A Ti2448 alloy with anomalous thermal expansion in a wide temperature range and its preparation method

Abstract

A Ti2448 alloy with anomalous thermal expansion in a wide temperature range and its preparation method belong to the technical field of negative thermal expansion materials. In the present invention, by adjusting the component ratio of the alloy material, a matrix phase between the stable and unstable states is generated, and through forging, part of the matrix phase undergoes a phase change under the action of stress or temperature to generate a second phase. The lattice constants of the matrix phase and the second phase are respectively adjusted, and finally a Ti2448 alloy with anomalous thermal expansion in a wide temperature range is obtained. In the range of -200 to 300 °C, the macroscopic thermal expansion performance of the alloy is anisotropic, and the linear expansion coefficient in the rolling direction of the alloy satisfies -80 to -10 × ppm / K. The present invention effectively solves the problem of too high thermal expansion coefficient of titanium alloys, and can be applied to special occasions with high requirements for anisotropy; simplifies the production process of negative thermal expansion materials, does not require compounding with other materials, and does not require complex steps such as quenching and high-temperature solution treatment.

Description

Technical Field

[0001] The present invention belongs to the technical field of negative thermal expansion materials, and particularly relates to an anomalous thermal expansion Ti2448 alloy with a wide temperature range and a preparation method thereof. Background Art

[0002] Special functional materials play an increasingly important role in major strategic fields such as national defense security, aerospace, and precision manufacturing. Among them, negative thermal expansion metal materials are regarded as key frontier materials for solving the thermal stability problem of precision equipment because they have the ability to compensate and offset the thermal deformation of other components in the system. Negative thermal expansion refers to the anomalous "thermal shrinkage and cold expansion" behavior of materials within a certain temperature range. Currently, the discovered negative thermal expansion materials are very limited, and the vast majority are inorganic non-metallic materials, such as some special nitrides, carbon materials, etc. These non-metallic negative thermal expansion materials cannot be practically applied due to factors such as their excessively high cost, too low mechanical strength, and instability of the thermal expansion range and thermal expansion coefficient.

[0003] In contrast, metal materials have good toughness, impact resistance, and high processing plasticity. Therefore, the research and development of metal materials with high negative thermal expansion have broad practical value. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the present invention proposes an anomalous thermal expansion alloy with a wide temperature range and a preparation method thereof.

[0005] An anomalous thermal expansion Ti2448 alloy with a wide temperature range is composed of titanium, niobium, zirconium, tin, and oxygen atoms. The alloy composition by mass percentage is: niobium 23.5 - 24.5%, zirconium 3.9 - 4.05%, tin 7.7 - 8.2%, oxygen 0.05 - 0.15%, and the balance is Ti.

[0006] Furthermore, the alloy structure contains a nano-scale modulated structure, which is generated by a composition decomposition mechanism and is composed of a Nb-depleted structure and a Nb-rich structure. The Nb content in the Nb-depleted structure is less than 14wt.%, and the Nb content in the Nb-rich structure is greater than 16wt.%.

[0007] Furthermore, the alloy composition phase is composed of a high-symmetry matrix phase and a low-symmetry second phase.

[0008] Furthermore, in the alloy composition phase, the high-symmetry matrix phase has a cubic structure, and the low-symmetry second phase is an orthorhombic structure;

[0009] The high-symmetry matrix phase has a cubic structure, and the lattice constant of the cubic structure is 0.31 - 0.34 nm;

[0010] The low-symmetry second phase is in an orthorhombic structure, and the lattice constants of the second phase are: a is 0.29 - 0.315 nm, b is 0.46 - 0.52 nm, and c is 0.44 - 0.485 nm.

[0011] Further, in the temperature range of T1 - T2, the macroscopic thermal expansion property of the alloy is anisotropic, where: T1 = -200 °C, T2 = 300 °C.

[0012] Further, in the temperature range of T1 - T2, the linear expansion coefficient α in the rolling direction of the alloy satisfies: α1 ≤ α ≤ α2, where: T1 = -200 °C, T2 = 300 °C, α1 = -80 × ppm / K, and α2 = -10 × ppm / K.

[0013] Further, the macroscopic thermal expansion property of the alloy satisfies that the linear thermal expansion coefficient in the rolling direction is the lowest among all directions.

[0014] The preparation method of the above-mentioned wide-temperature-range anomalous thermal expansion alloy is carried out in the following steps in sequence:

[0015] Step 1: Using pure Ti, pure Nb, pure Zr, and Ti-Sn intermediate alloy as raw materials, adjusting the alloy composition ratio so that the ratio of the total number of valence electrons of the alloy constituent atoms to the total number of component atoms is 4.14 - 4.16, generating a parent phase between the stable and unstable states to obtain an initial alloy;

[0016] Step 2: By adjusting the composition and structure of the initial alloy described in Step 1, generating a second phase and maintaining its volume fraction at 10 - 30% to obtain an alloy containing the second phase; the adjustment method is: forging at 500 - 1000 °C, then cooling to 300 °C at a rate of 5 - 25 °C / min, holding for 10 min, and then cooling to room temperature at a cooling rate of 15 - 35 °C / min;

[0017] Step 3: Adjusting the lattice constant of the parent phase that has not undergone a phase change; the adjustment method is: hot-rolling the alloy containing the second phase at 300 - 700 °C, then cooling to 100 °C at a rate of 5 - 25 °C / min, holding for 20 min, and then cooling to room temperature at a rate of 15 - 35 °C / min and holding for 24 h to obtain the hot-rolled alloy;

[0018] Step 4: Further adjusting the preferred orientation and lattice constant of the second phase; the adjustment method is: subjecting the hot-rolled alloy to uniaxial tensile deformation with a deformation amount of 4.5 - 9% and a deformation rate of 0.1 - 1 mm / min - unloading to a deformation amount of 0% - heating to 150 °C - cooling to 30 °C - heating to 200 °C - cooling to 30 °C - heating to 250 °C - cooling to room temperature, where the heating and cooling rates are 10 °C / min.

[0019] Step 5: Obtain the wide-temperature-range anomalous thermal expansion alloy described above.

[0020] Further, in the said Step 1, the size of the initial alloy composition structure is 10 - 200 nm.

[0021] Further, in the said Step 2, the way to generate the second phase is that the parent phase undergoes a phase change under the action of stress or temperature.

[0022] Further, in the said Step 4, the preferred orientation of the second phase is manifested as the b-axis of the second phase being distributed along the rolling direction in Step 2.

[0023] The present invention provides a wide-temperature-range anomalous thermal expansion titanium alloy and its preparation method. The preparation scheme needs to strictly execute the given technical route, and the obtained titanium alloy has anisotropic negative thermal expansion performance. Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] 1. A negative thermal expansion titanium alloy is obtained, effectively solving the problem of too high thermal expansion coefficient of titanium alloy.

[0025] 2. An anisotropic negative thermal expansion material is provided, which can be applied to special occasions with high requirements for anisotropy.

[0026] 3. The production process of the negative thermal expansion material is simplified, without the need to be compounded with other materials, and without complex steps such as quenching and high-temperature solid solution treatment. Description of the Drawings

[0027] Figure 1 It is the thermal expansion performance curve of the Ti2448 alloy in Example 1 of the present invention.

[0028] Figure 2 It is the thermal expansion performance curve of the Ti2448 alloy in Example 2 of the present invention.

[0029] Figure 3 It is the thermal expansion performance curve of the Ti2448 alloy in Example 3 of the present invention.

[0030] Figure 4 It is the thermal expansion performance curve of the Ti2448 alloy in Example 4 of the present invention.

[0031] Figure 5 It is the thermal expansion performance curve of the Ti2448 alloy in Example 5 of the present invention. Detailed Embodiments

[0032] In order to make the purpose, technical solutions and advantages of the present invention clearer, the following further describes the present invention in detail with reference to embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0033] Example 1:

[0034] A preparation method of a Ti2448 alloy with anomalous thermal expansion in a wide temperature range is carried out in the following steps in sequence:

[0035] Step 1: Using pure Ti, pure Nb, pure Zr and Ti-Sn master alloy as raw materials, the alloy composition by mass percentage is: niobium 23.5%, zirconium 3.95%, tin 7.7%, oxygen 0.05%, and the balance is Ti. Adjust the alloy composition ratio so that the ratio of the total number of valence electrons of the alloy composition atoms to the total number of component atoms is 4.14, generating a parent phase between the stable and unstable states, obtaining an initial alloy, and the size of its component structure is 10 nm;

[0036] Step 2: After forging the initial alloy at 500 °C, cool it to 300 °C at a rate of 5 °C / min, hold for 10 min, and then cool it to room temperature at a cooling rate of 15 °C / min. Part of the parent phase undergoes a phase change under the action of stress or temperature, obtaining an alloy containing a second phase, and its volume fraction is 15%;

[0037] Step 3: Adjust the lattice constant of the parent phase that has not undergone a phase change: hot-roll the alloy containing the second phase at 300 °C, then cool it to 100 °C at a rate of 5 °C / min, hold for 20 min, and then cool it to room temperature at a rate of 15 °C / min, and hold for 24 h, obtaining the hot-rolled alloy;

[0038] Step 4: Further adjust the preferred orientation and lattice constant of the second phase: uniaxially stretch the hot-rolled alloy at a deformation rate of 0.1 mm / min until the deformation amount is 4.5%, then unload to a deformation amount of 0%, and then at a heating and cooling rate of 10 °C / min, heat up to 150 °C, cool to 30 °C, heat up to 200 °C, cool to 30 °C, heat up to 250, and cool to room temperature in sequence.

[0039] Step 5: Obtain the Ti2448 alloy with anomalous thermal expansion in the wide temperature range.

[0040] The Ti2448 alloy structure prepared contains a nanoscale modulated structure generated by the composition decomposition mechanism. The alloy consists of a Nb-poor structure and a Nb-rich structure, where the Nb content of the Nb-poor structure is 13 wt.%, and the Nb content of the Nb-rich structure is 17 wt.%. The alloy composition consists of a high-symmetry parent phase with a cubic structure and a low-symmetry second phase with an orthorhombic structure. Among them, the lattice constant of the cubic parent phase is 0.31 nm, the lattice constants of the orthorhombic second phase are a = 0.296 nm, b = 0.463 nm, and c = 0.445 nm, and the preferred orientation shows that the b-axis of the second phase is distributed along the rolling direction in step 2. The thermal expansion performance curve of the Ti2448 alloy is as Figure 1As shown, the linear thermal expansion coefficient in the rolling direction of the alloy is the lowest among all directions. In the range of -200°C to 300°C, the macroscopic thermal expansion properties of the alloy are anisotropic, and the linear expansion coefficient α in the rolling direction satisfies: α = -80 × ppm / K.

[0041] Example 2:

[0042] A preparation method of a Ti2448 alloy with anomalous thermal expansion in a wide temperature range is carried out in the following steps in sequence:

[0043] Step 1: Using pure Ti, pure Nb, pure Zr, and Ti-Sn intermediate alloy as raw materials, the alloy composition by mass percentage is: niobium 24.5%, zirconium 4.05%, tin 8.2%, oxygen 0.15%, and the balance is Ti. Adjust the alloy composition ratio so that the ratio of the total number of valence electrons of the alloy composition atoms to the total number of component atoms is 4.16, generating a parent phase between the stable and unstable states, and obtaining an initial alloy with the size of the component structure being 200 nm;

[0044] Step 2: After forging the initial alloy at 1000°C, cooling it to 300°C at a rate of 25°C / min, holding for 10 min, and then cooling to room temperature at a cooling rate of 35°C / min, part of the parent phase undergoes a phase change under the action of stress or temperature, obtaining an alloy containing a second phase with a volume fraction of 15%;

[0045] Step 3: Adjust the lattice constant of the parent phase that has not undergone a phase change: Hot-roll the alloy containing the second phase at 700°C, then cool it to 100°C at a rate of 25°C / min, hold for 20 min, and then cool to room temperature at a rate of 35°C / min, and hold for 24 h to obtain the hot-rolled alloy;

[0046] Step 4: Further adjust the preferred orientation and lattice constant of the second phase: Uniaxially stretch the hot-rolled alloy at a deformation rate of 1 mm / min until the deformation amount is 9%, then unload to a deformation amount of 0%, and then at a heating and cooling rate of 10°C / min, heat up to 150°C, cool to 30°C, heat up to 200°C, cool to 30°C, heat up to 250°C, and cool to room temperature in sequence.

[0047] Step 5: Obtain the Ti2448 alloy with anomalous thermal expansion in the wide temperature range.

[0048] The obtained Ti2448 alloy structure contains a nanoscale modulated structure generated by the component decomposition mechanism. The alloy consists of a Nb-poor structure and a Nb-rich structure, where the Nb content of the Nb-poor structure is 12 wt.%, and the Nb content of the Nb-rich structure is 18 wt.%. The alloy composition consists of a high-symmetry parent phase with a cubic structure and a low-symmetry second phase with an orthorhombic structure. Among them, the lattice constant of the cubic parent phase is 0.34 nm, and the lattice constants of the orthorhombic second phase are a = 0.312 nm, b = 0.515 nm, and c = 0.481 nm. The preferred orientation shows that the b-axis of the second phase is distributed along the rolling direction in step 2. The thermal expansion performance curve of the Ti2448 alloy is as Figure 2 shown. The linear thermal expansion coefficient in the rolling direction of the alloy is the lowest among all directions. In the range of -200 °C to 300 °C, the macroscopic thermal expansion performance of the alloy is anisotropic, and the linear expansion coefficient α in the rolling direction satisfies: α = -10 × ppm / K.

[0049] Example 3:

[0050] A preparation method of a Ti2448 alloy with anomalous thermal expansion in a wide temperature range is carried out in the following steps in sequence:

[0051] Step 1: Using pure Ti, pure Nb, pure Zr, and Ti-Sn intermediate alloy as raw materials, the alloy composition by mass percentage is: niobium 24%, zirconium 4%, tin 8%, oxygen 0.13%, and the balance is Ti. Adjust the alloy composition ratio so that the ratio of the total number of valence electrons of the alloy composition atoms to the total number of component atoms is 4.15, generating a parent phase between the stable and unstable states, and obtaining an initial alloy with a component structure size of 10 nm;

[0052] Step 2: After forging the initial alloy at 600 °C, cool it to 300 °C at a rate of 20 °C / min, hold for 10 min, and then cool it to room temperature at a cooling rate of 30 °C / min. Some parent phases undergo phase transformation under the action of stress or temperature, obtaining an alloy containing a second phase with a volume fraction of 30%;

[0053] Step 3: Adjust the lattice constant of the parent phase that has not undergone phase transformation: Carry out hot rolling on the alloy without the second phase at 600 °C, then cool it to 100 °C at a rate of 15 °C / min, hold for 20 min, and then cool it to room temperature at a rate of 20 °C / min, hold for 24 h, obtaining the hot-rolled alloy;

[0054] Step 4: Further adjust the preferred orientation and lattice constant of the second phase: Uniaxially stretch the hot-rolled alloy at a deformation rate of 0.5 mm / min until the deformation amount reaches 6%, then unload to a deformation amount of 0%. After that, at a heating and cooling rate of 10 °C / min, sequentially heat to 150 °C, cool to 30 °C, heat to 200 °C, cool to 30 °C, heat to 250 °C, and cool to room temperature.

[0055] Step 5: Obtain the wide-temperature-range anomalous thermal expansion Ti2448 alloy described above.

[0056] The microstructure of the prepared Ti2448 alloy contains nanoscale modulated structures generated by the composition decomposition mechanism. The alloy consists of a Nb-poor structure and a Nb-rich structure, where the Nb content of the Nb-poor structure is 10 wt.%, and the Nb content of the Nb-rich structure is 20 wt.%. The alloy composition consists of a high-symmetry parent phase with a cubic structure and a low-symmetry second phase with an orthorhombic structure. Among them, the lattice constant of the cubic-structured parent phase is 0.333 nm, and for the orthorhombic-structured second phase, the lattice constant a is 0.299 nm, b is 0.489 nm, c is 0.469 nm, and the preferred orientation shows that the b-axis of the second phase is distributed along the rolling direction in step 2. The thermal expansion performance curve of the Ti2448 alloy is as Figure 3 shown. The linear thermal expansion coefficient in the rolling direction of the alloy is the lowest among all directions. In the range of -200 °C to 300 °C, the macroscopic thermal expansion performance of the alloy is anisotropic, and the linear expansion coefficient α in the rolling direction satisfies: α = -30 × ppm / K.

[0057] Example 4:

[0058] A preparation method of a wide-temperature-range anomalous thermal expansion Ti2448 alloy is carried out in the following steps in sequence:

[0059] Step 1: Using pure Ti, pure Nb, pure Zr, and Ti-Sn intermediate alloy as raw materials, the alloy composition by mass percentage is: niobium 24%, zirconium 4%, tin 7.9%, oxygen 0.14%, and the balance is Ti. Adjust the alloy composition ratio so that the ratio of the total number of valence electrons of alloy composition atoms to the total number of component atoms is 4.145, generating a parent phase between the stable and unstable states, and obtaining an initial alloy with a component microstructure size of 10 nm;

[0060] Step 2: After forging the initial alloy at 800 °C, cool it to 300 °C at a rate of 18 °C / min, hold for 10 min, and then cool to room temperature at a cooling rate of 28 °C / min. Some of the parent phases undergo phase transformation under the action of stress or temperature, obtaining an alloy containing a second phase with a volume fraction of 25%;

[0061] Step 3: Adjust the lattice constant of the non-transformed parent phase: The alloy containing the second phase is hot-rolled at 600 °C, then cooled to 100 °C at a rate of 15 °C / min, held for 20 min, and then cooled to room temperature at a rate of 20 °C / min and held for 24 h to obtain the hot-rolled alloy;

[0062] Step 4: Further adjust the preferred orientation and lattice constant of the second phase: The hot-rolled alloy is uniaxially tensile deformed at a deformation rate of 0.9 mm / min to a deformation amount of 5.5%, then unloaded to a deformation amount of 0%, and then heated and cooled at a rate of 10 °C / min, successively heated to 150 °C, cooled to 30 °C, heated to 200 °C, cooled to 30 °C, heated to 250 °C, and cooled to room temperature.

[0063] Step 5: Obtain the wide-temperature-range anomalous thermal expansion Ti2448 alloy.

[0064] The microstructure of the prepared Ti2448 alloy contains a nanoscale modulated structure generated by the composition decomposition mechanism. The alloy consists of a Nb-poor structure and a Nb-rich structure, where the Nb content of the Nb-poor structure is 4 wt.%, and the Nb content of the Nb-rich structure is 22 wt.%. The alloy composition consists of a high-symmetry parent phase with a cubic structure and a low-symmetry second phase with an orthorhombic structure. Among them, the lattice constant of the cubic parent phase is 0.325 nm, the lattice constant a of the orthorhombic second phase is 0.293 nm, b is 0.491 nm, c is 0.473 nm, and the preferred orientation shows that the b-axis of the second phase is distributed along the rolling direction in step 2. The thermal expansion performance curve of the Ti-2448 alloy is as Figure 4 shown. The linear thermal expansion coefficient in the rolling direction of the Ti2448 alloy is the lowest among all directions. In the range of -200 °C to 300 °C, the macroscopic thermal expansion performance of the alloy is anisotropic, and the linear expansion coefficient α in the rolling direction satisfies: α = -40 × ppm / K.

[0065] Example 5:

[0066] A preparation method of a wide-temperature-range anomalous thermal expansion Ti2448 alloy is carried out in the following steps in sequence:

[0067] Step 1: Using pure Ti, pure Nb, pure Zr and Ti-Sn master alloy as raw materials, the alloy composition is in mass percentage content: niobium 24%, zirconium 3.9%, tin 7.8%, oxygen 0.11%, and the balance is Ti. Adjust the alloy composition ratio so that the ratio of the total number of valence electrons of alloy composition atoms to the total number of component atoms is 4.148, generating a parent phase between the stable and unstable states, and obtaining the initial alloy with the size of its composition structure being 10 nm;

[0068] Step 2: After forging the initial alloy at 650 °C, cool it to 300 °C at a rate of 20 °C / min, hold for 10 min, and then cool it to room temperature at a cooling rate of 30 °C / min. Some of the parent phase undergoes a phase transformation under the action of stress or temperature to obtain an alloy containing a second phase, and its volume fraction is 28%;

[0069] Step 3: Adjust the lattice constant of the parent phase that has not undergone a phase transformation: Hot-roll the alloy containing the second phase at 500 °C, then cool it to 100 °C at a rate of 15 °C / min, hold for 20 min, and then cool it to room temperature at a rate of 20 °C / min, and hold for 24 h to obtain the hot-rolled alloy;

[0070] Step 4: Further adjust the preferred orientation and lattice constant of the second phase: Uniaxially stretch the hot-rolled alloy at a deformation rate of 0.15 mm / min until the deformation amount reaches 6%, then unload to a deformation amount of 0%, and then heat and cool at a rate of 10 °C / min, heat up to 150 °C, cool to 30 °C, heat up to 200 °C, cool to 30 °C, heat up to 250 °C, and cool to room temperature in turn.

[0071] Step 5: Obtain the wide-temperature-range anomalous thermal expansion Ti2448 alloy.

[0072] The microstructure of the prepared Ti2448 alloy contains a nanoscale modulated structure generated by the compositional decomposition mechanism. The alloy consists of a Nb-depleted structure and a Nb-rich structure, where the Nb content of the Nb-depleted structure is 7 wt.%, and the Nb content of the Nb-rich structure is 21 wt.%. The alloy composition consists of a high-symmetry parent phase with a cubic structure and a low-symmetry second phase with an orthorhombic structure. Among them, the lattice constant of the cubic parent phase is 0.324 nm, the lattice constant a of the orthorhombic second phase is 0.294 nm, b is 0.485 nm, c is 0.467 nm, and the preferred orientation shows that the b-axis of the second phase is distributed along the rolling direction in step 2. The thermal expansion performance curve of the Ti2448 alloy is as Figure 5 shown. The linear thermal expansion coefficient of the Ti2448 alloy in the rolling direction is the lowest among all directions. In the range of -200 °C to 300 °C, the macroscopic thermal expansion performance of the alloy is anisotropic, and the linear expansion coefficient α in the rolling direction satisfies: α = -49 × ppm / K.

Claims

1. A method for preparing Ti2448 alloy with abnormal thermal expansion in a wide temperature range, characterized in that: It is composed of titanium, niobium, zirconium, tin and oxygen atoms, and the alloy composition by mass percentage is: niobium 23.5% to 24.5%, zirconium 3.9% to 4.05%, tin 7.7% to 8.2%, oxygen 0.05% to 0.15%, and the balance is Ti; In the temperature range of T1 to T2, the macroscopic thermal expansion properties of the alloy are anisotropic, and the linear expansion coefficient α of the alloy in the rolling direction satisfies: α1≤α≤α2; where: T1 = -200℃, T2 = 300℃, α1 = -80×ppm / K, α2 = -10×ppm / K; The preparation method of the alloy is specifically carried out in the following steps: Step 1: Using pure Ti, pure Nb, pure Zr, and a Ti-Sn master alloy as raw materials, the alloy composition ratio is adjusted so that the ratio of the total number of valence electrons of the alloy constituent atoms to the total number of component atoms is 4.14 to 4.16, thereby generating a parent phase between a stable and unstable state to obtain an initial alloy; Step 2: By adjusting the composition and structure of the initial alloy described in step 1, a portion of the parent phase undergoes a phase transformation to generate a second phase, thereby obtaining an alloy containing the second phase; Step 3: Adjust the lattice constant of the parent phase that has not undergone phase transformation, hot-roll the alloy containing the second phase, and then cool and hold the alloy to obtain a hot-rolled alloy; Step 4: further adjusting the preferred orientation and lattice constant of the second phase by subjecting the hot-rolled alloy to uniaxial stretching, continuous heating and cooling steps, and finally cooling to room temperature; Step 5: obtaining the wide temperature range abnormal thermal expansion alloy; In the step 1, the size of the initial alloy component structure is 10 to 200 nm; In step 2, the adjustment method is: forging at 500-1000° C., then cooling to 300° C. at a rate of 5-25° C. / min, holding for 10 minutes, and then cooling to room temperature at a cooling rate of 15-35° C. / min; the second phase is generated by a phase transformation of the parent phase under stress or temperature; the volume fraction of the second phase is 10%-30%; In step 3, the adjustment method is: hot rolling at 300-700°C, then cooling to 100°C at a rate of 5-25°C / min, keeping warm for 20 minutes, then cooling to room temperature at a rate of 15-35°C / min, and keeping warm for 24 hours; In step 4, the adjustment method is: uniaxial tensile deformation, deformation amount 4.5% to 9%, deformation rate 0.1 to 1 mm / min-unloading to deformation amount 0%-heating to 150°C-cooling to 30°C-heating to 200°C-cooling to 30°C-heating to 250°C-cooling to room temperature, wherein the heating and cooling rates are 10°C / min.

2. The method for preparing a Ti2448 alloy with anomalous thermal expansion in a wide temperature range according to claim 1, wherein: The alloy structure contains a nanoscale modulation structure generated by a component decomposition mechanism and composed of a Nb-poor structure and a Nb-rich structure, wherein the Nb content of the Nb-poor structure is less than 14wt.%, and the Nb content of the Nb-rich structure is greater than 16wt.%.

3. The method for preparing a Ti2448 alloy with abnormal thermal expansion in a wide temperature range according to claim 1, characterized in that: The alloy constituent phases include a highly symmetric parent phase; The high-symmetry mother phase has a cubic structure, and the lattice constant of the cubic structure is 0.31-0.34 nm.

4. The method for preparing a Ti2448 alloy with abnormal thermal expansion in a wide temperature range according to claim 1, characterized in that: The alloy constituent phases include a low-symmetry second phase; The low-symmetry second phase is an orthorhombic structure, and the lattice constants a of the second phase are 0.29 to 0.315 nm, b are 0.46 to 0.52 nm, and c are 0.44 to 0.485 nm.

5. The method for preparing a Ti2448 alloy with abnormal thermal expansion in a wide temperature range according to claim 1, characterized in that: The macroscopic thermal expansion properties of the alloy satisfy the following requirements: the linear thermal expansion coefficient in the rolling direction is the lowest in all directions.

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