, 7.09% - 8.09% of Mo, 1.26% - 2.16% of Al, 2.08 - 3.08% of W, 0.20% - 0.30% of Si, 3.0% - 5.0% of Hf, 9.56% - 10.56% of Ti, 0.56% - 1.06% of Ta, 2.22% - 2.82% of Nb, 0.1% - 0.13% of Zr, 0.15% - 0.17% of B; the rest is Ni and inevitable impurity elements. The melting point temperature of this low-melting-point alloy powder 2 is 1130 - 1160 °C, and the powder particle size is 30 - 50 μm. The particle size of this low-melting-point alloy powder 2 is prepared by gas atomization method; when compacting and leveling by vibration, the vibration frequency is 0.6 - 0.9 Hz, and the vibration time is 30 - 60 min; in specific implementation, place the crucible 1 filled with the low-melting-point alloy powder 2 on the compaction table, control the frequency of the compaction table to be 0.9 Hz, and the compaction time to be 30 min. After compaction, scrape and compact the surface layer through the pressing plate 11. By adopting this technical measure, the 30 - 50 μm powder has good fluidity, and the porosity after compaction is reduced to less than 5%, thereby improving the density after sintering. The spherical powder obtained by gas atomization method has a packing density increased by 15% - 20%, reducing the sintering shrinkage deformation. During vibration, the 0.6 - 0.9 Hz low-frequency vibration avoids powder splashing, and the 30 - 60 min compaction time ensures uniform density.

[0031] Step S3: Gently place the high-melting-point alloy powder 3 on top of the low-melting-point alloy powder 2 and also compact and level it.

[0032] The high melting point alloy powder 3 contains, by weight percentage: 4.5% - 5.5% of Cr, 10.07% - 10.80% of Co, 3.1% - 4.0% of Al, 9.5 - 10.6% of W, 0.012% - 0.017% of B, 0.5% - 1.0% of Ti, 0.01% - 0.12% of Zr; the remaining part is Ni and inevitable impurity elements. The melting point of the high melting point alloy powder 3 needs to be at least 10°C higher than the melting point temperature of the low melting point alloy powder 2; the melting point temperature of this high melting point alloy powder 3 is 1350 - 1400°C, and the powder particle size is 53 - 75μm. The high melting point alloy powder 3 is prepared by the high-speed rotating electrode method; when using the vibration method for compaction and leveling, the vibration frequency is 0.6 - 0.9Hz, and the vibration time is 30 - 60min; in specific implementation, according to step S3, the high melting point alloy powder 3 is placed on the upper part of the low melting point alloy powder 2 in the crucible 1, the crucible 1 is placed on the compaction table, the frequency of the compaction table is controlled at 0.9, and the compaction time is 60min. After compaction, it is hand-scraped and compacted. By adopting this technical measure, using 53 - 75μm high melting point powder to form a particle size gradient with the low melting point layer, the liquid metal is more likely to penetrate during sintering, and the interfacial bonding strength is increased by 20%. The powder oxygen content prepared by the high-speed rotating electrode method is <100ppm, reducing the influence of impurities on the high-temperature performance. The melting point difference ≥10°C: ensuring that only the low melting point melts during sintering, and the high melting point remains as a solid skeleton to prevent component mixing.

[0033] Step S4: Press the pressing plate 11 on the upper part of the high melting point alloy powder 3. Specifically, place the pressing plate 11 on the upper part of the compacted high melting point alloy powder 3. The thickness of the pressing plate 11 is 6 - 10mm; the gap between the pressing plate 11 and the inner wall at the opening of the crucible 1 is less than or equal to 2mm. Place the pressing plate 11 horizontally on the upper part of the high melting point alloy powder 3, and the upper surface of the pressing plate 11 is 5 - 10mm higher than the upper surface of the crucible 1. Among them, the ≤2mm gap prevents powder leakage and at the same time allows thermal expansion deformation to avoid jamming of the pressing plate 11. The thickness of the pressing plate 11 is 6 - 10mm, ensuring rigidity, and the uniformity error of pressure transmission is <3%. The upper surface of the pressing plate 11 is 5 - 10mm higher than the upper surface of the crucible 1, providing a mounting space for the pressure block and adapting to crucibles of different sizes.

[0034] Step S5: Place the crucible 1 in the vacuum furnace, and apply pressure on the pressing plate 11 as needed to ensure that the liquid level drops after the low melting point alloy powder 2 at the bottom of the high melting point alloy powder 3 becomes liquid; the lower part of the high melting point alloy powder 3 and the upper surface of the liquid of the low melting point alloy powder 2 always maintain a wetting state.

[0035] Specifically, place the well-compacted crucible 1 in a vacuum furnace, apply pressure on the pressing plate 11 as needed, add pressure blocks (not shown in the figure) on the pressing plate 11, and the weight of the pressure blocks is more than 5 times the weight of the high-melting-point alloy powder 3; after the pressure blocks are pressed on the pressing plate 11, the pressing plate 11 pushes the high-melting-point alloy powder 3 to move downward. The 5-fold weight provides a pressure of about 0.5 - 1 MPa, which pushes the high-melting-point powder downward to compensate for liquid shrinkage, and the porosity is reduced to less than 2%. The lower part of the high-melting-point alloy powder 3 and the upper surface of the liquid surface of the low-melting-point alloy powder 2 always maintain a wetting state. Keep the high-melting-point powder in contact with the liquid alloy, and the interfacial wetting angle < 30°, and the metallurgical bonding area is increased to more than 95%.

[0036] Step S6: Evacuate the vacuum and raise the temperature for sintering; raise the temperature for sintering to above the melting point of the low-melting-point alloy powder 2 and below the melting point of the high-melting-point alloy powder 3; keep it warm in this temperature range, and after the heat preservation is completed, cool it to room temperature with the furnace.

[0037] The vacuum furnace evacuates the vacuum to prevent the alloy powder from oxidizing. In this embodiment, when evacuating the vacuum; evacuate the vacuum through the vacuum furnace, and after the vacuum degree reaches 6×10 -3 Pa, then supply power to heat the vacuum furnace; When raising the temperature for sintering; when the temperature is below 500°C, the heating rate is 10°C / min; When the temperature rises to 500°C, keep it warm for 30 min; When the temperature rises above 500°C, the lowest temperature in the temperature range is 5 - 10°C above the melting point of the low-melting-point alloy powder 2, and the highest temperature in the temperature range is 5 - 10°C below the melting point of the high-melting-point alloy powder 3, and take 1 temperature point in this temperature range to keep it warm for 30 min; after the heat preservation is completed, cool it to room temperature with the furnace.

[0038] When using stepwise heating, keep it warm at 500°C to remove adsorbed gas and reduce pores; keep it warm for 30 min in the melting point range to ensure sufficient diffusion of the liquid phase, and control the grain size within 20 - 50 μm.

[0039] In specific implementation, according to the melting points of the low-melting-point alloy powder 2 and the high-melting-point alloy powder 3 in this embodiment, when the temperature rises above 500°C, take 1 temperature point in the temperature range of 1170°C - 1340°C to keep it warm for 30 min. After the heat preservation is completed, cool it to room temperature with the furnace. That is, a preform of the superalloy is obtained.

[0040] The obtained preform is as Figure 2 shown, and the metallographic structure of this preform is as Figure 3 shown.

[0041] Example 2 As Figure 1 、 Figure 4As shown, other contents of this embodiment are the same as those of Embodiment 1, and the differences are as follows: The components of the low-melting-point alloy powder 2 and the high-melting-point alloy powder 3 in step S1 are determined according to the requirements of each component of the preform; in this embodiment, the alloy powder used in the preform includes 30% of the low-melting-point alloy powder 2 and 70% of the high-melting-point alloy powder 3 by weight percentage.

[0042] Step S2: Place the low-melting-point alloy powder 2 at the bottom of the crucible 1, and compact and level it by vibration.

[0043] The low-melting-point alloy powder 2, by weight percentage, contains: 12.86% - 13.86% of Cr, 24.08% - 25.08% of Co, 7.09% - 8.09% of Mo, 1.26% - 2.16% of Al, 2.08 - 3.08% of W, 0.20% - 0.30% of Si, 3.0% - 5.0% of Hf, 9.56% - 10.56% of Ti, 0.56% - 1.06% of Ta, 2.22% - 2.82% of Nb, 0.1% - 0.13% of Zr, 0.15% - 0.17% of B; the rest is Ni and inevitable impurity elements.

[0044] The melting point temperature of the low-melting-point alloy powder 2 is 1130 - 1160 °C, and the powder particle size is 30 - 50 μm. The particle size of the low-melting-point alloy powder 2 is prepared by gas atomization method; when compacting and leveling by vibration, the vibration frequency is 0.6 - 0.9 Hz, and the vibration time is 30 - 60 min; in specific implementation, place the crucible 1 filled with the low-melting-point alloy powder 2 on the compaction table, control the frequency of the compaction table at 0.9 Hz, and the compaction time at 30 min. After compaction, scrape and level the surface layer through the pressing plate 11, and compact the surface layer through the pressing plate 11.

[0045] Step S3: Gently place the high-melting-point alloy powder 3 on the upper part of the low-melting-point alloy powder 2, and also compact and level it.

[0046] The high-melting-point alloy powder 3, by weight percentage, contains: 14.0% - 14.6% of Cr, 8.20% - 8.80% of Co, 3.5% - 4.0% of Al, 1.2 - 1.4% of W, 0.012% - 0.017% of B, 1.0% - 1.6% of Ti, 3.5% - 4.8% of Ta, 0.05% - 0.09% of Nb, 0.10% - 0.12% of Zr; the rest is Ni and inevitable impurity elements. The melting point of the high-melting-point alloy powder 3 needs to be at least 10 °C higher than the melting point temperature of the low-melting-point alloy powder 2; the melting point temperature of the high-melting-point alloy powder 3 is 1330 - 1380 °C, and the powder particle size is 53 - 75 μm.

[0047] The high melting point alloy powder 3 is prepared by the high-speed rotating electrode method; when compacting and leveling by vibration, the vibration frequency is 0.6 - 0.9 Hz, and the vibration time is 30 - 60 min; in specific implementation, according to step S3, the high melting point alloy powder 3 is placed on the upper part of the low melting point alloy powder 2 in the crucible 1, the crucible 1 is placed on the compaction table, the frequency of the compaction table is controlled at 0.9, the compaction time is 60 min, and after compaction, it is manually leveled and compacted.

[0048] Step S4: Press the pressing plate 11 on the upper part of the high melting point alloy powder 3. Specifically, the pressing plate 11 is placed on the upper part of the compacted high melting point alloy powder 3, and the thickness of the pressing plate 11 is 6 - 10 mm; the gap between the pressing plate 11 and the inner wall at the opening of the crucible 1 is less than or equal to 2 mm. The pressing plate 11 is horizontally placed on the upper part of the high melting point alloy powder 3, and the upper surface of the pressing plate 11 is 5 - 10 mm higher than the upper surface of the crucible 1.

[0049] After step S5, the crucible 1 is placed in the vacuum furnace, and pressure is applied on the pressing plate 11 as needed to ensure that the liquid level drops after the low melting point alloy powder 2 at the bottom of the high melting point alloy powder 3 becomes liquid; the lower part of the high melting point alloy powder 3 and the upper surface of the liquid of the low melting point alloy powder 2 always maintain a wetting state.

[0050] Step S6: Evacuate the air and raise the temperature for sintering; the temperature for raising the temperature and sintering is raised above the melting point of the low melting point alloy powder 2 and below the melting point of the high melting point alloy powder 3; keep it warm in this temperature range, and after the heat preservation is completed, cool it to room temperature with the furnace.

[0051] The vacuum furnace evacuates the air to prevent the alloy powder from oxidizing. In this embodiment, when evacuating the air; evacuate the air through the vacuum furnace, and after the vacuum degree reaches 6×10 -3 Pa, then supply power to heat the vacuum furnace; When raising the temperature and sintering; when the temperature is below 500 °C, the heating rate is 10 °C / min; When the temperature rises to 500 °C, keep it warm for 30 min; When the temperature rises above 500 °C, the lowest temperature in the temperature range is 5 - 10 °C above the melting point of the low melting point alloy powder 2, the highest temperature in the temperature range is 5 - 10 °C below the melting point of the high melting point alloy powder 3, and take 1 temperature point in this temperature range to keep it warm for 30 min; after the heat preservation is completed, cool it to room temperature with the furnace.

[0052] In specific implementation, according to the melting points of the low melting point alloy powder 2 and the high melting point alloy powder 3 in this embodiment, when the temperature rises above 500 °C, take 1 temperature point in the temperature range of 1170 °C - 1320 °C to keep it warm for 30 min, and after the heat preservation is completed, cool it to room temperature with the furnace. That is, the preform of the superalloy is obtained.

[0053] The metallographic structure of the obtained preform is as Figure 4As shown, the internal structure is uniform and delicate, avoiding the problem of poor density, and providing a high-strength, high-temperature-resistant preform matrix for the repair of superalloy damage.

[0054] Example 3 As Figure 1 , Figure 5 shown, other contents of this example are the same as those of Example 1, except that: The components of the low-melting-point alloy powder 2 and the high-melting-point alloy powder 3 in step S1 are determined according to the requirements of each component of the preform; in this example, the alloy powder used in the preform includes 50% low-melting-point alloy powder 2 and 50% high-melting-point alloy powder 3 by weight percentage.

[0055] Step S2: Put the low-melting-point alloy powder 2 at the bottom of the crucible 1 and compact and level it by vibration.

[0056] The low-melting-point alloy powder 2, by weight percentage, contains: 13.3%-14.3% of Cr, 9.0%-10.0% of Co, 5.3%-6.3% of Al, <0.01% of W, 0.07%-0.13% of Zr, 5.4%-6.4% of Ti, 4.2%-5.0% of Ta, 10.0%-10.8% of Mo, 1.55%-2.25% of Nb, 0.015%-0.025% of B, 0.45%-0.95% of Si; the rest is Ni and inevitable impurity elements. The melting point temperature of this low-melting-point alloy powder 2 is 1150-1160°C, and the powder particle size is 30-50μm. The particle size of this low-melting-point alloy powder 2 is prepared by gas atomization method; when compacting and leveling by vibration, the vibration frequency is 0.6-0.9Hz, and the vibration time is 30-60min; in specific implementation, the crucible 1 filled with the low-melting-point alloy powder 2 is placed on the compaction table, and the frequency of the compaction table is controlled at 0.9Hz, and the compaction time is 30min. After compaction, the surface layer is scraped flat by the pressing plate 11 and compacted by the pressing plate 11.

[0057] Step S3: Gently put the high-melting-point alloy powder 3 on the upper part of the low-melting-point alloy powder 2 and also compact and level it.

[0058] The high melting point alloy powder 3, by weight percentage, contains: 14.0% - 14.6% of Cr, 8.20% - 8.80% of Co, 3.5% - 4.0% of Al, 1.2 - 1.4% of W, 0.012% - 0.017% of B, 1.0% - 1.6% of Ti, 3.5% - 4.8% of Ta, 0.05% - 0.09% of Nb, 0.10% - 0.12% of Zr; the rest is Ni and inevitable impurity elements. The melting point of the high melting point alloy powder 3 needs to be at least 10 °C higher than the melting point temperature of the low melting point alloy powder 2; the melting point temperature of this high melting point alloy powder 3 is 1330 - 1380 °C, and the powder particle size is 53 - 75 μm. The high melting point alloy powder 3 is prepared by the high-speed rotating electrode method; when compacting and leveling by vibration, the vibration frequency is 0.6 - 0.9 Hz, and the vibration time is 30 - 60 min; in specific implementation, according to step S3, the high melting point alloy powder 3 is placed on the upper part of the low melting point alloy powder 2 in the crucible 1, the crucible 1 is placed on the compaction table, the frequency of the compaction table is controlled at 0.9, and the compaction time is 60 min. After compaction, it is hand-scraped and compacted.

[0059] Step S4: Press the pressing plate 11 on the upper part of the high melting point alloy powder 3. Specifically, the pressing plate 11 is placed on the upper part of the compacted high melting point alloy powder 3, and the thickness of the pressing plate 11 is 6 - 10 mm; the gap between the pressing plate 11 and the inner wall at the opening of the crucible 1 is less than or equal to 2 mm. The pressing plate 11 is horizontally placed on the upper part of the high melting point alloy powder 3, and the upper surface of the pressing plate 11 is 5 - 10 mm higher than the upper surface of the crucible 1.

[0060] Step S5: Place the crucible 1 in the vacuum furnace, and apply pressure on the pressing plate 11 as needed to ensure that the liquid level drops after the low melting point alloy powder 2 at the bottom of the high melting point alloy powder 3 becomes liquid; the lower part of the high melting point alloy powder 3 and the upper surface of the liquid level of the low melting point alloy powder 2 always maintain a wetting state.

[0061] Step S6: Evacuate the air and raise the temperature for sintering; the temperature for raising the temperature and sintering rises above the melting point of the low melting point alloy powder 2 and below the melting point of the high melting point alloy powder 3; keep it warm in this temperature range, and after the heat preservation is completed, cool it to room temperature with the furnace.

[0062] The vacuum furnace evacuates the air to prevent the alloy powder from oxidizing. In this embodiment, when evacuating the air; evacuate the air through the vacuum furnace, and after the vacuum degree reaches 6×10 -3 Pa, then supply power to heat the vacuum furnace; When raising the temperature for sintering; when the temperature is below 500 °C, the heating rate is 10 °C / min; When the temperature rises to 500 °C, keep it warm for 30 min; After the temperature rises above 500°C, the lowest temperature in the temperature range is 5 - 10°C above the melting point of the low-melting-point alloy powder 2, and the highest temperature in the temperature range is 5 - 10°C below the melting point of the high-melting-point alloy powder 3. Then, take one temperature point in this temperature range and keep it warm for 30 minutes. After the heat preservation is completed, cool it in the furnace to room temperature.

[0063] In specific implementation, according to the melting points of the low-melting-point alloy powder 2 and the high-melting-point alloy powder 3 in this embodiment, after the temperature rises above 500°C, take one temperature point in the temperature range of 1170°C - 1320°C and keep it warm for 30 minutes. After the heat preservation is completed, cool it in the furnace to room temperature. Thus, the preform of the superalloy is obtained.

[0064] The metallographic structure of the obtained preform is as Figure 5 shown.

[0065] The technical solutions provided by the embodiments of the present invention have been introduced in detail above. Specific examples are used in this article to elaborate on the principles and implementation manners of the embodiments of the present invention. The descriptions of the above embodiments are only applicable to help understand the principles of the embodiments of the present invention. At the same time, for those of ordinary skill in the art, based on the embodiments of the present invention, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A preparation method of a powder metallurgy preform for reshaping the shape and properties of damage defects of a nickel-based superalloy, characterized in that, Specifically, it includes the following steps: S1. Prepare alloy powder for preparing the preform and a crucible for containing the alloy powder. The alloy powder includes 30%-50% low-melting-point alloy powder and 50%-70% high-melting-point alloy powder by weight percentage; S2. Put the low-melting-point alloy powder at the bottom of the crucible and compact and level it by vibration; S3. After step S2, gently put the high-melting-point alloy powder on the upper part of the low-melting-point alloy powder and also compact and level it; S4. After step S3, press a pressing plate on the upper part of the high-melting-point alloy powder; S5. After step S4, place the crucible in a vacuum furnace and apply pressure on the pressing plate as needed to ensure that when the low-melting-point alloy powder at the bottom of the high-melting-point alloy powder becomes liquid, the liquid level drops; the lower part of the high-melting-point alloy powder and the upper surface of the liquid of the low-melting-point alloy powder always maintain a wetting state; S6. After step S5, evacuate and sinter by heating; Among them, the sintering by heating uses stepwise heating. When the temperature of the sintering by heating rises above the melting point of the low-melting-point alloy powder and below the melting point of the high-melting-point alloy powder; take 1 temperature point in this temperature range and keep it warm for 30 min; after the heat preservation is completed, cool it to room temperature with the furnace; 2. The preparation method of the powder metallurgy preform for reshaping the damage defects of the nickel-based superalloy according to claim 1, characterized in that, In step S2, the composition of the low-melting-point alloy powder is determined according to the requirements of each component of the preform. The particle size range of the low-melting-point alloy powder is 30-50 μm. The low-melting-point alloy powder is prepared by gas atomization method; when compacting and leveling by vibration, the vibration frequency is 0.6-0.9 Hz and the vibration time is 30-60 min; after compacting, scrape and compact the surface layer through the pressing plate.

3. The preparation method of the powder metallurgy preform for reshaping the damage defects of the nickel-based superalloy according to claim 1, wherein, In step S3, the composition of the high-melting-point alloy powder is determined according to the composition requirements of the preform; the melting point of the high-melting-point alloy powder needs to be at least 10 °C higher than the melting point temperature of the low-melting-point alloy powder; the particle size range of the high-melting-point alloy powder is 53-75 μm; the high-melting-point alloy powder is prepared by high-speed rotating electrode method; when compacting and leveling by vibration, the vibration frequency is 0.6-0.9 Hz and the vibration time is 30-60 min; after compacting, scrape and compact the surface layer through the pressing plate.

4. The preparation method of the powder metallurgy preform for reshaping the damage defects of the nickel-based superalloy according to claim 1, characterized in that, In step S4, the pressing plate is made of a material with a melting point temperature higher than the melting point temperature of the high-melting-point alloy powder; there is a clearance fit between the pressing plate and the inner wall at the opening of the crucible, and the clearance is less than or equal to 2 mm; when the pressing plate is set at the opening of the crucible, the upper surface of the pressing plate is higher than the upper surface of the crucible.

5. The preparation method of the powder metallurgy preform for reshaping the damage defects of the nickel-based superalloy according to claim 4, characterized in that, The thickness of the pressing plate is 6-10 mm; the upper surface of the pressing plate is 5-10 mm higher than the upper surface of the crucible.

6. The preparation method of the powder metallurgy preform for reshaping the damage defects of the nickel-based superalloy according to claim 1, characterized in that, In step S5, a pressure block is added to the pressing plate, and the weight of the pressure block is more than 5 times the weight of the high-melting-point alloy powder.

7. The preparation method of the powder metallurgy preform for reshaping the damage defects of the nickel-based superalloy according to claim 1, characterized in that, In step S6, When evacuating, evacuate through a vacuum furnace. After the vacuum degree reaches 6×10 -3 Pa, then supply power to the vacuum furnace for heating; When sintering by heating; when the temperature is below 500 °C, the heating rate is 10 °C / min; When the temperature rises to 500 °C, keep it warm for 30 min; When the temperature rises above 500 °C, the lowest temperature in the temperature range is 5 - 10 °C above the melting point of the low-melting-point alloy powder, and the highest temperature in the temperature range is 5 - 10 °C below the melting point of the high-melting-point alloy powder. One temperature point is selected in this temperature range for heat preservation for 30 min; after heat preservation, it is cooled to room temperature with the furnace.

8. The preparation method of the powder metallurgy preform for reshaping the damage defects of the nickel-based superalloy according to claim 1, wherein, The cross-section of the crucible has a structure with a smaller upper part and a larger lower part, and the angle between the bottom edge and the inclined side is 85° - 88°.

9. A powder metallurgy preform for reshaping the shape and properties of damage defects in a nickel-based superalloy, characterized in that, It is made by the preparation method described in any one of claims 1 to 8.

10. The powder metallurgy preform for reshaping the damage defects of the nickel-based superalloy according to claim 9, characterized in that, The alloy powder for preparing the preform includes 30% low-melting-point alloy powder and 70% high-melting-point alloy powder by weight percentage; The low-melting-point alloy powder, by weight percentage, contains: 12.86% - 13.86% of Cr, 24.08% - 25.08% of Co, 7.09% - 8.09% of Mo, 1.26% - 2.16% of Al, 2.08 - 3.08% of W, 0.20% - 0.30% of Si, 3.0% - 5.0% of Hf, 9.56% - 10.56% of Ti, 0.56% - 1.06% of Ta, 2.22% - 2.82% of Nb, 0.1% - 0.13% of Zr, 0.15% - 0.17% of B; the remaining part is Ni and inevitable impurity elements; The high-melting-point alloy powder, by weight percentage, contains: 14.0% - 14.6% of Cr, 8.20% - 8.80% of Co, 3.5% - 4.0% of Al, 1.2 - 1.4% of W, 0.012% - 0.017% of B, 1.0% - 1.6% of Ti, 3.5% - 4.8% of Ta, 0.05% - 0.09% of Nb, 0.10% - 0.12% of Zr; the remaining part is Ni and inevitable impurity elements.

Images