A magnetically compatible beta biomedical zirconium alloy and a preparation method and application thereof

Abstract

The application discloses a kind of magnetic compatible β-Zr type biomedical alloys and its preparation method and application, the chemical composition of the biomedical alloy is calculated as follows by weight percentage: niobium 21.0~23.0%, copper 2.8~15.2%, the balance is zirconium and inevitable impurities.The β-Zr type biomedical alloy of the application has lower magnetic susceptibility than the currently commonly used biomedical alloy, and lower elastic modulus, and there is no biological toxic element, can better serve the magnetic resonance imaging technology under higher magnetic field.

Description

Technical Field

[0001] This invention belongs to the field of metallic materials, and relates to zirconium-based biomedical alloys, specifically to a magnetically compatible β-type biomedical zirconium alloy, its preparation method, and its application. Background Technology

[0002] Magnetic resonance imaging (MRI) is a novel medical imaging technique. When a hydrogen atom's proton (¹H) in a substance resonates with a radio frequency at a certain frequency under the influence of an external magnetic field, and the radio frequency is removed, the proton generates a weak radio signal as it returns to its initial state. Different tissues produce different radio signals from their ¹H atoms. The technique of acquiring and using these radio signals to create three-dimensional images is called magnetic resonance imaging. The higher the magnetic field strength, the higher the resolution of the MRI. In recent years, the research on "Electrical Engineering Theory and Key Technologies of Advanced Magnetic Resonance Imaging Systems" has been one of the major projects of the School of Engineering and Materials Science. This research aims to solve problems such as the degradation of magnet performance in MRI systems under ultra-high magnetic fields and ensure the independent controllability of advanced MRI technology.

[0003] Under ultra-high magnetic fields, the magnetic susceptibility of biomedical implants becomes particularly critical. Strong magnetic fields can cause three adverse effects on metallic implants: ① displacement and misalignment; ② heating that affects surrounding tissues; ③ artifacts during imaging. The artifact area varies depending on the implant and human tissue (-10 to -7 × 10⁻⁶). -6 The area of ​​the artifact is related to the difference in magnetic susceptibility between Zr (10⁹ × 10⁻⁶). The larger the difference in magnetic susceptibility, the larger the artifact area. -6 It has more advantages than currently used pure Ti (170×10) -6 Ti-6Al-4V (179×10) -6 ), stainless steel (3520~6700×10) -6 ) and Co-Cr (960×10 -6 The alloy has a lower volumetric magnetic susceptibility. Furthermore, for Zr, its phase composition is closely related to the magnetic susceptibility (χ), which is generally higher. ω <χ α <χ β .

[0004] Beta-type titanium-based materials are widely used in biomedical metal-based implants due to their low elastic modulus. However, with the widespread use of strong magnetic field MRI, beta-type titanium-based materials, due to their high magnetic susceptibility, will produce artifacts during imaging under strong magnetic fields. Therefore, developing a novel metal-based biomedical material with low magnetic susceptibility and a low elastic modulus has become a research hotspot in this field.

[0005] β-Zr possesses a lower mass magnetic susceptibility than β-Ti, while exhibiting mechanical properties, corrosion resistance, and biocompatibility comparable to titanium alloys. Currently reported β-Zr with lower magnetic susceptibility has a higher susceptibility than α-Zr and ω-Zr, resulting in greater artifacts on MRI. Research on zirconium alloys in MRI has primarily focused on α-type or α+ω-type alloys with lower magnetic susceptibility, while β-Zr, due to its higher magnetic susceptibility, has received relatively few reports. Summary of the Invention

[0006] The purpose of this invention is to provide a magnetically compatible β-Zr type biomedical alloy to overcome the problem of artifacts generated by existing biomedical alloys with high magnetic susceptibility in strong magnetic field diagnostics. It possesses good biocompatibility, good mechanical properties and corrosion resistance, while also exhibiting low magnetic susceptibility and elastic modulus.

[0007] To achieve its objective, the present invention employs the following technical solution:

[0008] A magnetically compatible β-Zr type biomedical alloy, wherein the chemical composition of the biomedical alloy, by weight percentage, is: 21.0-23.0% niobium, 2.8-15.2% copper, with the balance being zirconium and unavoidable impurities.

[0009] Preferably, the chemical composition of the biomedical alloy, calculated by weight percentage, is: 21.5-22.5% niobium, 3.0-15.2% copper, with the balance being zirconium and unavoidable impurities.

[0010] Preferably, the chemical composition of the biomedical alloy, calculated by weight percentage, is: 21.5-22.5% niobium, 6.0-15.2% copper, with the balance being zirconium and unavoidable impurities; more preferably, 22% niobium and 6.0-15.0% copper.

[0011] Preferably, the chemical composition of the biomedical alloy, calculated by weight percentage, is: 21.5-22.5% niobium, 10.0-15.2% copper, with the balance being zirconium and unavoidable impurities; more preferably 21.5-22.5% niobium and 13.0-15.0% copper; even more preferably 22.0% niobium and 15.0% copper.

[0012] The biomedical alloy has a mass magnetic susceptibility of 0.95–1.70 × 10⁻⁶. -6 cm 3 g -1 The volume magnetic susceptibility is 77–138 × 10⁻⁶. -6 Its elastic modulus is 68.8–82.9 GPa.

[0013] The preparation method of the magnetically compatible β-Zr type biomedical alloy described in any one of the above claims includes the following steps:

[0014] (1) Weighing raw materials: Take raw materials Zr, Nb and Cu, and weigh them according to their weight percentages;

[0015] (2) Alloy smelting: The smelting temperature is 2700~3000℃. Inert gas is introduced into the smelting equipment to smelt the ingot under a protective atmosphere, and then it is quenched to obtain the alloy.

[0016] The raw materials are sponge zirconium, niobium blocks and copper blocks, and the purity of the raw materials is above 99.0 wt%.

[0017] Preferably, a refractory metal suspension smelting device is used for smelting, and the vacuum degree of the smelting device is adjusted to 4×10⁻⁶. - 3 To ensure uniform composition, the ingot was repeatedly turned and remelted at least three times; refractory metal suspension melting equipment was used for melting, with a melting temperature of 2700–3000℃, and the vacuum degree of the melting equipment was adjusted to 4 × 10 MPa. -3 The alloy is heated to MPa and smelted under argon protection. To ensure uniform composition, the ingot is repeatedly turned over and remelted at least three times. The alloy is then quenched at 950–990°C and water-cooled to room temperature to obtain the final product.

[0018] The present invention also provides the application of the alloy described in any of the above claims in the preparation of biomedical implants.

[0019] Preferably, the biomedical implant is a human implant, such as a bone fixation clip, skull, hip joint, shoulder joint, knee joint, vasodilator, or heart valve.

[0020] This invention employs the addition of varying amounts of the β-Zr segregating element Cu to β-type Zr-Nb alloys to alloy the Zr alloy, forming Zr₂Cu second-phase particles with low magnetic susceptibility, thereby reducing the magnetic susceptibility of the Zr alloy. The magnitude of the alloy's magnetic susceptibility is determined using the empirical formula χ. m =χ β V β +χ Zr2Cu V Zr2Cu An evaluation was conducted, and it was found that increasing the Cu content in the alloy would increase the volume of Zr₂Cu, thereby reducing the alloy's magnetic susceptibility.

[0021] The technical solution of the present invention has the following beneficial effects:

[0022] ① The invented magnetically compatible β-Zr type biomedical alloy has a lower magnetic susceptibility (mass magnetic susceptibility of 0.95~1.70×10⁻⁶). -6 cm 3 g -1 The volume magnetic susceptibility is 77–138 × 10⁻⁶. -6While ensuring a low elastic modulus (68.8–82.9 GPa), it is suitable for matching human tissue during MRI diagnosis; ② The alloying elements selected for the magnetically compatible β-Zr biomedical alloy of this invention are all non-cytotoxic elements, avoiding harm to the human body. ③ Experiments have shown that when the copper content is 15 wt%, the alloy has the lowest magnetic susceptibility, showing potential as a magnetically compatible medical orthopedic implant. ④ The alloy prepared by this invention can be used in MRI with higher magnetic fields, making up for the shortcomings of traditional biomedical alloys in the biomedical field. Attached Figure Description

[0023] Figure 1 This is a SEM image of the alloy from Embodiment 1 of the present invention.

[0024] Figure 2 This is a SEM image of the alloy from Embodiment 2 of the present invention.

[0025] Figure 3 This is a SEM image of the alloy in Example 3 of the present invention.

[0026] Figure 4 This is a SEM image of the alloy of Comparative Example 1 of this invention.

[0027] Figure 5 The results show the mass magnetic susceptibility and elastic modulus of the alloys in Examples 1-3 and Comparative Examples 1-3 of this invention.

[0028] Figure 6 These are the volume magnetic susceptibility and elastic modulus results of the alloys in Examples 1-3 and Comparative Examples 1-3 of this invention. Detailed Implementation

[0029] To fully understand the purpose, features, and effects of this invention, the following detailed embodiments are provided. Unless otherwise specified, the processes or apparatus involved in this invention are conventional methods or apparatus in the art. Unless otherwise stated, the following terms and concepts have the meanings commonly understood by those skilled in the art.

[0030] The present invention will be further illustrated by way of embodiments below, but the present invention is not limited to the scope of the embodiments described herein.

[0031] The magnetically compatible β-Zr biomedical alloy of the present invention has the following chemical composition by weight percentage: 21-23% niobium (Nb), 2.8-15.2% copper (Cu), and the balance being zirconium (Zr) and unavoidable impurities.

[0032] The magnetically compatible β-Zr biomedical alloy of the present invention is prepared using conventional methods in the art. For example, it can be prepared by following these steps:

[0033] (1) Raw material weighing: Select industrial-grade sponge zirconium, niobium blocks and copper blocks with a purity of more than 99.0 wt% as raw materials according to the type of alloy element composition, and weigh and batch them according to the weight percentage.

[0034] (2) Alloy smelting: Smelting is carried out using a refractory metal suspension smelting equipment at a smelting temperature of 2700–3000℃, with the vacuum degree of the smelting equipment adjusted to 4×10⁻⁶. -3 The alloy is heated to MPa and smelted under argon protection. To ensure uniform composition, the ingot is repeatedly turned over and remelted at least three times. The alloy is then quenched at 950-990℃, held for 30 minutes, and then water-cooled to room temperature to obtain the final product.

[0035] Zr alloys of Examples 1-3 and Comparative Example 1 were prepared according to the above method, and their chemical compositions by weight percentage are shown in Table 1.

[0036] Testing the magnetic susceptibility and elastic modulus of alloy products:

[0037] 1. The magnetic susceptibility measurement method refers to GB / Z 26082-2010 "Method for Measurement of DC Magnetic Susceptibility (Magnetic Moment) of Nanomaterials" and the literature (Suyalatu, N. Nomura, K. Oya, et al. Acta Biomaterialia 6(2010)1033-1038. Doi:10.1016 / j.actbio.2009.09.013), specifically as follows: A 4*4*2mm cube sample was cut from the ingot by wire cutting. The oxide scale on the surface was cleaned with metallographic sandpaper, and then placed in a vibrating magnetometer (VSM) with a magnetic field strength of 3T and the magnetic field direction perpendicular to the 4*4mm plane. The obtained data were linearly fitted using Origin software, and the slope of the straight line was the mass magnetic susceptibility (χ). m Then convert it to volume magnetic susceptibility (χ). v The formula is χ. v =χ m ×ρ×4π, (ρ is the density of the alloy, and π is pi).

[0038] 2. The measurement method of elastic modulus refers to GB / T 8653-2007 "Test Methods for Elastic Modulus, Chordic Modulus and Tangent Modulus of Metallic Materials". The specific measurement method is as follows: A block of a specific size is cut from the ingot by wire cutting, and the corresponding heat treatment process is carried out. Then, the block is further processed by wire cutting to obtain a tensile specimen. A tensile test is carried out using a universal tensile testing machine equipped with an optical extensometer to obtain the stress-strain curve. The stress-strain curve is then linearly fitted to obtain the corresponding elastic modulus.

[0039] The test results are shown in Table 1.

[0040] Table 1. Alloy composition, magnetic susceptibility, and elastic modulus of Zr-22Nb-xCu

[0041]

[0042] The SEM image and selected area electron diffraction pattern of the alloy sample obtained in Example 1 are shown below. Figure 1 As shown, the grayish-white matrix is ​​β-Zr, and the black granular or strip-like phases within the matrix and at grain boundaries are Zr₂Cu phases. The Zr₂Cu phases are distributed in different morphologies at grain boundaries and within grains. The mass magnetic susceptibility and elastic modulus are as follows: Figure 5 As shown, the mass magnetic susceptibility of the Zr-22Nb-3Cu alloy is 1.70 × 10⁻⁶. - 6 cm 3 g -1 Its elastic modulus is 68.8 GPa.

[0043] SEM images of the alloy samples obtained in Example 2 are shown below. Figure 2 As shown, the selected area electron diffraction structure is the same as in Example 1, and the mass magnetic susceptibility and elastic modulus are as follows. Figure 5 As shown, with the increase of Cu element, the volume of the Zr₂Cu phase gradually increases, and the magnetic susceptibility gradually decreases. The mass magnetic susceptibility of the Zr-22Nb-6Cu alloy is 1.39 × 10⁻⁶. -6 cm 3 g -1 Its elastic modulus is 71.7 GPa.

[0044] SEM images of the alloy samples obtained in Example 3 are shown below. Figure 3 As shown, the selected area electron diffraction structure is the same as in Example 1, and the mass magnetic susceptibility and elastic modulus are as follows. Figure 5 As shown, with the increase of Cu content, the volume of the Zr₂Cu phase gradually increases, and the magnetic susceptibility gradually decreases. The mass magnetic susceptibility of the Zr-22Nb-15Cu alloy is 0.95 × 10⁻⁶. -6 cm 3 g -1 Its elastic modulus is 82.9 GPa.

[0045] SEM images of the alloy samples obtained in Comparative Example 1 are shown below. Figure 4 As shown, due to the small amount of Cu added, no Zr₂Cu phase exists at the grain boundaries or within the grains. The mass magnetic susceptibility and elastic modulus are as follows: Figure 5 As shown, the mass magnetic susceptibility of the Zr-22Nb-1Cu alloy is 1.80 × 10⁻⁶. -6 cm 3 g -1 The elastic modulus is 62.5 GPa. The magnetic susceptibility and elastic modulus of Comparative Examples 2 and 3 are as follows: Figure 5 and Figure 6As shown in Table 1, the material Ti-6Al-4V in Comparative Example 3 is currently the most widely used bio-alloy. As can be seen from Table 1, the magnetic susceptibility and elastic modulus of the alloy products in Examples 1-3 are significantly lower than those of Ti-6Al-4V.

[0046] As shown in Table 1, the magnetic susceptibility gradually decreases while the elastic modulus gradually increases with increasing copper content. This is because the Zr₂Cu phase formed by copper and the zirconium matrix has low magnetic susceptibility but high elastic modulus. The higher the copper content, the larger the volume percentage of the Zr₂Cu phase in the alloy, resulting in lower magnetic susceptibility. When the copper content reaches 15 wt%, this designed alloy exhibits the lowest magnetic susceptibility compared to Comparative Example 1 and the other two designed alloys, approximately half that of the alloy with 1 wt% copper content, while maintaining a low elastic modulus. Therefore, it has greater potential for application in MRI.

Claims

1. A magnetically compatible β-Zr type biomedical alloy, characterized in that: The chemical composition of the biomedical alloy, calculated by weight percentage, is: 21.0~23.0% niobium, 2.8~15.2% copper, with the balance being zirconium and unavoidable impurities; the mass magnetic susceptibility of the biomedical alloy is 0.95~1.70×10⁻⁶. -6 cm 3 g -1 The volume magnetic susceptibility is 77~138×10 -6 Its elastic modulus is 68.8~82.9 GPa; The preparation method of the biomedical alloy includes the following steps: (1) Weighing raw materials: Take raw materials Zr, Nb and Cu, and weigh them according to their weight percentages; (2) Alloy smelting: The smelting temperature is 2700-3000℃. Inert gas is introduced into the smelting equipment to smelt the ingot under a protective atmosphere. Then, it is quenched at 950-990℃ and cooled to room temperature to obtain the alloy.

2. The magnetically compatible β-Zr type biomedical alloy according to claim 1, characterized in that: The chemical composition of the biomedical alloy, calculated by weight percentage, is: 21.5-22.5% niobium, 3.0-15.2% copper, with the balance being zirconium and unavoidable impurities.

3. The magnetically compatible β-Zr type biomedical alloy according to claim 2, characterized in that: The chemical composition of the biomedical alloy, calculated by weight percentage, is: 21.5-22.5% niobium, 6.0-15.2% copper, with the balance being zirconium and unavoidable impurities.

4. The magnetically compatible β-Zr type biomedical alloy according to claim 3, characterized in that: The chemical composition of the biomedical alloy, calculated by weight percentage, is: 21.5-22.5% niobium, 10.0-15.2% copper, with the balance being zirconium and unavoidable impurities.

5. The method for preparing the magnetically compatible β-Zr type biomedical alloy according to any one of claims 1 to 4, characterized in that, Includes the following steps: (1) Weighing raw materials: Take raw materials Zr, Nb and Cu, and weigh them according to their weight percentages; (2) Alloy smelting: The smelting temperature is 2700-3000℃. Inert gas is introduced into the smelting equipment to smelt the ingot under a protective atmosphere. Then, it is quenched at 950-990℃ and cooled to room temperature to obtain the alloy.

6. The preparation method according to claim 5, characterized in that: The raw materials are sponge zirconium, niobium blocks and copper blocks, and the purity of the raw materials is above 99.0 wt%.

7. The preparation method according to claim 5, characterized in that: The smelting was carried out using a refractory metal suspension smelting equipment, and the vacuum degree of the smelting equipment was adjusted to 4×10. -3 To ensure uniform composition, the ingot was repeatedly turned and remelted at least three times; refractory metal suspension melting equipment was used for melting, with a melting temperature of 2700~3000℃, and the vacuum degree of the melting equipment was adjusted to 4×10 MPa. -3 The alloy is heated to MPa and smelted under argon protection. To ensure uniform composition, the ingot is repeatedly turned over and remelted at least three times. The alloy is then quenched at 950~990℃ and water-cooled to room temperature to obtain the final product.

8. The use of the alloy according to any one of claims 1 to 4 in the preparation of biomedical implants.

9. The application according to claim 8, characterized in that: The biomedical implants mentioned are human implants.

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