A method and system for synergistically regulating helium bubbles and dislocation loops in nickel-based alloys based on limited high-density pulse current

Abstract

This invention discloses a method and system for synergistic control of helium bubbles and dislocation loops in nickel-based alloys based on a finite number of high-density pulsed currents. The method utilizes high-density pulsed currents to generate localized, instantaneous Joule thermal shocks around nanoscale helium bubbles, causing a sudden increase in internal pressure and forcing helium atoms to be emitted into the matrix, thereby inducing helium bubble dissociation. Simultaneously, the high-density electrons of the pulsed current excite dislocation core atoms, thus activating dislocation line slip. During this slip, the dislocation line absorbs and drags the irradiated dislocation loops to inherent defect traps in the material, where they are annihilated, thereby reducing the density and size of the dislocation loops. Both mechanisms occur synergistically under the same pulsed current. Compared with existing technologies, the method of this invention has the following advantages: significantly reduced helium bubbles with no thermal growth; significantly reduced dislocation loops; controllable alloy temperature allowing operation in atmospheric environments without inert gas protection; extremely low energy consumption and short processing time; extremely simple process, easy to automate; and strong universality.

Description

Technical Field

[0001] This invention relates to the field of radiation damage repair technology for nuclear reactor structural materials, and in particular to a method and system for synergistic control of nickel-based alloy helium bubbles and dislocation loops based on a finite number of high-density pulse currents. Background Technology

[0002] Nickel-based superalloys are core materials for critical components of nuclear reactors, such as in-core structures. Under long-term high-flux neutron irradiation, two main types of nanoscale defects develop within the alloy: 1) helium bubbles (formed by the aggregation of helium atoms generated from (n, α) reactions); and 2) dislocation loops (generated by cascade collisions). These defects lead to irradiation hardening, embrittlement, and swelling of the material, seriously threatening reactor safety.

[0003] Currently, the main repair technologies for irradiation damage to in-service components include: 1. Overall annealing: This method eliminates defects by heating at high temperatures for an extended period (usually several hours). However, it has significant drawbacks: a) It requires prolonged reactor shutdown, resulting in substantial economic losses; b) High temperatures can induce Ostwald ripening (coarsening) and dislocation loop growth in helium bubbles, potentially worsening material properties; c) Traditional annealing has limited effectiveness in eliminating deep helium bubbles within components.

[0004] 2. The published patent application CN115148384A (Method for Restoring Irradiation Damage to Nuclear Reactor Pressure Vessels Using Pulsed Current) describes a method that repairs dislocation loop defects in the steel of nuclear reactor pressure vessels using pulsed current. Its core technology utilizes the Joule heating effect of the pulsed current to heat the material to a high temperature (argon gas protection was explicitly used in the pulsed current treatment in the embodiments to prevent oxidation, indicating that the process temperature is significantly higher than room temperature; the literature Journal of Materials Science & Technology 194 (2024) 247–262 explicitly states that the process temperature is 450℃), thereby promoting the elimination of dislocation loops. However, this method has the following fundamental flaws: (a) It only considers dislocation loops and completely ignores helium bubbles. In practical engineering, neutron irradiation inevitably produces both helium bubbles and dislocation loops simultaneously. If only dislocation loops are repaired while helium bubbles are ignored, the helium bubbles will still cause material embrittlement and swelling. (b) The high-temperature environment created by the pulsed current leads to thermal growth of helium bubbles. For materials containing helium bubbles (such as nickel-based alloys), high-temperature treatment accelerates the Ostwald ripening or migration and merging of helium bubbles, causing the helium bubble size to increase, the density to increase or decrease only slightly, and even exacerbating the deterioration of material properties. Therefore, the method of this patent is completely unsuitable for the repair of irradiation damage containing helium bubbles. (c) Inert gas protection is required. To prevent oxidation at high temperatures, operation must be carried out under vacuum or inert gas protection, which makes in-situ repair difficult for large in-service components (such as reactor pressure vessels). (d) The pulse current parameters are long-term continuous or multiple pulses (the processing times in the examples are 240 minutes, 30 minutes, and 5 minutes, respectively), resulting in a significant macroscopic temperature rise, making it impossible to avoid the thermal growth of helium bubbles. CN115148384A only targets dislocation loops in pressure vessel steel, using the macroscopic thermal effect of pulse current (requiring high-temperature excitation, thus requiring argon protection) to promote the elimination of dislocation loops, but it does not involve helium bubbles at all. Its high-temperature environment will cause helium bubbles to undergo Ostwald ripening and grow, even deteriorating material properties, and requires inert gas protection, making in-situ operation impossible in an open environment.

[0005] 3. Patent application CN121759850A (Repair Method and System for Irradiated Bubble Defects, Electronic Equipment and Storage Medium) has been published. The repair method described includes a three-stage synergistic process: pulsed current activation → ultrasonic stress field guidance → laser shock compression. Its shortcomings are: (a) The process is complex, requiring the sequential coordination of electrical, acoustic, and optical equipment, placing high demands on equipment and operational difficulty, making it difficult to implement in situ within the confined, high-radiation environment of a nuclear reactor; (b) It does not reveal the elimination mechanism for dislocation loops, particularly lacking effective repair methods for stable Frank loops; (c) Laser shock may introduce a surface heat-affected zone and residual tensile stress; (d) The pulsed current parameters used in the activation stage do not clearly limit the number of pulses, potentially leading to macroscopic heat accumulation. CN121759850A employs a three-stage sequential synergistic process: pulsed current activation → ultrasonic stress field guidance → laser shock compression. This process requires the timing control of three sets of electrical, acoustic, and optical equipment, making it complex. Furthermore, the laser shock and ultrasonic coupling have poor in-situ adaptability to narrow, high-radiation environments and do not involve the elimination of dislocation loops.

[0006] In summary, there is an urgent need to develop a repair method that is simple to implement, can be operated in situ, can simultaneously and efficiently reduce the density and size of helium bubbles and dislocation rings in nickel-based alloys, and avoids the thermal growth of helium bubbles caused by high temperatures. Summary of the Invention

[0007] The purpose of this invention is to overcome the defects of the prior art, especially the problems of thermal growth of helium bubbles and the need for inert gas protection due to the requirement of high temperature, and to provide a method and system for the coordinated control of nickel-based alloy helium bubbles and dislocation loops based on a finite number of high-density pulse currents.

[0008] The method of this invention utilizes high-density pulsed current (peak current density > 170 A / mm²). 2 A localized, transient Joule thermal shock (rather than macroscopic overall heating) is generated around the nanoscale helium bubble, causing the internal pressure of the helium bubble to surge to over 20 GPa. This forces helium atoms within the bubble to be emitted into the matrix, thereby inducing helium bubble dissociation. Simultaneously, the electronic excitation of the same pulsed current lowers the Peierls barrier for dislocation initiation, activating dislocation line slip. During its movement, the slipping dislocation line absorbs and drags the irradiated dislocation loop, sweeping it away from its original position, thus reducing the density and size of the dislocation loop. Both mechanisms occur synergistically under the influence of the same pulsed current.

[0009] The objective of this invention can be achieved through the following technical solutions: The first objective of this invention is to provide a method for the synergistic control of helium bubbles and dislocation loops in nickel-based alloys based on a finite number of high-density pulsed currents. This method is used to repair helium bubbles and dislocation loops in regions containing irradiation damage, and includes the following steps: S1. Sample preparation and system connection (atmospheric environment, no inert gas protection required): In an atmospheric environment, the pulse power module is connected to the electrode module, which then forms a contact connection with the area to be repaired of the irradiated nickel-based alloy component. The nanoscale defects generated within the irradiated nickel-based alloy component include helium bubbles and dislocation loops. No vacuum chamber or inert gas protection is required because the macroscopic heat accumulation of the material during the repair process is low (surface temperature ≤110℃) and short (milliseconds), preventing significant oxidation.

[0010] S2. Preset parameters for a limited number of high-density pulses and start temperature monitoring: Based on the degree of irradiation damage to the nickel-based alloy component containing irradiation damage, the controller presets pulse parameters, including the number of pulses. The pulse power supply is set to a limited output mode, and the preset number of pulses is 1 ≤ N ≤ 10. This is a key measure to control macroscopic heat accumulation and avoid the thermal growth of helium bubbles. The temperature monitoring module is activated to collect the surface temperature data of the area to be repaired in real time to ensure that the component temperature never exceeds 110°C.

[0011] S3. Applying a finite number of high-density pulsed currents to synergistically control helium bubbles and dislocation loops under low-heat accumulation conditions: The controller controls the pulse power supply module to apply a set of high-density pulsed currents to the area to be repaired according to a preset number of pulses N, in order to achieve coordinated control of the nickel-based alloy helium bubble and dislocation loop. Due to the use of high-density, narrow-width (≤1ms), and finite-number (N ≤ 10) pulse parameters, the total energizing time of the alloy is N × pulse width, typically in the millisecond range. Macroscopic Joule heating effects are strictly limited, and the surface temperature of the area to be repaired is ≤110℃ (low heat accumulation). Throughout the pulsed current application process, the temperature monitoring module provides real-time feedback on the surface temperature of the area to be repaired. If the surface temperature of the area to be repaired reaches 90% of the threshold of 110℃, the controller pauses output. After the temperature drops to room temperature, the pulsed current is applied again until N pulses are completed. S4. Stop pulsed current and allow natural cooling: After the preset number of pulses N is completed, the controller shuts down the pulse power module and stops applying pulse current, allowing the area to be repaired to cool naturally to room temperature without external energy input (since the temperature rise itself is very low, the cooling time is extremely short), thus completing the repair of the helium bubble and dislocation loop in the area to be repaired.

[0012] Furthermore, in step S1, the nickel-based alloy component containing irradiation damage can be a Ni-Mo-Cr alloy, etc.

[0013] Furthermore, in step S2, the pulse parameters also include peak current density, pulse width, pulse frequency, and pulse waveform.

[0014] Furthermore, the peak current density is set to 171~200 A / mm². 2 The pulse width is 800~1000 μs; the pulse frequency is 80~120 Hz; and the pulse waveform is a square wave.

[0015] More preferably, the peak current density is set to 177 A / mm². 2 (High density ensures local Joule thermal shock and electron wind effect).

[0016] More preferably, the pulse width is 1000μs (narrow pulse width, short single energy input time).

[0017] More preferably, the pulse frequency is 100 Hz.

[0018] More preferably, the pulse waveform is a square wave.

[0019] Further, in step S2, the degree of irradiation damage of the nickel-based alloy component containing irradiation damage includes the initial density of the helium bubble, the average size of the helium bubble, the initial density of the dislocation loop, and the average size of the dislocation loop.

[0020] Furthermore, in step S2, in order to achieve the desired effect based on the degree of irradiation damage of the nickel-based alloy component containing irradiation damage, the controller presets pulse parameters to maximize the current density passing through the nickel-based alloy component containing irradiation damage while minimizing the temperature rise of the component. Specifically, different parameters are used to test and process control samples to determine the pulse parameters to be used.

[0021] Furthermore, in step S3, the synergistic regulation of the nickel-based alloy helium bubble and dislocation loop includes the synergistic excitation of the helium bubble reduction mechanism and the dislocation loop reduction mechanism.

[0022] Furthermore, in step S3, under low heat accumulation conditions, the high-density pulsed current synergistically (i.e., the two mechanisms occur simultaneously, are independent of each other, and work together) stimulates the following two regulatory mechanisms: a) Helium bubble reduction mechanism (high-density current-induced dissociation): A high-density pulsed current generates a localized, instantaneous Joule thermal shock (rather than macroscopic overall heating) around a nanoscale helium bubble. Due to the resistivity difference between the helium bubble and the substrate, the current accumulates around the helium bubble, causing the internal pressure to surge to over 20 GPa. This forces helium atoms to be emitted from the bubble into the substrate, resulting in bubble shrinkage or partial dissociation, thereby reducing the bubble's density and average size. Since the macroscopic temperature is ≤110℃, Ostwald ripening or migration and merging of the helium bubble will not be triggered. This is a fundamental difference from high-temperature processes: high temperatures cause helium bubbles to grow, while the low-heat accumulation conditions of this invention ensure that helium bubbles can only shrink and not grow.

[0023] b) Dislocation Loop Reduction Mechanism (High-Density Electron-Activated Dislocation Slip Sweep): A high-energy electron flow from the same high-density pulsed current acts on the dislocation core atom, generating an electronic excitation effect. This lowers the Peierls barrier for dislocation initiation, activating previously pinned dislocation lines to begin slipping. During their movement, these activated slip dislocation lines encounter surrounding irradiated dislocation loops (especially difficult-to-move Frank loops). Through absorption, dragging, and other mechanisms, the slip dislocation lines sweep the dislocation loops from their original positions. Some dislocation loops are transported to intrinsically defective traps such as grain boundaries for annihilation, thereby reducing the density and average size of dislocation loops. This mechanism requires no high-temperature assistance and is purely driven by high-density electrons, thus it can be effectively implemented under low-heat accumulation conditions.

[0024] The two mechanisms described above work together to regulate the helium bubble and dislocation loop under the same set of limited high-density pulsed currents. Throughout the pulsed current application process, the temperature monitoring module provides real-time feedback on the surface temperature. Due to the limited number of pulses and the extremely short single-pulse energy input time, the macroscopic surface temperature never exceeds 110°C.

[0025] Furthermore, in step S4, during the process of allowing the area to be repaired to cool naturally to room temperature, the helium atoms and vacancies released from the helium bubble, as well as the point defects generated by the dislocation loops that have been swept away, further diffuse to the inherent defect traps such as grain boundaries and surfaces and annihilate, thus completing the repair of the helium bubble and dislocation loops in the area to be repaired.

[0026] Furthermore, compared to the untreated state, after the helium bubbles and dislocation loops in the region to be repaired are repaired, the helium bubble density decreases, the average size of the helium bubbles decreases, the dislocation loop density decreases, and the average size of the dislocation loops decreases.

[0027] Furthermore, the method of the present invention described above has the following beneficial effects: helium bubbles are significantly reduced and thermal growth is eliminated; dislocation loops are significantly reduced; it can operate in an atmospheric environment without the need for inert gas protection; energy consumption is extremely low and time is extremely short; the process is extremely simple and easy to automate; and it has strong universality.

[0028] The second objective of this invention is to provide a system for repairing irradiation damage to nickel-based alloys using pulsed current, for realizing the aforementioned method for synergistic control of helium bubbles and dislocation loops in nickel-based alloys based on a finite number of high-density pulsed currents, the system comprising: A pulsed power supply module for applying pulsed current to the area to be repaired of a nickel-based alloy component containing radiation damage; The electrode module, connected to the pulse power supply module, forms electrical contact with the area to be repaired of the nickel-based alloy component containing radiation damage; The temperature monitoring module is used to monitor the surface temperature of the area to be repaired of the nickel-based alloy component containing irradiation damage in real time, and to provide feedback to the controller to ensure that the macroscopic temperature does not exceed 110°C during the repair process. The controller is connected to the pulse power supply module and the temperature monitoring module to control the pulse current output of the pulse power supply module according to preset pulse parameters (including preset pulse number, peak current density, pulse width, pulse frequency, pulse waveform, etc.) and dynamically adjust according to feedback from the temperature monitoring module.

[0029] Furthermore, the pulse power module has a counting mode output function, which can output high-density pulse current according to a preset number of pulses (N), rather than continuous output.

[0030] Furthermore, the electrode module includes a pair of output electrodes; the pair of output electrodes form an electrical contact connection with the area to be repaired of the nickel-based alloy component containing irradiation damage, and can be used directly in an atmospheric environment without the need for a vacuum chamber or inert gas protection.

[0031] Furthermore, the temperature monitoring module includes an infrared thermal imager.

[0032] The technical concept of this invention includes: By limiting the number of pulsed current applications to a finite number (N ≤ 10 times) and using a narrow pulse width, the total energizing time is controlled at the millisecond level, thereby strictly limiting macroscopic heat accumulation to a low level (surface temperature ≤ 110℃). This "finite number" method fundamentally avoids the macroscopic temperature rise caused by prolonged continuous energizing, thus preventing the thermal growth of helium bubbles (i.e., preventing Ostwald curing or migration and merging), allowing helium bubbles to be effectively reduced rather than grown. Simultaneously, due to the low macroscopic temperature rise and short duration, the material does not undergo significant oxidation, allowing for in-situ repair of in-service components directly in an atmospheric environment without any inert gas protection.

[0033] Compared with the prior art, the present invention has the following beneficial effects: 1) This invention provides a method and system for the synergistic control of helium bubbles and dislocation loops in nickel-based alloys based on a finite number of high-density pulsed currents. Using helium bubbles and dislocation loops in nickel-based alloys as the common control targets, a finite number (≤10 times) of high-density pulsed currents are employed, controlling the total energizing time to the millisecond level, with a macroscopic surface temperature ≤110℃. Under these conditions, the high-density current generates localized Joule thermal shock (pressure surge >20 GPa) around the helium bubble, reducing its dissociation. Simultaneously, high-density electrons activate dislocation slip to sweep away dislocation loops, with both occurring synergistically. This invention completely avoids the thermal growth of helium bubbles and can be operated directly in an atmospheric environment without the need for inert gas protection, achieving truly in-situ irradiation damage control.

[0034] 2) This invention provides a method and system for the coordinated control of helium bubbles and dislocation loops in nickel-based alloys based on a finite number of high-density pulsed currents. It relies solely on a single physical field—a finite number of high-density pulsed currents—to simultaneously excite both helium bubble dissociation and dislocation loop removal mechanisms within the same set of pulses, without the need for ultrasonic or laser assistance. By limiting the number of pulses to less than 10, low heat accumulation (temperature ≤110℃) is achieved, avoiding the thermal effects and residual stress that may be introduced by laser shock. The equipment of this invention is extremely simple and easy to operate, completing control within milliseconds, significantly reducing the difficulty and cost of engineering implementation, and is more suitable for in-situ repair of in-service components in the complex environment of nuclear reactors.

[0035] 3) This invention provides a method and system for the coordinated control of helium bubbles and dislocation loops in nickel-based alloys based on a finite number of high-density pulse currents. It is a finite number of high-density pulse current coordinated control method. Unlike long-term continuous or multiple pulses (such as the processing time of 240 minutes, 30 minutes, and 5 minutes in CN115148384A), this invention limits the number of pulses to less than 10 times and the total energization time to the millisecond level, which fundamentally avoids macroscopic heat accumulation and provides a premise for simultaneously reducing helium bubbles and dislocation loops.

[0036] 4) This invention provides a method and system for the synergistic control of helium bubbles and dislocation loops in nickel-based alloys based on a finite number of high-density pulsed currents. It reveals a dual mechanism by which high-density pulsed currents simultaneously reduce both helium bubbles and dislocation loops under low-heat accumulation conditions: Verification through multi-scale simulations (finite element method + molecular dynamics (MD)) shows that the high-density pulsed current, on the one hand, generates localized Joule thermal shocks around the helium bubble (pressure surges to over 20 GPa), promoting helium bubble dissociation; on the other hand, it activates dislocation slip to eliminate dislocation loops through electron wind. Both occur synergistically within the same physical field, without requiring a specific order.

[0037] 5) This invention provides a method and system for the coordinated control of nickel-based alloy helium bubbles and dislocation loops based on a finite number of high-density pulse currents. It can realize in-situ operation in an atmospheric environment without the need for inert gas protection. Since the macroscopic temperature is ≤110℃, the material does not undergo significant oxidation. Therefore, no vacuum or inert gas protection is required, and in-situ repair can be performed directly on large in-service components.

[0038] 6) This invention provides a method and system for the coordinated control of helium bubbles and dislocation loops in nickel-based alloys based on a finite number of high-density pulse currents. This method can completely avoid the thermal growth of helium bubbles. By using a finite number of pulse currents, the macroscopic temperature is controlled below 110°C, so that the helium bubbles can only dissociate and decrease without undergoing Ostwald ripening or migration and merging. This is a fundamental difference from high-temperature processes (such as CN115148384A): high-temperature processes cause helium bubble growth and are completely unsuitable for materials containing helium bubbles. Attached Figure Description

[0039] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein: Figure 1 The diagram shows the system structure for repairing irradiation damage to nickel-based alloys using pulsed current in Embodiment 1 of the present invention, as well as the monitoring of the alloy surface temperature. (a) System structure diagram, (b) Changes in alloy surface temperature during pulsed current treatment, (c) Temperature distribution of the alloy surface before current treatment, (d) Temperature distribution of the alloy surface during the first pulse treatment, (e) Temperature distribution of the alloy surface during the second pulse treatment, (f) Temperature distribution of the alloy surface during the third pulse treatment, (g) Temperature distribution of the alloy surface during the fourth pulse treatment, and (h) Temperature distribution of the alloy surface during the fifth pulse treatment.

[0040] Figure 2 The diagram shows the current distribution around a helium bubble simulated using the finite element method in Embodiment 1 of the present invention. (a) shows the current distribution in the region containing three helium bubbles at z=0, (b) shows the equivalent current density at y=0, with the same current density scale as in (a), and (c) shows the current density distribution along the marked line in (b).

[0041] Figure 3This is a schematic diagram of the molecular dynamics simulation results of helium bubble evolution under the pulsed current-induced high-density electronic excitation effect in Example 1 of the present invention. (a) The three-dimensional morphology of the helium bubble with an initial radius of 1 nanometer containing 380 vacancies and 228 helium atoms. During the pulsed current treatment, the morphology, temperature distribution and internal pressure of the helium bubble at different times are: (b) 0.2 ps, (c) 0.6 ps, (d) 1.0 ps, ​​(e) 2.0 ps, ​​(f) 25 ps, (g) Enlarged view of the helium-vacancy cluster in the marked rectangular area in Figure f, and (h) Temperature change of the matrix during the pulsed current treatment.

[0042] Figure 4 This is a schematic diagram of the molecular dynamics simulation results of pulsed current activating dislocation slip sweeping to eliminate different types of dislocation loops in Embodiment 1 of the present invention, wherein (a) dislocations bypass 1 / 3 Dislocation loop, (b) dislocation completely removes 1 / 3 Dislocation sweep 1 / 3 There are two possible outcomes for dislocation loops: (c) the dislocation loop is completely removed, and (d) some atoms of the dislocation loop are removed.

[0043] Figure 5 This is a comparison diagram of the helium bubble size distribution in the nickel-based alloy before and after the treatment of this invention.

[0044] Figure 6 This is a comparison diagram of the size distribution of dislocation rings in nickel-based alloys before and after the treatment of this invention.

[0045] Figure 7 This is a graph showing the change in hardness of nickel-based alloy nano-indentation before and after the treatment according to the present invention. Detailed Implementation

[0046] The present invention will now be described in detail with reference to specific embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. Component models, material names, connection structures, control methods, and other features not explicitly stated in this technical solution are considered to be common technical features disclosed in the prior art.

[0047] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Terms such as "upper," "lower," "left," and "right" are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may change. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0048] It should be noted that in this invention, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0049] This invention discloses a method and system for synergistic control of helium bubbles and dislocation loops in nickel-based alloys based on a finite number of high-density pulsed currents. The method utilizes high-density pulsed currents to generate localized, instantaneous Joule thermal shocks around nanoscale helium bubbles, causing a sudden increase in internal pressure and forcing helium atoms to be emitted into the matrix, thereby inducing helium bubble dissociation. Simultaneously, the high-density electrons of the pulsed current excite dislocation core atoms, thus activating dislocation line slip. During this slip, the dislocation line absorbs and drags the irradiated dislocation loops to inherent defect traps in the material, where they are annihilated, thereby reducing the density and size of the dislocation loops. Both mechanisms occur synergistically under the same pulsed current. Compared with existing technologies, the method of this invention has the following advantages: significantly reduced helium bubbles with no thermal growth; significantly reduced dislocation loops; controllable alloy temperature rise, enabling operation in atmospheric environments without inert gas protection; extremely low energy consumption and short processing time; extremely simple process, easy to automate; and strong universality.

[0050] The embodiments of the present invention are described in detail below. These embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operation processes. However, the scope of protection of the present invention is not limited to the following embodiments.

[0051] In the examples below, unless otherwise specified, the reagents used are commercially available products and the methods employed are those known in the art.

[0052] In this embodiment, the pulse power supply module includes a pulse power supply, specifically the intelligent pulse power supply from Zibo Changtai Electric Co., Ltd., model: CTNP1621-20 / 1000FN, with specific parameters: maximum output power 20kW, maximum output current 1000A, and maximum average output current 300A.

[0053] Example 1 like Figure 1As shown in (a), this embodiment provides a system for repairing irradiation damage to nickel-based alloys using pulsed current. The system includes: The pulse power supply module is used to supply power to the device containing radiation damage (helium irradiation dose of 2×10⁻⁶). 15 / cm 2 A pulse current is applied to the area to be repaired of the nickel-based alloy component. The pulse power supply module has a counting mode output function, which can output high-density pulse current according to a preset number of pulses (N), rather than continuous output. An electrode module, connected to a pulse power supply module, forms an electrical contact with the area to be repaired (6mm×3mm) of a nickel-based alloy component (10mm×3mm×1.5mm) containing irradiation damage. The electrode module includes a pair of output electrodes. The pair of output electrodes form an electrical contact connection with the area to be repaired of the nickel-based alloy component containing irradiation damage. Specifically, the two output electrodes are respectively connected to the positive and negative terminals of the pulse power supply module through wires. The two output electrodes respectively contact the two sides of the area to be repaired of the nickel-based alloy component containing irradiation damage to form an electrical contact connection. It can be used directly in an atmospheric environment without the need for a vacuum chamber or inert gas protection. In this embodiment, the output electrodes are copper electrodes. A temperature monitoring module is used to monitor the surface temperature of the area to be repaired of the nickel-based alloy component containing irradiation damage in real time, so as to provide feedback to the controller and ensure that the macroscopic temperature does not exceed 110°C during the repair process. In this embodiment, the temperature monitoring module includes an infrared thermal imager (infrared camera), which is aimed at the area to be repaired of the nickel-based alloy component containing irradiation damage. The controller (using a microcontroller) is connected to the pulse power supply module and the temperature monitoring module to control the pulse current output of the pulse power supply module according to preset pulse parameters (including preset pulse number, peak current density, pulse width, etc., as well as preset pulse frequency, pulse waveform, etc.), and dynamically adjusts it according to feedback from the temperature monitoring module.

[0054] This embodiment also provides a method for the synergistic control of helium bubbles and dislocation loops in nickel-based alloys based on a finite number of high-density pulsed currents. This method is implemented using the aforementioned system for repairing irradiation damage to nickel-based alloys with pulsed currents, and includes the following steps performed sequentially: S1. Sample preparation and system connection (atmospheric environment, no inert gas protection required): The area to be repaired of a nickel-based alloy component (Ni-Mo-Cr alloy, specifically Ni (bal.), 17.1 wt. % Mo and 7 wt. % Cr in this embodiment) containing irradiation damage is placed at the repair station (between two copper electrodes). In this embodiment, an insulator (specifically zirconia ceramic) is used to support the electrode module (including two copper electrodes). The pulse power supply module is directly connected to the electrode module in an atmospheric environment, and a pair of output electrodes of the electrode module are brought into contact with the area to be repaired of the irradiation-damaged nickel-based alloy component. The nanoscale defects generated inside the irradiation-damaged nickel-based alloy component include helium bubbles and dislocation loops. No vacuum chamber or inert gas protection is required because the macroscopic heat accumulation of the material during the repair process is low (surface temperature ≤110℃), and significant oxidation does not occur.

[0055] S2. Preset parameters for a limited number of high-density pulses and start temperature monitoring: The degree of irradiation damage to the nickel-based alloy component containing irradiation damage includes the initial density of the helium bubble, the average size of the helium bubble, the initial density of the dislocation loop, and the average size of the dislocation loop. In this embodiment, as shown... Figure 2 , 3 As shown, the initial density of helium bubbles in the irradiated nickel-based alloy component before current treatment is 18.4 × 10⁻⁶. 16 cm -3 The average size of the helium bubble is 1.3 nm, and the initial density of dislocation loops is 5.5 × 10⁻⁶. 16 cm -3 The average size of the dislocation loop is 5.5 nm. The controller presets pulse parameters, including the number of pulses. The pulse power supply is set to a finite output mode, and the preset number of pulses is 1 ≤ N ≤ 10. In this embodiment, the preset number of pulses is 5. This is a key measure to control macroscopic heat accumulation and avoid thermal growth of helium bubbles.

[0056] The pulse parameters also include peak current density, pulse width, pulse frequency, and pulse waveform.

[0057] In this embodiment, the peak current density is set to 177 A / mm². 2 (High density, ensuring localized Joule thermal shock and electron wind effects). The pulse width is 1000 μs (narrow pulse width, short single energy input time). The pulse frequency is 100 Hz. The pulse waveform is a square wave.

[0058] Simultaneously, the temperature monitoring module (in this embodiment, the infrared thermal imaging temperature monitoring module) is activated to collect surface temperature data of the area to be repaired in real time, ensuring that the temperature never exceeds 110°C.

[0059] S3. Applying a finite number of high-density pulsed currents to synergistically control helium bubbles and dislocation loops under low-heat accumulation conditions: The controller controls the pulse power supply module to apply a set of high-density pulse currents to the area to be repaired according to a preset number of pulses N, in order to achieve coordinated control of the nickel-based alloy helium bubble and dislocation loop. Due to the use of high-density, narrow-width, and finite-number (N ≤ 10) pulse parameters, the total energizing time is N × pulse width, and the total energizing time is in the millisecond range (in this embodiment, each pulse width is 1ms, the period is 10ms, the number of pulses is 5, and after each pulse is processed, there is a 20s pause before the next pulse is applied, such as...). Figure 1 As shown in b, the total energizing time in the actual alloy is 5ms, but the entire process is 100s. The macroscopic Joule heating effect is strictly limited, and the surface temperature of the area to be repaired is ≤110℃ (low heat accumulation). During the entire pulse current application process, the temperature monitoring module provides real-time feedback on the surface temperature of the area to be repaired. If the surface temperature feedback of the area to be repaired reaches 90% of the threshold of 110℃, the controller pauses the output and waits for the temperature to drop to room temperature (wait 20s) before continuing to apply the pulse current until N pulse processing is completed.

[0060] S4. Stop pulsed current and allow natural cooling: After the preset number of pulses N is completed, the controller shuts off the pulse power module and stops applying the pulse current, allowing the area to be repaired to cool naturally to room temperature without external energy input (the cooling time is extremely short due to the very low temperature rise). The helium atoms and vacancies released from the helium bubble, as well as the point defects generated by the swept dislocation loops, further diffuse to the inherent defect traps such as grain boundaries and surfaces and annihilate, completing the repair of the helium bubble and dislocation loops in the area to be repaired.

[0061] In step S2, to achieve the desired effect based on the degree of irradiation damage to the irradiated nickel-based alloy component, the controller presets pulse parameters to maximize the current density flowing through the component while minimizing its temperature rise. This requires testing with different parameters on a control sample to determine the appropriate pulse parameters. In this embodiment, the specific operation involves first testing pulse currents with different parameters within a certain range on the irradiated nickel-based alloy component to maximize the current flowing through it, while ensuring the temperature of the component does not exceed 110°C. The pulse current parameters are determined based on this principle.

[0062] In step S3, the synergistic regulation of the nickel-based alloy helium bubble and dislocation loop includes the synergistic excitation of the helium bubble reduction mechanism and the dislocation loop reduction mechanism.

[0063] Under low heat accumulation conditions, high-density pulsed current synergistically (i.e., two mechanisms occur simultaneously, are independent of each other, and work together) stimulates the following two regulatory mechanisms: a) Helium bubble reduction mechanism (high-density current-induced dissociation): A high-density pulsed current generates a localized, instantaneous Joule thermal shock (rather than macroscopic overall heating) around the nanoscale helium bubble. Due to the resistivity difference between the helium bubble and the substrate, the current accumulates around the helium bubble, causing the internal pressure to surge to over 20 GPa. This forces helium atoms to be emitted from the bubble into the substrate, causing the helium bubble to shrink or partially dissociate, thereby reducing the density and average size of the helium bubble. Because the macroscopic temperature is ≤110℃, the helium bubble will not undergo Ostwald ripening or migration and merging. This is a fundamental difference from high-temperature processes: high temperatures cause helium bubbles to grow, while the low-heat accumulation conditions of this invention ensure that the helium bubble can only shrink and not grow.

[0064] b) Dislocation Loop Reduction Mechanism (Electron Wind-Activated Slip Sweep): The high-energy electron flow of the same high-density pulsed current excites the core atoms of dislocations, lowering the Peierls barrier for dislocation initiation and activating previously pinned dislocation lines to begin slipping. These activated slip dislocation lines encounter surrounding irradiated dislocation loops (especially difficult-to-move Frank loops) during their movement. Through absorption, dragging, and other mechanisms, the slip dislocation lines sweep the dislocation loops from their original positions. Some dislocation loops are transported to intrinsically defective traps such as grain boundaries for annihilation, thereby reducing the density and average size of dislocation loops. This mechanism requires no high-temperature assistance and is purely driven by electron wind, thus it can be effectively implemented under low-heat accumulation conditions.

[0065] The two mechanisms described above work together to regulate the helium bubble and dislocation loop under the same set of limited high-density pulsed currents. Throughout the pulsed current application process, the temperature monitoring module provides real-time feedback on the surface temperature. Due to the limited number of pulses and the extremely short single-pulse energy input time, the macroscopic surface temperature never exceeds 110°C.

[0066] like Figure 1 The diagram shows a pulsed current processing method. Infrared thermography can be used to obtain the temperature of the alloy surface during each pulse processing step. Figure 1 (b), and the temperature distribution on the sample surface during each pulse treatment.

[0067] like Figure 2 As shown, the high-density pulsed current in this invention causes a localized high temperature around the helium bubble due to the flow effect around the helium bubble.

[0068] like Figure 3 As shown, according to molecular dynamics simulation results, the local high temperature around the helium bubble induces the dissociation of the helium bubble.

[0069] MD simulated the evolution of a helium bubble (containing 380 vacancies and 228 helium atoms) with a radius of 1 nm and a fixed helium / vacancy ratio of 0.6 after energy (simulating the thermal excitation effect of a pulsed current around the helium bubble) was injected around it. Figure 3 As shown in Figure a, the initial helium bubble is spherical. After an energy injection of 0.2 ps ( Figure 3 (b) The matrix atoms surrounding the bubble are rapidly heated, causing the bubble to deform. To elucidate the evolution process, the internal pressure of the bubble and the matrix temperature were monitored. Figure 3 c). As the internal pressure of the bubble increases, the surrounding atoms are compressed. When 1 ps of energy is injected ( Figure 3 d) The internal pressure of the bubble reaches 21.7 GPa, and helium atoms begin to escape, while the substrate temperature rises very slowly. With continued energy injection, the bubble pressure fluctuates between 21 and 25 GPa, and helium atoms are continuously released into the energy injection region. The increased temperature in this region accelerates the diffusion of helium atoms, causing them to move away from their original bubble position. After 2 ps of injection ( Figure 3 e), the substrate temperature rapidly rises to approximately 430 K, at which point helium atoms are dispersed throughout the region. After energy injection stops, the energy-injected region and the substrate cool rapidly, with the substrate temperature dropping to 340 K at 25 ps. Figure 3 (f, 3h), after which the temperature slowly decreased. The average temperature of a single pulse was approximately 370 K, close to the temperature monitored on the sample surface during electrical pulse treatment (approximately 109 °C). Figure 1 The helium atoms in the central region contract to form a new, smaller bubble, while the helium atoms near the bubble are reabsorbed. Figure 3 f), the final bubble size is smaller than the initial state.

[0070] like Figure 4 As shown, this illustrates the process by which a slip dislocation line encounters, interacts with, and ultimately absorbs / sweeps away Frank dislocation loops of different orientations.

[0071] When a slipped 1 / 2

[110] dislocation encounters a δ loop on its slip surface (Burgess vector is 1 / 3[1]), When the leading Shockley dislocation is attracted to the ring before contact, the ring’s Burgers vector undergoes a local change. Although the ring’s Burgers vector temporarily exhibits mixed characteristics during the interaction, the ring’s Burgers vector recovers to 1 / 3 of its original value after the dislocation bypasses the ring.[1] 1], and the ring did not undergo significant elimination or size change. Conversely, with the β ring (Burgess vector is 1 / 3[ In the interaction of 11], the ring is oriented perpendicular to the dislocation line, resulting in significant ring absorption ( Figure 4(b) : The dislocation trapping ring triggers a complex dislocation decomposition reaction, forming a cleavage; the ring's Burgers vector transforms into 1 / 6 parallel to the dislocation line. 12], the ring is then dragged along with the dislocation movement and is eventually removed from its initial position. With the α ring (1 / 3

[111] ) and the γ ring (1 / 3

[111] ) 1) When they interact, they form a 60° angle with the slip surface, resulting in two different outcomes. One case ( Figure 4 In case (c), the ring eliminates stacking faults by forming Shockley dislocations internally, and is subsequently completely absorbed by the dislocations, forming cleavages, leading to the complete elimination of the ring; in another case ( Figure 4 (d) In this case, the ring splits into two segments: the lower half is carried away by the slip dislocation, while the upper half remains in situ, and its Burgers vector is transformed to 1 / 2

[110] . These simulations clearly demonstrate that slip dislocations can effectively sweep away or annihilate dislocation rings with favorable orientation or within the trapping distance. Except for the δ variant, the other three variants can be completely or partially swept away. It can be expected that mobile dislocations can effectively transport dislocation rings to intrinsic traps (such as grain boundaries) within the material, which provides a reasonable mechanism for the significant reduction in dislocation ring density observed after electrical pulse treatment.

[0072] Compared to the untreated (nickel-based alloy components containing irradiation damage before treatment), after the helium bubbles and dislocation loops in the area to be repaired are repaired, the density of helium bubbles decreases, the average size of helium bubbles decreases, the density of dislocation loops decreases, and the average size of dislocation loops decreases.

[0073] Specifically, in this embodiment, experiments show that, as Figure 5 As shown, the helium bubble density decreased by 56% after treatment, and the average size decreased from 1.3 nm to 1.1 nm (shrinkage rather than growth). Due to low heat accumulation, Ostwald ripening of the helium bubbles was completely avoided. Figure 6 As shown, the dislocation loop density is reduced by 60%, and the average size is reduced.

[0074] like Figure 7 As shown, the effective hardness of the irradiated area is represented by the hardness at a depth of 50 nm. After irradiation, the hardness of the alloy increased from 6.5 GPa to 7.6 GPa. After current treatment, the hardness decreased to 6.7 GPa. That is, the hardening repair rate after current treatment is as high as (7.6-6.7) / (7.6-6.5) = 81.8%.

[0075] The method of this invention has the following advantages: it allows for direct on-site repair of large in-service components without the need to construct a vacuum chamber or introduce inert gas, making it highly applicable to engineering projects and truly achieving in-situ repair. It requires only 1-10 pulses (total energizing time in milliseconds), compared to traditional annealing (which takes several hours). The specific operation involves high-temperature annealing of the irradiated nickel-based alloy component in a vacuum furnace with a vacuum level higher than 10...-5 For annealing at Pa, annealing temperature > 600℃, and time > 1 hour (see references: Materials 9 (2016) 832.) or CN115148384A, long-term processing (240 minutes, 30 minutes, 5 minutes) reduces energy consumption and time by several orders of magnitude. Only one pulse power supply and electrodes are required, eliminating the need for auxiliary equipment such as ultrasound or lasers. The control logic is simple, facilitating integration into remote operation or robotic systems.

[0076] The mechanism of this invention can be extended to the regulation of irradiation damage of other nuclear metal materials (such as stainless steel, zirconium alloys, etc.).

[0077] If the temperature monitoring module does not provide real-time feedback on the surface temperature of the area to be repaired during the entire pulse current application process, the alloy temperature may rise rapidly, even causing the alloy to melt. If the temperature is not controlled, the alloy surface temperature will be too high and obvious oxidation marks will appear.

[0078] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for synergistic control of nickel-based alloy helium bubbles and dislocation loops based on a finite number of high-density pulse currents, characterized in that, Includes the following steps: S1. In an atmospheric environment, the pulse power module is connected to the electrode module, and the electrode module is made into contact with the area to be repaired of the nickel-based alloy component containing irradiation damage. The nanoscale defects generated inside the nickel-based alloy component containing irradiation damage include helium bubbles and dislocation loops. S2. Based on the degree of irradiation damage of the nickel-based alloy component containing irradiation damage, the controller presets pulse parameters, including the number of pulses. The preset number of pulses is 1 ≤ N ≤ 10. The temperature monitoring module is activated to collect the surface temperature data of the area to be repaired in real time to ensure that the component temperature does not exceed 110°C during pulse current treatment. S3. The controller controls the pulse power supply module to apply a set of pulse currents to the area to be repaired according to the preset number of pulses N, so as to complete the coordinated regulation of the nickel-based alloy helium bubble and dislocation loop. The total power-on time is in the millisecond range. During the entire pulse current application process, the temperature monitoring module provides real-time feedback on the surface temperature of the area to be repaired. If the surface temperature feedback of the area to be repaired reaches 90% of the threshold of 110℃, the controller pauses the output and waits for the temperature to drop to room temperature before continuing to apply the pulse current until N pulse processing is completed. S4. After the preset number of pulses N is completed, the controller shuts off the pulse power module, stops applying pulse current, and allows the area to be repaired to cool naturally to room temperature, thus completing the repair of the helium bubble and dislocation loop in the area to be repaired.

2. The method for synergistic control of nickel-based alloy helium bubbles and dislocation loops based on finite-order high-density pulse currents according to claim 1, characterized in that, In step S2, the pulse parameters also include peak current density, pulse width, pulse frequency, and pulse waveform.

3. The method for synergistic control of nickel-based alloy helium bubbles and dislocation loops based on finite-order high-density pulse currents according to claim 2, characterized in that, The peak current density is set to 171~200 A / mm². 2 ; The pulse width is 800~1000 μs; The pulse frequency is 80~120 Hz; The pulse waveform is a square wave.

4. The method for synergistic control of nickel-based alloy helium bubbles and dislocation loops based on finite-order high-density pulse currents according to claim 1, characterized in that, In step S2, the degree of irradiation damage of the nickel-based alloy component containing irradiation damage includes the initial density of the helium bubble, the average size of the helium bubble, the initial density of the dislocation loop, and the average size of the dislocation loop.

5. The method for synergistic control of nickel-based alloy helium bubbles and dislocation loops based on finite-order high-density pulse currents according to claim 1, characterized in that, In step S3, the synergistic regulation of the nickel-based alloy helium bubble and dislocation loop includes the synergistic excitation of the helium bubble reduction mechanism and the dislocation loop reduction mechanism.

6. The method for synergistic control of nickel-based alloy helium bubbles and dislocation loops based on finite-order high-density pulse currents according to claim 1, characterized in that, In step S4, as the area to be repaired is allowed to cool naturally to room temperature, the helium atoms and vacancies released from the helium bubble, as well as the point defects generated by the dislocation loops that have been eliminated, further diffuse to the inherent defect traps such as grain boundaries and surfaces and annihilate, thus completing the repair of the helium bubble and dislocation loops in the area to be repaired.

7. The method for synergistic control of nickel-based alloy helium bubbles and dislocation loops based on finite-order high-density pulse currents according to claim 1, characterized in that, Compared to the untreated state, after the helium bubbles and dislocation loops in the region to be repaired are repaired, the helium bubble density decreases, the average size of the helium bubbles decreases, the dislocation loop density decreases, and the average size of the dislocation loops decreases.

8. A system for repairing irradiation damage to nickel-based alloys using pulsed current, for implementing the method of synergistic control of helium bubbles and dislocation loops in nickel-based alloys based on a finite number of high-density pulsed currents as described in any one of claims 1-7, characterized in that, The system includes: A pulsed power supply module for applying pulsed current to the area to be repaired of a nickel-based alloy component containing radiation damage; The electrode module, connected to the pulse power supply module, forms electrical contact with the area to be repaired of the nickel-based alloy component containing radiation damage; The temperature monitoring module is used to monitor the surface temperature of the area to be repaired of the nickel-based alloy component containing irradiation damage, and to provide feedback to the controller to ensure that the macroscopic temperature does not exceed 110°C during the repair process. The controller is connected to the pulse power supply module and the temperature monitoring module to control the pulse current output of the pulse power supply module according to preset pulse parameters, and to dynamically adjust according to feedback from the temperature monitoring module.

9. The system for repairing irradiation damage to nickel-based alloys using pulsed current according to claim 8, characterized in that, The electrode module includes a pair of output electrodes; A pair of output electrodes form an electrical contact connection with the area to be repaired of a nickel-based alloy component containing irradiation damage.

10. The system for repairing irradiation damage to nickel-based alloys using pulsed current according to claim 8, characterized in that, The temperature monitoring module includes an infrared thermal imager.

Images