A method of forming a high-alloyed superalloy powder common to multiple processes

Abstract

This invention provides a method for forming and preparing high-alloyed high-temperature alloy powder that can be used in multiple processes. To address the problems of traditional high-alloyed high-temperature alloys having limited applications, high R&D costs, and incompatibility between different processes and materials when applied in multiple fields, this method carefully balances alloying elements and controls matching forming process parameters. This improves the adaptability of the alloy to various forming processes while maintaining good mechanical properties. The alloy powder can be simultaneously used for wide-gap brazing support materials, hot isostatic pressing, and additive manufacturing. Characterization is performed using a combination of various testing and characterization methods, and the results are comparable across different processes. The results show that the alloy prepared by the forming method provided in this application has uniform and fine dendrites and grains, low porosity, good thermal stability, and possesses high mechanical properties and good forming process performance.

Description

Technical Field

[0001] This invention relates to the field of high-temperature alloy preparation technology, and in particular to a method for forming and preparing high-alloyed high-temperature alloy powder using multiple processes. Background Technology

[0002] High-temperature alloys are structural materials capable of long-term service under high temperatures above 600℃ and complex stress environments. They possess excellent high-temperature strength and environmental resistance, good fatigue resistance, and fracture toughness. Classified by composition, they can be divided into nickel-, iron-, and cobalt-based high-temperature alloys; by manufacturing process, they can be divided into wrought, cast, and powder alloys; and by strengthening mechanism, they can be divided into solid solution-strengthened and precipitation-strengthened (high-alloyed) high-temperature alloys. High-temperature alloys are widely used in the manufacture of hot-section components of aero-engines, often referred to as the "heart of gas turbines." High-temperature alloys are expensive, and a single alloy is typically developed for a single purpose, with subsequent product development costs accounting for a large proportion of the overall cost. Currently, numerous high-temperature alloy grades are under development, but the actual application of many of these grades is relatively limited. Developing high-performance high-temperature alloys suitable for multiple manufacturing processes and applications, achieving "one material for multiple uses," is of great significance for improving the application level of high-temperature alloys and reducing costs.

[0003] High-temperature alloy powders, due to their low segregation tendency and flexible volumetric forming capabilities, are used in various manufacturing processes to repair or produce structural and functional components of gas turbines. These processes include, but are not limited to, additive manufacturing, hot isostatic pressing, and wide-gap brazing. In recent years, the concept of "one material for multiple uses" has received widespread attention in materials research and manufacturing, referring to a single material with multiple applications, such as wide-gap brazing repair of component defects, hot isostatic pressing of turbine disks, and additive manufacturing of integral turbine impellers. Different alloys are typically used to meet the specific service requirements of different processes. High-temperature alloys account for over 60% of applications in engine hot-end components, requiring good high-temperature strength, comprehensive mechanical properties, and environmental resistance. Currently, China has begun to focus on the "one material for multiple uses" approach, but this mainly concentrates on nickel-based or iron-nickel-based wrought high-temperature alloys with low alloying degrees, such as GH4169. Reports on the multi-use of high-temperature alloys with high alloying degrees (with γ'-Ni3Al as the main strengthening phase) are rare, and related powder materials are even less reported. For highly alloyed high-temperature alloys, the tendency for thermal cracking during 3D printing is significantly higher than that of alloys with a lower degree of alloying. Therefore, it is crucial to develop highly alloyed high-temperature alloys that can be used in multiple processes, taking into account the characteristics of different processes (such as brazing repair and hot isostatic pressing). Summary of the Invention

[0004] The technical problem solved by this invention is to provide a forming and preparation method for high-alloyed high-temperature alloy powder used in multiple processes. The forming and preparation method provided by this application can be applied to wide-gap brazing, hot isostatic pressing and solidification forming processes and laser additive manufacturing processes. The alloy prepared by this forming and preparation method has uniform and fine dendrites and grains, low porosity, good thermal stability, and high mechanical properties and good forming process performance.

[0005] In view of this, this application provides a method for forming and preparing high-alloyed high-temperature alloy powder using multiple processes, comprising the following steps:

[0006] Based on the microstructure of powder or bulk materials prepared by different processes using high-temperature alloy powder, the characteristic temperature range of microstructure transformation in different processes is determined.

[0007] Depending on the different processes used to process the high-temperature alloy powder, the powder is sieved into different particle size ranges, and then shaped according to the temperature range.

[0008] The composition of the high-temperature alloy powder, by mass percentage, is (12-14)Cr-(19-21)Co-(3-5)W-(3-5)Mo-(2-3)Ta-(3-4)Al-(2-4)Ti-(0.02-0.03)B-(0.04-0.06)Zr-(0.5-1.5)Nb-(0.001-0.02)C-the remainder Ni;

[0009] The different processes include wide-gap brazing, hot isostatic pressing, or laser additive manufacturing.

[0010] Preferably, the holding temperature for wide-gap brazing is a temperature range below the solidus line of the powder and below the critical temperature at which dendrites transform into equiaxed crystals.

[0011] The characteristic temperature at which gas escapes from the powder surface is taken as the powder degassing and heat preservation temperature, and the temperature range between the critical temperature of dendrite transformation to equiaxed crystal and the solidus temperature is taken as the hot isostatic pressing temperature of the hot isostatic pressing solidification forming process.

[0012] The temperature range of the molten pool in laser additive manufacturing is defined as the temperature above the liquidus temperature, and the temperature range of the solid-liquid two-phase region is defined as the temperature range of the heat-affected zone in laser additive manufacturing.

[0013] Preferably, the method for preparing the high-temperature alloy powder includes the following steps:

[0014] Step 1: Prepare the raw materials for the master alloy ingot according to the elemental ratio of the high-temperature alloy powder;

[0015] Step 2: Prepare the master alloy ingot by vacuum induction melting, wherein the vacuum pressure of the vacuum induction melting is <1 Pa;

[0016] Step 3: Remelt the master alloy ingot at a temperature of 1500~1600℃, a refining temperature of 1550~1600℃, and a casting temperature of 1450~1550℃. Then, prepare high-temperature alloy powder through a gas atomization powder making furnace with a capacity of 50~300kg and an atomization pressure of 2.5~5.5MPa.

[0017] Step 4: Sieve the prepared alloy powder to a particle size of <200μm.

[0018] Preferably, the particle size of the high-temperature alloy powder in the wide-gap brazing process is 75~150μm, the particle size of the high-temperature alloy powder in the hot isostatic pressing consolidation forming process is 0~63μm, and the particle size of the high-temperature alloy powder in the laser additive manufacturing process is 53~150μm.

[0019] Preferably, the high-temperature alloy powder used in wide-gap brazing process involves filling the gap to be brazed with the high-temperature alloy powder as a gap support material. The specific process is as follows:

[0020] High-temperature alloy powder was sieved to a particle size range of 75~150μm and filled into the gap space to be repaired as a support material. It was mixed with low-melting-point brazing filler with a particle size of <20μm, heated to 1100℃ for preheating, held for 2 hours, then heated to 1150℃ for 4 hours, and cooled to room temperature. The low-melting-point brazing filler completely melted, while the high-temperature alloy powder remained solid and no obvious internal microstructure transformation occurred.

[0021] Preferably, the high-temperature alloy powder is used in a hot isostatic pressing (HIP) solidification forming process, specifically:

[0022] High-temperature alloy powder was sieved into particle size ranges of 0~63μm, then compacted, degassed, and sealed in a stainless steel sheath. The compaction time was >20s, the frequency was 60Hz, and the vacuum pressure was below 10. -3 Under the condition of Pa, high-temperature vacuum degassing is performed at a temperature of 120~180℃ / 1~3h + 250~350℃ / 1~3h + 550~600℃ / 1~3h, and the total degassing time is >5h. The stainless steel cladding is then placed in a hot isostatic press and solidified by hot isostatic pressing at a temperature of 1155~1200℃, a pressure of 150~200MPa, and a time of >3h.

[0023] Preferably, the high-temperature alloy powder used in the laser additive manufacturing process involves rapidly melting and solidifying the high-temperature alloy powder, specifically:

[0024] High-temperature alloy powder is sieved to a particle size range of 53~150μm, and then placed into a laser additive manufacturing equipment for shaping. The laser power is 700~1000w and the scanning speed is 800~1000mm / s.

[0025] Preferably, the forming process further includes heat treatment, with the solution heat treatment temperature being within 50°C above or below the average precipitation and dissolution temperature of the main reinforcing phase. Specifically, the heat treatment regime includes: 1115~1135°C / 1~4h oil cooling + 800~850°C / 16~20h air cooling or oil cooling, or 1155~1195°C / 1~4h oil cooling + 800~850°C / 16~20h air cooling or oil cooling.

[0026] Preferably, the forming preparation method further includes characterization and mechanical property testing of the high-temperature alloy powder and the formed product, wherein the characterization specifically includes:

[0027] The trace precipitates of high-temperature alloy powder, including γ' strengthening phase and carbide phase, were rapidly characterized by synchrotron X-ray diffraction. The energy of the synchrotron X-ray was 70~80 keV, the wavelength λ was 0.163137 Å, the X-ray spot size was 100~200 μm, and the exposure time was 1~2 s. The diffraction ring pattern of the alloy powder was obtained.

[0028] The bulk materials formed by powder molding were characterized by XRD. The bulk materials included wide-gap brazed support powder regions, hot isostatically pressed alloys, and high-temperature alloys manufactured by laser additive manufacturing.

[0029] By comparing the XRD curves of high-temperature alloy powder and bulk materials, we can understand the precipitation law and microstructure inheritance characteristics of precipitated phases from powder to bulk materials.

[0030] The mechanical property test specifically involves using nano-hardness testing to test the hardness of high-temperature alloy powder and bulk materials.

[0031] This application provides a method for forming and preparing high-alloyed high-temperature alloy powder using multiple processes. First, based on the microstructure of the high-temperature alloy powder (12-14)Cr-(19-21)Co-(3-5)W-(3-5)Mo-(2-3)Ta-(3-4)Al-(2-4)Ti-(0.02-0.03)B-(0.04-0.06)Zr-(0.5-1.5)Nb-(0.001-0.02)C-the remainder Ni prepared by different processes, the temperature range of microstructure transformation for different processes is determined. Then, according to the different processes used for the high-temperature alloy powder, the high-temperature alloy powder is sieved into different particle size ranges. Finally, the high-temperature alloy powder is formed according to the above temperature range. After forming, γ' is the main reinforcing phase. The forming preparation method provided in this application balances alloying elements and forming processes, and sets matching temperature ranges for different processes based on the microstructure transformation characteristics of different processes, thereby achieving accurate customization of the forming process. Furthermore, the alloy powder provided in this application can be simultaneously applied to three forming preparation processes: wide-gap brazing, hot isostatic pressing, and laser additive manufacturing. This results in alloy dendrites and grains that are uniform and fine, with low porosity, good thermal stability, excellent mechanical properties, and good forming process performance. In addition, this application can use a combination of various testing and characterization methods for characterization, achieving horizontal comparability of results. Detailed Implementation

[0032] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims of the present invention.

[0033] Addressing the issue that existing high-temperature alloys often require a single process or have a low degree of alloying, this application, by balancing multiple alloying elements and various processing techniques, makes the provided high-temperature alloy powder material suitable for wide-gap brazing, hot isostatic pressing, and laser additive manufacturing, while ensuring the performance of the formed material, based on a carbon content reduction of more than 60% compared to similar traditional alloys. Furthermore, the microstructure and properties of the powder and bulk materials are characterized using a combination of synchrotron X-ray diffraction, focused ion beam scanning electron microscopy, transmission electron microscopy, and nanoscale hardness testing, enabling lateral performance comparisons. Specifically, this invention discloses a method for forming and preparing a high-alloy high-temperature alloy powder that can be used in multiple processes, including the following steps:

[0034] Based on the microstructure of powder or bulk materials prepared by different processes using high-temperature alloy powder, determine the temperature range for microstructure transformation under different processes;

[0035] Depending on the different processes used to process the high-temperature alloy powder, the powder is sieved into different particle size ranges, and then shaped according to the temperature range.

[0036] The composition of the high-temperature alloy powder, by mass percentage, is (12-14)Cr-(19-21)Co-(3-5)W-(3-5)Mo-(2-3)Ta-(3-4)Al-(2-4)Ti-(0.02-0.03)B-(0.04-0.06)Zr-(0.5-1.5)Nb-(0.001-0.02)C-the remainder Ni;

[0037] The different processes include wide-gap brazing, hot isostatic pressing (HIP) consolidation forming, or laser additive manufacturing.

[0038] In the forming and preparation method provided in this application, high-temperature alloy powder is first prepared using a vacuum induction melting process, specifically including the following steps:

[0039] Step 1: Prepare the raw materials for the master alloy ingot according to the elemental ratio of the high-temperature alloy powder;

[0040] Step 2: Prepare master alloy ingots by vacuum induction melting, wherein the vacuum pressure of the vacuum induction melting is <1 Pa, and the equipment capacity of the vacuum induction melting is 50~4000 kg;

[0041] Step 3: Remelt the master alloy ingot at a temperature of 1500~1600℃, a refining temperature of 1550~1600℃, a casting temperature of 1450~1550℃, and then prepare high-temperature alloy powder by gas atomization powder preparation at an atomization pressure of 2.5~5.5MPa.

[0042] Step 4: Sieve the prepared alloy powder to a particle size of <200μm to remove ultra-coarse powder and flaky powder. Set aside the sieved powder for later use.

[0043] In the above process, the raw materials prepared are those well known to those skilled in the art, and this application does not impose any special restrictions on them. The vacuum induction melting technique is well known to those skilled in the art, and this application does not impose any special restrictions on it. The remelting temperature is preferably 1550~1580℃, the refining temperature is preferably 1550~1580℃, and the casting temperature is preferably 1480~1520℃. The gas atomization powder preparation method is carried out according to methods well known to those skilled in the art. Preferably, the gas atomization powder preparation is carried out in a gas atomization powder preparation furnace with a capacity of 50~300kg, and the atomization pressure is preferably 3.5~5.0MPa. After final mechanical vibrating sieve sieving, high-temperature alloy powder with a particle size <200μm is obtained. Among them, the dendrite spacing of the fine powder with a particle diameter <32μm is 1.4μm, the dendrite spacing of the powder with a particle diameter of 75~100μm is 3μm, and the dendrite spacing of the coarse powder with a particle diameter of 100~150μm is 4μm. The high-temperature alloy powder described in this application is (12-14)Cr-(19-21)Co-(3-5)W-(3-5)Mo-(2-3)Ta-(3-4)Al-(2-4)Ti-(0.02-0.03)B-(0.04-0.06)Zr-(0.8-1.2)Nb-(0.005-0.015)C-the remainder Ni; specifically (12.2-13.6)Cr-(19.3-20.6)Co-(3.1-4.3)W-(3.3) -4.8)Mo-(2.2-2.7)Ta-(3.4-3.8)Al-(2.3-3.7)Ti-(0.02-0.03)B-(0.05-0.06)Zr-(0.9-1.1)Nb-(0.008-0.013)C-the remainder Ni; For example, the high-temperature alloy powder described in this application is 13Cr-20Co-4W-4Mo-3Ta-4Al-2Ti-0.02B-0.04Zr-1Nb-0.01C-the remainder Ni. The high-temperature alloy powder provided in this application has high W, Mo, and Ta content, and its C content is reduced by more than 60% compared with similar traditional alloys. The alloying elements are carefully balanced and matched with various hot working and forming processes, making the same alloy powder material suitable for wide-gap brazing (WGB) defect repair, hot isostatic pressing (HIP) consolidation forming of aero-engine turbine disks or laser additive manufacturing (AM) gas turbine integral turbine impellers, or preparation of corresponding alloy bulk materials. The microstructure and properties of the powder can be characterized by a combination of synchrotron radiation X-ray diffraction, focused ion beam scanning electron microscopy, transmission electron microscopy, and nanoscale hardness testing.

[0044] The high-temperature alloy powder described above can be applied to the following processes simultaneously:

[0045] The high-temperature alloy powder is used as a gap filling material to fill the wide gap repair part to be brazed.

[0046] Alternatively, hot isostatic pressing can be used to solidify high-temperature alloy powder into shape;

[0047] Alternatively, laser additive manufacturing can be used to rapidly melt and solidify high-temperature alloy powder into a solid.

[0048] After studying the microstructure transformation characteristics of the aforementioned high-temperature alloy powder, the applicant determined the following: the holding temperature for the wide-gap brazing defect repair process is the temperature range below the solidus line of the powder and below the critical temperature for the transformation of dendrites to equiaxed crystals; the characteristic temperature at which gas escapes from the powder surface is used as the powder degassing holding temperature; the temperature range between the critical temperature for the transformation of dendrites to equiaxed crystals and the solidus line temperature is used as the hot isostatic pressing temperature for the hot isostatic pressing consolidation forming process; the temperature range above the liquidus line temperature is used as the molten pool temperature range for laser additive manufacturing; and the temperature range of the solid-liquid two-phase region is used as the temperature range of the heat-affected zone for laser additive manufacturing.

[0049] More specifically, for the use of high-temperature alloy powder in wide-gap brazing processes, the high-temperature alloy powder is used as a gap support material to fill the gap to be brazed. The process is as follows:

[0050] High-temperature alloy powder was sieved to a particle size range of 75-150μm and filled into the gap space to be repaired as a support material. It was then mixed with low-melting-point brazing filler with a particle size of <20μm, preheated to 1100℃, held for 2 hours, then heated to 1150℃ and held for 4 hours. After cooling to room temperature, the low-melting-point brazing filler completely melted, while the high-temperature alloy powder remained solid and no obvious internal microstructure transformation occurred.

[0051] Alternatively, for high-temperature alloy powders used in hot isostatic pressing (HIP) solidification processes, specifically:

[0052] High-temperature alloy powder was sieved into a particle size range of 0~63μm. The alloy powder was then compacted, degassed, and sealed in a stainless steel sheath. The compaction time was >20s, and the frequency was 60Hz. The vacuum pressure was below 10℃. -3 Under high-temperature vacuum degassing conditions, the characteristic temperature range of the extraction of various gases from the alloy powder was determined by TPD-MS. Based on the characteristic temperatures, the combined temperature degassing parameters were determined as follows: temperature 120~180℃ / 1~3h + 250~350℃ / 1~3h + 550~600℃ / 1~3h, and the total degassing time > 5h. The cladding was sealed by argon arc welding and then placed in a hot isostatic press for hot isostatic pressing and solidification. The hot isostatic pressing parameters were 1155~1200℃ / 150~200MPa / >3h.

[0053] In the above-mentioned hot isostatic pressing consolidation forming process, the degassing parameters are specifically 130~150℃ / 1~3h +280~300℃ / 1~3h +560~580℃ / 1~3h, and the hot isostatic pressing parameters are 1160~1185℃ / 160~180MPa / 3.5~5h.

[0054] Alternatively, the high-temperature alloy powder may be used in a laser additive manufacturing process, which involves rapidly melting and solidifying the high-temperature alloy powder, specifically:

[0055] High-temperature alloy powder is sieved to a particle size range of 53~150μm, and then placed into a laser additive manufacturing equipment for shaping. The laser power is 700~1000w and the scanning speed is 800~1000mm / s.

[0056] In the above-mentioned laser additive manufacturing process, the laser power is 800~900w and the scanning speed is 900mm / s.

[0057] The dendrite spacing of the high-temperature alloy powder used to support the powder region after wide-gap brazing is 5μm. The dendrite spacing of the alloy prepared by laser additive manufacturing is 10μm. The microstructure of the alloy prepared by hot isostatic pressing is an equiaxed fine-grained microstructure with a grain size of 26μm.

[0058] This application then heat-treats the formed alloy, with the solution heat treatment temperature being within 50°C above or below the average value of the precipitation and dissolution temperatures of the main strengthening phase (such as γ' phase). Specifically, the heat treatment regime includes: 1115~1135°C / 1~4h oil cooling + 800~850°C / 16~20h air cooling or oil cooling, or 1155~1195°C / 1~4h oil cooling + 800~850°C / 16~20h air cooling or oil cooling; more specifically: 1125~1135°C / 2~3h oil cooling + 820~830°C / 16~18h air cooling, or 1175~1180°C / 2~3h oil cooling + 820~830°C / 16~18h air cooling or oil cooling.

[0059] Furthermore, the forming preparation method of this application also includes separate characterization and mechanical property testing of the high-temperature alloy powder and the formed product, wherein the characterization specifically includes:

[0060] Synchrotron X-ray diffraction (XRD) was used to rapidly characterize trace precipitates, including γ' and carbide phases, in highly alloyed high-temperature alloy powders. The XRD energy was 75 keV, the wavelength λ was 0.163137 Å, the X-ray spot size was 100 μm, and the exposure time was 2 s. Diffraction ring patterns of the alloy powders were obtained. The results showed that trace phases, including γ' and MC carbides, existed in the <32 μm particle size range. More trace phases, including γ' and MC carbides, were present in the 75–100 μm and 100–150 μm particle size ranges. Focused ion beam scanning electron microscopy (FEM) and transmission electron microscopy (TEM) were used to characterize the 75–100 μm particle size range powders. Selected area electron diffraction (SEG) results indicated a superlattice structure in the powder, confirming the presence of γ' in the original powder of this particle size range, consistent with the synchrotron XRD results.

[0061] The bulk materials formed by powder forming were characterized by XRD using the same method as described above, including the wide-gap brazed support powder region, the hot isostatic pressing consolidation alloy, and the additive manufacturing high-temperature alloy. The results showed that the main constituent phases of the wide-gap brazed support powder region, the hot isostatic pressing alloy, and the laser additive manufacturing alloy included trace phases, which included γ, γ', and MC carbides.

[0062] By comparing the XRD curves of powdered and bulk alloys, we can understand the precipitation patterns and microstructure inheritance characteristics of precipitates from powder to bulk alloys.

[0063] The mechanical property test specifically involves using nano-hardness testing to test the hardness of high-temperature alloy powder and bulk materials, and making a horizontal comparison to verify the effectiveness and rationality of the process.

[0064] The forming and preparation method provided in this application, through the matching design of composition and process, enables high-temperature alloy powder materials to be applicable to multiple process routes, including wide-gap brazing, hot isostatic pressing, and laser additive manufacturing. This achieves "one material, multiple uses" for high-alloy high-temperature alloy powder materials, reducing the material R&D cost of products by more than 50%. At the same time, high-temperature alloy powder materials are also suitable for multiple applications, including wide-gap brazing to repair defects, hot isostatic pressing to prepare turbine disks, and laser additive manufacturing to prepare integral turbine impellers.

[0065] Meanwhile, the high-temperature alloy powder of this application adopts a lower carbon content design (carbon content reduced by more than 60% compared with traditional alloys) to reduce the content of hard and brittle carbide phases, reduce the size of precipitated phases, and reduce the tendency of stress concentration to cause cracking, thus providing support for the application of rapid solidification processes such as additive manufacturing (especially laser coaxial powder feeding process). In addition, after the carbon content of the high-temperature alloy powder is significantly reduced, it is difficult to identify carbides. Synchrotron radiation X-ray diffraction and amorphous capillary containers can effectively characterize the trace precipitates of high-temperature alloy powders. The microstructure of powder and bulk materials is characterized by a combination of synchrotron radiation X-ray diffraction and electron microscopy, taking into account the correlation between trace and fine precipitates in the powder and the genetic characteristics of bulk materials. The material properties are characterized by a combination of nano-hardness indentation and traditional mechanical property testing, taking into account the boundary characteristics of fine powder particles and the genetic characteristics of mechanical properties of bulk materials.

[0066] To further understand the present invention, the following detailed description of the forming and preparation method of high-alloyed high-temperature alloy powder with multiple shared processes provided by the present invention is provided in conjunction with the embodiments. The scope of protection of the present invention is not limited by the following embodiments.

[0067] Example 1

[0068] 1) The alloy composition is 13Cr-20Co-4W-4Mo-3Ta-4Al-2Ti-0.02B-0.04Zr-1Nb-0.01C-balance Ni (wt%). A high-temperature alloy master alloy with the above composition was prepared by vacuum induction melting. Alloy powder was prepared by vacuum induction remelting and gas atomization, specifically as follows:

[0069] Step 1: Prepare the raw materials for making the master alloy ingot;

[0070] Step 2: Prepare the master alloy ingot using vacuum induction melting. The vacuum pressure during the melting process is <1 Pa. The crucible used to prepare the alloy ingot can hold 500 kg of master alloy.

[0071] Step 3: Remelt the master alloy ingot from Step 2. The remelting temperature is 1550℃, the refining temperature is 1580℃, the casting temperature is 1520℃, and then prepare high-temperature alloy powder by gas atomization powder preparation. The atomization pressure is 3.5MPa, and the powder weight prepared in a single furnace is 150kg.

[0072] Step 4: The prepared alloy powder is sieved using a mechanical vibrating screen to remove ultra-coarse powder and flaky powder with a particle size <200μm. The sieved powder is then set aside for use.

[0073] The alloy powder materials prepared above are also suitable for wide-gap brazing defect repair, hot isostatic pressing to form aero-engine turbine disks or laser additive manufacturing of integral turbine impellers for gas turbines, or for preparing corresponding bulk alloy materials. The microstructure and properties of the powder and bulk alloys are characterized by a combination of synchrotron radiation X-ray diffraction, focused ion beam scanning electron microscopy, transmission electron microscopy and nanohardness.

[0074] 2) After the high-temperature alloy powder is prepared, it is subjected to different forming processes: the high-alloy high-temperature alloy powder is filled into the gap to be brazed as a gap support material; or, the high-alloy high-temperature alloy powder is solidified into shape by hot isostatic pressing; or, the high-alloy high-temperature alloy powder is rapidly melted and solidified into shape by laser additive manufacturing.

[0075] 3) Theoretically, the temperature ranges for the different processes mentioned above are determined as follows: the temperature below the solidus line of the powder and below the critical temperature for the transformation of dendrites to equiaxed crystals is selected as the holding temperature for alloy large gap brazing; the temperature range between the critical temperature for the transformation of dendrites to equiaxed crystals in the powder and the solidus line temperature is selected as the hot isostatic pressing temperature of the alloy; the temperature range above the liquidus line temperature (forming a completely bulk material) is selected as the molten pool temperature range for additive manufacturing, and the temperature range in the solid-liquid two-phase region is selected as the heat-affected zone temperature range for additive manufacturing.

[0076] 4) Based on the above theory, the forming process of high-temperature alloy powder is carried out in the following manner:

[0077] High-temperature alloy powder was sieved to a particle size range of 75~150μm and filled into the gap space to be repaired by wide-gap brazing as a support material. Low-melting-point brazing filler with a particle size of <20μm was then added and mixed. The mixture was heated to 1100℃ for preheating and held for 2 hours. It was then heated to 1150℃ and held for 4 hours. After cooling to room temperature, the low-melting-point brazing filler completely melted, while the support powder material remained solid and no obvious internal microstructure transformation occurred.

[0078] Alternatively, the high-temperature alloy powder is sieved into a particle size range of 0~63μm. The alloy powder is then compacted, degassed, and sealed in a stainless steel sheath. The compaction time is >20 s, the frequency is 60Hz, and the vacuum pressure is below 10... -3 Under high temperature vacuum degassing conditions, the characteristic temperature range of multiple gases escaping from the alloy powder was determined by TPD-MS, and the combined temperature degassing parameters were determined. The temperature was 150℃ / 1h + 300℃ / 3h + 550℃ / 3h, and the total degassing time was >5h. The cladding was sealed by argon arc welding, and the high temperature alloy powder cladding was placed in a hot isostatic press for hot isostatic pressing and solidification. The hot isostatic pressing parameters were 1185℃ / 180MPa / 3.5h.

[0079] Alternatively, the high-temperature alloy powder is sieved to a particle size range of 53~150μm, and the sieved high-temperature alloy powder is placed into a laser additive manufacturing equipment for forming, with a laser power of 800w and a scanning speed of 900mm / s.

[0080] 5) The formed block material is heat-treated. The solution treatment temperature is selected above the precipitation and re-dissolution temperature of the main strengthening phase of the alloy, specifically 1175℃ / 4h oil cooling + 830℃ / 16h air cooling.

[0081] 6) The precipitated phases of the alloy and powder were characterized using synchrotron X-ray diffraction, focused ion beam scanning electron microscopy, and transmission electron microscopy. The steps are as follows:

[0082] Step 1: The trace precipitates in the high-temperature alloy powder, including γ' and carbide phases, were rapidly characterized using synchrotron X-ray diffraction (XRD). The synchrotron X-ray energy was 75 keV, the wavelength λ was 0.163137 Å, the X-ray spot size was 100 μm, and the exposure time was 2 s. Diffraction ring patterns of the alloy powder were obtained. The powder sample was placed in an amorphous capillary container with a diameter of 1 mm and a wall thickness of 0.1 mm. The results showed that trace phases, including γ' and MC carbides, were present in the powder with a particle size of <32 μm. The powder with a particle size of 75~100 μm and 100~150 μm had more trace phases, including γ' and MC carbides. The powder with a particle size of 75~100 μm was characterized by focused ion beam scanning electron microscopy and transmission electron microscopy. Selected area electron diffraction results showed that the powder had a superlattice structure, proving that the original powder in this particle size range contained γ', which was consistent with the results of synchrotron X-ray diffraction.

[0083] Step 2: The bulk material after powder forming was characterized by XRD using the same method as in Step 1, including the wide-gap brazed support powder region, the hot isostatic pressing consolidation alloy, and the laser additive manufacturing high-temperature alloy. The results show that the main constituent phases of the wide-gap brazed support powder region, the hot isostatic pressing alloy, and the laser additive manufacturing alloy include trace phases, which include γ, γ', and MC carbides.

[0084] Step 3: Compare the XRD curves of powder and bulk materials to understand the precipitation pattern and microstructure inheritance characteristics of the precipitated phase from powder to bulk alloy.

[0085] The microstructure of the high-temperature alloy powder, wide-gap brazing support powder, and additive manufacturing alloy, as determined by the above characterization methods, is fine dendrites. The dendrite spacing of the original powder particles (<32 μm diameter) is 1.4 μm, the dendrite spacing of the powder with a particle diameter of 75-100 μm is 3 μm, and the dendrite spacing of the coarse powder with a particle diameter of 100-150 μm is 4 μm. After using the high-temperature alloy powder for wide-gap brazing, the dendrite spacing in the support powder region is 5 μm; the dendrite spacing of the alloy prepared by additive manufacturing is 10 μm; and the dendrite spacing of the alloy prepared by hot isostatic pressing is... The alloy microstructure is an equiaxed fine-grained structure with a grain size of 26 μm. The nanohardness test was conducted by controlling the indentation depth at 50 nm. The nanohardness of the high-temperature alloy fine powder with a particle size of <32 μm was 12.43 GPa, the nanohardness of the 100~150 μm powder was 14.17 GPa, the nanohardness of the wide gap brazed (WGB) support powder was 9.41 GPa, the nanohardness of the hot isostatic pressing (HIP) block was 14.71 GPa, and the nanohardness of the additive manufacturing (AM) block was 14.27 GPa. The obtained alloy microstructure is fine, uniform, and free of pores and cracks.

[0086] Example 2

[0087] The forming process is the same as in Example 1, except that the high-temperature alloy after hot isostatic pressing is subjected to heat treatment. The solution temperature during heat treatment is selected below the precipitation and re-dissolution temperature of the main strengthening phase of the alloy. Specifically, the heat treatment parameters are 1125℃ / 4h oil cooling + 830℃ / 16h air cooling or oil cooling. The nanohardness of the hot isostatic pressing (HIP) alloy at an indentation depth of 50nm is 13.56GPa. The resulting alloy has a fine, uniform structure without pores or cracks.

[0088] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0089] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for forming and preparing high-alloyed high-temperature alloy powder using multiple processes, comprising the following steps: Based on the microstructure of powder or bulk materials prepared by different processes using high-temperature alloy powder, the characteristic temperature range of microstructure transformation in different processes is determined. Depending on the different processes used to process the high-temperature alloy powder, the powder is sieved into different particle size ranges, and then shaped and prepared according to the temperature range. The composition of the high-temperature alloy powder, by mass percentage, is (13-13.6)Cr-(19.3-20.6)Co-(3.1-4.3)W-(3.3-4.8)Mo-(2.2-2.7)Ta-(3.4-3.8)Al-(2.3-3.7)Ti-(0.02-0.03)B-(0.05-0.06)Zr-(0.9-1.1)Nb-(0.008-0.013)C-the balance being Ni; The high-temperature alloy powder is also suitable for the following processes: The high-temperature alloy powder is used as a gap filling material to fill the wide gap repair part to be brazed. Alternatively, hot isostatic pressing can be used to solidify high-temperature alloy powder into shape; Alternatively, laser additive manufacturing can be used to rapidly melt and solidify high-temperature alloy powder into shape; The different processes include wide-gap brazing, hot isostatic pressing, or laser additive manufacturing. The holding temperature for wide-gap brazing is defined as the temperature range below the solidus line of the powder and below the critical temperature at which dendrites transform into equiaxed crystals. The characteristic temperature at which gas escapes from the powder surface is taken as the powder degassing and heat preservation temperature, and the temperature range between the critical temperature of dendrite transformation to equiaxed crystal and the solidus temperature is taken as the hot isostatic pressing temperature of the hot isostatic pressing solidification forming process. The temperature range of the molten pool in laser additive manufacturing is defined as the temperature above the liquidus temperature, and the temperature range of the solid-liquid two-phase region is defined as the temperature range of the heat-affected zone in laser additive manufacturing. The method for preparing the high-temperature alloy powder includes the following steps: Step 1: Prepare the raw materials for the master alloy ingot according to the elemental ratio of the high-temperature alloy powder; Step 2: Prepare the master alloy ingot by vacuum induction melting, wherein the vacuum pressure of the vacuum induction melting is <1 Pa; Step 3: Remelt the master alloy ingot at a temperature of 1500~1600℃, a refining temperature of 1550~1600℃, and a casting temperature of 1450~1550℃. Then, prepare high-temperature alloy powder through a gas atomization powder making furnace with a capacity of 50~300kg and an atomization pressure of 2.5~5.5MPa. Step 4: Sieve the prepared alloy powder to a particle size of <200μm.

2. The forming and preparation method according to claim 1, characterized in that, The particle size of the high-temperature alloy powder in the wide-gap brazing process is 75~150μm, the particle size of the high-temperature alloy powder in the hot isostatic pressing consolidation forming process is 0~63μm, and the particle size of the high-temperature alloy powder in the laser additive manufacturing process is 53~150μm.

3. The molding and preparation method according to claim 1, characterized in that, The high-temperature alloy powder used in wide-gap brazing processes involves filling the gaps to be brazed with the high-temperature alloy powder as a gap support material. The specific process is as follows: High-temperature alloy powder was sieved to a particle size range of 75~150μm and filled into the gap space to be repaired as a support material. It was mixed with low-melting-point brazing filler with a particle size of <20μm, heated to 1100℃ for preheating, held for 2 hours, then heated to 1150℃ for 4 hours, and cooled to room temperature. The low-melting-point brazing filler completely melted, while the high-temperature alloy powder remained solid and no obvious internal microstructure transformation occurred.

4. The forming and preparation method according to claim 1, characterized in that, The high-temperature alloy powder is used in a hot isostatic pressing (HIP) solidification forming process, specifically: High-temperature alloy powder was sieved into particle size ranges of 0~63μm, then compacted, degassed, and sealed in a stainless steel sheath. The compaction time was >20s, the frequency was 60Hz, and the vacuum pressure was below 10. -3 Under the condition of Pa, high-temperature vacuum degassing is performed at a temperature of 120~180℃ / 1~3h + 250~350℃ / 1~3h + 550~600℃ / 1~3h, and the total degassing time is >5h. The stainless steel cladding is then placed in a hot isostatic press and solidified by hot isostatic pressing at a temperature of 1155~1200℃, a pressure of 150~200MPa, and a time of >3h.

5. The molding and preparation method according to claim 1, characterized in that, The high-temperature alloy powder used in laser additive manufacturing processes involves rapidly melting and solidifying the high-temperature alloy powder into a shape, specifically: High-temperature alloy powder is sieved to a particle size range of 53~150μm, and then placed into a laser additive manufacturing equipment for shaping. The laser power is 700~1000w and the scanning speed is 800~1000mm / s.

6. The molding and preparation method according to any one of claims 1 to 5, characterized in that, The forming process also includes heat treatment, with the solution heat treatment temperature being within 50°C above or below the average precipitation and dissolution temperature of the main strengthening phase. Specifically, the heat treatment regime includes: 1115~1135°C / 1~4h oil cooling + 800~850°C / 16~20h air cooling or oil cooling, or 1155~1195°C / 1~4h oil cooling + 800~850°C / 16~20h air cooling or oil cooling.

7. The molding and preparation method according to any one of claims 1 to 5, characterized in that, The preparation method further includes characterization and mechanical property testing of the high-temperature alloy powder and the shaped powder, wherein the characterization specifically includes: The trace precipitates of high-temperature alloy powder, including γ' strengthening phase and carbide phase, were rapidly characterized by synchrotron X-ray diffraction. The energy of the synchrotron X-ray was 70~80 keV, the wavelength λ was 0.163137 Å, the X-ray spot size was 100~200 μm, and the exposure time was 1~2 s. The diffraction ring pattern of the alloy powder was obtained. The bulk materials formed by powder molding were characterized by XRD. The bulk materials included wide-gap brazed support powder regions, hot isostatically pressed alloys, and high-temperature alloys manufactured by laser additive manufacturing. By comparing the XRD curves of high-temperature alloy powder and bulk materials, we can understand the precipitation law and microstructure inheritance characteristics of precipitated phases from powder to bulk materials. The mechanical property test specifically involves using nano-hardness testing to test the hardness of high-temperature alloy powder and bulk materials.