Method for improving superelastic energy of 4D printing TiNi-based shape memory alloy

Abstract

The invention relates to the field of TiNi-based shape memory alloy processing and preparation, in particular to a method for improving the superelasticity of a 4D printing TiNi-based shape memory alloy. The method comprises the steps that firstly, the 4D printing TiNi-based shape memory alloy is subjected to heat preservation for 1-3 h under the condition of 1000-1300 DEG C, then discharged out of a furnace and cooled to the room temperature in air, and the 4D printing TiNi-based shape memory alloy subjected to solution treatment is obtained; and the 4D printing TiNi-based shape memory alloy subjected to solution treatment is subjected to heat preservation for 0.5-200 h under the condition of 200-600 DEG C, then is discharged out of the furnace and is cooled to the room temperature, and the 4D printing TiNi-based shape memory alloy material subjected to solution aging treatment is obtained. According to the 4D printing TiNi-based shape memory alloy, the microstructure of the 4D printing TiNi-based alloy is adjusted through high-temperature solution treatment, so that the microstructure of the TiNi-based shape memory alloy is more uniform, a precipitated phase is promoted to be re-dissolved to form a supersaturated solid solution, then aging treatment is carried out, the precipitated phase is re-precipitated and uniformly distributed in a matrix, and the microstructure of the 4D printing TiNi-based shape memory alloy is obtained. And the hyperelastic performance of the 4D printing TiNi-based shape memory alloy is greatly improved.

Description

Technical field:

[0001] The invention relates to the field of processing and preparation of TiNi-based shape memory alloys, and in particular to a method for improving the superelastic performance of 4D-printed TiNi-based shape memory alloys. Background technology:

[0002] Ti-Ni based shape memory alloy is an intermetallic compound that realizes shape memory effect through solid phase transformation. It has good biocompatibility and comprehensive superelasticity. It is widely used in aerospace, automotive industry, medical, nuclear power and other fields, and has become a hot research direction in the field of smart materials in recent years. TiNi based shape memory alloy prepared by traditional forming method has high hardness and good wear resistance, so it is easy to produce sticking knife and other problems in the subsequent processing process, and the burrs on the processing surface are easy to damage the tool. Forming TiNi based shape memory alloy by 4D printing technology can effectively solve the processing difficulties of TiNi based shape memory alloy, but the superelasticity of 4D printed TiNi based shape memory alloy is poor due to its internal micro defects and uneven organization, which seriously restricts the application of 4D printed TiNi based shape memory alloy. How to improve the superelasticity of 4D printed TiN based shape memory alloy is one of the key issues that need to be solved in the application of this technology in the field of components. Summary of the invention:

[0003] In view of the above-mentioned deficiencies in the prior art, the technical problem to be solved by the present invention is to provide a method for improving the superelastic properties of 4D printed TiNi-based shape memory alloys, which can improve the superelastic properties of 4D printed TiNi-based shape memory alloys.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0005] A method for improving the superelastic performance of 4D printed TiNi-based shape memory alloy, the specific process of the method is:

[0006] (1) High temperature solution treatment

[0007] The 4D printed TiNi-based shape memory alloy material is obtained by heat preservation at 1000-1300°C for 1-3 hours and then air cooling;

[0008] (2) Low temperature aging treatment

[0009] The 4D printed TiNi-based shape memory composite material was obtained by keeping the material at 200-600°C for 0.5-200h and then air cooling to obtain the solid solution aging treatment.

[0010] The method for improving the superelastic performance of 4D printed TiNi-based shape memory alloys, 4D printed TiNi-based shape memory alloys are formed by metal additive manufacturing methods.

[0011] The method for improving the superelastic properties of 4D printed TiNi-based shape memory alloys is preferably characterized in that the high-temperature solution treatment is carried out at 1050 to 1150° C. and then air-cooled for 1 to 3 hours.

[0012] In the method for improving the superelastic properties of 4D printed TiNi-based shape memory alloys, preferably, the TiNi shape memory alloy is subjected to low-temperature aging treatment at 200 to 350° C. for 0.5 to 100 hours and then air-cooled.

[0013] The method for improving the superelastic performance of 4D printed TiNi-based shape memory alloy, in which the atomic percentage of each element is: Ti 49-51at%, and Ni the remainder.

[0014] In the method for improving the superelastic properties of 4D printed TiNi-based shape memory alloys, preferably, the TiNi-based high-temperature shape memory alloy is subjected to low-temperature aging treatment at 450° C. to 600° C. for 1 to 30 hours and then air-cooled.

[0015] The method for improving the superelastic performance of 4D printed TiNi-based shape memory alloys, in which the atomic percentages of the various elements in the TiNi-based high-temperature shape memory alloys are: Ti 25-35%, Ni 49-51%, and Hf 15-25%.

[0016] The method for improving the superelastic properties of 4D printed TiNi-based shape memory alloys, the superelastic properties of 4D printed TiNi-based shape memory alloys are measured according to the requirements of GB / T 228.1-2021 "Metallic Material Tensile Test Part 1: Room Temperature Test Method" or GB / T228.2-2015 "Metallic Material Tensile Test Part 2: High Temperature Test Method", by processing 4D printed TiNi-based shape memory alloy samples into specimens that meet the test standards in an environment, equipment and test personnel that meet the test conditions.

[0017] The design concept of the present invention is:

[0018] The present invention firstly performs a solution heat treatment on the formed sample under high temperature conditions, and the defects generated during the forming of the 4D printed TiNi-based shape memory alloy are bridged by the high temperature solution treatment, and the precipitate phase is dissolved back to form a supersaturated solid solution. After the high temperature solution heat treatment, the defects generated during the printing process are significantly reduced; the 4D printed TiNi-based shape memory alloy after the high temperature treatment is then subjected to low temperature aging treatment to promote the precipitation phase to precipitate uniformly in large quantities, and the superelastic performance is significantly improved. A large amount of Ni-rich supersaturated solid solution can be retained by water quenching at room temperature through high temperature solution treatment. During the low temperature aging process, a large amount of Ni-rich nano-scale precipitation phase will precipitate. The precipitation phase can produce a pinning effect to inhibit dislocation sliding and improve the strength of the alloy matrix. In addition, the fine precipitation phase helps the martensitic phase transformation to occur, limit the plastic deformation of the alloy, and finally improve the superelastic performance of the alloy.

[0019] The advantages and beneficial effects of the present invention are:

[0020] 1. The method of the present invention first uses 4D printing technology to form a TiNi-based shape memory alloy, and then performs high-temperature solid solution treatment on the formed TiNi-based shape memory alloy, keeps it at 1000-1300°C for 1-3h, and then keeps it at 200-550°C for 0.5-200h to obtain a TiNi-based shape memory alloy material after solid solution aging treatment. The present invention performs solid solution aging treatment on the 4D printed TiNi-based shape memory alloy at high temperature and low temperature, respectively, and effectively bridges the metallurgical defects generated during the forming process through solid solution aging treatment, promotes the uniform distribution of precipitation phase, and thus improves the superelastic properties of the 4D printed TiNi-based shape memory alloy.

[0021] 2. The method of the present invention can increase the number of cycles from 10 to 120 times, and reduce the residual strain from 2.0% to below 1.7%, which greatly improves the superelastic properties of 4D printed TiNi-based shape memory alloys and provides an enhancement method for the application of 4D printed TiNi-based shape memory alloys. Description of the drawings:

[0022] Figure 1 The stress-strain curve of 4D printed TiNi-based shape memory alloy after solution treatment at 1050°C and the schematic diagram of the 1st, 10th and 20th cycles. In the figure, the abscissa is strain (%), the ordinate is stress (MPa), and th represents the number of cycles.

[0023] Figure 2 The stress-strain curve of 4D printed TiNi-based shape memory alloy after 1050℃ solution treatment and 300℃ aging treatment and the schematic diagram of the 1st, 50th and 100th cycles. In the figure, the abscissa is strain (%), the ordinate is stress (MPa), and th represents the number of cycles.

[0024] Figure 3 The stress-strain curve of 4D printed TiNiHf high-temperature shape memory alloy after solid solution treatment at 1050℃ and aging treatment at 550℃ and the schematic diagram of the 1st, 10th and 20th cycles. In the figure, the abscissa is strain (%), the ordinate is stress (MPa), and th represents the number of cycles. Specific implementation method:

[0025] In the specific implementation process, the present invention proposes a heat treatment method suitable for 4D printed TiNi-based shape memory alloy. First, the TiNi-based shape memory alloy is formed by 4D printing technology, and then the 4D printed TiNi-based shape memory alloy is kept at 1000-1300°C for 1-3 hours and then taken out of the furnace, and cooled to room temperature in air to obtain a solution-treated 4D printed TiNi-based shape memory alloy. The 4D printed TiNi-based shape memory alloy after the solution treatment is kept at 200-550°C for 0.5-200 hours and then taken out of the furnace and cooled to room temperature to obtain a 4D printed TiNi-based shape memory composite material after solution aging treatment.

[0026] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings, comparative examples and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0027] Comparative Example 1

[0028] The specific process of this comparative example is: forming a TiNi shape memory alloy material by a 4D printing method, the composition of the TiNi shape memory alloy is: Ti 49.2 Ni 50.8 (at.%), the material was kept at 1050 °C for 3 h and then cooled to room temperature in air.

[0029] like Figure 1 As shown in the figure, the stress-strain curve of 4D printed TiNi shape memory alloy after solution treatment at 1050℃. Figure 1 It can be seen that the number of cycles increases after 1050℃ solution treatment, but there is no obvious stress platform.

[0030] Comparative Example 2

[0031] So far, there are no experimental results on superelasticity of 4D printed TiNiHf high-temperature shape memory alloy.

[0032] Example 1

[0033] The specific process of this embodiment is: forming a TiNi shape memory alloy material by a 4D printing method, the composition of the TiNi shape memory alloy is: Ti 49.2 Ni 50.8(at.%); first, the material was kept at 1050°C for 3 hours and then cooled to room temperature in air; then, the solution treated 4D printed TiNi shape memory alloy was kept at 300°C for 24 hours and then cooled to room temperature in air.

[0034] like Figure 2 As shown in Figure 2, the stress-strain curve of 4D printed TiNi shape memory alloy after solution treatment at 1050℃ and aging treatment at 300℃. Figure 2 It can be seen that the superelastic properties of the steel are significantly improved after solution treatment at 1050°C and aging treatment at 300°C.

[0035] Example 2

[0036] The specific process of this embodiment is: forming a TiNiHf high temperature shape memory alloy material by a 4D printing method, the composition of the TiNiHf high temperature shape memory alloy material is: Ti 30 Ni 50 Hf 20 (at.%); first, the material was kept at 1050°C for 3 hours and then cooled to room temperature in air; then, the solution treated 4D printed TiNiHf high temperature shape memory alloy was kept at 550°C for 1 hour and then cooled to room temperature in air.

[0037] like Figure 3 As shown in Figure 2, the stress-strain curve of 4D printed TiNiHf high temperature shape memory alloy after solution treatment at 1050℃ and aging treatment at 550℃. Figure 3 It can be seen that the superelastic properties of the steel are significantly improved after solution treatment at 1050°C and aging treatment at 550°C.

[0038] The superelastic energy of the 4D printed TiNi-based shape memory alloy materials obtained after heat treatment of Comparative Example 1-Comparative Example 2 and Example 1-Example 2 was tested, and the results are shown in Table 1 below.

[0039] Table 1

[0040] sample Cycle times Residual strain Comparative Example 1 20 2.0％ Comparative Example 2 No superelasticity No superelasticity Example 1 100 1.68％ Example 2 20 1.67％

[0041] As can be seen from Table 1, the superelasticity of the 4D printed TiNi-based shape memory alloy after heat treatment obtained by the method of the present invention, after comparing the performance of Example 1 with that of Comparative Example 1, the number of cycles is increased from 10 times to 100 times, and an obvious stress platform residual strain is reduced from 2.0% to 1.68% during the deformation process. After comparing the performance of Example 2 with that of Comparative Example 2, the TiNiHf high-temperature shape memory alloy shows obvious superelasticity. The method of the present invention can significantly solve the problem of poor superelasticity of 4D printed TiNi-based shape memory alloys, and provides an effective solution for the practical application of materials.

[0042] The implementation results show that the present invention adjusts the microstructure of the 4D printed TiNi-based shape memory alloy through high-temperature solid solution treatment, making the microstructure of the TiNi-based shape memory alloy more uniform, prompting the precipitated phase to dissolve back to form a supersaturated solid solution, and then performing aging treatment to make the precipitated phase re-precipitate and evenly distribute in the matrix, thereby greatly improving the superelastic properties of the 4D printed TiNi-based shape memory alloy.

[0043] The above is only the best example of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent change made to the above embodiments according to the technical essence of the invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for improving the superelastic properties of 4D printed TiNi-based shape memory alloys, characterized in that: The specific process of this method is: (1) High temperature solution treatment The 4D printed TiNi-based shape memory alloy material is obtained by heat preservation at 1000-1300°C for 1-3 hours and then air cooling; (2) Low temperature aging treatment The 4D printed TiNi-based shape memory composite material was obtained by keeping the material at 200-600°C for 0.5-200h and then air cooling to obtain the solid solution aging treatment.

2. The method for improving the superelastic properties of 4D printed TiNi-based shape memory alloy according to claim 1, characterized in that: 4D printing of TiNi-based shape memory alloys is a metal additive manufacturing method for forming TiNi-based shape memory alloys.

3. The method for improving the superelastic properties of 4D printed TiNi-based shape memory alloy according to claim 1, characterized in that: Preferably, the high temperature solution treatment is carried out at 1050-1150° C. for 1-3 hours and then air-cooled.

4. The method for improving the superelastic properties of 4D printed TiNi-based shape memory alloy according to claim 1, characterized in that: Preferably, the TiNi shape memory alloy is subjected to low temperature aging treatment at 200 to 350° C. for 0.5 to 100 h and then air-cooled.

5. The method for improving the superelastic properties of 4D printed TiNi-based shape memory alloy according to claim 4, characterized in that: In the TiNi shape memory alloy, the atomic percentage of each element is: Ti 49-51at%, and Ni the rest.

6. The method for improving the superelastic properties of 4D printed TiNi-based shape memory alloy according to claim 1, characterized in that: Preferably, the TiNi-based high temperature shape memory alloy is subjected to low temperature aging treatment by keeping the temperature at 450° C. to 600° C. for 1 to 30 hours and then air cooling.

7. The method for improving the superelastic properties of 4D printed TiNi-based shape memory alloy according to claim 6, characterized in that: In the TiNi-based high-temperature shape memory alloy, the atomic percentage of each element is: Ti 25-35%, Ni 49-51%, and Hf 15-25%.

8. The method for improving the superelastic performance of 4D printed TiNi-based shape memory alloy according to claim 1, characterized in that: The superelastic properties of 4D printed TiNi-based shape memory alloys are measured in an environment, equipment and test personnel that meet the test conditions according to the requirements of GB / T 228.1-2021 "Tensile test of metallic materials Part 1: Room temperature test method" or GB / T 228.2-2015 "Tensile test of metallic materials Part 2: High temperature test method".

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