Shape memory material and processing method thereof, driving element and driving device

Abstract

The invention provides a shape memory material, the shape memory material has an R phase change two-way memory effect, the shape memory material comprises an R phase and a B19'martensite lath, the R phase and the B19 'martensite lath have a semi-coherent interface, the semi-coherent interface has an internal stress field, and the internal stress field is used for inducing the R phase change two-way memory effect. The invention further provides a processing method of the shape memory material, a driving element and a driving device. The shape memory material disclosed by the invention has an R phase change two-way memory effect, relatively low thermal hysteresis, high response speed, short recovery time, relatively high cycle frequency, relatively long cycle life and relatively high stability.

Description

Technical Field

[0001] The present application relates to the field of shape memory materials, and in particular to a shape memory material and a processing method thereof, a driving element prepared from the shape memory material, and a driving device using the driving element. Background Art

[0002] Shape memory alloy drive devices or actuators have the advantages of high unit energy density, compact size, lightweight system, no noise, no electromagnetic radiation, etc., and are an important alternative to linear motors and electromagnetic actuators. The structure of shape memory alloy devices usually includes three parts: drive elements (shape memory alloy drive wires, sheets, etc.), return mechanisms, and power supplies. Among them, the return mechanism is mainly a spring, which plays a resetting role. This shape and alloy device requires a return mechanism, which is bloated and difficult to achieve maximum lightweight.

[0003] In response to the above problems, two-way shape memory alloy materials have been developed. By utilizing the two-way memory effect, the drive element can recover during the cooling process without the assistance of a recovery structure (i.e., a spring). The two-way memory alloy materials commonly developed all occur during the B2-B19' martensitic phase transformation process, and the local plastic strain brought by the pre-strain induces the internal stress field to achieve spontaneous recovery. However, B2-B19' martensite usually has a large thermal hysteresis, which leads to a slow response of the shape memory material and a long recovery process. Summary of the invention

[0004] In view of this, in order to solve at least one of the above defects, an embodiment of the present application provides a shape memory material, which has an R-phase change two-way memory effect. The shape memory material has low thermal hysteresis, fast response, short recovery time, high cycle frequency, and high cycle life and stability.

[0005] In addition, the embodiments of the present application also provide a method for processing the shape memory material, a driving element using the shape memory material, and a driving device using the driving element.

[0006] A first aspect of an embodiment of the present application provides a shape memory material having a two-way memory effect of an R-phase transformation. The shape memory material comprises an R-phase and a B19' martensite lath, and a semi-coherent interface exists between the R-phase and the B19' martensite lath. An internal stress field exists at the semi-coherent interface, and the internal stress field is used to induce a two-way phase transformation of the R-phase.

[0007] By introducing high-density and uniformly distributed R-phase and B19' martensite laths into the shape memory material, and creating an internal stress field at the semi-coherent interface between the R-phase and the B19' martensite laths, the internal stress field is the key to inducing the R-phase transformation two-way memory effect, so that the shape memory material can achieve the R-phase transformation two-way memory effect. The R-phase transformation two-way memory effect has low thermal hysteresis, fast response speed, short recovery time, and high cycle frequency, and the shape memory material has high cycle life and stability.

[0008] Specifically, the cycle frequency of the shape memory material is above 10Hz, further, the cycle frequency is above 11Hz, and further, the cycle frequency is above 12Hz, far exceeding the traditional B2-B19' two-way memory effect material (the cycle frequency is usually not more than 1Hz). And at the above cycle frequencies, the shape memory material has high stability and a cycle life of more than one million times.

[0009] In combination with the first aspect, in some possible embodiments, the average grain size of the R phase is 20 nm to 100 nm.

[0010] The average grain size of the R phase is a key factor affecting the R phase change response temperature, the recoverable strain of the shape memory material, and the cycle life. If the average grain size of the R phase is too small, less than 20nm, the recoverable strain of the shape memory material is too small, unstable, and has a short life, making it difficult to apply; if the average grain size of the R phase is too large, exceeding 100nm, the response temperature range of the R phase change is too wide, the phase change response is slow, the deformation recovery time is too long, the cycle frequency is low, and it is difficult to accurately control the phase change temperature of the R phase. Therefore, the embodiment of the present application can control the average grain size of the R phase to be between 20nm and 100nm. On the one hand, the recoverable strain of the shape memory material can be increased, the cycle life and stability can be improved; on the other hand, it is convenient to accurately control the phase change temperature of the R phase, so that the phase change temperature is within a reasonable range, reduce the thermal hysteresis of the R phase change, and then increase the phase change response speed, shorten the deformation recovery time, and increase the cycle frequency of the shape memory material. Further, the average grain size may be 20nm to 80nm, further, the average grain size may be 20nm to 50nm, further, the average grain size may be 25nm to 50nm, further, the average grain size may be 25nm to 40nm. Exemplarily, the average grain size of the R phase may be 20nm, 25nm, 30nm, 35nm, 40nm, 45nm, 50nm, 55nm, 60nm, 65nm, 70nm, 75nm, 80nm, 85nm, 90nm, 95nm, 100nm or a value between any two of the above values.

[0011] In combination with the first aspect, in some possible embodiments, the recoverable strain of the shape memory material is 0.8% to 1.2%.

[0012] The recoverable strain of the conventional R phase is small, the life is short, and it may even fail to meet the application requirements. The embodiment of the present application generates a relatively small internal stress field accompanying the phase interface introduced during the R-B19' phase transition, and regulates the average grain size and crystal density of the R phase. The recoverable strain of the R phase in the shape memory material can reach 0.8% to 1.2%, which can meet a variety of application requirements and has a long cycle life.

[0013] In combination with the first aspect, in some possible embodiments, the operating temperature of the shape memory material is -40°C to 100°C.

[0014] This shape memory material has a wide operating temperature range, with a temperature span of about 140°C. It has a wide span and a wide range of application scenarios. It can be used in scenarios with various temperature requirements and has high commercial utilization value.

[0015] A second aspect of the embodiments of the present application provides a driving element, wherein the driving element is made of a shape memory material, and the shape memory material is the shape memory material described in the first aspect of the embodiments of the present application.

[0016] The driving element prepared using the aforementioned shape memory material with R-phase change two-way memory effect can achieve two-way memory effect, has low thermal hysteresis, fast response speed, short deformation recovery time, high cycle frequency, and at the same time has high cycle life and stability.

[0017] A third aspect of the embodiments of the present application provides a driving device (or actuator), which may include the aforementioned driving element.

[0018] In combination with the third aspect, in some possible embodiments, the driving device may further include a power supply, and the power supply is used to induce the aforementioned driving element to undergo a phase transition. For example, the power supply may heat the driving element to cause a temperature change, thereby causing a phase transition.

[0019] It can be understood that the driving device may further include a heat source, and the driving element may induce phase change through the heat source.

[0020] The driving element made of the shape memory material with the R phase change two-way memory effect does not need to be equipped with a recovery element, which simplifies the structure of the driving device and is conducive to the lightweight of the driving device. At the same time, it can also improve the driving frequency, device life and device stability of the driving device.

[0021] A fourth aspect of the present application provides a method for processing a shape memory material, the method comprising:

[0022] Annealing the shape memory material in a cold-drawn state, wherein the annealing temperature is 650-750° C. and the time is less than 5 hours; and

[0023] The annealed shape memory material is subjected to aging treatment, wherein the temperature of the aging treatment is 230-280° C. and the time is 5-40 hours. The shape memory material after the aging treatment has an R phase change two-way memory effect.

[0024] The key to the two-way shape memory effect is to create an internal stress field in the matrix to ensure that the phase change path has a unique orientation. The embodiment of the present application controls the process parameters of annealing and aging, thereby regulating the type of crystals, grain size, crystal density and crystal distribution uniformity in the shape memory material to form a high-density, uniformly distributed R phase with a nano-domain structure; at the same time, a semi-coherent interface with a stress field can be introduced during the R-B19' phase change process. The internal stress of the internal stress field is small. This small internal stress field is the key to the shape memory material to obtain the two-way memory effect of the R phase change. It will not cause plastic deformation of the R phase, nor will it stabilize the B19' martensite lath to destroy the R phase change path, so that the R phase change two-way memory effect of the shape memory material has low thermal hysteresis, fast phase change response, short recovery time, high cycle frequency, and high cycle life and stability.

[0025] Specifically, during the annealing process, controlling the annealing temperature and a shorter annealing time are the key to controlling the average grain size of the R phase, and the average grain size of the R phase can be controlled within the range of 20nm to 100nm to improve the cycle frequency, cycle life and deformation stability of the shape memory material. The annealing temperature can further be 680 to 720°C. Exemplarily, the annealing temperature can be 650°C, 660°C, 670°C, 680°C, 690°C, 700°C, 710°C, 720°C, 730°C, 740°C, 750°C or a value between any two of the above values. The annealing time may further be 1 to 4.8 hours, further may be 1 to 4.5 hours, further may be 1 to 4 hours, further may be 3 to 4 hours. Exemplarily, the annealing time may be 1 hour, 1.5 hours, 1.8 hours, 2 hours, 2.5 hours, 2.8 hours, 3 hours, 3.5 hours, 3.8 hours, 4 hours, 4.3 hours, 4.5 hours, 4.8 hours, 4.9 hours or a value between any two of the above values.

[0026] Specifically, during the aging treatment, by controlling the temperature and time of the low-temperature aging process, the position of the phase change temperature point of the shape memory material can be adjusted to obtain a suitable phase change temperature range, so as to reduce the thermal hysteresis of the shape memory material, increase the phase change response speed, shorten the deformation recovery time, and thus increase the cycle frequency. The temperature of the aging treatment can further be 230 to 270°C, and can further be 250 to 270°C. Exemplarily, the temperature of the aging treatment can be 230°C, 235°C, 240°C, 245°C, 250°C, 255°C, 260°C, 265°C, 270°C, 275°C, 280°C or a value between any two of the above values. The aging treatment time may further be 8 to 30 hours, and may further be 10 to 20 hours. Exemplarily, the aging treatment time may be 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours, 19 hours, 20 hours, 21 hours, 22 hours, 23 hours, 24 hours, 25 hours, 26 hours, 27 hours, 28 hours, 29 hours, 30 hours, 31 hours, 32 hours, 33 hours, 34 hours, 35 hours, 36 hours, 37 hours, 38 hours, 39 hours, 40 hours, or a value between any two of the above values.

[0027] In conjunction with the second aspect, in some possible embodiments, after the aging treatment step, the processing method further includes:

[0028] The shape memory material after aging treatment is subjected to pre-strain treatment.

[0029] In some embodiments, the strain amount after pre-strain treatment is 5% to 9%, and an exemplary strain amount after pre-strain treatment can be 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9% or a value between any two of the above values; the strain amount after recovery is 0.8% to 1.2%, and an exemplary strain amount after recovery is 0.8%, 0.9%, 0.95%, 1%, 1.1%, 1.2% or a value between any two of the above values.

[0030] By pre-straining the shape memory material after high-temperature annealing and low-temperature aging, no plastic deformation occurs during the pre-straining process, which is beneficial for the shape memory material to obtain a recoverable strain of about 1%, thereby improving the cycle life and cycle stability of the shape memory material. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A processing flow chart of a shape memory material provided in one embodiment of the present application.

[0032] Figure 2Figures (a) to (h) are transmission electron microscope images of the shape memory material provided in one embodiment of the present application.

[0033] Figure 3 A transmission electron microscope image of a shape memory material provided in another embodiment of the present application.

[0034] Figure 4 A curve showing the relative relationship between temperature and strain of a shape memory material provided in one embodiment of the present application after multiple cycles.

[0035] Figure 5 A schematic diagram of a driving element provided in accordance with an embodiment of the present application.

[0036] Figure 6 A schematic diagram of a driving device provided in accordance with an embodiment of the present application.

[0037] Figure 7 This is a displacement time curve of the shape memory alloy wire provided in Example 1 of the present application.

[0038] Figure 8 This is a displacement time curve of the shape memory alloy wire provided in Example 2 of the present application.

[0039] Fig. 9 This is a displacement-time curve diagram of the shape memory alloy wire provided in Example 3 of the present application.

[0040] Fig.10 This is a displacement time curve of the shape memory alloy wire provided in Comparative Example 1 of the present application.

[0041] Main component symbols

[0042] Driving element 100

[0043] Drive device 200

[0044] Power 201 DETAILED DESCRIPTION

[0045] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application.

[0046] The terms used in the following embodiments are only for the purpose of describing specific embodiments and are not intended to be used as limitations on the present application. As used in the specification and appended claims of the present application, the singular expressions "a", "an", "above", "the" and "this" are intended to also include expressions such as "one or more", unless there is a clear contrary indication in the context.

[0047] References to "one embodiment" or "some embodiments" etc. described in this specification mean that a particular feature, structure or characteristic described in conjunction with the embodiment is included in one or more embodiments of the present application. Thus, the phrases "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. that appear at different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0048] Unless otherwise specified, the data range values ​​recorded in this application should include the end values.

[0049] In addition, the following terms in the embodiments of the present application are explained below.

[0050] Pre-strain: refers to the constant strain and constant value tensile deformation performed before the shape memory effect test.

[0051] Thermal drive cycle frequency: The frequency of the shape memory alloy drive cycle is determined based on the cycle time of heating and cooling. Generally, the phase change of shape memory alloy has a large thermal hysteresis and is extremely dependent on the cooling rate, so the frequency is generally low; the R phase change double-pass effect achieved by the present invention has a very small thermal hysteresis, so the cycle frequency is greatly increased. This is also a major advantage of the present invention.

[0052] The embodiment of the present application provides a shape memory material, which has an R phase change two-way memory effect, has low thermal hysteresis, and has high cycle life and stability. The shape memory material can be used as a driving element in devices such as sensors and smart actuators, but is not limited thereto.

[0053] The shape memory material of the embodiment of the present application has a two-way memory effect of R-phase transformation. The shape memory material contains an R phase and a B19' martensite lath, and there is a semi-coherent interface between the R phase and the B19' martensite lath (that is, the phase interface between the R phase and the B19' martensite lath is a semi-coherent interface). There is an internal stress field at the semi-coherent interface, and the internal stress field is used to induce the R phase to undergo a two-way phase transformation.

[0054] The key to the two-way shape memory effect is to create an internal stress field in the matrix to ensure that the phase transformation path has a unique orientation. The traditional technology is to obtain the B2-B19' two-way shape memory effect by means of plastic deformation. The huge stress field brought about by plastic deformation can ensure the uniqueness of the B19' martensite phase transformation path. However, if large plastic deformation is performed during the R phase transformation, it will not only cause a large number of dislocations, but also cause a large amount of B19' martensite to stabilize, destroying the phase transformation path of the R phase. Therefore, in the embodiment of the present application, plastic deformation is not introduced, and a semi-coherent phase interface is introduced during the R-B19' phase transformation process. At the same time, the semi-coherent interface generates a relatively small internal stress field, and by controlling the strain amount, the shape memory material has the R phase transformation two-way memory effect.

[0055] In some embodiments, the average grain size of the R phase is 20nm to 100nm. The average grain size of the R phase is a key factor affecting the R phase change response temperature, the recoverable strain of the shape memory material and the cycle life. If the average grain size of the R phase is too small, less than 20nm, the recoverable strain of the shape memory material is too small, unstable and short-lived, and it is difficult to apply; if the average grain size of the R phase is too large, exceeding 100nm, the response temperature range of the R phase change is too wide, the phase change response is slow, the deformation recovery time is too long, the cycle frequency is low, and it is difficult to accurately control the phase change temperature of the R phase. Therefore, the embodiment of the present application can control the average grain size of the R phase between 20nm and 100nm. On the one hand, the recoverable strain of the shape memory material can be increased, the cycle life and stability can be improved; on the other hand, it is convenient to accurately control the phase change temperature of the R phase, so that the phase change temperature is within a reasonable range, reduce the thermal hysteresis of the R phase change, and then increase the phase change response speed, shorten the deformation recovery time, and increase the cycle frequency of the shape memory material. Further, the average grain size may be 20nm to 80nm, further, the average grain size may be 20nm to 50nm, further, the average grain size may be 25nm to 50nm, further, the average grain size may be 25nm to 40nm. Exemplarily, the average grain size of the R phase may be 20nm, 25nm, 30nm, 35nm, 40nm, 45nm, 50nm, 55nm, 60nm, 65nm, 70nm, 75nm, 80nm, 85nm, 90nm, 95nm, 100nm or a value between any two of the above values.

[0056] In some embodiments, the recoverable strain of the shape memory material is about 1%, specifically 0.8% to 1.2%. The recoverable strain of the conventional R phase is small, the life is short, and it may even fail to meet the application requirements. The embodiment of the present application can achieve a recoverable strain of the R phase in the shape memory material of 0.8% to 1.2% by introducing a relatively small internal stress field accompanied by the phase interface introduced during the R-B19' phase transition, and by regulating the average grain size and crystal density of the R phase, which can meet a variety of application requirements and has a long cycle life.

[0057] In some embodiments, the use temperature of the shape memory material is -40°C to 100°C. The shape memory material has a wide use temperature range, a temperature span of about 140°C, a wide span, and a wide range of application scenarios. It can be applied to scenarios with various temperature requirements and has high commercial utilization value.

[0058] In some embodiments, the shape memory material may be a shape memory alloy, wherein the shape memory alloy is a high nickel formula, and the shape memory material comprises the following components by atomic percentage:

[0059] Nickel (Ni): 50.2%~51%; Titanium (Ti): 49%~49.8%.

[0060] The embodiment of the present application introduces R-phase and B19' martensite laths into the shape memory material, and creates a relatively small internal stress field at the semi-coherent interface between the R-phase and the B19' martensite laths. The internal stress field is the key to inducing the R-phase transformation two-way memory effect, so that the shape memory material can achieve the R-phase transformation two-way memory effect. The R-phase transformation two-way memory effect has low thermal hysteresis, fast response speed, short recovery time, and high cycle frequency, and the shape memory material has high cycle life and stability.

[0061] Specifically, the cycle frequency of the shape memory material is above 10Hz, further, the cycle frequency is above 11Hz, and further, the cycle frequency is above 12Hz, far exceeding the traditional B2-B19' two-way memory effect material (the cycle frequency is usually not more than 1Hz). And at the above cycle frequencies, the shape memory material has high stability and a cycle life of more than one million times.

[0062] See also Figure 1 Based on the same inventive concept, the present application also provides a processing method for the aforementioned shape memory material, the processing method comprising:

[0063] Step S1, annealing the shape memory material in a cold-drawn state, wherein the annealing temperature is 650-750° C. and the time is less than 5 hours.

[0064] During the annealing process, controlling the annealing temperature and a shorter annealing time are the key to controlling the average grain size of the R phase, which can control the average grain size of the R phase within the range of 20nm to 100nm to form a high-density and uniformly distributed R phase with a nano-domain structure, thereby improving the cycle frequency, cycle life and deformation stability of the shape memory material. The annealing temperature can further be 680 to 720°C. Exemplarily, the annealing temperature can be 650°C, 660°C, 670°C, 680°C, 690°C, 700°C, 710°C, 720°C, 730°C, 740°C, 750°C or a value between any two of the above values. The annealing time may further be 1 to 4.8 hours, further may be 1 to 4.5 hours, further may be 1 to 4 hours, further may be 3 to 4 hours. Exemplarily, the annealing time may be 1 hour, 1.5 hours, 1.8 hours, 2 hours, 2.5 hours, 2.8 hours, 3 hours, 3.5 hours, 3.8 hours, 4 hours, 4.3 hours, 4.5 hours, 4.8 hours, 4.9 hours or a value between any two of the above values.

[0065] Step S2, performing aging treatment on the annealed shape memory material, wherein the aging treatment temperature is 230-280° C., and the time is 5-40 hours. The shape memory material after the aging treatment has an R phase change two-way memory effect.

[0066] Specifically, the low-temperature aging process can induce fluctuations in the size and density of the R phase and B19' martensite laths, thereby regulating the R phase transformation temperature range. During the aging treatment, by specifically controlling the temperature and time of the low-temperature aging process, the position of the phase transformation temperature point of the shape memory material can be regulated to obtain a suitable phase transformation temperature range, thereby reducing the thermal hysteresis of the shape memory material, increasing the phase transformation response speed, shortening the deformation recovery time, and thereby increasing the cycle frequency. The temperature of the aging treatment can further be 230 to 270°C, and can further be 250 to 270°C. Exemplarily, the temperature of the aging treatment can be 230°C, 235°C, 240°C, 245°C, 250°C, 255°C, 260°C, 265°C, 270°C, 275°C, 280°C or a value between any two of the above values. The aging treatment time may further be 8 to 30 hours, and may further be 10 to 20 hours. Exemplarily, the aging treatment time may be 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours, 19 hours, 20 hours, 21 hours, 22 hours, 23 hours, 24 hours, 25 hours, 26 hours, 27 hours, 28 hours, 29 hours, 30 hours, 31 hours, 32 hours, 33 hours, 34 hours, 35 hours, 36 hours, 37 hours, 38 hours, 39 hours, 40 hours, or a value between any two of the above values.

[0067] In some embodiments, after step S2, the processing method further includes:

[0068] Step S3, performing pre-strain treatment on the shape memory material.

[0069] In some embodiments, the pre-strain treatment is a constant strain and fixed value stretching deformation performed before the shape memory effect test of the shape memory material. The strain after the pre-strain treatment is 5% to 9%. Exemplary strain after the pre-strain treatment can be 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9% or a value between any two of the above values; the strain after recovery is about 1%, specifically 0.8% to 1.2%. Exemplary strain after recovery is 0.8%, 0.9%, 0.95%, 1%, 1.1%, 1.2% or a value between any two of the above values.

[0070] By pre-straining the shape memory material after high-temperature annealing and low-temperature aging, no plastic deformation occurs during the pre-straining process, which is conducive to the shape memory material obtaining a recoverable strain of about 1%, thereby improving the cycle life and cycle stability of the shape memory material.

[0071] The key to the two-way shape memory effect is to create an internal stress field in the matrix to ensure that the phase change path has a unique orientation. The embodiment of the present application does not introduce plastic deformation. By controlling the process parameters of annealing and aging, the type of crystals, grain size, crystal density and crystal distribution uniformity in the shape memory material are regulated to form a high-density, uniformly distributed R phase with a nano-domain structure; at the same time, a semi-coherent interface with a stress field can be introduced during the R-B19' phase change process. The internal stress of the internal stress field is small. This small internal stress field is the key to the shape memory material to obtain the two-way memory effect of the R phase change. It will not cause plastic deformation of the R phase, nor will it stabilize the B19' martensite lath to destroy the R phase change path, so that the R phase change two-way memory effect of the shape memory material has low thermal hysteresis, fast phase change response, short recovery time, high cycle frequency, and high cycle life and stability.

[0072] Specifically, Figure 2 Figures (a) to (h) in the figure are transmission electron microscope images of the shape memory material processed by the above method in one embodiment of the present application. The microstructure of the SMA material is photographed by a transmission electron microscope, wherein: Figure 2 Figures (a) and (f) are bright field images. Figure 2 Figures (b) to (e) as well as (g) and (h) are dark field images. Figure 2 In (a), the B19' phase is a B19' martensite lath, and R1 and R2 represent two R phases; Figure 2 The two circles in (c) are R phase. Figure 2 It can be seen from Figures (a) to (h) that there are R phase and B19' martensite laths in the shape memory material, and the R phase has a higher density and is more evenly distributed; there is no dislocation at the phase interface between the R phase and the B19' martensite lath, which is conducive to the formation of a unique R phase transformation two-way memory path.

[0073] like Figure 3 FIG. 1 is a transmission electron microscope image of a shape memory material obtained by using different aging treatment temperatures in another embodiment of the present invention. Figure 3 It can also be seen from Figures (a) to (c) that after being treated at different aging temperatures, the R phase in the obtained shape memory material has a higher density and is more evenly distributed. The embodiment of the present application can further improve the R phase change response speed of the shape memory material, shorten the deformation recovery time, and thus increase the cycle frequency, and can also further improve the cycle life and stability of the shape memory material by controlling the formation of a high-density and evenly distributed R phase.

[0074] like Figure 4As shown, it is a curve of the relative relationship between temperature and strain of the shape memory material processed by an embodiment of the present application after multiple cycles. Among them, the pre-strained material is subjected to high and low temperature (-40 to 100°C) cycles at 200MPa for 20 to 60 times; it can be observed that the wire material has a cyclic strain phenomenon with an amplitude of 1%, confirming that the shape memory alloy material has a two-way memory effect. In addition, after the number of cycles is 1, 5 and 20, the curves of temperature and strain are almost overlapping, indicating that the shape memory material has a high cyclic stability.

[0075] Based on the same inventive concept, please refer to Figure 5 The embodiment of the present application further provides a driving element 100, which is made of the aforementioned shape memory material. The driving element 100 can be in the form of a wire or a sheet, etc. In some embodiments, the driving element 100 is in the form of a wire.

[0076] The driving element 100 made of the aforementioned shape memory material with R-phase change two-way memory effect can achieve two-way memory effect, has low thermal hysteresis, fast response speed, short deformation recovery time, high cycle frequency, and high cycle life and stability.

[0077] Based on the same inventive concept, please refer to Figure 6 , the embodiment of the present application further provides a driving device 200 (or actuator), the driving device 200 includes the aforementioned driving element 100. It is understandable that the driving device 200 may also include a device for inducing the driving element 100 to undergo a phase change, such as a power supply 201, and the driving element 100 undergoes a phase change through the power supply 201 to achieve the purpose of driving. For example, the power supply can heat the driving element to cause a temperature change, thereby causing a phase change. The driving device 200 may be a sensor, an intelligent actuator, etc., but is not limited thereto.

[0078] It can be understood that the driving device may further include a heat source, and the driving element may induce phase change through the heat source.

[0079] The driving element 100 made of the shape memory material with the aforementioned R phase change two-way memory effect does not need to be equipped with a recovery element, which simplifies the structure of the driving device 200, is conducive to the lightweight of the driving device 200, and can also improve the driving frequency, device life and device stability of the driving device 200.

[0080] The embodiments of the present application are further described below through specific examples.

[0081] Example 1

[0082] Step 1, a nickel-titanium shape memory alloy wire, in terms of atomic percentage, includes the following components: nickel: 50.2%; titanium: 49.8%. The shape memory alloy wire is prepared by adding each element component according to the above ratio, smelting and forming. The initial state of the shape memory alloy wire is a cold drawn state.

[0083] Step 2: annealing the shape memory alloy wire in the initial cold-drawn state under vacuum protection at a temperature of 700° C. for 4 hours. After annealing, the average grain size of the R phase of the alloy wire is 25 nm to 50 nm.

[0084] Step 3, subjecting the annealed shape memory alloy wire to low-temperature aging treatment, with the aging temperature being 250° C. and the time being 8 hours.

[0085] Step 4: pre-strain the shape memory alloy wire after low-temperature aging treatment, with the pre-strain amount being 5%, to obtain the shape memory alloy wire.

[0086] The shape memory alloy wire was subjected to a thermally driven cycle test, and the thermally driven cycle frequency was 12.8 Hz.

[0087] Example 2

[0088] Step 1, a nickel-titanium shape memory alloy wire, in terms of atomic percentage, includes the following components: nickel: 51%; titanium: 49%. The shape memory alloy wire is prepared by adding each element component according to the above ratio, smelting and forming. The initial state of the shape memory alloy wire is a cold drawn state.

[0089] Step 2: annealing the shape memory alloy wire in the initial cold-drawn state under vacuum protection at a temperature of 750° C. for 1 hour. After annealing, the R-phase grain size of the alloy wire is 25 nm to 50 nm.

[0090] Step 3, subjecting the annealed shape memory alloy wire to low-temperature aging treatment, with the aging temperature being 280° C. and the time being 5 hours.

[0091] Step 4: pre-strain the shape memory alloy wire after low-temperature aging treatment, with the pre-strain amount being 8%, to obtain the shape memory alloy wire.

[0092] The shape memory alloy wire was subjected to a thermal drive cycle test, and the thermal drive cycle frequency was 10.5 Hz.

[0093] Example 3

[0094] Step 1, a nickel-titanium shape memory alloy wire, in terms of atomic percentage, includes the following components: nickel: 50.8%; titanium: 49.2%. The shape memory alloy wire is prepared by adding each element component according to the above ratio, smelting and forming. The initial state of the shape memory alloy wire is a cold drawn state.

[0095] Step 2: annealing the shape memory alloy wire in the initial cold-drawn state under vacuum protection at a temperature of 650° C. for 8 hours. After annealing, the R-phase grain size of the alloy wire is 25 nm to 50 nm.

[0096] Step 3: subjecting the annealed shape memory alloy wire to low-temperature aging treatment at a temperature of 230° C. for 35 hours.

[0097] Step 4: pre-strain the shape memory alloy wire after low-temperature aging treatment, with the pre-strain amount being 9%, to obtain the shape memory alloy wire.

[0098] The shape memory alloy wire was subjected to a thermally driven cycle test, and the thermally driven cycle frequency was 12.1 Hz.

[0099] Comparative Example 1

[0100] Step 1, a nickel-titanium shape memory alloy wire, in terms of atomic percentage, includes the following components: nickel: 50.2%; titanium: 49.8%. The shape memory alloy wire is prepared by adding each element component according to the above ratio, smelting and forming. The initial state of the shape memory alloy wire is a cold drawn state.

[0101] Step 2: pre-strain the shape memory alloy wire material with a pre-strain amount of 14% to obtain the shape memory alloy wire material.

[0102] The shape memory alloy wire was subjected to a thermal drive cycle test, and the thermal drive cycle frequency was 1.5 Hz.

[0103] By comparing Examples 1-3 with Comparative Example 1, Figures 7 to 10 It can be seen that the cycle frequency of the shape memory alloy wires of Examples 1-3 can reach more than 10 Hz, which is far higher than the traditional B2-B19' two-way effect shape memory alloy wire in Comparative Example 1 (only 1.5 Hz), indicating that the shape memory alloy wires of Examples 1-3 have lower thermal hysteresis and faster response speed; and the shape memory alloy wires of Examples 1-3 have better stability and a cycle life of more than one million times.

[0104] It should be noted that the above are only specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application; the implementation methods of the present application and the features in the implementation methods can be combined with each other without conflict. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A shape memory material, It is characterized in that The shape memory material has a two-way memory effect of R phase transformation. The shape memory material contains an R phase and a B19' martensite lath. A semi-coherent interface exists between the R phase and the B19' martensite lath. An internal stress field exists at the semi-coherent interface. The internal stress field is used to induce a two-way phase transformation of the R phase.

2. The shape memory material according to claim 1, It is characterized in that The cycle frequency of the shape memory material is above 10 Hz.

3. The shape memory material according to claim 1 or 2, It is characterized in that The average grain size of the R phase is 20nm to 100nm.

4. The shape memory material according to any one of claims 1 to 3, It is characterized in that The recoverable strain of the shape memory material is 0.8% to 1.2%.

5. The shape memory material according to any one of claims 1 to 4, It is characterized in that The shape memory material has a use temperature of -40°C to 100°C.

6. A driving element, It is characterized in that The driving element is made of a shape memory material, and the shape memory material is the shape memory material according to any one of claims 1 to 5.

7. A driving device, It is characterized in that Comprising the driving element as claimed in claim 6.

8. The driving device according to claim 7, It is characterized in that The driving device further includes a power source, and the power source is used to induce a phase change in the driving element.

9. A method for processing a shape memory material, It is characterized in that The processing method comprises: Annealing the shape memory material in a cold-drawn state, wherein the annealing temperature is 650-750° C. and the time is less than 5 hours; and The annealed shape memory material is subjected to aging treatment, wherein the temperature of the aging treatment is 230-280° C. and the time is 5-40 hours. The shape memory material after the aging treatment has an R phase change two-way memory effect.

10. The method for processing the shape memory material according to claim 9, It is characterized in that The temperature of the annealing treatment is 680-720°C.

11. A method for processing a shape memory material as claimed in claim 9 or 10, It is characterized in that After the annealing treatment, the average grain size of the R phase is 20 nm to 100 nm.

12. A method for processing a shape memory material according to any one of claims 9 to 11, It is characterized in that After the aging treatment step, the processing method further comprises: The shape memory material after aging treatment is subjected to pre-strain treatment.

13. The method for processing the shape memory material according to claim 12, It is characterized in that After the pre-strain treatment, the strain of the shape memory material is 5% to 9%, and after recovery, the strain of the shape memory material is 0.8% to 1.2%.

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