Low-energy-consumption nickel-titanium shape memory alloy driving microwire and preparation method thereof

Abstract

The invention provides a low-energy-consumption nickel-titanium shape memory alloy driving microwire and a preparation method thereof, and relates to the field of shape memory alloys. During preparation, firstly, the shape memory alloy material is smelted to obtain a cast ingot, and then the cast ingot is sequentially subjected to forging, hot rolling, coiling, wire drawing, heat treatment and training to obtain a product. According to the scheme, on one hand, the heat treatment conditions are controlled, the treatment temperature is 400-500 DEG C, the heat treatment time is 1-30 min, and the grain size of nanocrystalline in the microfilament is controlled to be 30-100 nm; on the other hand, training conditions are controlled, namely, a load of 400-700 Mpa is applied to the shape memory alloy microwire, so that the shape memory alloy microwire is subjected to repeated phase change between martensite and austenite for 100-150 cycles, the electrical resistivity of the driving microwire is controlled to be 5.64-6.87 * 10 <-7 > omega.m, and finally the low-energy-consumption nickel-titanium shape memory alloy driving microwire is prepared. The driving microwire has the characteristics of low current input and high stroke output.

Description

Technical Field

[0001] The present invention relates to the technical field of shape memory alloys, and particularly relates to a low-energy consumption nickel-titanium shape memory alloy drive microfilament and a preparation method thereof. Background Art

[0002] The shape memory alloy drive microfilament is a new type of intelligent drive material. Compared with traditional electromagnetic motors, the shape memory alloy has the advantage of integrating the material and the device, which is conducive to the miniaturization of drive components. The shape memory alloy miniaturized drive component is a component driven by the Joule heat of an electric current. Therefore, reducing energy consumption is an aspect that many producers of electronic components and medical devices attach extra importance to. At present, the shape memory alloy drive microfilament has been used as a drive material in electronic components and medical devices, but there is no report on the solution to reduce the energy consumption of the shape memory alloy drive microfilament through the production process. Summary of the Invention

[0003] The purpose of the present invention is to provide a low-energy consumption nickel-titanium shape memory alloy drive microfilament and a preparation method thereof. By designing the process route of the drive microfilament and regulating the process parameters, the resistivity is controlled, and then a low-energy consumption nickel-titanium shape memory alloy drive microfilament with high stroke output under low current input is prepared.

[0004] To achieve the above purpose, the present invention proposes the following technical solutions:

[0005] In the first aspect, a low-energy consumption nickel-titanium shape memory alloy drive microfilament is proposed. The resistivity of the nickel-titanium shape memory alloy drive microfilament is 5.64 - 6.87×10 -7 Ω·m; the microstructure of the nickel-titanium shape memory alloy drive microfilament consists of amorphous and nanocrystals, and the grain size of the nanocrystals is 30 - 100 nm.

[0006] Further, the current required for the nickel-titanium shape memory alloy drive microfilament to reach a stable output strain of 3% is not greater than 60 mA.

[0007] Further, the nickel-titanium shape memory alloy drive microfilament is made by successively casting a shape memory alloy material into an ingot, forging and hot rolling it into a coil, drawing it into a microfilament, heat treating it, and training it. Among them, the heat treatment conditions are under inert gas protection, the treatment temperature is 400 - 500 °C, and the treatment time is 1 - 30 min.

[0008] Further, the standard of the training is to apply a load of 400 - 700 Mpa to the shape memory alloy microfilament after heat treatment, so that it undergoes 100 - 150 cycles of repeated phase transformation between martensite and austenite.

[0009] Further, the grain orientation of the microstructure of the nickel-titanium shape memory alloy drive microfilament is <111> / / axial direction.

[0010] In a second aspect, a method for preparing a low-energy-consumption nickel-titanium shape memory alloy-driven microfilament is proposed, including the following steps:

[0011] 1) Melting a shape memory alloy material to obtain an ingot;

[0012] 2) Forging and hot rolling the ingot into a coil to obtain a shape memory alloy wire;

[0013] 3) Drawing the shape memory alloy wire to obtain a drawn shape memory alloy microfilament;

[0014] 4) Heat-treating the shape memory alloy microfilament under the protection of an inert gas to obtain a heat-treated shape memory alloy microfilament; wherein, the process parameters of the heat treatment are: under the protection of an inert gas, the treatment temperature is 400 - 500 °C, and the heat treatment time is 1 - 30 min;

[0015] 5) Training the heat-treated shape memory alloy microfilament to obtain a low-energy-consumption nickel-titanium shape memory alloy-driven microfilament; wherein, the training standard is: applying a load of 400 - 700 Mpa to the heat-treated shape memory alloy microfilament to make it undergo 100 - 150 cycles of repeated phase transformation between martensite and austenite.

[0016] Further, the resistivity of the low-energy-consumption nickel-titanium shape memory alloy-driven microfilament prepared in step 5) is 5.64 - 6.87×10 -7 Ω·m.

[0017] Further, the microstructure of the low-energy-consumption nickel-titanium shape memory alloy-driven microfilament prepared in step 5) is composed of amorphous and nanocrystals. The grain size of the nanocrystals is 30 - 100 nm, and the grain orientation is <111> / / axial direction.

[0018] Further, the current required for the low-energy-consumption nickel-titanium shape memory alloy-driven microfilament prepared in step 5) to reach a stable output strain of 3% is not greater than 60 mA.

[0019] In a third aspect, an application of the above-mentioned low-energy-consumption nickel-titanium shape memory alloy-driven microfilament in the field of intelligent drive is proposed.

[0020] From the above technical solutions, the technical solutions of the present invention have obtained the following beneficial effects:

[0021] The low-energy consumption NiTi shape memory alloy-driven microfilament disclosed by the present invention and its preparation method. When preparing the microfilament, first melt the shape memory alloy material to obtain an ingot, then forge and hot-roll the ingot into a coil, and perform drawing after coiling to obtain a shape memory alloy microfilament. Finally, heat-treat and train the shape memory alloy microfilament under the protection of an inert gas. On the one hand, by controlling the heat treatment conditions, that is, controlling the treatment temperature at 400 - 500 °C and the heat treatment time at 1 - 30 min, the grain size of the nanocrystals inside the microfilament is controlled to be 30 - 100 nm; on the other hand, by controlling the training conditions of the wire, that is, applying a load of 400 - 700 Mpa to the shape memory alloy microfilament and making it undergo 100 - 150 cycles of repeated phase transformation between martensite and austenite, the resistivity of the driven microfilament is controlled to be 5.64 - 6.87*10 -7 Ω·m, and finally a low-energy consumption NiTi shape memory alloy-driven microfilament is prepared.

[0022] The current required for the low-energy consumption NiTi shape memory alloy-driven microfilament prepared in this application to reach a stable output strain of 3% is not greater than 60 mA, achieving the technical effect of high stroke output with low current input. Therefore, when applied in the field of intelligent driving, compared with the existing driven microfilaments, it can achieve the same strain with a smaller current, effectively reducing energy consumption.

[0023] It should be understood that all combinations of the foregoing concepts and additional concepts described in more detail below can be regarded as part of the inventive subject matter of the present disclosure as long as such concepts do not conflict with each other.

[0024] The foregoing and other aspects, embodiments, and features of the teachings of the present invention can be more fully understood from the following description in conjunction with the accompanying drawings. Other additional aspects of the present invention, such as the features and / or beneficial effects of exemplary embodiments, will be apparent from the following description or will be learned through the practice of specific embodiments in accordance with the teachings of the present invention. Description of the Drawings

[0025] The drawings are not drawn to scale according to actual reference objects. In the drawings, each identical or approximately identical component shown in each figure can be denoted by the same reference numeral. For the sake of clarity, not every component is labeled in each figure. Now, embodiments of various aspects of the present invention will be described by way of examples and with reference to the drawings, where:

[0026] Figure 1 It is a TEM image of the grain size of the driven microfilament prepared in Example 1 of the present invention;

[0027] Figure 2 It is the stable output strain of the driven microfilament prepared in Example 1 of the present invention under different current conditions;

[0028] Figure 3The stable output strain of the driving microfilament prepared in Comparative Example 1 of the present invention under different current conditions. Detailed implementation manners

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the described embodiments of the present invention without creative efforts fall within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein shall have the ordinary meanings understood by those of ordinary skill in the art to which the present invention pertains.

[0030] The terms "first", "second", and similar terms used in the specification and claims of this patent application of the present invention do not denote any order, quantity, or importance, but are only used to distinguish different components. Similarly, unless the context clearly indicates otherwise, the singular forms "a", "an", or "the" and similar terms do not denote a limitation of quantity, but rather indicate the presence of at least one. The terms "comprising" or "including" and similar terms are intended to mean that the elements or items appearing before "comprising" or "including" cover the features, wholes, steps, operations, elements, and / or components listed after "comprising" or "including", and do not exclude the existence or addition of one or more other features, wholes, steps, operations, elements, components, and / or their combinations. The terms "upper", "lower", "left", "right", etc. are only used to represent relative positional relationships, and when the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0031] When the shape memory alloy micro-miniature driving component is used in electronic components and medical devices, it relies on the Joule heat generated by current to drive and achieve application functions. With the increasing requirements for low energy consumption and high output of products in social development, there is no reported solution in the prior art to reduce the application energy consumption of the shape memory alloy driving microfilament through the production process. Moreover, the shape memory alloy driving microfilament with ultra-high stability disclosed in the existing patent application 2023113571575 also adjusts the heat treatment conditions and wire training process of the shape memory alloy wire. However, when such a wire is used as a driving microfilament in specific applications, although it can exhibit corresponding performance, such as performance stability, it cannot reduce energy consumption. Therefore, such a wire is not applicable in some scenarios with strict energy application requirements, and a new low-energy consumption shape memory alloy wire needs to be proposed to meet the increasingly strict low-energy consumption requirements.

[0032] Specifically, the preparation method of the low-energy-consumption nickel-titanium shape memory alloy-driven microfilament includes the following steps: 1) Melting the shape memory alloy material to obtain an ingot; 2) Forging and hot rolling the ingot into a coil to obtain a shape memory alloy wire; 3) Drawing the shape memory alloy wire to obtain a drawn shape memory alloy microfilament; A large amount of plastic deformation will occur during the wire drawing and forming process of the shape memory alloy wire, making its microstructure composed of amorphous and nanocrystals; 4) Heat-treating the shape memory alloy microfilament under inert gas protection to obtain a heat-treated shape memory alloy microfilament; Among them, the process parameters of the heat treatment are: under inert gas protection, the treatment temperature is 400-500 °C, and the heat treatment time is 1-30 min; During the heat treatment process, the microstructure recovers, and the phenomena of recrystallization and grain growth occur. By controlling the temperature and time of the heat treatment, the grain size and grain orientation distribution can be controlled; The larger the grain size, the fewer the number of grain boundaries that hinder the free movement of electrons, and the lower the resistivity of the material; The more concentrated the grain orientation distribution, the smoother the free movement of electrons, and the lower the resistivity of the material. 5) Training the heat-treated shape memory alloy microfilament to obtain a low-energy-consumption nickel-titanium shape memory alloy-driven microfilament; Among them, the training standard is: applying a load of 400-700 Mpa to the heat-treated shape memory alloy microfilament, and making it undergo 100-150 cycles of repeated phase transformation between martensite and austenite. The process of the shape memory alloy microfilament changing from martensite to austenite and then to martensite is 1 phase transformation cycle; The training process will induce the reorientation of grains inside the shape memory alloy microfilament, so it can be used to regulate the resistivity of the shape memory alloy microfilament.

[0033] The resistivity of the above-prepared nickel-titanium shape memory alloy-driven microfilament is 5.64-6.87*10 -7 Ω·m. The microstructure of the nickel-titanium shape memory alloy-driven microfilament is composed of amorphous and nanocrystals. The grain size of the nanocrystals is 30-100 nm, and the grain orientation is <111> / / axial; And the current required for the nickel-titanium shape memory alloy-driven microfilament to reach a stable output strain of 3% is not greater than 60 mA. Through the above heat treatment process, the present invention controls the grain size of the nanocrystals of the shape memory alloy microfilament, and at the same time controls the resistivity of the shape memory alloy microfilament to be 5.64-6.87*10 -7 Ω·m by controlling the training conditions, and finally obtains a low-energy-consumption nickel-titanium shape memory alloy-driven microfilament, which can stably output strain for a long time.

[0034] The following specifically introduces the low-energy-consumption nickel-titanium shape memory alloy-driven microfilament and its preparation method disclosed by the present invention in combination with the specific embodiments shown in the accompanying drawings.

[0035] Example 1

[0036] 1) Melting the shape memory alloy material to obtain an ingot; 2) Forging and hot rolling the ingot into a coil to obtain shape memory alloy wire; 3) Drawing the shape memory alloy wire to obtain a shape memory alloy micro-wire with a diameter of 25 μm; 4) Heat-treating the shape memory alloy micro-wire under inert gas protection to obtain the heat-treated shape memory alloy micro-wire; wherein, the process parameters of the heat treatment are: under inert gas protection, the treatment temperature is 450 °C, and the heat treatment time is 5 min; 5) Training the heat-treated shape memory alloy micro-wire to obtain a low-energy consumption nickel-titanium shape memory alloy drive micro-wire; wherein, the training standard is: applying a load of 500 Mpa to the heat-treated shape memory alloy micro-wire to make it undergo 110 cycles of repeated phase transformation between martensite and austenite. The microstructure of the drive micro-wire was observed by transmission electron microscopy, as Figure 1 described, the grain size is between 30 - 100 nm.

[0037] Examples 2 - 4, Comparative Examples 1 - 2 are different from Example 1 only in the heat treatment conditions, and the training conditions remain unchanged during preparation to obtain several drive micro-wires; the drive micro-wires obtained in each example and comparative example were tested for the stroke under current drive; the test conditions and results are shown in Table 1 below. Since there is an attenuation behavior in the output strain during the test, the current required to reach a stable output strain of 3% is used here to evaluate the energy consumption, that is, the strain that the drive micro-wire can continuously and stably output during service. The resistivity determines the Joule heat drive behavior under current input. As the material serves, under the action of external forces, the grain size and grain orientation of the material change, causing a change in resistivity and thus a change in energy consumption.

[0038] Table 1 Influence of different heat treatment conditions on the energy consumption of drive micro-wires

[0039]

[0040] Simultaneously measure the stable output strain of the wire with a length of 100 mm after energization under different current conditions of 25 - 100 mA for Example 1 and Comparative Example 1, and the results are as Figure 2 and Figure 3 shown.

[0041] Examples 5 - 7, Comparative Examples 3 - 4 are different from Example 1 only in the training conditions, and the heat treatment conditions remain unchanged during preparation to obtain several drive micro-wires; the drive micro-wires obtained in each example and comparative example were tested for the stroke under current drive; the test conditions and results are shown in Table 2 below.

[0042] Table 2 Influence of different training conditions on the energy consumption of drive micro-wires

[0043]

[0044] As shown in Table 1 and Table 2 comprehensively, compared with Comparative Examples 1-4, the current required for the driving microfilaments of Examples 1-7 to reach a stable output strain of 3% is smaller, achieving the purpose of reducing energy consumption. The heat treatment temperature of Comparative Example 1 is too low, resulting in a grain size of less than 30 nm and too high resistivity of the wire; the heat treatment temperature of Comparative Example 2 is too high, resulting in a grain size of more than 100 nm and too low resistivity of the wire; the heat treatment conditions of Examples 1-4 are appropriate, fully controlling the grain size between 30-100 nm, and the resistivity of the wire is appropriate; the reason is that the wire with too low resistivity has large grains and few grain boundaries inside. Although the wire with large grains can achieve the effect of reducing energy consumption in the early stage of use, with the extension of the use time, irreversible deformations such as dislocation slip will occur in the wire, resulting in a continuous reduction in the volume of the wire that can undergo phase transformation, and then leading to the attenuation of the output strain during driving. Therefore, it is necessary to control the resistivity of the wire within an appropriate range to maintain the stable output performance of the wire. The training load of Comparative Example 3 is too small, resulting in insufficient training, and the wire texture does not form a strong <111> / / axial texture. Eventually, the resistivity of the wire is too high, and the current required when the output strain is 3% is large; the training load of Comparative Example 4 is too large, resulting in overtraining of the wire. A strong <111> / / axial texture is formed inside the material, but overtraining leads to plastic deformation, that is, irreversible deformation, resulting in the gradual attenuation of the output strain of the driving microfilament, and finally resulting in a small stable strain output by the wire; Examples 1, 5-7 perform appropriate training on the wire, enabling the wire to have a strong <111> / / axial texture while maintaining no plastic deformation inside the wire and no irreversible strain, ensuring that the driving microfilament can continuously and stably output the required strain during use.

[0045] When the low-energy-consumption NiTi shape memory alloy driving microfilament prepared in the above examples is applied in the field of intelligent driving, such as being applied to make a microdriver, because the resistivity of this shape memory alloy driving microfilament is between 5.64 - 6.87×10 -7 Ω·m, while the resistivity of the existing driving microfilament is between 5.00 - 5.60×10 -7 Ω·m or 6.90 - 7.50×10 -7 Ω·m, the energy consumption of this microdriver is reduced by about 40% when applied.

[0046] Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Those with ordinary knowledge in the technical field to which the present invention pertains can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to what is defined by the claims.

Claims

1. A low-energy nickel-titanium shape memory alloy-driven microfilament, characterized in that, The resistivity of the NiTi shape memory alloy-driven micro wire is 5.64 - 6.87 * 10 -7 Ω·m; the microstructure of the NiTi shape memory alloy-driven micro wire consists of amorphous and nanocrystals, and the grain size of the nanocrystals is 30 - 100 nm.

2. The low-energy consumption nickel-titanium shape memory alloy-driven micro wire according to claim 1, wherein The current required for the NiTi shape memory alloy to drive the microfilament to reach a stable output strain of 3% is not greater than 60 mA.

3. The low-energy-consumption nickel-titanium shape memory alloy-driven microfilament according to claim 1, wherein The NiTi shape memory alloy drives the microfilament and is successively made by casting the shape memory alloy material into an ingot, forging and hot rolling it into a coil, drawing it into a microfilament, heat treatment, and training; among them, the heat treatment conditions are under inert gas protection, the treatment temperature is 400 - 500 °C, and the treatment time is 1 - 30 min.

4. The low-energy-consumption nickel-titanium shape memory alloy-driven micro wire according to claim 3, characterized in that, The standard of the training is to apply a load of 400 - 700 Mpa to the shape memory alloy microfilament after heat treatment, so that it undergoes 100 - 150 cycles of repeated phase transformation between martensite and austenite.

5. The low-energy-consumption nickel-titanium shape memory alloy-driven micro wire according to claim 1, wherein The grain orientation of the microstructure of the NiTi shape memory alloy driven microfilament is <111> / / axial direction.

6. A preparation method of a low-energy-consumption nickel-titanium shape memory alloy-driven microfilament, characterized in that, It includes the following steps: 1) Melting the shape memory alloy material to obtain an ingot; 2) Forging and hot rolling the ingot into a coil to obtain a shape memory alloy wire; 3) Drawing the shape memory alloy wire to obtain a drawn shape memory alloy microfilament; 4) Heat-treating the shape memory alloy microfilament under inert gas protection to obtain a heat-treated shape memory alloy microfilament; among them, the process parameters of the heat treatment are: under inert gas protection, the treatment temperature is 400 - 500 °C, and the heat treatment time is 1 - 30 min; 5) Training the heat-treated shape memory alloy microfilament to obtain a low-energy-consumption NiTi shape memory alloy driven microfilament; among them, the training standard is: applying a load of 400 - 700 Mpa to the heat-treated shape memory alloy microfilament, so that it undergoes 100 - 150 cycles of repeated phase transformation between martensite and austenite.

7. The preparation method of the low-energy-consumption nickel-titanium shape memory alloy-driven microfilament according to claim 6, wherein, The resistivity of the low-energy-consumption nickel-titanium shape memory alloy drive micro wire prepared in the step 5) is 5.64 - 6.87×10 -7 Ω·m.

8. The preparation method of the low-energy-consumption nickel-titanium shape memory alloy-driven microfilament according to claim 6, wherein The microstructure of the low-energy-consumption NiTi shape memory alloy driven microfilament prepared in step 5) is composed of amorphous and nanocrystals. The grain size of the nanocrystals is 30 - 100 nm, and the grain orientation is <111> / / axial direction.

9. The preparation method of the low-energy-consumption nickel-titanium shape memory alloy-driven microfilament according to claim 6, characterized in that The current required for the low-energy-consumption NiTi shape memory alloy driven microfilament prepared in step 5) to reach a stable output strain of 3% is not greater than 60 mA.

10. Application of a low-energy-consumption NiTi shape memory alloy driven microfilament according to any one of claims 1 - 5 in the field of intelligent drive.

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