Abstract: Nitinol shape memory alloy is a new type of functional material, which has become the focus of research in the field of functional materials. This paper analyzes the characteristics and functions of Ni-Ti alloy shape memory alloys, and aims to provide some inspiration for the future development of Ni-Ti alloy shape memory alloys.

Keywords: Ni-Ti alloy shape memory alloy features effect

Ni-Ti alloy shape memory material is a special material combining sensing and driving, and Ni-Ti alloy shape memory alloy is a very critical part of Ni-Ti alloy shape memory material. Nickel-titanium shape memory alloy refers to a type of alloy whose shape is changed to another shape after low-temperature plastic deformation in a certain initial state, and then heated by means such as heating.

I. Characteristics of Ni-Ti alloy shape memory alloy

(I) Shape Memory

Ni-Ti alloy shape memory alloy will automatically recover its shape after a certain heat treatment. This change is the shape memory characteristic of Ni-Ti alloy shape memory alloy. Shape memory can be divided into one-way shape memory, two-way shape memory, and full shape memory according to the recovered condition.

(II) Super Elasticity

Ni-Ti alloy shape memory alloy will be deformed when subjected to external force, and will return to its original state after removing the external force. This is the super-elastic characteristic of Ni-Ti alloy shape memory alloy. After the superelastic deformation of the Ni-Ti alloy shape memory alloy, it will directly cause the martensite transformation, and removing the external force will cause the martensite reverse transformation.

(3) Damping

Nitinol shape memory alloy is because of the self-adjustment of phase transition and the interface and motion generated during the phase transition, which has very good damping.

(4) Resistive

The martensitic nickel-titanium shape memory alloy has a linear relationship between resistance and strain during deformation. When a phase change occurs, the slope of the curve will decrease, but the linear relationship will be maintained before and after the martensite phase.

The role of Ni-Ti alloy shape memory alloy

Because of its unique nickel-titanium shape memory alloy function, nickel-titanium shape memory alloys also have advantages such as superelasticity, wear resistance and corrosion resistance, so they are widely used in many fields.

(1) Mechanical Engineering

Nitinol shape memory alloys were originally used in pipe joints and fasteners in the machinery industry. Specifically, at the connection of mechanical parts, pipelines, etc., at the interface of the aircraft for aerial refueling, nickel-titanium alloy shape memory alloy is used to form a casing with an outer diameter 3% larger than the inner diameter, and the casing is expanded at a certain temperature. The diameter is about 8%. During assembly, the sleeve is taken out of liquid nitrogen and the tube is inserted from both ends. If the temperature rises to normal temperature, the temperature can be changed by electric heating. The Ni-Ti alloy shape memory alloy at the air refueling interface is deformed. Ni-Ti alloy The sleeve made of shape memory alloy shrinks to form a tight seal, thereby achieving tight oil leakage, and the effect is much higher than traditional welding. Therefore, nickel-titanium alloy shape memory alloys are especially suitable for aerospace, shipbuilding, oil pipelines and other fields. In places where construction is inconvenient, nickel-titanium alloy shape memory alloys can be used to make pins and put them into holes for heating. Therefore, the temperature-sensing properties of nickel-titanium shape memory alloys are used to drive multiple functions to produce robots, manipulators, and the like.

(II) Construction industry

As mentioned earlier, NiTi alloy shape memory alloys have various characteristics. Combined with the structure of NiTi alloy shape memory alloys, the system's damping can be enhanced and the dynamic response of the structure can be reduced to produce various forms of damping energy dissipation devices. You can also use nickel-titanium alloy shape memory alloys to design vibration isolators. The deformation of nickel-titanium alloy shape memory alloys increases the energy of deformation and displacement, prevents the transmission of structural seismic energy to the upper structure, thereby protecting the upper structure and truly enhancing the seismic performance of the structure. .

(3) Aerospace industry

In the aircraft hydraulic system, basically every aircraft needs to use 800 Ni-Ti alloy shape memory alloy joints. Since the 1970s, most American navy aircraft have used this fitting and there is no record of failure. In addition, nickel-titanium alloy shape memory alloys can also be used in spacecraft antennas and electromechanical actuators.

四 (4) Automotive industry

Nitinol shape memory alloy is mainly used in engine exothermic fan clutches, exhaust nozzles, diesel engine radiators, etc.

(5) Medical field

Ni-Ti alloy shape memory alloy has high mechanical properties and biocompatibility, which makes it widely used in medical field. Such as orthodontics, surgical plastic surgery, cardiovascular minimally invasive, etc .; thrombus filters are actually new products of nickel-titanium shape memory alloys; after being inserted into a vein, the straightened filter will gradually form a mesh over time. , Prevent more than 90% of blood clots from flowing to the heart, lungs and other organs. In addition, nickel-titanium alloy shape memory alloys are used in clinical trials for surgical sutures, artificial joints, artificial hearts, and the like.

3. Analysis of the development trend of shape memory alloys

一 (I) Iron-based shape memory alloy

Iron-based shape memory alloy has the advantages of strong processability and high cost performance, and has attracted much attention in many fields of society. Recent research work is mainly on the phase change mechanism and its influencing factors. The appropriate shape memory alloy is selected for distribution and exploration to improve the level of preparation technology and improve the performance of the alloy.

(2) Magnetic shape memory alloy

This shape memory alloy will generate strain under the great effect of magnetic field, and will increase the working frequency of the shape memory alloy from temperature-controlled state to magnetron state, giving full play to the function of magnetically driven shape memory alloy. Sensors and drive components made of magnetic shape memory alloys play an important role in the petroleum industry, electronics and aerospace industry.

(3) High-temperature shape memory alloy

Many common alloys can only be used at 100 degrees Celsius, and more and more shape memory alloys can be used at temperatures exceeding 100 degrees Celsius. For example, the shape memory alloy element in a nuclear reactor, its operating temperature has exceeded 600 degrees Celsius. Therefore, it has become an important trend to study the manufacture of high-temperature shape memory alloys. The use of high-temperature shape memory alloys in many fields has a good prospect.

24. Conclusion

This article analyzes the characteristics and functions of Ni-Ti alloy shape memory alloys. Although the current research and development of Ni-Ti alloy shape memory alloys is not thorough enough, with the widespread use of Ni-Ti alloy shape memory alloys in many fields Application, its performance will continue to develop and improve, nickel-titanium alloy shape memory alloy will play an increasing role.