An ultra-low elastic modulus biomedical zirconium alloy and a preparation method thereof

Abstract

The application discloses an ultra-low elastic modulus biomedical zirconium alloy and a preparation method thereof. The alloy contains three alloying elements, and the mass percentage of the three alloying elements is as follows: Zr 71-80wt%, Nb 20wt%, Ta 1-9wt%, and the rest is inevitable impurities. In the preparation, the content of Ta is controlled, and three-stage solid solution-ageing-quenching heat treatment is combined to effectively stabilize the beta-Zr phase, and the synergistic optimization of the elastic modulus and the strength of the alloy is realized. With the increase of the content of Ta, the tensile strength of the alloy increases first and then decreases, and the elastic modulus of the alloy decreases first and then increases. When the content of Ta is optimal, the elastic modulus of the alloy is as low as 15.2 GPa, and the peak value of the tensile strength is 861 MPa. The "stress shielding effect" is significantly inhibited, and the mechanical matching with the bone tissue and the long-term stability of the implant are greatly improved.

Description

Technical Field

[0001] This invention relates to the field of zirconium alloys, particularly to their applications in biomedicine, and specifically to a method for preparing an ultra-low elastic modulus biomedical zirconium alloy. Background Technology

[0002] With the continued growth in demand for biomedical implants, zirconium alloys with excellent biocompatibility have become a research hotspot. While the currently mainstream Zr-2.5Nb alloy meets basic clinical requirements, its elastic modulus (70-100 GPa) is significantly higher than that of human bone (7-30 GPa). Long-term implantation can easily lead to stress shielding effects, resulting in bone resorption and implant failure. Therefore, developing novel zirconium alloys with both ultra-low elastic modulus (<60 GPa) and high strength (>800 MPa) has become an urgent industry need.

[0003] To synergistically reduce the elastic modulus while maintaining high strength, researchers generally modify zirconium-based alloys by controlling alloying elements (such as β-stabilizing elements Nb, Ta, Mo, Sn, etc.), optimizing microstructure, and employing heat treatment processes. The closest existing technology is patent CN115198160A (Southern Medical University), which discloses a Zr-Nb alloy for dual-motion hip joints. This technology mainly involves adding Mo (3-10wt%), Ti (7-12wt%), and Sn (10-20wt%) elements, and employing a heat treatment process of vacuum melting → solution treatment (800-900℃) → multi-stage annealing (600-750℃). Although it reduces the modulus to ≥70GPa, the elastic modulus remains too high, failing to meet the requirements of ideal bone-material mechanical matching.

[0004] Based on this, this study aims to significantly reduce the elastic modulus of zirconium alloys while ensuring they retain the necessary strength properties. To this end, the Zr-Nb-Ta alloy system was investigated in detail, and a novel three-stage heat treatment process was designed. This process aims to achieve refined control of the microstructure and synergistic optimization of performance, effectively reducing the alloy's elastic modulus and significantly improving its tensile strength. It is expected to achieve more ideal bone-material mechanical compatibility in orthopedic implants, promoting the clinical application of high-performance biomaterials. Summary of the Invention

[0005] This invention addresses the problems of high elastic modulus and insufficient mechanical compatibility in existing zirconium-based biomedical alloys by providing a method for preparing an ultra-low elastic modulus biomedical zirconium alloy. This alloy precisely introduces Ta into a Zr–20wt% Nb matrix, forming a Zr-Nb-Ta alloy system. During preparation, by controlling the Ta content and combining it with a three-stage solution-aging quenching heat treatment, the β-Zr phase is effectively stabilized, achieving synergistic optimization of the alloy's elastic modulus and strength. The alloy obtained by this invention exhibits a trend of first increasing and then decreasing tensile strength, and first decreasing and then increasing elastic modulus, with increasing Ta content. When the Ta content is optimal, the alloy's elastic modulus can reach as low as 15.2 GPa, and its peak tensile strength can reach 861 MPa, significantly suppressing the "stress shielding effect" and greatly improving its mechanical compatibility with bone tissue and the long-term stability of the implant. Furthermore, this invention features a simple and controllable preparation process, excellent biocompatibility, and suitability for the industrial application of high-end orthopedic implant materials.

[0006] The technical solution of this invention is as follows:

[0007] A biomedical zirconium alloy with ultra-low elastic modulus contains three alloying elements in the following mass percentages: Zr 71-80wt%, Nb 20wt%, Ta 1-9wt%, with the balance being unavoidable impurities.

[0008] The preparation method of the ultra-low elastic modulus biomedical zirconium alloy includes the following steps:

[0009] Step 1: Vacuum Arc Melting

[0010] (1) After cleaning the pure Zr, pure Nb and pure Ta raw materials, they are mixed according to the designed mass percentage ratio;

[0011] (2) Place the prepared raw materials in the water-cooled copper crucible of the non-consumable vacuum arc melting furnace, close the valve, and evacuate to a high vacuum of -4.5 to -5×10-3 Pa;

[0012] (3) Fill the electric arc furnace cavity with high-purity argon gas of -0.4 to -0.6 MPa, and then perform arc ignition and melting. The melting current is 150 to 200 A / S. Repeat the melting process by flipping the furnace over 5 to 6 times, each melting process lasting 5 to 7 minutes, to obtain the ingot alloy.

[0013] Step 2: Three-stage quenching and solution aging heat treatment process

[0014] (1) Place the smelted ingot alloy into a vacuum tube furnace, purge with high-purity argon gas for 3-4 times, and then heat to 1050-1100℃ in an argon atmosphere, hold for 2-5 hours, and quench.

[0015] (2) Reheat to 900-1000℃, hold for 0.5-3 hours, and quench;

[0016] (3) Finally, heat to 300-400℃, hold for 0.5-3 hours, quench, and obtain ultra-low modulus biomedical zirconium alloy.

[0017] The preparation method of the ultra-low elastic modulus biomedical zirconium alloy mentioned above uses industrial-grade sponge zirconium as pure Zr, 99.9% pure Nb particles, and 99.9% pure Ta particles.

[0018] The preparation method of the ultra-low elastic modulus biomedical zirconium alloy uses high-purity argon gas with a purity of 99.999%.

[0019] The essential features of this invention are:

[0020] 1. Novel ingredient design (breakthrough in precise component range):

[0021] In a Zr–20wt%Nb matrix, 1–9wt%Ta is precisely introduced. By synergistically regulating the stability window of the β-Zr phase with Ta / Nb, the precipitation tendency of the high-modulus brittle ω phase and α″ phase is effectively suppressed at the atomic scale (especially avoiding the difficulties in subsequent processing or modulus recovery caused by the overstability of the β phase under high Ta content), laying an irreplaceable compositional foundation for obtaining ultra-low elastic modulus (<20GPa).

[0022] 2. Novel heat treatment process (unique three-stage quenching sequence and target phase control):

[0023] The pioneering "three-stage quenching, solution treatment, and aging" process is innovative in that its core innovation lies in the specific combination of temperature windows and quenching steps, aiming to precisely control the β-phase decomposition path and the type / size of precipitated phases.

[0024] (1) First-level high-temperature homogenization quenching (1050–1100℃ / 5h → quenching): The key is the ultra-high temperature, which completely eliminates the segregation in the casting state and obtains a single β phase with highly uniform composition.

[0025] (2) Secondary medium-temperature solution quenching (900–1000℃ / 2h → quenching): The key is to keep the temperature in the medium temperature range and adjust the supersaturation of the β phase. After quenching, a metastable β phase matrix with a specific supersaturation is obtained.

[0026] (3) Three-stage low-temperature aging quenching (300–400℃ / 2h → quenching): Short-term holding at extremely low temperatures precisely induces the precipitation of high-density, nanoscale ω phase (rather than the α phase or coarse ω phase commonly found in traditional Zr alloys). The quenching operation is crucial in this step, as its purpose is to immediately freeze the microstructure, preventing the ω phase from growing or transforming into the α phase during cooling, thereby ensuring the acquisition of a diffusely distributed nanoscale ω strengthening phase, significantly improving strength without significantly increasing the elastic modulus, and eliminating internal stress.

[0027] The beneficial effects of this invention are as follows:

[0028] (1) Ultra-low elastic modulus

[0029] By precisely adding Ta (1–9 wt%) and employing a three-stage solution-aging quenching process, the average elastic modulus of the alloy can be reduced to 15.2 GPa (nanoindentation test). Figure 4 As shown in the figure, it closely matches human bone (7–30 GPa), effectively reducing the stress shielding effect after implantation. Compared to conventional Zr-2.5Nb heat-treated alloys (elastic modulus > 70 GPa), this invention reduces stress by more than 78%.

[0030] (2) High tensile strength

[0031] After three-stage quenching heat treatment, the alloy's ultimate tensile strength (UTS) can reach up to 864 MPa (tensile curve shown). Figure 3 This is approximately 54% higher than that of conventional Zr-2.5Nb (≈560MPa). Simultaneously, the yield strength reaches 864MPa, and the elongation after fracture is 10.95%, sufficient to meet the mechanical requirements of high-load orthopedic implants.

[0032] (3) The process is simple and controllable and easy to industrialize.

[0033] The equipment used includes only conventional vacuum arc melting furnaces and vacuum tube furnaces. Parameters (temperature, holding time, cooling rate) can be precisely controlled by PLC, with high repeatability, making it suitable for large-scale production.

[0034] (4) Excellent biocompatibility

[0035] The selected alloying elements Zr / Nb / Ta are all medical-grade materials, meeting the safety requirements for orthopedic implantation. Attached Figure Description

[0036] Figure 1 This is a flow chart of the heat treatment process of the present invention;

[0037] Figure 2 These are scanning morphology images of zirconium alloys from Examples 1-7 and Comparative Example 1;

[0038] Figure 3The tensile stress-strain curves of zirconium alloys in Examples 1-7 and Comparative Example 1 are shown.

[0039] Figure 4 The dynamic ultramicro force-displacement curves of zirconium alloys in Examples 1-7 and Comparative Example 1 are shown. Detailed Implementation

[0040] The embodiments of the present invention will be described in further detail below to make the technical process, purpose and advantages of the invention clearer.

[0041] This invention provides an ultra-low elastic modulus high strength and toughness zirconium alloy and its preparation method. The atomic percentages of the three elements by mass percentage are: Zr 71-80wt%, Nb 20wt%, Ta 1-9wt%, with the balance being unavoidable impurities.

[0042] The Nb and Ta elements introduced into the zirconium alloy of this invention are both non-toxic to the human body and are β-stable elements, with the aim of obtaining more β-Zr microstructure. β-Zr has a cubic structure and more slip systems than α-Zr (hexagonal close-packed), thereby reducing the elastic modulus. Furthermore, a three-stage quenching and solution aging process is employed. The first stage of quenching eliminates melting defects, homogenizes the composition, and yields a saturated β phase; the second stage of quenching is a solution treatment to improve the solution strength and yields a supersaturated β phase; the third stage of quenching and aging aims to precipitate the nano-ω phase, improve strength, and prevent the growth of the nano-phase. The final product is a low-modulus, high-strength biomedical zirconium alloy.

[0043] This invention also provides a low-density, high-strength, and high-toughness zirconium alloy and its preparation method, comprising the following steps:

[0044] (1) The alloy raw materials are melted by non-consumable vacuum arc to obtain ingot alloys;

[0045] (2) The ingot alloy is subjected to a three-stage quenching solution aging treatment to obtain a pure β-phase high-strength zirconium alloy with low elastic modulus.

[0046] This invention obtains ingot alloys by non-consumable vacuum arc melting of alloy raw materials. In this invention, the type of alloy raw material is not specifically limited; alloy raw materials well-known to those skilled in the art are used, with the aim of obtaining zirconium alloys with the target composition. The alloy raw materials used in this invention are industrial-grade sponge zirconium, pure Ta particles, and pure Nb particles. This invention has no special requirements on the particle size of the raw materials.

[0047] In this invention, the alloy raw materials are cleaned and dried before being smelted. The alloy smelting is preferably non-consumable vacuum arc melting (NCA), using a WK series vacuum arc furnace. The current for NCA is preferably 130–210 A / s, more preferably 170–200 A / s. NCA is preferably carried out in an argon-protected gas atmosphere, with a pressure preferably -0.04 to -0.06 MPa. The argon flow rate is sufficient to meet the ionization gas requirements for arc melting. When using NCA, this invention preferably first evacuates the furnace to a vacuum level of -5 × 10⁻⁵ MPa. -3 Below Pa, argon gas is introduced. The non-consumable vacuum arc melting of the alloy in this invention is preferably repeated 5 to 8 times, more preferably 7 to 8 times. This invention preferably involves repeated flipping during melting, the melting process being carried out in a water-cooled copper crucible within a non-consumable vacuum melting furnace. This invention preferably allows the ingot alloy to cool after each non-consumable vacuum melting operation, then flips the cooled ingot alloy and continues with the next non-consumable vacuum melting operation. In this invention, each independent non-consumable vacuum melting process is preferably 4 to 7 minutes, more preferably 5 to 6 minutes. The preferred repeated flipping during non-consumable vacuum melting ensures a more uniform composition of the ingot alloy. After obtaining the ingot alloy, this invention performs homogenization annealing to obtain a zirconium alloy ingot with uniform microstructure and composition.

[0048] In this invention, a three-stage quenching, solution treatment, and aging process is preferably performed using a vacuum tube furnace. The annealing process preferably uses argon as the protective gas, and the annealing temperatures are 1050-1100℃, preferably 1050℃; 900-1000℃, preferably 950℃; and 300-400℃, preferably 350℃. The holding times are 5, 2, and 2 hours respectively.

[0049] To further illustrate the present invention, the following detailed description of the low-density, high-strength, and high-toughness zirconium alloy and its preparation method provided by the present invention is provided in conjunction with embodiments, but these should not be construed as limiting the scope of protection of the present invention.

[0050] Comparative Example 1

[0051] (1) The Zr-20Nb alloy was prepared according to the mass percentage, taking 80.0135g of industrial-grade sponge zirconium (purity 99.5%) and 20.0025g of Nb particles with a purity of 99.9%. They were then ultrasonically cleaned in anhydrous ethanol for 15 min.

[0052] (2) Place the prepared raw materials in a water-cooled copper crucible in a non-consumable vacuum melting furnace, and evacuate to a high vacuum of -5×10⁻⁵. - 3Below Pa; argon gas with a purity of 99.999% is introduced into the non-consumable vacuum arc melting furnace until the pressure gauge reading is between -0.04 MPa and -0.06 MPa. Melting is then performed. After arc ignition, the 20g pure zirconium ingot used for additional arc ignition is melted for 5 minutes to consume the oxygen and nitrogen in the furnace. The target alloy is then melted, with each melting lasting 5 minutes. The ingot is repeatedly turned over and melted 8 times to obtain the ingot alloy. The melting current is 160–200 A / s.

[0053] (3) The ingot alloy was placed in a vacuum tube furnace for heat treatment. Under an argon atmosphere with a purity of 99.999%, it was first heated to 1050℃, held for five hours, and then quenched; then heated to 950℃, held for two hours, and then quenched; finally heated to 350℃, held for two hours, and then quenched. The heat-treated zirconium alloy ingot was obtained.

[0054] (4) The ingot is processed by an electrical discharge wire cutting machine to cut out the test specimens of the required size for subsequent testing.

[0055] Example 1

[0056] (1) The Zr-20Nb-1Ta alloy was prepared according to the following mass percentages: 78.9963g of industrial-grade sponge zirconium (purity 99.5%), 20.0330g of Nb particles (purity 99.9%), and 1.0006g of Ta particles (purity 99.9%). Each particle was then ultrasonically cleaned in anhydrous ethanol for 15 minutes.

[0057] (2) Place the prepared raw materials in a water-cooled copper crucible in a non-consumable vacuum melting furnace, and evacuate to a high vacuum of -5×10⁻⁵. - 3 Below Pa; argon gas with a purity of 99.999% is introduced into the non-consumable vacuum arc melting furnace until the pressure gauge reading is between -0.04 MPa and -0.06 MPa. Melting is then performed. After arc ignition, the 20g sponge zirconium ingot used for additional arc ignition is melted for 5 minutes to consume the oxygen and nitrogen in the furnace. The target alloy is then melted, with each melting lasting 5 minutes. The ingot is repeatedly turned over and melted 8 times to obtain the ingot alloy. The melting current is 160–200 A / s.

[0058] (3) The ingot alloy was placed in a vacuum tube furnace for heat treatment. Under an argon atmosphere with a purity of 99.999%, it was first heated to 1050℃, held for five hours, and then quenched; then heated to 950℃, held for two hours, and then quenched; finally heated to 350℃, held for two hours, and then quenched. The heat-treated zirconium alloy ingot was obtained.

[0059] (4) The ingot is processed by an electrical discharge wire cutting machine to cut out the test specimens of the required size for subsequent testing.

[0060] Example 2

[0061] (1) The Zr-20Nb-2Ta alloy was prepared according to the following mass percentages: 78.0056g of industrial-grade sponge zirconium, 19.9963g of Nb particles with a purity of 99.9%, and 1.9983g of Ta particles with a purity of 99.9%. Each particle was then ultrasonically cleaned in anhydrous ethanol for 15 minutes.

[0062] (2) Place the prepared raw materials in a water-cooled copper crucible in a non-consumable vacuum arc melting furnace, and evacuate to a high vacuum below -5×10-3 Pa; fill the furnace cavity with 99.999% pure argon gas until the pressure gauge reading is between -0.04MPa and -0.06MPa, and then proceed with the melting operation. After ignition, first melt the 20g pure zirconium ingot used for ignition for 5 minutes to consume the oxygen and nitrogen in the furnace, and then melt the target alloy. Melt for 5 minutes each time, and repeatedly turn the ingot over to melt it 8 times to obtain the ingot alloy. The melting current is 160-200A / S.

[0063] (3) The ingot alloy was placed in a vacuum tube furnace for heat treatment. Under an argon atmosphere with a purity of 99.999%, it was first heated to 1050℃, held for five hours, and then quenched; then heated to 950℃, held for two hours, and then quenched; finally heated to 350℃, held for two hours, and then quenched. The heat-treated zirconium alloy ingot was obtained.

[0064] (4) The ingot is processed by an electrical discharge wire cutting machine to cut out the test specimens of the required size for subsequent testing.

[0065] Example 3

[0066] (1) The Zr-20Nb-3Ta alloy was prepared according to the following mass percentages: 77.0050g of industrial-grade sponge zirconium, 19.9962g of Nb particles with a purity of 99.9%, and 3.0101g of Ta particles with a purity of 99.9%. Each particle was then ultrasonically cleaned in anhydrous ethanol for 15 minutes.

[0067] (2) Place the prepared raw materials in a water-cooled copper crucible in a non-consumable vacuum arc melting furnace, and evacuate to a high vacuum below -5×10-3 Pa; fill the furnace cavity with 99.999% pure argon gas until the pressure gauge reading is between -0.04MPa and -0.06MPa, and then proceed with the melting operation. After ignition, first melt the 20g pure zirconium ingot used for ignition for 5 minutes to consume the oxygen and nitrogen in the furnace, and then melt the target alloy. Melt for 5 minutes each time, and repeatedly turn the ingot over to melt it 8 times to obtain the ingot alloy. The melting current is 160-200A / S.

[0068] (3) The ingot alloy was placed in a vacuum tube furnace for heat treatment. Under an argon atmosphere with a purity of 99.999%, it was first heated to 1050℃, held for five hours, and then quenched; then heated to 950℃, held for two hours, and then quenched; finally heated to 350℃, held for two hours, and then quenched. The heat-treated zirconium alloy ingot was obtained.

[0069] (4) The ingot is processed by an electrical discharge wire cutting machine to cut out the test specimens of the required size for subsequent testing.

[0070] Example 4

[0071] (1) The Zr-20Nb-4Ta alloy was prepared according to the following mass percentages: 76.0000g of industrial-grade sponge zirconium, 20.0389g of Nb particles with a purity of 99.9%, and 4.0032g of Ta particles with a purity of 99.9%. Each particle was then ultrasonically cleaned in anhydrous ethanol for 15 minutes.

[0072] (2) Place the prepared raw materials in a water-cooled copper crucible in a non-consumable vacuum arc melting furnace, and evacuate to a high vacuum below -5×10-3 Pa; fill the furnace cavity with 99.999% pure argon gas until the pressure gauge reading is between -0.04MPa and -0.06MPa, and then proceed with the melting operation. After ignition, first melt the 20g pure zirconium ingot used for ignition for 5 minutes to consume the oxygen and nitrogen in the furnace, and then melt the target alloy. Melt for 5 minutes each time, and repeatedly turn the ingot over to melt it 8 times to obtain the ingot alloy. The melting current is 160-200A / S.

[0073] (3) The ingot alloy was placed in a vacuum tube furnace for heat treatment. Under an argon atmosphere with a purity of 99.999%, it was first heated to 1050℃, held for five hours, and then quenched; then heated to 950℃, held for two hours, and then quenched; finally heated to 350℃, held for two hours, and then quenched. The heat-treated zirconium alloy ingot was obtained.

[0074] (4) The ingot is processed by an electrical discharge wire cutting machine to cut out the test specimens of the required size for subsequent testing.

[0075] Example 5

[0076] (1) The Zr-20Nb-5Ta alloy was prepared according to the following mass percentages: 75.0283g of industrial-grade sponge zirconium, 20.1302g of Nb particles with a purity of 99.9%, and 5.0061g of Ta particles with a purity of 99.9%. Each particle was then ultrasonically cleaned in anhydrous ethanol for 15 minutes.

[0077] (2) Place the prepared raw materials in a water-cooled copper crucible in a non-consumable vacuum arc melting furnace, and evacuate to a high vacuum below -5×10-3 Pa; fill the furnace cavity with 99.999% pure argon gas until the pressure gauge reading is between -0.04MPa and -0.06MPa, and then proceed with the melting operation. After ignition, first melt the 20g pure zirconium ingot used for ignition for 5 minutes to consume the oxygen and nitrogen in the furnace, and then melt the target alloy. Melt for 5 minutes each time, and repeatedly turn the ingot over to melt it 8 times to obtain the ingot alloy. The melting current is 160-200A / S.

[0078] (3) The ingot alloy was placed in a vacuum tube furnace for heat treatment. Under an argon atmosphere with a purity of 99.999%, it was first heated to 1050℃, held for five hours, and then quenched; then heated to 950℃, held for two hours, and then quenched; finally heated to 350℃, held for two hours, and then quenched. The heat-treated zirconium alloy ingot was obtained.

[0079] (4) The ingot is processed by an electrical discharge wire cutting machine to cut out the test specimens of the required size for subsequent testing.

[0080] Example 6

[0081] (1) The Zr-20Nb-7Ta alloy was prepared according to the following mass percentages: 72.9961g of industrial-grade sponge zirconium, 20.0108g of Nb particles with a purity of 99.9%, and 7.0222g of Ta particles with a purity of 99.9%. Each particle was then ultrasonically cleaned in anhydrous ethanol for 15 minutes.

[0082] (2) Place the prepared raw materials in a water-cooled copper crucible in a non-consumable vacuum arc melting furnace, and evacuate to a high vacuum below -5×10-3 Pa; fill the furnace cavity with 99.999% pure argon gas until the pressure gauge reading is between -0.04MPa and -0.06MPa, and then proceed with the melting operation. After ignition, first melt the 20g pure zirconium ingot used for ignition for 5 minutes to consume the oxygen and nitrogen in the furnace, and then melt the target alloy. Melt for 5 minutes each time, and repeatedly turn the ingot over to melt it 8 times to obtain the ingot alloy. The melting current is 160-200A / S.

[0083] (3) The ingot alloy was placed in a vacuum tube furnace for heat treatment. Under an argon atmosphere with a purity of 99.999%, it was first heated to 1050℃, held for five hours, and then quenched; then heated to 950℃, held for two hours, and then quenched; finally heated to 350℃, held for two hours, and then quenched. The heat-treated zirconium alloy ingot was obtained.

[0084] (4) The ingot is processed by an electrical discharge wire cutting machine to cut out the test specimens of the required size for subsequent testing.

[0085] Example 7

[0086] (1) The Zr-20Nb-9Ta alloy was prepared according to the following mass percentages: 71.0025g of industrial-grade sponge zirconium, 19.9984g of Nb particles with a purity of 99.9%, and 9.0103g of Ta particles with a purity of 99.9%. Each particle was then ultrasonically cleaned in anhydrous ethanol for 15 minutes.

[0087] (2) Place the prepared raw materials in a water-cooled copper crucible in a non-consumable vacuum arc melting furnace, and evacuate to a high vacuum below -5×10-3 Pa; fill the furnace cavity with 99.999% pure argon gas until the pressure gauge reading is between -0.04MPa and -0.06MPa, and then proceed with the melting operation. After ignition, first melt the 20g pure zirconium ingot used for ignition for 5 minutes to consume the oxygen and nitrogen in the furnace, and then melt the target alloy. Melt for 5 minutes each time, and repeatedly turn the ingot over to melt it 8 times to obtain the ingot alloy. The melting current is 160-200A / S.

[0088] (3) The ingot alloy was placed in a vacuum tube furnace for heat treatment. Under an argon atmosphere with a purity of 99.999%, it was first heated to 1050℃, held for five hours, and then quenched; then heated to 950℃, held for two hours, and then quenched; finally heated to 350℃, held for two hours, and then quenched. The heat-treated zirconium alloy ingot was obtained.

[0089] (4) The ingot is processed by an electrical discharge wire cutting machine to cut out the test specimens of the required size for subsequent testing.

[0090] The zirconium alloy samples prepared in Examples 1-7 and Comparative Example 1 were etched using Kohler etching solution (HF:HCl:HNO3:H2O = 1:1.5:2.5:95). Scanning electron microscopy (SEM) was performed on the samples (instrument model: JSM-7100F), and the scan images are shown below. Figure 2 As shown in the figure, the morphology of the Zr-20Nb alloy changes after the addition of Ta. The microstructure in Example 2 is the most unique, exhibiting a banded structure. This structure may enhance its mechanical properties, while increasing the amount of slip during strain, thereby reducing the elastic modulus.

[0091] Tensile properties were tested on the zirconium alloy samples prepared in Examples 1-7 and Comparative Example 1 (instrument model: WDW-200). Stress-strain curves are shown below. Figure 3As shown in Table 1, the mechanical properties are as follows. In the figure, with increasing Ta content, the strength of 1Ta and 2Ta alloys is higher than that of the comparative example. The highest strength is achieved by the Zr-20Nb-2Ta alloy in Example 2, reaching 864 MPa, exceeding the comparative example by 64 MPa, and nearly 300 MPa higher than the common Zr-2.5Nb alloy, meeting the strength requirements for artificial implant alloys. With further increases in Ta content, the strength decreases. This is because the addition of a small amount of Ta provides solid solution strengthening to the zirconium alloy; however, with further increases in Ta content, the supersaturated Ta element becomes a defect in the alloy's mechanical property testing, reducing its strength.

[0092] Microhardness tests were performed on the zirconium alloy samples prepared in Examples 1-7 and Comparative Example 1 (instrument model: HMV-2T). The experimental results are shown in Table 1. The trend of hardness value variation shows a certain similarity with the strength. Among them, 2Ta has a relatively high hardness value of 355HV. Subsequently, with the increase of Ta content, the hardness value decreases to a certain extent.

[0093] Dynamic ultramicroelastic modulus testing was performed on the zirconium alloy samples prepared in Examples 1-7 and Comparative Example 1 (instrument model: DUH-211S). Their force-displacement curves are shown below. Figure 4 As shown in Table 1, the mechanical properties are as follows. It can be seen from the figure that the slope of 2Ta is significantly lower than that of other alloys, and its modulus is only 15.2 GPa. The elastic modulus of human bone is 7-30 GPa, perfectly matching the modulus of human bone, thus reducing stress shielding.

[0094] Table 1 Comparison of Mechanical Performance Parameters

[0095]

[0096] This invention is illustrated by way of examples, but does not constitute a limitation thereof. Referring to the description of this invention, other variations in the disclosed examples are readily conceived by researchers in the field of zirconium alloys, and such variations should fall within the scope defined by the claims of this invention.

[0097] Matters not covered in this invention are common knowledge.

Claims

1. A biomedical zirconium alloy with ultra-low elastic modulus, characterized in that, The alloy has the following composition by mass percentage: Zr 71-80wt%, Nb 20wt%, Ta 1-9wt%, with the balance being unavoidable impurities; The preparation method of the ultra-low elastic modulus biomedical zirconium alloy includes the following steps: Step 1: Vacuum Arc Melting (1) After cleaning the pure Zr, pure Nb and pure Ta raw materials, they are mixed according to the designed mass percentage ratio; (2) Place the prepared raw materials in the water-cooled copper crucible of the non-consumable vacuum arc melting furnace, close the valve, and evacuate to a high vacuum of -4.

5. -3 Pa ~ -5×10 -3 Pa; (3) Fill the electric arc furnace cavity with high-purity argon gas of -0.4Mpa to -0.6Mpa, and then perform arc ignition and melting. The melting current is 150 to 200A / S. Repeat the melting process by flipping the furnace over 5 to 6 times, each melting process lasting 5 to 7 minutes, to obtain the ingot alloy. Step 2: Three-stage quenching and solution aging heat treatment process (1) Place the smelted ingot alloy into a vacuum tube furnace, purge with high-purity argon gas for 3-4 times, and then heat to 1050-1100℃ in an argon atmosphere, hold for 2-5 hours, and then quench. (2) Reheat to 900-1000℃, hold for 0.5-3 hours, and quench; (3) Finally, heat to 300-400℃, hold for 0.5-3 hours, quench, and obtain ultra-low modulus biomedical zirconium alloy.

2. The ultra-low elastic modulus biomedical zirconium alloy as described in claim 1, characterized in that, The pure Zr mentioned is industrial-grade sponge zirconium, the pure Nb has a purity of 99.9%, and the pure Ta has a purity of 99.9%.

3. The ultra-low elastic modulus biomedical zirconium alloy as described in claim 1, characterized in that, The purity of high-purity argon gas is 99.999%.

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