Method for preparing NiTiFe alloy with low elastic modulus based on additive manufacturing

Abstract

The invention relates to the technical field of additive manufacturing, in particular to a method for preparing a NiTiFe alloy with low elastic modulus based on additive manufacturing. According to the method, additive manufacturing is conducted on target metal powder on the basis of the forming principle of layer-by-layer superposition of additive manufacturing, and compared with a traditional metallurgical technology, excellent surface quality and geometric accuracy can be provided, and intelligent integrated forming of complex workpieces can be rapidly achieved; through the set raw material ratio, the critical defect concentration appearing at the low elastic modulus in the material can be met, Fe atoms can also serve as heterogeneous nucleating agents, a unique fine grain structure can be formed in the non-equilibrium solidification process under appropriate forming parameters, the mechanical performance of the material is greatly improved, and the advantage that the material characteristics are cooperatively considered is achieved; atomic relaxation generated after the Fe element is added into NiTi not only can generate point defects required by low elastic modulus, but also can generate dislocation, precipitation phase and other multi-dimensional defects at a matrix and a grain boundary.

Description

Technical Field

[0001] The present invention relates to the technical field of additive manufacturing, and in particular to a method for preparing a NiTiFe alloy with a low elastic modulus based on additive manufacturing. Background Art

[0002] Nickel-titanium-based shape memory alloys are gaining increasing attention in the aerospace, defense, biomedical and automotive industries due to their unique functional properties (such as shape memory effect and superelasticity), biocompatibility and corrosion resistance. However, due to the limitations of their inherent transformation characteristics, binary nickel-titanium alloys cannot meet the requirements of some special applications. Among the many shape memory alloy materials, NiTiFe alloy has broad application prospects in industrial couplings, aerospace buffers and cryogenic refrigeration due to its excellent shape memory effect.

[0003] However, for industry scenarios such as flexible robots and aerospace buffers, NiTiFe alloys have difficulty solving the problem of coexistence of strength (i.e., larger yield limit) and flexibility (i.e., lower elastic modulus).

[0004] Based on this, there is an urgent need for a method for preparing NiTiFe alloy with low elastic modulus based on additive manufacturing to solve the above technical problems. Summary of the invention

[0005] The present invention provides a method for preparing a NiTiFe alloy with a low elastic modulus based on additive manufacturing, which can solve the problem of coexistence of strength and flexibility.

[0006] An embodiment of the present invention provides a method for preparing a NiTiFe alloy with a low elastic modulus based on additive manufacturing, comprising:

[0007] Obtaining target metal powder; wherein the target metal powder includes pure Fe powder and pre-alloyed NiTi powder;

[0008] The target metal powder is additively manufactured to obtain a NiTiFe alloy with a low elastic modulus; wherein the value range of the low elastic modulus is 13 to 14 GPa, and the yield limit of the NiTiFe alloy is 700 to 800 MPa.

[0009] It can be seen from the above scheme that the method for preparing NiTiFe alloy with low elastic modulus based on additive manufacturing provided by the present invention is to perform additive manufacturing on the target metal powder by forming principle based on additive manufacturing layer by layer. Compared with traditional metallurgical technology, it can not only provide excellent surface quality and geometric accuracy, but also can quickly realize intelligent integrated forming of complex workpieces, and the economic cost is much lower than the traditional process, and the production efficiency is significantly improved; further, by setting the raw material ratio, not only the critical defect concentration of low elastic modulus inside the material can be met, but Fe atoms can also be used as heterogeneous nucleating agents, which will form a unique fine-grained structure in the non-equilibrium solidification process under appropriate forming parameters, greatly improving the mechanical properties of the material, and playing the role of synergistic consideration of material properties; the atomic relaxation generated after the Fe element is added to NiTi can not only produce point defects required to meet the low elastic modulus, but also dislocations and precipitations in the matrix and grain boundaries. Equal multidimensional defects. Therefore, the above technical scheme can achieve precise control of the chemical composition and defect concentration inside the alloy to achieve the critical defect concentration of low elastic modulus. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0011] Figure 1 A schematic flow chart of a method for preparing a NiTiFe alloy with a low elastic modulus based on additive manufacturing provided in an embodiment of the present invention;

[0012] Figure 2 A schematic diagram of the relevant characterization of a target metal powder provided by an embodiment of the present invention;

[0013] Figure 3 EBSD schematic diagram of the NiTiFe alloy with low elastic modulus prepared in an embodiment of the present invention;

[0014] Figure 4 This is a TEM micrograph of a NiTiFe alloy with a low elastic modulus prepared in an embodiment of the present invention;

[0015] Figure 5 This is a schematic diagram of the low elastic modulus at the atomic level in the NiTiFe alloy with low elastic modulus prepared in an embodiment of the present invention;

[0016] Figure 6A stress-strain curve diagram of 1 to 30 superelastic cycles in a NiTiFe alloy with a low elastic modulus prepared according to an embodiment of the present invention;

[0017] Figure 7 A stress-strain curve diagram of the NiTiFe alloy with a low elastic modulus prepared in Example 1 of the present invention;

[0018] Figure 8 This is a stress-strain curve diagram of the NiTiFe alloy with low elastic modulus prepared in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0020] See also Figure 1 , an embodiment of the present invention provides a method for preparing a NiTiFe alloy with a low elastic modulus based on additive manufacturing, the method comprising:

[0021] Step S1, obtaining target metal powder; wherein the target metal powder includes pure Fe powder and pre-alloyed NiTi powder;

[0022] Step S2, performing additive manufacturing on the target metal powder to obtain a NiTiFe alloy with a low elastic modulus; wherein the value range of the low elastic modulus is 13 to 14 GPa, and the yield limit of the NiTiFe alloy is 700 to 800 MPa.

[0023] In this embodiment, additive manufacturing is performed on the target metal powder by the forming principle of layer-by-layer stacking based on additive manufacturing. Compared with traditional metallurgical technology, it can not only provide excellent surface quality and geometric accuracy, but also quickly realize the intelligent integrated forming of complex workpieces, and the economic cost is much lower than the traditional process, and the production efficiency is significantly improved; further, the set raw material ratio can not only meet the critical defect concentration of low elastic modulus inside the material, but Fe atoms can also be used as heterogeneous nucleating agents, which will form a unique fine-grained structure in the non-equilibrium solidification process under appropriate forming parameters, greatly improving the mechanical properties of the material, and playing the role of synergistic consideration of material properties; the atomic relaxation generated by the addition of Fe elements to NiTi can not only produce point defects required to produce low elastic modulus, but also produce multidimensional defects such as dislocations and precipitation in the matrix and grain boundaries. Therefore, the above technical scheme can achieve precise control of the chemical composition and defect concentration inside the alloy to achieve the critical defect concentration of low elastic modulus.

[0024] In one embodiment of the present invention, the pure Fe powder accounts for 2-4% of the total mass of the target metal powder.

[0025] In one embodiment of the present invention, the pure Fe powder accounts for 3% of the total mass of the target metal powder.

[0026] During the experiment, the inventors found that when pure Fe powder accounts for 2-4% of the total mass of the target metal powder, the critical defect concentration that can meet the occurrence of low elastic modulus inside the material can be achieved, and when pure Fe powder accounts for 3% of the total mass of the target metal powder, this low elastic modulus is more intuitive and clear.

[0027] In one embodiment of the present invention, the particle size of the pure Fe powder is 90-110 nm, and the particle size of the NiTi powder is 15-53 μm.

[0028] In one embodiment of the present invention, additive manufacturing is performed on a target metal powder to obtain a NiTiFe alloy having a low elastic modulus, comprising:

[0029] Construct a three-dimensional model of the structure of the desired part, and input the three-dimensional model into the 3D printing editing software, so as to use the 3D printing editing software to perform two-dimensional processing on the three-dimensional model to obtain two-dimensional slice data;

[0030] Input the 2D slice data into the metal powder laser melting system;

[0031] Set the processing parameters of the metal powder laser melting system;

[0032] Spreading the target metal powder on the bottom plate of the metal powder laser melting system, and introducing an inert gas into the metal powder laser melting system;

[0033] The target metal powder on the base plate is additively manufactured using a metal powder laser melting system to obtain a NiTiFe alloy with a low elastic modulus.

[0034] In one embodiment of the present invention, the processing parameters include laser power, scanning speed, scanning spacing, powder layer thickness, spot diameter and preheating temperature of the base plate.

[0035] In one embodiment of the present invention, the laser power is 80-140W, the scanning speed is 150-300mm / s, the scanning spacing is 70-90μm, the powder layer thickness is 25-35μm, the spot diameter is 60-80μm, and the preheating temperature is 90-110° C. Such settings can ensure that the target metal powder with a higher melting point can smoothly form a liquid phase.

[0036] In this embodiment, the above-mentioned additive manufacturing technology has a unique non-equilibrium solidification mechanism, that is, in the process of liquid crystallization and solid precipitation, due to the excessively fast cooling rate, the solid molecules precipitated in the liquid diffuse unevenly, resulting in uneven concentrations of solid molecules in the crystallization. When the temperature drops to the solidus, there is still a phenomenon of non-uniform crystallization of the liquid phase. Therefore, this method ensures that when preparing NiTiFe alloy, line defects (i.e., dislocations) and surface defects (i.e., precipitated phases) can be generated inside in addition to point defects. This coupling of multiple defects is considered to be a necessary condition for the expansion of new low elastic modulus materials.

[0037] In one embodiment of the present invention, after the inert gas is introduced, the oxygen and water vapor content in the metal powder laser melting system are both less than 10 ppm. This arrangement can prevent the process parts (i.e., NiTiFe alloy) from being oxidized during the forming process, which would affect the quality of the finished product.

[0038] In one embodiment of the present invention, the target metal powder on the base plate is additively manufactured by:

[0039] Laser melting, powder sieving, heat treatment, wire cutting, cleaning and polishing.

[0040] It is known that the metal powder laser melting system needs to be cleaned before use to prevent other ingredients from mixing in and affecting product quality. After loading the powder, calibrate the work platform to prevent errors from affecting product performance. After calibrating the work platform, fill with argon → spread powder → laser pre-melting → re-spread powder → laser melting → re-spread powder → laser re-melting → end. The next step is to screen the powder. The purpose of screening the powder is to prevent the removal of small particles. Generally, a sieve with a specified aperture is used for screening to remove small particles and prevent them from affecting the performance of subsequent product processing.

[0041] In some embodiments, in order to ensure that the molded product is firmly bonded to the bottom, 2-5 layers are melted in the pre-scanning. In addition, the number of subsequent laser melting powder layers is determined according to the size of the workpiece. The larger the workpiece, the more powder layers are needed.

[0042] In one embodiment of the present invention, ultrasonic cleaning is used for cleaning, the cleaning time is 0.5 to 1 hour, and the cleaning medium is anhydrous alcohol.

[0043] In this embodiment, ultrasonic cleaning is adopted to utilize the cavitation effect, acceleration effect and direct current effect of ultrasonic waves in liquid to directly and indirectly affect liquid and dirt, so that the dirt layer is dispersed, emulsified and peeled off to achieve the cleaning purpose, and the cleaning is more thorough. In addition, the cleaning medium adopted is anhydrous alcohol, which is easy to evaporate after cleaning and leaves no residue on the cleaned object.

[0044] Combine the following Figures 2 to 6 to explain.

[0045] Figure 2 1 is a relevant characterization of the mixed powder raw material in the embodiment of the present invention, wherein: (a) electron microscope morphology of NiTi powder; (b) electron microscope morphology of pure Fe powder; (c) electron microscope morphology of NiTiFe powder; (d) room temperature XRD diagram of NiTi and Fe powder; Figure 2 The powder scanning electron microscope image of the middle ac shows the specific morphology of the powder raw materials used in the embodiment of the present invention, which are spherical pre-alloyed NiTi powder with a particle size of 15 to 53 μm, spherical Fe powder with a size of 90 to 110 nm, and mixed powder. It can be seen that the surface of all powders is smooth, and the Fe powder is evenly distributed on the surface of the NiTi powder without obvious agglomeration. Figure 2 d is the phase composition of NiTi and Fe powders obtained by X-ray diffractometer (XRD) at room temperature. The results show that the primary phase of NiTi powder is B2 phase, Fe powder is α-Fe phase, and no other impurities and secondary phases are detected in the sample.

[0046] Figure 3 EBSD diagram of the NiTiFe alloy prepared in the embodiment of the present invention; the figure shows that the elongated columnar grains grow in the form of stretching and extension along the parallel construction direction. The non-equilibrium solidification process in the LPBF process produces heterogeneous nucleation of Fe elements, resulting in grain refinement, which greatly improves the mechanical properties of the NiTiFe alloy.

[0047] Figure 4 3 is a TEM micrograph of the NiTiFe alloy prepared in accordance with an embodiment of the present invention; the non-equilibrium solidification microstructure produced by the additive manufacturing process, such as dislocations and precipitation phases, can be clearly seen in the figure, which is a necessary condition for realizing additive manufacturing to prepare NiTiFe with low elastic modulus.

[0048] Figure 5 It is a principle diagram of low elastic modulus at the atomic level in the NiTiFe alloy prepared in an embodiment of the present invention; it can be seen that under the influence of factors such as Fe element, dislocation and precipitation phase, the process parameter conditions can achieve the generation of low elastic modulus nanodomain structure.

[0049] Figure 6 is a stress-strain curve of 1 to 30 superelastic cycles in the NiTiFe alloy prepared in the embodiment of the present invention, Figure 6 It can be seen that after multiple superelastic cycles, the NiTiFe alloy prepared under this process parameter exhibits extremely large recoverable strain and extremely narrow strain hysteresis.

[0050] Figure 7 is a stress-strain curve diagram of the NiTiFe alloy prepared in Example 1 of the present invention, Figure 7 It can be seen that: this is the stress-strain curve in Example 1. It can be seen from the figure that the yield limit of NiTiFe prepared by LPBF is 752MPa, and the strain required when loaded to the yield limit is 5.5%. The calculated elastic modulus of the alloy is 13.7GPa, which is much lower than the elastic modulus of conventional metals such as Al and Cu and other soft metals (70GPa and 115GPa).

[0051] Figure 8 is a stress-strain curve of the NiTiFe alloy prepared in Comparative Example 1 of the present invention, Figure 8 It can be seen that: from the stress-strain curve in comparative example 1, the yield limit of NiTiFe prepared by LPBF is 783MPa, and the strain required to load to the yield limit is 5.3%. The calculated elastic modulus of the alloy is 14.7Gpa, which is much lower than the elastic modulus of conventional metals such as Al and Cu.

[0052] It can be known that the extremely low elastic modulus of NiTiFe alloy enables the material to withstand mechanical deformation such as bending and folding without losing its function during use. This means that the NiTiFe alloy in this patent not only has a large yield limit but can also drive the material to deform under very small stress. This overcomes the long-standing material problem of strength-flexibility coexistence. This has great application potential in flexible robots and aerospace cushioning industries. This high-strength alloy may open the door to the widespread application of emerging technologies such as deformable spacecraft, humanoid robots and advanced biomedical equipment.

[0053] Specific examples and comparative examples are described below. Specific embodiment 1

[0055] (a) Using pure Fe powder and pre-alloyed NiTi powder as raw materials, wherein the Fe powder has a particle size of 90 to 110 nm, the NiTi powder has a particle size distribution of 15 to 53 μm, the pure Fe powder accounts for 3% of the total mass of the target metal powder, and the remaining components are all NiTi, and preparing NiTiFe alloy powder by using a high-energy planetary ball milling method;

[0056] (b) Construct a 3D model of the required part structure and input it into the 3D printing editing software, pre-build a block with a size of 5×5×8mm, and set the long side direction parallel to the printing direction. After editing, perform two-dimensional processing to obtain two-dimensional slice data and import it into the metal powder laser melting system;

[0057] (c) Setting the processing parameters of the metal powder laser melting system: laser power is 110 W, scanning speed is 200 mm / s, powder layer thickness is set to 30 μm by the system, scanning interval is fixed to 80 μm, and base plate preheating temperature is 100 °C;

[0058] (d) spreading NiTiFe powder on a bottom plate of a metal powder laser melting system, introducing inert gas argon into the metal powder laser melting system until the oxygen content in the molding chamber is below 10 ppm, and starting additive manufacturing;

[0059] (e) After the additive process stops, the printed workpiece is cut by wire to obtain the sample.

[0060] Comparative Example 1

[0061] Comparative Example 1 is substantially the same as Example 1, except that the NiTiFe alloy is prepared by using process parameters of a laser power of 70 W, a scanning speed of 310 mm / s, a powder layer thickness of 30 μm, and a scanning interval of 80 μm.

[0062] The prepared NiTiFe alloy has serious unfused defects on its surface, a large number of cracks on the surface, and the complete forming of the NiTiFe alloy cannot be achieved, and a low elastic modulus does not appear.

[0063] Comparative Example 2

[0064] Comparative Example 2 is substantially the same as Example 1, except that the NiTiFe alloy is prepared by using process parameters of a laser power of 150 W, a scanning speed of 140 mm / s, a powder layer thickness of 30 μm, and a scanning interval of 80 μm.

[0065] The surface roughness of the prepared NiTiFe alloy was severely reduced and element burnout occurred, resulting in extremely poor forming quality without the occurrence of low elastic modulus.

[0066] Comparative Example 3

[0067] Comparative Example 3 is substantially the same as Example 1, except that the NiTiFe alloy is prepared by using process parameters of a laser power of 150 W, a scanning speed of 310 mm / s, a powder layer thickness of 30 μm, and a scanning interval of 80 μm.

[0068] The surface roughness of the prepared NiTiFe alloy was severely reduced and element burnout occurred, resulting in extremely poor forming quality without the occurrence of low elastic modulus.

[0069] Comparative Example 4

[0070] Comparative Example 4 is substantially the same as Example 1, except that the NiTiFe alloy is prepared by using process parameters of 70 W laser power, 140 mm / s scanning speed, 30 μm powder layer thickness and 80 μm scanning spacing.

[0071] The prepared NiTiFe alloy has good surface quality, but still does not have a low elastic modulus. Specific embodiment 2

[0073] (a) Using pure Fe powder and pre-alloyed NiTi powder as raw materials, wherein the Fe powder has a particle size of 90 to 110 nm, the NiTi powder has a particle size distribution of 15 to 53 μm, the pure Fe powder accounts for 2% of the total mass of the target metal powder, and the remaining components are all NiTi, and preparing NiTiFe alloy powder by using a high-energy planetary ball milling method;

[0074] (b) Construct a 3D model of the required part structure and input it into the 3D printing editing software, pre-build a block with a size of 5×5×8mm, and set the long side direction parallel to the printing direction. After editing, perform two-dimensional processing to obtain two-dimensional slice data and import it into the metal powder laser melting system;

[0075] (c) Setting the processing parameters of the metal powder laser melting system: laser power is 120 W, scanning speed is 220 mm / s, powder layer thickness is set to 30 μm by the system, scanning interval is fixed to 80 μm, and base plate preheating temperature is 100 °C;

[0076] (d) spreading NiTiFe powder on a bottom plate of a metal powder laser melting system, introducing inert gas argon into the metal powder laser melting system until the oxygen content in the molding chamber is below 10 ppm, and starting additive manufacturing;

[0077] (e) After the additive process stops, the printed workpiece is cut by wire to obtain the sample. Specific embodiment 3

[0079] (a) Using pure Fe powder and pre-alloyed NiTi powder as raw materials, wherein the Fe powder has a particle size of 90 to 110 nm, the NiTi powder has a particle size distribution of 15 to 53 μm, the pure Fe powder accounts for 2% of the total mass of the target metal powder, and the remaining components are all NiTi, and preparing NiTiFe alloy powder by using a high-energy planetary ball milling method;

[0080] (b) Construct a 3D model of the required part structure and input it into the 3D printing editing software, pre-build a block with a size of 5×5×8mm, and set the long side direction parallel to the printing direction. After editing, perform two-dimensional processing to obtain two-dimensional slice data and import it into the metal powder laser melting system;

[0081] (c) Setting the processing parameters of the metal powder laser melting system: laser power is 110 W, scanning speed is 180 mm / s, powder layer thickness is set to 30 μm by the system, scanning interval is fixed to 80 μm, and base plate preheating temperature is 100 °C;

[0082] (d) spreading NiTiFe powder on a bottom plate of a metal powder laser melting system, introducing inert gas argon into the metal powder laser melting system until the oxygen content in the molding chamber is below 10 ppm, and starting additive manufacturing;

[0083] (e) After the additive process stops, the printed workpiece is cut by wire to obtain the sample. Specific embodiment 4

[0085] (a) Using pure Fe powder and pre-alloyed NiTi powder as raw materials, wherein the Fe powder has a particle size of 90 to 110 nm, the NiTi powder has a particle size distribution of 15 to 53 μm, the pure Fe powder accounts for 4% of the total mass of the target metal powder, and the remaining components are NiTi, and preparing NiTiFe alloy powder by using a high-energy planetary ball milling method;

[0086] (b) Construct a 3D model of the required part structure and input it into the 3D printing editing software, pre-build a block with a size of 5×5×8mm, and set the long side direction parallel to the printing direction. After editing, perform two-dimensional processing to obtain two-dimensional slice data and import it into the metal powder laser melting system;

[0087] (c) Setting the processing parameters of the metal powder laser melting system: laser power is 100 W, scanning speed is 220 mm / s, powder layer thickness is set to 30 μm by the system, scanning interval is fixed to 80 μm, and base plate preheating temperature is 100 °C;

[0088] (d) spreading NiTiFe powder on a bottom plate of a metal powder laser melting system, introducing inert gas argon into the metal powder laser melting system until the oxygen content in the molding chamber is below 10 ppm, and starting additive manufacturing;

[0089] (e) After the additive process stops, the printed workpiece is cut by wire to obtain the sample. Specific embodiment 5

[0091] (a) Using pure Fe powder and pre-alloyed NiTi powder as raw materials, wherein the Fe powder has a particle size of 90 to 110 nm, the NiTi powder has a particle size distribution of 15 to 53 μm, the pure Fe powder accounts for 4% of the total mass of the target metal powder, and the remaining components are NiTi, and preparing NiTiFe alloy powder by using a high-energy planetary ball milling method;

[0092] (b) Construct a 3D model of the required part structure and input it into the 3D printing editing software, pre-build a block with a size of 5×5×8mm, and set the long side direction parallel to the printing direction. After editing, perform two-dimensional processing to obtain two-dimensional slice data and import it into the metal powder laser melting system;

[0093] (c) Setting the processing parameters of the metal powder laser melting system: laser power is 140 W, scanning speed is 200 mm / s, powder layer thickness is set to 30 μm by the system, scanning interval is fixed to 80 μm, and base plate preheating temperature is 100 °C;

[0094] (d) spreading NiTiFe powder on a bottom plate of a metal powder laser melting system, introducing inert gas argon into the metal powder laser melting system until the oxygen content in the molding chamber is below 10 ppm, and starting additive manufacturing;

[0095] (e) After the additive process stops, the printed workpiece is cut by wire to obtain the sample.

[0096] It should be noted that, in the present invention, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0097] Finally, it should be noted that the above is only a preferred embodiment of the present invention, which is only used to illustrate the technical solution of the present invention, and is not used to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A method for preparing a NiTiFe alloy with a low elastic modulus based on additive manufacturing, characterized in that: include: Obtaining target metal powder; wherein the target metal powder includes pure Fe powder and pre-alloyed NiTi powder; The target metal powder is additively manufactured to obtain a NiTiFe alloy with a low elastic modulus; wherein the value range of the low elastic modulus is 13 to 14 GPa, and the yield limit of the NiTiFe alloy is 700 to 800 MPa.

2. The method according to claim 1, characterized in that The pure Fe powder accounts for 2-4% of the total mass of the target metal powder.

3. The method according to claim 2, characterized in that The pure Fe powder accounts for 3% of the total mass of the target metal powder.

4. The method according to claim 1, characterized in that The particle size of the pure Fe powder is 90-110 nm, and the particle size of the NiTi powder is 15-53 μm.

5. The method according to any one of claims 1 to 4, characterized in that The method of additively manufacturing the target metal powder to obtain a NiTiFe alloy with a low elastic modulus comprises: Constructing a three-dimensional model of the structure of the part to be prepared, and inputting the three-dimensional model into a 3D printing editing software, so as to perform two-dimensional processing on the three-dimensional model using the 3D printing editing software to obtain two-dimensional slice data; Inputting the two-dimensional slice data into a metal powder laser melting system; Setting processing parameters of the metal powder laser melting system; Spreading the target metal powder on the bottom plate of the metal powder laser melting system, and introducing an inert gas into the metal powder laser melting system; The target metal powder on the base plate is additively manufactured using the metal powder laser melting system to obtain a NiTiFe alloy with a low elastic modulus.

6. The method according to claim 5, characterized in that The processing parameters include laser power, scanning speed, scanning spacing, powder layer thickness, spot diameter and preheating temperature of the base plate.

7. The method according to claim 6, characterized in that The laser power is 80-140W, the scanning speed is 150-300mm / s, the scanning interval is 70-90μm, the powder layer thickness is 25-35μm, the spot diameter is 60-80μm, and the preheating temperature is 90-110°C.

8. The method according to claim 5, characterized in that After the inert gas is introduced, the contents of oxygen and water vapor in the metal powder laser melting system are both lower than 10 ppm.

9. The method according to claim 5, characterized in that The target metal powder on the base plate is additively manufactured by: Laser melting, powder sieving, heat treatment, wire cutting, cleaning and polishing.

10. The method according to claim 9, characterized in that The cleaning is carried out by ultrasonic cleaning, the cleaning time is 0.5 to 1 hour, and the cleaning medium is anhydrous alcohol.

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