High-strength ti-ni-co-nb alloy with constant-elasticity over wide temperature range and preparation method thereof

Abstract

The application provides a high-strength TiNiCoNb alloy with wide-temperature-range constant-elasticity characteristics and a preparation method thereof. x Ni y Co z Nb a ; wherein x=45-47, y=33-36, z=15-18, and a=2-4. The preparation method of the high-strength TiNiCoNb alloy with wide-temperature-range constant-elasticity characteristics comprises the following steps: selecting elemental titanium, nickel, cobalt and niobium with a purity of more than 99 wt.% according to the component proportion of the TiNiCoNb alloy; placing the elemental titanium, nickel, cobalt and niobium into a smelting furnace with a vacuum degree higher than 10 ‑1 Pa or inert gas protection, and smelting into the TiNiCoNb alloy. The application adds the element Nb to the TiNiCo alloy to obtain a high-strength alloy with wide-temperature-range constant-elasticity characteristics, and the yield strength of the alloy is unexpectedly improved by adding the element Nb.

Description

Technical Field

[0001] This invention relates to a high-strength TiNiCoNb alloy with wide-temperature-range constant elasticity and its preparation method, belonging to the field of materials technology. Background Technology

[0002] The Allynwa effect refers to the property of an alloy whose elastic modulus remains almost constant within a certain temperature range. This effect was first discovered in Fe-Ni-Cr alloys by the French scientist Guillaume in 1919. Due to this unique property, Allynwa alloys have been widely used in precision instruments, meters, communication technology, aerospace, and other fields. Although the Allynwa effect has been known for over a century, its mechanism has been the subject of much debate. Traditionally, it is believed to be related to magnetostriction in ferromagnetic materials, or the transition from ferromagnetic to paramagnetic, or from antiferromagnetic to paramagnetic. Recently, the Allynwa effect has also been observed in Co-doped TiNi alloys, which researchers suggest is related to a strain-induced glass transition in the alloy.

[0003] Strain glass is a relatively new concept. It is formed by doping alloys capable of martensitic transformation with excessive defects to suppress long-range ordered martensitic transformation. The doped defects are mainly point defects, line defects, and volume defects. Similar to the transformation of ferroelectric systems into relaxor ferroelectrics and ferromagnetic systems into spin glasses, strain glass is a product of the conjugate glass transition in ferroelastic / martensitic systems. Studies have found that strain glass transition has several characteristics: the parent phase maintains its B2 structure throughout the cooling process; the microstructure contains nanodomains; the resistivity increases abnormally; the storage modulus is frequency-dependent; and it exhibits non-ergodicity. Although there are increasing reports that the Elinvar effect is related to strain glass transition, this report on TiNiCo Elinvar alloys (CUI J, REN X. Elinvar effect in Co-doped TiNi strain glassalloys[J]. Applied Physics Letters, 2014, 105(6): 061904) does not provide four pieces of evidence for strain glass transition in the alloy. Moreover, according to the figure in the report, Ti 50 Ni 35 Co 15 The elastic modulus of the alloy is almost independent of temperature between 35 ℃ and 201 ℃, exhibiting the characteristics of Ailingwa. However, when the temperature drops to around -25 ℃, the elastic modulus decreases sharply, and the temperature coefficient at which it decreases is very large.

[0004] Therefore, how to improve the Allingwa effect of TiNiCo alloys is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] To address the aforementioned technical problems, the present invention aims to provide a TiNiCoNb alloy that improves the Allingwa effect of the TiNiCo alloy by adding Nb to broaden the domain transformation temperature range and the constant elastic temperature range.

[0006] To achieve the above objectives, this invention provides a high-strength TiNiCoNb alloy with wide-temperature-range constant elasticity, wherein the elemental composition of the alloy is: Ti x Ni y Co z Nb a ;

[0007] Where x=45-47, y=33-36, z=15-18, a=0.5-4 (preferably 2-4).

[0008] According to a specific embodiment of the present invention, preferably, the elemental composition of the alloy is Ti. 45 Ni 36 Co 15 Nb4 or Ti 47 Ni 33 Co 18 Nb2.

[0009] This invention significantly broadens the domain transformation temperature range and constant elastic temperature range of TiNiCo alloy by adding Nb element. During the cooling process, the elastic modulus of the alloy does not soften drastically, thereby improving the Allynwa effect of TiNiCo alloy. Moreover, Nb element will also dissolve into the matrix, playing a solid solution strengthening role, which can significantly improve the strength of the alloy.

[0010] This invention also provides a method for preparing the above-mentioned high-strength TiNiCoNb alloy with wide-temperature-range constant elasticity, which includes the following steps:

[0011] The composition ratio (molar ratio) of the TiNiCoNb alloy is selected from elemental titanium, nickel, cobalt and niobium with a purity of more than 99 wt.%.

[0012] Elemental titanium, nickel, cobalt, and niobium are placed in a vacuum with a degree higher than 10. -1 TiNiCoNb alloy is smelted in a furnace protected by Pa or inert gas.

[0013] According to a specific embodiment of the present invention, preferably, the preparation method further includes: casting the TiNiCoNb alloy obtained by melting into an ingot.

[0014] According to a specific embodiment of the present invention, preferably, the preparation method further includes: hot pressing, hot rolling, and cold drawing of the ingot to obtain wire.

[0015] According to a specific embodiment of the present invention, preferably, the preparation method further includes the step of annealing the filament.

[0016] According to a specific embodiment of the present invention, preferably, the diameter of the filament is 0.3 mm.

[0017] According to a specific embodiment of the present invention, preferably, hot pressing and hot rolling of the ingot is to form the ingot into a material with a diameter of 1 mm.

[0018] According to a specific embodiment of the present invention, preferably, the hot pressing temperature is 880-980℃ and the heat preservation time is 30-60min.

[0019] According to a specific embodiment of the present invention, preferably, the hot rolling temperature is 650-850℃ and the holding time is 10-20min.

[0020] According to a specific embodiment of the present invention, preferably, the annealing treatment is performed at a temperature of 350-750°C for a time of 10-20 minutes.

[0021] This invention adds Nb to a TiNiCo alloy, successfully obtaining a high-strength alloy with wide-temperature-range constant elasticity through appropriate proportioning. The TiNiCoNb alloy exhibits constant elasticity in a temperature range of -130 ℃ to 200 ℃, nearly doubling the Elinwale effect temperature range compared to the alloy without Nb. Under the same treatment conditions, the yield strength of the Nb-added TiNiCoNb alloy is significantly higher than that of the TiNiCo alloy, demonstrating an unexpectedly high improvement in yield strength through the addition of Nb. Attached Figure Description

[0022] Figure 1a and Figure 1b Ti, respectively, of Comparative Example 1 50 Ni 35 Co 15 Alloy and Ti of Example 2 47 Ni 33 Co 18 Variable-temperature X-ray diffraction pattern of Nb2.

[0023] Figure 2a and Figure 2b The figures show the elastic modulus-temperature normalized curves (373 K) and the temperature coefficient of elastic modulus for different alloys.

[0024] Figure 3 The stress-strain curve of the alloy after annealing at 600 °C for 20 min. Detailed Implementation

[0025] In order to provide a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail below, but it should not be construed as limiting the scope of implementation of the present invention.

[0026] Example 1

[0027] This embodiment provides a Ti 45 Ni 36 Co 15 Nb4 alloy, which is prepared by the following steps:

[0028] Ti 45 Ni 36 Co 15 The composition of Nb4 alloy is selected from elemental titanium, nickel, cobalt and niobium with a purity of 99.99 wt.% or higher;

[0029] Elemental titanium, nickel, cobalt, and niobium are placed in a vacuum with a degree higher than 10. -1 In a melting furnace protected by Pa or inert gas, TiNiCoNb alloy is smelted and cast into ingots;

[0030] The ingot was hot-pressed and hot-rolled to a diameter of 1 mm, then cold-drawn into an amorphous state, ultimately becoming a fine wire with a diameter of approximately 0.3 mm. Subsequently, the sample was annealed at different temperatures to recrystallize it, yielding Ti. 45 Ni 36 Co 15 Nb4 alloy.

[0031] Example 2

[0032] This embodiment provides a Ti 47 Ni 33 Co 18 The Nb2 alloy is prepared by the following steps:

[0033] Ti 47 Ni 33 Co 18 The composition of Nb2 alloy is selected from elemental titanium, nickel, cobalt and niobium with a purity of 99.99 wt.% or higher;

[0034] Elemental titanium, nickel, cobalt, and niobium are placed in a vacuum with a degree higher than 10. -1 In a melting furnace protected by Pa or inert gas, TiNiCoNb alloy is smelted and cast into ingots;

[0035] The ingot was hot-pressed and hot-rolled to a diameter of 1 mm, then cold-drawn into an amorphous state, ultimately becoming a fine wire with a diameter of approximately 0.3 mm. Subsequently, the sample was annealed at different temperatures to recrystallize it, yielding Ti. 47 Ni33 Co 18 Nb2 alloy.

[0036] Comparative Example

[0037] This comparative example provides a Ti 50 Ni 35 Co 15 The alloy is prepared through the following steps:

[0038] Ti 50 Ni 35 Co 15 The alloy composition is selected from elemental titanium, nickel, cobalt, and niobium with a purity of 99.99 wt.% or higher;

[0039] Elemental titanium, nickel, cobalt, and niobium are placed in a vacuum with a degree higher than 10. -1 In a melting furnace protected by Pa or inert gas, Ti is smelted into 50 Ni 35 Co 15 Alloy, cast to obtain ingot;

[0040] The ingot was hot-pressed and hot-rolled to a diameter of 1 mm, then cold-drawn into an amorphous state, ultimately becoming a fine wire with a diameter of approximately 0.3 mm. Subsequently, the sample was annealed at different temperatures to recrystallize it, yielding Ti. 50 Ni 35 Co 15 alloy.

[0041] Performance testing:

[0042] The dynamic mechanical properties of materials during phase transition processes were measured using a TA Q800 Dynamic Mechanical Analyzer (DMA). In this invention, a tensile mode was used, where a sample approximately 25 mm in length was fixed to a fixture, and a displacement amplitude of 10 μm was applied to measure the stress response at different frequencies (0.2 Hz–20 Hz). The test temperature range was -130 °C to 200 °C, with a heating / cooling rate of 2 °C / min. By recording the corresponding stress (or strain) response, the elastic modulus and damping changes of the sample at different frequencies within this temperature range were obtained.

[0043] In-situ heating and cooling experiments were conducted using a Rigaku 007HF transmission X-ray diffractometer. A high-throughput Mo rotating target was used, with a voltage of 50 kV and a wavelength of 0.07093 nm. This invention analyzed and tested the microstructure of different alloy samples during in-situ heating and cooling processes.

[0044] The mechanical properties of the material at high temperature, room temperature, and low temperature were tested using a WDTⅡ-20 universal tensile testing machine. The wire used for the tensile test was approximately 50 mm-60 mm in length. After cutting the required wire, it was first heat-treated (annealed at 600℃ for 20 min) before the tensile test. The loading / unloading rate during the tensile test was 0.05 mm / s.

[0045] Ehringer effect of alloys:

[0046] To understand the structural changes of the alloy during the cooling process, Ti alloy annealed at 600 °C for 20 min was first subjected to... 50 Ni 35 Co 15 Alloys and Ti 47 Ni 33 Co 18 In-situ heating and cooling XRD tests were performed on the Nb2 alloy, and the results are as follows: Figure 1a and Figure 1b As shown. In Figure 1a and Figure 1b In the middle, the curves at the bottom correspond to the following temperatures from bottom to top: 25℃, 0℃, -25℃, -50℃, -75℃, -100℃, -125℃, -150℃, and -180℃.

[0047] Depend on Figure 1a and Figure 1b It can be seen that Ti 50 Ni 35 Co 15 The alloy exhibited an R-phase peak at temperatures below -150 °C, indicating that the alloy did not undergo a strain glass transition with decreasing temperature, but rather an R-phase transformation. The addition of Nb to Ti... 47 Ni 33 Co 18 The Nb2 alloy did not undergo a phase transformation as the test temperature decreased, and it always maintained the B2 structure.

[0048] Comparison of elastic moduli of different alloys:

[0049] Figure 2a The normalized elastic modulus curves of the three alloys after annealing at 600℃ for 20 min are shown. Since the data of the samples are basically the same in the frequency range of 0.2 Hz-20 Hz, the test data at 1 Hz was selected for plotting. For ease of comparison, the elastic modulus was normalized to E (373K). In addition, the temperature coefficient of elastic modulus of the alloys at 1 Hz was calculated, and values ​​were plotted at 50℃ intervals in the range of -120℃ to 180℃. Figure 2b ( ), in order to observe its changes.

[0050] Depend on Figure 2a and Figure 2bIt is clear that Ti 50 Ni 35 Co 15 The elastic modulus of the alloy begins to soften sharply around -25 °C, while neither of the two alloys with added Nb exhibits this phenomenon. Statistical analysis of the temperature coefficient of elastic modulus also shows that the alloys with added Nb have very small and consistently stable coefficients, while Ti... 50 Ni 35 Co 15 The alloy's modulus increases rapidly when cooled to low temperatures. Based on the XRD test results, it is speculated that the addition of Nb element lowers the martensitic transformation temperature of the alloy. Therefore, the alloy did not undergo a phase transformation but a domain transformation throughout the entire test temperature range. As a result, the elastic modulus remained relatively stable between -130℃ and 200℃, without any drastic softening.

[0051] The two alloys with added Nb showed minimal change in elastic modulus as temperature decreased; even at -130℃, the modulus did not exhibit drastic softening. This is because Nb lowers the phase transformation temperature, and the tested temperature range is much higher than that of M. s This is the cause.

[0052] Mechanical properties of alloys

[0053] The mechanical properties of the three alloys after annealing at 600℃ for 20 min were tested, such as... Figure 3 As shown.

[0054] Depend on Figure 3 It can be seen that the strength of the alloy with added Nb is significantly improved. Ti 50 Ni 35 Co 15 The alloy has a yield strength of 0.32 GPa and an elongation of 72.81%; Ti 45 Ni 36 Co 15 The Nb4 alloy has a yield strength of 1.02 GPa and an elongation of 33.17%; Ti 47 Ni 33 Co 18 The Nb2 alloy has a strength of 1.11 GPa and an elongation of 14.97%. The solid solution strengthening effect of Nb significantly improves the alloy's strength. Under the same treatment conditions, the Ti... 47 Ni 33 Co 18 Nb2 alloy is more than Ti 50 Ni 35 Co 15 The alloy's yield strength is more than three times higher.

[0055] In summary, this invention adds Nb to the TiNiCo alloy and, through appropriate proportions, successfully obtains a high-strength alloy with a wide temperature range of constant elasticity. The TiNiCoNb alloy exhibits constant elasticity in a temperature range of -130 ℃ to 200 ℃, and compared to the alloy without Nb, the Allynwa effect temperature range is nearly doubled.

[0056] Under the same treatment conditions, the yield strength of TiNiCoNb alloy with added Nb is more than 3 times higher than that of TiNiCo alloy. Moreover, the yield strength of the alloy in the coarse-grained state after annealing at 600 ℃ is still higher than 1 GPa. It can be seen that the addition of Nb has unexpectedly improved the yield strength of the alloy.

Claims

1. A high-strength TiNiCoNb alloy with a wide temperature range constant-elasticity property, wherein, The elemental composition of the alloy is: Ti x Ni y Co z Nb a ; Wherein, x=45-47, y=33-36, z=15-18, a=0.5-4.

2. The high-strength TiNiCoNb alloy with wide-temperature-range constant-elasticity properties of claim 1, wherein, a=2-4。 3. The high-strength TiNiCoNb alloy of claim 1, having a wide temperature range constant modulus characteristic, wherein, The elemental composition of the alloy is Ti 45 Ni 36 Co 15 Nb4or Ti 47 Ni 33 Co 18 Nb2.

4. The method for preparing high-strength TiNiCoNb alloy with wide temperature range constant elasticity property according to any one of claims 1-3, comprising the following steps: The purity of the elemental titanium, nickel, cobalt and niobium is above 99wt.%. Put titanium, nickel, cobalt, niobium into the smelting furnace with vacuum degree higher than 10 -1 Smelt into TiNiCoNb alloy in the smelting furnace with Pa or inert gas protection.

5. The production method according to claim 4, wherein, The method further comprises: The TiNiCoNb alloy obtained by melting is cast into ingot.

6. The production method according to claim 5, wherein The method further comprises: The ingot is subjected to hot pressing, hot rolling and cold drawing to obtain wire.

7. The production method according to claim 6, wherein The method further comprises the step of annealing the wire.

8. The method of making according to claim 6, wherein, The diameter of the wire is 0.3 mm.

9. The production method according to claim 6, wherein The temperature of the hot pressing is 880-980℃, and the holding time is 30-60 min.

10. The production method according to claim 6, wherein The temperature of the hot rolling is 650-850℃, and the holding time is 10-20 min.

11. The production method according to claim 7, wherein The temperature of the annealing is 350-750℃, and the time is 10-20 min.

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