Method for preparing low driving force ni-ti-cu alloy based on directional energy deposition

Abstract

The application relates to a low-driving-force NiTiCu alloy preparation method based on directional energy deposition. A deposited-state NiTiCu alloy is prepared through a laser direct energy deposition mode, and then the deposited-state NiTiCu alloy is subjected to twice heat treatment to obtain an aging-state NiTiCu alloy. The application adopts a laser direct energy deposition device to prepare the NiTiCu alloy, can prepare a complex NiTiCu alloy component with good formability and high density, and is not affected by the size. The deposited-state NiTiCu alloy sample is subjected to twice heat treatment of high-temperature solid solution treatment and low-temperature aging treatment, and the obtained aging-state NiTiCu alloy sample has a high super-elastic recovery rate under a lower driving stress.

Description

Technical Field

[0001] This invention relates to the field of shape memory alloy technology, and in particular to a method for preparing low-driving-force NiTiCu alloys based on directional energy deposition. Background Technology

[0002] NiTi-based shape memory alloys (SMAs) exhibit excellent mechanical properties, fatigue resistance, wear and corrosion resistance, biocompatibility, and superior shape memory effect and superelasticity due to their thermoelastic martensitic phase transformation. They are currently widely used in aerospace, automotive, and biomedical fields. However, NiTi binary alloys have a relatively high phase transformation activation energy, requiring significant external stress to drive the martensitic phase transformation and generate strain in the parent phase state.

[0003] Adding copper, an element with antibacterial properties, to NiTi alloys yields NiTiCu shape memory alloys that combine antibacterial functions with superelasticity and shape memory effects. The addition of Cu does not alter the crystal structure of the parent phase, and it reduces the phase transformation hysteresis and lowers the critical stress for inducing martensitic transformation. Therefore, NiTiCu alloys respond rapidly to external stimuli, allowing for the fabrication of specialized shape memory alloy components utilizing their low driving stress characteristics.

[0004] In the existing technology, the parts prepared by traditional methods such as melting and casting and powder metallurgy for the preparation of NiTiCu alloys have simple structures. The hot isostatic pressing method is not economical and the process is complicated. The molds for metal injection molding are difficult to process. The samples synthesized by self-propagating high temperature have poor molding quality. The alloys prepared by non-consumable arc melting are small. The defects of these methods have seriously limited the promotion and application of NiTiCu alloys. Summary of the Invention

[0005] Therefore, it is necessary to provide a method for preparing low-driving-force NiTiCu alloys based on directional energy deposition to address the above-mentioned technical problems. The prepared NiTiCu alloys have low driving stress and high elastic recovery rate. Furthermore, the preparation of NiTiCu alloys based on directional energy deposition can realize the preparation of complex parts that are not affected by size.

[0006] This invention provides a method for preparing low-driving-force NiTiCu alloys based on directional energy deposition, comprising the following steps:

[0007] S1: After fixing the NiTi alloy substrate in the forming chamber of the laser direct energy deposition equipment, the oxygen content of the atmosphere in the forming chamber is reduced to below 100ppm using high-purity circulating argon gas.

[0008] S2: Set the parameters of the laser direct energy deposition equipment, and continuously deposit the dried NiTiCu pre-alloyed powder on the NiTi alloy substrate to form a preset solid model and obtain a NiTiCu alloy sample. After the NiTiCu alloy sample in the molding chamber cools to room temperature, it is taken out and cut into the target test size to obtain the deposited NiTiCu alloy sample.

[0009] S3: Place the deposited NiTiCu alloy sample in a vacuum quartz tube, and then place the vacuum quartz tube in a muffle furnace at 900℃~1000℃ for 1h~2h for high-temperature solution treatment. After the high-temperature solution treatment is completed, remove the vacuum quartz tube from the muffle furnace and quickly place it in an ice-water mixture for the first quenching.

[0010] S4: After the first quenching, the NiTiCu alloy sample obtained is placed in a vacuum quartz tube again, and then the vacuum quartz tube is placed in a muffle furnace at 600℃~700℃ for 2h~3h for low-temperature aging treatment. After the low-temperature aging treatment, the vacuum quartz tube is taken out of the muffle furnace and quickly placed in an ice-water mixture for a second quenching. After the second quenching, an aged NiTiCu alloy sample is obtained.

[0011] In one embodiment, the parameters of the laser direct energy deposition equipment include: laser power of 1800-2200W, scanning speed of 300mm / s-900mm / s, laser spot diameter of 3mm-5mm, and layer-to-layer overlap rate of 40-60%.

[0012] In one embodiment, when the dried NiTiCu pre-alloyed powder is deposited on the NiTi alloy substrate for the first time, a laser beam emitted by a semiconductor laser energy source is used to act on the surface of the NiTi alloy substrate to form a molten pool. Then, the dried NiTiCu pre-alloyed powder is simultaneously fed into the molten pool through a coaxial powder feeding nozzle under the protection of high-purity argon gas at a powder feeding rate of 10-11 g / min to melt and solidify on the NiTi alloy substrate to form the first NiTiCu alloy deposition layer.

[0013] When the dried NiTiCu pre-alloyed powder is deposited on a NiTi alloy substrate more than once, a laser beam emitted from a semiconductor laser energy source is used to act on the surface of the previously formed NiTiCu alloy deposition layer to form a molten pool. Then, the dried NiTiCu pre-alloyed powder is simultaneously fed into the molten pool through a coaxial powder feeding nozzle under the protection of high-purity argon gas at a powder feeding rate of 10-11 g / min to melt and solidify on the previously formed NiTiCu alloy deposition layer to form the current NiTiCu alloy deposition layer.

[0014] In the next deposition process, the laser energy source and the powder feeding nozzle are simultaneously raised by 0.4 mm to 0.5 mm compared to the previous deposition process.

[0015] In one embodiment, the power of the semiconductor laser energy source is 6000W.

[0016] In one embodiment, the drying process of NiTiCu pre-alloyed powder involves drying NiTiCu pre-alloyed powder with a particle diameter of 53μm to 150μm at 110℃ to 130℃ and a vacuum degree of -0.08MPa to -0.1MPa for 2h to 3h, and then cooling it to room temperature.

[0017] In one embodiment, the laser direct energy deposition apparatus performs multiple consecutive depositions in a reciprocating cross-grating manner.

[0018] In one embodiment, the internal pressure of the vacuum quartz tube is 3.5 × 10⁻⁶. -4 Pa.

[0019] The beneficial effects of this invention are: This invention uses laser direct energy deposition equipment to prepare NiTiCu alloys, which can prepare complex NiTiCu alloy samples with good formability and high density that are not affected by size. The aged NiTiCu alloy samples obtained have lower driving stress and high hyperelastic recovery rate. Attached Figure Description

[0020] Figure 1 This is one of the flowcharts of the method for preparing low-driving-force NiTiCu alloy based on directional energy deposition provided in the embodiments of the present invention;

[0021] Figure 2 This is a DSC curve of the deposited sample under different heating / cooling rates in Example 1 of the present invention, where M s The martensitic phase transformation initiation temperature, M f The martensitic phase transformation end temperature, M p The peak temperature of the martensitic phase transformation, A s The initiation temperature of the reverse martensitic phase transformation, A f The temperature at which the reverse martensitic phase transformation ends, A p This is the peak temperature of the reverse martensitic phase transformation;

[0022] Figure 3 This is a schematic diagram of data fitting for determining the phase transition activation energy during cooling using the Kissinger method;

[0023] Figure 4 The deposited sample in Example 1 of this invention is in A f Uniaxial compressive stress-strain curve at +10~15℃;

[0024] Figure 5 This is a schematic diagram of the transmission bright-field image of the aged sample in Embodiment 1 of the present invention. Figure 5 (b) is Figure 5 (a) Selecting the electron diffraction pattern at position 1, Figure 5 (c) is Figure 5 (a) Selecting the electron diffraction pattern at position 2;

[0025] Figure 6 This is a DSC curve of the aged sample under different heating / cooling rates in Example 1 of the present invention, where M s The martensitic phase transformation initiation temperature, M f The martensitic phase transformation end temperature, M p The peak temperature of the martensitic phase transformation, A s The initiation temperature of the reverse martensitic phase transformation, A f The temperature at which the reverse martensitic phase transformation ends, A p This is the peak temperature of the reverse martensitic phase transformation;

[0026] Figure 7 This is a uniaxial compressive stress-strain curve of the aged sample at room temperature in Example 1 of this invention;

[0027] Figure 8 This is the uniaxial compressive stress-strain curve of the aged sample in Example 1 of the present invention under 4% pre-strain. Detailed Implementation

[0028] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0030] In one embodiment, a method for preparing a low-driving-force NiTiCu alloy based on directional energy deposition includes the following steps:

[0031] S1: After fixing the NiTi alloy substrate in the forming chamber of the laser direct energy deposition equipment, the oxygen content of the atmosphere in the forming chamber is reduced to below 100ppm using high-purity circulating argon gas.

[0032] Argon gas is used to reduce the oxygen content in the molding chamber atmosphere to minimize the impact of impurities.

[0033] S2: Set the parameters of the laser direct energy deposition equipment, and continuously deposit the dried NiTiCu pre-alloyed powder on the NiTi alloy substrate to form a preset solid model, thereby obtaining a NiTiCu alloy sample. After the NiTiCu alloy sample in the molding chamber cools to room temperature, it is taken out and cut into the target test size to obtain the deposited NiTiCu alloy sample.

[0034] The preset solid model is a three-dimensional CAD solid model that has been created in advance by the computer.

[0035] Specifically, the parameters of the laser direct energy deposition (LDED) equipment include: laser power of 1800–2200W, scanning speed of 300 mm / s–900 mm / s, laser spot diameter of 3 mm–5 mm, and layer overlap of 40–60%. The LDED equipment performs multiple continuous depositions using a reciprocating cross-grating method.

[0036] When the dried NiTiCu pre-alloyed powder is deposited on the NiTi alloy substrate for the first time, a laser beam emitted by a semiconductor laser energy source is used to act on the surface of the NiTi alloy substrate to form a molten pool. Then, the dried NiTiCu pre-alloyed powder is fed into the molten pool at a feeding rate of 10-11 g / min through a coaxial powder feeding nozzle under the protection of high-purity argon gas to melt and solidify on the NiTi alloy substrate to form the first NiTiCu alloy deposition layer.

[0037] When the dried NiTiCu pre-alloyed powder is deposited on a NiTi alloy substrate more than once, a laser beam emitted from a semiconductor laser energy source is used to act on the surface of the previously formed NiTiCu alloy deposition layer to form a molten pool. Then, the dried NiTiCu pre-alloyed powder is simultaneously fed into the molten pool through a coaxial powder feeding nozzle under the protection of high-purity argon gas at a powder feeding rate of 10-11 g / min to melt and solidify on the previously formed NiTiCu alloy deposition layer to form the current NiTiCu alloy deposition layer.

[0038] In each subsequent deposition process, the laser energy source and the powder feeding nozzle are simultaneously raised by 0.4mm to 0.5mm compared to the previous deposition process. The power of the semiconductor laser energy source is 6000W.

[0039] S3: Place the deposited NiTiCu alloy sample in a vacuum quartz tube, and then place the vacuum quartz tube in a muffle furnace at 900℃~1000℃ for 1h~2h for high-temperature solution treatment. After the high-temperature solution treatment is completed, remove the vacuum quartz tube from the muffle furnace and quickly place it in an ice-water mixture for the first quenching.

[0040] Specifically, the internal pressure of the vacuum quartz tube is 3.5 × 10⁻⁶. -4 The process of placing the sample in a vacuum quartz tube involves placing the deposited NiTiCu alloy sample inside the quartz tube and connecting it to a vacuum device, then evacuating the tube to a pressure of 3.5 × 10⁻⁶ Pa. -4 After Pa, the tube is sealed. At this point, the sealed quartz tube will maintain a temperature of 3.5 × 10⁻⁶. -4 A vacuum level of Pa is used to ensure that the sample is kept under high vacuum during heat treatment and will not be oxidized.

[0041] S4: After the first quenching, the NiTiCu alloy sample obtained is placed in a vacuum quartz tube again, and then the vacuum quartz tube is placed in a muffle furnace at 600℃~700℃ for 2h~3h for low-temperature aging treatment. After the low-temperature aging treatment, the vacuum quartz tube is taken out of the muffle furnace and quickly placed in an ice-water mixture for a second quenching. After the second quenching, an aged NiTiCu alloy sample is obtained.

[0042] In one embodiment, the drying process of the NiTiCu pre-alloyed powder involves drying NiTiCu pre-alloyed powder with a particle diameter of 53μm to 150μm at 110℃ to 130℃ and a vacuum degree of -0.08MPa to -0.1MPa for 2 hours to 3 hours, followed by cooling to room temperature. Drying is used to remove moisture from the NiTiCu pre-alloyed powder.

[0043] In this embodiment, a NiTiCu alloy with excellent formability and high density can be obtained through directional energy deposition, ensuring that the mechanical properties of the formed sample are equivalent to or even better than those of cast or forged NiTiCu alloy samples of the same composition. Furthermore, by performing two heat treatments on the deposited NiTiCu alloy sample prepared by directional energy deposition, the microstructure of the deposited NiTiCu alloy can be controlled, resulting in an aged NiTiCu alloy sample with lower driving stress and higher hyperelastic recovery rate.

[0044] The following are specific examples.

[0045] Example 1

[0046] A method for preparing low-driving-force NiTiCu alloys based on directional energy deposition includes the following steps:

[0047] Step 1: NiTiCu pre-alloyed powder with a particle diameter of 53–150 μm is dried at 120 °C and a vacuum of -0.092 MPa for 2 hours to remove adsorbed moisture. After cooling to room temperature, the dried NiTiCu pre-alloyed powder is removed and placed in a high-precision, high-speed powder feeder. The particle diameter of the NiTiCu pre-alloyed powder is inconsistent, ranging from 53 to 150 μm.

[0048] Step 2: Place and fix a NiTi alloy substrate with dimensions of 100×100×10mm in the forming chamber of the laser direct energy deposition equipment. Use high-purity circulating argon gas to purify the oxygen content in the forming chamber and control it to below 100ppm to ensure the forming quality of the component.

[0049] Step 3: Set the laser power to 2200W, scanning speed to 600mm / s, laser spot diameter to 3mm, and layer overlap rate to 50%. Start the 6000W semiconductor laser energy source. The laser beam acts on the substrate surface to form a molten pool. Dry NiTiCu pre-alloyed powder is simultaneously fed into the molten pool through a coaxial powder feeding nozzle at a powder feeding rate of 11g / min under the protection of high-purity argon gas. The powder then rapidly melts and solidifies in the molten pool onto the NiTi alloy substrate, forming the first deposition layer. After the first layer is deposited, the laser energy source and powder feeding nozzle are simultaneously raised by 0.4mm for a second deposition on the first layer. This process continues until the final NiTiCu alloy sample is formed based on the computer-generated 3D CAD solid model. The direct energy deposition equipment uses a reciprocating cross-grating scanning method for continuous deposition.

[0050] Step 4: After the forming is completed, turn off the laser and the powder feeding system, wait for the NiTiCu alloy sample to cool to room temperature, turn off the high-purity circulating argon gas, take out the NiTi alloy substrate with deposited NiTiCu alloy, use an electrical discharge wire cutting device to cut the deposited NiTiCu alloy, and then cut the deposited NiTiCu alloy sample according to the target test size requirements.

[0051] Step 5: Place the deposited NiTiCu alloy sample in a quartz tube and evacuate to a pressure of 3.5 × 10⁻⁶. -4 After sealing, the vacuum quartz tube was placed in a muffle furnace at 900°C and kept at that temperature for 1 hour for high-temperature solution treatment. After the solution treatment was completed, the NiTiCu alloy sample was quickly removed and placed in an ice-water mixture (0°C) for the first quenching.

[0052] Step 6: Place the NiTiCu alloy sample, after the first quenching, back into the quartz tube and evacuate to a pressure of 3.5 × 10⁻⁶. -4After sealing, the sample was placed in a muffle furnace at 650°C for 2 hours for low-temperature aging. After aging, the NiTiCu alloy sample was quickly removed and placed in an ice-water mixture for a second quenching, thus obtaining the aged NiTiCu alloy sample.

[0053] Differential scanning calorimetry (DSC) analysis was performed on the sedimentary sample obtained in Example 1, and the results were as follows: Figure 2 The DSC curves are shown at different heating / cooling rates. Figure 2 The phase transition temperature of a deposited sample at a given rate can be determined using the tangent method. For example... Figure 3 As shown, by numerically fitting the peak temperatures of the cooling processes at different rates using the Kissinger method, the phase transformation activation energy E of the deposited NiTiCu alloy can be obtained as 28.29412 ± 4.38747 KJ / mol. The lower the phase transformation activation energy (E), the higher the critical driving stress (σ) required to induce the martensitic phase transformation. SIM The lower the value of the critical driving stress, the smaller the phase transformation activation energy of the deposited NiTiCu alloy, indicating that it requires a low critical driving stress to induce a martensitic phase transformation. Figure 4 As shown, Figure 4 ε SE For recoverable dependent variables, The sedimentary sample obtained in Example 1 was subjected to A f Compression superelasticity tests were conducted above the specified temperature. The critical stress (σ) at which the alloy induced a martensitic transformation was determined when 4%, 6%, and 8% compressive strain were applied. SIM The pressures were 375.5 MPa, 403.2 MPa, and 407.8 MPa, respectively, and their hyperelastic recovery rates were calculated to be 95.98%, 93.30%, and 89.41%, respectively.

[0054] like Figure 5 As shown, TEM analysis of the aged NiTiCu alloy sample obtained in Example 1 revealed continuous lenticular coherent C11 precipitates along grain boundaries in the matrix. b The Ti(NiCu)2 phase contains a large number of thin, plate-like coherent C11 particles with specific orientations densely distributed within the crystal. bThe precipitated Ti(NiCu)2 phase contains a high density of tangled dislocations. This coherent Ti(NiCu)2 phase, integrated with the matrix, exhibits strong strain field contrast, effectively inhibiting dislocation movement and strengthening the parent phase. It also facilitates the preferred orientation of martensite variants within the alloy, macroscopically manifesting as low driving stress and high hyperelastic recovery in the aged NiTiCu alloy. Furthermore, the abundant dislocation accumulation effectively increases the critical slip stress of the parent phase, further enhancing the alloy's hyperelastic recovery. Further differential scanning calorimetry (DSC) analysis of the aged NiTiCu alloy sample yielded the following results: Figure 6 The DSC curves are shown under different heating / cooling rates. After determining the phase transition temperature of the aged sample using the tangent method, the results are compared... Figure 2 and Figure 6 It was found that the phase transformation temperature of the heat-treated aged NiTiCu alloy sample was significantly lower than that of the deposited NiTiCu alloy sample, dropping to below 25°C. The phase transformation peak became sharper, and the phase transformation hysteresis narrower. At this point, the aged NiTiCu alloy sample only needs to overcome the phase transformation barrier to activate the martensitic phase transformation under room temperature loading, unlike the deposited NiTiCu alloy sample which requires overcoming both the phase transformation barrier and the temperature barrier. Therefore, the aged NiTiCu alloy sample exhibits lower driving stress. Figure 7 As shown, the aged sample obtained in Example 1 was subjected to compressive superelasticity testing at room temperature. When 4%, 6%, and 8% compressive loading were applied, the critical stress (σ) for inducing martensitic phase transformation in the aged NiTiCu alloy sample was determined. SIM The stress was approximately 270–282 MPa, and the hyperelastic recovery rate of the samples was consistently above 90%. This indicates that the aged NiTiCu alloy samples still exhibit a high hyperelastic recovery rate even with lower driving stress, making them suitable for the development and promotion of sensitive actuators with high response frequencies. In particular, when the pre-compression loading strain was 8%, the hyperelastic recovery rate increased to 93.71% compared to the deposited state. Figure 8 As shown, Figure 8 This is the uniaxial compressive stress-strain curve of the aged sample in this embodiment under 4% pre-strain. The aged NiTiCu alloy sample obtained in Example 1 was subjected to 4% uniaxial compressive loading, and the maximum feasible temperature range of its superelastic recovery rate (calculated as 86.93% at 51℃) was studied by controlling the temperature chamber. The results show that the alloy has a wide temperature range of about 21 to 46℃, and the human body's perceived temperature is exactly within this range. Combined with the low driving stress of the alloy, it can be proved that the NiTiCu alloy prepared by the method of this embodiment can be used in biomedicine.

[0055] Example 2

[0056] The preparation method of Example 2 is basically the same as that of Example 1, except that the scanning speed is set to 800 mm / s in step 3.

[0057] Example 3

[0058] The preparation method of Example 2 is basically the same as that of Example 1, except that the laser power is set to 1800W and the scanning speed is 800mm / s in step 3.

[0059] The deposited and aged samples obtained in Examples 2 and 3 were subjected to compressive superelasticity tests at room temperature. The results, combined with those of the deposited and aged samples obtained in Example 1, are presented in Table 1. The data in Table 1 show that the two heat treatments performed on the NiTiCu alloy based on directional energy deposition, as described in this invention, significantly reduce the critical stress for inducing martensitic transformation and improve its superelastic recovery rate. The minimum driving stress for inducing martensitic transformation is only 232.0 MPa, and even when the applied engineering strain is increased to a maximum strain of 8%, the alloy still maintains a high superelastic recovery rate of over 90%.

[0060] Table 1. Compression hyperelastic recovery properties of the sedimentary and aged samples from Examples 1-3

[0061]

[0062] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for producing a low driving force NiTiCu alloy based on directed energy deposition, characterized in that, Includes the following steps: S1: After fixing the NiTi alloy substrate in the forming chamber of the laser direct energy deposition equipment, the oxygen content of the atmosphere in the forming chamber is reduced to below 100ppm using high-purity circulating argon gas. S2: Set the parameters of the laser direct energy deposition equipment, and continuously deposit the dried NiTiCu pre-alloyed powder on the NiTi alloy substrate to form a preset solid model and obtain a NiTiCu alloy sample. After the NiTiCu alloy sample in the molding chamber cools to room temperature, it is taken out and cut into the target test size to obtain the deposited NiTiCu alloy sample. S3: Place the deposited NiTiCu alloy sample in a vacuum quartz tube, and then place the vacuum quartz tube in a muffle furnace at 900℃~1000℃ for 1h~2h for high-temperature solution treatment. After the high-temperature solution treatment is completed, remove the vacuum quartz tube from the muffle furnace and quickly place it in an ice-water mixture for the first quenching. S4: After the first quenching, the NiTiCu alloy sample obtained is placed in a vacuum quartz tube again, and then the vacuum quartz tube is placed in a muffle furnace at 600℃~700℃ for 2h~3h for low-temperature aging treatment. After the low-temperature aging treatment, the vacuum quartz tube is taken out of the muffle furnace and quickly placed in an ice-water mixture for a second quenching. After the second quenching, an aged NiTiCu alloy sample is obtained. The parameters of the laser direct energy deposition equipment include: laser power of 1800~2200W, scanning speed of 300mm / s~900mm / s, laser spot diameter of 3mm~5mm, and layer-to-layer overlap rate of 40~60%. When the dried NiTiCu pre-alloyed powder is deposited on the NiTi alloy substrate for the first time, a laser beam emitted by a semiconductor laser energy source is used to act on the surface of the NiTi alloy substrate to form a molten pool. Then, the dried NiTiCu pre-alloyed powder is fed into the molten pool at a feeding rate of 10~11g / min through a coaxial powder feeding nozzle under the protection of high-purity argon gas to melt and solidify on the NiTi alloy substrate to form the first NiTiCu alloy deposition layer. When the dried NiTiCu pre-alloyed powder is deposited on a NiTi alloy substrate more than once, a laser beam emitted from a semiconductor laser energy source is used to act on the surface of the previously formed NiTiCu alloy deposition layer to form a molten pool. Then, the dried NiTiCu pre-alloyed powder is simultaneously fed into the molten pool through a coaxial powder feeding nozzle under the protection of high-purity argon gas at a powder feeding rate of 10~11g / min to melt and solidify on the previously formed NiTiCu alloy deposition layer to form the current NiTiCu alloy deposition layer. In the next deposition process, the laser energy source and the powder feeding nozzle are simultaneously raised by 0.4 mm to 0.5 mm compared to the previous deposition process.

2. The method for preparing low-driving-force NiTiCu alloy based on directional energy deposition according to claim 1, characterized in that, The power of the semiconductor laser energy source is 6000W.

3. The directed energy deposition based low drive force NiTiCu alloy production method of claim 1, wherein, The drying process of NiTiCu pre-alloyed powder involves drying NiTiCu pre-alloyed powder with a particle diameter of 53μm~150μm at 110℃~130℃ and a vacuum degree of -0.08MPa~-0.1MPa for 2h~3h, and then cooling it to room temperature.

4. The method for preparing low-driving-force NiTiCu alloy based on directional energy deposition according to claim 1, characterized in that, The laser direct energy deposition equipment performs multiple continuous depositions in a reciprocating cross-grating manner.

5. The method for preparing low-driving-force NiTiCu alloy based on directional energy deposition according to claim 1, characterized in that, The internal pressure of the vacuum quartz tube is 3.5 × 10⁻⁶. -4 Pa.

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