Biomedical zirconium alloy with ultralow elastic modulus and preparation method thereof

Abstract

The invention relates to a biomedical zirconium alloy with ultralow elastic modulus and a preparation method thereof. The alloy comprises the following three alloy elements in percentage by mass: 71 to 80 weight percent of Zr, 20 weight percent of Nb, 1 to 9 weight percent of Ta and the balance of inevitable impurities. In the preparation process, by regulating and controlling the Ta content and combining three-stage solid solution-aging quenching heat treatment, the beta-Zr phase is effectively stabilized, and collaborative optimization of the elastic modulus and the strength of the alloy is achieved. According to the alloy obtained through the method, along with the increase of the Ta content, the tensile strength of the alloy is in the trend that the tensile strength is firstly increased and then decreased, and the elastic modulus is firstly decreased and then increased; when the Ta content is optimal, the lowest elasticity modulus of the alloy can reach 15.2 GPa, the tensile strength peak value can reach 861 MPa, the stress shielding effect is remarkably inhibited, and the mechanical matching property with bone tissues and the long-term stability of implants are greatly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of zirconium alloys, especially in the application of biomedical, in particular to a preparation method of an ultra-low elastic modulus biomedical zirconium alloy. BACKGROUND

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

[0003] To synergistically reduce the elastic modulus and maintain high strength, researchers generally modify zirconium-based alloys by adjusting alloying elements (such as β-stabilizing elements Nb, Ta, Mo, Sn, etc.), optimizing microstructure, and using heat treatment processes. Among them, the closest prior art is patent CN115198160A (South Medical University), which discloses a Zr-Nb alloy for a double-movement hip joint. This technology mainly adds Mo (3-10 wt%), Ti (7-12 wt%), Sn (10-20 wt%) elements, and uses a heat treatment process of vacuum melting → solid solution treatment (800-900℃) → multi-stage annealing (600-750℃). Although its modulus is reduced to ≥70 GPa, the elastic modulus is still high, which does not meet the ideal bone-material mechanical matching requirements.

[0004] Based on this, the present study aims to further significantly reduce the elastic modulus of zirconium alloys and ensure that they have the necessary strength performance. To this end, the Zr-Nb-Ta alloy system is studied, and a three-stage heat treatment process is innovatively designed. This process aims to achieve fine control of the microstructure and synergistic optimization of performance, which can not only effectively reduce the elastic modulus of the alloy, but also significantly improve its tensile strength, which is expected to achieve more ideal bone-material mechanical adaptability in orthopedic implant applications and promote the clinical application of high-performance biomaterials. SUMMARY

[0005] The present application aims at the problem of high elastic modulus and insufficient mechanical matching of the existing zirconium-based biomedical alloy, and provides a preparation method of an ultra-low elastic modulus biomedical zirconium alloy. The alloy precisely introduces Ta element in the Zr-20wt%Nb matrix to form a Zr-Nb-Ta alloy system; in the preparation, the Ta content is controlled and combined with three-stage solid solution-ageing quenching heat treatment to effectively stabilize the beta-Zr phase, and the synergistic optimization of the elastic modulus and strength of the alloy is realized. With the increase of the Ta content, the tensile strength of the alloy increases first and then decreases, and the elastic modulus decreases first and then increases; when the Ta content is optimal, the elastic modulus of the alloy is as low as 15.2 GPa, and the peak 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. In addition, the present application also has the advantages of simple and controllable preparation process, excellent biocompatibility of the alloy, and suitability for industrial application of high-end orthopedic implant materials.

[0006] The technical scheme of the present application is as follows:

[0007] An ultra-low elastic modulus biomedical zirconium alloy, which comprises three alloy elements, and the mass percentage content ratio of each is: Zr 71-80wt%, Nb 20wt%, Ta 1-9wt%, and the balance is inevitable impurities.

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

[0009] First step: vacuum arc melting

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

[0011] (2) The prepared raw materials are placed in the water-cooled copper crucible of the non-consumable vacuum arc melting furnace, the valve is closed, and high vacuum is extracted to-4.5~ -5*10-3Pa;

[0012] (3) -0.4~ -0.6Mpa of high-purity argon gas is filled into the arc furnace cavity, and then arc striking and melting are carried out, the melting current is 150~ 200A / S, the ingot alloy is obtained by repeatedly turning over and melting 5-6 times, and each time the melting time is 5-7 minutes;

[0013] Second step: three-stage quenching solid solution aging heat treatment process

[0014] (1) The melted ingot alloy is placed in a vacuum tube furnace, high-purity argon gas is introduced for 3-4 times of gas washing, and then the temperature is raised to 1050-1100℃ under the argon atmosphere, and the alloy is quenched after being kept for 2-5 hours;

[0015] (2) reheat to 900-1000℃, keep for 0.5-3 hours, quenching;

[0016] (3) finally heat to 300-400℃, keep for 0.5-3 hours, quenching, to obtain the ultra-low modulus biomedical zirconium alloy.

[0017] The preparation method of the ultra-low elastic modulus biomedical zirconium alloy, the pure Zr is an industrial grade sponge zirconium, the pure Nb is a particle with a purity of 99.9%, and the pure Ta is a particle with a purity of 99.9%.

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

[0019] The substantial features of the present application are:

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

[0021] In the Zr-20wt%Nb matrix, 1-9wt% Ta is accurately introduced. By synergistically regulating the β-Zr phase stability window through Ta / Nb, the tendency of high modulus brittle ω phase and α″ phase precipitation is effectively inhibited at the atomic scale (especially avoiding the subsequent processing difficulty or modulus rebound caused by β phase over-stabilization under high Ta content), which lays an irreplaceable component foundation for obtaining ultra-low elastic modulus (<20GPa).

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

[0023] The core innovation of the "three-stage quenching and solid solution aging" process lies in the specific temperature window combination and quenching steps, aiming to accurately control the β phase decomposition path and precipitated phase type / size:

[0024] (1) First high-temperature homogenization quenching (1050-1100℃ / 5h→quenching): the key is the ultra-high temperature, which completely eliminates the as-cast segregation and obtains a single β phase with high component uniformity.

[0025] (2) Second medium-temperature solid solution quenching (900-1000℃ / 2h→quenching): the key is the medium-temperature zone, which adjusts the β phase supersaturation, and obtains a specific supersaturation metastable β phase matrix after quenching.

[0026] (3) Tertiary low temperature aging quenching (300-400℃ / 2h→quenching): short time holding at very low temperature window to precisely induce high density, nanoscale ω phase precipitation (not α phase or coarse ω phase as commonly seen in traditional Zr alloys). Quenching operation is critical at this step, aiming to immediately freeze the microstructure, prevent ω phase from growing up or transforming to α phase during cooling, thus ensuring the dispersion of nanoscale ω strengthening phase, significantly improving the strength without significantly increasing the elastic modulus, and eliminating internal stress.

[0027] The beneficial effects of the present application are:

[0028] (1) Ultra-low elastic modulus

[0029] By precisely adding Ta element (1-9wt%) and adopting tertiary solution-aging quenching process, the average elastic modulus of the alloy can be reduced to 15.2 GPa (nanoindentation test, Figure 4 as shown), which is highly matched with human bone (7-30 GPa), effectively reducing the stress shielding effect after implantation. Compared with conventional Zr-2.5Nb heat treated alloy (elastic modulus > 70 GPa), the present application reduces by more than 78%.

[0030] (2) High tensile strength

[0031] After tertiary quenching heat treatment, the ultimate tensile strength (UTS) of the alloy can be as high as 864 MPa (tensile curve see Figure 3 ), which is about 54% higher than that of conventional Zr-2.5Nb (≈560 MPa). At the same time, the yield strength reaches 864 MPa, and the elongation after fracture is 10.95%, which is sufficient to meet the mechanical requirements of high-load orthopedic implants.

[0032] (3) Simple and controllable process, easy to industrialize

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

[0034] (4) Excellent biocompatibility

[0035] The selected alloy elements Zr / Nb / Ta are all medical grade materials, meeting the safety requirements of orthopedic implants. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 is the heat treatment process flowchart of the present application;

[0037] Figure 2 is the scanning topographic map of zirconium alloy of Examples 1-7 and Comparative Example 1;

[0038] Figure 3Tensile stress-strain curves of the zirconium alloys of Examples 1-7, Comparative Example 1;

[0039] Figure 4 Dynamic ultra-micro force displacement curves of the zirconium alloys of Examples 1-7, Comparative Example 1; DETAILED DESCRIPTION

[0040] The embodiments of the present application are further described in detail to make the technical process, the purpose of the application and the advantages of the application more clear.

[0041] The present application provides a kind of ultra-low elastic modulus high strength zirconium alloy and its preparation method, according to mass percentage, three kinds of element atom percentage are as follows: Zr 71-80wt%, Nb 20wt%, Ta 1-9wt%, the rest is inevitable impurity.

[0042] Nb and Ta elements introduced in the zirconium alloy of the present application are both non-toxic elements to human body, and are both β stable elements, the purpose is to obtain more β-Zr organization. β-Zr is cubic structure, more slip system than α-Zr (hexagonal close-packed), so as to achieve the purpose of reducing elastic modulus. In addition, the solid solution aging process of three-stage quenching, the first quenching is to eliminate melting defects, composition homogenization, and quenching to obtain saturated β phase; The second quenching is solid solution treatment, to improve the solid solution strength, and quenching to obtain supersaturated β phase; The purpose of the third quenching aging treatment is to precipitate nano ω phase, to improve the strength and prevent the nano phase from growing. Finally, a low modulus high strength biomedical zirconium alloy is obtained.

[0043] The present application also provides a kind of low density high strength zirconium alloy and its preparation method, comprising the following steps:

[0044] (1) the alloy raw material is melted by non-consumable vacuum arc to obtain ingot alloy;

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

[0046] The alloy raw material is melted by non-consumable vacuum arc to obtain ingot alloy. In the present application, the type of the alloy raw material is not specifically limited, and the alloy raw material known to those skilled in the art is used to obtain the target component of the zirconium alloy. The alloy raw material of the present application is industrial grade sponge zirconium, pure Ta particles and pure Nb particles. The present application does not have special requirements for the particle size of the raw material.

[0047] In the present application, the alloy raw materials are cleaned and dried before being melted. The alloy melting is preferably non-consumable vacuum arc melting, and the equipment used is a WK series vacuum arc furnace. The current of the non-consumable vacuum arc melting is preferably 130-210 A / S, and further preferably 170-200 A / S. The non-consumable vacuum arc melting is preferably carried out in an argon protective gas, and the pressure of the non-consumable vacuum arc melting protective gas is preferably -0.04 to -0.06 MPa. The amount of argon gas introduced is sufficient to meet the amount of ionized gas for arc melting. When using non-consumable vacuum arc melting, the present application preferably first draws the vacuum degree in the hearth to -5 x 10 -3 Pa, and then introduces argon gas. The number of repetitions of the non-consumable vacuum arc melting in the present application is preferably 5-8 times, and more preferably 7-8 times. The present application preferably carries out repeated face melting, and the melting process is carried out in a water-cooled copper crucible of a non-consumable vacuum melting furnace. The present application preferably waits for the ingot alloy to cool after each non-consumable vacuum melting is completed, and then turns over the cooled ingot alloy to continue the next non-consumable vacuum melting operation. In the present application, each independent non-consumable vacuum melting process is preferably 4-7 min, and more preferably 5-6 min. The repeated face melting non-consumable vacuum melting operation of the present application can ensure that the composition of the ingot alloy is more uniform. After obtaining the ingot alloy, the present application carries out homogenization annealing treatment on the ingot alloy to obtain a zirconium alloy ingot with uniform structure and composition.

[0048] In the present application, the three-stage quenching, solid solution and aging treatment is preferably carried out by a vacuum tube furnace. The annealing treatment preferably uses argon as a protective gas, and the annealing treatment temperatures are 1050-1100°C, preferably 1050°C; 900-1000°C, preferably 950°C; and 300-400°C, preferably 350°C, respectively. The holding times are 5, 2 and 2 hours, respectively.

[0049] In order to further illustrate the present application, the low-density high-toughness zirconium alloy and the preparation method thereof provided by the present application are described in detail below in conjunction with examples, but they should not be understood as limiting the scope of protection of the present application.

[0050] Comparative Example 1

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

[0052] (2) The prepared raw materials were placed in a water-cooled copper crucible of a non-consumable vacuum melting furnace, and high vacuum was drawn to -5 x 10 - 3Pa and below; the non-consumable vacuum arc melting furnace cavity was filled with argon with a purity of 99.999% until the pressure reading was between -0.04 MPa and -0.06 MPa, and then the melting operation was performed. After the arc was struck, the 20 g of pure zirconium ingot used for the extra arc striking was first melted for 5 min to consume the oxygen and nitrogen in the furnace, and then the target alloy was melted, with each melting lasting 5 min. The ingot was repeatedly flipped and melted for 8 times to obtain the ingot alloy. The melting current was between 160 and 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°C, held for five hours, and quenched. Then it was heated to 950°C, held for two hours, and quenched. Finally, it was heated to 350°C, held for two hours, and quenched. The heat-treated zirconium alloy ingot was obtained.

[0054] (4) The ingot was processed by an electric spark wire cutting machine to cut out samples of the required size for testing.

[0055] Example 1

[0056] (1) The Zr-20Nb-1Ta alloy was prepared according to the mass percentage. 78.9963 g of industrial-grade sponge zirconium (purity 99.5%), 20.0330 g of Nb particles with a purity of 99.9%, and 1.0006 g of Ta particles with a purity of 99.9 were taken. They were respectively placed in anhydrous ethanol and ultrasonically cleaned for 15 min.

[0057] (2) The prepared raw materials were placed in the water-cooled copper crucible of the non-consumable vacuum melting furnace, and high vacuum was extracted to -5 x 10 - 3 Pa and below; the non-consumable vacuum arc melting furnace cavity was filled with argon with a purity of 99.999% until the pressure reading was between -0.04 MPa and -0.06 MPa, and then the melting operation was performed. After the arc was struck, the 20 g of pure zirconium ingot used for the extra arc striking was first melted for 5 min to consume the oxygen and nitrogen in the furnace, and then the target alloy was melted, with each melting lasting 5 min. The ingot was repeatedly flipped and melted for 8 times to obtain the ingot alloy. The melting current was between 160 and 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°C, held for five hours, and quenched. Then it was heated to 950°C, held for two hours, and quenched. Finally, it was heated to 350°C, held for two hours, and quenched. The heat-treated zirconium alloy ingot was obtained.

[0059] (4) The ingot was processed by an electric spark wire cutting machine to cut out samples of the required size for testing.

[0060] Example 2

[0061] (1) The Zr-20Nb-2Ta alloy was dosed according to the mass percentage, 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% were taken. They were respectively placed in anhydrous ethanol and ultrasonically cleaned for 15min;

[0062] (2) The prepared raw materials were placed in the water-cooled copper crucible of the non-consumable vacuum melting furnace, and high vacuum was extracted to below-5x10-3Pa; pure argon with a purity of 99.999% was filled into the cavity of the non-consumable vacuum arc melting furnace until the pressure gauge was between-0.04MPa and-0.06MPa, and then the melting operation was carried out. After the arc was ignited, 20g of pure zirconium ingot used for arc ignition was melted for 5min to consume the oxygen and nitrogen in the furnace, and then the target alloy was melted, each time for 5min, and the ingot was repeatedly turned over and melted for 8 times to obtain the ingot alloy. The melting current was 160-200A / S.

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

[0064] (4) The ingot was processed by an electric spark wire cutting machine to cut out samples of the required size for subsequent testing.

[0065] Example 3

[0066] (1) The Zr-20Nb-3Ta alloy was dosed according to the mass percentage, 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% were taken. They were respectively placed in anhydrous ethanol and ultrasonically cleaned for 15min;

[0067] (2) The prepared raw materials were placed in the water-cooled copper crucible of the non-consumable vacuum melting furnace, and high vacuum was extracted to below-5x10-3Pa; pure argon with a purity of 99.999% was filled into the cavity of the non-consumable vacuum arc melting furnace until the pressure gauge was between-0.04MPa and-0.06MPa, and then the melting operation was carried out. After the arc was ignited, 20g of pure zirconium ingot used for arc ignition was melted for 5min to consume the oxygen and nitrogen in the furnace, and then the target alloy was melted, each time for 5min, and the ingot was repeatedly turned over and melted for 8 times to obtain the ingot alloy. The melting current was 160-200A / S.

[0068] (3) Put the ingot alloy into the vacuum tube furnace for heat treatment, first heated to 1050℃ under the atmosphere of argon with purity of 99.999%, holding for five hours, quenching; then heated to 950℃, holding for two hours, quenching; finally heated to 350℃, holding for two hours, quenching. The heat-treated zirconium alloy ingot is obtained.

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

[0070] Example 4

[0071] (1) The Zr-20Nb-4Ta alloy is dosed according to the mass percentage, taking 76.0000g of industrial-grade sponge zirconium, 20.0389g of Nb particles with purity of 99.9%, and 4.0032g of Ta particles with purity of 99.9%. They are respectively placed in anhydrous ethanol for ultrasonic cleaning for 15min;

[0072] (2) The prepared raw materials are placed in the water-cooled copper crucible of the non-consumable vacuum melting furnace, and high vacuum is extracted to below-5×10-3Pa; the non-consumable vacuum arc melting furnace cavity is filled with argon with purity of 99.999% until the pressure gauge is between-0.04MPa and-0.06MPa, and then the melting operation is carried out. After the arc is drawn, 20g of pure zirconium ingot used for arc drawing is melted for 5min to consume the oxygen and nitrogen in the furnace, and then the target alloy is melted, each time for 5min, and the ingot is repeatedly turned over for 8 times to obtain the ingot alloy. The melting current is 160-200A / S.

[0073] (3) Put the ingot alloy into the vacuum tube furnace for heat treatment, first heated to 1050℃ under the atmosphere of argon with purity of 99.999%, holding for five hours, quenching; then heated to 950℃, holding for two hours, quenching; finally heated to 350℃, holding for two hours, quenching. The heat-treated zirconium alloy ingot is obtained.

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

[0075] Example 5

[0076] (1) The Zr-20Nb-5Ta alloy is dosed according to the mass percentage, taking 75.0283g of industrial-grade sponge zirconium, 20.1302g of Nb particles with purity of 99.9%, and 5.0061g of Ta particles with purity of 99.9%. They are respectively placed in anhydrous ethanol for ultrasonic cleaning for 15min;

[0077] (2) Put the prepared raw materials into the water-cooled copper crucible of the non-consumable vacuum melting furnace, and extract high vacuum to below -5x10-3Pa; fill the non-consumable vacuum arc melting furnace cavity with argon with a purity of 99.999% until the pressure gauge is between -0.04MPa and -0.06MPa, and then perform the melting operation. After the arc is drawn, the 20g pure zirconium ingot used for drawing the arc is first melted for 5min to consume the oxygen and nitrogen in the furnace, and then the target alloy is melted, each time for 5min. The ingot is repeatedly turned over and melted for 8 times to obtain the ingot alloy. The melting current is between 160A / S and 200A / S.

[0078] (3) Put the ingot alloy into the vacuum tube furnace for heat treatment. Under the argon atmosphere with a purity of 99.999%, first heat to 1050℃, keep for five hours, quench; then heat to 950℃, keep for two hours, quench; finally heat to 350℃, keep for two hours, quench. The heat-treated zirconium alloy ingot is obtained.

[0079] (4) Process the ingot through the wire cut electrical discharge machine to cut out samples of the required size for subsequent testing.

[0080] Example 6

[0081] (1) Prepare the Zr-20Nb-7Ta alloy according to the mass percentage, take 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%. Respectively put into anhydrous ethanol and ultrasonic cleaning for 15min.

[0082] (2) Put the prepared raw materials into the water-cooled copper crucible of the non-consumable vacuum melting furnace, and extract high vacuum to below -5x10-3Pa; fill the non-consumable vacuum arc melting furnace cavity with argon with a purity of 99.999% until the pressure gauge is between -0.04MPa and -0.06MPa, and then perform the melting operation. After the arc is drawn, the 20g pure zirconium ingot used for drawing the arc is first melted for 5min to consume the oxygen and nitrogen in the furnace, and then the target alloy is melted, each time for 5min. The ingot is repeatedly turned over and melted for 8 times to obtain the ingot alloy. The melting current is between 160A / S and 200A / S.

[0083] (3) Put the ingot alloy into the vacuum tube furnace for heat treatment. Under the argon atmosphere with a purity of 99.999%, first heat to 1050℃, keep for five hours, quench; then heat to 950℃, keep for two hours, quench; finally heat to 350℃, keep for two hours, quench. The heat-treated zirconium alloy ingot is obtained.

[0084] (4) Process the ingot through the wire cut electrical discharge machine to cut out samples of the required size for subsequent testing.

[0085] Example 7

[0086] (1) The Zr-20Nb-9Ta alloy was prepared by mass percentage, 71.0025 g of industrial-grade sponge zirconium, 19.9984 g of Nb particles with a purity of 99.9%, and 9.0103 g of Ta particles with a purity of 99.9%. They were respectively placed in anhydrous ethanol and ultrasonically cleaned for 15 min;

[0087] (2) The prepared raw materials were placed in a water-cooled copper crucible of a non-consumable vacuum melting furnace, and high vacuum was extracted to below -5 x 10-3Pa; the non-consumable vacuum arc melting furnace cavity was filled with argon with a purity of 99.999% until the pressure gauge was between -0.04 MPa and -0.06 MPa, and then the melting operation was performed. After the arc was drawn, 20 g of pure zirconium ingot used for arc drawing was melted for 5 min to consume the oxygen and nitrogen in the furnace, and then the target alloy was melted, each time for 5 min, and the ingot was repeatedly turned over and melted for 8 times to obtain an ingot alloy. The melting current was 160-200 A / S.

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

[0089] (4) The ingot was processed by an electric spark wire cutting machine to cut out samples of the required size for subsequent testing.

[0090] The zirconium alloy samples prepared in Examples 1-7 and Comparative Example 1 were corroded by Kroll's corrosion solution (HF:HCl:HNO3:H2O = 1:1.5:2.5:95). Scanning electron microscopy (instrument model: JSM-7100F) was used for observation, and the scanning images are shown in Figure 2 From the figure, it can be seen that after adding Ta element to the Zr-20Nb alloy, the morphology changes. The microstructure in Example 2 is the most special, showing a banded structure, which may enhance its mechanical properties, and increase the number of slips during the strain process, thereby reducing the elastic modulus.

[0091] The tensile properties of the zirconium alloy samples prepared in Examples 1-7 and Comparative Example 1 were tested (instrument model: WDW-200). The stress-strain curves are shown in Figure 3The mechanical property parameters are shown in Table 1. In the figure, the strength of 1Ta and 2Ta is higher than that of the comparative example, and the highest strength is that of the Zr-20Nb-2Ta alloy of Example 2, which reaches 864 MPa, 64 MPa higher than that of the comparative example, and nearly 300 MPa higher than that of the common Zr-2.5Nb alloy, reaching the strength requirement of artificial implant alloy. With further increase of the Ta content, the strength decreases. This is because the addition of a small amount of Ta has a solid solution strengthening effect on the zirconium alloy, and when the Ta content is further increased, the supersaturated Ta element becomes a defect of the alloy mechanical property test, reducing the strength.

[0092] The zirconium alloy samples prepared in Examples 1-7 and Comparative Example 1 were subjected to microhardness testing (instrument model: HMV-2T). The experimental results are shown in Table 1. The hardness value change trend shows a certain similarity with the strength. The hardness value of 2Ta is higher, which is 355 HV. Subsequently, with the increase of the Ta content, the hardness value decreases to a certain extent.

[0093] The zirconium alloy samples prepared in Examples 1-7 and Comparative Example 1 were subjected to dynamic ultramicroelastic modulus testing (instrument model: DUH-211S). The force-displacement curve is shown in Figure 4 The mechanical property parameters are shown in Table 1. In the figure, the slope of 2Ta is obviously lower than that of other alloys, and the modulus is only 15.2 GPa. The elastic modulus of human bone is 7-30 GPa, which completely matches the modulus of human bone and reduces the stress shielding.

[0094] Table 1 Comparison table of mechanical property parameters

[0095]

[0096] The present application is described by examples, but does not limit the present application. Referring to the description of the present application, other changes in the disclosed examples are easily guessed by researchers in the field of zirconium alloys, and such changes should be within the scope defined in the present application.

[0097] The remaining matters of the present application are known technologies.

Claims

1. A biomedical zirconium alloy with an ultra-low elastic modulus, characterized by: The alloy comprises the following components in percentage by weight: Zr 71-80wt%, Nb 20wt%, Ta 1-9wt%, and the remainder being inevitable impurities.

2. The method for preparing the ultra-low elastic modulus biomedical zirconium alloy according to claim 1, wherein: The following steps are involved: 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 a water-cooled copper crucible in a non-consumable vacuum arc melting furnace, close the valve, and evacuate to a high vacuum of -4.5 to -5×10-3Pa; (3) Filling the arc furnace cavity with high-purity argon gas at -0.4 to -0.6 MPa, then striking the arc and melting, with a melting current of 150 to 200 A / S, repeatedly turning over and melting for 5 to 6 times, each melting for 5 to 7 minutes, to obtain an ingot alloy; Step 2: Three-stage quenching and solution aging heat treatment process (1) Place the smelted ingot alloy into a vacuum tube furnace, introduce high-purity argon gas for 3-4 times of purge, then heat to 1050-1100°C in an argon atmosphere, keep warm for 2-5 hours, and quench; (2) Heat up to 900-1000°C, keep warm for 0.5-3 hours, and quench; (3) Finally, the temperature is raised to 300-400°C, kept at this temperature for 0.5-3 hours, and quenched to obtain an ultra-low modulus biomedical zirconium alloy.

3. The method for preparing the ultra-low elastic modulus biomedical zirconium alloy according to claim 2, wherein: The pure Zr is industrial-grade sponge zirconium, the purity of pure Nb is 99.9%, and the purity of pure Ta is 99.9%.

4. The method for preparing the ultra-low elastic modulus biomedical zirconium alloy according to claim 2, wherein: The purity of high-purity argon is 99.999%.

Images