Preparation method of supersonic speed cold spraying solid phase additive copper-based shape memory alloy

Abstract

The invention provides a preparation method of a supersonic speed cold spraying solid phase additive copper-based shape memory alloy. The method comprises the steps that dry CuZnAl powder is selected as a raw material for supersonic speed cold spraying solid phase deposition, the raw material is preheated in an inert gas atmosphere, the preheated raw material is deposited on a brass substrate through supersonic speed cold spraying solid phase additive manufacturing, and a block-shaped copper-based shape memory alloy deposition body is obtained; the preheating temperature of the raw materials is 200-350 DEG C, the pressure of inert gas during supersonic speed cold spraying solid phase additive material is 2.5-5 MPa, and the temperature of the inert gas during supersonic speed cold spraying solid phase additive material is 400-700 DEG C. According to the method, the blocky copper-based shape memory alloy is prepared through supersonic speed cold spraying solid phase additive for the first time, the temperature in the deposition process is low, volatilization of Al elements in CuZnAl powder and oxidation of powder particles are avoided, and due to strong plastic deformation of the CuZnAl powder, deposition body grains are small, and the high brittleness of the copper-based shape memory alloy is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of manufacturing metal alloy materials, and specifically to a preparation method of a supersonic cold spray solid-phase additive copper-based shape memory alloy. Background Art

[0002] Copper-based shape memory alloys have the advantages of excellent electrical / thermal conductivity, high density, high strength, high elastic modulus, high corrosion resistance, excellent superelasticity, good machinability, and low cost, and have important application prospects in the fields of aerospace, biomedicine, electronic communication, and energy chemical industry. At present, copper-based shape memory alloys have been initially applied in components such as brackets, orthotics, valves, and regulating devices. However, the phase transformation temperature of copper-based shape memory alloys is extremely susceptible to composition. Traditional melting processes are prone to cause changes in their composition, reduce phase stability, increase the stress of shape recovery, lead to phase transformation and strain recovery lag, and seriously affect their shape memory performance. In addition, the coarse grain boundaries of the samples in the traditional casting process are extremely fragile under the influence of the anisotropy of high elasticity, narrowing the plastic processing window, showing high intergranular brittleness and low fatigue strength, which greatly limits their popularization and application.

[0003] In order to reduce the high intergranular brittleness and low fatigue strength of copper-based shape memory alloys, supersonic cold spraying is used to prepare alloy materials in the prior art because the supersonic cold spraying technology can spray coatings onto the metal surface under relatively low-temperature conditions. The coating is connected to the base metal matrix through mechanical interlocking and local metallurgy. The adhesion, uniformity, and coating functionality of the coating are the core issues concerned during coating preparation. Although considering the above-mentioned core issues during coating preparation can prepare alloy materials with the best adhesion, uniformity, and coating functionality, the thickness of the prepared alloy materials is limited. However, bulk alloy materials are required for preparing components such as brackets, orthotics, valves, and regulating devices. Therefore, the alloy materials prepared by spraying coatings on the metal surface are not suitable for preparing components such as brackets, orthotics, valves, and regulating devices. When preparing components such as brackets, orthotics, valves, and regulating devices, it is required that the bulk alloy material (deposit) has higher overall mechanical properties. Therefore, how to improve the overall comprehensive mechanical properties of the copper-based shape memory alloy deposit is a key step in promoting and expanding the application of copper-based shape memory alloys. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a preparation method of a supersonic cold spray solid-phase additive copper-based shape memory alloy, aiming to solve the problems proposed in the technical background. The prepared copper-based shape memory alloy can reduce the high brittleness of the copper-based shape memory alloy and improve the comprehensive mechanical properties of the copper-based shape memory alloy.

[0005] To solve the above technical problems, the first implementation solution provided by the present invention is to provide a preparation method of a supersonic cold spray solid-phase additive copper-based shape memory alloy, which is prepared by the following preparation steps:

[0006] Select dry CuZnAl powder as the raw material for supersonic cold spray solid-phase deposition, and preheat the raw material in an inert gas atmosphere. The preheated raw material is deposited on a pre-treated brass substrate by supersonic cold spray solid-phase additive manufacturing to obtain a bulk copper-based shape memory alloy deposit;

[0007] Among them, the preheating temperature of the raw material is 200°C to 350°C, the inert gas pressure during supersonic cold spray solid-phase additive manufacturing is 2.5 MPa to 5 MPa, and the inert gas temperature during supersonic cold spray solid-phase additive manufacturing is 400°C to 700°C.

[0008] Preferably, the particle size of the CuZnAl powder is 15 μm to 53 μm.

[0009] This is because the CuZnAl powder within the particle size range of 15 μm to 53 μm can better achieve the speed required for particle deposition on the premise of ensuring the fluidity of the CuZnAl powder. When the particle size of the CuZnAl powder increases, the critical speed required for the deposition of CuZnAl powder particles increases, the deposition efficiency decreases, and the CuZnAl powder particles are not easily deposited. When the particle size of the CuZnAl powder becomes smaller, the fluidity decreases.

[0010] Preferably, the drying temperature of the CuZnAl powder is 80°C to 120°C, and the drying duration of the CuZnAl powder is 1 h to 2 h.

[0011] The powder to be dried may contain moisture or other volatile substances, which volatilize and expand during the deposition process, increasing the critical speed of powder particle deposition. As a result, under the same process conditions, the powder particles are insufficiently deformed, the coating density decreases, the porosity increases, and the grain size of the alloy material increases.

[0012] If the drying temperature of the CuZnAl powder is lower than this range, the drying purpose cannot be achieved. If the drying temperature of the CuZnAl powder is too high, it may cause oxidation of the CuZnAl powder and deteriorate the performance of the deposit.

[0013] Preferably, the weight percentage contents of the components in the CuZnAl powder are: 65 wt.% to 75 wt.% Cu, 19 wt.% to 28 wt.% Zn, and 2 wt.% to 7 wt.% Al.

[0014] Preferably, for the pretreatment of the brass substrate, the brass substrate is ultrasonically cleaned in acetone with a volume concentration of 15% to 20% at 40°C to 60°C for 10 min to 30 min, and then corundum sandblasting is carried out with 100-mesh to 300-mesh corundum. The sandblasting pressure during sandblasting is 0.2 MPa to 0.7 MPa. After sandblasting, the residual corundum sand grains on the surface of the brass substrate are blown clean with compressed air to complete the pretreatment of the brass substrate.

[0015] The pretreatment of the brass substrate can improve the bonding strength between the deposited body and the brass substrate, contribute to enhancing the bonding between the particles in the deposited body, and thus improve the density of the deposited body.

[0016] Preferably, during the supersonic cold spray solid-phase additive manufacturing, the spraying distance is 20 mm to 40 mm, the moving speed of the spray gun is 200 mm / s to 500 mm / s, and the powder feeding gas is nitrogen with a purity of 99.5% to 99.9%.

[0017] Preferably, during the supersonic cold spray solid-phase additive manufacturing, the preheated raw materials are deposited and printed in a zigzag pattern on the pretreated brass substrate. After depositing one layer, the manipulator retreats 80 μm to 200 μm.

[0018] During the supersonic cold spray solid-phase deposition process, the spraying distance is directly related to the speed of the particles. Generally, the spraying distance is 20 mm to 40 mm. After depositing one layer, the manipulator retreats 80 μm to 200 μm, mainly because the thickness of the deposited layer is usually 80 μm to 200 μm, and the retreat can ensure that the spraying distance of each layer is the same. The process parameters during the deposition process remain stable.

[0019] Preferably, the inert gas is nitrogen with a purity of 99.5% to 99.9%. Among them, the commonly used inert gas during the supersonic cold spray solid-phase additive manufacturing can be nitrogen or helium. The present invention selects nitrogen mainly considering its wide source and low price, which is suitable for industrial production.

[0020] The second implementation solution given by the present invention is to provide a preparation method for a supersonic cold spray solid-phase additive copper-based shape memory alloy to prepare a bulk copper-based shape memory alloy.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] In the preparation method of a supersonic cold spray solid-phase additive manufactured copper-based shape memory alloy provided by the present invention, the supersonic cold spray solid-phase additive manufacturing is used for the first time to prepare a bulk copper-based shape memory alloy. In the supersonic cold spray solid-phase additive manufacturing, the temperature during the deposition process is low, which avoids the volatilization of the Al element in the CuZnAl powder and the oxidation of the powder particles. The gas temperature is controlled at 400°C to 700°C to ensure that the powder particles are sufficiently softened to undergo plastic deformation and the particle temperature does not exceed its recrystallization temperature, so that the deformed particles do not recrystallize and grow on a large scale. The control of the gas pressure and temperature can make the powder particle velocity (>800 m / s) exceed its deposition critical velocity (~700 m / s). Due to the strong plastic deformation of the CuZnAl powder, the deposited body has fine grains, reducing the high brittleness of the copper-based shape memory alloy and improving its comprehensive mechanical properties.

[0023] In the preparation method of a supersonic cold spray solid-phase additive manufactured copper-based shape memory alloy provided by the present invention, preheating the CuZnAl powder can effectively compensate for the insufficient heating of the powder particles in the gas, making the particles fully softened, enhancing the plastic deformation ability of the powder particles hitting the substrate, significantly reducing the porosity of the deposited body, increasing the deposition efficiency of the powder, and improving the comprehensive properties of the deposited body.

[0024] In the preparation method of a supersonic cold spray solid-phase additive manufactured copper-based shape memory alloy provided by the present invention, the inert gas pressure during supersonic cold spray solid-phase additive manufacturing increases the gas flow velocity at the outlet of the inert gas flow, increases the velocity of the powder particles, affects the deposition efficiency, density and strength of the powder particles, and improves the comprehensive properties of the deposited body.

[0025] The method of the present invention expands the preparation process of copper-based shape memory alloys and has important application value in the manufacturing and remanufacturing of important components in fields such as aerospace, biomedicine, electronic communication, and energy chemical engineering. Description of the Drawings

[0026] Figure 1 It is a scanning electron microscope image of the microstructure of the bulk copper-based shape memory alloy deposited body in Example 9 of the present invention.

[0027] Figure 2 It is a surface image of the bulk copper-based shape memory alloy deposited body in Example 9 of the present invention. Detailed Embodiments

[0028] To make the above objects, features, and advantages of the embodiments of the present invention more apparent and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention.

[0029] The inventors found that the characteristics of high strain rate (>10 3 s-1) and low-temperature deposition in cold spraying solid-phase deposition cause severe deformation of particles, a significant increase in the dislocation density at the interface, and difficulty in grain growth, forming a nanocrystalline or submicron crystalline structure. In addition, preheating the powder can effectively soften the particles, effectively maintain the original chemical composition of the deposited body, refine the grains, improve the interlayer metallurgical bonding and overall mechanical properties of the deposited body, which is of great significance for expanding the forming process and application range of copper-based shape memory alloys.

[0030] In view of this, the present invention provides a method for preparing a supersonic cold spray solid-phase additive copper-based shape memory alloy. The prepared copper-based shape memory alloy can reduce the high brittleness of the copper-based shape memory alloy and achieve the purpose of improving the comprehensive mechanical properties of the copper-based shape memory alloy.

[0031] It should be noted that when the present invention involves a numerical range, it should be understood that both endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods adopted are the same as those in Embodiments 1 to 11, to avoid repetition, the present invention describes the preferred embodiments. However, the present invention is not limited thereto, but can also be specifically implemented in other ways within the scope of the technical solutions defined in the appended claims.

[0032] Next, the technical solutions of the present invention will be further illustrated by specific examples.

[0033] Embodiment 1

[0034] A method for preparing a supersonic cold spray solid-phase additive copper-based shape memory alloy, comprising the following steps:

[0035] Step 1: Select CuZnAl powder with an average particle size of 37 μm prepared by the gas atomization method as the raw material for supersonic cold spray solid-phase deposition. The morphology and particle size distribution of the raw material are as Figure 1 and Figure 2 shown. Before spraying, place the powder raw material in a drying furnace and dry it at 90°C for 120 min. After drying, add the raw material into the powder feeder.

[0036] Step 2: After ultrasonically cleaning the brass substrate in acetone at a temperature of 50°C and a volume fraction of 20% for 30 minutes, sandblast it with corundum having an average particle size of 300 mesh under 0.6 MPa. After sandblasting, blow off the residual corundum sand particles on the surface with compressed air to complete the pretreatment of the brass substrate, and then fix the pretreated brass substrate through a tooling.

[0037] Step 3: After the brass substrate is fixed, preheat the CuZnAl powder used as the raw material in the powder feeder at 300°C. At the same time, set the nitrogen gas pressure during supersonic cold spray solid-phase additive manufacturing to 4 MPa, the nitrogen gas temperature to 500°C, the spraying distance to 20 mm, and the gun moving speed to 300 mm / s. After setting the parameters, the preheated CuZnAl powder used as the raw material is sent out through nitrogen with a purity of 99.5% - 99.9% and deposited and printed in a zigzag pattern on the brass substrate. When depositing and printing in a zigzag pattern, the manipulator retreats 100 μm after depositing one layer to complete the deposition body of the bulk copper-based shape memory alloy.

[0038] Example 2

[0039] The difference between this example and Example 1 is that before spraying in Step 1, the CuZnAl powder raw material is placed in a drying oven and dried at 70°C for 60 minutes.

[0040] Example 3

[0041] The difference between this example and Example 1 is that before spraying in Step 1, the CuZnAl powder raw material is placed in a drying oven and dried at 120°C for 120 minutes.

[0042] Example 4

[0043] The difference between this example and Example 1 is that in Step 2, sandblasting is carried out with corundum having an average particle size of 150 mesh under 0.4 MPa.

[0044] Example 5

[0045] The difference between this example and Example 1 is that in Step 3, the preheating temperature of the CuZnAl powder is 250°C.

[0046] Example 6: The difference between this example and Example 1 is that in Step 3, the preheating temperature of the CuZnAl powder is 350°C.

[0047] Example 7

[0048] The difference between this example and Example 1 is that in Step 3, the nitrogen gas pressure during supersonic cold spray solid-phase additive manufacturing is 2.5 MPa.

[0049] Example 8

[0050] The difference between this embodiment and Embodiment 1 is that the nitrogen gas pressure during supersonic cold spray solid-phase additive manufacturing in Step 3 is 5.0 MPa.

[0051] Embodiment 9

[0052] The difference between this embodiment and Embodiment 1 is that the preheating temperature of the CuZnAl powder in Step 3 is 350 °C, the nitrogen gas pressure during supersonic cold spray solid-phase additive manufacturing is 5 MPa, and the nitrogen gas temperature during supersonic cold spray solid-phase additive manufacturing is 700 °C, where Figure 1 is the scanning electron microscope image of the microstructure of the bulk copper-based shape memory alloy deposit prepared in this embodiment. From Figure 1 it can be seen that the deposit is dense without visible pores and the deposited particles are fully deformed. Figure 2 is the surface image of the bulk copper-based shape memory alloy deposit of this embodiment.

[0053] Embodiment 10

[0054] The difference between this embodiment and Embodiment 1 is that the nitrogen gas temperature during supersonic cold spray solid-phase additive manufacturing in Step 3 is 600 °C.

[0055] Embodiment 11

[0056] The difference between this embodiment and Embodiment 1 is that the preheating temperature of the CuZnAl powder in Step 3 is 350 °C, the nitrogen gas pressure during supersonic cold spray solid-phase additive manufacturing is 5 MPa, the nitrogen gas temperature during supersonic cold spray solid-phase additive manufacturing is 700 °C, the gun moving speed is 500 mm / s, and the manipulator retreats 150 μm after depositing one layer in a Z-shaped deposition print.

[0057] Control Example 1

[0058] The difference between this control example and Embodiment 1 is that the CuZnAl powder used as the raw material for supersonic cold spray solid-phase deposition is not dried.

[0059] Control Example 2

[0060] The difference between this control example and Embodiment 1 is that the CuZnAl powder used as the raw material is not preheated in Step 3.

[0061] All of the above Embodiments 1 to 11 and Control Examples 1 to 2 can prepare bulk copper-based shape memory alloys. Now, the bulk copper-based shape memory alloy specimens deposited in Embodiment 1, Embodiment 5, Embodiment 7, Embodiment 11, and Control Examples 1 to 2 are selected for performance evaluation.

[0062] Experimental Results

[0063] 1) Density and grain size of the deposit

[0064] The deposited bulk copper-based shape memory alloy specimens of Example 1, Example 5, Example 7, Example 11 and Comparative Example 1-Comparative Example 2 were all sampled by wire cutting, and then each sample after wire cutting was polished successively with sandpapers of 180 mesh, 600 mesh, 800 mesh, 1200 mesh and 1500 mesh particle sizes. After sandpaper polishing, each sample was mirror polished. Then, a scanning electron micrograph of the microstructure of the sample after mirror polishing treatment was obtained by scanning electron microscopy, and the porosity of the scanning electron micrograph was characterized and statistically analyzed by the image method in the software ImageJ. The porosity of the coating measured by this image method is obtained by dividing the number of pixels occupied by pores by the total number of pixels of the area. During measurement, in order to ensure accuracy and reproducibility, different parts of the bulk copper-based shape memory alloy specimen need to be selected for multiple measurements and averaged. Table 1 shows the density and grain size values of the deposited bulk copper-based shape memory alloy specimens of Example 1, Example 5, Example 7, Example 11 and Comparative Example 1-Comparative Example 2.

[0065] Table 1 Density and grain size of copper-zinc-aluminum shape memory alloy with different deposition processes

[0066] Parameter Density of deposit body (%) Average grain size of deposit body (μm) Example 1 99.1±0.3 1.3 Example 5 95±0.8 2.1 Example 7 98±0.5 1.8 Example 11 99.4±0.3 1.2 Comparative Example 1 97±0.5 2.3 Comparative Example 2 92±1.2 3.8

[0067] By comparing Example 1 with Comparative Example 1 in Table 1, it can be seen that the density of the deposit in Example 1 is greater than that in Comparative Example 1, and the average grain size of the deposit in Example 1 is smaller than that in Comparative Example 1. This is because the undried CuZnAl powder may contain moisture or other volatile substances, and these substances volatilize and expand during the deposition process, increasing the critical velocity of powder particle deposition, resulting in insufficient deformation of powder particles under the same process conditions, a decrease in coating density, an increase in porosity, and an increase in average grain size.

[0068] By comparing Example 1, Example 5 and Comparative Example 2, it can be seen that when comparing Example 1 with Example 5, a decrease in the preheating temperature of the CuZnAl powder will result in a decrease in the density of the deposit and an increase in the average grain size of the deposit. When comparing Example 1, Example 5 with Comparative Example 2, the density of the deposit of the non-preheated CuZnAl powder is smaller than that of Example 1 and Example 5, and the average grain size of the deposit of the non-preheated CuZnAl powder is larger than that of Example 1 and Example 5. This is because:

[0069] Preheating the CuZnAl powder and increasing the preheating temperature of the CuZnAl powder can effectively compensate for the insufficient heating of powder particles in the gas, making the particles soften sufficiently, enhancing the plastic deformation ability of the powder to impact the substrate, significantly reducing the porosity of the deposited body, increasing the deposition efficiency of the powder, and improving the comprehensive performance of the deposited body. However, it should be noted that for easily oxidizable materials, the preheating temperature should not be too high to prevent the formation of oxides and nitrides on the surface of powder particles, which may affect the subsequent deposition of particles and the performance of the deposited body.

[0070] Comparing Example 1, Example 5, and Example 11, it can be seen that the density of the deposited body in Example 11 is greater than that in Example 1 and Example 5, and the average grain size of the deposited body in Example 11 is smaller than that in Example 1 and Example 5. The reason is as follows: The nitrogen gas pressure (the pressure of the working gas) during supersonic cold spray solid-phase additive manufacturing and the nitrogen gas temperature during supersonic cold spray solid-phase additive manufacturing are important influencing factors for supersonic cold spray solid-phase deposition. A high working gas temperature promotes the increase of the temperature of powder particles themselves, while increasing the impact velocity of particles, reducing the critical deposition velocity of particles, thereby reducing the porosity of the deposited body, improving the deposition efficiency and the strength of the deposited body. The increase in the working gas pressure increases the gas flow velocity at the outlet of the nitrogen gas flow, and the velocity of powder particles increases. In summary, the temperature and pressure of the working gas are both key parameters for supersonic cold spray solid-phase additive manufacturing, and their interaction directly affects the deposition efficiency, density, and strength of powder particles.

[0071] In the preparation method of a supersonic cold spray solid-phase additive manufacturing copper-based shape memory alloy provided by the present invention, supersonic cold spray solid-phase additive manufacturing is first used to prepare a bulk copper-based shape memory alloy. During supersonic cold spray solid-phase additive manufacturing, the deposition process temperature is low, which avoids the volatilization of Al elements in the CuZnAl powder and the oxidation of powder particles. Due to the strong plastic deformation of the CuZnAl powder, the deposited body of the prepared bulk copper-based shape memory alloy has fine grains, reducing the high brittleness of the bulk copper-based shape memory alloy and improving its comprehensive mechanical properties.

[0072] Obviously, those skilled in the art can make various changes and deformations to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and deformations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these changes and deformations.

Claims

1. A method for preparing a copper-based shape memory alloy by supersonic cold spraying solid phase additive, characterized in that: Prepared by the following preparation steps: Dry CuZnAl powder is selected as a raw material for supersonic cold spray solid phase deposition, and the raw material is preheated in an inert gas atmosphere. The preheated raw material is deposited on a pretreated brass substrate by supersonic cold spray solid phase additive manufacturing to obtain a bulk copper-based shape memory alloy deposit; Among them, the preheating temperature of the raw material is 200°C to 350°C, the inert gas pressure during supersonic cold spraying solid phase additive is 2.5MPa to 5MPa, and the inert gas temperature during supersonic cold spraying solid phase additive is 400°C to 700°C.

2. The method for preparing a copper-based shape memory alloy by supersonic cold spraying solid phase additive according to claim 1, characterized in that: The particle size of the CuZnAl powder is 15 μm to 53 μm.

3. The method for preparing a copper-based shape memory alloy by supersonic cold spraying solid phase additive according to claim 1, characterized in that: The drying temperature of the CuZnAl powder is 80° C. to 120° C., and the drying time of the CuZnAl powder is 1 h to 2 h.

4. The method for preparing a copper-based shape memory alloy by supersonic cold spraying solid phase additive according to claim 1, characterized in that: The weight percentage of each component in the CuZnAl powder is: 65wt.%-75wt.% Cu, 19wt.%-28wt.% Zn and 2wt.%-7wt.% Al.

5. The method for preparing a copper-based shape memory alloy by supersonic cold spraying solid phase additive according to claim 1, characterized in that: The brass substrate pretreatment is to ultrasonically clean the brass substrate with acetone having a volume concentration of 15% to 20% at 40°C to 60°C for 10min to 30min, and then sandblast with 100-300-mesh corundum. The sandblasting pressure during sandblasting is 0.2MPa to 0.7MPa. After sandblasting, the corundum sand remaining on the surface of the brass substrate is blown away with compressed air to complete the pretreatment of the brass substrate.

6. The method for preparing a copper-based shape memory alloy by supersonic cold spraying solid phase additive according to claim 1, characterized in that: The spraying distance during supersonic cold spray solid phase additive manufacturing is 20mm-40mm, the movement speed of the spray gun during supersonic cold spray solid phase additive manufacturing is 200mm / s-500mm / s, and the powder feeding gas during supersonic cold spray solid phase additive manufacturing is nitrogen with a purity of 99.5%-99.9%.

7. The method for preparing a copper-based shape memory alloy by supersonic cold spraying solid phase additive according to claim 6, characterized in that: During the supersonic cold spray solid phase additive manufacturing, the preheated raw material is deposited and printed in a zigzag pattern on a pretreated brass substrate.

8. The method for preparing a copper-based shape memory alloy by supersonic cold spraying solid phase additive according to claim 1, characterized in that: The inert gas is nitrogen with a purity of 99.5% to 99.9%.

9. A bulk copper-based shape memory alloy prepared by the method for supersonic cold spraying solid phase additive manufacturing of copper-based shape memory alloy according to any one of claims 1 to 8.

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