Ti-Fe-Ni-Zr shape memory alloy and preparation method thereof

Abstract

The invention discloses a Ti-Fe-Ni-Zr shape memory alloy. The Ti-Fe-Ni-Zr shape memory alloy is prepared from the following components in atomic percent: 46.5 to 48 at% of Ti, 2.0 to 3.5 at% of Fe, 30 at% of Ni and 20 at% of Zr. The invention also discloses a preparation method of the shape memory alloy, which comprises the following steps: weighing the raw materials according to the percentage, smelting in a smelting furnace for multiple times to obtain an alloy ingot, and cooling to obtain the Ti-Fe-Ni-Zr shape memory alloy. Due to the influence of Fe and Zr elements in the shape memory alloy on alloying of the Ti-Ni alloy, the alloy has the condition that a B19'phase and a B2 phase coexist, and the alloy has the performance characteristics of wide temperature range, large temperature change and high hardness.

Description

Technical Field

[0001] The present invention belongs to the technical field of shape memory alloys and their preparation methods, and relates to a Ti-Fe-Ni-Zr shape memory alloy. The present invention also relates to a preparation method of the above shape memory alloy. Background Art

[0002] Shape Memory Alloys (SMA) are intelligent materials with Shape Memory Effect (SME) and Superelasticity (SE). Their main feature is that after applying a large deformation to the material and then heating it to a certain temperature, the material can almost completely return to its original shape. Shape memory alloys can undergo forward and reverse stress-induced martensitic phase transformations through the loading and unloading of uniaxial stress. Since latent heat of phase transformation is generated during the phase transformation process, the alloy releases heat during the forward phase transformation and cools during the reverse phase transformation during the stress cycle. Shape memory alloys have a large latent heat of phase transformation and phase transformation strain, so they have a relatively large adiabatic temperature change. Therefore, shape memory alloys have excellent elastocaloric properties, and thus the elastocaloric effect of shape memory alloys can be applied to heat transfer and refrigeration. This property is widely used in the field of elastocaloric refrigeration.

[0003] However, this drastic first-order martensitic phase transformation usually occurs only in a very narrow temperature range, which greatly limits the application scenarios and temperature range of shape memory alloys. Moreover, high elastocaloric effects mainly appear in alloys in the form of wires, thin films, etc. However, as non-bulk materials, the application scope of wire and thin film materials is limited. Currently, the working temperature range of the elastocaloric effect of shape memory alloys is relatively narrow, and the isothermal entropy change of martensitic phase transformation does not meet the industrial refrigeration requirements. Most shape memory alloy systems are difficult to achieve the coordinated optimization of the working temperature range and isothermal entropy change. Research shows that the first-order martensitic phase transformation can be regulated by changing its microstructure, composition regulation, and other means, so as to broaden the martensitic phase transformation temperature range. However, this has also led to the suppression of the martensitic phase transformation and the weakening of the refrigeration capacity, and no new shape memory alloy with both large temperature change and wide temperature window characteristics has been obtained. Summary of the Invention

[0004] The purpose of the present invention is to provide a Ti-Fe-Ni-Zr shape memory alloy, which has the characteristics of a wide temperature range, large temperature change, and high hardness.

[0005] Another purpose of the present invention is to provide a preparation method of the above Ti-Fe-Ni-Zr shape memory alloy.

[0006] The technical solution adopted by the present invention is that the Ti-Fe-Ni-Zr shape memory alloy is composed of the following components according to atomic percentage: 46.5~48 at% Ti, 2.0~3.5 at% Fe, 30 at% Ni, 20 at% Zr.

[0007] The features of the present invention also lie in: The Ti-Fe-Ni-Zr shape memory alloy consists of the following components according to atomic percentages: 46.5 at% Ti, 3.5 at% Fe, 30 at% Ni, 20 at% Zr.

[0008] Another technical solution adopted by the present invention is the preparation method of the Ti-Fe-Ni-Zr shape memory alloy, which is specifically implemented according to the following steps: Step 1: Weigh the raw materials of Ti, Ni, Fe, and Zr according to atomic percentages. The percentages of each raw material are: 46.5~48 at% Ti, 2.0~3.5 at% Fe, 30 at% Ni, 20 at% Zr. Put the above raw materials into the melting furnace. Step 2: Arc ignition is carried out in a vacuum argon environment. After the arc is stable, set the arc current, and an alloy ingot is obtained through melting. Step 3: Turn off the arc gun, turn the ingot over, and repeat Step 2 multiple times. Step 4: After the sample obtained in Step 3 is cooled, the Ti-Fe-Ni-Zr shape memory alloy is obtained.

[0009] The features of another technical solution of the present invention also lie in: In Step 1, the percentages of each raw material are: 46.5 at% Ti, 3.5 at% Fe, 30 at% Ni, 20 at% Zr.

[0010] In Step 1, the raw materials of Ti and Zr elements are short rod-shaped particles, the raw material of Ni element is cylindrical particles, and the raw material of Fe element is irregularly shaped particles.

[0011] In Step 2, the pressure in the melting furnace is lower than 0.05 MPa.

[0012] In Step 2, when arc ignition is carried out, the distance between the arc gun and the melting sample is 2 - 3 mm.

[0013] During the melting process of Step 2, the arc current is 350~450 A, and an 8 A magnetic stirring current is added.

[0014] During the melting process of Step 2, after starting melting, first keep the raw materials in a molten state for 90 s, and then adjust the position of the arc gun to a distance of 20~30 mm from the sample to obtain an ingot through melting.

[0015] In Step 3, repeat Step 2 for 5 - 7 times.

[0016] The beneficial effects of the present invention are: The Ti-Fe-Ni-Zr shape memory alloy of the present invention incorporates Fe element and Zr element on the basis of Ti-Ni, and optimizes the percentages of the four elements. Due to the influence of Fe and Zr elements on the alloying of Ti-Ni alloy, the above alloy exhibits the coexistence of B19' phase and B2 phase, making the alloy show the performance characteristics of wide temperature range, large temperature change and high hardness. In addition, the preparation method of the Ti-Fe-Ni-Zr shape memory alloy of the present invention is simple and has low cost. Brief Description of the Drawings

[0017] Figure 1 It is the DSC curve graph of the alloys prepared in Examples 1-4 and Comparative Examples 1-4 of the present invention; Figure 2 It is the DMA test curve graph of the alloys prepared in Examples 1-4 and Comparative Examples 1-4 of the present invention; Figure 3 It is the test result graph of the compression test of the alloys prepared in Examples 1-4 and Comparative Examples 1-4 of the present invention; Figure 4 It is the phase transformation induced stress and isothermal entropy change graph of the alloys prepared in Examples 1-4 and Comparative Examples 1-4 of the present invention; Figure 5 It is the temperature range isothermal entropy change graph of the alloys prepared in Examples 1-4 and Comparative Examples 1-4 of the present invention; Figure 6 It is the temperature-strain curve graph of the alloys prepared in Examples 1-4 and Comparative Examples 1-4 of the present invention. Detailed Description of the Invention

[0018] The present invention will be described in detail below with reference to the drawings and specific embodiments.

[0019] The Ti-Fe-Ni-Zr shape memory alloy of the present invention has the chemical formula Ti 50-x Fe x Ni 30 Zr 20 , where x = 2.0 - 3.5, and is composed of the following components in atomic percentage: 46.5 - 48 at% Ti, 2.0 - 3.5 at% Fe, 30 at% Ni, 20 at% Zr.

[0020] The preparation method of the Ti-Fe-Ni-Zr shape memory alloy of the present invention is specifically implemented according to the following steps: Step 1, according to Ti 50-x Fe x Ni 30 Zr 20Weigh the raw materials Ti, Ni, Fe, and Zr according to the atomic ratio, where x = 2.0 - 3.5, and put the above raw materials into a melting furnace. Among them, the raw materials of Ti and Zr elements are small short rod-shaped particles, the raw material of Ni element is a cylindrical small particle, and the raw material of Fe element is a small particle with an irregular shape. Step 2: In an argon environment of 0.05 MPa, adjust the melting sample to the bottom of the arc gun, adjust the distance between the arc gun and the melting sample within the range of 2 - 3 mm, strike an arc. After the arc is stable, adjust the arc current to 350 - 450 A, and add an 8 A magnetic stirring current to start melting. First, keep the raw materials in a molten state for 90 s, and then adjust the distance between the arc gun and the melting sample to within the range of 20 - 30 mm to obtain an ingot. Step 3: Turn off the arc gun, use a mechanical rod to turn over the ingot in the melting furnace, and repeat Step 2 five to seven times. Step 4: Turn off the arc gun, turn off the power supply of the melting furnace, and after the sample obtained in Step 3 cools down, obtain a Ti-Fe-Ni-Zr shape memory alloy.

[0021] Example 1: In the shape memory alloy prepared in this example, x = 2.0, that is, Ni 48 Fe 2 Ti 30 Zr 20 Shape memory alloy: Step 1: Weigh the raw materials Ti, Ni, Fe, and Zr according to the atomic ratio of Ni 48 Fe 2 Ti 30 Zr 20 and put the above raw materials into a melting furnace. Step 2: In an argon environment of 0.05 MPa, adjust the melting sample to the bottom of the arc gun, adjust the arc gun so that its distance from the melting sample is 3 mm, strike an arc. After the arc is stable, adjust the arc current to 400 A, and add an 8 A magnetic stirring current to start melting. First, keep the raw materials in a molten state for 90 s, and then adjust the position of the arc gun so that its distance from the melting sample is 20 mm to obtain an ingot. Step 3: Turn off the arc gun, use a mechanical rod to turn over the ingot in the melting furnace, and repeat Step 2 five times. Step 4: Turn off the arc gun, turn off the power supply of the melting furnace, and after the sample obtained in Step 3 cools down, obtain Ni 48 Fe 2 Ti 30 Zr 20 Shape memory alloy.

[0022] Example 2: In the shape memory alloy prepared in this example, x = 2.5, that is, Ni 47.5 Fe2.5 Ti 30 Zr 20 Shape memory alloy: Step 1: Weigh the raw materials Ti, Ni, Fe, and Zr according to the atomic ratio of 47.5 Fe 2.5 Ti 30 Zr 20 Put the above raw materials into the melting furnace; Step 2: In an argon environment of 0.05 MPa, adjust the melting sample to the bottom of the arc gun, adjust the arc gun so that its distance from the melting sample is 2.8 mm, strike an arc. After the arc is stable, adjust the arc current to 420 A, and add an 8 A magnetic stirring current to start melting. First, keep the raw materials in a molten state for 90 s, and then adjust the position of the arc gun so that its distance from the melting sample is 25 mm to obtain an ingot; Step 3: Turn off the arc gun, use a mechanical rod to turn the ingot over in the melting furnace, and repeat Step 2 six times; Step 4: Turn off the arc gun, turn off the power supply of the melting furnace. After the sample obtained in Step 3 is cooled, obtain the Ni 47.5 Fe 2.5 Ti 30 Zr 20 shape memory alloy.

[0023] Example 3: In the shape memory alloy prepared in this example, x = 3.0, that is, Ni 47 Fe 3 Ti 30 Zr 20 Shape memory alloy: Step 1: Weigh the raw materials Ti, Ni, Fe, and Zr according to the atomic ratio of 47 Fe 3 Ti 30 Zr 20 Put the above raw materials into the melting furnace; Step 2: In an argon environment of 0.05 MPa, adjust the melting sample to the bottom of the arc gun, adjust the arc gun so that its distance from the melting sample is 3 mm, strike an arc. After the arc is stable, adjust the arc current to 430 A, and add an 8 A magnetic stirring current to start melting. First, keep the raw materials in a molten state for 90 s, and then adjust the position of the arc gun so that its distance from the melting sample is 25 mm to obtain an ingot; Step 3: Turn off the arc gun, use a mechanical rod to turn the ingot over in the melting furnace, and repeat Step 2 seven times; Step 4: Turn off the arc gun, turn off the power supply of the melting furnace. After the sample obtained in Step 3 is cooled, obtain the Ni 47 Fe 3 Ti 30 Zr20 Shape memory alloy

[0024] Example 4 In the shape memory alloy prepared in this example, x = 3.5, that is, Ni 46.5 Fe 3.5 Ti 30 Zr 20 Shape memory alloy Step 1: Weigh the raw materials Ti, Ni, Fe, and Zr according to the atomic ratio of Ni 46.5 Fe 3.5 Ti 30 Zr 20 Put the above raw materials into the melting furnace Step 2: In an argon environment of 0.05 MPa, adjust the melting sample to the bottom of the arc gun, adjust the arc gun so that its distance from the melting sample is 3 mm, strike an arc. After the arc is stable, adjust the arc current to 450 A, and add an 8 A magnetic stirring current. Start melting. First, keep the raw materials in a molten state for 90 s, then adjust the position of the arc gun so that its distance from the melting sample is 30 mm, and melt to obtain an ingot Step 3: Turn off the arc gun, use a mechanical rod to turn the ingot over in the melting furnace, and repeat Step 2 six times Step 4: Turn off the arc gun, turn off the power supply of the melting furnace. After the sample obtained in Step 3 cools down, obtain Ni 46.5 Fe 3.5 Ti 30 Zr 20 Shape memory alloy

[0025] Example 5 In the shape memory alloy prepared in this example, x = 3.5, that is, Ni 46.5 Fe 3.5 Ti 30 Zr 20 Shape memory alloy Step 1: Weigh the raw materials Ti, Ni, Fe, and Zr according to the atomic ratio of Ni 46.5 Fe 3.5 Ti 30 Zr 20 Put the above raw materials into the melting furnace Step 2: In an argon environment of 0.05 MPa, adjust the melting sample to the bottom of the arc gun, adjust the arc gun so that its distance from the melting sample is 2 mm, strike an arc. After the arc is stable, adjust the arc current to 350 A, and add an 8 A magnetic stirring current. Start melting. First, keep the raw materials in a molten state for 90 s, then adjust the position of the arc gun so that its distance from the melting sample is 25 mm, and melt to obtain an ingot Step 3: Turn off the arc gun, use a mechanical rod to turn the ingot over in the melting furnace, and repeat Step 2 six times Step 4: Turn off the arc gun and the power supply of the melting furnace. After the sample obtained in Step 3 has cooled down, Ni is obtained. 46.5 Fe 3.5 Ti 30 Zr 20 shape memory alloy.

[0026] Example 6: In the shape memory alloy prepared in this example, x = 3.5, that is, Ni 46.5 Fe 3.5 Ti 30 Zr 20 shape memory alloy: Step 1: Weigh the raw materials Ti, Ni, Fe, and Zr according to the atomic ratio of Ni 46.5 Fe 3.5 Ti 30 Zr 20 Put the above raw materials into the melting furnace; Step 2: Under an argon atmosphere of 0.05 MPa, adjust the melted sample to the bottom of the arc gun, adjust the arc gun so that its distance from the melted sample is 2.5 mm, strike an arc. After the arc is stable, adjust the arc current to 380 A and add an 8 A magnetic stirring current to start melting. First, keep the raw materials in a molten state for 90 s, then adjust the position of the arc gun so that its distance from the melted sample is 25 mm to obtain an ingot; Step 3: Turn off the arc gun, use a mechanical rod to turn the ingot over in the melting furnace, and repeat Step 2 seven times; Step 4: Turn off the arc gun and the power supply of the melting furnace. After the sample obtained in Step 3 has cooled down, Ni 46.5 Fe 3.5 Ti 30 Zr 20 shape memory alloy.

[0027] Comparative Example 1: In the shape memory alloy prepared in this comparative example, x = 0, that is, Ti 50 Ni 30 Zr 20 shape memory alloy, and Fe is not added to the alloy: Step 1: Weigh the raw materials Ti, Ni, and Zr according to the atomic ratio of Ti 50 Ni 30 Zr 20 Put the above raw materials into the melting furnace; Step 2: Under an argon environment of 0.05 MPa, adjust the smelting sample to the bottom of the arc gun, adjust the arc gun so that its distance from the smelting sample is 2.8 mm, strike an arc. After the arc is stable, adjust the arc current to 420 A, and add an 8 A magnetic stirring current. Start smelting. First, keep the raw materials in a molten state for 90 s, then adjust the position of the arc gun so that its distance from the smelting sample is 25 mm, and smelt to obtain an ingot; Step 3: Turn off the arc gun, use a mechanical rod to turn over the ingot in the smelting furnace, and repeat Step 2 six times; Step 4: Turn off the arc gun, turn off the power supply of the smelting furnace. After the sample obtained in Step 3 is cooled, Ti 50 Ni 30 Zr 20 shape memory alloy is obtained.

[0028] Comparative Example 2: In the shape memory alloy prepared in this comparative example, x = 0.5, that is, Ni 49.5 Fe 0.5 Ti 30 Zr 20 shape memory alloy: Step 1: Weigh the raw materials Ti, Ni, Fe, and Zr according to the atomic ratio of Ni 49.5 Fe 0.5 Ti 30 Zr 20 and put the above raw materials into the smelting furnace; Step 2: Under an argon environment of 0.05 MPa, adjust the smelting sample to the bottom of the arc gun, adjust the arc gun so that its distance from the smelting sample is 2.8 mm, strike an arc. After the arc is stable, adjust the arc current to 420 A, and add an 8 A magnetic stirring current. Start smelting. First, keep the raw materials in a molten state for 90 s, then adjust the position of the arc gun so that its distance from the smelting sample is 25 mm, and smelt to obtain an ingot; Step 3: Turn off the arc gun, use a mechanical rod to turn over the ingot in the smelting furnace, and repeat Step 2 six times; Step 4: Turn off the arc gun, turn off the power supply of the smelting furnace. After the sample obtained in Step 3 is cooled, Ni 49.5 Fe 0.5 Ti 30 Zr 20 shape memory alloy is obtained.

[0029] Comparative Example 3: In the shape memory alloy prepared in this comparative example, x = 1.0, that is, Ni 49 Fe 1 Ti 30 Zr 20 shape memory alloy: Step 1: Weigh the raw materials according to the atomic ratio of Ni 49 Fe1 Ti 30 Zr 20 Weigh the raw materials Ti, Ni, Fe, and Zr according to the atomic ratio, and put the above raw materials into the melting furnace; Step 2: Under an argon atmosphere of 0.05 MPa, adjust the melting sample to the bottom of the arc gun, adjust the arc gun to a distance of 2.8 mm from the melting sample, strike an arc. After the arc is stable, adjust the arc current to 420 A, and add an 8 A magnetic stirring current. Start melting. First, keep the raw materials in a molten state for 90 s, then adjust the position of the arc gun to a distance of 25 mm from the melting sample to obtain an ingot; Step 3: Turn off the arc gun, turn over the ingot in the melting furnace with a mechanical rod, and repeat Step 2 six times; Step 4: Turn off the arc gun, turn off the power supply of the melting furnace. After the sample obtained in Step 3 is cooled, obtain a Ni 49 Fe 1 Ti 30 Zr 20 shape memory alloy.

[0030] Comparative Example 4: In the shape memory alloy prepared in this comparative example, x = 1.5, that is, Ni 48.5 Fe 1.5 Ti 30 Zr 20 shape memory alloy: Step 1: Weigh the raw materials Ti, Ni, Fe, and Zr according to the atomic ratio of Ni 48.5 Fe 1.5 Ti 30 Zr 20 and put the above raw materials into the melting furnace; Step 2: Under an argon atmosphere of 0.05 MPa, adjust the melting sample to the bottom of the arc gun, adjust the arc gun to a distance of 2.8 mm from the melting sample, strike an arc. After the arc is stable, adjust the arc current to 420 A, and add an 8 A magnetic stirring current. Start melting. First, keep the raw materials in a molten state for 90 s, then adjust the position of the arc gun to a distance of 25 mm from the melting sample to obtain an ingot; Step 3: Turn off the arc gun, turn over the ingot in the melting furnace with a mechanical rod, and repeat Step 2 six times; Step 4: Turn off the arc gun, turn off the power supply of the melting furnace. After the sample obtained in Step 3 is cooled, obtain a Ni 48.5 Fe 1.5 Ti 30 Zr 20 shape memory alloy.

[0031] Cut the 8 shape memory alloys obtained in Examples 1-4 and Comparative Examples 1-4 into 2×2×1 mm 3The thin slices were solution-treated in a vacuum quartz tube at 1273K for 1h, followed by water quenching, mechanically polished with sandpaper, and then the following tests were carried out on the obtained 8 shape memory alloys: DSC tests were carried out with a heating / cooling rate of 10K / min, and the results are shown in Figure 1 . The phase transformation temperature Ms and phase transformation enthalpy of the TiNiFeZr system alloys were statistically analyzed, and the results are shown in Table 1. From Figure 1 and Table 1, it can be seen that relatively obvious peaks appeared on the heat flow curves, and they gradually widened with the increase of Fe, and the phase transformation temperature also decreased. When the Fe content was 0 - 1.5% (Comparative Examples 1 - 4), the phase transformation temperature was relatively high; when the Fe content was 2.0 - 3.5% (Examples 1 - 4), the phase transformation temperature was low. Among them, for the Ni 46.5 Fe 3.5 Ti 30 Zr 20 prepared in Example 4, almost no phase transformation peak could be observed on the DSC curve, the phase transformation temperature of the alloy was -25°C, and the phase transformation enthalpy decreased to 1.249 J·g -1 , and the temperature range of martensitic transformation has been widened from 31°C to 93°C. The first-order martensitic transformation of the alloy sample was almost completely suppressed, and the temperature range of martensitic transformation was widened.

[0032] Table 1 Statistical table of phase transformation temperature and phase transformation enthalpy of TiNiFeZr system alloys

[0033] DMA tests were carried out in the single cantilever beam mode. The six selected test frequencies were 0.2Hz, 0.4Hz, 1.0Hz, 4Hz, 10Hz, and 20Hz, and the heating and cooling rates were 2K / min. The results are as Figure 2 shown. In each small figure, the upper part represents the change in internal friction, and the lower part represents the change in storage modulus. It can be seen that when the Fe content was 0 - 1.5% (Comparative Examples 1 - 4), valleys of storage modulus and peaks of internal friction appeared at relatively high temperatures; when the Fe content was 2.0 - 3.5% (Examples 1 - 4), the temperatures at which valleys of storage modulus and peaks of internal friction appeared were lower. As the Fe content gradually increased, the curve of storage modulus began to become smooth, indicating that the addition of Fe element led to the suppression of the first-order martensitic transformation of Ti 50-x Fe x Ni 30 Zr 20 alloys, gradually transitioning to second-order martensitic transformation, and the effect of smooth storage modulus curve was only achieved when the Fe content was 2.0 - 3.5%.

[0034] Compression test was carried out, and the results are shown in Figure 3The phase transformation induced stress and isothermal entropy change of the alloy were calculated by the double tangent method and the Clausius-Clapeyron equation respectively. The results are shown in Figure 4 As can be seen from the figure, the Fe0 alloy sample prepared in Comparative Example 1 exhibited superelasticity, but its level of the third isothermal entropy change was not high. The Fe0.5 and Fe1.0 samples prepared in Comparative Examples 2 and 3 had non-zero isothermal entropy change only in the second compression test (160 °C). The Fe1.5 alloy sample prepared in Comparative Example 4 did not show superelasticity in all compression tests, and its isothermal entropy change was 0, indicating that it did not have the elastocaloric effect. The Fe2.0 alloy sample prepared in Example 1 showed superelasticity again in the second compression test (40 °C), and the isothermal entropy change was non-zero. When the doping content of Fe element reached 2.5 atomic percentage (Example 2), superelastic characteristics were shown in both the second (60 °C) and the third compression tests (40 °C), and its isothermal entropy change was the highest, with the best elastocaloric performance. When the doping content of Fe element reached 3.0 and 3.5 (Examples 3 and 4), superelasticity appeared only in the second compression experiment.

[0035] The temperature-domain isothermal entropy change diagram of the TiNiFeZr alloy was plotted, as shown in Figure 5 As can be seen from the figure, for the alloy sample with 0 Fe element content, its temperature domain was the largest, up to 60 °C. However, its elastocaloric performance was not very good. The maximum value of the isothermal entropy change was taken in the figure. Although the Fe0 sample showed the elastocaloric effect in all three compression tests, in the latter two compression tests, the elastocaloric effect was so small that it could be ignored, and its actual temperature domain should be less than 60 °C. For the Fe2.5 sample in the two compression tests, the values of its isothermal entropy change were both as high as 1.342 J•(kg•K) -1 Moreover, the temperature domain span also reached 40 °C, making it the alloy sample with the best comprehensive elastocaloric performance in the TiNiFeZr-based alloys.

[0036] Using the three-point bending mode of DMA, the temperature-strain curves of the alloy were tested under different bending stresses, as shown in Figure 6 As can be seen from the figure, alloys with Fe content of 0 - 1.5% showed residual strain under a constant force of 300 - 400 MPa, while alloys with Fe content of 2 - 3.5% showed residual strain under a constant force above 400 MPa. Among them, the Fe 3.5 alloy prepared in Example 4 did not show residual strain until the stress was loaded to 500 MPa, and had the best shape memory effect.

Claims

1. Ti-Fe-Ni-Zr shape memory alloy, characterized in that: The components are as follows in atomic percentage: 46.5~48at%Ti, 2.0~3.5at%Fe, 30at%Ni, 20at%Zr.

2. The Ti-Fe-Ni-Zr shape memory alloy according to claim 1, characterized in that: The components are as follows in atomic percentage: 46.5at%Ti, 3.5at%Fe, 30at%Ni, 20at%Zr.

3. A method for preparing a Ti-Fe-Ni-Zr shape memory alloy, characterized in that: Follow the steps below to implement it: Step 1, weigh Ti, Ni, Fe, and Zr raw materials according to atomic percentage, the percentage of each raw material is: 46.5-48at%Ti, 2.0-3.5at%Fe, 30at%Ni, 20at%Zr, and put the above raw materials into a smelting furnace; Step 2, striking an arc in a vacuum argon environment, setting the arc current after the arc is stable, and obtaining an alloy ingot through smelting; Step 3, turn off the arc gun, turn the ingot over, and repeat step 2 several times; Step 4: After the sample obtained in step 3 is cooled, a Ti-Fe-Ni-Zr shape memory alloy is obtained.

4. The method for preparing the Ti-Fe-Ni-Zr shape memory alloy according to claim 3, characterized in that: In step 1, the percentage of each raw material is: 46.5at%Ti, 3.5at%Fe, 30at%Ni, 20at%Zr.

5. The method for preparing the Ti-Fe-Ni-Zr shape memory alloy according to claim 3, characterized in that: In step 1, the raw materials of Ti and Zr elements are short rod-shaped particles, the raw material of Ni element is cylindrical particles, and the raw material of Fe element is irregularly shaped particles.

6. The method for preparing the Ti-Fe-Ni-Zr shape memory alloy according to claim 3, characterized in that: In step 2, the pressure in the smelting furnace is lower than 0.05 MPa.

7. The method for preparing the Ti-Fe-Ni-Zr shape memory alloy according to claim 3, characterized in that: In step 2, when striking the arc, the arc gun is 2-3 mm away from the smelting sample.

8. The method for preparing the Ti-Fe-Ni-Zr shape memory alloy according to claim 3, characterized in that: During the melting process of step 2, the arc current is 350~450A, and 8A magnetic stirring current is added.

9. The method for preparing the Ti-Fe-Ni-Zr shape memory alloy according to claim 3, characterized in that: During the smelting process of step 2, after the smelting starts, the raw material is kept in a molten state for 90 seconds, and then the position of the arc gun is adjusted to be 20 to 30 mm away from the sample, and the ingot is obtained by smelting.

10. The method for preparing the Ti-Fe-Ni-Zr shape memory alloy according to claim 3, characterized in that: In step 3, repeat step 2 5-7 times.

Images