47 results about "Niti alloy" patented technology

The invention relates to the technical field of medical implants, in particular to a 4D printing-based porous Niti alloy bionic bone gradient structure construction method, which comprises the steps of patient bone data acquisition, bionic gradient model design, NiTi powder preparation, 4D printing, thermal treatment activation of memory effect, surface functionalization treatment and mechanical / biological performance test. The method is characterized by comprising the following preparation steps: accurately acquiring bone structure data through CT / MRI, combining Mimics pretreatment and UG / NX modeling, designing aperture and porosity for differentiation of cortical bone (low porosity of 30%-40%) and cancellous bone (high porosity of 50%-70%), simulating typical load working conditions through ANSYS, enabling the elastic modulus (3-15 GPa) and compressive strength (80-200 MPa) to be close to natural bone, and finally obtaining the bone structure data through the CT / MRI, the pore diameter and porosity of the cortical bone (low porosity of 30%-40%) and the porosity of the cancellous bone (high porosity of 50%-70%). According to the design, the elastic modulus difference between the implant and the host bone is remarkably reduced, the bone resorption problem caused by stress shielding is avoided, meanwhile, continuous porosity transition is achieved through the power gradual change technology, and the structural stability under the complex load is improved.

The invention discloses a method for coating a Ca-Cur submicron modified material-doped PLA layer on the surface of an Ag-DCPD film layer, and relates to the technical field of biological coatings on the surfaces of medical materials. The method comprises the following steps: manufacturing an LPBF-NiTi alloy matrix by adopting a laser powder bed melting additive manufacturing technology, and carrying out pretreatment on the LPBF-NiTi alloy matrix; the pretreated LPBF-NiTi alloy matrix is subjected to electrochemical deposition in an electrolyte solution, and the LPBF-NiTi alloy matrix with the deposited Ag-DCPD film layer is obtained; the preparation method comprises the following steps: dissolving CaCl2 and curcumin in absolute ethyl alcohol, putting the solution into a closed container filled with (NH4) 2CO3, and carrying out constant-temperature reaction to obtain a Ca-Cur submicron modified material; polylactic acid is dissolved in dichloromethane, then the Ca-Cur submicron modified material is dispersed in the dichloromethane, and a leaching solution is obtained; and the LPBF-NiTi alloy matrix on which the Ag-DCPD film layer is deposited is subjected to repeated dipping and pulling in the leaching solution, and the LPBF-NiTi alloy matrix coated with the Ag-DCPD / PLA / Ca-Cur composite film layer is obtained. According to the invention, the corrosion resistance, the biocompatibility and the antibacterial and anti-inflammatory performance of the Ag-DCPD film layer are successfully improved.

The invention relates to the technical field of brazing, in particular to a low-temperature preparation method of a nickel-titanium alloy / zirconia ceramic corrosion-resistant joint. In order to solve the problems that an implantable medical device prepared through an existing NiTi shape memory alloy and zirconia ceramic connecting method is poor in biocompatibility and not suitable for long-term service in a human body, the invention provides the NiTi shape memory alloy and zirconia ceramic low-temperature indirect brazing method which is good in biocompatibility and excellent in corrosion resistance. The brazing method comprises the following steps: (1) preparing metallized brazing filler metal; (2) metalizing the zirconia ceramic; (3) brazing the NiTi alloy and the zirconia ceramic; after the obtained joint is subjected to an electrochemical test in SBF simulated body fluid, the corrosion resistance is good; the highest strength of a brazed joint is 31 MPa, and the use strength of an implantable medical device can be met.

The invention belongs to the technical field of electric arc additive manufacturing, and particularly relates to an electric arc additive preparation method of NiTi alloy. The invention provides an electric arc additive preparation method of NiTi alloy, which comprises the following steps of: preparing a NiTi layer on the surface of a NiTi substrate by adopting an electric arc additive process by taking a NiTi alloy wire as a raw material, hammering the NiTi layer, and repeating the operation until a printed piece is obtained. The tensile strength of the obtained alloy is not lower than 715 MPa, the ductility is not lower than 8.2%, and good matching of high strength and excellent ductility is achieved; the preparation method is simple, short in time consumption, safe and environment-friendly, and meets industrial application requirements.

The invention discloses a preparation method of a novel high-performance Ti-Zr-Mo-Sn super-elastic beta titanium alloy. The invention provides a brand-new super-elastic beta titanium alloy system, namely Ti-Zr-Mo-Sn, and preparation of the novel titanium alloy can be achieved by combining the processes of electric arc melting, cold rolling, recrystallization treatment and the like. The preparation method comprises the following specific steps: 1) weighing pure metals such as titanium, zirconium, molybdenum and tin, and preparing a button cast ingot; 2) preparing a standard tensile sample; 3) recrystallization annealing treatment; and 4) mechanical property detection. The problems that NiTi alloy causes allergy and Ti-Nb-based super-elastic beta titanium alloy is poor in mechanical property are solved, and further development of the high-performance biomedical super-elastic beta titanium alloy is promoted.

The application discloses a brazing filler metal for titanium alloy and stainless steel connection and application thereof, and the brazing filler metal comprises an Ag-Cu eutectic brazing filler metal base and NiTi alloy particles. By introducing the NiTi alloy particles into the Ag-Cu eutectic brazing filler metal base, the Ni and Ti in the interface neighborhood are cooperatively involved in diffusion and reaction, the wetting and forming consistency of the brazing filler metal are cooperatively improved, the interface reaction layer is formed into a discrete thin layer, the continuous brittle reaction layer is inhibited from being generated, the risk of crack propagation along the interface is reduced, the shear strength of the brazing filler metal welding joint for titanium alloy and stainless steel connection is remarkably improved, and the forming quality and batch consistency of the brazing joint are improved.

The invention relates to the technical field of medium-entropy alloy, in particular to a medium-entropy alloy composite material and a preparation method and application thereof. The invention provides a medium-entropy alloy composite material, which is prepared from the following raw materials in parts by mass: 70 to 95 parts of CoCrNi medium-entropy alloy and 5 to 30 parts of NiTi alloy, and the crystalline phase of the NiTi alloy comprises a B2 phase. The medium-entropy alloy composite material has high strength, high hardness and high wear resistance at the same time.

This invention relates to a device and process for preparing self-reinforcing and self-healing shape memory composite materials. It innovatively employs a vacuum-assisted injection method to composite and cure epoxy-based shape memory polymers (SMP) with tensioned NiTi shape memory alloy (SMA) wires. The thermotropic shrinkage properties of the NiTi alloy wires are utilized to improve the stiffness of the epoxy matrix while simultaneously healing internal microcracks. This preparation process and supporting equipment can minimize defects in the preparation and use of composite materials and enable semi-automatic control of the composite material's stiffness.

The application discloses a kind of based on NiTi alloy's chip liquid cooling plate flow channel topological optimization design method, comprising: obtaining chip heat source distribution, determine two-dimensional design domain and establish flow-thermal coupling numerical model;Determine material, environment and boundary parameter;Based on solid isotropic material interpolation format, express physical property parameter as the function of design variable, construct topological optimization mathematical model;With minimum fluid viscosity energy dissipation rate and design domain average temperature as joint target, with fluid volume fraction and temperature interval as constraint, carry out iterative solution, obtain two-dimensional optimal flow channel topological configuration.Wherein, NiTi shape memory alloy unit is arranged on the wall surface of flow channel, adaptive flow regulation based on temperature sensing can be realized.The application realizes the collaborative optimization of heat dissipation performance and flow resistance, can effectively suppress hot spot, and design efficiency is high.

The present invention discloses a mold and method for preparing a biomimetic bone radial gradient porous NiTi alloy, comprising the following steps: 1) mold design and assembly; 2) slurry preparation; 3) co-injection molding; 4) curing and drying; 5) degreasing and sintering; and 6) pore-forming agent removal. The biomimetic bone radial gradient porous nickel-titanium alloy prepared by the present invention has a relatively continuous porosity variation from 15% in the outer layer to a maximum of 70% in the inner layer, and an average pore size variation from 30 μm in the outer layer to over 400 μm in the inner layer. The mechanical properties are substantially matched to those of bone. The biomimetic bone radial gradient nickel-titanium alloy prepared by the method of the present invention can be used as an ideal artificial bone tissue repair or replacement material, and is suitable for directly preparing materials such as dental implants, artificial joints, and bone trauma products without the need for subsequent processing.

A self-adaptive temperature compensation type large-span arch bridge main arch truss section connecting device belongs to the field of bridge engineering structures, and comprises two groups of SMA (Shape Memory Alloy) elastic gaskets which are clamped between two adjacent main arch truss section flange plates, are symmetrically arranged up and down and are made of shape memory alloys; the prestress tension screws penetrate through the flange plates on the two sides and the SMA elastic gaskets, and high-strength nuts are arranged at the two ends of each prestress tension screw in a matched mode; the two ends of the hydraulic damper are detachably connected with the flange plates of the adjacent sections through spherical hinges respectively; the SMA elastic gasket is a wave-shaped NiTi alloy thin plate; the hydraulic damper has the beneficial effects that the SMA elastic gasket can dynamically absorb and compensate axial displacement caused by thermal expansion and cold contraction, the hydraulic damper can dynamically absorb and compensate radial displacement caused by vibration, accurate initial pre-tightening force can be applied to the SMA gasket by properly tightening the high-strength nut, and the fault-tolerant capability is improved.

The present invention relates to the technical field of arc additive manufacturing, and particularly to a method for additive manufacturing of heterogeneous dual-wire arc of NiTi-based shape memory alloy. The manufacturing method is to feed NiTi alloy wire and metal wire simultaneously through a dual-wire arc additive device, and use an ultra-high frequency pulsed TIG welding power source to realize the additive manufacturing of heterogeneous dual-wire arc of NiTi-based shape memory alloy. The present invention is used to solve problems such as low phase transformation temperature and large phase transformation hysteresis in existing arc additive manufacturing technology. Moreover, the ultra-high frequency pulsed TIG arc can improve the microstructure morphology, thereby being beneficial to stabilizing and improving the performance of NiTi-based alloys, broadening the application fields of NiTi-based ternary alloys, and providing an effective solution for arc additive manufacturing of NiTi-based shape memory alloys.

The utility model discloses a stable type niti alloy vertebral plate structure which comprises a vertebral plate body, connecting plates are fixedly installed on the two sides of the vertebral plate body respectively, an adjusting installation assembly is arranged on one side of each connecting plate, each adjusting installation assembly comprises a clamping groove and a first screw hole, the clamping grooves are formed in one sides of the connecting plates, the first screw holes are formed in one sides of the connecting plates, and the first screw holes are connected with the clamping grooves. A clamping groove is formed in the middle of the vertebral plate, a clamping block is connected to one side of the clamping groove in a clamped mode, a second screw hole is formed in one side of the clamping block, a fixing plate is fixedly installed on one side of the clamping block, a third screw hole is formed in one side of the fixing plate, and a first bolt is connected to the inner side wall of the third screw hole through threads. According to the stable niti alloy vertebral plate structure, adjustment can be carried out according to the condition of the lumbar vertebra of a patient through the arranged adjusting and mounting assembly, the fixing plate of the lumbar vertebra which is not suitable for bolting can be detached so as to prevent the bolt from causing secondary damage to the lumbar vertebra, and the stable niti alloy vertebral plate structure is helpful to the lumbar vertebra of the patient, so that the use effect is better.

The invention belongs to the technical field of preparation of cladding coatings on material surfaces, and particularly relates to a titanium alloy bearing material and a preparation method thereof. The titanium alloy bearing material comprises a titanium alloy substrate and a NiTi alloy coating cladding the titanium alloy substrate, and the NiTi alloy coating is composed of, by mass, 33-40% of Ti and the balance Ni; niTi structures at the joint of the NiTi alloy coating and the titanium alloy substrate are planar crystals and cellular crystals, and the NiTi structures above the joint are columnar crystals and columnar dendritic crystals. The NiTi structure with specific characteristics is formed on the surface of the titanium alloy substrate, the highest hardness reaches 677.41 HV0.2 and is 2.05 times that of the titanium alloy substrate, and the wear resistance is improved by 53% compared with that of the titanium alloy substrate. On the whole, the cladding coating effectively improves the wear resistance and the bearing capacity of the titanium alloy surface.

The application discloses a method for coating a PLA layer of Ag-DCPD film layer surface with doped Ca-Cur submicron modified material, and relates to the technical field of medical material surface biological coating. The method comprises the following steps: an LPBF-NiTi alloy base is manufactured by using a laser powder bed fusion additive manufacturing technology and is pretreated; the pretreated LPBF-NiTi alloy base is subjected to electrochemical deposition in an electrolyte solution to obtain an LPBF-NiTi alloy base with a deposited Ag-DCPD film layer; CaCl2 and curcumin are dissolved in anhydrous ethanol, and are placed in a sealed container containing (NH4)2CO3 for constant-temperature reaction to obtain Ca-Cur submicron modified material; polylactic acid is dissolved in dichloromethane, and then the Ca-Cur submicron modified material is dispersed in the polylactic acid to obtain a leaching solution; the LPBF-NiTi alloy base with the deposited Ag-DCPD film layer is repeatedly immersed and pulled in the leaching solution to obtain an LPBF-NiTi alloy base coated with an Ag-DCPD / PLA / Ca-Cur composite film layer. Through the method, the corrosion resistance, biocompatibility and antibacterial and anti-inflammatory performance of the Ag-DCPD film layer are successfully improved.

The present invention discloses a method for regulating the mechanical properties of an additive manufactured nickel-titanium alloy component, belonging to the technical field of laser additive manufacturing, and comprising the following steps: Step 1: Prepare a nickel-titanium alloy component through a powder bed powder feeding laser additive manufacturing process; Step 2: Perform heat treatment on the nickel-titanium alloy component. The heat treatment temperature is between 300°C and 550°C, and the heat treatment time is between 0.1 h and 3 h. During the heat treatment, an external load is applied to the nickel-titanium alloy component. The direction of the applied external load is parallel to the forming direction of the nickel-titanium alloy component, and the stress magnitude applied to the nickel-titanium alloy component should be in the range of 0.2 - 10 N / mm<supgt;2< / supgt; to achieve the regulation of the mechanical properties of the nickel-titanium alloy component. This method can effectively regulate the mechanical properties of the nickel-titanium alloy component and further promote the application of the nickel-titanium alloy component in the field of buffer energy absorption.

The invention relates to the technical field of additive manufacturing, in particular to a method for regulating and controlling components of an additive manufacturing NiTi shape memory alloy to enable the components to approach target components. Aiming at the problem that components of the additive manufacturing NiTi shape alloy are unstable, the invention creatively puts forward to establish the relationship between the process parameter and the Ni atom increment, and correspondingly regulates and controls the components of the additive manufacturing NiTi shape alloy by increasing the content of Ni atoms in the second NiTi alloy powder by determining the evaporation capacity of the Ni atoms under the process parameter, so that the additive manufacturing NiTi shape alloy is more stable, and the performance of the additive manufacturing NiTi shape alloy is improved. And the components of the NiTi shape alloy prepared after regulation and control are close to target components.

The utility model discloses a porous structure niti alloy vertebral plate which comprises a vertebral plate body, a limiting groove is formed in the vertebral plate body, a sliding block is connected in the vertebral plate body in a sliding mode, the two sides of the sliding block are connected with the interior of the limiting groove in a sliding mode, a secondary positioning hole is formed in the sliding block, and the secondary positioning hole is connected with the interior of the limiting groove in a sliding mode. End V-shaped recesses are formed in the two ends of the vertebral plate main body, side V-shaped recesses are formed in the two sides of the vertebral plate main body, and a through groove is formed in the vertebral plate main body. According to the niti alloy vertebral plate with the porous structure, the vertebral plate main body is preliminarily fixed through cooperation of second auxiliary positioning holes and screws, then reinforced fixing can be conducted again through cooperation of main positioning holes and screws, and sliding adjustment can be conducted along limiting grooves by sliding sliding blocks; after the sliding block moves to a proper position, key parts can be reinforced through the secondary positioning holes and the screws.

The present invention relates to a strap shoe, such as an ankle strap, a gladiator strap or a foot strap, having an improved fit, comprising an upper (12), a bottom portion (11) to which the upper (12) is fastened, and a strap (14) connected to the bottom portion (11) and / or to the upper (12) and / or incorporated into at least one thereof (11, 12), for fastening the footwear to the foot and / or ankle of a user, and characterised in that the strap (14) comprises at least one strap portion made of a NiTi alloy comprising at least two zones (14a,14b) with different mechanical properties, in particular bending response mechanical properties. The present invention further relates to a process for making a strap shoe.

This invention discloses a method for preparing a DCPD / PEI / SiO2-CuS photothermal multifunctional film layer on the surface of an additively manufactured NiTi alloy, and the additively manufactured NiTi alloy prepared by this method, relating to the field of surface modification technology for medical materials. The method includes: depositing a DCPD film layer on the surface of an alloy substrate; ultrasonically mixing mesoporous SiO2 material in a mixed solution of anhydrous ethanol and deionized water, adding CuS powder for dispersion, centrifuging, washing, drying, and heat treatment to obtain a SiO2-CuS modified material; dissolving PEI in dimethylacetamide, uniformly dispersing the SiO2-CuS modified material therein to obtain an extraction solution; then immersing and pulling the NiTi alloy with the deposited DCPD film layer in the extraction solution to complete the coating of the photothermal multifunctional film layer on the NiTi alloy surface. This invention successfully improves the corrosion resistance and biocompatibility of the NiTi alloy substrate and endows its surface with highly efficient photothermal antibacterial properties.

This invention belongs to the field of composite material design and discloses a partition-wall NiTi composite material superstructure and its manufacturing method. The superstructure comprises a NiTi alloy superstructure support and a resin material filled within the support. The resin material is one or a composite of several of polyurethane resin, epoxy resin, polycarbonate, ethylene-vinyl acetate, and thermoplastic polyester elastomer. The NiTi alloy superstructure support consists of multiple vertically stacked chambers. Each chamber is composed of upper and lower partitions and an intermediate wall. Adjacent chambers share a partition, which is a solid thin-sheet structure. This invention proposes a new approach for directly synthesizing partition-wall NiTi composite material superstructures that possess high lightweight, excellent mechanical properties, high precision, and energy absorption performance, providing a technical foundation for the engineering application of multi-scale porous structures with impact resistance and energy absorption protection characteristics.

This invention discloses a high-martensite-content, pitting-resistant NiTi alloy and its laser powder bed melting preparation method and application, belonging to the technical fields of nickel-titanium shape memory alloys, additive manufacturing, and material corrosion protection. The method involves: under inert gas protection, LPBF forming is performed using a laser with a power of 180–220 W, a scanning speed of 1085–1325 mm / s, and a scanning spacing of 80–100 μm to form an austenitic structure with orientation characteristics; subsequently, a medium-temperature annealing treatment is performed at 500–550 °C for 180–240 min to induce the austenite to transform into martensite and inherit the orientation characteristics, achieving a martensite content of 42–55%, while simultaneously promoting the uniform distribution of nano-precipitates. The prepared alloy can effectively reduce electrochemical inhomogeneity, significantly improve pitting corrosion resistance in chlorine-containing environments, and has an overpassivation potential of 1300–1600 mV, exhibiting both good functional properties and promising engineering applications.

The invention relates to the technical field of concrete, in particular to self-repairing ultra-high-performance conductive concrete and a preparation method thereof.The self-repairing ultra-high-performance conductive concrete is prepared from, by weight, 1000 parts of cementing material, 800 parts of 525 Portland cement and 200 parts of silica fume; the filler is prepared from 100 parts of quartz powder with the particle size of 200 to 300 meshes and 800 parts of quartz sand with the particle size of 40 to 70 meshes. According to the invention, three functions of ultrahigh performance (compressive strength is greater than 120MPa), self-repairing (SMA driving) and electric conduction (double-fiber network) are successfully integrated into one material; the shape memory effect of NiTi alloy fibers is utilized, small cracks can be actively closed, the repairing efficiency is good, and the performance can be repeatedly triggered.

The present invention belongs to the field of additive manufacturing technology, and discloses a 4D printing method capable of in-situ regulating functional properties of nickel-titanium (NiTi) alloys and the application thereof. The method comprises the following steps: subjecting NiTi alloy bars to atomization milling to obtain NiTi alloy powder with a particle size of 15-53 μm, placing the NiTi alloy powder in a discharge plasma assisted ball mill for discharge treatment to promote the activation of powder activity, then adding nano-sized Ni powder with a particle size of 100-800 nm to obtain mixed powder, then continuing the discharge treatment to realize the metallurgical bonding between the NiTi alloy powder and the nano-sized Ni powder to obtain the modified powder, and finally using the additive manufacturing technology to prepare and form the modified powder into a functionalized NiTi alloy. The present invention achieves the metallurgical bonding between the nano-sized Ni powder and the large-sized spherical NiTi alloy powder by adding the nano-sized Ni powder in the process of discharge treatment, which is conducive to preparing a bulk alloy with uniform composition, structure and properties and the parts made therewith.

The invention relates to a NiTi alloy wire high-diameter uniformity electrochemical machining thinning method which comprises the following steps: S1, removing a surface oxide layer of a NiTi alloy wire; s2, the NiTi alloy wire treated in the step S1 is heated to the austenite transformation temperature or above; s3, the NiTi alloy wire treated in the S2 is fixed in an electrolytic tank, the NiTi alloy wire is kept parallel to a tool cathode, power parameters are set, first electrochemical machining treatment is carried out, and the NiTi alloy wire is thinned in the axial direction in a gradient mode to form an inverted cone shape; s4, the NiTi alloy wire treated in the S3 is taken out and placed in the electrolytic tank in an inverted mode, secondary electrochemical machining treatment is carried out with the same parameters, the NiTi alloy wire is thinned in the axial direction in a gradient mode, the thinning amount of the primary electrochemical machining treatment is equal to the thinning amount of the secondary electrochemical machining treatment, and therefore the inverted cone shape is changed into the cylindrical shape; and S5, the S3 and the S4 are repeated till the NiTi alloy wire is thinned to the required diameter. According to the method, NiTi alloy wires with different diameters and the same phase change behavior and mechanical property can be prepared.

The invention relates to the technical field of biomedical materials, in particular to a preparation method of a hyperelastic low-modulus antibacterial bone implant, which comprises the following steps: firstly, designing a porous structure model with specific pore parameters based on a three-period minimal curved surface (Gyandroid), then uniformly mixing NiTi alloy powder with a small amount of Ag powder, and preparing a porous structure model; and finally, carrying out integrated forming by adopting optimized laser powder bed melting process parameters under a protective atmosphere. The prepared bone implant has the low elastic modulus of 1.5-3.5 GPa, can be well matched with human bones, and remarkably reduces the stress shielding effect; and meanwhile, the superelasticity of the NiTi alloy is reserved, and the alloy has the capability of recoverable deformation under the strain of 4%. Besides, by adding the Ag element, the antibacterial rates of the implant to staphylococcus aureus and escherichia coli exceed 90%, the material is endowed with excellent antibacterial performance on the premise of not excessively changing the matrix tissue, and the clinical safety and service reliability of the implant are effectively improved.

The present disclosure provides a method for regulating dynamic recrystallization of NiTi alloy by Ti2Ni phase, comprising: after open-die forging of the as-cast NiTi alloy, performing staged thermal mechanical treatment, first performing first-stage thermal deformation, then performing second-stage thermal deformation, and rapidly water cooling after deformation; by regulating the two-stage variable-temperature and variable-strain rate, Ti2Ni, which is originally considered as a harmful phase, is converted into a micro tool for controlling grain boundary migration; by using Ti2Ni to induce particle-induced nucleation in the low-temperature region, the critical strain required for complete recrystallization is reduced, and the limitation of traditional single thermal coupling driving is broken; this innovative mechanism not only promotes the occurrence of austenite grain dynamic recrystallization process by increasing nucleation sites, but also inhibits the organization coarsening caused by high-temperature grain boundary migration by using the pinning effect of the second phase particles, so as to realize the precise regulation of the uniformity of the organization under a lower deformation amount.

The invention discloses a bionic bone implant for a 4D printed porous NiTi alloy spine, and relates to the technical field of bionic bone implants.The bionic bone implant comprises an implant body, and the implant body is integrally formed by porous NiTi alloy containing microelements through the 4D printing technology; after the implant main body is implanted into a human body, the shape or porosity of the implant main body can be controllably changed under the stimulation of the body temperature of 35-42 DEG C, the shape recovery rate is larger than or equal to 90%, and the porosity adjusting range is + / -5%-10%. According to the bionic bone implant for the 4D printed porous NiTi alloy spine, the porosity and the aperture are regulated and controlled, and a gradient porous structure is designed in the mechanical conduction direction of the spine, so that the elastic modulus is reduced, the elastic modulus is highly matched with the mechanical property of cancellous bones of the spine of a human body, the stress shielding effect is effectively eliminated, and the risk of surrounding bone atrophy is reduced; meanwhile, the shape memory effect of the NiTi alloy can realize controllable adjustment of shape / porosity under the stimulation of body temperature, the shape memory effect is adaptive to the physiological curvature change of the post-operation spine, and the long-term stability of the implant is improved.

The application provides a method for obtaining superelasticity of a shape memory alloy, and belongs to the technical field of shape memory alloys. The method comprises the following steps: determining the equilibrium temperature T0 of a parent phase and a martensite phase and the end temperature A of a reverse martensite phase transformation of the martensite phase based on a thermal induced phase transformation curve of the shape memory alloy f ; applying stress to the shape memory alloy at the equilibrium temperature to induce the martensite phase transformation but not exceeding the tensile strength of the shape memory alloy, and then unloading. The application utilizes the feature that the critical stress required for stress-induced martensite phase transformation of a NiTi alloy at the equilibrium temperature (T0) of the parent phase and the martensite phase is small, and applies sufficient stress to the alloy at T0, so that stress-induced martensite phase transformation occurs first, and then unloading, and corresponding dislocations are introduced after the phase transformation of the matrix. Since the alloy has memorized the stress-induced martensite phase transformation path through the dislocations, at the same temperature, the stress-induced martensite that is originally inhibited reappears the phase transformation and exhibits superelasticity.

The application provides an isotropic NiTi alloy, a preparation method and application thereof. The preparation method of the NiTi alloy further comprises heat treatment on a blank, and the heat treatment comprises the following steps in sequence: solid solution treatment is performed on the blank at 670 DEG C to 720 DEG C for 5 min to 10 min, then first cooling is performed at a first cooling rate to obtain a solid solution product; the solid solution product is heated in a silicon oil medium at a heating rate of 3 DEG C / min to 5 DEG C / min, and aging treatment is performed at 100 DEG C to 300 DEG C for 12 h to 72 h, then second cooling is performed at a second cooling rate to obtain the isotropic NiTi alloy. Based on the two-stage heat treatment process of short-time low-temperature solid solution and silicon oil uniform-temperature aging, the homogenization of tensile properties of samples in different printing directions is realized, and the NiTi alloy component with high performance consistency is obtained.