An anti-aging biodegradable zinc alloy for medical use and its preparation method

Abstract

This invention relates to the field of biodegradable metallic material preparation technology, specifically to a biodegradable zinc alloy biomedical material and its preparation method. The alloy, by weight percentage, comprises the following elements: Cu 0.1–1%, Al 0.1–0.5%, Ti 0–0.5%, Y 0.01–0.1%, with the balance being Zn; the zinc alloy forms a bimodal grain structure and exhibits multi-level TiZn crystals. 15 Phase particle and size multi-level YZn 11 Phase particles. The preparation method is as follows: raw materials are taken according to the designed group allocation, and then melted and cast to obtain a cast product. The cast product is then subjected to homogenization treatment with appropriate parameters, hot extrusion deformation, alternating multiple cold drawing and low-temperature annealing treatments, and aging treatment to obtain the final product. This invention features a reasonable component design, a simple and controllable preparation process, and a product with excellent mechanical properties and outstanding anti-aging properties, facilitating industrial application.

Description

Technical Field

[0001] This invention relates to the field of biodegradable metal material preparation technology, specifically to a biodegradable zinc alloy biomedical material and its preparation method. Background Technology

[0002] Compared to traditional biodegradable iron-based and magnesium-based alloys, zinc-based biodegradable metallic materials offer good biocompatibility and a more suitable degradation rate, making them promising for applications in biomedical cardiovascular stent implants and bone repair. An ideal cardiovascular stent should possess excellent overall performance, requiring a tensile strength ≥350 MPa and an elongation ≥25%.

[0003] However, the mechanical properties of as-cast pure zinc and its hot-deformed form are poor, with tensile strength less than 180 MPa and elongation less than 2%, making it difficult to meet the requirements for use in medical cardiovascular stents. Due to the low melting point of zinc and zinc alloys, their recrystallization temperature is only around 15°C. During hot deformation processing above this temperature, dynamic recrystallization occurs, refining the grains and increasing the yield strength to near the tensile strength. Simultaneously, the dynamic recrystallization process is accompanied by a decrease in dislocation density. As plastic deformation progresses, zinc and zinc alloys become difficult to further strengthen and harden, resulting in reduced uniform elongation, uneven deformation, and fracture in localized areas due to excessive deformation. Another problem facing zinc and zinc alloys is insufficient anti-aging ability; their plasticity gradually decreases after being left at room temperature for a period of time. Currently, mechanical properties are mainly improved through alloying and subsequent plastic deformation. Common systems such as ZnMg, ZnLi, ZnMn, and ZnCu systems have good effects on improving strength or elongation, but few studies have focused on their work hardening ability and anti-aging ability. This invention addresses the problems of insufficient work hardening capacity and easy aging of zinc alloys by disclosing a high-strength, high-toughness, anti-aging, and biodegradable zinc alloy with sustainable work hardening, as well as its preparation method and applications. Summary of the Invention

[0004] This invention addresses the problems existing in biodegradable medical zinc alloys by providing an anti-aging biodegradable medical Zn-Cu-Al-Ti-Y alloy with enhanced work hardening ability and excellent toughness.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] The present invention discloses an anti-aging medical biodegradable zinc alloy, wherein the alloy is composed of the following elements by weight percentage: Cu 0.1-1%, Al 0.1-0.5%, Ti 0-0.5%, Y 0.01-0.1%, and the balance being Zn.

[0007] As a preferred embodiment, the present invention provides an anti-aging medical biodegradable zinc alloy, wherein the alloy is composed of the following elements by weight percentage: Cu 0.3-1%, Al 0.2-0.5%, Ti 0-0.5%, Y 0.01-0.1%, with the balance being Zn.

[0008] As a further preferred option, the sum of the mass percentages of Cu, Al, Ti, and Y is less than or equal to 2%.

[0009] As a further preferred embodiment, the present invention provides an anti-aging medical biodegradable zinc alloy, wherein the alloy is composed of the following elements by weight percentage: Cu 0.5-1%, Al 0.3-0.5%, Ti 0.2-0.5%, Y 0.05-0.1%, with the balance being Zn.

[0010] Of course, in this invention, the alloy, by weight percentage, Cu: 0.5%, Al: 0.3%, Ti: 0.25%, Y: 0.05%, with the balance being Zn; or Cu: 1%, Al: 0.45%, Ti: 0.45%, Y: 0.09%, with the balance being Zn, also exhibits excellent mechanical properties and anti-aging properties.

[0011] This zinc alloy exhibits a "bimodal grain structure + multi-level TiZn" 15 (Nanoscale + Submicronscale + Micronscale) + Multi-level Size YZn 11 "Phase particles (nanoscale + submicron scale + micron scale)" are specific structures.

[0012] This invention relates to an anti-aging medical biodegradable zinc alloy, wherein the recrystallized grain ratio is within 55-65%.

[0013] The roles of alloying elements in this invention are described below:

[0014] Cu, an essential trace element for the human body, can promote the proliferation of vascular endothelial cells and accelerate the process of vascular revascularization. A deficiency of Cu in the human body can lead to hemophagocytic anemia, neuropathy, and disorders of glucose and cholesterol metabolism. Cu deficiency also has adverse effects on the cardiovascular system, such as atrial thrombosis and coronary artery necrosis.

[0015] At 425℃, the solid solution content of Cu in Zn is approximately 2.75%. The addition of an appropriate amount of Cu can effectively improve the strength and plasticity of zinc alloys, providing solid solution strengthening and second-phase strengthening effects. Simultaneously, since Cu has a melting point as high as 1085℃, far exceeding that of Zn (419.5℃), the addition of an appropriate amount of Cu in materials with low-melting-point Zn as the matrix can hinder dynamic recrystallization and significantly improve the thermal stability of the Zn matrix, thereby greatly enhancing the anti-aging properties of Zn alloys.

[0016] Adding Al to Zn-Cu alloys can improve their casting properties, increase their fluidity, refine their grains, induce solid solution strengthening, and enhance their mechanical properties. Although excessively high concentrations of aluminum ions in the human body can lead to toxic side effects, concentrations below 10 μmol / L can actually promote cell proliferation and metabolism. Furthermore, since people inevitably ingest aluminum daily from food, adding appropriate amounts of aluminum can modify zinc alloys.

[0017] Ti exhibits good biocompatibility. Due to its very low solid solubility in the Zn matrix, Ti is primarily distributed as a dispersed intermetallic compound, TiZn. 15 The presence of these second phases also leads to a significant refinement of the Zn matrix grains.

[0018] Y has a melting point of 1522℃. (German Center for Magnesium Alloy Innovation) S et al. investigated the deformation mechanism of Y in Mg alloys. Their results showed that adding an appropriate amount of Y reduced the non-basal plane slip stacking fault energy, thereby promoting the initiation of non-basal plane slip and improving the alloy's plasticity. Due to the extremely low solid solubility of Y in the zinc matrix, the resulting YZn... 11 When the size and distribution of the second-phase particles are reasonable, the strength and toughness of the alloy material can be significantly improved.

[0019] Secondly, the present invention also provides a method for preparing the aforementioned medical biodegradable Zn-Cu-Al-Ti-Y pentagonal alloy, comprising the following steps:

[0020] S1: Prepare the raw materials according to the alloy composition design.

[0021] S2: The prepared raw materials are smelted and cast to obtain a cast zinc alloy.

[0022] S3: After homogenization treatment, the cast zinc alloy is subjected to hot extrusion deformation. The extruded zinc alloy is then subjected to multiple cold drawing and low-temperature annealing alternating processes. Finally, medical biodegradable Zn-Cu-Al-Ti-Y alloys with different property combinations are obtained through aging treatment. The hot extrusion deformation temperature is 200-300℃, the extrusion ratio is 15-23:1, and the drawing speed is 20-30mm / s. The low-temperature annealing temperature is 160-300℃, and the number of drawing cycles is greater than or equal to 8, with the highest annealing temperature after the first drawing, decreasing thereafter. The aging temperature is 25-200℃.

[0023] S4: The biodegradable zinc alloy wire is laser-cut into shape, polished with sandpaper and electrochemically, and then surface modified. The surface modification method can be one or more of surface carburizing, sandblasting, and passivation.

[0024] Because aluminum has a low melting point, it is added in the form of pure metal. Titanium and yttrium have higher melting points, so they are added in the form of master alloys. Specifically, zinc-copper master alloy, copper-titanium master alloy, and zinc-yttrium master alloy are smelted separately. In practice, the zinc-copper master alloy, copper-titanium master alloy, zinc-yttrium master alloy, pure zinc ingot, and pure aluminum ingot are smelted together. Argon gas is introduced into the alloy melt during the smelting process. After refining, settling, and casting, a cast zinc alloy is obtained.

[0025] Preferably, the temperature of the smelting process in steps S1 and S2 is 560–1120°C.

[0026] Preferably, the homogenization process in step S3 is as follows: vacuum insulation or isostatic pressing with inert gas at 1-50 MPa for 5-15 hours at a temperature of 120-400℃, followed by rapid water cooling to obtain a supersaturated solid solution.

[0027] As a preferred method, homogenization treatment is performed: first, the surface layer of the above-mentioned ingot blank is removed by machining; then, the cast zinc alloy ingot is held at 280–300°C in an argon protective atmosphere for 2–4 hours, followed by heating to 320–340°C and holding for 4–8 hours, and finally cooled to room temperature in water. This operation can improve the segregation of elements in the zinc alloy.

[0028] Preferably, the hot extrusion deformation process in step S3 is carried out at a temperature of 240-260°C and an extrusion ratio of 21-23:1. Before extrusion, a layer of graphite is uniformly coated on the surface of the mold as a lubricant.

[0029] Preferably, the specific drawing process in step S3 is as follows: drawing at room temperature, a drawing speed of 20-40 mm / s, and a total of 13-18 drawing passes. After each drawing pass, the sample is returned to the furnace for annealing at 160-300°C. As the number of drawing passes increases, the annealing temperature after each drawing pass gradually decreases. More preferably, the annealing temperature after the first drawing pass is 285-300°C. The annealing time for a single pass is 60-120 min. Even more preferably, the annealing atmosphere is argon. The total number of drawing passes is 15; the annealing temperature after each drawing pass gradually decreases, from 300°C for the first pass to 160°C for the final pass, i.e., the annealing temperature gradient between each pass is 10°C. The low-temperature annealing after each drawing pass makes dislocation recovery difficult and recrystallization incomplete, resulting in a certain proportion of bimodal microstructure. On the other hand, the lower annealing temperature can prevent grain growth, which is more conducive to subsequent room temperature drawing and the final acquisition of bimodal microstructure. This microstructure not only achieves higher strength but also improves the product's anti-aging ability. Preferably, the aging treatment process in step S3 is as follows: aging temperature of 25-150℃, holding time of 5-20 hours, using air cooling or water cooling.

[0030] As a further preferred option, the aging temperature is 110–140℃, and the holding time is 8–12 hours.

[0031] As a further preferred option, the aging temperature is 120℃, the holding time is 10 hours, the protective atmosphere is argon, and air cooling is used after the aging treatment is completed.

[0032] Preferably, the surface modification method in step S4 is passivation treatment.

[0033] In this invention, the anti-aging ability of the alloy is referenced by the change in its tensile strength and uniform elongation after being placed at room temperature for 5 months.

[0034] In industrial applications, aged zinc alloys are polished sequentially with 200, 600, 1000, 1500, 2000, 3000, and 5000 grit sandpaper, followed by electrochemical polishing to achieve a surface roughness Ra≤3.2. Surface modification is then performed, specifically passivation. The operation steps include: (1) Cleaning treatment. Chemical cleaning is used to remove surface impurities, ensuring a clean surface. (2) Pickling treatment. Acetic acid is used to remove oxides and other impurities from the zinc alloy surface for 3-5 minutes. (3) Neutralization treatment. A soda solution is used to neutralize the acidic substances remaining on the zinc alloy surface for 3-5 minutes. (4) Passivation treatment. Chromic acid is used for passivation, forming a passivation film on the surface for 10-15 minutes. (5) Cleaning and drying. After cleaning the zinc alloy surface with water, it is dried in a 40°C drying oven. The surface modification method described above improves the appearance of zinc alloy surfaces, increases corrosion resistance, and extends service life.

[0035] The high work hardening rate of the zinc alloy in this invention benefits from the bimodal structure generated by the alternating distribution of ultrafine recrystallized grains and coarse deformed grains. The coarse grains are more prone to uniform twinning deformation, playing a good role in coordinating deformation during intergranular transfer. Furthermore, by changing the crystal orientation, they stimulate further crystal slip, thereby improving the strength and work hardening rate of the Zn alloy. The proportion of recrystallized grains is within 55-65%. Secondly, due to the significant difference in atomic radius and electronegativity between Ti / Y and Zn, adding Ti and Y to the Zn-Cu-Al matrix can precipitate TiZn. 15 and YZn 11 Phase particles, by controlling the size distribution of the precipitated phase, yield TiZn with a multi-level size distribution. 15 and YZn 11The micron-sized particles in the zinc alloy, due to their particle-promoting effect, can act as nucleation sites for recrystallization, resulting in grain refinement. Meanwhile, the nano-sized particles effectively suppress grain boundary slip during deformation, enhancing material strength. Therefore, through the synergistic effect of the bimodal structure and multi-sized Y- and Ti-rich phase particles of this invention, the zinc alloy achieves a combination of high strength and toughness with a high work hardening rate.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] (1) Based on suitable alloying elements and proportions, the present invention improves the microstructure of Zn alloy by adding Cu, Al, Ti and Y elements. Under the combined synergistic effect of the bimodal structure with alternating coarse and fine grains and multi-level Y-rich and Ti-rich phase particles, it has high plastic deformation capacity. Its uniform elongation reaches 23-35% and its tensile strength reaches 450-515MPa, effectively avoiding the phenomenon of Zn alloy implants breaking at local positions due to excessive deformation.

[0038] (2) In this invention, the significant advantage of adding 0.3-1% Cu and 0.2-0.5% Al is that while improving strength, it can greatly improve the thermal stability of the Zn matrix. After being placed at room temperature for 3 months, the decrease in tensile strength and uniform elongation is less than or equal to 2.5% (after optimization, even after 5 months, the change in tensile strength and uniform elongation is less than 1.5%), which effectively avoids the phenomenon of Zn alloy implants breaking due to excessive deformation in local positions. Therefore, it has excellent anti-aging ability.

[0039] (3) The total content of alloying elements in the medical zinc alloy of the present invention does not exceed 2%. While having good biocompatibility, it has a low preparation cost through a relatively common processing method of alternating hot extrusion, drawing deformation and low temperature annealing. Attached Figure Description

[0040] Figure 1 A flowchart illustrating the preparation process of Zn-Cu-Al-Ti-Y alloy provided in this embodiment of the invention.

[0041] Figure 2 This is a microstructure diagram of the product obtained in Example 1.

[0042] Figure 3 TiZn in the product obtained in Example 1 15 YZn 11 Morphology diagram of phase particles.

[0043] from Figure 1 The basic preparation process of this invention can be seen.

[0044] Figure 2Combination Figure 3 It can be seen that the zinc alloy forms a bimodal grain structure and contains TiZn of multiple sizes. 15 Phase particle and size multi-level YZn 11 Phase particles, the multi-level TiZn 15 Phase particles include nano-sized TiZn 15 Phase particles, submicron TiZn 15 Phase particles, micron-sized TiZn 15 Phase particles, multi-level YZn 11 Phase particles include nano-sized YZn 11 Phase particles, submicron-sized YZn 11 Phase particles, micron-sized YZn 11 Phase particles. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to some specific embodiments. Of course, these are merely examples and are not intended to limit the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this invention. These all fall within the scope of protection of this invention.

[0046] Example 1

[0047] This embodiment is a medical biodegradable Zn-Cu-Al-Ti-Y zinc alloy, with the following elemental mass fractions: Cu: 1%, Al: 0.45%, Ti: 0.45%, Y: 0.09%, and the balance being Zn.

[0048] The preparation method of the biodegradable zinc alloy in this embodiment is as follows:

[0049] (1) Batching: Weigh the ingredients according to the above composition. It should be noted that each element has different burn-off rates during the smelting process. Weigh the ingredients according to the burn-off rates of 3% for zinc, 1% for copper, 1% for aluminum, 5% for titanium, and 9% for yttrium.

[0050] (2) Smelting: Zinc-copper master alloy (the mass ratio of metallic copper and zinc is 1:99, and after being mixed and melted at 650℃, the molten liquid is poured into an intermediate grinding mold at a grinding mold temperature of 180℃ and then cooled to room temperature naturally), copper-titanium master alloy (the mass ratio of metallic titanium and copper is 95.5:4.5, and after being mixed and melted at 1120℃, the molten liquid is poured into an intermediate grinding mold and then cooled to room temperature naturally), and zinc-yttrium master alloy ingot (the mass ratio of metallic zinc and yttrium is 98.5:1.5, and after being mixed and melted at 790℃, the molten liquid is poured into an intermediate grinding mold at a grinding mold temperature of 480℃ and then cooled to room temperature naturally). Then, pure zinc ingots, pure aluminum ingots, zinc-copper master alloys, copper-titanium master alloys, and zinc-yttrium master alloys are smelted in a vacuum induction melting furnace with a ratio of Cu: 1%, Al: 0.45%, Ti: 0.45%, Y: 0.09%, and the balance being Zn. The protective atmosphere is argon. The molten metal is then poured into a cylindrical inner cavity at 200°C at 560°C and gradually cooled to room temperature to form a zinc alloy ingot.

[0051] Homogenization treatment: First, the surface layer of the above-mentioned ingot blank is removed by machining to obtain a cylindrical ingot blank with a diameter of Φ55mm. Then, the cast zinc alloy ingot is kept at 290℃ in an argon protective atmosphere for 3 hours, then heated to 330℃ and kept at 330℃ for 6 hours, and then cooled in water to room temperature to improve the segregation of elements in the zinc alloy.

[0052] Hot extrusion: The extrusion ratio is 22:1, the extrusion temperature is 250℃, and a layer of graphite is uniformly covered on the surface of the die as a lubricant before extrusion. After extrusion, an alloy wire with a diameter of Φ11.6mm is obtained.

[0053] Drawing and Low-Temperature Annealing: Room temperature drawing not only avoids the impact of high-temperature deformation on the material structure, but also boasts high production efficiency, low energy consumption, and a good surface finish. During the drawing process, a sulfurized fatty acid ester coolant is used for surface cooling and lubrication. The drawing speed is 20–30 mm / s. After each drawing pass, the surface residue is thoroughly cleaned, and the wire is then placed in an furnace for annealing at 160–300°C for 1.5 hours in an argon atmosphere. The total number of drawing passes is 15, resulting in zinc alloy wires with a diameter of Φ1.9–2.1 mm. The annealing temperature gradually decreases after each drawing pass, from 300°C in the first pass to 160°C in the final pass, representing a 10°C temperature gradient between each pass.

[0054] Aging treatment: The aging temperature is 120℃, the holding time is 10 hours, the protective atmosphere is argon, and air cooling is used after the aging treatment is completed.

[0055] Surface modification: After the aged zinc alloy wire is laser-cut, it is polished sequentially with 200, 600, 1000, 1500, 2000, 3000, and 5000 grit sandpaper, and then electrochemically polished to make the surface roughness Ra≤3.2. Surface modification is then performed, and the surface modification method is passivation. The operation steps include: (1) Cleaning treatment. Chemical cleaning is used to remove impurities from the surface to ensure that the surface is clean. (2) Pickling treatment. Acetic acid is used to remove oxides and other impurities from the zinc alloy surface for 3 to 5 minutes. (3) Neutralization treatment. Sodium hydroxide solution is used to neutralize the acidic substances remaining on the zinc alloy surface for 3 to 5 minutes. (4) Passivation treatment. Chromic acid is used for passivation to form a passivation film on the surface for 10 to 15 minutes. (5) Cleaning and drying. After cleaning the zinc alloy surface with clean water, it is placed in a drying oven at 40°C for drying. The surface modification method described above improves the appearance of zinc alloy surfaces, increases corrosion resistance, and extends service life.

[0056] The zinc alloy obtained by this process exhibits the following mechanical properties: tensile strength of 511 MPa and uniform elongation of 35%. Furthermore, the alloy demonstrates strong resistance to aging; after 5 months at room temperature, the changes in tensile strength and uniform elongation are both within 1.5%. Because the total alloying element content of this zinc alloy is less than 2%, the solid solution strengthening effect of low-content copper and aluminum in the zinc matrix is ​​fully utilized, while the appropriate addition of titanium and yttrium fully leverages the advantages of grain refinement and second-phase strengthening. The high strength and uniform elongation of this alloy are also attributed to the bimodal structure of alternating coarse and fine grains and the synergistic effect of multi-level Y-rich and Ti-rich phase particles. Specifically, the proportion of fine grains is within 55-65%, and multi-level TiZn particles are dispersed in the zinc matrix. 15 and YZn 11 The micron-sized particles in this invention act as recrystallization nuclei due to the particle-promoting effect, resulting in grain refinement. Meanwhile, the nano-sized particles effectively suppress grain boundary slip during deformation, enhancing material strength. Therefore, through the synergistic effect of the bimodal structure and multi-sized Y- and Ti-rich phase particles of this invention, the zinc alloy achieves a combination of high strength and toughness with a high work hardening rate, effectively preventing fractures in zinc alloy implants due to excessive deformation at localized locations. Furthermore, the solidification of a certain amount of high-melting-point copper and trace amounts of titanium and yttrium in the low-melting-point zinc matrix significantly improves the thermal stability of the Zn matrix, thereby greatly enhancing the anti-aging properties of the Zn alloy. Therefore, its superior performance meets the mechanical performance requirements for cardiovascular stent applications.

[0057] Example 2

[0058] This embodiment is a medical biodegradable Zn-Cu-Al-Ti-Y zinc alloy, with the following elemental mass fractions: Cu: 0.5%, Al: 0.3%, Ti: 0.25%, Y: 0.05%, and the balance being Zn. Other steps are the same as in Specific Embodiment 1.

[0059] The zinc alloy obtained under this process has the following mechanical properties: tensile strength of 457 MPa and uniform elongation of 29%. After being placed at room temperature for 5 months, the changes in tensile strength and uniform elongation were 2.2% and 2.3%, respectively, indicating strong anti-aging ability. Therefore, its excellent performance can meet the mechanical performance requirements for cardiovascular stent applications.

[0060] Example 3

[0061] This embodiment provides a medical biodegradable Zn-Cu-Al-Ti-Y zinc alloy, with the following elemental mass fractions: Cu: 1%, Al: 0.45%, Ti: 0.45%, Y: 0.09%, and the balance being Zn.

[0062] In this comparative example, the difference from Specific Example 1 is the hot extrusion process; all other processes are the same. The specific hot extrusion process in this comparative example is as follows: the extrusion ratio is 25:1, the extrusion temperature is 280℃, a layer of graphite is uniformly coated on the surface of the die as a lubricant before extrusion, and an alloy wire with a diameter of Φ12.6mm is obtained after extrusion.

[0063] The zinc alloy obtained by this process has the following mechanical properties: tensile strength of 502 MPa and uniform elongation of 23%. After being placed at room temperature for 5 months, the changes in tensile strength and uniform elongation are approximately 1.9% and 2.3%, respectively.

[0064] Example 4

[0065] This embodiment provides a medical biodegradable Zn-Cu-Al-Ti-Y zinc alloy, with the following elemental mass fractions: Cu: 1%, Al: 0.45%, Ti: 0.45%, Y: 0.09%, and the balance being Zn. The difference between this comparative example and Specific Example 1 lies in the aging treatment process. Specifically, the aging temperature is 200℃, the holding time is 10 hours, and air cooling is used.

[0066] The zinc alloy obtained by this process has the following mechanical properties: tensile strength of 456 MPa and uniform elongation of 29%. After being placed at room temperature for 5 months, the changes in tensile strength and uniform elongation are approximately 2.3% and 2.5%, respectively.

[0067] Comparative Example 1

[0068] This comparative example is a medical biodegradable Zn-Cu-Al-Ti-Y zinc alloy with the following elemental mass fractions: Cu: 1%, Al: 0%, Ti: 0.45%, Y: 0.09%, and the balance being Zn. Other steps are the same as in Specific Example 1.

[0069] The zinc alloy obtained by this process has the following mechanical properties: tensile strength of 395 MPa and uniform elongation of 31%. This alloy exhibits strong resistance to aging; after being placed at room temperature for 5 months, the changes in tensile strength and uniform elongation are approximately 2.6% and 2.1%, respectively. Compared to the alloy described in Example 1, this alloy does not contain Al, resulting in a weakened solid solution strengthening effect and a significant reduction in the alloy's mechanical strength.

[0070] Comparative Example 2

[0071] This comparative example is a medical biodegradable Zn-Cu-Al-Ti-Y zinc alloy with the following elemental mass fractions: Cu: 1%, Al: 0.45%, Ti: 0%, Y: 0%, and the balance being Zn. Other steps are the same as in Specific Example 1.

[0072] The zinc alloy obtained by this process has the following mechanical properties: tensile strength of 387 MPa and uniform elongation of 36%. This alloy exhibits strong resistance to aging; after being placed at room temperature for 5 months, its tensile strength and uniform elongation decreased by approximately 2.3% and 2.5%, respectively. Compared to the alloy described in Example 1, this alloy does not contain titanium and yttrium, resulting in a significant reduction in the number of precipitated second-phase particles and a marked weakening of the second-phase strengthening effect, thereby reducing the alloy's mechanical strength.

[0073] Comparative Example 3

[0074] This comparative example is a medical biodegradable Zn-Cu-Al-Ti-Y zinc alloy with the following elemental mass fractions: Cu: 1%, Al: 0%, Ti: 0%, Y: 0%, and the balance being Zn. Other steps are the same as in Specific Example 1.

[0075] The zinc alloy obtained by this process has the following mechanical properties: tensile strength of 305 MPa and uniform elongation of 32%. This alloy exhibits strong resistance to aging; after being placed at room temperature for 5 months, the changes in tensile strength and uniform elongation are approximately 2.1% and 2.2%, respectively. Compared to the alloy described in Example 1, this alloy does not contain titanium and yttrium, resulting in a significant reduction in the number of precipitated second-phase particles and a marked weakening of the second-phase strengthening effect, thereby reducing the alloy's mechanical strength.

[0076] Comparative Example 4

[0077] This comparative example describes a biodegradable Zn-Cu-Al-Ti-Y zinc alloy for medical use, prepared with the following elemental mass fractions: Cu: 0.3%, Al: 0.2%, Ti: 0.0%, Y: 0.01%, and the balance Zn. Preferably, the alloy elemental mass fractions are Cu: 0.3%, Al: 0.2%, Ti: 0.2%, Y: 0.01%, and the balance Zn. Other steps are the same as in Specific Example 1.

[0078] The zinc alloy obtained by this process has the following mechanical properties: tensile strength of 403 MPa and uniform elongation of 19%. Furthermore, the alloy exhibits strong anti-aging properties; after 5 months at room temperature, its tensile strength and uniform elongation changed by only 3.1% and 3.6%, respectively. Therefore, the tensile strength of this alloy meets the performance requirements for cardiovascular stent applications, but its lower plasticity limits its application range.

[0079] Comparative Example 5

[0080] This comparative example provides a medical biodegradable Zn-Cu-Al-Ti-Y zinc alloy with the following elemental mass fractions: Cu: 1%, Al: 0.45%, Ti: 0.45%, Y: 0.09%, and the balance being Zn.

[0081] In this comparative example, the difference from Specific Example 1 is that low-temperature annealing is performed only after the final drawing process, and the annealing process is to hold at 160°C for 1.5 hours. The other steps are the same as in Example 1.

[0082] The zinc alloy obtained by this process has the following mechanical properties: tensile strength of 496 MPa and uniform elongation of 17%. After being placed at room temperature for 5 months, the changes in tensile strength and uniform elongation were 4.2% and 4.6%, respectively.

[0083] Table 1 compares the room temperature tensile strength and uniform elongation of Examples 1-4 and Comparative Examples 1-5, as well as the experimental results of their anti-aging ability evaluation after being placed at room temperature for 5 months.

[0084] Table 1 shows the experimental results of tensile strength, uniform elongation, and anti-aging ability assessment after 5 months of storage at room temperature for the examples and comparative examples:

[0085]

[0086]

[0087] As can be seen from Examples 1-4 and Comparative Examples 1-5, the Zn-Cu-Al-Ti-Y alloy material of the present invention has a relatively simple preparation process. Through reasonable alloying and subsequent preparation processes, a bimodal structure with alternating coarse and fine grains and multi-level Y-rich and Ti-rich phase particles are obtained, which effectively improves the strength of the alloy and enhances its work hardening ability. It has a high uniform elongation rate, which can ensure the mechanical performance requirements and safety of cardiovascular stent applications. At the same time, after being placed at room temperature for 5 months, the change in mechanical properties of the alloy is within 2.5% (which can reach 1.4% after optimization), and it has excellent anti-aging ability. It is an in vivo biodegradable medical zinc alloy material with anti-aging and high strength and toughness.

[0088] The specific embodiments and comparative examples of the present invention have been described above to facilitate a detailed understanding of the technical solutions of the present invention, but should not be construed as limiting the scope of protection of the invention patent. Those skilled in the art should understand that the present invention is not limited to the specific embodiments described above, and various modifications or variations can be made within the scope of the claims, all of which fall within the protection scope of the present invention. It should be understood that technical solutions obtained by those skilled in the art based on the technical solutions provided by the present invention through logical analysis, reasoning, or limited experimentation are all within the protection scope of the appended claims. Therefore, the scope of protection of this invention patent should be determined by the content of the appended claims, and the specification can be used to interpret the content of the claims.

Claims

1. An anti-aging medical biodegradable zinc alloy, characterized in that: The alloy, by weight percentage, comprises the following elements: Cu 0.1~1%, Al 0.1~0.5%, Ti 0~0.5%, Y 0.01~0.1%, with the balance being Zn; The zinc alloy forms a bimodal grain structure and contains TiZn of multiple sizes. 15 Phase particle and size multi-level YZn 11 Phase particles, the multi-level TiZn 15 Phase particles include nano-sized TiZn 15 Phase particles, submicron TiZn 15 Phase particles, micron-sized TiZn 15 Phase particles, multi-level YZn 11 Phase particles include nano-sized YZn 11 Phase particles, submicron-sized YZn 11 Phase particles, micron-sized YZn 11 Phase particles; The alloy is prepared by the following steps: S1: Prepare the raw materials according to the alloy composition design. S2: The prepared raw materials are smelted and cast to obtain as-cast zinc alloy ingots. S3: After homogenization treatment, the cast zinc alloy ingot is hot-extruded. The extruded zinc alloy is subjected to multiple cold drawing and low-temperature annealing alternating processes. Finally, medical biodegradable Zn-Cu-Al-Ti-Y alloys with different property combinations are obtained through aging treatment. The hot extrusion deformation temperature is 200~300 ℃, the extrusion ratio is 15~25:1, and the drawing speed is 20~30 mm / s. The low-temperature annealing temperature is 160~300℃, the number of drawing cycles is greater than or equal to 8, and the annealing temperature after the first drawing is the highest, decreasing thereafter. The aging temperature is 25~200℃. S4: The biodegradable zinc alloy wire is laser-cut into shape, polished with sandpaper and electrochemically, and then surface modified. The surface modification method is selected from one or more of surface carburizing, sandblasting, and passivation.

2. The anti-aging medical biodegradable zinc alloy according to claim 1, characterized in that: The alloy, by weight percentage, comprises the following elements: Cu 0.3~1%, Al 0.2~0.5%, Ti 0~0.5%, Y 0.01~0.1%, with the balance being Zn.

3. The anti-aging medical biodegradable zinc alloy according to claim 2, characterized in that: The sum of the mass percentages of Cu, Al, Ti, and Y is less than or equal to 2%.

4. The anti-aging medical biodegradable zinc alloy according to claim 3, characterized in that: The alloy, by weight percentage, comprises the following elements: Cu 0.5-1%, Al 0.3-0.5%, Ti 0.2-0.5%, Y 0.05-0.1%, with the balance being Zn.

5. The anti-aging medical biodegradable zinc alloy according to claim 4, characterized in that: The alloy, by weight percentage, comprises Cu: 0.5%, Al: 0.3%, Ti: 0.25%, Y: 0.05%, with the balance being Zn; or the alloy, by weight percentage, comprises Cu: 1%, Al: 0.45%, Ti: 0.45%, Y: 0.09%, with the balance being Zn.

6. The anti-aging medical biodegradable zinc alloy according to claim 1, characterized in that: The extrusion ratio in S3 is 21~25:

1.

7. The anti-aging medical biodegradable zinc alloy according to claim 1, characterized in that: The temperature of the smelting process in step S2 is 560~1120 ℃; The homogenization process in step S3 is as follows: vacuum insulation or isostatic pressing with inert gas at 1~50MPa for 5~15 h at a temperature of 120~400 ℃, followed by rapid water cooling to obtain a supersaturated solid solution.

8. The anti-aging medical biodegradable zinc alloy according to claim 7, characterized in that: Homogenization treatment: First, the surface layer of the cast zinc alloy ingot is removed by machining. Then, the cast zinc alloy ingot is kept at 280~300℃ in an argon protective atmosphere for 2~4 hours, then heated to 320~340℃ and kept at 4~8 hours, and then cooled to room temperature in water. The hot extrusion deformation process in step S3 has a temperature of 240~260℃ and an extrusion ratio of 21~23:

1. Before extrusion, a layer of graphite is uniformly covered on the surface of the mold as a lubricant. The aging process in step S3 is as follows: the aging temperature is 25-150℃, the holding time is 5-20 hours, and air cooling or water cooling is used.

9. The anti-aging medical biodegradable zinc alloy according to claim 8, characterized in that: The specific drawing process in step S3 is as follows: drawing at room temperature, drawing speed of 20~40 mm / s, total number of drawing passes of 13-18, after each drawing pass, it is placed back in the furnace for annealing at 160~300 ℃. As the number of drawing passes increases, the annealing temperature after each drawing pass gradually decreases.

10. The anti-aging medical biodegradable zinc alloy according to claim 9, characterized in that: The annealing temperature after the first drawing is 285~300℃; the annealing time for a single annealing is 60-120min.

11. The anti-aging medical biodegradable zinc alloy according to claim 9, characterized in that: The annealing atmosphere is argon.

12. The anti-aging medical biodegradable zinc alloy according to claim 9, characterized in that: The total number of drawing passes is 15. The annealing temperature gradually decreases after each drawing pass, from 300 ℃ in the first pass to 160 ℃ in the last pass, that is, the annealing temperature gradient between each pass is 10 ℃.

13. The anti-aging medical biodegradable zinc alloy according to claim 8, characterized in that: The aging temperature is 110~140℃, and the heat preservation time is 8~12 hours.

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