Shape memory alloy and preparation method and application thereof
By adding Sn elements to NiTiHf alloy and forming eutectic structures with a layered structure, the problem of plastic slipping easily during deformation of NiTiHf high-temperature shape memory alloy is solved, and good high-temperature shape memory effect and super elastic performance are achieved. .
Patent Information
- Application Number
- CN202411017574.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-29
- Publication Date
- 2025-02-18
AI Technical Summary
NiTiHf high-temperature shape memory alloys are prone to plastic slip during deformation, resulting in superelastic recovery strain and high-temperature shape memory strain that are difficult to meet the requirements of engineering applications.
By adding Sn elements to the NiTiHf alloy, the B19’-NiTiHf matrix phase and the Ti3Sn phase were formed, and the vacuum arc melting furnace was used to repeatedly melt to form a eutectic structure in a sheet-like structure.
The high-temperature shape memory effect and superelastic properties of the alloy are improved, so that it can serve in environments above 100℃, and can even reach 250℃.
Smart Images
Figure CN119464889A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the field of alloys, and in particular to a shape memory alloy and a preparation method and application thereof. Background Art
[0002] Shape memory alloys are functional metal materials with superelasticity and shape memory effects. Currently, the most widely used shape memory alloy is NiTi, but its martensitic phase transition temperature is not higher than 100°C, and it cannot serve in environments above 100°C, such as weapons and equipment, aerospace vehicles, nuclear reactors and other temperature-driven devices. At present, the martensitic phase transition temperature of shape memory alloys can be increased by adding elements such as Pd, Pt, Au to replace part of the Ni element or adding elements such as Zr and Hf to replace part of the Ti element in NiTi binary alloys. Among them, NiTiHf high-temperature shape memory alloy has the advantages of relatively low price and high phase transition temperature. As a high-temperature shape memory alloy, it has broad application prospects.
[0003] However, the dislocation slip critical stress of NiTiHf high temperature shape memory alloy is low, and the martensitic detwinning stress and martensitic phase transformation critical stress are both higher than the dislocation slip critical stress, which makes NiTiHf high temperature shape memory alloy prone to plastic slip during deformation, thereby deteriorating its superelastic recovery strain and high temperature shape memory strain. At present, the high temperature shape memory effect and superelastic performance of NiTiHf alloy still cannot meet the requirements of engineering applications. Summary of the invention
[0004] The invention provides a shape memory alloy having good high-temperature shape memory effect and superelastic performance.
[0005] The invention also provides a preparation method and application of the shape memory alloy.
[0006] A first aspect of the present invention provides a shape memory alloy, comprising a eutectic structure;
[0007] The eutectic structure includes a B19'-NiTiHf matrix phase and a Ti3Sn phase;
[0008] The B19'-NiTiHf matrix phase and the Ti3Sn phase are alternately arranged in a lamellar structure.
[0009] The alloy as described above, further comprising a (Ti,Hf)2Ni phase.
[0010] In the alloy as described above, the volume proportion of the B19'-NiTiHf matrix phase is 52% to 75%, the volume proportion of the Ti3Sn phase is 22% to 40%, and the volume proportion of the (Ti, Hf)2Ni phase is 3% to 8%.
[0011] The alloy as described above, wherein the chemical formula of the alloy is (Ni 50 Ti 35 Hf 15 ) 100-4x (Ti 75 Sn 25 ) 4x , where 6≤x≤10.
[0012] A second aspect of the present invention provides a method for preparing the above alloy, which comprises the following steps:
[0013] The Ni metal, Ti metal, Hf metal and Sn metal are uniformly mixed, smelted at a temperature not lower than 2227°C, and after the metal components in the molten solution are uniform, cooled to room temperature to obtain an ingot;
[0014] The ingot is kept at 850-1000° C. for 0.5-4 hours and then cooled to room temperature.
[0015] In the preparation method as described above, a vacuum arc melting furnace is used for the melting process.
[0016] In the preparation method as described above, the current of the vacuum arc melting furnace is 200-400A, and the melting time is 60-120S.
[0017] The preparation method as described above, wherein the vacuum arc melting furnace is used for repeated melting 4 to 8 times.
[0018] In the preparation method as described above, the cooling method is one of furnace cooling, water cooling and air cooling.
[0019] The present invention provides a temperature driving device, which comprises the above alloy or the alloy prepared according to the above preparation method.
[0020] The shape memory alloy of the invention is prepared by adding Sn element into NiTiHf alloy to obtain NiTiHfSn alloy, which has good high-temperature shape memory effect and superelastic performance. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.
[0022] Figure 1 is an XRD diagram of an alloy in one embodiment of the present invention;
[0023] Figure 2 This is a SEM image of an alloy in an embodiment of the present invention, obtained by observing under a scanning electron microscope with a magnification of 2000 times. DETAILED DESCRIPTION
[0024] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0025] A first aspect of the present invention provides a shape memory alloy, comprising a eutectic structure;
[0026] The eutectic structure includes a B19'-NiTiHf matrix phase and a Ti3Sn phase;
[0027] The B19'-NiTiHf matrix phase and the Ti3Sn phase are alternately arranged in a lamellar structure.
[0028] The NiTiHfSn shape memory alloy of the present invention forms a B19'-NiTiHf matrix phase and a Ti3Sn phase after adding Sn element to the NiTiHf alloy. The inventor speculates that it may be because the B19'-NiTiHf matrix phase and the Ti3Sn phase can constitute a eutectic structure, and the B19'-NiTiHf matrix phase and the Ti3Sn phase are alternately arranged in a lamellar structure, so that the interface between the Ti3Sn phase and the eutectic phase can strengthen the B19'-NiTiHf matrix phase, thereby having good high-temperature shape memory effect and superelastic performance.
[0029] In a specific embodiment, a (Ti,Hf)2Ni phase is also included.
[0030] The presence of (Ti,Hf)2Ni phase plays a role in bearing load and improving the strength of the alloy.
[0031] In a specific embodiment, the volume proportion of the B19'-NiTiHf matrix phase is 52% to 75%, the volume proportion of the Ti3Sn phase is 22% to 40%, and the volume proportion of the (Ti, Hf)2Ni phase is 3% to 8%.
[0032] By controlling the volume ratio of B19'-NiTiHf matrix phase, Ti3Sn phase and (Ti,Hf)2Ni phase, the high-temperature shape memory effect and superelastic properties of the alloy can be further improved.
[0033] A second aspect of the present invention provides a method for preparing the above alloy, comprising the following steps:
[0034] The Ni metal, Ti metal, Hf metal and Sn metal are uniformly mixed, smelted at a temperature not lower than 2227°C, and after the metal components in the molten solution are uniform, cooled to room temperature to obtain an ingot;
[0035] The ingot is kept at 850-1000° C. for 0.5-4 hours and then cooled to room temperature.
[0036] The Ni metal, Ti metal, Hf metal and Sn metal are uniformly mixed and smelted at a temperature not lower than 2227° C. The Ni metal, Ti metal, Hf metal and Sn metal are melted into liquid. The metal components in the molten solution are made uniform by stirring or other methods, and then cooled to room temperature to obtain an ingot.
[0037] During the cooling process of the molten solution, due to the fast cooling rate and non-equilibrium solidification, the four metal components will have uneven distribution problems, resulting in uneven composition of the B19'-NiTiHf matrix phase and reducing the content of lamellar eutectic structure, so the ingot needs to be subsequently processed.
[0038] After the ingot is kept at 850-1000℃ for 0.5-4h, the principle of high temperature atomic diffusion is used to make the four metal components reach a uniform state again, which is conducive to the formation of the B19'-NiTiHf matrix phase and the Ti3Sn phase and the formation of the alternating lamellar structure, and then cooled to room temperature. In this cooling process, since it is cooling in the solid state, not a crystallization solidification process, it will not affect the uniform distribution of the four metal components, and thus will not affect the B19'-NiTiHf matrix phase and the Ti3Sn phase with the alternating lamellar structure that have been formed.
[0039] The ingot is kept at 850-1000° C. for 0.5-4 hours and then cooled to room temperature.
[0040] In a specific embodiment, a vacuum arc melting furnace is used for the melting process.
[0041] Using a vacuum arc melting furnace for melting has the advantages of anti-oxidation and high heating temperature.
[0042] In a specific implementation manner, the current of the vacuum arc melting furnace is 200-400A, and the melting time is 60-120S.
[0043] Under this condition, the four metal components can be made more uniform and achieve better smelting effect.
[0044] In a specific embodiment, the vacuum arc melting furnace is used for repeated melting 4 to 8 times.
[0045] The repeated melting of the present invention refers to placing a mixture of four metals in a vacuum arc melting furnace to obtain a molten liquid, then cooling the molten liquid to a solid state, turning it over in the vacuum arc melting furnace, turning on the arc to melt it again, and repeating the above operation. The purpose of repeated melting is to make the four metal components more uniformly distributed and promote the formation of the B19'-NiTiHf matrix phase and the Ti3Sn phase.
[0046] In a specific implementation, the cooling method is one of furnace cooling, water cooling and air cooling.
[0047] The difference between furnace cooling, water cooling and air cooling lies in the different cooling rates after solution heat treatment.
[0048] Furthermore, the cooling method is water cooling.
[0049] A third aspect of the present invention provides a temperature driving device, comprising the above alloy or an alloy prepared according to the above method.
[0050] The temperature driving device of the present invention can be used in an environment higher than 100°C, and the highest service temperature can even reach 250°C.
[0051] The solution provided by the present invention is further described below in conjunction with specific embodiments.
[0052] Example 1
[0053] According to the chemical formula of the alloy (Ni 50 Ti 35 Hf 15 ) 76 (Ti 75 Sn 25 ) 24， The masses of Ni metal, Ti metal, Hf metal and Sn metal were weighed to be 31.4 g, 30.0 g, 28.6 g and 10.0 g respectively, mixed evenly and placed in a vacuum arc melting furnace for melting treatment.
[0054] The operating conditions of the vacuum arc melting furnace are: the current is 300A, the melting time is 60S, and the vacuum arc melting furnace is used to repeatedly melt 6 times to obtain an ingot.
[0055] The ingot was kept at 900°C for 1 hour and furnace cooled to room temperature to obtain a NiTiHfSn high temperature shape memory alloy.
[0056] According to calculation, the volume proportion of the B19'-NiTiHf matrix phase is 75%; the volume proportion of the Ti3Sn phase is 22%; and the volume proportion of the (Ti,Hf)2Ni phase is 3%.
[0057] The XRD and SEM images of the NiTiHfSn high temperature shape memory alloy of this embodiment are shown in Figure 1 and Figure 2 .
[0058] from Figure 1 It can be seen that the NiTiHfSn high temperature shape memory alloy of this embodiment includes a B19'-NiTiHf matrix phase, a Ti3Sn phase and a (Ti,Hf)2Ni phase. Figure 2 , the light-colored area is the B19'-NiTiHf matrix phase, the dark-colored area is the Ti3Sn phase, and the B19'-NiTiHf matrix phase and the Ti3Sn phase are arranged alternately.
[0059] Example 2
[0060] This embodiment is basically consistent with the embodiment 1, except that after the ingot is kept at 900° C. for 1 hour, it is cooled to room temperature by air cooling.
[0061] Example 3
[0062] This embodiment is basically consistent with the embodiment 1, except that after the ingot is kept at 900° C. for 1 hour, it is cooled to room temperature by water cooling.
[0063] Example 4
[0064] This embodiment is basically the same as embodiment 1, except that: according to the chemical formula of the alloy (Ni 50 Ti 35 Hf 15 ) 68 (Ti 75 Sn 25 ) 32 The masses of Ni metal, Ti metal, Hf metal and Sn metal were weighed as 28.3 g, 32.4 g, 25.8 g and 13.5 g respectively.
[0065] According to calculation, the volume proportion of the B19'-NiTiHf matrix phase is 67.5%; the volume proportion of the Ti3Sn phase is 27.5%; and the volume proportion of the (Ti,Hf)2Ni phase is 5%.
[0066] Example 5
[0067] This embodiment is basically consistent with Embodiment 4, except that after the ingot is kept at 900° C. for 1 hour, it is cooled to room temperature by air cooling.
[0068] Example 6
[0069] This embodiment is basically consistent with the embodiment 1, except that after the ingot is kept at 900° C. for 1 hour, it is cooled to room temperature by water cooling.
[0070] Example 7
[0071] This embodiment is basically the same as embodiment 1, except that: according to the chemical formula of the alloy (Ni 50 Ti 35 Hf 15 ) 60 (Ti 75 Sn 25 ) 40 The masses of Ni metal, Ti metal, Hf metal and Sn metal were weighed as 25.2 g, 34.9 g, 23.0 g and 16.9 g respectively.
[0072] According to calculation, the volume proportion of the B19'-NiTiHf matrix phase is 52%; the volume proportion of the Ti3Sn phase is 40%; and the volume proportion of the (Ti,Hf)2Ni phase is 8%.
[0073] Example 8
[0074] This embodiment is basically consistent with Embodiment 7, except that after the ingot is kept at 900° C. for 1 hour, it is cooled to room temperature by air cooling.
[0075] Example 9
[0076] This embodiment is basically consistent with Embodiment 7, except that the ingot is kept at 900° C. for 1 hour and then cooled to room temperature by water cooling.
[0077] Example 10
[0078] This embodiment is basically the same as embodiment 1, except that: according to the chemical formula of the alloy (Ni 50 Ti 35 Hf 15 ) 84 (Ti 75 Sn 25 ) 16 The masses of Ni metal, Ti metal, Hf metal and Sn metal were weighed as 34.4 g, 27.6 g, 31.4 g and 6.6 g respectively.
[0079] According to calculation, the volume proportion of the B19'-NiTiHf matrix phase is 84%; the volume proportion of the Ti3Sn phase is 14%; and the volume proportion of the (Ti,Hf)2Ni phase is 2%.
[0080] Embodiment 11
[0081] This embodiment is basically the same as embodiment 1, except that the ingot is kept at 850°C for 0.5 hours and then cooled to room temperature.
[0082] Comparative Example 1
[0083] This comparative example uses NiTiHf alloy as a comparative example.
[0084] Comparative Example 2
[0085] This comparative example is based on the chemical formula Ni 46 Ti 38.2 Hf 13.8 The alloy of Sn2 was used as a comparative example.
[0086] The alloy of this comparative example introduces Sn into the NiTiHf alloy, but does not form a B19'-NiTiHf matrix phase and a Ti3Sn phase.
[0087] Comparative Example 3
[0088] This comparative example is basically consistent with Example 1, except that a non-vacuum high-frequency induction melting device is used for melting.
[0089] The alloys prepared in the examples and comparative examples were tested for martensitic transformation temperature, shape memory recovery deformation and superelastic recovery deformation. The test results are shown in Table 1.
[0090] The test method of martensitic transformation temperature is measured by DSC curve of the alloy with a temperature rise and fall of 10℃ / min.
[0091] The test method for shape memory recovery deformation is: the recovery deformation of the alloy measured by room temperature compression method plus the recovery deformation of heating at 500℃ for 10 minutes.
[0092] And the test method for superelastic recovery deformation: the recovery deformation of the alloy measured by 250℃ compression method.
[0093] Table 1 Performance test of alloys in embodiments and comparative examples
[0094]
[0095]
[0096] It can be seen from the above table that, compared with the comparative example, the shape memory alloy of the present invention has good high-temperature shape memory effect and superelastic performance.
[0097] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.
Claims
1. A shape memory alloy, characterized in that: Including eutectic structure; The eutectic structure includes a B19'-NiTiHf matrix phase and a Ti3Sn phase; The B19'-NiTiHf matrix phase and the Ti3Sn phase are alternately arranged in a lamellar structure.
2. The alloy according to claim 1, characterized in that It also includes (Ti,Hf)2Ni phase.
3. The alloy according to claim 2, characterized in that The volume proportion of the B19'-NiTiHf matrix phase is 52% to 75%, the volume proportion of the Ti3Sn phase is 22% to 40%, and the volume proportion of the (Ti, Hf)2Ni phase is 3% to 8%.
4. The alloy according to any one of claims 1 to 3, characterized in that The chemical formula of the alloy is (Ni 50 Ti 35 Hf 15 ) 100-4x (Ti 75 Sn 25 ) 4x , where 6≤x≤10.
5. A method for preparing the alloy according to any one of claims 1 to 4, characterized in that: The steps include: The Ni metal, Ti metal, Hf metal and Sn metal are uniformly mixed, smelted at a temperature not lower than 2227°C, and after the metal components in the molten solution are uniform, cooled to room temperature to obtain an ingot; The ingot is kept at 850-1000° C. for 0.5-4 hours and then cooled to room temperature.
6. The preparation method according to claim 5, characterized in that: The melting process is carried out using a vacuum arc melting furnace.
7. The preparation method according to claim 6, characterized in that: The current of the vacuum arc melting furnace is 200-400A, and the melting time is 60-120S.
8. The preparation method according to claim 7, characterized in that: Use a vacuum arc melting furnace to repeatedly melt 4 to 8 times.
9. The preparation method according to any one of claims 5 to 8, characterized in that: The cooling method is one of furnace cooling, water cooling and air cooling.
10. A temperature driving device, characterized in that: The invention comprises the alloy according to any one of claims 1 to 4 or the alloy prepared according to the preparation method according to any one of claims 5 to 9.