Gap oxygen-doped ti-zr-nb-al medium-entropy alloy, preparation method and application thereof

Abstract

The application provides a gap oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with a superhard oxide layer, and an expression is as follows: (Ti a Zr b Nb c Al d ) 100‑e O e , 40 at.%≤a≤50 at.%, 36 at.%≤b≤45 at.%, 3 at.%≤c≤17at.%, 1 at.%≤d≤7 at.%, 0.5 at.%≤e≤2.0 at.%, a+b+c+d=100 at.%. A preparation method comprises the following steps: mixing raw materials, smelting to prepare a cast ingot, polishing after wire cutting, and polishing to obtain the gap oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with the superhard oxide layer. Then, the gap oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with the superhardoxide layer is obtained by heat oxidation for 6h under the condition that the temperature is 500 DEG C and the air atmosphere is air, and natural cooling to room temperature. An application is also provided, and is used for medical orthopedic implant materials. The gap oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with the superhard oxide prepared by the application has a low elastic modulus, the surface of the alloy in an oxidized state has superhigh hardness, has good wear resistance, and can be used for medical orthopedic implant materials.

Description

Technical Field

[0001] This invention belongs to the field of medium-entropy alloy technology, specifically relating to a Ti-Zr-Nb-Al medium-entropy alloy with an interstitial oxygen-doped superhard oxide layer, its preparation method, and its application. Background Technology

[0002] Metallic materials, due to their high strength and toughness, fatigue resistance, ease of processing and forming, and reliable clinical use, were first used as orthopedic implant materials and are now widely used in clinical practice. Titanium alloys are renowned for their excellent specific strength, corrosion resistance, and biocompatibility, making them a preferred third-generation metallic material for bone implants. Among them, β-type titanium alloys (including fully β-type, metastable β-type, and near-β-type) with the addition of non-toxic β-structure stabilizing elements (such as Nb, Fe, Zr, Mo, and Ta) have seen rapid development. The main advantage of this alloy is its lower elastic modulus compared to other types of titanium alloys, which helps reduce stress shielding effects and promotes bone repair and reconstruction. Currently, various countries have prepared a series of low-elasticity β-titanium alloys such as Ti-Nb-(X), Ti-Mo-(X), and Ti-Ta-(X). However, the application of low-elasticity β-type medical titanium alloys, represented by the Ti-Nb-(X) system, is still hampered by the following bottlenecks: ① The elastic modulus and yield strength of the alloy are mismatched, that is, the strength decreases significantly as the elastic modulus decreases; ② The alloy processing technology is immature and the processing cost is high; ③ The alloy properties are highly sensitive to impurity elements.

[0003] In recent years, high- and medium-entropy alloys (also known as multi-component solid solution alloys or multi-principal element alloys) with three or more main elements and synergistic property control have attracted widespread attention due to their excellent strength, toughness, fatigue resistance, corrosion resistance, and phase stability. As rapidly developing new materials, high- and medium-entropy alloys have significant advantages such as tunable elastic modulus due to complex interatomic forces, excellent strength due to solid solution strengthening and ordered strengthening through oxygen interstitial structures, and deformation continuity due to stable phase structures, which are expected to find suitable applications in the biomedical field. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address the shortcomings of the prior art by providing an interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultra-hard oxide layer, its preparation method and application. This alloy has a low elastic modulus, an ultra-high hardness on the oxide surface, and good wear resistance, and can be used as a medical orthopedic implant material.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: an interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultra-hard oxide layer, wherein the expression of the interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultra-hard oxide layer is: (Ti a Zr bNb c Al d ) 100-e O e , 40 at.%≤a≤50 at.%, 36 at.%≤b≤45 at.%, 3 at.%≤c≤17 at.%, 1 at.%≤d≤7 at.%, 0.5 at.%≤e≤2.0 at.%, a+b+c+d=100 at.%; The preparation method of the interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultra-hard oxide layer is as follows:

[0006] S1. Mix industrial pure titanium TA1 particles, industrial pure zirconium Zr-1 particles, industrial pure niobium Nb1 particles, ZrO2 particles, and pure Al particles, and prepare ingots by electric arc furnace melting or vacuum suspension melting.

[0007] The industrial pure titanium TA1 particles contain Ti ≥ 99.5 wt.%, the industrial pure zirconium Zr-1 particles contain Zr+Hf ≥ 99.2 wt.%, the industrial grade niobium Nb1 particles contain Nb ≥ 99.9 wt.%, the ZrO2 particles have a purity ≥ 99.9 wt.%, and the Al particles have a purity ≥ 99.0 wt.%.

[0008] In this invention, oxygen atoms can enter the interstitial spaces of the crystal lattice to form ordered interstitial atom complexes, thereby enhancing the overall performance of the alloy. The alloy is designed based on a Ti-Zr-Nb base alloy with the addition of a small amount of Al. In the Ti-Zr-Nb base alloy, the content of Ti and Zr is relatively high, while the content of Nb is relatively low, in order to ensure the elastic modulus of the alloy. It is generally believed that the lower the mixed VEC (valence electron concentration) of the alloy, the lower the elastic modulus of the alloy. The VEC of Ti and Zr is 4, and the VEC of Nb is 5. Nb is an indispensable element for stabilizing the BCC structure, hence the above ratio was adopted. The atomic radius of Al is similar to that of Ti and Zr alloys, which can suppress the formation of brittle intermediate phases. Moreover, the Al content is lower than that in Ti6Al4V (the biomedical Ti alloy currently widely used in clinical practice), which is an acceptable tolerance level for the human body.

[0009] S2. The ingot obtained in S1 is cut into cuboid blocks by wire cutting, and then polished with 400#, 800#, 1500#, 2000# and 3000# sandpaper in sequence. Finally, it is polished and then thermally oxidized in an air atmosphere at 500℃ for 6 hours to produce an ultra-hard oxide film on its surface. After naturally cooling to room temperature, an interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultra-hard oxide layer is obtained.

[0010] Preferably, the electric arc furnace melting method described in S1 is as follows: pure Al particles, industrial pure titanium TA1 particles, ZrO2 particles, industrial pure zirconium Zr-1 particles, and industrial pure niobium Nb1 particles are sequentially placed into a copper crucible, and the vacuum degree is evacuated to 3.7 × 10⁻⁶. -3 Pa, purge with high-purity argon gas to 0.05 MPa, the current during melting is 450 A to 550 A, each melting session lasts 3 minutes, after which the melting is water-cooled for 8 minutes, then turned over and melting continues for a total of 6 to 8 times. The molten alloy is then poured into a copper mold and water-cooled to obtain an ingot.

[0011] The vacuum suspension melting method is as follows: pure Al particles, industrial pure titanium T1 particles, ZrO2 particles, industrial pure zirconium Zr-1 particles, and industrial pure niobium Nb1 particles are sequentially placed into a copper crucible, and the vacuum degree is evacuated to 3.7 × 10⁻⁶. -3 The pressure is increased by 0.05 MPa with high-purity argon gas, and the power is increased at a rate of 0.5 kW / min until all particles are completely melted. The temperature is held for 30 min, and then the power is decreased at a rate of 1.5 kW / min until the alloy cools and solidifies to obtain an ingot.

[0012] Preferably, the yield strength of the ingot in S1 is 571 MPa to 820 MPa, and the elastic modulus is 45 GPa to 69 GPa; the hardness of the interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultra-hard oxide layer in S2 is 1010 HV. 0.2 ~1040 HV 0.2 .

[0013] The alloy prepared by this invention has a low elastic modulus, high strength, and ultra-high hardness, and can be applied to biomedical materials.

[0014] This invention also provides the application of the interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultra-hard oxide layer prepared by the above preparation method, wherein the interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultra-hard oxide layer is used as a medical orthopedic implant material.

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] The interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultra-hard oxide layer prepared by this invention has a low elastic modulus, moderate strength, and an ultra-high hardness on its oxide surface, making it suitable for medical orthopedic implant materials such as bone plates, bone screws, bone pins, and bone rods. This alloy uses industrial raw materials instead of high-purity raw materials, significantly reducing costs, and the alloy smelting method is simple and reliable. Furthermore, through simple oxidation heat treatment, an ultra-hard oxide film can be formed on the alloy surface, increasing wear resistance; this characteristic expands the alloy's application range to the joint field.

[0017] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. Attached Figure Description

[0018] Figure 1 The images show the XRD patterns of interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloys with ultra-hard oxide layers prepared in Examples 1-3 of this invention.

[0019] Figure 2 The images show the XRD patterns of interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloys with ultra-hard oxide layers prepared in Examples 4-6 of this invention.

[0020] Figure 3 These are the room temperature tensile stress-strain curves of the interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloys with ultra-hard oxide layers prepared in Examples 1-3 of this invention.

[0021] Figure 4 These are the room temperature tensile stress-strain curves of the interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloys with ultra-hard oxide layers prepared in Examples 4-6 of this invention.

[0022] Figure 5 These are the XRD patterns of the interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloys with ultra-hard oxide layers prepared in Examples 2-3 of this invention during room temperature tensile testing.

[0023] Figure 6 These are oxidation time-hardness curves at different temperatures (400℃, 450℃, 500℃) during the preparation of the medium-entropy alloy prepared in Example 1 of this invention.

[0024] Figure 7 The image shows the wear depth curve of the 1&O# medium-entropy alloy (oxidized at 500℃ for 6 hours) prepared in Example 1 of this invention. The inset at the top is the wear depth curve of the 1# medium-entropy alloy. Detailed Implementation

[0025] The raw material used in the embodiments of the present invention, industrial pure titanium TA1 particles (Ti≥99.5 wt.%), was purchased commercially from Baoji Zhongliyang Metal Co., Ltd.

[0026] Industrial-grade pure zirconium Zr-1 particles (Zr+Hf≥99.2 wt.%), purchased commercially from Baoji Zhongliyang Metal Co., Ltd.

[0027] Industrial-grade niobium Nb1 particles (Nb≥99.9 wt.%), purchased commercially from Baoji Zhongliyang Metal Co., Ltd.

[0028] ZrO2 granules (purity ≥99.9 wt.%), purchased commercially from Baoji Zhongliyang Metal Co., Ltd.

[0029] Al granules (purity ≥99.9 wt.%), purchased commercially from Baoji Zhongliyang Metal Co., Ltd.

[0030] Each raw material is descaled and ultrasonically cleaned with industrial ethanol. Example 1

[0031] This embodiment features an interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultra-hard oxide layer. The expression for this interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultra-hard oxide layer is: (Ti a Zr b Nb c Al d ) 100-e O e , a=45 at. %, b=45 at. %, c=9 at. %, d=1 at. %, e=0.5 at. %, named (Ti 45 Zr 45 Nb9Al1) 99.5 O 0.5 .

[0032] This embodiment also provides a method for preparing the above-mentioned interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultrahard oxide layer, the method being:

[0033] S1. Mix industrial pure titanium TA1 particles, industrial pure zirconium Zr-1 particles, industrial pure niobium Nb1 particles, ZrO2 particles, and pure Al particles, and then melt them in an electric arc furnace to prepare an ingot.

[0034] The electric arc furnace smelting method is as follows: pure Al particles, industrial pure titanium TA1 particles, ZrO2 particles, industrial pure zirconium Zr-1 particles, and industrial pure niobium Nb1 particles are sequentially placed into a copper crucible, and the vacuum degree is evacuated to 3.7 × 10⁻⁶. -3 Pa, high-purity argon gas was purged to 0.05MPa, the current was 500 A during melting, each melting session lasted 3 minutes, and after each melting session, it was water-cooled for 8 minutes. After flipping, the melting continued for a total of 6 times. The molten alloy was poured into a copper mold and cooled with water to obtain an ingot, which was designated as No. 1 medium entropy alloy.

[0035] S2. The ingot obtained in S1 is cut into cuboid blocks by wire cutting, and then polished with 400#, 800#, 1500#, 2000# and 3000# sandpaper in sequence. Finally, it is polished and then thermally oxidized in an air atmosphere at 500℃ for 6 hours. After naturally cooling to room temperature, an interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultra-hard oxide layer is obtained, denoted as 1&O# medium-entropy alloy.

[0036] In this embodiment, the yield strength of the ingot (1# medium-entropy alloy) before oxidation is 685 MPa, and the elastic modulus is 54 GPa; the hardness of the interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultra-hard oxide layer prepared after oxidation is 1040 HV. 0.2 . Example 2

[0037] This embodiment features an interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultra-hard oxide layer. The expression for this interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultra-hard oxide layer is: (Ti a Zr b Nb c Al d ) 100-e O e , a=45 at.%, b=45 at. %, c=5 at. %, d=5 at. %, e=0.5 at. %, that is (Ti 45 Zr 45 Nb5Al5) 99.5 O 0.5 .

[0038] This embodiment also provides a method for preparing the above-mentioned interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultrahard oxide layer, the method being:

[0039] S1. Mix industrial pure titanium TA1 particles, industrial pure zirconium Zr-1 particles, industrial pure niobium Nb1 particles, ZrO2 particles, and pure Al particles, and then melt them in an electric arc furnace to prepare an ingot.

[0040] The electric arc furnace smelting method is as follows: pure Al particles, industrial pure titanium TA1 particles, ZrO2 particles, industrial pure zirconium Zr-1 particles, and industrial pure niobium Nb1 particles are sequentially placed into a copper crucible, and the vacuum degree is evacuated to 3.7 × 10⁻⁶. -3 Pa, high-purity argon gas was purged to 0.05MPa, the current was 550 A during melting, each melting session lasted 3 minutes, and after each melting session, it was water-cooled for 8 minutes. After flipping, the melting continued for a total of 8 times. The molten alloy was poured into a copper mold and cooled with water to obtain an ingot, which was designated as No. 2 medium entropy alloy.

[0041] S2. The ingot obtained in S1 is cut into cuboid blocks by wire cutting, and then polished with 400#, 800#, 1500#, 2000# and 3000# sandpaper in sequence. Finally, it is polished and then thermally oxidized in an air atmosphere at 500℃ for 6 hours. After naturally cooling to room temperature, an interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultra-hard oxide layer is obtained, denoted as 2&O# medium-entropy alloy.

[0042] In this embodiment, the yield strength of the ingot (2# medium-entropy alloy) before oxidation is 660 MPa, and the elastic modulus is 69 GPa; the hardness of the interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultra-hard oxide layer prepared after oxidation is 1020 HV. 0.2 . Example 3

[0043] This embodiment features an interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultra-hard oxide layer. The expression for this interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultra-hard oxide layer is: (Ti a Zr b Nb c Al d ) 100-e O e , a=45 at.%, b=45 at. %, c=3 at. %, d=7 at. %, e=0.5 at. %, that is (Ti 45 Zr 45 Nb3Al7) 99.5 O 0.5 .

[0044] This embodiment also provides a method for preparing the above-mentioned interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultrahard oxide layer, the method being:

[0045] S1. Mix industrial pure titanium TA1 particles, industrial pure zirconium Zr-1 particles, industrial pure niobium Nb1 particles, ZrO2 particles, and pure Al particles, and prepare ingots using vacuum suspension melting.

[0046] The vacuum suspension melting method is as follows: pure Al particles, industrial pure titanium T1 particles, ZrO2 particles, industrial pure zirconium Zr-1 particles, and industrial pure niobium Nb1 particles are sequentially placed into a copper crucible, and the vacuum degree is evacuated to 3.7 × 10⁻⁶. -3 Pa, purge high-purity argon gas to 0.05 MPa, increase the power at a rate of 0.5 kW / min until all particles are completely melted, hold at this temperature for 30 min, and then decrease the power at a rate of 1.5 kW / min until the alloy cools and solidifies, obtaining an ingot, denoted as No. 3 medium entropy alloy;

[0047] S2. The ingot obtained in S1 is cut into cuboid blocks by wire cutting, and then polished with 400#, 800#, 1500#, 2000# and 3000# sandpaper in sequence. Finally, it is polished and then thermally oxidized in an air atmosphere at 500℃ for 6 hours. After naturally cooling to room temperature, an interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultra-hard oxide layer is obtained, denoted as 3&O# medium-entropy alloy.

[0048] In this embodiment, the yield strength of the ingot (3# medium-entropy alloy) before oxidation is 571 MPa, and the elastic modulus is 45 GPa; the hardness of the interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultra-hard oxide layer prepared after oxidation is 1010 HV. 0.2 .

[0049] Example 4

[0050] This embodiment features an interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultra-hard oxide layer. The expression for this interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultra-hard oxide layer is: (Ti a Zr b Nb c Al d )100-eOe, a=40at.%, b=40at.%, c=17at.%, d=3at.%, e=1at.%, that is (Ti 40 Zr 40 Nb 17 Al3) 99 O1.

[0051] This embodiment also provides a method for preparing the above-mentioned interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultrahard oxide layer, the method being:

[0052] S1. Mix industrial pure titanium TA1 particles, industrial pure zirconium Zr-1 particles, industrial pure niobium Nb1 particles, ZrO2 particles, and pure Al particles, and melt them in an electric arc furnace to prepare an ingot, which is designated as No. 4 medium entropy alloy.

[0053] The electric arc furnace smelting method is as follows: pure Al particles, industrial pure titanium TA1 particles, ZrO2 particles, industrial pure zirconium Zr-1 particles, and industrial pure niobium Nb1 particles are sequentially placed into a copper crucible, and the vacuum degree is evacuated to 3.7 × 10⁻⁶. -3 Pa, high-purity argon gas is purged to 0.05MPa, the current is 500 A during melting, each melting session lasts 3 minutes, and after each melting session, it is water-cooled for 8 minutes. After flipping, melting continues, and a total of 7 melting sessions are performed. The molten alloy is then poured into a copper mold and water-cooled to obtain an ingot.

[0054] S2. The ingot obtained in S1 is cut into cuboid blocks by wire cutting, and then polished with 400#, 800#, 1500#, 2000# and 3000# sandpaper in sequence. Finally, it is polished and then thermally oxidized in an air atmosphere at 500℃ for 6 hours. After naturally cooling to room temperature, an interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultra-hard oxide layer is obtained, denoted as 4&O# medium-entropy alloy.

[0055] In this embodiment, the yield strength of the ingot (4# medium-entropy alloy) before oxidation is 650 MPa, and the elastic modulus is 67 GPa; the hardness of the interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultra-hard oxide layer prepared after oxidation is 1010 HV. 0.2 . Example 5

[0056] This embodiment features an interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultra-hard oxide layer. The expression for this interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultra-hard oxide layer is: (Ti a Zr b Nb c Al d )100-eOe, a=50at.%, b=40at.%, c=7at.%, d=3at.%, e=1at.%, that is (Ti 50 Zr 40 Nb7Al3) 99 O1.

[0057] This embodiment also provides a method for preparing the above-mentioned interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultrahard oxide layer, the method being:

[0058] S1. Mix industrial pure titanium TA1 particles, industrial pure zirconium Zr-1 particles, industrial pure niobium Nb1 particles, ZrO2 particles, and pure Al particles, and melt them in an electric arc furnace to prepare an ingot, which is denoted as 5# medium entropy alloy.

[0059] The electric arc furnace smelting method is as follows: pure Al particles, industrial pure titanium TA1 particles, ZrO2 particles, industrial pure zirconium Zr-1 particles, and industrial pure niobium Nb1 particles are sequentially placed into a copper crucible, and the vacuum degree is evacuated to 3.7 × 10⁻⁶. -3 Pa, high-purity argon gas is purged to 0.05MPa, the current is 550 A during melting, each melting session lasts 3 minutes, and after each melting session, it is water-cooled for 8 minutes. After flipping, melting continues, and a total of 6 melting sessions are performed. The molten alloy is then poured into a copper mold and water-cooled to obtain an ingot.

[0060] S2. The ingot obtained in S1 is cut into cuboid blocks by wire cutting, and then polished with 400#, 800#, 1500#, 2000# and 3000# sandpaper in sequence. Finally, it is polished and then thermally oxidized in an air atmosphere at 500℃ for 6 hours. After naturally cooling to room temperature, an interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultra-hard oxide layer is obtained, denoted as 5&O# medium-entropy alloy.

[0061] In this embodiment, the yield strength of the ingot (5# medium-entropy alloy) before oxidation is 703 MPa, and the elastic modulus is 56 GPa; the hardness of the interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultra-hard oxide layer prepared after oxidation is 1030 HV. 0.2 . Example 6

[0062] This embodiment features an interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultra-hard oxide layer. The expression for this interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultra-hard oxide layer is: (Ti a Zr b Nb c Al d ) 100-e O e , a=50 at.%, b=36 at. %, c=10 at. %, d=4 at. %, e=2 at. %, that is (Ti 50 Zr 36 Nb 10 Al4) 98 O2.

[0063] This embodiment also provides a method for preparing the above-mentioned interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultrahard oxide layer, the method being:

[0064] S1. Mix industrial pure titanium TA1 particles, industrial pure zirconium Zr-1 particles, industrial pure niobium Nb1 particles, ZrO2 particles, and pure Al particles, and melt them in an electric arc furnace to prepare an ingot, which is denoted as 6# medium entropy alloy.

[0065] The electric arc furnace smelting method is as follows: pure Al particles, industrial pure titanium TA1 particles, ZrO2 particles, industrial pure zirconium Zr-1 particles, and industrial pure niobium Nb1 particles are sequentially placed into a copper crucible, and the vacuum degree is evacuated to 3.7 × 10⁻⁶. -3 Pa, high-purity argon gas is purged to 0.05MPa, the current is 450 A during melting, each melting session lasts 3 minutes, and after each melting session, it is water-cooled for 8 minutes. After flipping, melting continues, and a total of 6 melting sessions are performed. The molten alloy is then poured into a copper mold and water-cooled to obtain an ingot.

[0066] S2. The ingot obtained in S1 is cut into cuboid blocks by wire cutting, and then polished with 400#, 800#, 1500#, 2000# and 3000# sandpaper in sequence. Finally, it is polished and then thermally oxidized in an air atmosphere at 500℃ for 6 hours. After naturally cooling to room temperature, an interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultra-hard oxide layer is obtained, denoted as 6&O# medium-entropy alloy.

[0067] In this embodiment, the yield strength of the ingot (6# medium-entropy alloy) before oxidation is 820 MPa, and the elastic modulus is 68 GPa; the hardness of the interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultra-hard oxide layer prepared after oxidation is 1035 HV. 0.2 . Example 7

[0068] This embodiment describes the microstructure and performance testing of interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloys (1# to 6# medium-entropy alloys) with ultra-hard oxide layers prepared in Examples 1-6. The interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloys with ultra-hard oxide layers of the present invention are used as medical orthopedic implant materials.

[0069] (1) Phase structure of the alloy

[0070] Phase analysis of the medium-entropy alloy was performed using an X-ray diffractometer with a scanning step size of 0.02 and a scanning rate of 5° / min.

[0071] The XRD patterns of the No. 1, No. 2, and No. 3 medium-entropy alloys prepared in Examples 1-3 of this invention are as follows: Figure 1 As shown, the XRD patterns of the 4#, 5#, and 6# medium-entropy alloys prepared in Examples 4-6 are as follows. Figure 2 As shown. The 1# medium-entropy alloy has a β structure, the 2# and 3# medium-entropy alloys contain a large amount of β structure and a small amount of orthorhombic martensite α" structure, and the 4#, 5# and 6# medium-entropy alloys have a β structure.

[0072] (2) Room temperature tensile properties and phase transformation

[0073] The interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloys with ultra-hard oxide layers prepared in each embodiment were cut into plate-shaped proportional (proportional coefficient k=5.65) tensile specimens. The engineering stress-strain curves of alloys #1, #2, and #3 were obtained by room temperature tensile testing on a universal testing machine equipped with a video extensometer at a strain rate of 0.001 s⁻¹. Figure 3 The engineering stress-strain curves of alloys #4, #5, and #6 are shown below. Figure 4 As shown.

[0074] The true stress-strain curves of all alloys show that no obvious yield plateau was observed during tensile testing, and all yield strengths were at... For accuracy, the yield strengths of alloys #1, #2, #3, #4, #5, and #6 are 685 MPa, 660 MPa, 571 MPa, 650 MPa, 703 MPa, and 820 MPa, respectively, and their elastic moduli are 54 GPa, 69 GPa, 45 GPa, 67 GPa, 56 GPa, and 68 GPa, respectively. All alloys have elastic moduli lower than that of Ti6Al4V alloy (~110 GPa) while maintaining high tensile strength. This helps to address the mismatch between the alloys and human bone, i.e., "stress shielding."

[0075] During the tensile process, medium-entropy alloys #1, #4, #5, and #6 showed no phase transformation at room temperature, while only medium-entropy alloys #2 and #3 underwent phase transformations. Their XRD patterns during the tensile process are shown below. Figure 5 As shown.

[0076] XRD patterns show that the 2# and 3# medium-entropy alloys underwent a phase transformation during stretching, and the alloy structure changed from a composite structure of a large number of β and a small number of α" to a composite structure of a large number of α' / α and a small number of α".

[0077] In each embodiment, the difference in yield strength and elastic modulus before and after oxidation (the ingot prepared in step S1 and the interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultra-hard oxide layer obtained after oxidation in step S2) is negligible. During the thermal oxidation process at 500℃ for 6 hours, the alloy microstructure remains almost unchanged. Furthermore, the oxide layer on the alloy surface is relatively thin, approximately 13 μm. Therefore, at this temperature, the yield strength and elastic modulus of the alloy are almost unaffected.

[0078] 3) Properties of Oxidized Alloys

[0079] A. Hardness

[0080] While preparing the No. 1 medium-entropy alloy in Example 1, the oxidation temperature and time in step S2 of the preparation method in Example 1 were optimized. Specifically, in addition to the initial oxidation at 500℃ for 6 hours in step S2, optimization experiments were also conducted at temperatures of 400℃, 450℃, and 500℃, with oxidation times of 3 hours and 6 hours. The surface hardness of the prepared medium-entropy alloy as a function of oxidation and time is shown in the curves below. Figure 6 As shown. Among them, the 1&O# medium-entropy alloy oxidized at 500℃ exhibits extremely high hardness, with a hardness of 267 HV. 0.2 (0h, before oxidation) Increased to 1040 HV 0.2 (6h). Furthermore, in Examples 2-6, after oxidation at 500℃ for 6 hours, the hardness all exceeded 1000 HV. 0.2 .

[0081] B. Wear resistance

[0082] The No. 1 medium-entropy alloy prepared after oxidation at 500℃ for 6 hours in Example 1 was used for tribological tests. The tribological tests were conducted on a UMT-Tribolab series tribometer. During friction, the sliding frequency was 1 Hz, the load was 3 N, and the friction time was 30 min. The grinding material was silicon nitride microspheres. The wear depth curve of the No. 1 medium-entropy alloy prepared after oxidation at 500℃ for 6 hours is shown below. Figure 7 As shown, the upper inset plot is the wear depth curve of the No. 1 medium-entropy alloy before oxidation (i.e., the ingot prepared in step S1).

[0083] The wear depth of the 1&O# medium-entropy alloy after oxidation is significantly reduced compared to that before oxidation, and the wear depth of the 1&O# medium-entropy alloy after oxidation is even smaller than that of Ti6Al4V(TC4) after oxidation at 500℃ for 6 hours.

[0084] This invention presents a novel Ti-Zr-Nb-Al medium-entropy alloy, innovatively incorporating interstitial oxygen. This alloy exhibits high tensile strength and low elastic modulus. Compared to existing medical-grade Ti6Al4V and β-titanium alloys, this alloy possesses higher strength and lower elastic modulus, covering a wide range of orthopedic implant applications (bone plates, screws, pins, rods). Compared to other medical-grade high- and medium-entropy alloys, this alloy uses industrial raw materials instead of high-purity raw materials, significantly reducing costs, and its smelting method is simple and reliable. Furthermore, through simple oxidation heat treatment, an ultra-hard oxide film can be formed on the alloy surface, increasing wear resistance. This feature expands the alloy's application range to the joint field.

[0085] 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 inventive essence shall still fall within the protection scope of the present invention.

Claims

1. A Ti-Zr-Nb-Al medium-entropy alloy with an interstitial oxygen-doped superhard oxide layer, characterized in that, The expression for the interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultra-hard oxide layer is: (Ti a Zr b Nb c Al d ) 100-e O e , 40 at.%≤a≤50 at.%, 36 at.%≤b≤45 at.%, 3 at.%≤c≤17 at.%, 1 at.%≤d≤7 at.%, 0.5at.%≤e≤2.0 at.%, a+b+c+d=100 at.%; The preparation method of the interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultra-hard oxide layer is as follows: S1. Mix industrial pure titanium TA1 particles, industrial pure zirconium Zr-1 particles, industrial pure niobium Nb1 particles, ZrO2 particles, and pure Al particles, and prepare ingots by electric arc furnace melting or vacuum suspension melting. The industrial pure titanium TA1 particles contain Ti ≥ 99.5 wt.%, the industrial pure zirconium Zr-1 particles contain Zr+Hf ≥ 99.2 wt.%, the industrial grade niobium Nb1 particles contain Nb ≥ 99.9 wt.%, the ZrO2 particles have a purity ≥ 99.9 wt.%, and the Al particles have a purity ≥ 99.0 wt.%. S2. The ingot obtained in S1 is cut into cuboid blocks by wire cutting, and then polished with 400#, 800#, 1500#, 2000# and 3000# sandpaper in sequence. Finally, it is polished and then thermally oxidized in an air atmosphere at 500℃ for 6 hours. After naturally cooling to room temperature, an interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultra-hard oxide layer is obtained.

2. The interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultra-hard oxide layer according to claim 1, characterized in that, The electric arc furnace smelting method described in S1 is as follows: pure Al particles, industrial pure titanium TA1 particles, ZrO2 particles, industrial pure zirconium Zr-1 particles, and industrial pure niobium Nb1 particles are sequentially placed into a copper crucible, and the vacuum degree is evacuated to 3.7 × 10⁻⁶. -3 Pa, purge with high-purity argon gas to 0.05 MPa, the current during melting is 450 A to 550 A, each melting session lasts 3 minutes, after which the melting is water-cooled for 8 minutes, then turned over and melting continues for a total of 6 to 8 times. The molten alloy is then poured into a copper mold and water-cooled to obtain an ingot. The vacuum suspension melting method is as follows: pure Al particles, industrial pure titanium TA1 particles, ZrO2 particles, industrial pure zirconium Zr-1 particles, and industrial pure niobium Nb1 particles are sequentially placed into a copper crucible, and the vacuum degree is evacuated to 3.7 × 10⁻⁶. -3 The pressure is increased by 0.05 MPa with high-purity argon gas, and the power is increased at a rate of 0.5 kW / min until all particles are completely melted. The temperature is maintained for 30 min, and then the power is decreased at a rate of 1.5 kW / min until the alloy cools and solidifies to obtain an ingot.

3. The interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultra-hard oxide layer according to claim 1, characterized in that, The yield strength of the ingot described in S1 is 571 MPa to 820 MPa, and the elastic modulus is 45 GPa to 69 GPa; the hardness of the interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultra-hard oxide layer described in S2 is 1010 HV. 0.2 ~1040HV 0.2 .

4. An application of an interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultra-hard oxide layer as described in any one of claims 1-3, characterized in that, The interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with an ultra-hard oxide layer is used as a medical orthopedic implant material.

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