High-entropy alloy microcrack defect repairing method based on electromagnetic coupling field

Abstract

The invention discloses a high-entropy alloy microcrack defect repairing method based on an electromagnetic coupling field, which comprises the following steps: carrying out nondestructive inspection on a to-be-repaired high-entropy alloy component, and determining the position of a microcrack and geometric characteristics of the crack; electromagnetic coupling parameters are set according to the positions of the microcracks and geometric characteristics of the cracks; polishing the repaired part of the to-be-repaired high-entropy alloy component and the part connected with the electrode; the to-be-repaired high-entropy alloy component is clamped in electromagnetic coupling processing equipment, and electromagnetic coupling processing is conducted on the repaired part according to the electromagnetic coupling parameters; and carrying out nondestructive inspection on the repaired high-entropy alloy component so as to evaluate the repairing quality. According to the method, microcracks extremely prone to occurring in the preparation of the high-entropy alloy component through selective laser melting can be effectively repaired, the residual stress is adjusted, the quality of the high-entropy alloy component prepared through selective laser melting is improved, and application and popularization of the high-entropy alloy component prepared through selective laser melting in engineering practice are accelerated.

Description

Technical Field

[0001] The present invention belongs to the technical field of alloy repair, and in particular relates to a method for repairing microcrack defects in high entropy alloys based on an electromagnetic coupling field. Background Art

[0002] High-entropy alloys are alloys composed of five or more principal metal elements, with each element accounting for between 5% and 35%. Their core characteristic is the high-entropy effect, which causes their structure to tend to form a simple solid solution. Compared to traditional alloys, high-entropy alloys have excellent properties such as high strength, high toughness, corrosion resistance, high temperature resistance, and radiation resistance. Therefore, high-entropy alloys have significant application potential in aerospace, nuclear energy, medical implants, extreme environments, and hydrogen energy. In the aerospace field in particular, high-entropy alloys, due to their excellent high-temperature mechanical properties, are expected to replace nickel-based high-temperature alloys as a new material for manufacturing turbine blades, achieving weight reduction of turbine blades and significantly improving the performance of aircraft engines.

[0003] The main methods for preparing high-entropy alloys (HEAs) include vacuum arc melting, vacuum induction melting, and powder metallurgy. These methods have limitations in practical applications. Due to its low cooling rate, vacuum arc melting often leads to severe compositional segregation, coarse grains, numerous defects, and cross-adaptability to size and complex structures. Vacuum induction melting often results in compositional segregation and coarse grains, high production costs, and crucible contamination. Powder metallurgy often introduces powder impurities, resulting in poor product density and a long production process, making it difficult to produce products with complex structures. In contrast, additive manufacturing (AM) technology offers significant advantages in the preparation of HEAs. Selective laser melting (SLM) is one of the main AM methods for preparing HEAs. It enables the integrated formation of complex structures and high-precision HEA components. The high cooling rate generated by its rapid solidification also helps form a fine and uniform grain structure, thereby improving the mechanical properties of HEA components.

[0004] However, due to its layer-by-layer stacking process characteristics, the components cool down quickly during molding, which will generate residual stress inside the components, making it very easy for microcracks to form inside the components, seriously affecting the application of high-entropy alloy components in actual engineering.

[0005] To address the problem of microcracks easily forming in high-entropy alloy components fabricated by selective laser melting, methods such as controlling the stacking fault energy (SFE) to inhibit crack nucleation, controlling element segregation and optimizing precipitation phases, adjusting process parameters, and assisting with post-processing techniques are currently commonly used to reduce microcracks. However, these methods all have their limitations. Controlling the stacking fault energy and controlling element segregation and optimizing precipitation phases carries the risk of element burnout and contamination, resulting in deviations between the actual composition of the product and the designed value. Adjusting process parameters can reduce microcracks in the product, but the preparation process parameters vary for different alloy systems, requiring extensive experimental verification. Furthermore, the range of parameter adjustment is limited, making it difficult to balance both forming quality and efficiency. Post-processing techniques such as hot isostatic pressing can eliminate internal porosity in the product, but high temperatures can lead to grain coarsening, affecting the product quality of the high-entropy alloy component. Summary of the Invention

[0006] The purpose of the present invention is to address the above-mentioned deficiencies in the prior art and provide a high entropy alloy microcrack defect repair method based on electromagnetic coupling field, so as to solve the problem that the prior art microcrack repair method for high entropy alloy components prepared by laser selective melting has great limitations.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is: A method for repairing microcrack defects in a high entropy alloy based on an electromagnetic coupling field comprises the following steps: S1. Perform nondestructive testing on the high-entropy alloy component to be repaired to determine the location of microcracks and crack geometric characteristics; S2. Setting electromagnetic coupling parameters according to the microcrack location and crack geometry characteristics; S3. Grinding the repaired portion of the high-entropy alloy component to be repaired and the portion connected to the electrode; S4, clamping the high-entropy alloy component to be repaired in an electromagnetic coupling treatment device, and performing electromagnetic coupling treatment on the repaired part according to electromagnetic coupling parameters; S5. Perform nondestructive testing on the repaired high-entropy alloy components to evaluate the repair quality.

[0008] Furthermore, in S1, non-destructive testing is performed on the high-entropy alloy component to be repaired using a three-dimensional white light interferometer, ultrasonic testing, or radiographic testing to determine the location of microcracks and crack geometric characteristics.

[0009] Furthermore, the crack geometric characteristics include the direction, width, length and depth of the crack.

[0010] Furthermore, in S2, setting electromagnetic coupling parameters includes: According to the direction of the microcracks, the clamping direction, magnetic field direction and current direction of the high-entropy alloy component to be repaired are all set to be perpendicular to the direction of the microcracks.

[0011] Furthermore, in said S2, setting electromagnetic coupling parameters further includes: Clamping force is 0.2-10kN; Voltage U is 10-500V; The magnetic induction intensity B is 0-2T; The frequency of the electric pulse is 50 Hz; The number of electromagnetic coupling treatment groups is 10-20 groups.

[0012] Furthermore, based on Maxwell's equations, the electromagnetic field coupling relationship is constructed, which is specifically expressed as follows: Where, for Time period, the original magnetic field strength when the pulse electric field is zero; represents the vacuum permeability, Indicates the magnetic permeability of the high entropy alloy component to be repaired, I It represents the current flowing through the high entropy alloy component to be repaired during the electromagnetic coupling treatment; k is the correction factor; r 0 is the coil radius; 、 、 Indicates a time period.

[0013] Furthermore, the correction factor k Expressed as: Where, 、 、 、 Respectively 、 、 、 The correction coefficient of the coupled output magnetic field of the time period; K is the obstruction coefficient; θ 1 and θ 2 are the angles between the line connecting the farthest points at both ends of the high entropy alloy component to be repaired and the center point of the high entropy alloy component to be repaired and the line connecting the two electrodes.

[0014] Furthermore, in S5, non-destructive testing is performed on the repaired high-entropy alloy component to evaluate the repair quality, specifically including: Perform nondestructive testing on the repaired high-entropy alloy component using ultrasonic testing or radiographic testing. Compare the nondestructive testing results of S1 and S5 to determine whether the microcrack healing effect meets the expected requirements. If not, return to S2 until the microcrack healing effect meets the expected requirements. If it meets the expected requirements, perform quality inspection on the repaired high-entropy alloy component.

[0015] The high entropy alloy microcrack defect repair method based on electromagnetic coupling field provided by the present invention has the following beneficial effects: 1. The electromagnetic coupling treatment of the present invention does not alter the workpiece's shape or structure, nor does it affect its original assembly and use. Furthermore, the electromagnetic coupling treatment is low-cost, requiring no additional raw materials, thus reducing the economic cost of post-processing the high-entropy alloy. Furthermore, the electromagnetic coupling treatment cycle is short, with the entire process taking less than 5 minutes, reducing the time cost of post-processing the high-entropy alloy workpiece.

[0016] 2. The electromagnetic coupling technology of the present invention is driven by electricity as energy, which is clean and environmentally friendly. The electromagnetic coupling processing equipment is easy to operate and has low working environment requirements. It only requires using a special clamp to fix the workpiece to be processed in the working chamber, connecting it to the electrode, and entering the electromagnetic coupling processing parameters to start processing. The processing process is carried out automatically without any other steps. After the processing is completed, the workpiece can be removed.

[0017] 3. Compared with the methods of regulating stacking fault energy and controlling element segregation and precipitate phase optimization, the electromagnetic coupling treatment of the present invention does not have the risk of element burnout and contamination. Compared with the method of adjusting the process parameters of laser selective melting, the electromagnetic coupling treatment does not require a large number of experimental verifications for each alloy component, resulting in a waste of high-entropy alloy components. At the same time, the electromagnetic coupling treatment has a high degree of freedom in adjusting the parameters, and there is no need to worry about damaging the product quality of the high-entropy alloy components. Compared with post-processing methods such as hot isostatic pressing and heat treatment, the electromagnetic coupling treatment has almost no temperature rise and will not cause the internal structure of the high-entropy alloy components to coarsen the grains, affecting the mechanical properties of the components. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a flow chart of the method for repairing microcrack defects in high entropy alloys based on electromagnetic coupling fields in Example 1 of the present invention.

[0019] Figure 2 This is a comparison diagram before and after the microcrack test of the high entropy alloy in Example 2 of the present invention.

[0020] Figure 3 is the angle in Example 1 of the present invention θ 1 and θ 2. DETAILED DESCRIPTION

[0021] The specific embodiments of the present invention are described below to facilitate understanding of the present invention by those skilled in the art. However, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the appended claims, these changes are obvious, and all inventions and creations utilizing the concepts of the present invention are protected.

[0022] Example 1 This embodiment provides a method for repairing microcrack defects in high-entropy alloys based on an electromagnetic coupling field. The electromagnetic coupling processing technology of this embodiment couples an electric field with a magnetic field to repair microcracks existing inside a high-entropy alloy product through electromagnetic force. During the specific processing, a portion of the pulse current is directly loaded on the workpiece to be processed, and another portion of the pulse current generates a pulsed magnetic field through an excitation coil to act on the workpiece. The electromagnetic coupling processing technology is short in time and effective in repairing microcracks in high-entropy alloys, with the entire process taking no more than 5 minutes. The entire process uses electricity, which is clean and environmentally friendly. At the same time, the electromagnetic coupling processing technology can also regulate the residual stress of the workpiece, greatly extending the service life of the workpiece. For high-entropy alloy components with complex shapes and large sizes, the specific location and morphology of the defect can be determined through non-destructive testing and microcrack modeling, and then electromagnetic coupling processing can be accurately performed on the defect site without being restricted by the shape and size of the workpiece. Compared with regulating stacking fault energy and controlling element segregation and precipitate phase optimization, there is no risk of element burnout and contamination; compared with the method of adjusting the laser selective melting process parameters, the electromagnetic coupling treatment in this embodiment does not require a large number of experimental verifications for each alloy component, resulting in waste of high-entropy alloy components. At the same time, the electromagnetic coupling treatment parameters have a high degree of freedom in adjustment, and there is no need to worry about damaging the product quality of the high-entropy alloy components; compared with post-processing methods such as hot isostatic pressing and heat treatment, the electromagnetic coupling treatment has almost no temperature rise, and will not cause coarsening of the internal structure grains of the high-entropy alloy components, affecting the mechanical properties of the components.

[0023] refer to Figure 1 , this embodiment specifically includes the following contents: S1. Perform nondestructive testing on the high-entropy alloy component to be repaired to determine the location of microcracks and crack geometric characteristics; Specifically, this embodiment uses a three-dimensional white light interferometer, ultrasonic flaw detection or radiographic flaw detection to perform non-destructive flaw detection on the high-entropy alloy component to be repaired to determine the location of microcracks and the geometric characteristics of the cracks.

[0024] Among them, the crack geometric characteristics include the crack direction, width, length and depth.

[0025] In a specific embodiment, based on the results of nondestructive testing, the direction, length, width and depth of the microcracks are digitally modeled using mWorks software, and a microcrack model is established; subsequently, a database of the corresponding relationship between the microcrack model, electromagnetic coupling processing parameters and processing effects is constructed.

[0026] S2. Setting electromagnetic coupling parameters according to the microcrack location and crack geometry characteristics; In some embodiments, according to the direction of the microcracks, the clamping direction, magnetic field direction and current direction of the high-entropy alloy component to be repaired are all set to be perpendicular to the direction of the microcracks.

[0027] The clamping force is determined according to the depth, length, and width of the microcracks, and the electromagnetic coupling parameters are set as follows: Clamping force is 0.2-10kN; Voltage U is 10-500V; The magnetic induction intensity B is 0-2T; The frequency of the electric pulse is 50 Hz; The number of electromagnetic coupling treatment groups is 10-20 groups.

[0028] The electromagnetic coupling treatment parameters were adjusted and optimized based on the microcrack model simulation process and results. At the same time, during the electromagnetic coupling treatment process, a certain quantitative coupling relationship exists between the electromagnetic fields. By combining the traditional Maxwell equations with multiple experimental and simulation results, the following relationship between the electromagnetic fields was obtained: Where, for Time period, the original magnetic field strength when the pulse electric field is zero; represents the vacuum permeability, Indicates the magnetic permeability of the high entropy alloy component to be repaired, I It represents the current flowing through the high entropy alloy component to be repaired during the electromagnetic coupling treatment; k is the correction factor; r 0 is the coil radius; 、 、 Indicates a time period.

[0029] Among them, the correction coefficient k Expressed as: Where, 、 、 、 Respectively 、 、 、 The correction coefficient of the time period coupling output magnetic field; K is the obstruction coefficient. According to the law of Ludwig, the magnetic field of the induced current will always obstruct the change of the magnetic flux causing the induced current. Therefore, the magnetic field generated by the negative pulse current is opposite to the original magnetic field. Therefore, the original magnetic field and the induced magnetic field have a mutual obstruction effect, resulting in the attenuation of the negative pulse induced magnetic field. The obstruction coefficient K quantifies the attenuation of the negative pulse induced magnetic field due to the mutual obstruction effect between the original magnetic field and the induced magnetic field. θ 1 and θ 2 are the angles between the line connecting the farthest points at both ends of the sample (the high entropy alloy component to be repaired) and the center point of the sample (the high entropy alloy component to be repaired) and the line connecting the two electrodes, as shown in Figure 3 shown.

[0030] S3. Grinding the repaired portion of the high-entropy alloy component to be repaired and the portion connected to the electrode; S4, clamping the high-entropy alloy component to be repaired in an electromagnetic coupling treatment device, and performing electromagnetic coupling treatment on the repaired part according to electromagnetic coupling parameters; S5. Perform nondestructive testing on the repaired high-entropy alloy components to evaluate the repair quality.

[0031] Perform nondestructive testing on the repaired high-entropy alloy component using ultrasonic testing or radiographic testing. Compare the nondestructive testing results of S1 and S5 to determine whether the microcrack healing effect meets the expected requirements. If not, return to S2 until the microcrack healing effect meets the expected requirements. If it meets the expected requirements, perform quality inspection on the repaired high-entropy alloy component.

[0032] Example 2 This embodiment is a further optimization of the first embodiment, and uses electromagnetic coupling processing technology to process the high entropy alloy component prepared by laser selective melting to achieve the purpose of repairing cracks, which specifically includes the following contents: A1. Prepare the high-entropy alloy component to be repaired, which is prepared by laser selective melting. Perform non-destructive testing on the high-entropy alloy component to be repaired using ultrasonic testing or radiographic testing to determine the defect location.

[0033] A2. Based on the inspection results of three-dimensional white light interferometer, ultrasonic testing or radiographic testing, digital modeling is performed on the direction, length, width and depth of microcracks.

[0034] Based on the various characteristics of the microcracks in the modeling, the clamping direction was determined to be perpendicular to the crack direction. The electromagnetic coupling parameters were set based on the crack depth, width, and length. The microcrack model and the electromagnetic coupling treatment parameters developed in the previous step were imported into the simulation program. Based on the simulation process and results, the electromagnetic coupling treatment parameters were optimized, resulting in the following parameters: the clamping direction, magnetic field direction, and current direction were perpendicular to the microcrack direction, the clamping force was 0.2 kN, the voltage U = 31 V, the magnetic field intensity B = 1.5 T, the electric pulse frequency was 50 Hz, and the number of electromagnetic coupling treatment groups was 20.

[0035] A3. Grind and polish the surface of defective parts of the high-entropy alloy components to a mirror finish, and use a scanning electron microscope (SEM) to observe and mark the microcracks of the specimens.

[0036] A4. Fix the high-entropy alloy sample with a special fixture, connect it to a special electrode, place it in the working chamber composed of the excitation coil, adjust the electromagnetic coupling processing parameters to the set parameters, and perform electromagnetic coupling processing.

[0037] A5. Scanning electron microscope was used to observe the morphology of microcracks at the marked points after electromagnetic coupling treatment. The results showed that after electromagnetic coupling treatment, the microcracks at the marked points had a good healing effect, from micron-scale cracks to nano-scale cracks, and some small crack branches had been completely healed, as shown below. Figure 2 shown.

[0038] The present invention uses ultrasonic testing or radiographic testing to perform nondestructive testing on the high-entropy alloy component to be repaired. Nanoscale cracks and sub-nanoscale cracks on the surface of the high-entropy alloy component are completely repaired, and micron-scale cracks gradually heal into nanoscale cracks.

[0039] Although the specific embodiments of the invention are described in detail in conjunction with the accompanying drawings, this should not be construed as limiting the scope of protection of this patent. Within the scope described by the claims, various modifications and variations that can be made by those skilled in the art without creative work still fall within the scope of protection of this patent.

Claims

1. A method for repairing microcrack defects in high entropy alloys based on electromagnetic coupling fields, characterized in that: The following steps are involved: S1. Perform nondestructive testing on the high-entropy alloy component to be repaired to determine the location of microcracks and crack geometric characteristics; S2. Setting electromagnetic coupling parameters according to the microcrack location and crack geometry characteristics; S3. Grinding the repaired portion of the high-entropy alloy component to be repaired and the portion connected to the electrode; S4, clamping the high-entropy alloy component to be repaired in an electromagnetic coupling treatment device, and performing electromagnetic coupling treatment on the repaired part according to electromagnetic coupling parameters; S5. Perform nondestructive testing on the repaired high-entropy alloy components to evaluate the repair quality.

2. The method for repairing microcrack defects in high entropy alloys based on electromagnetic coupling fields according to claim 1, characterized in that: In S1, non-destructive testing is performed on the high-entropy alloy component to be repaired using a three-dimensional white light interferometer, ultrasonic testing, or radiographic testing to determine the location of microcracks and the geometric characteristics of the cracks.

3. The method for repairing microcrack defects in high entropy alloys based on electromagnetic coupling fields according to claim 2, characterized in that: The crack geometric characteristics include the direction, width, length and depth of the crack.

4. The method for repairing microcrack defects in high entropy alloys based on electromagnetic coupling fields according to claim 1, characterized in that: In S2, electromagnetic coupling parameters are set, including: According to the direction of the microcracks, the clamping direction, magnetic field direction and current direction of the high-entropy alloy component to be repaired are all set to be perpendicular to the direction of the microcracks.

5. The method for repairing microcrack defects in high entropy alloys based on electromagnetic coupling fields according to claim 1, characterized in that: In the above S2, setting electromagnetic coupling parameters also includes: Clamping force is 0.2-10kN; Voltage U is 10-500V; The magnetic induction intensity B is 0-2T; The frequency of the electric pulse is 50 Hz; The number of electromagnetic coupling treatment groups is 10-20 groups.

6. The method for repairing microcrack defects of high entropy alloys based on electromagnetic coupling fields according to claim 5, characterized in that: Based on Maxwell's equations, the electromagnetic field coupling relationship is constructed, which is specifically expressed as: Where, for Time period, the original magnetic field strength when the pulse electric field is zero; represents the vacuum permeability, Indicates the magnetic permeability of the high entropy alloy component to be repaired, I It represents the current flowing through the high entropy alloy component to be repaired during the electromagnetic coupling treatment; k is the correction factor; r 0 is the coil radius; 、 、 Indicates a time period.

7. The method for repairing microcrack defects of high entropy alloys based on electromagnetic coupling fields according to claim 6, characterized in that: Correction factor k Expressed as: Where, 、 、 、 Respectively 、 、 、 The correction coefficient of the coupled output magnetic field of the time period; K is the obstruction coefficient; θ 1 and θ 2 are the angles between the line connecting the farthest points at both ends of the high entropy alloy component to be repaired and the center point of the high entropy alloy component to be repaired and the line connecting the two electrodes.

8. The method for repairing microcrack defects of high entropy alloys based on electromagnetic coupling field according to claim 1, characterized in that: In S5, non-destructive testing is performed on the repaired high-entropy alloy component to evaluate the repair quality, specifically including: Perform nondestructive testing on the repaired high-entropy alloy component using ultrasonic testing or radiographic testing. Compare the nondestructive testing results of S1 and S5 to determine whether the microcrack healing effect meets the expected requirements. If not, return to S2 until the microcrack healing effect meets the expected requirements. If it meets the expected requirements, perform quality inspection on the repaired high-entropy alloy component.

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