A low elastic modulus magnetic compatible Zr-Nb-Cu series biomedical alloy and a preparation method and application thereof

Abstract

The application discloses a kind of magnetic compatible Zr-Nb-Cu system biomedical alloy and its preparation method and application, the chemical composition of the biomedical alloy is calculated as follows by weight percentage: Nb:2.5~22%, Cu:0.8~1.2%, the balance is Zr and inevitable impurities;The alloy is obtained by proportioning, melting to uniformity, then solid solution treatment and furnace cooling to metal raw materials according to weight ratio.The magnetic compatible Zr-Nb-Cu system biomedical alloy of the application has lower magnetic susceptibility and elastic modulus than the currently commonly used biomedical alloy, and there is no biological toxicity element, can better serve the magnetic resonance imaging technology under higher magnetic field, reduce stress shielding effect and prevent the failure of implant.

Description

Technical Field

[0001] This invention belongs to the field of metallic materials technology, and relates to a zirconium alloy, specifically a low elastic modulus magnetically compatible Zr-Nb-Cu biomedical alloy, its preparation method, and its application. Background Technology

[0002] Magnetic resonance imaging (MRI) is a novel medical imaging technique. When a proton (¹H) of a hydrogen atom 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 ¹H. The technique of acquiring and using these radio signals for three-dimensional imaging 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. Under ultra-high magnetic fields, the magnetization rate of biomedical implants is particularly critical. Strong magnetic fields can have three adverse effects on metallic implants: ① displacement; ② heating affecting surrounding tissues; ③ artifacts during imaging. The area of ​​artifacts varies with 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 volume magnetic susceptibility. Furthermore, for Zr, its magnetic susceptibility (χ) is closely related to the phase composition; generally, χ... ω <χ α <χ β Studies have reported on β-Zr, which has a lower magnetic susceptibility. However, β-Zr has a slightly higher magnetic susceptibility than α-Zr and ω-Zr, resulting in greater artifacts on MRI.

[0003] Furthermore, after implantation, the implant interacts with the surrounding bone tissue through tension, compression, and bending forces due to bodily movement. The elastic modulus of the metal implant is higher than that of human bone (10–30 GPa), which prevents the effective transfer of force to adjacent bone tissue, creating a "stress shielding" effect. This leads to bone resorption around the implant, resulting in decreased bone thickness and osteoporosis, ultimately causing implant loosening or breakage and implantation failure. Therefore, it is crucial to minimize the elastic modulus of the metal implant and reduce the difference in elastic modulus between it and the bone tissue to minimize the damage to bone tissue caused by the "stress shielding" effect. For Zr, its elastic modulus is also closely related to its phase composition; generally, E... ω >E α >E β Therefore, although β-Zr has a slightly higher magnetic susceptibility than α-Zr and ω-Zr, it has a lower elastic modulus.

[0004] Therefore, in order to adapt to future strong magnetic field MRI and prevent the failure of metal implants, it is urgent to develop a magnetically compatible biomedical alloy material with low elastic modulus. Summary of the Invention

[0005] The purpose of this invention is to provide a low-elastic-modulus magnetically compatible Zr-Nb-Cu biomedical alloy to overcome the problems of artifacts and interference with the accuracy of diagnostic results caused by existing biomedical alloys with high magnetic susceptibility in strong magnetic field diagnosis; and to overcome the problems of loosening and failure of existing biomedical alloys with high elastic modulus after implantation.

[0006] To achieve its objective, the present invention employs the following technical solution:

[0007] A low-elastic-modulus magnetically compatible Zr-Nb-Cu biomedical alloy, wherein the chemical composition of the biomedical alloy, calculated by weight percentage, is: Nb: 2.5-22%, Cu: 0.8-1.2%, with the balance being Zr and unavoidable impurities.

[0008] Preferably, the chemical composition of the biomedical alloy, calculated by weight percentage, is: Nb: 2.5-14% or 14-22%, Cu: 0.8-1.2%, with the balance being Zr and unavoidable impurities;

[0009] Preferred Nb content: 2.5–5%, 5–14%, or 14–22%;

[0010] Preferably, Cu is 0.9% to 1.1%, and more preferably, Cu is 1%.

[0011] More preferably, the Zr-Nb-Cu biomedical alloy is Zr-2.5Nb-1Cu, Zr-5Nb-1Cu, Zr-14Nb-1Cu or Zr-22Nb-1Cu by weight percentage of chemical composition.

[0012] The biomedical alloy has a mass magnetic susceptibility of 1.35–1.80 × 10⁻⁶. -6 cm 3 g -1 The volume magnetic susceptibility is 75–113 × 10⁻⁶. -6 Its elastic modulus is 56–76 GPa.

[0013] The preparation method of the low elastic modulus magnetically compatible Zr-Nb-Cu biomedical alloy described in any 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℃, and the smelting equipment is filled with inert gas and smelted under a protective atmosphere;

[0016] (3) Perform a solution treatment and cool to obtain the product.

[0017] In step (1), the raw materials are sponge Zr, Nb blocks and Cu powder, and the purity of the raw materials is above 99.0 wt%.

[0018] In step (2), a refractory metal suspension melting device is used for melting, and the vacuum degree of the melting device is adjusted to 4×10. -3 MPa, to ensure uniform composition, the ingot was repeatedly turned over and remelted at least three times.

[0019] In step (3), the solution treatment temperature is 1000-1100℃, the holding time is 25-35 min, and the cooling method is furnace cooling.

[0020] The preferred solution treatment temperature is 1050℃, and the holding time is 30 min.

[0021] The present invention also provides the application of the alloy described in any of the above claims in the preparation of biomedical implants.

[0022] 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.

[0023] This invention employs the principle of alloying, obtaining a β phase with low elastic modulus by controlling the content of the β-Zr eutectic stabilizing element Nb; and alloying the Zr alloy by adding the β-Zr eutectoid stabilizing element Cu to form a Zr2Cu second phase with low magnetic susceptibility, thereby achieving the purpose of reducing magnetic susceptibility.

[0024] The technical solution of the present invention has the following beneficial effects:

[0025] ① The Zr-Nb-Cu biomedical alloy of this invention has a lower magnetic susceptibility, which can reduce artifacts during MRI diagnosis; ② The Zr-Nb-Cu biomedical alloy of this invention has a lower elastic modulus (56-76 GPa) to match human bone structure and avoid stress shielding effect leading to implant failure; ③ The alloying elements selected for the Zr-Nb-Cu biomedical alloy of this invention are all non-cytotoxic elements, avoiding harm to the human body; ④ Experiments have shown that the furnace-cooled Zr-2.5Nb-1Cu alloy has the potential to become a magnetically compatible orthopedic implant, with both low magnetic susceptibility and elastic modulus; ⑤ The alloy prepared by this invention can be used in MRI with higher magnetic fields, making up for the shortcomings of traditional biomedical alloys. Attached Figure Description

[0026] Figure 1 These are microscopic images of the tissue from Embodiment 1 of the present invention.

[0027] Figure 2 These are microscopic images of the tissue from Embodiment 2 of the present invention.

[0028] Figure 3 These are microscopic images of the tissue from Embodiment 3 of the present invention.

[0029] Figure 4 These are microscopic images of the tissue from Embodiment 4 of the present invention.

[0030] Figure 5 The results show the mass magnetic susceptibility and elastic modulus of the embodiments and comparative examples of the present invention.

[0031] Figure 6 These are the volume magnetic susceptibility and elastic modulus results of the embodiments and comparative examples of the present invention. Detailed Implementation

[0032] 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.

[0033] 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.

[0034] The magnetically compatible Zr-Nb-Cu biomedical alloy of the present invention has the following chemical composition by weight percentage: niobium (Nb): 2.5-22%, copper (Cu): 0.8-1.2%, with the balance being zirconium (Zr) and unavoidable impurities.

[0035] The magnetically compatible Zr-Nb-Cu biomedical alloy of the present invention is prepared using conventional methods in the art. For example, it can be prepared by following these steps:

[0036] (1) Raw material weighing: Select industrial-grade Zr, Nb blocks and Cu powder with a purity of over 99.0 wt% as raw materials according to the type of alloy element composition, and weigh and batch them according to the weight percentage.

[0037] (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 ingot was melted at MPa under argon protection, and to ensure uniform composition, it was repeatedly turned over and remelted at least three times.

[0038] (3) Solution treatment: The ingot is cut into blocks by wire cutting and polished with sandpaper. The polished blocks are placed in a quartz tube, vacuum sealed, and heated in a heat treatment furnace to 1050°C for 30 minutes. Then, they are slowly cooled in the furnace to obtain the final product.

[0039] Following the method described above, the alloy products of Examples 1-4 in Table 1 were prepared, and the mass magnetic susceptibility and elastic modulus of the products were tested. In Table 1, the numbers preceding the metallic elements in the alloy proportions represent the weight percentage of that element, with the balance being Zr and unavoidable impurities. For example, Zr-2.5Nb-1Cu represents the alloy's chemical composition by weight percentage: Nb: 2.5%, Cu: 1%, with the balance being Zr and unavoidable impurities; the alloy proportions in other examples follow the same principle.

[0040] The magnetic susceptibility measurement method of the alloy was based on 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). The specific steps are 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. Then, it was placed in a vibrating magnetometer (VSM) with a magnetic field strength of 1T and the magnetic field direction perpendicular to the 4*4mm plane. The obtained data were linearly fitted using Origin software. The slope of the straight line is 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).

[0041] The method for measuring the elastic modulus of the alloy 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 performed 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.

[0042] The proportions of the prepared alloy products are shown in Table 1, and the results of magnetic susceptibility and elastic modulus are shown in Table 1 and Table 2. Figure 5-6 In all embodiments, the mass magnetic susceptibility and elastic modulus were lower than those of the comparative example. With the increase of the β-stabilizing element Nb content, the mass magnetic susceptibility of the alloy increased slightly, while the elastic modulus showed a trend of first increasing and then decreasing.

[0043] Table 1 shows the mass magnetic susceptibility and elastic modulus of the comparative examples and embodiments.

[0044]

[0045] The material Ti-6Al-4V in Comparative Example 2 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 1-4 are significantly lower than those of Ti-6Al-4V. Among the alloy products in Examples 1-4, the Zr-2.5Nb-1Cu alloy has the lowest magnetic susceptibility and lower elastic modulus, thus possessing greater potential as a magnetically compatible orthopedic implant compared to the other three examples.

[0046] The microstructure of the alloy sample from Example 1 was observed using scanning electron microscopy. The microstructure of the sample from Example 1 is as follows: Figure 1 As shown, the alloy consists of α-Zr, β-Zr, and Zr₂Cu. Figure 1 The white striped areas correspond to the β phase, the gray striped areas correspond to the α phase, and the black dotted areas correspond to Zr₂Cu. The black dotted areas are formed because the Zr₂Cu phase is not resistant to corrosion during electrolytic polishing and is preferentially corroded away, forming pits.

[0047] The microstructure of the alloy sample from Example 2 was observed using scanning electron microscopy. The microstructure of the sample from Example 2 is as follows: Figure 2 As shown, the tissue structure of Example 2 is similar to that of Example 1, but the β-Zr lamellars are finer and the content is lower.

[0048] The alloy sample of Example 3 was observed under scanning electron microscopy and transmission electron microscopy. The microstructure of the sample of Example 3 is as follows: Figure 3 As shown, the alloy consists of α-Zr, β-Zr and ω phases. Figure 3 The equiaxial grains are β phase, the dark gray areas are α phase; the ω phase is dispersed inside the β grains.

[0049] The microstructure of the alloy sample from Example 4 was observed using scanning electron microscopy. The microstructure of the sample from Example 4 is as follows: Figure 4 As shown, the alloy consists of a single β-Zr.

[0050] Example 1 and Example 2 are both composed of three phases: β phase, α phase and Zr2Cu. The β phase has the characteristic of low elastic modulus, while Zr2Cu and α phase have the characteristic of low magnetic susceptibility. Example 3 is composed of β+ω+α phase. The ω phase and α phase have the characteristic of low magnetic susceptibility, while the β phase has the characteristic of low elastic modulus. Example 4 is composed of β phase, and the alloy has the characteristic of low elastic modulus.

Claims

1. A low-elastic-modulus, magnetically compatible Zr-Nb-Cu biomedical alloy, characterized in that: The chemical composition of the biomedical alloy, calculated by weight percentage, is: Nb: 2.5~22%, Cu: 0.8~1.2%, with the balance being Zr and unavoidable impurities; the mass magnetic susceptibility of the biomedical alloy is 1.35~1.80×10⁻⁶. -6 cm 3 g -1 The volume magnetic susceptibility is 75~113×10 -6 Its elastic modulus is 56~76 GPa.

2. The low elastic modulus magnetically compatible Zr-Nb-Cu biomedical alloy according to claim 1, characterized in that: The biomedical alloy contains 0.9-1.1% Cu.

3. The low elastic modulus magnetically compatible Zr-Nb-Cu biomedical alloy according to claim 2, characterized in that: The Zr-Nb-Cu biomedical alloys are Zr-2.5Nb-1Cu, Zr-5Nb-1Cu, Zr-14Nb-1Cu, or Zr-22Nb-1Cu according to the weight percentage of their chemical composition.

4. The method for preparing the low elastic modulus magnetically compatible Zr-Nb-Cu biomedical alloy according to any one of claims 1 to 3, 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℃, and the smelting equipment is filled with inert gas and smelted under a protective atmosphere; (3) Perform a solution treatment and cool to obtain the product.

5. The preparation method according to claim 4, characterized in that: In step (1), the raw materials are sponge Zr, Nb blocks and Cu powder, and the purity of the raw materials is above 99.0 wt%.

6. The preparation method according to claim 4, characterized in that: In step (2), a refractory metal suspension smelting device is used for smelting, and the vacuum degree of the smelting device is adjusted to 4×10. -3 MPa, to ensure uniform composition, the ingot was repeatedly turned over and remelted at least three times.

7. The preparation method according to claim 4, characterized in that: In step (3), the solution treatment temperature is 1000~1100℃ and the holding time is 25~35min; the cooling method is furnace cooling.

8. The use of the alloy according to any one of claims 1 to 3 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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