A low-magnetic high-strength titanium alloy and a preparation method thereof

Abstract

This application relates to the field of titanium alloy technology, specifically to a low-magnetic-susceptibility high-strength titanium alloy and its preparation method. The low-magnetic-susceptibility titanium alloy, by elemental mass percentage, comprises Ag: 0.5% to 13%, β-stabilizing element: 5.0% to 30%, wherein the β-stabilizing element includes at least one of Mo and Ta, with the balance being Ti and unavoidable impurities. The phase composition of the low-magnetic-susceptibility high-strength titanium alloy includes a β-Ti matrix phase and Ti2Ag particle phase, martensitic phase, and ω phase dispersed in the matrix phase. The β-stabilizing element and some Ag are dissolved in the β-Ti matrix. This application, by selecting specific amounts of Ag and β-stabilizing elements to form a specific phase composition, achieves a synergistic effect between the elements and phases, resulting in a low-magnetic-susceptibility high-strength titanium alloy with low magnetic susceptibility, high strength, high antibacterial rate, high corrosion resistance, and good plasticity.

Description

Technical Field

[0001] This application relates to the field of titanium alloys, specifically to a high-strength titanium alloy with low magnetic susceptibility and its preparation method. Background Technology

[0002] Titanium alloys are widely used in medical, aerospace, and other fields due to their low density, high specific strength, excellent corrosion resistance, and biocompatibility. However, traditional titanium alloys (such as Ti-6Al-4V and Ti-3Al-2.5V) have the following drawbacks: high magnetic susceptibility; currently, the mass magnetic susceptibility of pure titanium is 3.2 × 10⁻⁶. -6 cm 3 The mass magnetic susceptibility of commercially available Ti-6Al-4V alloy containing elements such as Al, V, and Fe is approximately 3.85 × 10⁻⁶ g. -6 cm 3 / g, easily produces a paramagnetic response, interfering with precision magnetic detection such as MRI / CT.

[0003] While maintaining the good biocompatibility, strength, and corrosion resistance of titanium alloys, reducing the magnetic susceptibility of the alloy will greatly improve its adaptability. Researchers are constantly trying various alloying methods to reduce the magnetic susceptibility of alloys. For example, the literature "Research on the Performance of Low Magnetic Susceptibility Titanium-Zirconium-Niobium-Tin Alloys" published in World Nonferrous Metals, June 2025, p27, reports on (TiZr) 85 Nb 10 The magnetic susceptibility of Sn5 alloy is 2.369 x 10⁻⁶. -6 cm 3 / g, (TiZr) 82 Nb 10 The magnetic susceptibility of Sn8 alloy is 2.486 x 10⁻⁶. -6 cm 3 / g, (TiZr) 80 Nb 10 Sn 10 The alloy has a magnetic susceptibility of 2.353 x 10⁻⁶. -6 cm 3 / g; Wang Fei's master's thesis at Nanjing University of Aeronautics and Astronautics, "Research on Titanium Alloys for Low-Nuclear-Magnetic-Induced Dental Implants," describes the Ti-20Zr-20Sn alloy he developed, which has a mass magnetic susceptibility of 2.94 × 10⁻⁶ g. -6 cm 3 The mass magnetic susceptibility of the Ti-20Zr-10Sn-10Mo alloy is 2.90 × 10⁻⁶ g. -6 cm 3 / g. Although the magnetic susceptibility of these alloys is lower than that of pure titanium and Ti-6Al-4V alloys, it is still relatively high. At the same time, titanium alloy materials, while having low magnetic susceptibility, also need to have high strength to meet the requirements of processing and use.

[0004] Therefore, it is necessary to develop new high-strength titanium alloy materials with lower mass magnetic susceptibility to meet practical requirements. Summary of the Invention

[0005] In view of this, the purpose of this application is to propose a high-strength titanium alloy with low magnetic susceptibility and its preparation method, so as to solve the problem of high magnetic susceptibility of existing titanium alloys.

[0006] Based on the above objectives, the first aspect of this application provides a high-strength titanium alloy with low magnetic susceptibility, comprising, by elemental mass percentage, 0.5% to 13% Ag, 5.0% to 30% β-stabilizing element, wherein the β-stabilizing element includes at least one of Mo and Ta, and the balance is Ti and unavoidable impurities; the phase composition of the high-strength titanium alloy with low magnetic susceptibility includes a β-Ti matrix phase and Ti2Ag particle phase, martensitic phase and ω phase dispersed in the matrix phase, wherein the β-stabilizing element and part of Ag are dissolved in the β-Ti matrix.

[0007] Preferably, the β-stabilizing element further includes Hf.

[0008] Preferably, the volume fraction of the Ti2Ag particle phase is ≤8%, and the size of the Ti2Ag particles is ≤50 nm.

[0009] Preferably, the mass magnetic susceptibility of the low-magnetic-susceptibility high-strength titanium alloy at room temperature is ≤1.2×10⁻⁶. -6 cm³ / g.

[0010] Preferably, the low magnetic susceptibility high-strength titanium alloy has a tensile strength ≥930MPa, a yield strength ≥860MPa, and an elongation ≥10% at room temperature.

[0011] Preferably, the mass percentage of Ag is 3% to 10%.

[0012] Preferably, the mass percentage of the β-stabilizing element is 10% to 25%.

[0013] The second aspect of this application provides a method for preparing a high-strength titanium alloy with low magnetic susceptibility. The high-strength titanium alloy with low magnetic susceptibility is the aforementioned high-strength titanium alloy with low magnetic susceptibility. The preparation method includes the following steps: Smelting: Prepare Ti, Ag and β stabilizing element raw materials according to element mass percentage, mix them evenly and press the electrode, and then perform vacuum arc melting on the electrode to obtain an ingot. The ingots are subjected to homogenization heat treatment, hot forging, hot rolling, solution treatment, cold deformation and aging treatment in sequence. Solution treatment involves heating the hot-rolled forging to 850-950℃ and holding it for 1 to 3 hours. After holding, the forging is quenched in ice water at 0℃ to 5℃ to form a mixed structure of β phase and martensite.

[0014] Preferably, the temperature of cold deformation is ≤200℃.

[0015] Preferably, the aging treatment temperature is 300℃ to 550℃, and the holding time is 2h to 6h.

[0016] The beneficial effects of this application are: This application discloses a high-strength titanium alloy with low magnetic susceptibility, comprising, by element mass percentage, 0.5%-13% Ag and 5.0%-30% β-stabilizing elements, wherein the β-stabilizing elements include one or more of Mo, Ta, and Hf, with the balance being Ti and unavoidable impurities; the phase composition of the high-strength titanium alloy with low magnetic susceptibility includes a β-Ti matrix phase and Ti2Ag particle phase, martensite phase, and ω phase dispersed in the matrix phase, wherein the β-stabilizing elements and part of Ag are dissolved in the β-Ti matrix.

[0017] This application selects Ag and β stabilizing elements as alloying elements. By adjusting the mass percentage of each alloying element and the phase composition of the titanium alloy, the phases work synergistically to give the titanium alloy excellent properties such as low magnetic susceptibility, high strength, high antibacterial rate and high corrosion resistance.

[0018] This application discloses a high-strength titanium alloy with low magnetic susceptibility, exhibiting a significantly lower magnetic susceptibility than conventional titanium alloys: a mass magnetic susceptibility at room temperature ≤ 1.2 × 10⁻⁶. -6 cm³ / g, NMR compatible with no artifacts.

[0019] This application discloses a high-strength titanium alloy with low magnetic susceptibility, which, while maintaining low magnetic susceptibility, possesses excellent mechanical and processing properties: tensile strength ≥930 MPa, yield strength ≥860 MPa, and elongation ≥10%.

[0020] This application discloses a low magnetic susceptibility high-strength titanium alloy containing nanoscale Ti2Ag particles. It does not require additional antibacterial coatings and has no risk of coating peeling. The alloy itself has excellent antibacterial properties with an antibacterial rate of ≥99%, making it suitable for medical implants and other applications with strict antibacterial requirements.

[0021] This application discloses a high-strength titanium alloy with low magnetic susceptibility, good corrosion resistance, and no toxic or allergenic elements, making it suitable for human implantation and use in harsh environments.

[0022] This application also provides a method for preparing a high-strength titanium alloy with low magnetic susceptibility. Through melting, homogenization heat treatment, hot forging, hot rolling, solution treatment, cold deformation, and aging treatment, a titanium alloy phase structure can be obtained, comprising a β-Ti matrix phase and Ti2Ag particles dispersed in the matrix phase, a martensitic phase, and an ω phase, as well as β-stabilizing elements and some Ag dissolved in the β-Ti matrix. The process exhibits good consistency and is suitable for large-scale industrial production. Attached Figure Description

[0023] Figure 1 Metallographic diagram of a high-strength titanium alloy with low magnetic susceptibility provided for this application. Detailed Implementation

[0024] As analyzed in the background section of this application, existing titanium alloys have high magnetic susceptibility, which easily leads to paramagnetic responses in precision magnetic detection such as MRI and CT scans, interfering with the detection results. The mass magnetic susceptibility of pure titanium is 3.2 × 10⁻⁶. -6 cm 3 The mass magnetic susceptibility of commercially available Ti-6Al-4V alloy containing elements such as Al, V, and Fe is approximately 3.85 × 10⁻⁶ g. -6 cm 3 / g, existing research shows (TiZr) 85 Nb 10 The magnetic susceptibility of Sn5 alloy is 2.369 x 10⁻⁶. -6 cm 3 / g, (TiZr) 82 Nb 10 The magnetic susceptibility of Sn8 alloy is 2.486 x 10⁻⁶. -6 cm 3 / g, (TiZr) 80 Nb 10 Sn 10 The alloy has a magnetic susceptibility of 2.353 x 10⁻⁶. -6 cm 3 The mass magnetic susceptibility of Ti-20Zr-20Sn alloy is 2.94 × 10⁻⁶ g. -6 cm 3 The mass magnetic susceptibility of the Ti-20Zr-10Sn-10Mo alloy is 2.90 × 10⁻⁶ g. -6 cm 3 / g, still relatively high.

[0025] In view of the above problems, this application provides a low magnetic susceptibility high-strength titanium alloy and its preparation method in one or more of the following embodiments, which maintains excellent mechanical properties while significantly reducing magnetic susceptibility, in order to solve the application limitations of titanium alloy products in technical fields such as precision magnetic detection, magnetic precision measurement, and electronic optical equipment that have more stringent requirements for magnetic cleanliness.

[0026] In a typical embodiment of this application, a high-strength titanium alloy with low magnetic susceptibility is provided, comprising, by elemental mass percentage, 0.5% to 13% Ag, 5.0% to 30% β-stabilizing element, wherein the β-stabilizing element includes at least one of Mo and Ta, and the balance is Ti and unavoidable impurities; the phase composition of the high-strength titanium alloy with low magnetic susceptibility includes a β-Ti matrix phase and Ti2Ag particle phase, martensitic phase and ω phase dispersed in the matrix phase, wherein the β-stabilizing element and part of Ag are dissolved in the β-Ti matrix.

[0027] This application achieves the effects of low magnetic susceptibility, high strength, high antibacterial rate, and high corrosion resistance by selecting alloying elements and controlling the phases in the alloy. 1) Selection of alloying elements The first alloying element selected in this application is Ag, which is a diamagnetic metal with a mass magnetic susceptibility of -0.18 × 10⁻⁶ at room temperature. -6 cm 3 / g, whose negative magnetic susceptibility can counteract the paramagnetism of the titanium matrix.

[0028] The titanium alloy provided in this application contains Ag at a mass percentage ranging from 0.5% to 13%. For example, the mass percentage of Ag can be 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, or 13%. When the mass percentage of Ag is less than 0.5%, it is difficult to precipitate Ti2Ag particles, resulting in a titanium alloy with high magnetic susceptibility and low strength. When the mass percentage of Ag is greater than 13%, the formed Ti2Ag particles are too large, making it difficult to reduce the magnetic susceptibility of the titanium alloy and causing a decrease in strength.

[0029] The second alloying element is a β-stabilizing element, including one or more of Mo and Ta. Mo and Ta are weakly paramagnetic elements, and their mass magnetic susceptibility at room temperature is 0.93 × 10⁻⁶. -6 cm 3 / g, 0.84×10 -6 cm 3 / g, all significantly lower than the mass magnetic susceptibility of pure Ti (3.2×10). -6 cm 3 / g, when dissolved in the titanium matrix, can reduce the overall magnetic susceptibility of the titanium alloy to zero through a linear dilution effect.

[0030] The β-stabilizing element in the titanium alloy provided in this application can be pure Mo, pure Ta, or a mixture of Mo and Ta. Both Mo and Ta are β-stabilizing elements with different β-phase stabilizing abilities. They can retain unstable β-Ti to room temperature and maintain its stability, thereby increasing the strength and toughness of the titanium alloy. In addition, the addition of Ta can further refine the β-Ti grains.

[0031] The titanium alloys provided in this application contain 5.0%-30% by mass of β-stabilizing elements. For example, the mass percentage of β-stabilizing elements can be 5.0%, 8.0%, 10%, 12%, 15%, 20%, 22%, 25%, 28%, or 30%. When the mass percentage of β-stabilizing elements is less than 5.0%, it is difficult to obtain the β phase in the titanium alloy, and the magnetic susceptibility and strength are difficult to meet the requirements. When the mass percentage of β-stabilizing elements is greater than 30%, the grains tend to become coarser, making it difficult to obtain the required phase structure in subsequent processing, and the magnetic susceptibility, strength, and plasticity are difficult to meet the requirements.

[0032] 2) Phase structure of the alloy: The properties of each phase and its contribution to the performance of the titanium alloy are described below: β phase: The magnetic susceptibility of each phase in titanium alloy from high to low is: β-Ti > α'-Ti > α'' - Ti > ω phase. Among them, the β-Ti matrix contains all the β-stabilizing elements and some Ag in solid solution, and has a low magnetic susceptibility. The β-Ti matrix has good plasticity and is easy to cold work. At the same time, the β-stabilizing elements can stabilize the β phase at room temperature.

[0033] Ag dissolved in the β phase occupies some lattice sites, resulting in a relatively lower concentration of β-stabilizing elements in the β-Ti matrix. This leads to an increase in the martensitic transformation temperature and makes the β→α' transformation more likely to occur during rapid cooling. Furthermore, the distribution of Ag in the β-Ti matrix is ​​not absolutely uniform, resulting in a corresponding decrease in the electron concentration of β-stabilizing elements in microregions with higher Ag concentrations, thereby inducing the nucleation of the ω phase.

[0034] Martensite phase: including α'-Ti and α''-Ti, formed by the precipitation of β phase during rapid cooling and aging. Compared with β titanium matrix, martensite phase has lower magnetic susceptibility, which can further reduce the overall magnetic susceptibility of titanium alloy. In addition, martensite phase has high strength and high hardness, which can improve the strength of titanium alloy. ω phase: formed through martensitic phase transformation during aging, it has a lower magnetic susceptibility than the martensitic phase, and the ω phase can also significantly improve the strength of titanium alloys. Ti2Ag granular phase: Due to the diamagnetism of Ag, the Ti2Ag granular phase itself has a low magnetic susceptibility. The lattice mismatch between the Ti2Ag granular phase and the β-Ti matrix generates a strain field around the particles. This field, by altering the matrix lattice symmetry and scattering conduction electrons, suppresses the magnetic response of the localized d-electron magnetic moments introduced by the solid-solution β-stabilizing elements, thereby reducing the magnetic susceptibility of the matrix. Simultaneously, the Fermi level difference at the interface between the Ti2Ag granular phase and the β-Ti matrix leads to charge redistribution near the interface, further weakening the paramagnetism of the matrix. In addition, the stress field generated by the Ti2Ag granular phase can promote the precipitation of martensite and ω phases, reducing the volume fraction of the paramagnetic β phase. The synergistic effect of these effects significantly reduces the overall magnetic susceptibility of the alloy. The uniformly dispersed Ti2Ag granular phase in the β-Ti matrix can exert a second-phase dispersion strengthening effect, pinning and hindering dislocation movement, thereby improving the yield strength and rheological stress of the titanium alloy.

[0035] In some embodiments, the β-stabilizing element also includes Hf.

[0036] The magnetic susceptibility of Hf is 0.45 × 10⁻⁶. -6 cm 3 / g, when dissolved in the titanium matrix, can reduce the overall magnetic susceptibility of the titanium alloy to zero through a linear dilution effect. Hf can play multiple roles in titanium alloys, including assisting in stabilizing the β phase, solid solution strengthening, and refining grains. In this application, the addition of Hf can promote the precipitation of fine, dispersed Ti2Ag particles, thereby helping to reduce the magnetic susceptibility of the titanium alloy.

[0037] In some embodiments, the volume fraction of the Ti2Ag particle phase is ≤8%, and the size of the Ti2Ag particles is ≤50 nm.

[0038] Ti₂Ag particles are relatively hard and brittle intermetallic compounds. Controlling their volume fraction to below 8% can help titanium alloys maintain good plasticity and toughness. When the size is ≤50 nm, Ti₂Ag particles generate a huge specific surface area and phase interface, which scatters magnetic field lines and dissipates their energy. At the same time, the pinning effect generated by a large number of fine Ti₂Ag particles can also hinder the movement of magnetic domains, further reducing the magnetization.

[0039] In some embodiments, the mass magnetic susceptibility of the low-magnetic-susceptibility high-strength titanium alloy at room temperature is ≤1.2×10⁻⁶. -6 cm³ / g.

[0040] In some embodiments, the low magnetic susceptibility high-strength titanium alloy has a tensile strength ≥930 MPa, a yield strength ≥860 MPa, and an elongation ≥10% at room temperature.

[0041] In some embodiments, the mass percentage of Ag is 3% to 10%.

[0042] In some embodiments, the mass percentage of the β-stabilizing element is 10% to 25%.

[0043] Optionally, the mass percentage of impurity elements meets the following conditions: Fe≤0.4%, C≤0.08%, N≤0.05%, O≤0.40%.

[0044] In the second typical embodiment of this application, such as Figure 1 This application provides a method for preparing a high-strength titanium alloy with low magnetic susceptibility. The high-strength titanium alloy with low magnetic susceptibility is the aforementioned high-strength titanium alloy with low magnetic susceptibility. The preparation method includes the following steps: Smelting: Prepare Ti, Ag and β stabilizing element raw materials according to element mass percentage, mix them evenly and press the electrode, and then perform vacuum arc melting on the electrode to obtain an ingot. The ingots are subjected to homogenization heat treatment, hot forging, hot rolling, solution treatment, cold deformation and aging treatment in sequence. Solution treatment involves heating the hot-rolled forging to 850°C to 950°C and holding it for 1-3 hours. After holding, the forging is quenched in ice water at 0°C to 5°C to form a mixed structure of β phase and martensite.

[0045] The solution treatment and holding step allows Ag and β-stabilizing elements to completely dissolve in the matrix, stabilizing the titanium alloy matrix in the β phase, preventing the formation of the α phase, and precipitating some martensitic phase, resulting in a mixed β-phase and martensite microstructure. Quenching the forging in ice water at 0°C to 5°C with rapid cooling can suppress the formation of the α-phase and coarse Ti-Ag compounds. Quenching temperatures below 0°C with excessively rapid cooling can easily lead to cracking of the forging.

[0046] Optionally, before pressing the mixed raw materials into electrodes, the oxide scale and oil stains on the surface of each raw material are removed, and the materials are vacuum dried at 120°C for 2 hours.

[0047] Optionally, the vacuum degree during vacuum arc melting is ≤5×10 -3 Pa, the number of smelting times is more than 2.

[0048] Optionally, the homogenization heat treatment involves placing the smelted ingot in a vacuum furnace at a vacuum degree ≤1×10⁻⁶. -3 Hold at Pa for 4-10 hours, with a holding temperature range of 1050℃ to 1150℃. After holding, furnace cool to 500℃ and then air cool. Homogenization heat treatment can make β-stabilizing elements and Ag elements diffuse evenly, eliminate compositional segregation, eliminate coarse as-cast structures, and make the grains equiaxed, which is beneficial for subsequent billet making and forging.

[0049] Optionally, hot forging involves heating the homogenized ingot to 900℃ to 1150℃ and holding it for 1-2 hours. After holding, multi-directional forging is performed with a deformation amount ≥60% and a final forging temperature ≥850℃. The forged billet is then air-cooled to obtain a forged billet. Hot forging can further break down the coarse structure in the as-cast state and increase the density of the ingot material. Hot forging is controlled to perform deformation treatment in the β phase region, where the ingot has good plasticity and it is easy to achieve a large deformation amount.

[0050] Optionally, hot rolling involves heating the hot-forged billet to 900°C to 1050°C and then rolling it into a forging.

[0051] In some embodiments, the cold deformation temperature is ≤200°C. Cold deformation is used to process forgings into desired shapes, such as bars, plates, etc. 200°C is below the recrystallization temperature of titanium alloys. Cold deformation at this temperature can significantly refine the grains of titanium alloys, achieving a fine-grain strengthening effect and increasing the strength of titanium alloys. In addition, the refined grains can also provide nucleation sites such as dislocations and grain boundaries for the subsequent formation of nano-Ti2Ag, promoting the formation of Ti2Ag granular phases.

[0052] In some embodiments, the aging treatment temperature is 300°C to 550°C, and the holding time is 2 hours to 6 hours. Aging involves heating the cold-deformed titanium alloy material to a certain temperature and holding it there, so that martensite phase, ω phase, and uniformly dispersed nano-Ti2Ag particles continue to precipitate in the titanium alloy material, forming a multiphase coexistence structure in the titanium alloy material, which synergistically reduces the magnetic susceptibility, improves strength and plasticity, and achieves a balance between strength and plasticity.

[0053] The aging temperature affects the precipitation behavior of the ω phase and Ti2Ag granular phase. When the temperature is below 300℃, the ω phase and Ti2Ag granular phase cannot precipitate; when the temperature is above 550℃, the ω phase precipitates and then disappears, and the Ti2Ag granular phase grows to form coarse grains, thus failing to exert the effects of dispersion strengthening and reducing magnetic susceptibility.

[0054] The aging time affects the quantity and size of the ω phase and Ti2Ag granular phase. When the aging time is less than 2 hours, the quantity of ω phase and Ti2Ag granular phase is small, or even unable to precipitate. When the aging time is longer than 6 hours, the ω phase content is too high, leading to a decrease in the plasticity of the titanium alloy material. The volume fraction of Ti2Ag granular phase increases significantly, and the particles are coarse, which reduces the plasticity and toughness of the titanium alloy material and fails to achieve the effect of reducing magnetic susceptibility.

[0055] Figure 1The figure shows the effect of different aging temperatures and times on the quantity and size of Ti2Ag particles. The bright white particles represent nanoscale Ti2Ag particles, the gray area represents the β-Ti matrix, and the martensitic and ω phases are uniformly dispersed in the β-Ti matrix. The β-stabilizing element solid solution is uniformly distributed, with no obvious segregation or continuous grain boundary precipitates. This visually demonstrates the change in the size and morphology of the Ti2Ag phase in the alloy with aging temperature and time, indicating that the microstructure homogeneity and the distribution of each phase are controllable, and that the β-stabilizing element can effectively regulate the stability of the β phase.

[0056] The embodiments of this application will be further described below with reference to several examples. However, the embodiments of this application are not limited to the specific embodiments described below. Appropriate modifications can be made within the scope of protection.

[0057] Example 1 This embodiment provides a high-strength titanium alloy with low magnetic susceptibility, comprising, by element mass percentage: Ag: 10%, β-stabilizing element Mo: 10%, impurity elements Fe: 0.3%, C: 0.05%, N: 0.05%, O: 0.2%, with the balance being Ti; The phase composition of the low magnetic susceptibility high-strength titanium alloy includes a β-Ti matrix phase and Ti2Ag particles, martensite, and ω phase dispersed in the matrix phase. β-stabilizing elements and some Ag are dissolved in the β-Ti matrix.

[0058] The preparation method of the above-mentioned low magnetic susceptibility high-strength titanium alloy includes the following steps: Smelting: Prepare Ti, Ag, and β-stabilizing element raw materials according to elemental mass percentages, mix them evenly, and then press the electrode. The electrode is then subjected to a vacuum degree ≤ 5 × 10⁻⁶. -3 Vacuum arc melting was performed three times under Pa conditions, with each time the ingot was reversed by 180 degrees to obtain a casting. Homogenization heat treatment: Place the ingot in a vacuum furnace and heat it at a vacuum degree ≤1×10⁻⁶. -3 Hold at 1050℃ for 10 hours, then air cool after the furnace is cooled to 500℃. Hot forging: The ingot after homogenization heat treatment is heated to 900℃, held for 1 hour and then multi-directional forging is carried out with a deformation of 60% and a final forging temperature of ≥850℃. After forging, the forging billet is obtained by air cooling. Hot rolling: The above forging billet is heated to 900℃ and rolled into a forging, which is an 8 mm bar. Solution treatment: Heat the above forgings to 850°C, hold for 3 hours, and then quench in ice water at 0°C to 5°C; Cold deformation: The quenched forging is heated and cold deformed at a temperature of ≤200℃ to form a bar with a diameter of 6 mm; Aging: The above 6 mm rods are heated to 300℃ and held for 6 hours to obtain high-strength titanium alloy rods with low magnetic susceptibility.

[0059] The magnetic properties, mechanical properties, antibacterial rate, and corrosion resistance of the above-mentioned bars were tested respectively. The test results are as follows: Mass magnetic susceptibility: 1.1 × 10⁻⁶ -6 cm 3 / g; MRI compatibility: No artifacts; Tensile strength: 1050 MPa; Yield strength: 930 MPa; Elongation: 11%; Antibacterial rate: 99.5%; Self-corrosion current density: 2.5 × 10 -8 A / cm 2 .

[0060] Example 2 The difference from Example 1 is that, by mass percentage, it includes Ag: 3.0% and β-stabilizing element Ta: 25%.

[0061] The homogenization heat treatment temperature was 1150℃, and the holding time was 4 hours. The hot forging temperature is 1150℃; The hot rolling temperature is 1050℃; The solution temperature was 950℃, and the holding time was 1 hour. The aging temperature is 550℃, and the holding time is 6 hours.

[0062] The performance test results of the sample in this embodiment are as follows: Mass magnetic susceptibility: 1.2 × 10⁻⁶ -6 cm 3 / g; MRI compatibility: No artifacts; Tensile strength: 930 MPa; Yield strength: 860 MPa; Elongation: 20%; Antibacterial rate: 99.2%; Self-corrosion current density: 2.7 × 10 -8 A / cm 2 .

[0063] Example 3 The difference from Example 1 is that, by mass percentage, it includes Ag: 13.0%, β-stabilizing element Mo: 2.5%, and Hf: 2.5%.

[0064] The homogenization heat treatment temperature was 1100℃, and the holding time was 6 hours. The hot forging temperature is 1050℃, and the deformation is 65%. The hot rolling temperature is 950℃; The solution temperature is 900℃, and the holding time is 2 hours. The aging temperature is 450℃, and the holding time is 4 hours.

[0065] The performance test results of the sample in this embodiment are as follows: Mass magnetic susceptibility: 1.0 × 10⁻⁶ -6 cm 3 / g; MRI compatibility: No artifacts; Tensile strength: 980 MPa; Yield strength: 880 MPa; Elongation: 18%; Antibacterial rate: 99.7%; Self-corrosion current density: 2.1 × 10 -8 A / cm 2 .

[0066] Example 4 The difference from Example 1 is that, by mass percentage, it includes Ag: 0.5%, β-stabilizing element Mo: 12%, Ta: 13%, and Hf: 5%.

[0067] The homogenization heat treatment temperature is 1150℃; The hot forging temperature is 1150℃, and the deformation is 70%. The hot rolling temperature is 950℃; The solution temperature was 950℃, and the holding time was 3 hours. The aging temperature is 450℃, and the holding time is 4 hours.

[0068] The performance test results of the sample in this embodiment are as follows: Mass magnetic susceptibility: 1.1 × 10⁻⁶ -6 cm 3 / g; MRI compatibility: No artifacts; Tensile strength: 950 MPa; Yield strength: 860 MPa; Elongation: 25%; Antibacterial rate: 99.8%; Self-corrosion current density: 2.5 × 10 -8 A / cm 2 .

[0069] Example 5 The difference from Example 1 is that, by mass percentage, it includes Ag: 7% and β-stabilizing element Mo: 18%.

[0070] The homogenization heat treatment temperature was 1150℃, and the holding time was 6 hours. The hot forging temperature is 1150℃, and the deformation is 65%. The hot rolling temperature is 1050℃; The solution temperature was 950℃, and the holding time was 1 hour. The aging temperature is 550℃, and the holding time is 6 hours.

[0071] The performance test results of the sample in this embodiment are as follows: Mass magnetic susceptibility: 1.2 × 10⁻⁶ -6 cm 3 / g; MRI compatibility: No artifacts; Tensile strength: 930 MPa; Yield strength: 860 MPa; Elongation: 20%; Antibacterial rate: 99.2%; Self-corrosion current density: 2.7 × 10 -8 A / cm 2 .

[0072] Comparative Example 1 Commercially available Ti-6Al-4V titanium alloy was purchased, and samples were taken to test its magnetic properties, mechanical properties, antibacterial rate, and corrosion resistance. The test results are as follows: Mass magnetic susceptibility: 3.3 × 10⁻⁶ -6 cm 3 / g; MRI compatibility: artifacts are present; Tensile strength: 950 MPa; Yield strength: 880 MPa; Elongation: 14%; Antibacterial rate: None; Self-corrosion current density: 6.0 × 10 -8 A / cm 2 .

[0073] Comparative Example 2 The difference from Example 1 is the absence of β-stabilizing elements. The titanium alloy matrix cannot maintain a stable β phase.

[0074] The performance test results of this comparative example sample are as follows: Mass magnetic susceptibility: 2.5 × 10⁻⁶ -6 cm 3 / g; MRI compatibility: artifacts are present; Tensile strength: 780 MPa; Yield strength: 560 MPa; Elongation: 20%; Antibacterial rate: 98%; Self-corrosion current density: 7.2 × 10 -8 A / cm 2 .

[0075] Comparative Example 3 The difference from Example 1 is that, by mass percentage, it includes Ag: 13.0% and the β-stabilizing element Mo: 4.5%. It is difficult for a titanium alloy matrix to form a stable β-Ti matrix phase.

[0076] The performance test results of this comparative example sample are as follows: Mass magnetic susceptibility: 2.3 × 10⁻⁶ -6 cm 3 / g; MRI compatibility: artifacts are present; Tensile strength: 600 MPa; Yield strength: 450 MPa; Elongation: 21%; Antibacterial rate: 98%; Self-corrosion current density: 5.6 × 10 -8 A / cm 2 .

[0077] Comparative Example 4 The difference from Example 1 is that, by mass percentage, it includes Ag: 0.5% and the β-stabilizing element Mo: 4.5%. It is difficult for a titanium alloy matrix to form a stable β-Ti matrix phase.

[0078] The performance test results of this comparative example sample are as follows: Mass magnetic susceptibility: 2.8 × 10⁻⁶ -6 cm 3 / g; MRI compatibility: artifacts are present; Tensile strength: 560 MPa; Yield strength: 400 MPa; Elongation: 35%; Antibacterial rate: 10%; Self-corrosion current density: 6.2 × 10 -8 A / cm 2 .

[0079] Comparative Example 5 The difference from Example 1 is that, by mass percentage, it includes Ag: 13%, β-stabilizing element Mo: 12%, Ta: 13%, and also includes Hf: 5.5%.

[0080] The performance test results of this comparative example sample are as follows: Mass magnetic susceptibility: 2.2 × 10⁻⁶ -6 cm3 / g; MRI compatibility: artifacts are present; Tensile strength: 580 MPa; Yield strength: 500 MPa; Elongation: 3%; Antibacterial rate: 90%; Self-corrosion current density: 6.2 × 10 -8 A / cm 2 .

[0081] The sources or properties of the raw materials used in the above embodiments and comparative examples of this application are as follows: Ti: φ3×3mm titanium particles, purity ≥99.95%, Shaanxi Zhonglianda Titanium Industry Co., Ltd.; Ag: φ3×3mm silver granules, purity ≥99.99%, Beijing Xingrongyuan Technology Co., Ltd.; Mo: 400 mesh molybdenum powder, purity ≥99.95%, Beijing Xingrongyuan Technology Co., Ltd.; Ta: 400 mesh tantalum powder, purity ≥99.95%, Beijing Xingrongyuan Technology Co., Ltd.; Hf: 400-mesh hafnium powder, purity ≥99.95%, Beijing Xingrongyuan Technology Co., Ltd.

[0082] The testing methods used in this application are as follows:

[0083] mass magnetic susceptibility The relative permeability of the titanium alloy in this application embodiment was measured according to the national standard GB / T 35690-2017 "Method for Measurement of Relative Permeability of Weakly Magnetic Materials" using the solenoid method, and the mass magnetic susceptibility was calculated according to the following formula:

[0084] in, For mass magnetic susceptibility, The relative permeability, This refers to the density of titanium alloy.

[0085] The density of the titanium alloy was measured in accordance with GB / T 3850-2015 "Method for Determination of Density of Dense Sintered Metallic Materials and Hard Alloys".

[0086] Magnetic Resonance Compatibility The magnetic resonance compatibility of the titanium alloy in the embodiments of this application was evaluated in accordance with the industry standard YY / T 0987.3-2016 "Magnetic Resonance Compatibility of Surgical Implants Part 3: Evaluation Method of Image Artifacts".

[0087] Mechanical properties The tensile mechanical properties of the titanium alloy in this application embodiment were measured in accordance with the national standard GB / T 228.1-2021 "Metallic materials - Tensile testing - Part 1: Test method at room temperature". These properties include yield strength, tensile strength and elongation.

[0088] Antibacterial rate The antibacterial properties of the titanium alloy in the embodiments of this application were determined in accordance with the national standard GB / T 31402-2023 "Determination of antibacterial activity of plastics and other non-porous materials".

[0089] Corrosion resistance The self-corrosion current density of the titanium alloy in this application embodiment was measured in accordance with the national standard GB / T 24196-2009 "Electrochemical Test Methods for Corrosion of Metals and Alloys - Guidelines for Measurement of Potentiostatic and Potentiodynamic Polarization". The experimental solution was 37℃ physiological saline, i.e., 0.9% mass concentration NaCl solution.

[0090] The test results of each embodiment and comparative example are shown in Table 1:

[0091] The results show that the low magnetic susceptibility high-strength titanium alloy of this application has a Ti2Ag particle phase dispersed in the matrix phase, such as... Figure 1 As shown.

[0092] As can be seen from the results of Examples 1-5 in Table 1, the low magnetic susceptibility high-strength titanium alloy of this application has a magnetic susceptibility of less than 1.2 × 10⁻⁶. -6 The NMR compatibility tests showed no artifacts, and the mass magnetic susceptibility was significantly lower than that of existing commercial titanium alloys, low-magnetic-susceptibility titanium alloys, and implant-grade titanium alloys. While maintaining a low mass magnetic susceptibility, this low-magnetic-susceptibility high-strength titanium alloy also exhibits high strength, good plasticity, high antibacterial rate, and high corrosion resistance. Furthermore, the type and content of the β-stabilizing element can be selected according to actual mechanical performance requirements.

[0093] The comparison between Examples 1 and 3 shows that when the Ag mass fraction is as low as 10%, only an appropriate amount of pure Mo is needed as a β-stabilizing element for the titanium alloy to achieve superior magnetic susceptibility, antibacterial rate, corrosion resistance, and strength, while also possessing a certain degree of plasticity for easy processing. When the Ag content reaches 13%, expensive Hf needs to be added to ensure that the titanium alloy meets the required performance.

[0094] The comparison results between Examples 2 and 4 show that when the Ag mass fraction is as high as 3%, only an appropriate amount of pure Ta is needed as a β-stabilizing element for the titanium alloy to achieve superior magnetic susceptibility, strength, antibacterial rate, and corrosion resistance, while also exhibiting good plasticity. When the Ag content is as low as 0.5%, expensive Hf needs to be added to achieve the required performance of the titanium alloy.

[0095] The comparison results between Example 1 and Comparative Example 2 show that, with the addition of an appropriate amount of Ag and an appropriate amount of β-stabilizing element, the magnetic susceptibility of the titanium alloy can be significantly reduced, and the strength, antibacterial rate and corrosion resistance of the titanium alloy are significantly improved, while good plasticity is also retained, which reflects the synergistic effect of the elements in this application.

[0096] The results of Example 3 and Comparative Example 3 show that when the silver content is high, the magnetic susceptibility of the titanium alloy is significantly reduced when the β-stabilizing element content reaches 5%, and the strength, antibacterial rate and corrosion resistance of the titanium alloy are significantly improved, while retaining excellent plasticity.

[0097] Based on the results of Example 3 and Comparative Example 5, it can be seen that when the content of β stabilizing element exceeds 30%, even with the addition of Hf element, it is difficult to obtain the low magnetic susceptibility high-strength titanium alloy of this application.

[0098] The results of Comparative Examples 4 and 5 show that, regardless of the silver content, it is difficult to obtain the low magnetic susceptibility high-strength titanium alloy of this application when the β stabilizing element content is less than 5%.

[0099] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of this application is limited to these examples; within the framework of this application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of this application as described above. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A high-strength titanium alloy with low magnetic susceptibility, characterized in that, The alloy comprises, by mass percentage, 0.5% to 13% Ag and 5.0% to 30% β-stabilizing elements, wherein the β-stabilizing elements include at least one of Mo and Ta, with the balance being Ti and unavoidable impurities; the phase composition of the low magnetic susceptibility high-strength titanium alloy comprises a β-Ti matrix phase and Ti2Ag particle phase, martensitic phase and ω phase dispersed in the matrix phase, wherein the β-stabilizing elements and part of Ag are dissolved in the β-Ti matrix.

2. The low magnetic susceptibility high-strength titanium alloy as described in claim 1, characterized in that, The β-stabilizing element also includes Hf.

3. The low magnetic susceptibility high-strength titanium alloy as described in claim 1, characterized in that, The volume fraction of the Ti2Ag particle phase is ≤8%, and the size of the Ti2Ag particles is ≤50 nm.

4. The low magnetic susceptibility high-strength titanium alloy as described in claim 1, characterized in that, The low-magnetic-susceptibility, high-strength titanium alloy has a mass magnetic susceptibility ≤1.2×10⁻⁶ at room temperature. -6 cm³ / g.

5. The low magnetic susceptibility high-strength titanium alloy as described in claim 1, characterized in that, The low magnetic susceptibility high-strength titanium alloy has a tensile strength ≥930MPa, a yield strength ≥860MPa, and an elongation ≥10% at room temperature.

6. The low magnetic susceptibility high-strength titanium alloy as described in claim 1, characterized in that, The mass percentage of Ag is 3% to 10%.

7. The low magnetic susceptibility high-strength titanium alloy as described in claim 1, characterized in that, The mass percentage of the β-stabilizing element is 10% to 25%.

8. A method for preparing a high-strength titanium alloy with low magnetic susceptibility, characterized in that, The low magnetic susceptibility high-strength titanium alloy is the low magnetic susceptibility high-strength titanium alloy as described in any one of claims 1-7, and the preparation method includes the following steps: Smelting: Prepare Ti, Ag and β stabilizing element raw materials according to element mass percentage, mix them evenly and press the electrode, and then perform vacuum arc melting on the electrode to obtain an ingot; The ingot is subjected to homogenization heat treatment, hot forging, hot rolling, solution treatment, cold deformation and aging treatment in sequence; The solution treatment involves heating the hot-rolled forging to 850°C to 950°C and holding it at that temperature for 1 to 3 hours. After holding, the forging is quenched in ice water at 0°C to 5°C to form a mixed structure of β phase and martensite.

9. The preparation method according to claim 8, characterized in that, The temperature of the cold deformation is ≤200℃.

10. The preparation method according to claim 8, characterized in that, The aging temperature is 300℃ to 550℃, and the holding time is 2h to 6h.

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