Ultrasonic post-treatment methods for single-crystal or uniform columnar polycrystalline nickel-based superalloys

Abstract

This invention belongs to the field of post-processing technology for single-crystal or homogeneous polycrystalline materials with a certain structure, specifically relating to an ultrasonic post-processing method for single-crystal or homogeneous columnar polycrystalline nickel-based superalloys. This invention performs ultrasonic solution treatment on precipitation-strengthened nickel-based superalloys with a single-crystal or homogeneous polycrystalline structure in an ultrasonic and thermal field. The ultrasonic solution treatment includes a heating stage, a holding stage, and a cooling stage. An ultrasonic field is applied during the holding and cooling stages. Simultaneously, the ultrasonic frequency f0 and amplitude A of the ultrasonic field are defined during the ultrasonic solution treatment. The set temperature of the holding stage is determined based on the target temperature of the precipitation-strengthened nickel-based superalloy, the amplitude transformer cooling compensation temperature, and the ultrasonic thermal effect counter-compensation temperature. This invention, through ultrasonic-coupled heat treatment, controls the alloy precipitates to obtain precipitates with small size, high density, and uniform distribution, effectively improving the material's mechanical properties at both room temperature and high temperature.

Description

Technical Field

[0001] This invention belongs to the field of post-processing technology for single crystal or uniform polycrystalline materials with a certain structure, specifically relating to an ultrasonic post-processing method for single crystal or uniform columnar polycrystalline nickel-based superalloys. Background Technology

[0002] To meet the requirements of the service environment, high-temperature turbine blades of aero-engines and gas turbines require the use of single-crystal, oriented columnar polycrystalline nickel-based superalloy materials. The strengthening mechanism is mainly solid solution strengthening and aging strengthening. The preparation process mainly includes: (1) preparing single-crystal / oriented columnar polycrystalline materials using directional solidification technology; (2) post-treatment (solution treatment and aging treatment). The post-treatment process is crucial. Through the solution treatment process, some harmful phases are melted back and the solute is homogenized, so that fine and densely distributed precipitated strengthening phases are precipitated during the subsequent cooling process; further, the uniform growth and morphology correction of the precipitated strengthening phases are achieved through the aging treatment process. The effect of the solution treatment directly determines the precipitation behavior of the precipitated phases and the final strengthening effect during the subsequent aging treatment. If the solid solution is insufficient or the precipitated phases are unevenly distributed, the strengthening phases after aging treatment will be coarse and dispersed, making it difficult to obtain ideal microstructure and mechanical properties. Therefore, solution treatment largely determines the distribution of dissolved elements in the matrix and the morphology of the precipitated strengthening phase, which has a significant impact on the mechanical properties of the final high-temperature alloy single crystal and oriented columnar polycrystalline blades.

[0003] However, traditional heat treatment processes have significant limitations in the post-treatment solution treatment stage of precipitation-strengthened nickel-based superalloy single crystals and homogeneous polycrystalline materials. Although precipitates form during cooling after the solution treatment stage, the number of nuclei is limited. These newly formed precipitates further grow during subsequent aging, resulting in an inability to obtain high-density, fine precipitates and consequently poor high-temperature mechanical properties. These defects severely restrict the further upgrading and application of this type of alloy in high-end equipment fields such as aero-engine blades and aerospace structural components, especially failing to meet the stringent material requirements of next-generation high thrust-to-weight ratio aero-engines and hypersonic vehicles. Therefore, there is an urgent need to develop a new technology capable of controlling parameters such as the nucleation rate, quantity, and size of the second phase during the solution treatment stage to achieve controllable refinement of the second phase grains. Summary of the Invention

[0004] The purpose of this invention is to provide an ultrasonic post-processing method for single-crystal or uniform columnar polycrystalline nickel-based superalloys, thereby controlling the alloy precipitates to obtain precipitates with small size, high distribution density, and uniform distribution.

[0005] To achieve the objectives of this invention, the following technical solutions are provided: An ultrasonic post-processing method for single-crystal or uniform columnar polycrystalline nickel-based superalloys includes the following steps: In an ultrasonic field and a thermal field, a precipitation-strengthened nickel-based superalloy is subjected to ultrasonic solution treatment, wherein the as-cast microstructure of the precipitation-strengthened nickel-based superalloy is a single crystal or a uniform columnar polycrystalline structure; the ultrasonic solution treatment includes a heating stage, a holding stage and a cooling stage, wherein an ultrasonic field is applied in the holding stage and the cooling stage. The set temperature of the heat preservation stage is T = T0 + T1 - T2, where T0 is the target temperature of precipitation-strengthened nickel-based superalloy, T1 is the ultrasonic cooling compensation temperature, and T2 is the ultrasonic thermal effect reverse compensation temperature. During the ultrasonic solution treatment, the ultrasonic frequency f0 of the ultrasonic field satisfies 15kHz ≤ f0 ≤ 25kHz, and the amplitude A satisfies 1μm. , where σ y ρ and c represent the yield strength, density, and velocity of sound of the precipitation-strengthened nickel-based superalloy under the set temperature conditions during the heat preservation stage.

[0006] Preferably, the ultrasonic field is achieved by a rigid connection between an ultrasonic amplitude transformer and a precipitation-strengthened nickel-based high-temperature alloy, wherein the ultrasonic amplitude transformer is made of a high-temperature, high-strength alloy; and the rigid connection includes a threaded connection or a clamping connection.

[0007] Preferably, the target temperature T0 of the precipitation-strengthened nickel-based superalloy is 1350~1550K, and the ultrasonic cooling compensation temperature T1 = α·h·S·R(T0-T s ), where α is the proportionality coefficient, h is the convective heat transfer coefficient, S is the heat transfer area, R is the equivalent thermal resistance of the ultrasonic amplitude transformer, and T s Temperature of the cooling medium; The ultrasonic thermal effect countercompensation temperature T2= Where E is the Young's modulus of the precipitation-strengthened nickel-based superalloy, tanδ is the loss factor of the precipitation-strengthened nickel-based superalloy, k is the thermal conductivity of the precipitation-strengthened nickel-based superalloy, L is the length of the cylindrical precipitation-strengthened nickel-based superalloy along the vibration direction, S0 is the cross-sectional area of ​​the cylindrical precipitation-strengthened nickel-based superalloy, f0 is the ultrasonic frequency of the ultrasonic field, and A is the amplitude of the ultrasonic field.

[0008] Preferably, the amplitude A of the ultrasonic field is 1~3μm; the yield strength σ of the precipitation-strengthened nickel-based superalloy under the set temperature conditions during the heat preservation stage is... y Satisfying σ y ≥Eε max Where E is the Young's modulus of precipitation-strengthened nickel-based superalloys, and ε max ε is the maximum strain amplitude at the end face of the ultrasonic amplitude transformer. max Satisfying ε max / A max =(D2 / D1) 1 / 2Where D1 is the diameter of the precipitation-strengthened nickel-based superalloy, and D2 is the diameter of the ultrasonic amplitude transformer.

[0009] Preferably, the ultrasonic field is applied during the heat preservation stage 0-2 hours after the start of the heat preservation stage; the heat preservation time after the ultrasonic field is applied during the heat preservation stage is 1-3 hours.

[0010] Preferably, the heating stage is carried out in an inert gas, and the heating stage includes a first heating stage and a second heating stage; the first heating stage includes heating from room temperature to 1470~1490K, and the second heating stage includes heating from 1470~1490K to the set temperature of the heat preservation stage.

[0011] Preferably, the heating rate in the first heating stage is 5~10K / min, and the holding time after heating to 1470~1490K is 1~2h; the heating rate in the second heating stage is 5~10K / min.

[0012] Preferably, the cooling stage involves cooling the set temperature of the heat preservation stage to room temperature, the cooling is air cooling, and the cooling rate is 30~150K / min; an ultrasonic field is applied throughout the cooling stage, and the amplitude A of the ultrasonic field applied in the cooling stage is the same as that in the heat preservation stage.

[0013] Preferably, the ultrasonic solution treatment is followed by an aging treatment.

[0014] Preferably, the timeliness processing includes a first timeliness processing and a second timeliness processing; The first aging treatment includes a first heating stage, a first holding stage, and a first cooling stage; the first heating stage includes heating from room temperature to 1350~1400K at a heating rate of 5~10K / min, the holding time of the first holding stage is 3~5h, and the first cooling stage includes natural cooling in air to room temperature at a cooling rate of 30~150K / min. The second aging treatment includes a second heating stage, a second holding stage, and a second cooling stage. The second heating stage includes heating from room temperature to 1000~1200K at a heating rate of 2~5K / min. The holding time of the second holding stage is 18~22h. The second cooling stage includes natural cooling to room temperature in air.

[0015] The ultrasonic post-processing method for single-crystal or uniform columnar polycrystalline nickel-based superalloys provided by this invention has at least the following technical effects: First, this invention applies a continuous ultrasonic field with a specific frequency and amplitude to the alloy material within the critical temperature range of the solution treatment, thereby increasing the number of nucleation particles in the system and optimizing their distribution. The ultrasonic field can reduce the nucleation energy barrier of the precipitated phase, promote the formation of a large number of uniform and dispersed nucleation sites, and thus guide the precipitated phase to solidify or undergo phase transformation with a higher nucleation rate during the subsequent temperature-controlled cooling process, ultimately obtaining a small-sized, uniformly distributed, and regularly morphologically regular strengthening phase, achieving precise control of the material's microstructure and mechanical properties.

[0016] Secondly, this invention utilizes the mechanical vibration generated within the material by ultrasonic energy to significantly promote the diffusion and rearrangement of solute atoms, effectively improving elemental uniformity and reducing component segregation, thereby enhancing the nucleation rate. Simultaneously, the introduction of the ultrasonic field reduces the mismatch between the matrix phase and the precipitated phase, significantly lowering the critical nucleation radius of the precipitated phase. This creates favorable conditions for the uniform nucleation of high-density, fine-grained precipitates and contributes to the increased nucleation rate. The method provided by this invention achieves grain refinement effects that are difficult to achieve with traditional heat treatment techniques.

[0017] Furthermore, the method provided by this invention uses ultrasonic waves as a control means, which has significant advantages such as being green, environmentally friendly, efficient, and energy-saving. By introducing a highly efficient ultrasonic field into the traditional heat treatment process, this method eliminates the need for adding additional alloying elements or complex process equipment, and also avoids significantly extending the processing time or increasing the processing temperature. Thus, while achieving the preparation of high-performance materials, it significantly reduces energy consumption and process costs, which aligns with the development concept of green manufacturing.

[0018] Furthermore, by precisely controlling the frequency, amplitude, and duration of ultrasonic parameters, this invention can directly influence the nucleation and growth kinetics of precipitated phases. Through the synergistic combination of ultrasonic parameters and heat treatment processes, precise control over the size, distribution, and morphology of precipitated phases can be achieved, further enhancing the precipitation strengthening effect and ultimately significantly improving the strength, hardness, and high-temperature mechanical properties of the alloy.

[0019] The precipitation-strengthened nickel-based superalloy prepared by the method provided in this invention has a significantly optimized microstructure, with the size of the γ' strengthening phase being significantly refined and its distribution uniformity greatly improved, and the average size of the precipitated phase being controllable to below several hundred nanometers. At the same time, the room temperature and high temperature mechanical properties of the alloy are enhanced, providing an advanced and reliable material processing technology for the manufacture of high-performance aerospace engine hot-end components. Attached Figure Description

[0020] Figure 1 A flowchart of an ultrasonic post-treatment method for precipitation-strengthened nickel-based superalloys with single-crystal or uniform polycrystalline structures provided by the present invention; Figure 2Comparative microstructures of DZ125 nickel-based precipitation-strengthened alloys in Example 1 and Comparative Example 1 are shown in the diagram. Figure 3 Comparative figures show the microstructure of the DZ125 nickel-based precipitation-strengthened alloy in Example 2 and Comparative Example 2. Figure 4 This is a comparison chart of the tensile properties of DZ125 nickel-based precipitation-strengthened alloys in Example 2 and Comparative Example 2. Detailed Implementation

[0021] This invention provides an ultrasonic post-processing method for single-crystal or uniform columnar polycrystalline nickel-based superalloys, comprising the following steps: In an ultrasonic field and a thermal field, a precipitation-strengthened nickel-based superalloy is subjected to ultrasonic solution treatment, wherein the as-cast microstructure of the precipitation-strengthened nickel-based superalloy is a single crystal or a uniform columnar polycrystalline structure; the ultrasonic solution treatment includes a heating stage, a holding stage and a cooling stage, wherein an ultrasonic field is applied in the holding stage and the cooling stage. The set temperature of the heat preservation stage is T = T0 + T1 - T2, where T0 is the target temperature of precipitation-strengthened nickel-based superalloy, T1 is the ultrasonic cooling compensation temperature, and T2 is the ultrasonic thermal effect reverse compensation temperature. During the ultrasonic solution treatment, the ultrasonic frequency f0 of the ultrasonic field satisfies 15kHz ≤ f0 ≤ 25kHz, and the amplitude A satisfies 1μm. , where σ y ρ and c represent the yield strength, density, and velocity of sound of the precipitation-strengthened nickel-based superalloy under the set temperature conditions during the heat preservation stage.

[0022] In this invention, unless otherwise specified, all raw materials used in the preparation are preferably commercially available products well known to those skilled in the art.

[0023] In one embodiment of the present invention, the precipitation-strengthened nickel-based superalloy is a cast precipitation-strengthened nickel-based superalloy. In terms of alloy composition, it can be a nickel-based precipitation-strengthened nickel-based superalloy or a copper-based precipitation-strengthened nickel-based superalloy. The precipitation-strengthened nickel-based superalloy used in this embodiment is a cast DZ125 alloy. The precipitation-strengthened nickel-based superalloy is cylindrical with a diameter D1 of 10 mm. The cast precipitation-strengthened nickel-based superalloy is prepared through smelting and machining. The present invention does not impose any special limitations on the smelting and machining processes; conventional smelting and machining techniques in the art can be used. The present invention performs precision machining on the precipitation-strengthened nickel-based superalloy, specifically by machining one end of the precipitation-strengthened nickel-based superalloy to prepare an M6 external thread. The pitch, accuracy, engagement length, and dimensions of the M6 ​​external thread all conform to the provisions of GB / T196-2003 "Basic Dimensions of Ordinary Threads" and GB / T 197-2018 "Tolerances of Ordinary Threads".

[0024] The ultrasonic solution treatment described in this invention includes a heating stage. In the first heating stage, the as-cast precipitation-strengthened nickel-based superalloy completes a preliminary solution diffusion process, and in the second heating stage, the alloying elements are fully homogenized. During the heating stage of the ultrasonic solution treatment, the as-cast alloy mainly undergoes internal stress release, recovery and recrystallization, second-phase dissolution or spheroidization, and non-equilibrium phase transformation, resulting in a more homogeneous composition. Excessive heating during the heating stage can easily generate thermal stress, while excessively slow heating may lead to grain growth.

[0025] The ultrasonic solution treatment described in this invention includes a heat preservation stage. This invention adopts a treatment method of first heat preservation for 1 to 2 hours, followed by the application of an ultrasonic field, thereby significantly improving the nucleation rate of the precipitated phase and achieving sufficient refinement of the precipitated phase.

[0026] In one embodiment of the present invention, the ultrasonic field is achieved by a rigid connection between an ultrasonic amplitude transformer and the precipitation-strengthened nickel-based superalloy. In another embodiment, the ultrasonic amplitude transformer is made of a high-temperature resistant material, further comprising 45 steel, titanium alloy, or nickel-based superalloy, specifically TC4 or 45 steel; one end of the ultrasonic amplitude transformer is a working section, and the end of the working section is provided with an internal thread that mates with an M6 external thread; the diameter D2 of the ultrasonic amplitude transformer is 10-20 mm, and its length is 250-350 mm. The ultrasonic amplitude transformer of the present invention can mechanically amplify, match, and efficiently transmit the minute mechanical vibrations generated by the transducer to meet the requirements of experiments or processes for amplitude, force, and impedance.

[0027] In one embodiment of the present invention, the rigid connection includes a threaded connection. The present invention rigidly connects the precipitation-strengthened nickel-based superalloy to the ultrasonic amplitude transformer, ensuring effective and stable transmission of acoustic energy from the ultrasonic amplitude transformer to the precipitation-strengthened nickel-based superalloy. The threaded rigid connection ensures a secure connection between the precipitation-strengthened nickel-based superalloy and the ultrasonic amplitude transformer, enabling precise transmission of vibration modes and frequencies, reducing acoustic energy loss at the interface, and preventing loosening, displacement, or deformation at the connection point caused by non-rigid connections, which could damage the precipitation-strengthened nickel-based superalloy.

[0028] In one embodiment of the present invention, a heat insulation sleeve is further provided outside the ultrasonic amplitude transformer. The heat insulation sleeve is made of mullite fiber and has a thickness of 1-2 cm. The heat insulation sleeve is cylindrical and completely covers the outside of the working section of the ultrasonic amplitude transformer, specifically covering the portion of the ultrasonic amplitude transformer placed inside a heat treatment device (such as a muffle furnace). The present invention provides a heat insulation sleeve outside the working section of the ultrasonic amplitude transformer to ensure a uniform distribution of the heat field during heat treatment and effectively reduce heat loss.

[0029] In one embodiment of the present invention, the other end of the ultrasonic amplitude transformer is connected to the transducer. A cooling medium connecting rod is provided between the ultrasonic amplitude transformer and the transducer. The cooling medium connecting rod has a continuous cooling channel inside, through which cooling medium circulates. The constant temperature of the circulating cooling medium is 393K. The cooling medium includes water or gas. The present invention, by providing a cooling medium connecting rod between the ultrasonic amplitude transformer and the transducer, isolates the influence of the high-temperature thermal field on the transducer, ensuring that the transducer is always within a safe operating temperature range.

[0030] In one embodiment of the present invention, the connection relationship of the ultrasonic device can be as follows: the precipitation-strengthened nickel-based superalloy is rigidly connected to the working section of the ultrasonic amplitude transformer; one end of the ultrasonic amplitude transformer away from the precipitation-strengthened nickel-based superalloy is connected to one end of the cooling medium connecting rod; and the other end of the cooling medium connecting rod is connected to the transducer. The transducer of the present invention is used to convert electrical energy from the generator into mechanical energy of the same frequency.

[0031] In one embodiment of the present invention, the precipitation-strengthened nickel-based superalloy is fed into the homogenization zone of a heat treatment device (such as a muffle furnace, specifically a vertical muffle furnace) using a clamp. Specifically, the precipitation-strengthened nickel-based superalloy is vertically placed into the heat treatment device (such as a muffle furnace, specifically a vertical muffle furnace) through a through hole in the furnace cover using a clamp. The upper end of the ultrasonic amplitude transformer is fastened to the furnace cover through a clamping structure to ensure that the precipitation-strengthened nickel-based superalloy is located at the geometric center of the furnace chamber, thereby ensuring the mechanical stability of the system.

[0032] This invention describes an ultrasonic solution treatment of precipitation-strengthened nickel-based superalloys within an ultrasonic and thermal field. The ultrasonic solution treatment includes a heating stage, a holding stage, and a cooling stage. In one embodiment of this invention, the heating stage is conducted in an inert gas environment, specifically high-purity argon. Throughout the heat treatment process, an inert gas is continuously introduced into the furnace at a stable flow rate to prevent oxidation of the precipitation-strengthened nickel-based superalloy at high temperatures.

[0033] In one embodiment of the present invention, the heating stage includes a first heating stage and a second heating stage; the first heating stage includes heating from room temperature to 1470~1490K, specifically 1483K; the heating rate of the first heating stage is 5~10K / min, specifically 5K / min, 8K / min or 10K / min, and the holding time after heating to 1470~1490K is 1~2 hours; the second heating stage includes heating from 1470~1490K to the set temperature of the holding stage; the heating rate of the second heating stage is 5~10K / min, specifically 5K / min, 8K / min or 10K / min. The present invention, by controlling the heating rate, avoids damage to the muffle furnace due to excessively high heating rates.

[0034] The ultrasonic solution treatment described in this invention includes a heat preservation stage, wherein the set temperature of the heat preservation stage is T = T0 + T1 - T2, where T0 is the target temperature of the precipitation-strengthened nickel-based superalloy, T1 is the ultrasonic cooling compensation temperature, and T2 is the ultrasonic thermal effect inverse compensation temperature; the target temperature T0 of the precipitation-strengthened nickel-based superalloy is 1350~1550K, specifically 1533K; the ultrasonic cooling compensation temperature T1 = α·h·S·R(T0 - T2) / T1 s ), where α is the proportionality coefficient, h is the convective heat transfer coefficient, S is the heat transfer area, R is the equivalent thermal resistance of the ultrasonic conduction component, and T s Temperature of the cooling medium; The ultrasonic thermal effect countercompensation temperature T2= Where E is the Young's modulus of the precipitation-strengthened nickel-based superalloy, tanδ is the loss factor of the precipitation-strengthened nickel-based superalloy, k is the thermal conductivity of the precipitation-strengthened nickel-based superalloy, L is the length of the cylindrical precipitation-strengthened nickel-based superalloy along the vibration direction, S0 is the cross-sectional area of ​​the cylindrical precipitation-strengthened nickel-based superalloy, f0 is the ultrasonic frequency of the ultrasonic field, and A is the amplitude of the ultrasonic field.

[0035] This invention applies an ultrasonic field during the heat preservation stage. In one embodiment, the ultrasonic field is applied 0-2 hours after the start of the heat preservation stage. The ultrasonic frequency f0 of the ultrasonic field satisfies 15kHz ≤ f0 ≤ 25kHz. By controlling the ultrasonic frequency f0 and the ultrasonic amplitude A, the ultrasonic vibration is amplified by a variable amplitude rod and introduced into the alloy sample at high temperature, achieving synergistic treatment of the alloy sample by the ultrasonic field and the thermal field.

[0036] The ultrasonic frequency described in this invention is dynamically adjusted by an automatic frequency tracking system. The system scans within the range of 15 to 25 kHz, searches for and locks in real time at the natural frequency of the vibrating assembly consisting of the amplitude transformer and the sample, so as to ensure the resonance state and efficient energy transmission during the ultrasonic processing.

[0037] The amplitude A of the ultrasonic field described in this invention satisfies 1 μm. , where σ y ρ and c represent the yield strength, density, and velocity of sound of the precipitation-strengthened nickel-based superalloy under the set temperature conditions during the heat preservation stage.

[0038] As one embodiment of the present invention, the yield strength σ of the precipitation-strengthened nickel-based superalloy is... y Satisfying σ y ≥Eε max Where E is the Young's modulus of precipitation-strengthened nickel-based superalloys, and ε max The maximum strain amplitude at the end face of the ultrasonic amplitude transformer satisfies ε max / A max =(D2 / D1) 1 / 2 Where D1 is the diameter of the precipitation-strengthened nickel-based superalloy, and D2 is the diameter of the ultrasonic amplitude transformer.

[0039] As one embodiment of the present invention, the present invention utilizes the target enhancement value D of the solute diffusion coefficient. us Calculate the amplitude A of the ultrasonic field. us / D0=exp[-(E a -ΔE vib ) / k B T], where ΔE vib =αA 2 f0 2 D us D0 is the diffusion coefficient of ultrasound within the alloy, E is the intrinsic pre-factor of the material, and E is the diffusion coefficient of ultrasound within the alloy. a It is the thermal activation energy, ΔE vib The reduction in activation energy caused by ultrasound, k B Let be the Boltzmann constant, T be the absolute temperature, f0 be the ultrasonic frequency, and α be the coupling coefficient related to precipitation-strengthened nickel-based superalloys. The amplitude A1 is obtained from the objective value; when A1 ≤ A... max-T Set A=A1 when the condition is met, and set A=A otherwise. max-T Process it.

[0040] In one embodiment of the present invention, the ultrasonic frequency of the ultrasonic field is 15~25kHz, specifically 15kHz, 20kHz or 25kHz; the amplitude is 1~3μm, specifically 1.5μm; and the heat preservation time after applying the ultrasonic field in the heat preservation stage is 1~3h, specifically 2h.

[0041] Depending on the purpose of heat treatment, it can be divided into solution treatment and aging treatment. This invention applies a continuous ultrasonic field of specific frequency and amplitude to precipitation-strengthened nickel-based superalloys during solution treatment, increasing the number of nucleation sites and optimizing their distribution within the superalloy system. The ultrasonic energy generates mechanical vibrations within the superalloy, significantly promoting the diffusion and rearrangement of solute atoms, effectively improving microstructure uniformity and reducing compositional segregation. The ultrasonic field lowers the nucleation barrier of the precipitated phase, promoting the formation of numerous uniform and dispersed nucleation sites. This allows the precipitated phase to solidify or undergo phase transformation at a higher nucleation rate during subsequent controlled cooling, ultimately resulting in a fine-sized, uniformly distributed, and regularly morphologically regular strengthening phase, achieving precise control over the material's microstructure and mechanical properties. Furthermore, by optimizing the synergistic effect of ultrasonic parameters and heat treatment processes, precise control over the size, distribution, and morphology of the precipitated phase is achieved, further enhancing the precipitation strengthening effect and ultimately significantly improving the alloy's strength, hardness, and high-temperature mechanical properties. This invention provides an effective and controllable new approach for the preparation of high-performance materials.

[0042] This invention applies continuous ultrasonic vibration with specific parameters to precipitation-strengthened nickel-based superalloys at high temperatures during solution treatment. The ultrasonic field effectively promotes the diffusion and rearrangement of solute atoms, reduces segregation, and achieves highly homogenized microstructure by applying mechanical action to the melt or solid microstructure. It also creates thermodynamic and kinetic conditions for the formation of numerous uniform and fine precipitate nuclei during subsequent cooling. Ultimately, the significant precipitation strengthening effect generated by these fine, dispersed strengthening phases comprehensively enhances the alloy's overall strength and plasticity at both room temperature and high temperatures. By introducing a highly efficient mechanical vibration field into the traditional heat treatment process, this invention eliminates the need for additional alloying elements or complex equipment, and avoids significantly extending processing time or increasing processing temperature. This allows for the preparation of high-performance materials while significantly reducing energy consumption and process costs, aligning with the development concept of green manufacturing.

[0043] The ultrasonic solution treatment described in this invention includes a cooling stage, during which an ultrasonic field is applied throughout. In one embodiment, the cooling stage involves cooling the set temperature of the holding stage to room temperature. This cooling is air cooling, specifically static air cooling, at a rate of 30-150 K / min. The amplitude A of the ultrasonic field applied during the cooling stage is the same as that during the holding stage. Specifically, the cooling stage process may involve stopping heating, removing the precipitation-strengthened nickel-based superalloy as a whole from the muffle furnace homogenization zone, applying the same ultrasonic field as in the holding stage to the precipitation-strengthened nickel-based superalloy, and continuing this process until the temperature monitoring of the precipitation-strengthened nickel-based superalloy shows below 323 K or confirms that it has reached room temperature. Then, the ultrasonic field is turned off to ensure the continuous regulatory effect of ultrasound on the nucleation and early growth of the precipitated phase.

[0044] As one embodiment of the present invention, the ultrasonic solution treatment is followed by an aging treatment; the aging treatment includes a first aging treatment and a second aging treatment.

[0045] In one embodiment of the present invention, the first aging treatment includes a first heating stage, a first holding stage, and a first cooling stage; the first heating stage includes heating from room temperature to 1350~1400K, specifically 1373K, at a heating rate of 5~10K / min, specifically 5K / min, 8K / min, or 10K / min; the holding time of the first holding stage is 3~5h, specifically 4h; the first cooling stage includes natural cooling in air to room temperature at a cooling rate of 30~150K / min. The second aging treatment includes a second heating stage, a second holding stage, and a second cooling stage. The second heating stage involves heating from room temperature to 1000-1200K, specifically 1143K, at a heating rate of 2-5K / min, specifically 2K / min, 3K / min, 4K / min, or 5K / min. The holding time for the second holding stage is 18-22 hours, specifically 20 hours. The second cooling stage involves natural cooling to room temperature in air. This aging treatment promotes the uniform growth and morphology correction of the precipitated phases, enabling them to reach their optimal size, and further improves the mechanical properties of the alloy.

[0046] Figure 1 This is a flowchart of an ultrasonic post-treatment method for precipitation-strengthened nickel-based superalloys with single-crystal or homogeneous polycrystalline structures, provided by the present invention. To further illustrate the present invention, the technical solutions will be clearly and completely described below in conjunction with embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0047] Example 1 The M6 ​​external thread at one end of a precision-machined cylindrical DZ125 nickel-based alloy sample is screwed into the corresponding internal thread at the end of the working section of an ultrasonic amplitude transformer made of 45 steel. A pre-prepared cylindrical mullite fiber insulation sleeve is fitted onto the outside of the working section of the ultrasonic amplitude transformer, completely covering the portion of the ultrasonic amplitude transformer located inside the muffle furnace. A cooling medium connecting rod is installed at the end of the ultrasonic amplitude transformer furthest from the working section, and the cooling medium connecting rod is connected to the transducer to obtain the sample-amplifier assembly. The sample-amplifier assembly is vertically fed into the homogenization zone of the vertical muffle furnace using a special clamp. The ultrasonic amplitude transformer is securely connected to the furnace cover through a clamping structure, positioning the alloy sample at the geometric center of the muffle furnace chamber.

[0048] After the furnace door is closed, a high-purity argon gas source is turned on to continuously introduce argon gas into the furnace chamber, and the gas flow rate is kept constant throughout the heat treatment process. A multi-stage heating program is set on the furnace control system: first, the temperature is raised from room temperature to 1483K at a rate of 10K / min, and held at this temperature for 2 hours; then, the temperature is raised from 1483K to 1533K at a rate of 5K / min, and held at this target temperature for 1 hour.

[0049] Once the temperature stabilizes at 1533K, the ultrasonic generator is started. The device automatically executes the frequency search program. After confirming that the resonance state is stable, the ultrasonic output is turned on. Continuous ultrasonic vibration with a frequency of 25kHz and an amplitude of 1.5μm is applied for ultrasonic field coupling heat treatment for 2 hours.

[0050] Stop heating, quickly open the furnace door, and use a special clamp to remove the entire sample-amplifier assembly. Cool it in still air. During the cooling process, the ultrasonic generator remains on, and the ultrasonic field continues to act on the alloy sample until the temperature monitoring of the alloy sample shows below 323K or it is confirmed that it has dropped to room temperature. Then, turn off the ultrasonic system to obtain the ultrasonically dissolved DZ125 nickel-based precipitation-strengthened alloy.

[0051] Comparative Example 1 The preparation method is basically the same as in Example 1, except that no ultrasonic field is applied during the overall heat treatment process, resulting in a heat-treated DZ125 nickel-based precipitation-strengthened alloy.

[0052] The ultrasonically dissolved DZ125 nickel-based precipitation-strengthened alloy obtained in Example 1 and the heat-treated DZ125 nickel-based precipitation-strengthened alloy obtained in Comparative Example 1 were scanned using a scanning electron microscope to obtain... Figure 2 . Figure 2 These are comparative images showing the microstructure of the DZ125 nickel-based precipitation-strengthened alloy in Example 1 and Comparative Example 1. Figure 2This indicates that, after ultrasonic field coupling heat treatment, the DZ125 nickel-based precipitation-strengthened alloy in Example 1 exhibits more uniform solute diffusion, a smaller MC carbide phase size, and a significantly increased nucleation density of the γ' precipitate phase.

[0053] Example 2 The ultrasonically dissolved DZ125 nickel-based precipitation-strengthened alloy obtained in Example 1 was subjected to non-ultrasonic aging treatment in a muffle furnace. The temperature was increased to 1373K at a rate of 10K / min and heat-treated for 4 hours. After cooling to room temperature in air, the temperature was increased to 1143K at a rate of 3K / min and heat-treated for 20 hours. After cooling to room temperature in air, the regulated DZ125 nickel-based precipitation-strengthened alloy was obtained.

[0054] Comparative Example 2 The heat-treated DZ125 nickel-based precipitation-strengthened alloy obtained in Comparative Example 1 was subjected to non-ultrasonic aging in a muffle furnace. The temperature was increased to 1373 K at a rate of 10 K / min and heat-treated for 4 h. After cooling to room temperature in air, the temperature was increased to 1143 K at a rate of 3 K / min and heat-treated for 20 h. After cooling to room temperature in air, the regulated DZ125 nickel-based precipitation-strengthened alloy was obtained.

[0055] Figure 3 The images show a comparison of the microstructures of the DZ125 nickel-based precipitation-strengthened alloys in Example 2 and Comparative Example 2. Figure 3 The metallographic structure comparison diagrams shown indicate that when the DZ125 nickel-based precipitation-strengthened alloy, after ultrasonic field coupling heat treatment and ultrasonic solution treatment, undergoes another heat treatment, the size of the γ' precipitate in the resulting controlled DZ125 nickel-based precipitation-strengthened alloy is significantly refined, and the uniformity of its distribution is greatly improved.

[0056] Test Example 1 The modified DZ125 nickel-based precipitation-strengthened alloys obtained in Example 2 and Comparative Example 2 were tested for tensile properties at 298K and 1033K, respectively. The tensile specimens were made from DZ125 nickel-based precipitation-strengthened alloy, machined into rod-shaped specimens with a diameter of 3mm and a gauge length of 16.5mm. Before the test, the real-time temperature was measured by thermocouples. After heating to the specified temperature, the specimens were held at that temperature for 3 minutes, and then subjected to a 10... -3 s -1 The strain rate was stretched until fracture, and the stress-strain curve was obtained. The test results are as follows: Figure 4 As shown. Figure 4 This is a comparison chart of the tensile properties of the DZ125 nickel-based precipitation-strengthened alloys in Example 2 and Comparative Example 2. According to... Figure 4It can be seen that the optimization of the microstructure of the DZ125 nickel-based precipitation-strengthened alloy after regulation in Example 2 directly translates into a significant improvement in mechanical properties: at 298K, the tensile strength of the regulated DZ125 nickel-based precipitation-strengthened alloy increased by 1.3 times and the maximum elongation increased by 1.2 times; at a high temperature of 1033K, the tensile strength and elongation of the regulated DZ125 nickel-based precipitation-strengthened alloy also increased by 1.1 times simultaneously.

[0057] This invention applies continuous ultrasonic vibration with specific parameters to an alloy sample at high temperature during the solution treatment and heat holding stage of the heat treatment process. This ultrasonic field effectively promotes the diffusion and rearrangement of solute atoms by applying mechanical action to the melt or solid structure, reduces segregation, achieves high homogenization of the structure, and creates thermodynamic and kinetic conditions for the formation of a large number of uniform and fine precipitate nuclei during the subsequent cooling process. Finally, with the help of the significant precipitation strengthening effect generated by these fine and dispersed strengthening phases, the overall strength and plasticity of the alloy are comprehensively improved at room temperature and high temperature.

[0058] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. An ultrasonic post-processing method for single-crystal or uniform columnar polycrystalline nickel-based superalloys, comprising the following steps: In an ultrasonic field and a thermal field, a precipitation-strengthened nickel-based superalloy is subjected to ultrasonic solution treatment, wherein the as-cast microstructure of the precipitation-strengthened nickel-based superalloy is a single crystal or a uniform columnar polycrystalline structure; the ultrasonic solution treatment includes a heating stage, a holding stage and a cooling stage, wherein an ultrasonic field is applied in the holding stage and the cooling stage. The set temperature of the heat preservation stage is T=T0+T1-T2, where T0 is the target temperature of precipitation-strengthened nickel-based superalloy, T1 is the ultrasonic cooling compensation temperature, and T2 is the ultrasonic thermal effect reverse compensation temperature. During the ultrasonic solution treatment, the ultrasonic frequency f0 of the ultrasonic field satisfies 15kHz ≤ f0 ≤ 25kHz, and the amplitude A satisfies 1μm. , where σ y ρ and c represent the yield strength, density, and velocity of sound of the precipitation-strengthened nickel-based superalloy under the set temperature conditions during the heat preservation stage.

2. The ultrasonic post-processing method according to claim 1, characterized in that, The ultrasonic field is achieved by a rigid connection between an ultrasonic amplitude transformer and a precipitation-strengthened nickel-based high-temperature alloy. The ultrasonic amplitude transformer is made of a high-temperature, high-strength alloy. The rigid connection includes a threaded connection or a clamping connection.

3. The ultrasonic post-processing method according to claim 1, characterized in that, The target temperature T0 of the precipitation-strengthened nickel-based superalloy is 1350~1550K, and the ultrasonic cooling compensation temperature T1 = α·h·S·R(T0-T s ), where α is the proportionality coefficient, h is the convective heat transfer coefficient, S is the heat transfer area, R is the equivalent thermal resistance of the ultrasonic amplitude transformer, and T s Temperature of the cooling medium; The ultrasonic thermal effect countercompensation temperature T2= Where E is the Young's modulus of the precipitation-strengthened nickel-based superalloy, tanδ is the loss factor of the precipitation-strengthened nickel-based superalloy, k is the thermal conductivity of the precipitation-strengthened nickel-based superalloy, L is the length of the cylindrical precipitation-strengthened nickel-based superalloy along the vibration direction, S0 is the cross-sectional area of ​​the cylindrical precipitation-strengthened nickel-based superalloy, f0 is the ultrasonic frequency of the ultrasonic field, and A is the amplitude of the ultrasonic field.

4. The ultrasonic post-processing method according to claim 1, characterized in that, The amplitude A of the ultrasonic field is 1~3μm; the yield strength σ of the precipitation-strengthened nickel-based superalloy under the set temperature conditions during the heat preservation stage. y Satisfying σ y ≥Eε max Where E is the Young's modulus of precipitation-strengthened nickel-based superalloys, and ε max ε is the maximum strain amplitude at the end face of the ultrasonic amplitude transformer. max Satisfying ε max / A max =(D2 / D1) 1 / 2 Where D1 is the diameter of the precipitation-strengthened nickel-based superalloy, and D2 is the diameter of the ultrasonic amplitude transformer.

5. The ultrasonic post-processing method according to claim 1, characterized in that, The ultrasonic field is applied during the heat preservation stage 0-2 hours after the start of the heat preservation stage; the heat preservation time after the ultrasonic field is applied during the heat preservation stage is 1-3 hours.

6. The ultrasonic post-processing method according to claim 1, characterized in that, The heating phase is carried out in an inert gas and includes a first heating phase and a second heating phase; the first heating phase includes heating from room temperature to 1470~1490K, and the second heating phase includes heating from 1470~1490K to the set temperature of the heat preservation phase.

7. The ultrasonic post-processing method according to claim 6, characterized in that, The heating rate in the first heating stage is 5~10K / min, and the holding time after heating to 1470~1490K is 1~2h; the heating rate in the second heating stage is 5~10K / min.

8. The ultrasonic post-processing method according to claim 1, characterized in that, The cooling stage involves cooling the set temperature of the heat preservation stage to room temperature. The cooling is performed by air cooling at a rate of 30-150 K / min. An ultrasonic field is applied throughout the cooling stage, and the amplitude A of the ultrasonic field applied during the cooling stage is the same as that during the heat preservation stage.

9. The ultrasonic post-processing method according to claim 1, characterized in that, The ultrasonic solution treatment is followed by an aging treatment.

10. The ultrasonic post-processing method according to claim 9, characterized in that, The timeliness processing includes a first timeliness processing and a second timeliness processing; The first aging treatment includes a first heating stage, a first holding stage, and a first cooling stage; the first heating stage includes heating from room temperature to 1350~1400K at a heating rate of 5~10K / min, the holding time of the first holding stage is 3~5h, and the first cooling stage includes natural cooling in air to room temperature at a cooling rate of 30~150K / min. The second aging treatment includes a second heating stage, a second holding stage, and a second cooling stage. The second heating stage includes heating from room temperature to 1000~1200K at a heating rate of 2~5K / min. The holding time of the second holding stage is 18~22h. The second cooling stage includes natural cooling to room temperature in air.

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