Super-elastic nickel-titanium alloy wire with high super-elastic stress and large plasticity, and preparation method and application thereof

Abstract

This invention relates to the field of superelastic nickel-titanium alloy wire processing technology, specifically to a superelastic nickel-titanium alloy wire possessing both high superelasticity and high plasticity, its preparation method, and its applications. Addressing the technical bottlenecks of traditional low-nickel-rich NiTi alloys, this invention develops a novel superelastic NiTi alloy wire. By employing a high-nickel composition (Ni content of 51.5 at.%~52.5 at.%) and implementing ultra-large cold deformation (cold drawing deformation ≥65%), the alloy achieves amorphization. Subsequently, a micron-scale coarse NiTi grains are obtained through an ultra-short-time electric annealing process (electricity time ≤0.5s), followed by low-temperature aging treatment to form a locally chemically ordered structure with a size of 1nm~4nm internally. This method controls a novel microstructure, enabling the superelastic nickel-titanium alloy wire to maintain excellent superelasticity while also possessing high superelastic plateau stress and high elongation.

Description

Technical Field

[0001] This invention relates to the field of ultraelastic nickel-titanium alloy wire processing technology, specifically to an ultraelastic nickel-titanium alloy wire with both high elasticity and high plasticity, its preparation method, and its application. Background Technology

[0002] Due to its unique superelasticity and shape memory effect, NiTi alloys have been widely used in biomedicine, aerospace, microelectronics, and precision instruments. Superelastic NiTi alloy wires are commonly used in key components such as guidewires, vascular stents, flexible connectors, and actuation elements. These applications require materials to simultaneously possess high recoverable strain, high superelastic stress, and excellent plastic deformation capacity (large elongation at break) to meet the mechanical performance requirements under complex service environments.

[0003] Currently, commercially available superelastic NiTi alloy wires are mostly designed with low nickel content, with Ni atomic percentage typically ranging from 50.6 at.% to 51.0 at.%. A typical manufacturing process involves cold-drawing a hot-worked billet by 40% to 50%, followed by annealing at 450°C to 550°C. The resulting microstructure consists of submicron-scale NiTi matrix grains and nanoscale Ni4Ti3 precipitates, which endow the material with excellent superelastic properties and cycle stability.

[0004] However, the aforementioned traditional technical routes suffer from significant performance bottlenecks in practical applications. On the one hand, the hyperelastic plateau stress of the materials is typically below 600 MPa, making it difficult to meet the high hyperelastic stress requirements of specific applications such as high-drive-stress devices, high-load connectors, and high-stress medical devices. On the other hand, their tensile elongation at break is typically less than 20%, making the materials prone to fracture under extreme service conditions requiring large plastic deformation or complex bending and torsion. In summary, the traditional low-nickel-rich NiTi alloy (Ni≤51.0 at.%) combined with 40%~50% cold deformation and annealing at 450℃~550℃ cannot simultaneously achieve high hyperelastic plateau stress (>700 MPa) and large plastic deformation capacity (elongation at break >20%). This fundamental technical problem of insufficient synergy between "high hyperelastic stress-large plasticity-hyperelasticity" severely restricts its application in higher-performance fields. Summary of the Invention

[0005] The purpose of this invention is to overcome the technical shortcomings of traditional hyperelastic nickel-titanium alloy wires, which struggle to simultaneously achieve high hyperelasticity, high plateau stress, and high elongation. This invention provides a hyperelastic nickel-titanium alloy wire combining high hyperelasticity and high plasticity, along with its preparation method and applications. It is a method for preparing nickel-rich nickel-titanium alloy wires using electropulse crystallization-low-temperature aging. This method, through a unique combination of compositional design and cold drawing deformation and heat treatment processes, regulates a novel microstructure, enabling the hyperelastic nickel-titanium alloy wire to achieve excellent comprehensive mechanical properties, ensuring both superior hyperelasticity and high plateau stress and high elongation.

[0006] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution: This invention protects a method for preparing a superelastic nickel-titanium alloy wire that combines high elasticity and high plasticity, comprising the following steps: Using hot-drawn nickel-titanium alloy wire as raw material, the chemical composition of the nickel-titanium alloy wire is Ni a Ti 100-a Where 51.5 ≤ a ≤ 52.5, a is the atomic percentage, that is, the atomic percentage of Ni is a%, and the atomic percentage of Ti is (100-a)%; when a is lower than 51.5, the superelastic stress is lower, and Ni... 51 Ti 49 Comparative experiments show that, under the same parameters, the platform stress is about 400 MPa lower; if a is higher than 52.5, the wire's deformation capacity decreases, and it cannot undergo large cold drawing deformation at room temperature, resulting in cold drawing brittle fracture.

[0007] First, the raw material undergoes high-temperature solution annealing, followed by cold drawing deformation at room temperature with a deformation amount ≥65%, achieving alloy amorphization. After severe cold deformation, it transforms into a mixed structure of nanocrystalline and amorphous materials, yielding wire. The wire is predominantly amorphous with a small amount of nanocrystalline structure. If the deformation amount is <65%, the structure cannot be completely amorphized, and subsequent annealing only results in dislocation recovery and recrystallization. The structure obtained from amorphous crystallization has two advantages: firstly, it has very few intragranular defects, making it less likely to become a crack initiation source during stretching, thus ensuring good plasticity; secondly, the grain size is relatively uniform.

[0008] Short-time electrical pulse crystallization treatment was applied to the wire to obtain electrical pulse crystallized wire, which caused the amorphous structure to crystallize rapidly and suppressed the diffusion of Ni atoms, forming a single austenitic B2 phase with a grain size of 1μm~4μm.

[0009] Low-temperature aging treatment of electrically pulsed crystallized wires creates a locally chemically ordered structure rich in nickel without altering the grain size of the treated wire. This locally chemically ordered structure refers to the non-random, preferential arrangement of atoms of different elements within a micro-region of sub-nanometer to several nanometers in a macroscopically homogeneous solid solution (nearest neighbor atoms tend to attract or repel each other), without forming long-range periodicity or being a precipitated phase. The locally chemically ordered structure accounts for 30% to 40% of the structure. This structure differs from the common Ni4Ti3 precipitate and has a size of 1 nm to 4 nm, resulting in a superelastic nickel-titanium alloy wire that combines high elasticity and high plasticity.

[0010] Preferably, the diameter of the raw material is 0.2mm to 2mm. If the raw material is coarser, it can be treated by repeated solution treatment at 750℃ and cold drawing several times. However, attention should be paid to the diameter during the last solution treatment to ensure that the final cold deformation amount reaches more than 65%.

[0011] Preferably, the conditions for high-temperature solution annealing are: holding at 750℃~800℃ for 20min~40min.

[0012] Preferably, the diameter of the wire is 0.1mm to 1.0mm.

[0013] Preferably, the electrical pulse parameters for short-time electrical pulse crystallization treatment are: AC voltage 10V~50V, single pulse conduction time 0.2ms~0.5ms, pulse on / off ratio 1:7, total conduction time ≤0.5s, and heating temperature 750℃~850℃.

[0014] Preferably, the low-temperature aging treatment conditions are: treatment at 200℃~250℃ for 10h~50h.

[0015] This invention also protects a superelastic nickel-titanium alloy wire that combines high elasticity and high plasticity, which is prepared by the above-described method.

[0016] Preferably, the microstructure of the superelastic nickel-titanium alloy wire with both high elasticity and high plasticity is: a single B2 phase austenite grain with a size of 1μm~4μm, and a nickel-rich local chemically ordered structure with a size of 1nm~4nm dispersedly distributed inside the B2 phase austenite grain.

[0017] Preferably, the superelastic nickel-titanium alloy wire with both high superelastic stress and high plasticity has a superelastic stress > 900 MPa, a superelastic strain ≥ 8%, and a total elongation > 60%.

[0018] This invention also protects the application of superelastic nickel-titanium alloy wires, which combine high elasticity and high plasticity, in the preparation of guidewires, vascular stents, flexible connectors, and drive elements.

[0019] Compared with the prior art described above, the beneficial effects of the present invention are as follows: 1. To address the technical bottlenecks of traditional low-nickel-rich NiTi alloys, this invention develops a novel superelastic NiTi alloy wire. The technical approach of this invention differs significantly from conventional methods. Specifically, by employing a high-nickel composition (Ni content of 51.5 at.%~52.5 at.%) and implementing ultra-large cold deformation (cold drawing deformation ≥65%), the alloy achieves amorphization. Subsequently, a micron-scale coarse NiTi grains are obtained through an ultra-short-time electric annealing process (electricity application time ≤0.5s). Following low-temperature aging treatment, a locally chemically ordered structure with a size of 1nm~4nm is formed within the material. Experiments show that the NiTi alloy wire prepared using this method simultaneously possesses high superelastic plateau stress, large fracture strain (>60%), and excellent superelasticity, effectively solving the performance bottlenecks of traditional technical routes.

[0020] 2. The advantages of the superelastic nickel-titanium alloy wire with both high elasticity and high plasticity prepared by the method of this invention are: 1) High hyperelastic stress: The high concentration of dissolved nickel atoms and the high density of nickel-rich local chemically ordered structure in the matrix significantly improve the yield strength of the austenite phase, making it possible to exhibit high hyperelastic stress. On the other hand, it lowers the martensitic transformation temperature and increases the critical stress required to induce martensitic transformation at room temperature to over 900 MPa, meeting the demand for high hyperelastic stress under high stress conditions.

[0021] 2) Large hyperelastic strain: The 1μm~4μm single B2 phase microcrystalline structure eliminates the hindering effect of the high-density second phase and ultrafine grain boundaries on the martensitic phase transformation, allowing the phase transformation strain to be fully output. At the same time, the locally chemically ordered structure increases the critical stress for dislocation slip, ensuring the output of high hyperelastic stress. Furthermore, it can itself undergo stress-induced martensitic phase transformation in synergy with the matrix, ensuring good recoverability. The combined effect of these two factors results in a large hyperelastic strain of ≥8%, ultimately achieving both high hyperelastic stress and large hyperelastic strain.

[0022] 3) High total elongation: After rapid crystallization by electrical pulse, cold-drawn wires achieve a micron-sized, pure microstructure without a second phase, eliminating the limitations on plasticity imposed by traditional ultrafine grains and hard second phases. Simultaneously, the locally chemically ordered structure deforms synergistically with the matrix during large deformation, which is beneficial for work hardening. The combined effect of these two factors results in a total fracture strain >60% for the hyperelastic nickel-titanium alloy wire, exhibiting both high elasticity and high plasticity, significantly superior to traditional hyperelastic nickel-titanium alloy wires.

[0023] 4) Precise and controllable microstructure: The present invention adopts a three-step strategy of "amorphization + rapid crystallization + low temperature aging" to achieve grain size control, phase composition control and local chemical order control step by step. This effectively avoids the drawbacks of multiple strengthening mechanisms interfering with each other and losing sight of one aspect in traditional processes, and provides a feasible technical path to obtain excellent comprehensive performance. Attached Figure Description

[0024] Figure 1 The image shown is a bright-field transmission electron microscope image of the cold-drawn and deformed wire in Example 1, with the inset being its diffraction photograph.

[0025] Figure 2 This is a bright-field transmission electron microscope image of the electrically pulsed crystallized filament in Example 1.

[0026] Figure 3 The image shows the XRD pattern of the electrically pulsed crystallized wire in Example 1.

[0027] Figure 4 This is a bright-field transmission electron microscope image of the aged NiTi alloy wire in Example 1.

[0028] Figure 5 The image shows the XRD pattern of the aged NiTi alloy wire from Example 1.

[0029] Figure 6 In the image, Figure a shows a HAADF-STEM image of the aged NiTi alloy wire from Example 1, and Figure b shows a 1 / 7 scale image of the aged NiTi alloy wire from Example 1. <123> IFFT image of the blob.

[0030] Figure 7 The image shows the superelastic tensile curve of the aged NiTi alloy wire in Example 1 at room temperature.

[0031] Figure 8 The image shows the hyperelastic tensile curve of the NiTi alloy wire in Comparative Example 1 at room temperature.

[0032] Figure 9 The image shows the hyperelastic tensile curve of the NiTi alloy wire in Comparative Example 2 at room temperature.

[0033] Figure 10 The image shows the hyperelastic tensile curve of the NiTi alloy wire in Comparative Example 3 at room temperature. Detailed Implementation

[0034] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described below with reference to specific embodiments and accompanying drawings. However, the embodiments described are not intended to limit the present invention. Unless otherwise specified, the experimental methods and detection methods described in the following embodiments are conventional methods; unless otherwise specified, the reagents and materials described are commercially available.

[0035] Example 1 This embodiment provides a method for preparing a superelastic nickel-rich NiTi alloy wire that combines high elasticity and high plasticity, including the following steps: S1. Weigh Ni and Ti as raw materials respectively, and repeatedly melt them in a vacuum induction melting furnace to obtain an ingot; homogenize the ingot in a vacuum environment at 1000℃ for 10 hours, and cool it in the furnace to obtain a treated ingot; hot forge the treated ingot at 850℃, and then heat the Ni after hot forging. 52 Ti 48 The alloy material is hot-drawn at 750℃ to obtain a raw material with a diameter of 0.7mm.

[0036] The chemical composition is Ni 52 Ti 48 The raw materials are subjected to high-temperature solution treatment at 750℃ for 20 minutes, and then water-cooled to obtain solution-treated filaments.

[0037] S2. The solution-treated filament is subjected to room temperature cold drawing deformation treatment with a deformation amount of 73% to obtain filament with a diameter of 0.36 mm.

[0038] Figure 1 The image is a bright-field transmission electron microscope image of the wire after cold drawing and deformation treatment. The inset is its diffraction photograph. Figure 1 This proves that after the wire is cold-drawn and deformed, its microstructure consists of an amorphous matrix and a very small number of nanocrystals.

[0039] S3. The wire is subjected to short-time electric pulse crystallization treatment, with a single pulse conduction time of 0.5ms, a pulse on / off ratio of 1:7, an AC voltage of 30V, a total conduction time of 50ms, and a heating temperature of 800℃, to obtain an electric pulse crystallized wire. Figure 2 This is a bright-field transmission electron microscope image of an electrically pulsed crystallized filament, from... Figure 2 It can be seen that the average grain size of the electropulse crystallized wire is 1μm~4μm. Figure 3 These are the XRD curves of the electrically pulsed crystallized wire. Figure 3 It can be seen that the electropulse crystallized filament is a single B2 phase.

[0040] S4. The electrically pulsed crystallized wire is subjected to low-temperature aging treatment at 250℃ for 24 hours, followed by water cooling treatment to obtain aged NiTi alloy wire, which is a superelastic nickel-rich NiTi alloy wire with both high elasticity and high plasticity.

[0041] Figure 4 This is a bright-field transmission electron microscope image of aged NiTi alloy wire after low-temperature aging treatment at 250℃ for 24 hours. Figure 4 It has been shown that the grain size of the electrically pulsed crystallized wire does not change after long-term aging at low temperature. Figure 5 The XRD curves are shown after low-temperature aging treatment at 250℃ for 24 hours. Figure 5 It can be seen that the aged NiTi alloy wire is still a single B2 phase. Figure 6 HAADF-STEM images after low-temperature aging at 250℃ for 24 hours and 1 / 7" <123> The IFFT images of the spots demonstrate that a uniformly distributed nanoscale nickel-rich locally chemically ordered structure with a diameter of 1 nm to 4 nm has formed inside the grains of the aged NiTi alloy wire. Figure 7 The image shows the hyperelastic tensile curve of the aged NiTi alloy wire provided in Example 1 at room temperature. This aged NiTi alloy wire achieved a high hyperelastic stress of 914 MPa, a hyperelastic strain of 8%, and an elongation of 63%.

[0042] Example 2 This embodiment provides a method for preparing a superelastic nickel-rich NiTi alloy wire that combines high elasticity and high plasticity, including the following steps: S1. Weigh Ni and Ti as raw materials respectively, and repeatedly melt them in a vacuum induction melting furnace to obtain an ingot; homogenize the ingot in a vacuum environment at 1000℃ for 10 hours, and cool it in the furnace to obtain a treated ingot; hot forge the treated ingot at 850℃, and then heat the Ni after hot forging. 52 Ti 48 The alloy material is hot-drawn at 750℃ to obtain the raw material.

[0043] The chemical composition is Ni 51.5 Ti 48.5 The raw materials are subjected to high-temperature solution treatment at 800℃ for 30 minutes, and then water-cooled to obtain solution-treated filaments.

[0044] S2. The solution-treated wire is subjected to room temperature cold drawing deformation treatment with a deformation amount of 65% to obtain the wire.

[0045] S3. The wire is subjected to short-time electric pulse crystallization treatment, with a single pulse conduction time of 0.5ms, a pulse on / off ratio of 1:7, an AC voltage of 10V, a total conduction time of 50ms, and a heating temperature of 750℃, to obtain an electric pulse crystallized wire. S4. The electrically pulsed crystallized wire is subjected to low-temperature aging treatment at 200℃ for 50h, followed by water cooling treatment to obtain aged NiTi alloy wire, which is a superelastic nickel-rich NiTi alloy wire with both high elasticity and high plasticity.

[0046] Example 3 This embodiment provides a method for preparing a superelastic nickel-rich NiTi alloy wire that combines high elasticity and high plasticity, including the following steps: S1. Weigh Ni and Ti as raw materials respectively, and repeatedly melt them in a vacuum induction melting furnace to obtain an ingot; homogenize the ingot in a vacuum environment at 1000℃ for 10 hours, and cool it in the furnace to obtain a treated ingot; hot forge the treated ingot at 850℃, and then heat the Ni after hot forging. 52 Ti 48 The alloy material is hot-drawn at 750℃ to obtain the raw material.

[0047] The chemical composition is Ni 52.5 Ti 47.5 The raw materials are subjected to high-temperature solution treatment at 780℃ for 40 minutes, and then water-cooled to obtain solution-treated filaments.

[0048] S2. The solution-treated wire is subjected to room temperature cold drawing deformation treatment with a deformation amount of 65% to obtain the wire.

[0049] S3. The wire is subjected to short-time electric pulse crystallization treatment, with a single pulse conduction time of 0.2ms, a pulse on / off ratio of 1:7, an AC voltage of 50V, a total conduction time of 50ms, and a heating temperature of 850℃, to obtain an electric pulse crystallized wire. S4. The electrically pulsed crystallized wire is subjected to low-temperature aging treatment at 230℃ for 10 hours, followed by water cooling treatment to obtain aged NiTi alloy wire, which is a superelastic nickel-rich NiTi alloy wire with both high elastic stress and high plasticity.

[0050] Comparative Example 1 The same nickel-rich nickel-titanium wire with the same diameter and composition as in Example 1 was selected, and the same solution annealing process, cold deformation process, and electric pulse crystallization process as in Example 1 were adopted.

[0051] The difference from Example 1 is that this comparative example does not undergo low-temperature aging treatment after electropulse crystallization, but directly performs room temperature tensile testing on the electropulse crystallized filament.

[0052] Figure 8 The superelastic tensile curve of the NiTi alloy wire provided for Comparative Example 1 at room temperature shows that the comparative example did not exhibit superelastic properties and fractured at 6%.

[0053] This comparative example illustrates that the low-temperature aging process plays a crucial role in generating superelastic properties.

[0054] Comparative Example 2 The same nickel-rich nickel-titanium wire with the same diameter and composition as in Example 1 was selected, and the same solution annealing process, cold deformation process, and electric pulse crystallization process as in Example 1 were adopted.

[0055] The difference from Example 1 is that the aging treatment conditions in this comparative example are different. The electrically pulsed crystallized filament is aged at 450°C for 2 hours, followed by water cooling.

[0056] Figure 9 The superelastic tensile curve of the NiTi alloy wire provided in Comparative Example 2 at room temperature shows that its superelastic stress is reduced to 580 MPa, which is significantly lower than 914 MPa in Example 1; it can only recover 6.6% when stretched by 8%, and the superelastic recovery rate is significantly reduced; the total fracture strain is drastically reduced to 22%.

[0057] This comparative example illustrates that if the low-temperature aging treatment is replaced with conventional medium-temperature aging treatment, the aforementioned excellent comprehensive mechanical properties cannot be obtained.

[0058] Comparative Example 3 Nickel-rich nickel-titanium wire with the same diameter and composition as in Example 1 was selected, and the same solution annealing process, cold deformation process and low-temperature aging process as in Example 1 were adopted.

[0059] The difference from Example 1 is that the comparative example replaces the electric pulse crystallization treatment with the traditional muffle furnace medium-temperature annealing treatment, that is, holding at 600°C for 5 minutes in a muffle furnace and then water cooling to obtain a wire with a grain size comparable to that of Example 1.

[0060] Figure 10 The superelastic tensile curve of the NiTi alloy wire provided in Comparative Example 3 at room temperature shows that the plateau stress of the wire is only 500 MPa, which is 400 MPa lower than that in Example 1, and the total elongation is only 38%.

[0061] This comparative example illustrates that if the electro-pulse crystallization treatment is replaced with traditional muffle furnace medium-temperature annealing, the aforementioned excellent comprehensive mechanical properties cannot be obtained.

[0062] As can be seen from Comparative Examples 1 to 3, the low-temperature aging process adopted in this invention introduces a nickel-rich local chemically ordered structure instead of precipitating the Ni4Ti3 phase, and is combined with "intense cold deformation + electric pulse crystallization", which is the key to achieving a synergistic improvement of "high hyperelastic stress (>900MPa), large hyperelastic strain (about 8%) and high total elongation (>60%)".

[0063] Obviously, the above embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A method for preparing a superelastic nickel-titanium alloy wire possessing both high elasticity and high plasticity, characterized in that, Includes the following steps: Using hot-drawn nickel-titanium alloy wire as raw material, the chemical composition of the nickel-titanium alloy wire is Ni a Ti 100-a Where 51.5≤a≤52.5, and a is the atomic percentage; First, the raw material is subjected to high-temperature solution annealing, and then cold drawing deformation with a deformation amount of ≥65% is carried out at room temperature to achieve alloy amorphization and obtain wire material; Short-time electric pulse crystallization treatment was applied to the wire to obtain electric pulse crystallized wire, which caused the amorphous structure to crystallize rapidly and suppressed the diffusion of Ni atoms, forming a single austenitic B2 phase with a grain size of 1μm~4μm. By subjecting electrically pulsed crystallized wires to low-temperature aging treatment, a locally chemically ordered structure rich in nickel is formed without changing the grain size of the treated wires, resulting in a superelastic nickel-titanium alloy wire that combines high elasticity and high plasticity.

2. The method for preparing the hyperelastic nickel-titanium alloy wire with both high elasticity and high plasticity according to claim 1, characterized in that, The diameter of the raw material is 0.2mm~2mm.

3. The method for preparing the hyperelastic nickel-titanium alloy wire with both high elasticity and high plasticity according to claim 1, characterized in that, The conditions for high-temperature solution annealing are: holding at 750℃~800℃ for 20min~40min.

4. The method for preparing the hyperelastic nickel-titanium alloy wire with both high elasticity and high plasticity according to claim 1, characterized in that, The diameter of the wire is 0.1mm~1.0mm.

5. The method for preparing the hyperelastic nickel-titanium alloy wire with both high elasticity and high plasticity according to claim 1, characterized in that, The electrical pulse parameters for short-time electrical pulse crystallization treatment are: AC voltage 10V~50V, single pulse conduction time 0.2ms~0.5ms, pulse on / off ratio 1:7, total conduction time ≤0.5s, and heating temperature 750℃~850℃.

6. The method for preparing the hyperelastic nickel-titanium alloy wire with both high elasticity and high plasticity according to claim 1, characterized in that, The conditions for low-temperature aging treatment are: treatment at 200℃~250℃ for 10h~50h.

7. A superelastic nickel-titanium alloy wire possessing both high elasticity and high plasticity, characterized in that, It was prepared by the preparation method described in claims 1 to 6.

8. The superelastic nickel-titanium alloy wire with both high elasticity and high plasticity according to claim 7, characterized in that, The microstructure of the superelastic nickel-titanium alloy wire, which combines high elasticity and high plasticity, consists of single B2 phase austenite grains with a size of 1μm to 4μm, and nickel-rich locally chemically ordered structures with a size of 1nm to 4nm are dispersed inside the B2 phase austenite grains.

9. The superelastic nickel-titanium alloy wire with both high elasticity and high plasticity according to claim 7, characterized in that, The superelastic nickel-titanium alloy wire, which combines high superelastic stress and high plasticity, has a superelastic stress >900MPa, a superelastic strain ≥8%, and a total elongation >60%.

10. The application of the superelastic nickel-titanium alloy wire with high elasticity and high plasticity as described in claim 7 in the preparation of guide wires, vascular stents, flexible connectors and driving elements.

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