A high-strength, high-ductility, low-alloying-element-content Zn-Mn-Mg-Sr alloy

Abstract

This invention discloses a high-strength, high-ductility, low-alloy element Zn-Mn-Mg-Sr alloy, comprising, by mass percentage: Mn 0.23%–0.5%, Mg 0.05%–0.1%, Sr 0.02%–0.1%, with the balance being Zn; and the total content of Mn, Mg, and Sr is 0.3%–0.7%. Furthermore, this invention discloses a method for preparing this alloy: 1. Smelting; 2. Homogenization heat treatment; 3. Extrusion; 4. Multi-pass rotary forging; 5. Stabilization annealing. This invention uses fewer alloying elements, all of which have biological functions, resulting in lower raw material costs and higher biocompatibility. Through multi-directional plastic deformation and stabilization annealing, the alloy exhibits stable microstructure and mechanical properties, with a tensile strength greater than 300 MPa, a yield strength greater than 200 MPa, an elongation at fracture greater than 30%, and a reduction of area greater than 60%, making it suitable for applications in implantable and interventional medical devices.

Description

Technical Field

[0001] This invention belongs to the field of medical non-ferrous metal materials technology, specifically relating to a high-strength, high-ductility, low-alloy element content Zn-Mn-Mg-Sr alloy. Background Technology

[0002] Traditional medical metals (titanium alloys, cobalt-chromium alloys, etc.) are widely used in clinical practice because they provide sufficient mechanical support. However, the long-term retention of these metals in the body can be detrimental to tissue healing. Therefore, biodegradable metal materials that can promote tissue healing and do not remain in the body after healing have attracted much attention. Zinc is one such biodegradable metal, but pure zinc has too low strength. It does not meet the mechanical properties required for medical applications: yield strength (YS) greater than 200 MPa, ultimate tensile strength (UTS) greater than 300 MPa, and elongation after fracture (A) greater than 20%.

[0003] Alloying is the main method to improve the mechanical properties of zinc alloys. Al and Cu are the main alloying elements in industrial zinc alloys, which can significantly improve the mechanical properties of zinc alloys. The alloying elements in medical zinc alloys must be non-toxic to the human body; commonly added elements include Mg, Ca, Li, Fe, Li, and Ag, limiting the selection range. At the same time, excessive alloying elements can significantly increase the uneven degradation of zinc alloys. Mn is a component and activator of many enzymes and an important element in bone formation, promoting osteoblast differentiation and preventing osteoporosis. Mg is one of the essential elements for the human body, participating in the reactions of many enzymes and being an important component of bones. Sr is an essential trace element that promotes bone development and growth, and helps in the repair and regeneration of bone tissue. Sr has a protective effect on the cardiovascular system, regulating the function of vascular endothelial cells, increasing the elasticity and stability of blood vessels, and reducing the risk of atherosclerosis.

[0004] Furthermore, alloying combined with plastic deformation can further improve the mechanical properties of zinc alloys. However, current technologies make it difficult to achieve high strength and high ductility in zinc alloys with low alloying element additions. Moreover, most zinc alloys with high mechanical properties are currently in a plastic deformation state, resulting in unstable mechanical properties and adversely affecting degradation performance.

[0005] Therefore, there is a need for medical zinc alloys with low alloy element content and stable high strength and high plasticity properties, as well as their preparation methods. Summary of the Invention

[0006] The technical problem to be solved by this invention is to address the shortcomings of the prior art by providing a high-strength, high-ductility, low-alloying-element Zn-Mn-Mg-Sr alloy. This alloy contains only three alloying elements, and the total amount of these elements is relatively low, ranging from 0.3% to 0.7%. This results in lower raw material costs, higher biocompatibility, and the fact that Mn, Mg, and Sr are all essential nutrients for the human body with biological functions. The Zn-Mn-Mg-Sr alloy exhibits stable high strength and high ductility, making it suitable for applications in implantable and interventional medical devices.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a high-strength, high-ductility, low-alloy element content Zn-Mn-Mg-Sr alloy, characterized in that the chemical composition of the Zn-Mn-Mg-Sr alloy, by mass percentage, is: Mn 0.23%~0.5%, Mg 0.05%~0.1%, Sr 0.02%~0.1%, with the balance being Zn; and the total content of Mn, Mg and Sr is 0.3%~0.7%;

[0008] The preparation method of the Zn-Mn-Mg-Sr alloy includes the following steps:

[0009] Step 1: Melt zinc granules, manganese flakes, magnesium blocks, and strontium blocks to obtain alloy ingots;

[0010] Step 2: The alloy ingot obtained in Step 1 is subjected to homogenization heat treatment to obtain a heat-treated ingot.

[0011] Step 3: Extrude the heat-treated ingot obtained in Step 2 to obtain extruded bars;

[0012] Step 4: Perform multiple passes of rotary forging on the extruded bar obtained in Step 3 to obtain rotary forged bar.

[0013] Step 5: Stabilize and anneal the forged bar obtained in Step 4 to obtain a Zn-Mn-Mg-Sr alloy.

[0014] This invention designs the composition of a Zn-Mn-Mg-Sr alloy, where the addition of Mn primarily improves the alloy's plasticity, the addition of Mg primarily improves the alloy's strength, and the addition of Sr refines the grains, thereby improving the alloy's mechanical properties. It also enhances the alloy's osteogenic properties, high-temperature stability, and oxidation resistance. Furthermore, it contains only three alloying elements: Mn, Mg, and Sr. This fewer element types, coupled with the fact that Mn, Mg, and Sr are all essential nutrients for the human body and possess biological functions, result in higher biocompatibility. Additionally, by controlling their content and maintaining the total content at 0.3%–0.7%, trace additions are achieved, avoiding the formation of excessive second phases, reducing plasticity, minimizing localized corrosion, and lowering raw material costs.

[0015] This invention first melts zinc granules, manganese flakes, magnesium blocks, and strontium blocks to mix the four elements and obtain an alloy ingot. Then, homogenization heat treatment is used to eliminate component segregation in the alloy ingot, ensuring the uniformity of the Zn-Mn-Mg-Sr alloy composition. Extrusion is used to control the dimensions and give the Zn-Mn-Mg-Sr alloy the best mechanical properties. Multi-pass rotary forging is used to increase the recrystallization ratio, refine the grains, and weaken the basal texture, significantly improving the strength and plasticity of the Zn-Mn-Mg-Sr alloy. Stabilization annealing is used to keep the microstructure and mechanical properties of the Zn-Mn-Mg-Sr alloy in a stable state, making them less prone to change.

[0016] The above method is characterized in that the smelting process in step one is as follows: zinc granules are placed in a crucible, heated to 650℃~680℃, and after the zinc granules are completely melted, manganese sheets and strontium blocks are pressed in, while argon gas is introduced for protection and the temperature is maintained for 40min~60min, during which time the mixture is stirred 3~5 times. Then, magnesium blocks are pressed in, and the temperature is maintained for 15min~20min, followed by stirring. After slag removal and filtration, the mixture is cast into a graphite mold and cooled to room temperature. In this invention, manganese sheets and strontium blocks are pressed into the zinc melt in batches, followed by magnesium blocks. Because manganese and strontium have high melting points and require a longer time to melt into the zinc melt, they need to be added first. Magnesium, whose melting point is less different from that of zinc, does not require a long time to melt into the zinc melt, so it is added later. This controls the overall smelting time, reduces the loss of alloying elements, and avoids the possibility of excessive local reactions of alloying elements, thereby controlling the accurate composition.

[0017] The aforementioned high-strength, high-ductility, low-alloy element content Zn-Mn-Mg-Sr alloy is characterized in that, in step one, the zinc granules have a purity of not less than 99.99%, the manganese sheets have a purity of not less than 99.99%, the magnesium blocks have a purity of not less than 99.99%, and the strontium blocks have a purity of not less than 99.95%. This invention controls the purity of the raw materials and thus the purity of the Zn-Mn-Mg-Sr alloy, thereby ensuring the performance of the Zn-Mn-Mg-Sr alloy.

[0018] The above method is characterized in that the homogenization heat treatment process in step two is as follows: heating to 345℃~355℃ in a vacuum environment at a heating rate of 5℃ / min~12℃ / min, holding at that temperature for 11.5h~12.5h, and then cooling in the furnace to below 50℃ followed by air cooling. This invention, by controlling the homogenization heat treatment process, ensures that the alloy ingot reaches the set temperature in the furnace, thereby accurately controlling the holding time and effectively eliminating component segregation in the alloy ingot.

[0019] The above method is characterized in that the extrusion process in step three is as follows: first, the surface of the zinc alloy ingot is machined to remove the riser and oxide scale; then, it is heated to 195℃~205℃ and held for 40min~60min; then, extrusion is performed at an extrusion cylinder temperature of 190℃~200℃, an extrusion ratio of 16:1, and an extrusion speed of 22mm / s~28mm / s. This invention controls the dimensions by controlling the extrusion process, thus giving the Zn-Mn-Mg-Sr alloy the best mechanical properties.

[0020] The above method is characterized in that the multi-pass rotary forging in step four is carried out at room temperature, and the deformation amount of each pass is 10.6% to 18.3%, with a total deformation amount exceeding 50%. This invention, by controlling the multi-pass rotary forging process, increases the recrystallization ratio, refines the grains, and weakens the basal texture, thereby significantly improving the strength and plasticity of Zn-Mn-Mg-Sr alloys.

[0021] The above method is characterized in that the stabilization annealing process in step five is as follows: under vacuum conditions, the furnace temperature is raised to 195℃~205℃, held for 15min~25min, and then cooled for 30min~40min before being removed from the furnace. This invention, by controlling the stabilization annealing process, ensures that the microstructure and mechanical properties of the Zn-Mn-Mg-Sr alloy remain stable and do not undergo significant changes under storage and operating temperature conditions.

[0022] The above method is characterized in that the mechanical properties of the Zn-Mn-Mg-Sr alloy in step five are: tensile strength greater than 300 MPa, yield strength greater than 200 MPa, elongation after fracture greater than 30%, and reduction of area greater than 60%.

[0023] The aforementioned high-strength, high-ductility, low-alloy-element-content Zn-Mn-Mg-Sr alloy is characterized in that the Zn-Mn-Mg-Sr alloy described in step five is applied in the field of implantable and interventional medical devices. This invention provides a method for preparing a stable, high-strength, and high-ductility Zn-Mn-Mg-Sr alloy with low alloy-element content to meet the application needs of zinc alloys in implantable and interventional medical devices. Furthermore, another objective of this invention is that the Zn-Mn-Mg-Sr alloy rods can be used to manufacture products such as bone screws and vascular stents.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] 1. The Zn-Mn-Mg-Sr alloy of the present invention has few alloying elements, only 3, and the total amount of alloying elements is relatively small, only 0.3% to 0.7%. The raw material cost is low, the biosafety is higher, and Mn, Mg and Sr are all essential nutrients for the human body and have biological functions.

[0026] 2. This invention uses extrusion and multi-pass rotary forging to perform multi-directional plastic deformation, refine the microstructure, and improve the strength and plasticity of the zinc alloy. After plastic deformation, stabilizing annealing is performed to stabilize the microstructure and mechanical properties of the Zn-Mn-Mg-Sr alloy, making them less prone to change. The mechanical properties of the Zn-Mn-Mg-Sr alloy are: tensile strength greater than 300MPa, yield strength greater than 200MPa, elongation after fracture greater than 30%, and reduction of area greater than 60%, achieving the characteristics of stable high strength and high plasticity.

[0027] 3. The preparation steps of this invention are all common processing methods, which are suitable for high-efficiency and low-cost mass production. The resulting Zn-Mn-Mg-Sr alloy can be used in the field of implantable and interventional medical devices.

[0028] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0029] Figure 1 This is a phase distribution diagram of the rotary forged bar in Embodiment 1 of the present invention.

[0030] Figure 2 This is a phase distribution diagram of the Zn-0.5Mn-0.1Mg-0.1Sr alloy obtained in Example 1 of the present invention.

[0031] Figure 3 This is a diagram of the core average orientation difference (KAM) of the rotary forged bar in Embodiment 1 of the present invention.

[0032] Figure 4 This is the core average orientation difference (KAM) diagram of the Zn-0.5Mn-0.1Mg-0.1Sr alloy obtained in Example 1 of this invention.

[0033] Figure 5 This is a high-magnification microstructure image of the rotary forged bar material in Embodiment 1 of the present invention.

[0034] Figure 6 This is a high-magnification microstructure of the Zn-0.5Mn-0.1Mg-0.1Sr alloy obtained in Example 1 of the present invention.

[0035] Figure 7 The stress-strain curves are forged bars and Zn-0.5Mn-0.1Mg-0.1Sr alloys prepared in Example 1 and Zn-0.5Mn alloys prepared in Comparative Example 1. Detailed Implementation

[0036] Example 1

[0037] This embodiment includes the following steps:

[0038] Step 1: Prepare the ingredients according to Zn-0.5Mn-0.1Mg-0.1Sr. Add zinc granules with a purity of not less than 99.99% to a crucible and heat it to 680℃. After the zinc granules are completely melted, press in manganese flakes with a purity of not less than 99.99% and strontium blocks with a purity of not less than 99.95%. At the same time, argon gas is introduced for protection and the temperature is maintained for 60 minutes, during which time it is stirred 4 times. Then, press in magnesium blocks with a purity of not less than 99.99% and maintain the temperature for 15 minutes, then stir. After slag removal and filtration, pour the mixture into a graphite mold and cool it to room temperature to obtain an alloy ingot.

[0039] Step 2: Heat the alloy ingot obtained in Step 1 to 350°C in a vacuum environment at a heating rate of 10°C / min, hold for 12 hours, then cool with the furnace to less than 50°C and air cool to obtain a heat-treated ingot.

[0040] Step 3: First, the surface of the heat-treated ingot obtained in Step 2 is machined to remove the riser and oxide scale. Then, it is heated to 200℃ and held for 60 minutes. Then, it is extruded at an extrusion cylinder temperature of 195℃, an extrusion ratio of 16:1, and an extrusion speed of 25mm / s to obtain an extruded bar with a diameter of 12.5mm.

[0041] Step 4: The extruded bar obtained in Step 3 is subjected to multi-pass rotary forging at room temperature, with a deformation amount of 10.6% to 18.3% per pass and a total deformation amount of 58%, to obtain a rotary forged bar.

[0042] Step 5: Under vacuum conditions, heat the forged bar obtained in Step 4 to 200°C in a furnace and hold for 20 minutes. Then, cool it in the furnace for 40 minutes before removing it from the furnace to obtain the Zn-0.5Mn-0.1Mg-0.1Sr alloy.

[0043] The chemical composition of the Zn-0.5Mn-0.1Mg-0.1Sr alloy prepared in this embodiment is shown in Table 1.

[0044] Table 1

[0045] element Mn Mg Sr Zn and unavoidable impurities Mass percentage (wt%) 0.51 0.10 0.11 margin

[0046] The microstructures of the forged bar and the Zn-0.5Mn-0.1Mg-0.1Sr alloy obtained in Example 1 were tested and characterized using backscattered electron diffraction (EBSD) combined with scanning electron microscopy. The results were analyzed using AZtecCrystal and Channel 5 software. Figures 1-6 As shown, comparison Figure 1 and Figure 2 Analysis shows that annealing has no effect on the grain size, phase morphology, and distribution of the alloy. The average grain size is 1 μm, with fine grains and a uniformly distributed second phase (MnZn). 13MgZn2 and SrZn 13 This gives the alloy high mechanical properties; in comparison Figure 3 and Figure 4 Analysis shows that the proportion of high KAM values ​​decreased from 12.6% to 7.3% after annealing, indicating a lower degree of local lattice distortion and a smaller strain concentration region; from Figure 5 As can be seen, subgrains form within the large grains in the forged state, while no subgrains were observed in the annealed state (see...). Figure 6 Furthermore, the recrystallization rate after annealing also increased by 5.5%, indicating that the microstructure of the annealed alloy is more stable.

[0047] Example 2

[0048] This embodiment includes the following steps:

[0049] Step 1: Prepare the ingredients according to the formula Zn-0.23Mn-0.05Mg-0.05Sr. Add zinc granules with a purity of not less than 99.99% to a crucible and heat it to 650℃. After the zinc granules are completely melted, press in manganese flakes with a purity of not less than 99.99% and strontium blocks with a purity of not less than 99.95%. At the same time, argon gas is introduced for protection and the temperature is maintained for 40 minutes, during which time the mixture is stirred 5 times. Then, press in magnesium blocks with a purity of not less than 99.99% and maintain the temperature for 18 minutes, then stir. After removing slag and filtering, the mixture is poured into a graphite mold and cooled to room temperature to obtain an alloy ingot.

[0050] Step 2: The alloy ingot obtained in Step 1 is heated to 345°C in a vacuum environment at a heating rate of 5°C / min and held for 12.5 hours. Then it is cooled in the furnace to less than 50°C and air-cooled to obtain a heat-treated ingot.

[0051] Step 3: First, the surface of the heat-treated ingot obtained in Step 2 is machined to remove the riser and oxide. Then, it is heated to 205℃ and held for 40 minutes. Then, it is extruded at an extrusion cylinder temperature of 200℃, an extrusion ratio of 16:1, and an extrusion speed of 28mm / s to obtain an extruded bar with a diameter of 12.5mm.

[0052] Step 4: The extruded bar obtained in Step 3 is subjected to multi-pass rotary forging at room temperature, with a deformation amount of 10.6% to 18.3% per pass and a total deformation amount of 58%, to obtain a rotary forged bar.

[0053] Step 5: Under vacuum conditions, heat the forged bar obtained in Step 4 to 205°C in a furnace and hold for 15 minutes. Then, cool it in the furnace for 30 minutes before removing it from the furnace to obtain the Zn-0.23Mn-0.05Mg-0.05Sr alloy.

[0054] The chemical composition of the Zn-0.23Mn-0.05Mg-0.05Sr alloy prepared in this embodiment is shown in Table 2.

[0055] Table 2

[0056] element Mn Mg Sr Zn and unavoidable impurities Mass percentage (wt%) 0.23 0.04 0.06 margin

[0057] Example 3

[0058] This embodiment includes the following steps:

[0059] Step 1: Prepare the ingredients according to the formula Zn-0.4Mn-0.1Mg-0.02Sr. Add zinc granules with a purity of not less than 99.99% to a crucible and heat it to 660℃. After the zinc granules have completely melted, press in manganese flakes with a purity of not less than 99.99% and strontium blocks with a purity of not less than 99.95%. At the same time, argon gas is introduced for protection and the temperature is maintained for 50 minutes, during which time the mixture is stirred 3 times. Then, press in magnesium blocks with a purity of not less than 99.99% and maintain the temperature for 20 minutes, then stir. After removing slag and filtering, the mixture is poured into a graphite mold and cooled to room temperature to obtain an alloy ingot.

[0060] Step 2: The alloy ingot obtained in Step 1 is heated to 355°C in a vacuum environment at a heating rate of 12°C / min and held for 11.5 hours. Then it is cooled in the furnace to less than 50°C and air-cooled to obtain a heat-treated ingot.

[0061] Step 3: First, the surface of the heat-treated ingot obtained in Step 2 is machined to remove the riser and oxide. Then, it is heated to 195℃ and held for 50 minutes. Then, it is extruded at an extrusion cylinder temperature of 190℃, an extrusion ratio of 16:1, and an extrusion speed of 22mm / s to obtain an extruded bar with a diameter of 12.5mm.

[0062] Step 4: The extruded bar obtained in Step 3 is subjected to multi-pass rotary forging at room temperature, with a deformation amount of 10.6% to 18.3% per pass and a total deformation amount of 58%, to obtain a rotary forged bar.

[0063] Step 5: Under vacuum conditions, heat the forged bar obtained in Step 4 to 195°C in a furnace and hold for 25 minutes. Then, cool it in the furnace for 35 minutes before removing it from the furnace to obtain the Zn-0.4Mn-0.1Mg-0.02Sr alloy.

[0064] The chemical composition of the Zn-0.4Mn-0.1Mg-0.02Sr alloy prepared in this embodiment is shown in Table 3.

[0065] Table 3

[0066] element Mn Mg Sr Zn and unavoidable impurities Mass percentage (wt%) 0.42 0.10 0.02 margin

[0067] Comparative Example 1

[0068] This comparative example includes the following steps:

[0069] Step 1: Prepare the Zn-0.5Mn mixture by loading zinc granules with a purity of not less than 99.99% into a crucible and heating it to 680℃. After the zinc granules have completely melted, press in manganese sheets with a purity of not less than 99.99% while simultaneously introducing argon gas for protection and holding the temperature for 60 minutes. Stir the mixture 4 times during this period. After removing slag and filtering, pour the mixture into a graphite mold and cool it to room temperature to obtain an alloy ingot.

[0070] Step 2: Heat the alloy ingot obtained in Step 1 to 350°C in a vacuum environment at a heating rate of 10°C / min, hold for 12 hours, then cool with the furnace to less than 50°C and air cool to obtain a heat-treated ingot.

[0071] Step 3: First, the surface of the heat-treated ingot obtained in Step 2 is machined to remove the riser and oxide scale. Then, it is heated to 200℃ and held for 60 minutes. Then, it is extruded at an extrusion cylinder temperature of 190℃~200℃, an extrusion ratio of 16:1, and an extrusion speed of 25mm / s to obtain an extruded bar with a diameter of 12.5mm.

[0072] Step 4: The extruded bar obtained in Step 3 is subjected to multi-pass rotary forging at room temperature, with a deformation amount of 10.6% to 18.3% per pass and a total deformation amount of 58%, to obtain a rotary forged bar.

[0073] Step 5: Under vacuum conditions, heat the forged bar obtained in Step 4 to 200°C in a furnace and hold for 20 minutes. Then, cool it in the furnace for 40 minutes before removing it from the furnace to obtain the Zn-0.5Mn alloy.

[0074] The chemical composition of the Zn-0.5Mn alloy prepared in this comparative example is shown in Table 4.

[0075] Table 4

[0076] element Mn Zn and unavoidable impurities Mass percentage (wt%) 0.46 margin

[0077] Figure 7 The stress-strain curves are shown for the forged bar and Zn-0.5Mn-0.1Mg-0.1Sr alloy prepared in Example 1 and the Zn-0.5Mn alloy prepared in Comparative Example 1. Figure 7 Example 1, annealed state, represents a Zn-0.5Mn-0.1Mg-0.1Sr alloy; Example 1, forged state, represents a forged bar. Figure 7As can be seen, after stabilization annealing, the strength of the Zn-0.5Mn-0.1Mg-0.1Sr alloy in Example 1 is reduced to a certain extent compared with the forged bar, but the elongation is almost unchanged. The strength of the Zn-0.5Mn-0.1Mg-0.1Sr alloy in Example 1 is significantly higher than that in Comparative Example 1, but the elongation is only about half that of the Comparative Example, achieving a balance between high strength and high plasticity.

[0078] Comparative Example 2

[0079] This comparative example includes the following steps:

[0080] Step 1: Mix pure zinc, Zn-Cu master alloy and pure manganese to obtain raw material mixture; wherein, the weight percentage of Cu in Zn-Cu master alloy is 5%, and the remainder is Zn;

[0081] Step 2: Melt the raw material mixture at 650℃ to obtain an alloy melt;

[0082] Step 3: Homogenize the alloy melt at 360℃ for 10 hours, and then quench and cool it to obtain the pretreated alloy body;

[0083] Step 4: After holding the pretreated alloy body at 200℃ for 30 minutes, remove it and lubricate the pretreated alloy body and extrusion die with molybdenum disulfide grease. Set the hot extrusion temperature to 200℃, the hot extrusion ratio to 25:1, and the hot extrusion rate to 0.5mm / s and perform one hot extrusion to obtain a bar with a diameter of 8mm. Cool it with water to ambient temperature and maintain its extruded structure to obtain the alloy body.

[0084] Step 5: Heat-treat the alloy body obtained in Step 4 at 330℃ for 60 minutes, cool and then anneal to obtain Zn-2.3Cu-0.8Mn alloy.

[0085] Comparative Example 3

[0086] This comparative example includes the following steps:

[0087] Step 1: Weigh out 392.8 g of Zn powder (99.99 wt.%), 0.8 g of Mn powder (99.9 wt.%), and 6.4 g of Sr (99 wt.%) in a mass ratio of 98.2:0.2:1.6. Since Sr reacts with carbon at high temperatures, first place the zinc pieces at the bottom of the graphite crucible and cover it. Then, place the zinc pieces around the crucible wall, creating a space in the center. Next, place the Mn powder and Sr blocks inside. After adding all the alloying elements to the graphite crucible, place it on an induction furnace and cover it with a quartz tube to ensure a tight seal. After sealing, turn on the argon gas switch and introduce protective gas. After waiting for 1 minute to ensure that the air in the quartz tube is expelled, turn on the electromagnetic induction furnace and slowly adjust the current. When the current is adjusted to about 800A, the raw material melts. After holding at the temperature for 5 minutes, turn off the power. After the cast alloy is solution treated at 300°C for 2 hours, the vertical extrusion die with an extrusion ratio of 4:1 is heated to 350°C through a resistance rod. After the temperature stabilizes, the cylindrical Zn-Mn-Sr rod is placed into the vertical extrusion die. After holding at the temperature for 10 minutes, the rod is extruded at a speed of 1mm / s and cooled in water to complete the first vertical extrusion.Next, the vertical extrusion die with an extrusion ratio of 25:9 is heated to 280℃ using a resistance rod. After the temperature stabilizes, the cylindrical Zn-Mn-Sr rod that has completed the first vertical extrusion is placed into the die. After holding at this temperature for 10 minutes, the rod is extruded at a speed of 1 mm / s and then cooled in water. The vertical extrusion process is now complete. The vertically extruded cylindrical Zn-Mn-Sr rod is then placed into a 90° angled, equal-channel extrusion die heated to 280℃ using a resistance rod. After holding at this temperature for 10 minutes, the rod is extruded at a speed of 1 mm / min and then quickly cooled in water. This completes the first Ecap extrusion. Finally, the cylindrical Zn-Mn-Sr rod that has completed the first extrusion is rotated 90° clockwise and placed into a 90° angled, equal-channel extrusion die heated to 280℃ using a resistance rod. After holding at this temperature for 10 minutes, the rod is extruded at a speed of 1 mm / min and then quickly cooled in water. This completes the second Ecap extrusion. The first Ecap extrusion: After two passes, the cylindrical Zn-Mn-Sr bar is rotated 90° clockwise and placed into a 90° angled extrusion die with equal channels, heated to 280°C by a resistance rod. After holding at this temperature for 10 minutes, the bar is extruded at a speed of 1 mm / min and then quickly immersed in water to cool, completing the third Ecap extrusion. The second Ecap extrusion: After three passes, the cylindrical Zn-Mn-Sr bar is rotated 90° clockwise and placed into a 90° angled extrusion die with equal channels, heated to 280°C by a resistance rod. After holding at this temperature for 10 minutes, the bar is extruded at a speed of 1 mm / min and then quickly immersed in water to cool, completing the fourth Ecap extrusion. The holding furnace is heated to 200°C, and after removing surface impurities, the alloy that has undergone the Ecap processing is placed in the furnace and held for 8 hours for aging treatment to further enhance the alloy's properties. At this point, the Zn-0.2Mn-1.6Sr alloy is prepared.

[0088] Comparative Example 4

[0089] The difference between this comparative example and Comparative Example 3 is that the Zn-0.7Mn-1.3Sr alloy was prepared.

[0090] Comparative Example 5

[0091] The difference between this comparative example and Comparative Example 3 is that the Zn-0.5Mn-1.5Sr alloy was prepared.

[0092] Comparative Example 6

[0093] The difference between this comparative example and Comparative Example 3 is that it prepares a Zn-1.7Mn-1.3Sr alloy.

[0094] Comparative Example 7

[0095] The difference between this comparative example and Comparative Example 3 is that the Zn-0.1Mn-2.9Sr alloy was prepared.

[0096] The alloys prepared in Examples 1, 2, 3, Comparative Examples 1, 2, 3, 4, 5, 6, and 7 of this invention, as well as the alloys in the intermediate state, were subjected to room temperature tensile mechanical property analysis. The results are shown in Table 5.

[0097] Table 5

[0098]

[0099]

[0100] As can be seen from Table 5, after heat treatment, the mechanical properties of the alloys in Examples 1, 2, 3, Comparative Example 1, and Comparative Example 2 all changed to a certain extent. The strength of the alloys in Examples 1, 2, and 3 decreased to a certain extent, while the elongation after fracture and reduction of area remained almost unchanged. Both the strength and plasticity met the requirements for medical use. Compared with Comparative Example 1, the strength of the alloy in Example 1 increased significantly after the addition of 0.1% Mg and 0.1% Sr, with the tensile strength increasing by 116% and the yield strength increasing by 177%. The plasticity decreased significantly, with the elongation after fracture decreasing by 58% and the reduction of area decreasing by 37%. It still significantly exceeded the requirements for medical use, which also indirectly confirms the role of adding Mg and Sr in this application. The strength and plasticity of the alloys prepared in Examples 1 to 3 are much higher than those in Comparative Example 3, Comparative Example 4, Comparative Example 5, Comparative Example 6, and Comparative Example 7, and the content of alloying elements is also significantly lower.

[0101] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A high-strength, high-ductility, low-alloying-element-content Zn-Mn-Mg-Sr alloy, characterized in that, The chemical composition of this Zn-Mn-Mg-Sr alloy, by mass percentage, is: Mn 0.23%~0.5%, Mg 0.05%~0.1%, Sr 0.02%~0.1%, with the balance being Zn; and the total content of Mn, Mg and Sr is 0.3%~0.7%. The preparation method of the Zn-Mn-Mg-Sr alloy includes the following steps: Step 1: Melt zinc granules, manganese flakes, magnesium blocks, and strontium blocks to obtain alloy ingots; Step 2: The alloy ingot obtained in Step 1 is subjected to homogenization heat treatment to obtain a heat-treated ingot. Step 3: Extrude the heat-treated ingot obtained in Step 2 to obtain extruded bars; the extrusion process is as follows: first, the surface of the zinc alloy ingot is machined to remove the riser and oxide scale, then heated to 195℃~205℃ and held for 40min~60min, and then extruded at an extrusion cylinder temperature of 190℃~200℃, an extrusion ratio of 16:1, and an extrusion speed of 22mm / s~28mm / s. Step 4: Perform multi-pass rotary forging on the extruded bar obtained in Step 3 to obtain a rotary forged bar; the multi-pass rotary forging is carried out at room temperature, and the deformation amount of each pass is 10.6%~18.3%, with a total deformation amount exceeding 50%; Step 5: Stabilize and anneal the forged bar obtained in Step 4 to obtain a Zn-Mn-Mg-Sr alloy. The stabilization and annealing process is as follows: under vacuum conditions, heat the furnace to 195℃~205℃, hold for 15min~25min, then cool for 30min~40min before removing from the furnace. The mechanical properties of the Zn-Mn-Mg-Sr alloy are: tensile strength greater than 300MPa, yield strength greater than 200MPa, elongation after fracture greater than 30%, and reduction of area greater than 60%.

2. The high-strength, high-ductility, low-alloy element content Zn-Mn-Mg-Sr alloy according to claim 1, characterized in that, The smelting process described in step one is as follows: zinc granules are placed in a crucible and heated to 650℃~680℃. After the zinc granules are completely melted, manganese sheets and strontium blocks are pressed in, and argon gas is introduced for protection. The temperature is maintained for 40min~60min, and the mixture is stirred 3~5 times during this period. Then, magnesium blocks are pressed in and the temperature is maintained for 15min~20min, followed by stirring. After slag removal and filtration, the mixture is poured into a graphite mold and cooled to room temperature.

3. The high-strength, high-ductility, low-alloy element content Zn-Mn-Mg-Sr alloy according to claim 1, characterized in that, The zinc granules mentioned in step one have a purity of not less than 99.99%, the manganese sheets have a purity of not less than 99.99%, the magnesium blocks have a purity of not less than 99.99%, and the strontium blocks have a purity of not less than 99.95%.

4. The high-strength, high-ductility, low-alloy element content Zn-Mn-Mg-Sr alloy according to claim 1, characterized in that, The homogenization heat treatment process described in step two is as follows: heating to 345℃~355℃ in a vacuum environment at a heating rate of 5℃ / min~12℃ / min, holding at that temperature for 11.5h~12.5h, and then cooling with the furnace to less than 50℃ before air cooling.

5. A high-strength, high-ductility, low-alloy element content Zn-Mn-Mg-Sr alloy according to claim 1, characterized in that, The Zn-Mn-Mg-Sr alloy described in step five is used in the field of implantable and interventional medical devices.

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