Two-dimensional zero-expansion titanium alloy plate and preparation method thereof

Abstract

The invention relates to the field of titanium alloys, in particular to a two-dimensional zero-expansion titanium alloy plate and a preparation method thereof. The titanium alloy plate is composed of titanium, niobium, zirconium, tin and oxygen atoms, and the structure of the titanium alloy plate is composed of an orthogonal structure alpha ''phase and a body-centered cubic structure beta phase. The lattice mismatch strain and volume fraction of a precipitated phase and a parent phase in the alloy are adjusted by limiting the atomic ratio of Nb, Zr and Sn and a rolling process, so that the alloy obtains a low thermal expansion coefficient in the two-dimensional direction. The titanium alloy plate obtained through the method has the two-dimensional zero-expansion performance, the service temperature interval far exceeds that of an existing zero-expansion alloy material, and the use requirements of precise instruments can be well met. And meanwhile, solid solution and quenching treatment is not needed in the alloy preparation process, the preparation process is simplified, and the alloy preparation efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of titanium alloys, and in particular to a two-dimensional zero-expansion titanium alloy sheet and its preparation method. Background Technology

[0002] Precision instruments typically rely on highly accurate dimensional and positional information. If components within the instrument expand or contract due to temperature changes, it can lead to dimensional instability, affecting the instrument's performance and accuracy. Therefore, alloy materials with zero expansion properties are crucial in the field of precision instruments. Zero expansion means that the volume or dimension in a certain direction of the material remains almost unchanged under temperature variations, thus ensuring that the instrument maintains highly accurate performance under various temperature conditions. Currently, zero expansion alloy materials are mainly FeNi-based ferromagnetic materials. These materials cannot be used in electromagnetic fields, and their zero expansion temperature range is only -50 to 50°C, which cannot meet the requirements for use in extreme environments such as outer space.

[0003] In recent years, it has been discovered that titanium alloys can possess unidirectional zero expansion characteristics. Publication number CN115612893A proposes a titanium-niobium-tantalum alloy gasket with anisotropic thermal expansion properties and its preparation method. Through high-temperature homogenization, hot forging, annealing, and cold rolling, negative thermal expansion properties along the thickness direction are obtained, but it does not possess two-dimensional zero expansion characteristics. The technical solution does not involve limiting the atomic ratio of niobium, zirconium, and tin, nor does it involve adjusting the lattice mismatch strain through rolling and heat treatment processes. Publication number CN105886981A proposes an alloy seal with negative thermal expansion properties. Through plasma sintering, hot rolling, high-temperature heat treatment, and cold rolling, an alloy seal with unidirectional negative expansion is obtained, but it does not possess two-dimensional zero expansion characteristics. The technical solution does not involve limiting the atomic ratio of niobium, zirconium, and tin, nor does it involve adjusting the lattice mismatch strain through rolling and heat treatment processes. Publication number CN107164653A proposes a titanium-nickel alloy with negative thermal expansion properties and its preparation method. The alloy material with negative thermal expansion is obtained by adjusting the Ti and Ni composition and rapid solidification, but it does not possess two-dimensional zero expansion characteristics. The technical solution does not involve limiting the atomic ratios of niobium, zirconium, and tin, nor does it address the adjustment of lattice mismatch strain through rolling and heat treatment processes. In summary, currently there are no related technologies or inspirations that can provide two-dimensional zero-expansion titanium alloy sheets and their preparation methods. Summary of the Invention

[0004] To address the technical problem that current titanium alloys cannot achieve two-dimensional zero expansion properties, this invention provides a two-dimensional zero expansion titanium alloy sheet and its preparation method, solving the problem that existing titanium alloy sheets cannot meet the application requirements for two-dimensional zero expansion.

[0005] The technical solution of this invention is:

[0006] A two-dimensional zero-expansion titanium alloy sheet is provided. The titanium alloy sheet is composed of titanium, niobium, zirconium, tin and oxygen atoms. The constituent phases are composed of orthorhombic α″ phase and body-centered cubic β phase. In the temperature range of -200 to 300℃, the coefficient of thermal expansion of the titanium alloy sheet is less than 4ppm / ℃ along the rolling direction, less than 4ppm / ℃ along the transverse direction, and less than 4ppm / ℃ in any direction between the rolling direction and the transverse direction.

[0007] The two-dimensional zero-expansion titanium alloy sheet has the following titanium alloy composition by atomic percentage: Nb 12-17%, Zr 2-3%, Sn 3-5%, O 0.4-0.5%, with the balance being Ti.

[0008] The method for preparing the two-dimensional zero-expansion titanium alloy plate involves limiting the atomic ratio of Nb, Zr, and Sn and controlling the rolling process, thereby adjusting the phase stability, lattice mismatch strain, and volume fraction of the precipitated phase and the parent phase in the alloy, so that the alloy obtains a low coefficient of thermal expansion along the two-dimensional direction.

[0009] The preparation method of the two-dimensional zero-expansion titanium alloy sheet is carried out in the following steps:

[0010] (1) Control the alloy composition ratio so that the atomic percentages satisfy: Nb 12~17%, Zr 2~3%, Sn 3~5%, O 0.4~0.5%, with the balance being Ti, and Nb:Zr:Sn=(14.9~15.1):(2.4~2.6):(3.9~4.1);

[0011] (2) Press the alloy electrode and perform vacuum melting;

[0012] (3) Forging is carried out in the range of 650 to 1200℃, the deformation is controlled at 10 to 50%, and then cooled to room temperature at a cooling rate of 10 to 30℃ / minute.

[0013] (4) Control the rolling temperature and rolling direction, and perform rolling processing in the predetermined direction within the range of 300 to 650℃, with a deformation of 10 to 50%. After rolling, cool the material and control the cooling rate to 10 to 25℃ / minute.

[0014] (5) Control the rolling temperature and rolling direction, and perform rolling in the range of 300 to 550°C along a direction at 90 degrees to the predetermined direction, with a deformation of 10 to 50%. After rolling, cool the material and control the cooling rate to 10 to 25°C / minute.

[0015] (6) Control the rolling temperature and rolling direction, and perform rolling processing in the predetermined direction in step (4) within the range of 10 to 50°C, with a rolling deformation of 5 to 30%.

[0016] (7) Control the rolling temperature and rolling direction, and perform rolling processing in the range of 10 to 50°C along the predetermined direction in step (6) at a 90-degree angle, with a rolling deformation of 5 to 30%.

[0017] (8) Control the rolling temperature and rolling direction, and perform rolling processing in the range of 10 to 50°C along the predetermined direction in step (6) at a 30-degree angle, with a rolling deformation of 5 to 30%.

[0018] (9) Control the rolling temperature and rolling direction, and perform rolling processing in the range of 10 to 50°C along the predetermined direction in step (6) at a 60-degree angle, with a rolling deformation of 5 to 30%, and control the thickness of the titanium alloy plate to be 1 to 5 mm.

[0019] (10) The titanium alloy obtained in step (9) is subjected to heating-holding-cooling treatment. The heating rate is 50-500℃ / min, the holding temperature is 300-500℃, the holding time is 0.5-4 hours, and the cooling rate is 5-40℃ / min.

[0020] (11) The titanium alloy obtained in step (10) is subjected to a heating-cooling treatment. The heating rate is 3 to 20 °C / min, the temperature is raised to 250 to 400 °C, and the cooling rate is 3 to 30 °C / min.

[0021] (12) A two-dimensional zero-expansion titanium alloy plate with a thickness of 1-5 mm was obtained.

[0022] The working principle of this invention is as follows:

[0023] The technical features in this solution play a unique technical role. Adjusting the alloy composition ratio to achieve an atomic percentage of Nb:Zr:Sn = (14.9–15.1):(2.4–2.6):(3.9–4.1), with O at 0.4–0.5% and the balance being Ti, allows the alloy to maintain a single body-centered cubic structure at room temperature and enables subsequent processing to induce a continuous crystal structure transformation, producing an orthorhombic α″ phase. Forging is performed in the range of 650–1200℃, with deformation controlled at 10–50%, followed by cooling to room temperature at a rate of 10–30℃ / min, thereby improving the alloy's microstructure and properties. The stability of the parent phase allows for subsequent rolling processes. Rolling along the rolling direction at 300–650℃ with a deformation of 10–50%, followed by cooling at a controlled rate of 10–25℃ / min, ensures the alloy retains a single body-centered cubic structure after rolling, thus enabling the formation of orthorhombic precipitates during subsequent rolling. Rolling along the transverse direction at 300–550℃ with a deformation of 10–50% improves the transverse microstructure of the alloy. Rolling along the rolling direction at 10–50℃ with a deformation of 5–30% further enhances the alloy's transverse microstructure. A crystal structure transformation occurs along the rolling direction; transverse rolling at 10–50°C with a deformation of 5–30% causes a transverse crystal structure transformation in the alloy; rolling at 30°C with a deformation of 5–30% causes the α″ phase in the alloy to form a preferred orientation at 30°; rolling at 60°C with a deformation of 5–30% causes the α″ phase in the alloy to form a preferred orientation at 30°; controlling the thickness of the titanium alloy sheet to 1–5 mm ensures the alloy achieves uniform zero-expansion characteristics; the titanium alloy... The alloy undergoes a heating-holding-cooling process with a heating rate of 50–500 °C / min, a holding temperature of 300–500 °C, a holding time of 0.5–4 hours, and a cooling rate of 5–40 °C / min. This process regulates the composition and phase stability of α″, thereby improving the coefficient of thermal expansion and achieving zero expansion properties. The titanium alloy is then subjected to a heating-cooling process with a heating rate of 3–20 °C / min, reaching a temperature of 250–400 °C, followed by a cooling rate of 3–30 °C / min. This process improves the lattice mismatch strain between the parent phase and the precipitated phases, resulting in a more uniform two-dimensional thermal expansion coefficient. These effects are achieved through the synergistic effect of all parameters. This technical solution cannot include solution treatment or quenching, as both would disrupt the preferred orientation of the orthorhombic precipitated phases required for the alloy to achieve two-dimensional zero expansion properties, thus preventing the alloy from possessing these characteristics.

[0024] The advantages and beneficial effects of this invention are:

[0025] The titanium alloy sheet obtained by this invention has two-dimensional zero expansion properties, with a coefficient of thermal expansion of less than 4 ppm / ℃ over a wide temperature range of -200℃ to 300℃. Its service temperature range far exceeds that of existing zero expansion alloy materials, effectively meeting the requirements of precision instruments. Furthermore, the alloy preparation process eliminates the need for solution treatment and quenching, simplifying the process and improving preparation efficiency. Attached Figure Description

[0026] Figure 1 Schematic diagram of rolling direction.

[0027] Figure 2 Two-dimensional zero expansion coefficient. In the figure, the vertical axis CTE refers to the coefficient of thermal expansion.

[0028] Figure 3 Two-dimensional zero expansion coefficient. In the figure, the vertical axis CTE refers to the coefficient of thermal expansion.

[0029] Figure 4 Two-dimensional zero expansion coefficient. In the figure, the vertical axis CTE refers to the coefficient of thermal expansion.

[0030] Figure 5 Two-dimensional zero expansion coefficient. In the figure, the vertical axis CTE refers to the coefficient of thermal expansion. Detailed Implementation

[0031] To enable those skilled in the art to better understand the present invention, the technical solution of the present invention will be clearly and completely described below with reference to the embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0032] Example 1

[0033] In this embodiment, the titanium alloy sheet is composed of titanium, niobium, zirconium, tin and oxygen atoms; it is composed of orthorhombic α″ phase and body-centered cubic β phase; in the temperature range of -200 to 300℃, the coefficient of thermal expansion of the alloy is less than 4ppm / ℃ along the rolling direction, less than 4ppm / ℃ along the transverse direction, and less than 4ppm / ℃ in any direction between the rolling direction and the transverse direction.

[0034] In this embodiment, a method for preparing a two-dimensional zero-expansion titanium alloy sheet is described. By limiting the atomic ratio of Nb, Zr, and Sn and the rolling process, the lattice mismatch strain and volume fraction of the precipitated phase and the parent phase in the alloy are adjusted, thereby enabling the alloy to obtain a low coefficient of thermal expansion along the two-dimensional direction. The preparation method is carried out in the following steps:

[0035] (1) Control the alloy composition ratio to ensure that the atomic percentages are: Nb 15%, Zr 2.5%, Sn 4%, O 0.4%, with the balance being Ti;

[0036] (2) Press the alloy electrode and perform vacuum melting;

[0037] (3) Forging is carried out at 700℃ with a deformation of 15%, and then cooled to room temperature at 10℃ / min.

[0038] (4) Figure 1 As shown, the rolling temperature and rolling direction are controlled, and rolling is carried out at 300℃ along the predetermined direction with a deformation of 10%. After rolling, cooling is performed with a cooling rate of 10℃ / minute.

[0039] (5) Figure 1 As shown, the rolling temperature and rolling direction are controlled, and rolling is carried out at 550℃ along a direction at 90 degrees to the predetermined direction, with a deformation of 50%. After rolling, cooling is performed, and the cooling rate is controlled at 25℃ / minute.

[0040] (6) Figure 1 As shown, the rolling temperature and rolling direction are controlled, and rolling is performed at 50°C along the predetermined direction in step (4), with a rolling deformation of 30%.

[0041] (7) Figure 1 As shown, the rolling temperature and rolling direction are controlled, and the rolling process is carried out at 10°C in a direction of 90 degrees along the predetermined direction in step (6), with a rolling deformation of 5%.

[0042] (8) Figure 1 As shown, the rolling temperature and rolling direction are controlled, and the rolling process is carried out at 10°C in a 30-degree direction along the predetermined direction in step (6), with a rolling deformation of 30%.

[0043] (9) such as Figure 1 As shown, the rolling temperature and rolling direction are controlled, and the rolling process is carried out at 10°C in the direction of 60 degrees along the predetermined direction in step (6), with a rolling deformation of 30% and the thickness of the titanium alloy plate controlled to be 5mm.

[0044] (10) The titanium alloy obtained in step (9) is subjected to heating-holding-cooling treatment. The heating rate is 500℃ / min, the holding temperature is 350℃, the holding time is 4 hours, and the cooling rate is 40℃ / min.

[0045] (11) The titanium alloy obtained in step (10) is subjected to a heating-cooling treatment. The heating rate is 3℃ / min, the temperature is raised to 250℃, and the cooling rate is 3℃ / min.

[0046] (12) A two-dimensional zero-expansion titanium alloy plate with a thickness of 5 mm was obtained, which was composed of an orthogonal α″ phase and a body-centered cubic β phase; in the temperature range of -200 to 300℃, the coefficient of thermal expansion of the alloy was less than 2 ppm / ℃ along the rolling direction, less than 2 ppm / ℃ along the transverse direction, and less than 3 ppm / ℃ in any direction between the rolling direction and the transverse direction. Figure 2 ).

[0047] Example 2

[0048] In this embodiment, the titanium alloy sheet is composed of titanium, niobium, zirconium, tin and oxygen atoms; it is composed of orthorhombic α″ phase and body-centered cubic β phase; in the temperature range of -200 to 300℃, the coefficient of thermal expansion of the alloy is less than 4ppm / ℃ along the rolling direction, less than 4ppm / ℃ along the transverse direction, and less than 4ppm / ℃ in any direction between the rolling direction and the transverse direction.

[0049] In this embodiment, a method for preparing a two-dimensional zero-expansion titanium alloy sheet is described. By limiting the atomic ratio of Nb, Zr, and Sn and the rolling process, the lattice mismatch strain and volume fraction of the precipitated phase and the parent phase in the alloy are adjusted, thereby enabling the alloy to obtain a low coefficient of thermal expansion along the two-dimensional direction. The preparation method is carried out in the following steps:

[0050] (1) Control the alloy composition ratio to ensure that the atomic percentages are: Nb 14.9%, Zr 2.48%, Sn 3.97%, O 0.42%, with the balance being Ti;

[0051] (2) Press the alloy electrode and perform vacuum melting;

[0052] (3) Forging is carried out at 1150℃ with a deformation of 45%, and then cooled to room temperature at 30℃ / min.

[0053] (4) Figure 1 As shown, the rolling temperature and rolling direction are controlled, and rolling is carried out at 550℃ along the predetermined direction with a deformation of 50%. After rolling, cooling is performed with a cooling rate of 25℃ / minute.

[0054] (5) Figure 1 As shown, the rolling temperature and rolling direction are controlled, and rolling is carried out at 550℃ in a direction 90 degrees to the predetermined direction, with a deformation of 10%. After rolling, cooling is performed, and the cooling rate is controlled at 10℃ / minute.

[0055] (6) Figure 1 As shown, the rolling temperature and rolling direction are controlled, and rolling is performed at 15°C along the predetermined direction in step (4), with a rolling deformation of 5%.

[0056] (7) Figure 1As shown, the rolling temperature and rolling direction are controlled, and the rolling process is carried out at 10°C in a direction of 90 degrees along the predetermined direction in step (6), with a rolling deformation of 30%.

[0057] (8) Figure 1 As shown, the rolling temperature and rolling direction are controlled, and the rolling process is carried out at 10°C in a direction of 30 degrees along the predetermined direction in step (6), with a rolling deformation of 5%.

[0058] (9) such as Figure 1 As shown, the rolling temperature and rolling direction are controlled, and the rolling process is carried out at 10°C in a 60-degree direction along the predetermined direction in step (6), with a rolling deformation of 5% and the thickness of the titanium alloy plate controlled to be 5mm.

[0059] (10) The titanium alloy obtained in step (9) is subjected to heating-holding-cooling treatment. The heating rate is 50℃ / min, the holding temperature is 450℃, the holding time is 0.5 hours, and the cooling rate is 5℃ / min.

[0060] (11) The titanium alloy obtained in step (10) is subjected to a heating-cooling treatment. The heating rate is 20℃ / min, the temperature is raised to 400℃, and the cooling rate is 30℃ / min.

[0061] (12) A two-dimensional zero-expansion titanium alloy plate with a thickness of 5 mm was obtained, which was composed of an orthogonal α″ phase and a body-centered cubic β phase; in the temperature range of -200 to 300℃, the thermal expansion coefficient of the alloy was less than 3 ppm / ℃ along the rolling direction, less than 3 ppm / ℃ along the transverse direction, and less than 2 ppm / ℃ in any direction between the rolling direction and the transverse direction. Figure 3 ).

[0062] Example 3

[0063] In this embodiment, the titanium alloy sheet is composed of titanium, niobium, zirconium, tin and oxygen atoms; it is composed of orthorhombic α″ phase and body-centered cubic β phase; in the temperature range of -200 to 300℃, the coefficient of thermal expansion of the alloy is less than 4ppm / ℃ along the rolling direction, less than 4ppm / ℃ along the transverse direction, and less than 4ppm / ℃ in any direction between the rolling direction and the transverse direction.

[0064] In this embodiment, a method for preparing a two-dimensional zero-expansion titanium alloy sheet is described. By limiting the atomic ratio of Nb, Zr, and Sn and the rolling process, the lattice mismatch strain and volume fraction of the precipitated phase and the parent phase in the alloy are adjusted, thereby enabling the alloy to obtain a low coefficient of thermal expansion along the two-dimensional direction. The preparation method is carried out in the following steps:

[0065] (1) Control the alloy composition ratio to ensure that the atomic percentages are: Nb 16%, Zr 2.67%, Sn 4.27%, O 0.48%, with the balance being Ti;

[0066] (2) Press the alloy electrode and perform vacuum melting;

[0067] (3) Forging is carried out at 900℃ with a deformation of 25%, and then cooled to room temperature at 15℃ / min.

[0068] (4) Figure 1 As shown, the rolling temperature and rolling direction are controlled, and rolling is carried out at 300℃ along the predetermined direction with a deformation of 15%. After rolling, cooling is performed with a cooling rate of 12℃ / minute.

[0069] (5) Figure 1 As shown, the rolling temperature and rolling direction are controlled, and rolling is carried out at 450℃ along a direction at 90 degrees to the predetermined direction, with a deformation of 40%. After rolling, cooling is performed, and the cooling rate is controlled at 20℃ / minute.

[0070] (6) Figure 1 As shown, the rolling temperature and rolling direction are controlled, and rolling is performed at 25°C along the predetermined direction in step (4), with a rolling deformation of 25%.

[0071] (7) Figure 1 As shown, the rolling temperature and rolling direction are controlled, and the rolling process is carried out at 20°C in a direction of 90 degrees along the predetermined direction in step (6), with a rolling deformation of 10%.

[0072] (8) Figure 1 As shown, the rolling temperature and rolling direction are controlled, and the rolling process is carried out at 20°C in a direction of 30 degrees along the predetermined direction in step (6), with a rolling deformation of 20%.

[0073] (9) such as Figure 1 As shown, the rolling temperature and rolling direction are controlled, and the rolling process is carried out at 20°C in a 60-degree direction along the predetermined direction in step (6), with a rolling deformation of 20% and the thickness of the titanium alloy plate controlled to be 3mm.

[0074] (10) The titanium alloy obtained in step (9) is subjected to heating-holding-cooling treatment. The heating rate is 100℃ / min, the holding temperature is 450℃, the holding time is 2 hours, and the cooling rate is 20℃ / min.

[0075] (11) The titanium alloy obtained in step (10) is subjected to a heating-cooling treatment. The heating rate is 10℃ / min, the temperature is raised to 350℃, and the cooling rate is 15℃ / min.

[0076] (12) A two-dimensional zero-expansion titanium alloy plate with a thickness of 3 mm was obtained, composed of orthogonal α″ phase and body-centered cubic β phase; in the temperature range of -200 to 300℃, the coefficient of thermal expansion of the alloy is less than 1.5 ppm / ℃ along the rolling direction, less than 1.5 ppm / ℃ along the transverse direction, and less than 2 ppm / ℃ in any direction between the rolling direction and the transverse direction. Figure 4 ).

[0077] Example 4

[0078] In this embodiment, the titanium alloy sheet is composed of titanium, niobium, zirconium, tin and oxygen atoms; it is composed of orthorhombic α″ phase and body-centered cubic β phase; in the temperature range of -200 to 300℃, the coefficient of thermal expansion of the alloy is less than 4ppm / ℃ along the rolling direction, less than 4ppm / ℃ along the transverse direction, and less than 4ppm / ℃ in any direction between the rolling direction and the transverse direction.

[0079] In this embodiment, a method for preparing a two-dimensional zero-expansion titanium alloy sheet is described. By limiting the atomic ratio of Nb, Zr, and Sn and the rolling process, the lattice mismatch strain and volume fraction of the precipitated phase and the parent phase in the alloy are adjusted, thereby enabling the alloy to obtain a low coefficient of thermal expansion along the two-dimensional direction. The preparation method is carried out in the following steps:

[0080] (1) Control the alloy composition ratio to ensure that the atomic percentages are: Nb 15%, Zr 2.5%, Sn 4%, O 0.4%, with the balance being Ti;

[0081] (2) Press the alloy electrode and perform vacuum melting;

[0082] (3) Forging is carried out at 800℃ with a deformation of 25%, and then cooled to room temperature at 15℃ / min.

[0083] (4) Figure 1 As shown, the rolling temperature and rolling direction are controlled, and rolling is carried out at 300℃ along the predetermined direction with a deformation of 20%. After rolling, cooling is performed with a cooling rate of 10℃ / minute.

[0084] (5) Figure 1 As shown, the rolling temperature and rolling direction are controlled, and rolling is carried out at 550℃ along a direction at 90 degrees to the predetermined direction, with a deformation of 35%. After rolling, cooling is performed, and the cooling rate is controlled at 25℃ / minute.

[0085] (6) Figure 1 As shown, the rolling temperature and rolling direction are controlled, and rolling is performed at 50°C along the predetermined direction in step (4), with a rolling deformation of 10%.

[0086] (7) Figure 1As shown, the rolling temperature and rolling direction are controlled, and the rolling process is carried out at 10°C in a direction of 90 degrees along the predetermined direction in step (6), with a rolling deformation of 15%.

[0087] (8) Figure 1 As shown, the rolling temperature and rolling direction are controlled, and the rolling process is carried out at 10°C in a direction of 30 degrees along the predetermined direction in step (6), with a rolling deformation of 10%.

[0088] (9) such as Figure 1 As shown, the rolling temperature and rolling direction are controlled, and the rolling process is carried out at 10°C in a 60-degree direction along the predetermined direction in step (6), with a rolling deformation of 30% and the thickness of the titanium alloy plate controlled to be 3mm.

[0089] (10) The titanium alloy obtained in step (9) is subjected to heating-holding-cooling treatment. The heating rate is 500℃ / min, the holding temperature is 375℃, the holding time is 2.5 hours, and the cooling rate is 30℃ / min.

[0090] (11) The titanium alloy obtained in step (10) is subjected to a heating-cooling treatment. The heating rate is 13℃ / min, the temperature is raised to 250℃, and the cooling rate is 13℃ / min.

[0091] (12) A two-dimensional zero-expansion titanium alloy plate with a thickness of 3 mm was obtained, which was composed of an orthogonal α″ phase and a body-centered cubic β phase; in the temperature range of -200 to 300℃, the thermal expansion coefficient of the alloy was less than 2 ppm / ℃ along the rolling direction, less than 2 ppm / ℃ along the transverse direction, and less than 3 ppm / ℃ in any direction between the rolling direction and the transverse direction. Figure 5 ).

[0092] Example 5

[0093] In this embodiment, the titanium alloy sheet is composed of titanium, niobium, zirconium, tin and oxygen atoms; it is composed of orthorhombic α″ phase and body-centered cubic β phase; in the temperature range of -200 to 300℃, the coefficient of thermal expansion of the alloy is less than 4ppm / ℃ along the rolling direction, less than 4ppm / ℃ along the transverse direction, and less than 4ppm / ℃ in any direction between the rolling direction and the transverse direction.

[0094] In this embodiment, a method for preparing a two-dimensional zero-expansion titanium alloy sheet is described. By limiting the atomic ratio of Nb, Zr, and Sn and the rolling process, the lattice mismatch strain and volume fraction of the precipitated phase and the parent phase in the alloy are adjusted, thereby enabling the alloy to obtain a low coefficient of thermal expansion along the two-dimensional direction. The preparation method is carried out in the following steps:

[0095] (1) Control the alloy composition ratio to ensure that the atomic percentages are: Nb 14.5%, Zr 2.42%, Sn 3.87%, O 0.43%, with the balance being Ti;

[0096] (2) Press the alloy electrode and perform vacuum melting;

[0097] (3) Forging is carried out at 800℃ with a deformation of 25%, and then cooled to room temperature at 15℃ / min.

[0098] (4) Figure 1 As shown, the rolling temperature and rolling direction are controlled, and rolling is carried out at 400℃ along the predetermined direction with a deformation of 20%. After rolling, cooling is performed with a cooling rate of 20℃ / minute.

[0099] (5) Figure 1 As shown, the rolling temperature and rolling direction are controlled, and rolling is carried out at 500℃ along a direction at 90 degrees to the predetermined direction, with a deformation of 40%. After rolling, cooling is performed, and the cooling rate is controlled at 25℃ / minute.

[0100] (6) Figure 1 As shown, the rolling temperature and rolling direction are controlled, and rolling is performed at 30°C along the predetermined direction in step (4), with a rolling deformation of 20%.

[0101] (7) Figure 1 As shown, the rolling temperature and rolling direction are controlled, and the rolling process is carried out at 20°C in a direction of 90 degrees along the predetermined direction in step (6), with a rolling deformation of 15%.

[0102] (8) Figure 1 As shown, the rolling temperature and rolling direction are controlled, and the rolling process is carried out at 20°C in a direction of 30 degrees along the predetermined direction in step (6), with a rolling deformation of 30%.

[0103] (9) such as Figure 1 As shown, the rolling temperature and rolling direction are controlled, and the rolling process is carried out at 20°C in a 60-degree direction along the predetermined direction in step (6), with a rolling deformation of 30% and the thickness of the titanium alloy plate controlled to be 5mm.

[0104] (10) The titanium alloy obtained in step (9) is subjected to heating-holding-cooling treatment. The heating rate is 450℃ / min, the holding temperature is 350℃, the holding time is 4 hours, and the cooling rate is 20℃ / min.

[0105] (11) The titanium alloy obtained in step (10) is subjected to a heating-cooling treatment. The heating rate is 5℃ / min, the temperature is raised to 250℃, and the cooling rate is 5℃ / min.

[0106] (12) A two-dimensional zero-expansion titanium alloy plate with a thickness of 4.5 mm was obtained, which was composed of an orthogonal α″ phase and a body-centered cubic β phase. In the temperature range of -200 to 300℃, the thermal expansion coefficient of the alloy was less than 2 ppm / ℃ along the rolling direction, less than 2 ppm / ℃ along the transverse direction, and less than 3 ppm / ℃ in any direction between the rolling direction and the transverse direction.

[0107] Comparative Example 1

[0108] Pure titanium, pure niobium, and pure tantalum are blended in a specific ratio, with Nb comprising 25%–29% by mass, Ta comprising 14%–20% by mass, and the remainder being Ti. The ingot is smelted and cast using vacuum arc melting technology. The ingot undergoes high-temperature homogenization diffusion heat treatment to eliminate elemental segregation. It is then hot-forged, annealed, and quenched. Finally, it is cold-rolled with a deformation of 40%–50%. The titanium alloy sheet obtained using this technique does not possess two-dimensional zero-expansion properties.

[0109] Comparative Example 2

[0110] The process involves five melting stages using vacuum consumable electrode arc melting technology. The ingot undergoes a 24-hour homogenization diffusion treatment at 1050°C to eliminate elemental segregation. The ingot is then hot-forged into a square billet at 900°C. The billet is then hot-rolled into a thick plate at 650°C. The thick plate undergoes solution treatment and quenching. The solution treatment is performed at 900°C for 15 minutes using water as the quenching medium. The quenched thick plate is then cold-rolled at room temperature with a deformation of 40%. Finally, the cold-rolled plate undergoes a short-time heat treatment at 350°C for 40 minutes. The titanium alloy sheet obtained using this technique does not possess two-dimensional zero-expansion properties.

[0111] Comparative Example 3

[0112] Similar to Example 1, the difference lies in the following: the titanium alloy material obtained after hot forging is hot-rolled at 1123K into a block alloy; the obtained block alloy is then encapsulated in a quartz tube for heat treatment at 1123K for 24 hours, followed by air cooling; the cooled block alloy is then cold-rolled at room temperature in the same direction with an 8% reduction. The titanium alloy obtained according to this technical solution only possesses unidirectional zero expansion properties and does not have two-dimensional zero expansion characteristics.

Claims

1. A two-dimensional zero-expansion titanium alloy sheet, characterized in that, The titanium alloy sheet is composed of titanium, niobium, zirconium, tin and oxygen atoms. The constituent phases are composed of orthorhombic α″ phase and body-centered cubic β phase. In the temperature range of -200 to 300℃, the coefficient of thermal expansion of the titanium alloy sheet is less than 4ppm / ℃ along the rolling direction, less than 4ppm / ℃ along the transverse direction, and less than 4ppm / ℃ in any direction between the rolling direction and the transverse direction.

2. The two-dimensional zero-expansion titanium alloy sheet according to claim 1, characterized in that, The composition of titanium alloys by atomic percentage is as follows: Nb 12-17%, Zr 2-3%, Sn 3-5%, O 0.4-0.5%, with the balance being Ti.

3. A method for preparing a two-dimensional zero-expansion titanium alloy sheet according to any one of claims 1 to 2, characterized in that, By limiting the atomic ratios of Nb, Zr, and Sn and controlling the rolling process, the phase stability, lattice mismatch strain, and volume fraction of the precipitated phase and the parent phase in the alloy can be adjusted, thereby enabling the alloy to obtain a low coefficient of thermal expansion along the two-dimensional direction.

4. The method for preparing a two-dimensional zero-expansion titanium alloy sheet according to claim 3, characterized in that, Follow these steps in sequence: (1) Control the alloy composition ratio so that the atomic percentages satisfy: Nb 12~17%, Zr 2~3%, Sn 3~5%, O 0.4~0.5%, with the balance being Ti, and Nb:Zr:Sn=(14.9~15.1):(2.4~2.6):(3.9~4.1); (2) Press the alloy electrode and perform vacuum melting; (3) Forging is carried out in the range of 650 to 1200℃, the deformation is controlled at 10 to 50%, and then cooled to room temperature at a cooling rate of 10 to 30℃ / minute. (4) Control the rolling temperature and rolling direction, and perform rolling processing in the predetermined direction within the range of 300 to 650℃, with a deformation of 10 to 50%. After rolling, cool the material and control the cooling rate to 10 to 25℃ / minute. (5) Control the rolling temperature and rolling direction, and perform rolling in the range of 300 to 550°C along a direction at 90 degrees to the predetermined direction, with a deformation of 10 to 50%. After rolling, cool the material and control the cooling rate to 10 to 25°C / minute. (6) Control the rolling temperature and rolling direction, and perform rolling processing in the predetermined direction in step (4) within the range of 10 to 50°C, with a rolling deformation of 5 to 30%. (7) Control the rolling temperature and rolling direction, and perform rolling processing in the range of 10 to 50°C along the predetermined direction in step (6) at a 90-degree angle, with a rolling deformation of 5 to 30%. (8) Control the rolling temperature and rolling direction, and perform rolling processing in the range of 10 to 50°C along the predetermined direction in step (6) at a 30-degree angle, with a rolling deformation of 5 to 30%. (9) Control the rolling temperature and rolling direction, and perform rolling processing in the range of 10 to 50°C along the predetermined direction in step (6) at a 60-degree angle, with a rolling deformation of 5 to 30%, and control the thickness of the titanium alloy plate to be 1 to 5 mm. (10) The titanium alloy obtained in step (9) is subjected to heating-holding-cooling treatment. The heating rate is 50-500℃ / min, the holding temperature is 300-500℃, the holding time is 0.5-4 hours, and the cooling rate is 5-40℃ / min. (11) The titanium alloy obtained in step (10) is subjected to a heating-cooling treatment. The heating rate is 3 to 20 °C / min, the temperature is raised to 250 to 400 °C, and the cooling rate is 3 to 30 °C / min. (12) A two-dimensional zero-expansion titanium alloy plate with a thickness of 1-5 mm was obtained.

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