Method for improving mechanical property of TiNi-based shape memory alloy formed by additive manufacturing through double aftertreatment
By performing double post-treatment of additively manufactured TiNi-based shape memory alloy, including thermal isostatic pressure and high-temperature solution treatment, the problem of poor plasticity is solved, significantly improves the mechanical properties, and provides better functional realization for it in high-temperature applications.
Patent Information
- Application Number
- CN202411457163.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-18
- Publication Date
- 2025-03-04
AI Technical Summary
The poor plasticity of TiNi-based shape memory alloys limits their use in high-temperature applications. How to improve the mechanical properties of additively manufactured TiNi-based shape memory alloys has become a key issue.
The dual post-treatment method is adopted, and the thermal isostatic pressure treatment is first performed, and then the high-temperature solution treatment is performed under high temperature conditions to improve the distribution of the precipitated phase and improve the mechanical properties of the material.
Through dual post-treatment, the tensile strength and tensile strain of the additively manufactured formed TiNi-based shape memory alloy are significantly improved, and its mechanical properties are improved, providing better functional realization for high-temperature applications.
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Abstract
Description
Technical Field
[0001] The invention relates to the technical field of high-temperature shape memory alloy processing and preparation, and in particular to a method for improving the mechanical properties of an additively manufactured TiNi-based shape memory alloy through double post-processing. Background Art
[0002] Ti-Ni shape memory alloy is an intermetallic compound that realizes shape memory effect through solid-state phase transformation. It has good biocompatibility and comprehensive mechanical properties. However, the phase transition temperature of Ti-Ni binary alloy is generally lower than 100°C, which seriously restricts the application field of Ti-Ni shape memory alloy. Ti-Ni based high temperature shape memory alloy has high martensite and austenite phase transition temperature, and can be widely used in the preparation of driving components in aircraft engines, nuclear power plants and other high temperature alarm devices, becoming a hot research direction in the field of shape memory alloys in recent years. Related studies have shown that adding elements such as Hf, Pt and Pb can effectively increase the phase transition temperature of Ti-Ni shape memory alloy. Among them, Ti-Ni-Hf series shape memory alloy has the advantages of relatively low price and excellent performance. It is one of the high temperature shape memory alloys with the most promising engineering applications.
[0003] The plasticity of TiNi-based shape memory alloy after adding Hf element is poor, and the tensile strain is only about 1.5%. Low plasticity seriously limits the application of TiNi-based shape memory alloy. How to improve the mechanical properties of TiNi-based shape memory alloy formed by additive manufacturing 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
[0004] 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 mechanical properties of TiNi-based shape memory alloys formed by additive manufacturing through double post-processing, which can improve the mechanical properties of TiNi-based shape memory alloys formed by additive manufacturing and provide basic mechanical strength and plasticity for improving the functionality of its shape memory effect.
[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:
[0006] A method for improving the mechanical properties of TiNi-based shape memory alloy formed by additive manufacturing through double post-processing, the specific process of the method is:
[0007] (1) Hot isostatic pressing
[0008] The temperature is kept at 1000-1100°C and 100-170MPa for 1-5 hours and then cooled to room temperature to obtain a dense additively manufactured TiNi-based shape memory alloy material.
[0009] (2) High temperature solution treatment
[0010] The material is kept at 1000-1200° C. for 1-5 hours and then air-cooled or water-quenched to room temperature to obtain an additively manufactured TiNi-based shape memory alloy material after high-temperature heat treatment.
[0011] The method for improving the mechanical properties of TiNi-based shape memory alloy formed by additive manufacturing through double post-processing, the TiNi-based shape memory alloy formed by additive manufacturing is a TiNi-based shape memory alloy formed by a metal additive manufacturing method, and the additive manufacturing method includes a forming method of powder laying, powder feeding or wire feeding.
[0012] The method for improving the mechanical properties of the additively manufactured TiNi-based shape memory alloy by double post-treatment, preferably, the additively manufactured TiNi-based shape memory alloy is subjected to hot isostatic pressing treatment under the conditions of 1000-1100°C and 100-170MPa, and then cooled to room temperature with the furnace after keeping warm for 3-5h to obtain a dense additively manufactured TiNi-based shape memory alloy material.
[0013] The method for improving the mechanical properties of the additively manufactured TiNi-based shape memory alloy by double post-treatment is preferably to subject the TiNi-based shape memory alloy after hot isostatic pressing to high-temperature solution treatment, keep it at 1000-1200°C for 2-4 hours, and then cool it to room temperature in air to obtain the additively manufactured TiNi-based shape memory alloy material after high-temperature heat treatment.
[0014] The method for improving the mechanical properties of TiNi-based shape memory alloy formed by additive manufacturing through double post-processing, the composition of the TiNi-based shape memory alloy material is as follows: the Ni content is 49-51at%, and Ti and other elements are the remainder.
[0015] The design concept of the present invention is:
[0016] The present invention performs double post-processing on the additively manufactured TiNi-based shape memory alloy. First, the additively manufactured TiNi-based shape memory alloy is subjected to hot isostatic pressing, the purpose of which is to make up for the forming defects; then, heat treatment is performed under high temperature conditions, and the precipitated phase generated during the forming and hot isostatic pressing process of the additively manufactured TiNi-based shape memory alloy is melted back at high temperature to improve the distribution of the precipitated phase. After the double post-heat treatment, the defects generated during the printing process are significantly reduced, part of the precipitated phase is melted back and the distribution is more uniform, and the mechanical properties are significantly improved.
[0017] The advantages and beneficial effects of the present invention are:
[0018] The method of the present invention improves the mechanical properties of the additively manufactured TiNi-based shape memory alloy through double post-treatment. First, the material is used to manufacture the TiNi-based shape memory alloy; secondly, hot isostatic pressing is carried out under the conditions of 1000-1100°C and 100-170MPa, and the heat preservation is carried out for 1-5 hours and then furnace cooling is carried out to obtain a dense additively manufactured TiNi-based shape memory alloy material; then, the heat preservation is carried out under the conditions of 1000-1200°C for 1-5 hours and then air cooling is carried out to obtain the additively manufactured TiNi-based shape memory alloy material after high-temperature heat treatment. The purpose of hot isostatic pressing treatment is to eliminate the defects generated during the forming process, but due to the characteristics of hot isostatic pressing cooling with the furnace, it experiences multiple temperature intervals during the cooling process, so that more precipitation phases are distributed in the alloy matrix after hot isostatic pressing, and more precipitation phases seriously affect the performance of the alloy. Therefore, it is necessary to heat treat the sample after hot isostatic pressing again. The precipitated phase of the sample after the second high-temperature solution treatment will dissolve back at high temperature, and then quickly cool to room temperature, so that the precipitated phase in the matrix is less, which can effectively improve the mechanical properties of the additively manufactured TiNi-based shape memory alloy. This method can increase the tensile strength from 844MPa to 1051MPa, and the tensile strain from 1.5% to 5.9%, greatly improving the mechanical properties of the additively manufactured TiNi-based shape memory alloy, and providing an enhancement method for the functional realization of the additively manufactured TiNi-based shape memory alloy. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 Stress-strain curves of TiNi-based shape memory alloy formed by additive manufacturing.
[0020] Figure 2 Stress-strain curve of TiNi-based shape memory alloy formed by additive manufacturing after hot isostatic pressing.
[0021] Figure 3 Stress-strain curves of TiNi-based shape memory alloy formed by additive manufacturing after dual post-processing. DETAILED DESCRIPTION
[0022] In the specific implementation process, the present invention proposes a double post-treatment method suitable for additive manufacturing of TiNi-based shape memory alloys as follows: first, the TiNi-based shape memory alloy is formed by additive manufacturing technology; secondly, the TiNi-based shape memory alloy formed by the additive manufacturing technology is subjected to hot isostatic pressing at 1000-1100°C and 100-170MPa, and is kept warm for 3-5 hours and then cooled to room temperature with the furnace to obtain a dense TiNi-based shape memory alloy material; then, the TiNi-based shape memory alloy after the hot isostatic pressing treatment is subjected to secondary post-treatment, and is taken out after being kept warm at 1000-1200°C for 2-4 hours, and is cooled to room temperature in air to obtain an additive manufacturing TiNi-based shape memory alloy material with significantly improved mechanical properties after high-temperature heat treatment.
[0023] The mechanical properties of the additively manufactured TiNi-based shape memory alloy of the present invention are measured according to the requirements of GB / T 228.1-2021 "Tensile test of metallic materials Part 1: Room temperature test method", and the additively manufactured TiNi-based shape memory alloy samples are processed into specimens that meet the test standards and are measured in an environment, equipment and test personnel that meet the test conditions.
[0024] 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.
[0025] Comparative Example 1
[0026] The specific process of this comparative example is: forming a TiNi-based shape memory alloy material by additive manufacturing, and the composition of the TiNi-based shape memory alloy material is as follows: Ti: 30%, Ni: 50%, Hf: 20% (at%).
[0027] like Figure 1 As shown in Figure 1, the stress-strain curve of the original additively manufactured TiNi-based shape memory alloy. Figure 1 It can be seen that the tensile strength of the original sample is 684MPa, and the tensile strain is relatively low, only 1.5%.
[0028] Comparative Example 2
[0029] The specific process of this comparative example is: a TiNi-based shape memory alloy material is formed by additive manufacturing, and the composition of the TiNi-based shape memory alloy material is as follows: Ti: 30%, Ni: 50%, Hf: 20% (at%). The material is kept at 1050°C and 130MPa for 4 hours, and then cooled to room temperature with the furnace.
[0030] like Figure 2As shown in Figure 1, the stress-strain curve of TiNi-based shape memory alloy formed by additive manufacturing after being kept at 1050℃ and 130MPa for 4h. Figure 2 It can be seen that the tensile strength of the additively manufactured TiNi-based shape memory alloy after hot isostatic pressing is 978MPa, and the tensile strain is 3.6%, which is slightly improved compared to the original state.
[0031] Example 1
[0032] The specific process of this embodiment is: forming a TiNi-based shape memory alloy material by an additive manufacturing method, the composition of the TiNi-based shape memory alloy material is as follows: Ti: 30%, Ni: 50%, Hf: 20% (at%). First, the material is kept at 1050°C and 130MPa for 4 hours and then cooled to room temperature with the furnace; then, it is kept at 1050°C for 3 hours and then taken out and cooled to room temperature in the air.
[0033] like Figure 3 As shown in Figure 2, the stress-strain curve of TiNi-based shape memory alloy formed by double post-processing additive manufacturing. Figure 3 It can be seen that the tensile strength of the additively manufactured TiNi-based shape memory alloy after double post-processing is 1154MPa and the tensile strain is 5.9%, which is significantly improved compared with the original state.
[0034] The tensile properties of the additively manufactured TiNi-based shape memory alloy materials obtained after double post-treatment of Comparative Examples 1 to 2 and Example 1 were tested, and the results are shown in Table 1 below.
[0035]
[0036] As can be seen from Table 1, the tensile properties of the double post-processed additively manufactured TiNi-based shape memory alloy obtained by the method of the present invention, especially the comparison of the performance of Example 1 with that of Comparative Example 1, show that the tensile strength after double post-processing is increased by 36.7%, and the tensile strain is increased by 293%, which can significantly solve the problem of poor mechanical properties of the additively manufactured TiNi-based shape memory alloy, and provide an effective solution for the practical application of the material and the realization of functionality.
[0037] The implementation results show that the present invention uses a double post-processing method to bridge the forming defects of the additively manufactured TiNi-based shape memory alloy, reduce the number of harmful precipitated phases, improve their distribution, and improve the mechanical properties of the additively manufactured TiNi-based shape memory alloy.
[0038] 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 mechanical properties of TiNi-based shape memory alloys formed by additive manufacturing through double post-processing, characterized in that: The specific process of this method is: (1) Hot isostatic pressing The temperature is kept at 1000-1100°C and 100-170MPa for 1-5 hours and then cooled to room temperature to obtain a dense additively manufactured TiNi-based shape memory alloy material. (2) High temperature solution treatment The material is kept at 1000-1200° C. for 1-5 hours and then air-cooled or water-quenched to room temperature to obtain an additively manufactured TiNi-based shape memory alloy material after high-temperature heat treatment.
2. The method for improving the mechanical properties of TiNi-based shape memory alloy formed by additive manufacturing through double post-processing according to claim 1, characterized in that: Additive manufacturing forming TiNi based shape memory alloy is a metal additive manufacturing method forming TiNi based shape memory alloy, and the additive manufacturing method includes a forming method of powder laying, powder feeding or wire feeding.
3. The method for improving the mechanical properties of TiNi-based shape memory alloy formed by additive manufacturing through double post-processing according to claim 1, characterized in that: Preferably, the additively manufactured TiNi-based shape memory alloy is subjected to hot isostatic pressing at 1000-1100° C. and 100-170 MPa, kept warm for 3-5 hours, and then furnace-cooled to room temperature to obtain a dense additively manufactured TiNi-based shape memory alloy material.
4. The method for improving the mechanical properties of TiNi-based shape memory alloy formed by additive manufacturing through double post-processing according to claim 3, characterized in that: Preferably, the TiNi-based shape memory alloy after hot isostatic pressing is subjected to high-temperature solution treatment, kept at 1000-1200° C. for 2-4 hours, and then cooled to room temperature in air to obtain an additively manufactured TiNi-based shape memory alloy material after high-temperature heat treatment.
5. The method for improving the mechanical properties of TiNi-based shape memory alloy formed by additive manufacturing through double post-processing according to claim 1, characterized in that: The composition of the TiNi-based shape memory alloy material is as follows: the Ni content is 49-51at%, and Ti and other elements are the balance.