Interstitial oxygen doped Ti-Zr-Nb-Al medium-entropy alloy and preparation method and application thereof

Abstract

The invention provides an interstitial oxygen doped Ti-Zr-Nb-Al medium-entropy alloy with a superhard oxide layer, and the expression of the alloy is (TiaZrbNbcAld) 100-eOe, wherein a is greater than or equal to 36at.% and less than or equal to 50at.%, b is greater than or equal to 36at.% and less than or equal to 49at.%, c is greater than or equal to 3at.% and less than or equal to 17at.%, d is greater than or equal to 1at.% and less than or equal to 7at.%, e is greater than or equal to 0.5 at.% and less than or equal to 2.0 at.%, and a + b + c + d is equal to 100at.%. The preparation method comprises the steps that all the raw materials are mixed and smelted to prepare a cast ingot, grinding and polishing are conducted after linear cutting, and the interstitial oxygen doped Ti-Zr-Nb-Al medium-entropy alloy with the superhard oxide layer is obtained. And then thermal oxidation is conducted for 6 h in the air atmosphere at the temperature of 500 DEG C, and after natural cooling is conducted to the room temperature, the interstitial oxygen doped Ti-Zr-Nb-Al medium-entropy alloy with the superhard oxide layer is obtained. The invention further provides application of the medical orthopedic implant material. The interstitial oxygen doped Ti-Zr-Nb-Al medium-entropy alloy with the superhard oxide layer prepared by the invention has lower elastic modulus, the surface of the oxidation-state alloy has ultrahigh hardness, the wear resistance is good, and the interstitial oxygen doped Ti-Zr-Nb-Al medium-entropy alloy can be used as a medical orthopedic implant material.

Description

Technical Field

[0001] The present invention belongs to the technical field of medium entropy alloys, and in particular relates to an interstitial oxygen-doped Ti-Zr-Nb-Al medium entropy alloy with a superhard oxide layer, and a preparation method and application thereof. Background Art

[0002] Metal materials were first used as orthopedic implant materials due to their high strength and toughness, fatigue resistance, easy processing and forming, and reliable clinical use, and are now widely used in clinical practice. Titanium alloys are well-known for their excellent specific strength, corrosion resistance and biocompatibility, and are preferred as the third-generation metal materials for bone implants. Among them, β-type titanium alloys (including full 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 developed rapidly. The main advantage of this alloy is that its elastic modulus is lower than that of other types of titanium alloys, which is conducive to reducing the stress shielding effect and promoting bone repair and reconstruction. Today, various countries have prepared a series of low-elastic β-titanium alloys such as Ti-Nb-(X), Ti-Mo-(X) and Ti-Ta-(X). However, low-elastic β-type medical titanium alloys represented by the Ti-Nb-(X) series still have the following bottleneck problems that hinder their application: ① The elastic modulus-yield strength of the alloy does not match, that is, the strength decreases severely with the decrease of the elastic modulus; 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-entropy and medium-entropy alloys (also known as multi-component solid solution alloys or multi-principal alloys) with three or more elements as the main components and coordinated performance control of each element have attracted extensive attention due to their excellent toughness, fatigue resistance, corrosion resistance and phase stability. As a rapidly developing new material, high-entropy and medium-entropy alloys are expected to be matched and applied in the biomedical field due to their significant advantages such as adjustable elastic modulus caused by complex interatomic forces, excellent strength caused by solid solution strengthening and orderly strengthening of oxygen interstitials, and deformation continuity brought by stable phase structure. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide an interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with a superhard oxide layer and a preparation method and application thereof in view of the deficiencies of the above-mentioned prior art. The alloy has a low elastic modulus, and the surface of the oxidized alloy has ultra-high hardness and good wear resistance, and can be used for medical orthopedic implant materials.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: an interstitial oxygen-doped Ti-Zr-Nb-Al medium entropy alloy with a superhard oxide layer, the expression of the interstitial oxygen-doped Ti-Zr-Nb-Al medium entropy alloy with a superhard oxide layer is: (Ti a Zr bNb c Al d ) 100-e O e , 36at.%≤a≤50at.%, 36at.%≤b≤49at.%, 3at.%≤c≤17at.%, 1at.%≤d≤7at.%, 0.5at.%≤e≤2.0at.%, a+b+c+d=100at.%.

[0006] The present invention also provides a method for preparing the interstitial oxygen-doped Ti-Zr-Nb-Al medium entropy alloy having a superhard oxide layer, the method comprising:

[0007] S1, industrial pure titanium TA1 particles, industrial pure zirconium Zr-1 particles, industrial pure niobium Nb1 particles, ZrO 2 The particles and pure Al particles are mixed and prepared into ingots by electric arc furnace melting or vacuum suspension melting;

[0008] The industrial pure titanium TA1 particles contain Ti≥99.5wt.%, the industrial pure zirconium Zr-1 particles contain Zr+Hf≥99.2wt.%, the industrial grade niobium Nb1 particles contain Nb≥99.9wt.%, and the ZrO 2 The purity of the particles is ≥99.9wt.%, and the purity of the Al particles is ≥99.0wt.%;

[0009] In the present invention, oxygen atoms can enter the lattice gap to form an ordered interstitial atomic complex, thereby enhancing the comprehensive performance of the alloy; the alloy is designed based on Ti-Zr-Nb as the basic alloy, with a small amount of Al added. In the Ti-Zr-Nb basic alloy, the content of Ti and Zr is relatively high, and 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 a stabilizing element of the BCC structure and is indispensable. Therefore, the above ratio is adopted; the atomic radius of Al is similar to that of Ti and Zr alloys, which can curb the generation of brittle intermediate phases, and the content of Al element is lower than the Al content in Ti6Al4V (the biomedical Ti alloy currently widely used in clinical practice), which is an acceptable tolerance for the human body;

[0010] S2. The ingot obtained in S1 is cut into rectangular blocks by wire cutting, and then ground with 400#, 800#, 1500#, 2000# and 3000# sandpaper in sequence, and finally polished, and then thermally oxidized for 6 hours in an air atmosphere at a temperature of 500°C to produce a superhard oxide film on its surface. After naturally cooling to room temperature, an interstitial oxygen-doped Ti-Zr-Nb-Al medium entropy alloy with a superhard oxide layer is obtained.

[0011] Preferably, the arc furnace smelting method in S1 is: pure Al particles, industrial pure titanium TA1 particles, ZrO 2 Particles, industrial pure zirconium Zr-1 particles, and industrial pure niobium Nb1 particles were placed in a copper crucible and the vacuum degree was drawn to 3.7×10 -3 Pa, high-purity argon gas is charged to 0.05MPa, the current during smelting is 450A-550A, single smelting is 3min, water cooling is 8min after single smelting, and smelting is continued after turning over, and smelting is performed 6-8 times in total, and the smelted alloy liquid is poured into a copper mold, cooled by water to obtain an ingot;

[0012] The vacuum suspension melting method comprises: sequentially mixing pure Al particles, industrial pure titanium TA1 particles, ZrO 2 Particles, industrial pure zirconium Zr-1 particles, and industrial pure niobium Nb1 particles were placed in a copper crucible and the vacuum degree was drawn to 3.7×10 -3 Pa, rush high-purity argon to 0.05MPa, increase the power at a rate of 0.5kW / min until all particles are completely melted, keep warm for 30min, and then reduce the power at a rate of 1.5kW / min until the alloy is cooled and formed to obtain an ingot.

[0013] Preferably, the yield strength of the ingot in S1 is 571MPa-820MPa, and the elastic modulus is 45GPa-69GPa; the hardness of the interstitial oxygen-doped Ti-Zr-Nb-Al medium entropy alloy with superhard oxide layer in S2 is 1010HV 0.2 ~1040HV 0.2 .

[0014] The alloy prepared by the present invention has a lower elastic modulus, higher strength and ultra-high hardness, and can be applied to biomedical materials.

[0015] The present invention also provides an application of an interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy having an ultra-hard oxide layer prepared by the above-mentioned preparation method, wherein the interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy having an ultra-hard oxide layer is used as a medical orthopedic implant material.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] The interstitial oxygen-doped Ti-Zr-Nb-Al medium entropy alloy with a superhard oxide layer prepared by the present invention has a low elastic modulus and moderate strength, and the oxidized alloy surface has ultra-high hardness, and can be used for medical orthopedic implant materials, such as bone plates, bone nails, bone needles, bone rods, etc. The alloy uses industrial raw materials instead of high-purity raw materials, which significantly reduces costs, and the alloy smelting method is simple and reliable. In addition, through simple oxidation heat treatment, a superhard oxide film can be formed on the alloy surface, and the wear resistance is increased. This feature can expand the application range of the alloy to the field of joints.

[0018] The present invention is further described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is the XRD spectrum of the interstitial oxygen-doped Ti-Zr-Nb-Al medium entropy alloy with superhard oxide layer prepared in Examples 1-3 of the present invention.

[0020] Figure 2 It is the XRD spectrum of the interstitial oxygen-doped Ti-Zr-Nb-Al medium entropy alloy with superhard oxide layer prepared in Example 4-7 of the present invention.

[0021] Figure 3 1 is the room temperature tensile stress-strain curve of the interstitial oxygen-doped Ti-Zr-Nb-Al medium entropy alloy with a superhard oxide layer prepared in Examples 1-3 of the present invention.

[0022] Figure 4 It is the room temperature tensile stress-strain curve of the interstitial oxygen-doped Ti-Zr-Nb-Al medium entropy alloy with superhard oxide layer prepared in Examples 4-7 of the present invention.

[0023] Figure 5 This is the XRD spectrum of the interstitial oxygen-doped Ti-Zr-Nb-Al medium entropy alloy with a superhard oxide layer prepared in Example 2-3 of the present invention during room temperature stretching.

[0024] Figure 6 It is an oxidation time-hardness curve at different temperatures (400° C., 450° C., 500° C.) during the preparation process of the medium-entropy alloy prepared in Example 1 of the present invention.

[0025] Figure 7 This is the wear depth curve of the 1&O# medium-entropy alloy (oxidized at 500°C for 6 hours) prepared in Example 1 of the present invention. The illustration in the middle is the wear depth curve of the 1# medium-entropy alloy. DETAILED DESCRIPTION

[0026] The raw materials used in the embodiments of the present invention are industrial pure titanium TA1 particles (Ti≥99.5wt.%), which are purchased from Baoji Zhongliyang Metal Co., Ltd.

[0027] Industrial pure zirconium Zr-1 particles (Zr+Hf≥99.2wt.%), purchased from Baoji Zhongliyang Metal Co., Ltd.;

[0028] Industrial grade niobium Nb1 particles (Nb≥99.9wt.%), purchased from Baoji Zhongliyang Metal Co., Ltd.;

[0029] ZrO 2 Particles (purity ≥ 99.9 wt.%), commercially available from Baoji Zhongliyang Metal Co., Ltd.;

[0030] Al particles (purity ≥ 99.9 wt.%), commercially available from Baoji Zhongliyang Metal Co., Ltd.;

[0031] The oxide scale of each raw material was removed and the raw materials were ultrasonically cleaned with industrial ethanol.

[0032] Example 1

[0033] The interstitial oxygen-doped Ti-Zr-Nb-Al medium entropy alloy with a superhard oxide layer in this embodiment is expressed as follows: (Ti a Zr b Nb c Al d ) 100-e O e , a=45at.%, ​​b=45at.%, ​​c=9at.%, ​​d=1at.%, ​​e=0.5at.%, ​​named (Ti 45 Zr 45 Nb 9 Al 1 ) 99.5 O 0.5 .

[0034] This embodiment also provides a method for preparing the interstitial oxygen-doped Ti-Zr-Nb-Al medium entropy alloy having a superhard oxide layer, which is:

[0035] S1, industrial pure titanium TA1 particles, industrial pure zirconium Zr-1 particles, industrial pure niobium Nb1 particles, ZrO 2 The particles and pure Al particles are mixed and smelted in an electric arc furnace to prepare an ingot;

[0036] The arc furnace smelting method is: pure Al particles, industrial pure titanium TA1 particles, ZrO 2 Particles, industrial pure zirconium Zr-1 particles, and industrial pure niobium Nb1 particles were placed in a copper crucible and the vacuum degree was drawn to 3.7×10 -3Pa, high-purity argon gas was charged to 0.05MPa, the current during smelting was 500A, single smelting was 3min, water cooling was performed for 8min after single smelting, and smelting was continued after turning over, and smelting was performed 6 times in total. The smelted alloy liquid was poured into a copper mold and cooled by water to obtain an ingot, which was recorded as 1# medium entropy alloy;

[0037] S2. The ingot obtained in S1 is cut into rectangular blocks by wire cutting, and then ground with 400#, 800#, 1500#, 2000# and 3000# sandpaper in sequence, and finally polished, and then thermally oxidized for 6 hours in an air atmosphere at a temperature of 500°C. After naturally cooling to room temperature, an interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with a super-hard oxide layer is obtained, which is recorded as 1&O# medium-entropy alloy.

[0038] The yield strength of the ingot (1# medium entropy alloy) before oxidation in this embodiment 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 a superhard oxide film prepared after oxidation is 1040 HV 0.2 .

[0039] Example 2

[0040] The interstitial oxygen-doped Ti-Zr-Nb-Al medium entropy alloy with a superhard oxide layer in this embodiment is expressed as follows: (Ti a Zr b Nb c Al d ) 100-e O e , a=45at.%, b=45at.%, c=5at.%, d=5at.%, e=0.5at.%, that is (Ti 45 Zr 45 Nb 5 Al 5 ) 99.5 O 0.5 .

[0041] This embodiment also provides a method for preparing the above-mentioned interstitial oxygen-doped Ti-Zr-Nb-Al medium entropy alloy having a superhard oxide layer, the method comprising:

[0042] S1, industrial pure titanium TA1 particles, industrial pure zirconium Zr-1 particles, industrial pure niobium Nb1 particles, ZrO 2 The particles and pure Al particles are mixed and smelted in an electric arc furnace to prepare an ingot;

[0043] The arc furnace smelting method is: pure Al particles, industrial pure titanium TA1 particles, ZrO 2Particles, industrial pure zirconium Zr-1 particles, and industrial pure niobium Nb1 particles were placed in a copper crucible and the vacuum degree was drawn to 3.7×10 -3 Pa, high-purity argon gas was charged to 0.05MPa, the current during smelting was 550A, single smelting was 3min, water cooling was performed for 8min after single smelting, smelting was continued after turning over, and smelting was performed 8 times in total. The smelted alloy liquid was poured into a copper mold and cooled by water to obtain an ingot, which was recorded as 2# medium entropy alloy;

[0044] S2. The ingot obtained in S1 is cut into rectangular blocks by wire cutting, and then ground with 400#, 800#, 1500#, 2000# and 3000# sandpaper in sequence, and finally polished, and then thermally oxidized for 6 hours in an air atmosphere at a temperature of 500°C. After naturally cooling to room temperature, an interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with a super-hard oxide layer is obtained, which is recorded as 2&O# medium-entropy alloy.

[0045] The yield strength of the ingot (2# medium entropy alloy) before oxidation in this embodiment 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 a superhard oxide film prepared after oxidation is 1020 HV 0.2 .

[0046] Example 3

[0047] The interstitial oxygen-doped Ti-Zr-Nb-Al medium entropy alloy with a superhard oxide layer in this embodiment is expressed as follows: (Ti a Zr b Nb c Al d ) 100-e O e , a=45at.%, b=45at.%, c=3at.%, d=7at.%, e=0.5at.%, that is (Ti 45 Zr 45 Nb 3 Al 7 ) 99.5 O 0.5 .

[0048] This embodiment also provides a method for preparing the above-mentioned interstitial oxygen-doped Ti-Zr-Nb-Al medium entropy alloy having a superhard oxide layer, the method comprising:

[0049] S1, industrial pure titanium TA1 particles, industrial pure zirconium Zr-1 particles, industrial pure niobium Nb1 particles, ZrO 2 The particles and pure Al particles are mixed and prepared into ingots by vacuum suspension melting;

[0050] The vacuum suspension melting method comprises: sequentially mixing pure Al particles, industrial pure titanium TA1 particles, ZrO 2 Particles, industrial pure zirconium Zr-1 particles, and industrial pure niobium Nb1 particles were placed in a copper crucible and the vacuum degree was drawn to 3.7×10 -3 Pa, high-purity argon gas was injected to 0.05MPa, the power was increased at a rate of 0.5kW / min until all particles were completely melted, and the temperature was kept for 30min, and then the power was decreased at a rate of 1.5kW / min until the alloy was cooled and formed to obtain an ingot, which was recorded as 3# medium entropy alloy;

[0051] S2. The ingot obtained in S1 is cut into rectangular blocks by wire cutting, and then ground with 400#, 800#, 1500#, 2000# and 3000# sandpaper in sequence, and finally polished, and then thermally oxidized for 6 hours in an air atmosphere at a temperature of 500°C. After naturally cooling to room temperature, an interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with a super-hard oxide layer is obtained, which is recorded as 3&O# medium-entropy alloy.

[0052] The yield strength of the ingot (3# medium entropy alloy) before oxidation in this embodiment 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 a superhard oxide film prepared after oxidation is 1010 HV 0.2 .

[0053] Example 4

[0054] The interstitial oxygen-doped Ti-Zr-Nb-Al medium entropy alloy with a superhard oxide layer in this embodiment is expressed as follows: (Ti a Zr b Nb c Al d ) 100-e O e , a=40at.%, b=40at.%, c=17at.%, d=3at.%, e=1at.%, that is (Ti 40 Zr 40 Nb 17 Al 3 ) 99 O 1 .

[0055] This embodiment also provides a method for preparing the interstitial oxygen-doped Ti-Zr-Nb-Al medium entropy alloy having a superhard oxide layer, which is:

[0056] S1, industrial pure titanium TA1 particles, industrial pure zirconium Zr-1 particles, industrial pure niobium Nb1 particles, ZrO2 The particles and pure Al particles are mixed and smelted in an electric arc furnace to prepare an ingot, which is recorded as 4# medium entropy alloy;

[0057] The arc furnace smelting method is: pure Al particles, industrial pure titanium TA1 particles, ZrO 2 Particles, industrial pure zirconium Zr-1 particles, and industrial pure niobium Nb1 particles were placed in a copper crucible and the vacuum degree was drawn to 3.7×10 -3 Pa, high-purity argon gas is charged to 0.05MPa, the current during smelting is 500A, single smelting is 3min, water cooling is performed for 8min after single smelting, and smelting is continued after turning over, and smelting is performed 7 times in total, and the smelted alloy liquid is poured into a copper mold, cooled by water to obtain an ingot;

[0058] S2. The ingot obtained in S1 is cut into rectangular blocks by wire cutting, and then ground with 400#, 800#, 1500#, 2000# and 3000# sandpaper in sequence, and finally polished, and then thermally oxidized for 6 hours in an air atmosphere at a temperature of 500°C. After naturally cooling to room temperature, an interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with a super-hard oxide layer is obtained, which is recorded as 4&O# medium-entropy alloy.

[0059] The yield strength of the ingot (4# medium entropy alloy) before oxidation in this embodiment 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 a superhard oxide film prepared after oxidation is 1010 HV 0.2 .

[0060] Example 5

[0061] The interstitial oxygen-doped Ti-Zr-Nb-Al medium entropy alloy with a superhard oxide layer in this embodiment is expressed as follows: (Ti a Zr b Nb c Al d ) 100-e O e , a=50at.%, b=40at.%, c=7at.%, d=3at.%, e=1at.%, that is (Ti 50 Zr 40 Nb 7 Al 3 ) 99 O 1 .

[0062] This embodiment also provides a method for preparing the interstitial oxygen-doped Ti-Zr-Nb-Al medium entropy alloy having a superhard oxide layer, which is:

[0063] S1, industrial pure titanium TA1 particles, industrial pure zirconium Zr-1 particles, industrial pure niobium Nb1 particles, ZrO 2 The particles and pure Al particles are mixed and smelted in an electric arc furnace to prepare an ingot, which is recorded as 5# medium entropy alloy;

[0064] The arc furnace smelting method is: pure Al particles, industrial pure titanium TA1 particles, ZrO 2 Particles, industrial pure zirconium Zr-1 particles, and industrial pure niobium Nb1 particles were placed in a copper crucible and the vacuum degree was drawn to 3.7×10 -3 Pa, high-purity argon gas is charged to 0.05MPa, the current during smelting is 550A, single smelting is 3min, water cooling is 8min after single smelting, and smelting is continued after turning over, and smelting is performed 6 times in total, and the smelted alloy liquid is poured into a copper mold and cooled by water to obtain an ingot;

[0065] S2. The ingot obtained in S1 is cut into rectangular blocks by wire cutting, and then ground with 400#, 800#, 1500#, 2000# and 3000# sandpaper in sequence, and finally polished, and then thermally oxidized for 6 hours in an air atmosphere at a temperature of 500°C. After naturally cooling to room temperature, an interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with a super-hard oxide layer is obtained, which is recorded as 5&O# medium-entropy alloy.

[0066] The yield strength of the ingot (5# medium entropy alloy) before oxidation in this embodiment 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 a superhard oxide film prepared after oxidation is 1030 HV 0.2 .

[0067] Example 6

[0068] The interstitial oxygen-doped Ti-Zr-Nb-Al medium entropy alloy with a superhard oxide layer in this embodiment is expressed as follows: (Ti a Zr b Nb c Al d ) 100-e O e , a=50at.%, b=36at.%, c=10at.%, d=4at.%, e=2at.%, that is (Ti 50 Zr 36 Nb 10 Al 4 ) 98 O 2 .

[0069] This embodiment also provides a method for preparing the above-mentioned interstitial oxygen-doped Ti-Zr-Nb-Al medium entropy alloy having a superhard oxide layer, the method comprising:

[0070] S1, industrial pure titanium TA1 particles, industrial pure zirconium Zr-1 particles, industrial pure niobium Nb1 particles, ZrO 2 The particles and pure Al particles are mixed and smelted in an electric arc furnace to prepare an ingot, which is recorded as 6# medium entropy alloy;

[0071] The arc furnace smelting method is: pure Al particles, industrial pure titanium TA1 particles, ZrO 2 Particles, industrial pure zirconium Zr-1 particles, and industrial pure niobium Nb1 particles were placed in a copper crucible and the vacuum degree was drawn to 3.7×10 -3 Pa, high-purity argon gas is charged to 0.05MPa, the current during smelting is 450A, single smelting is 3min, water cooling is performed for 8min after single smelting, and smelting is continued after turning over, and smelting is performed 6 times in total, the smelted alloy liquid is poured into a copper mold, and water-cooled to obtain an ingot;

[0072] S2. The ingot obtained in S1 is cut into rectangular blocks by wire cutting, and then ground with 400#, 800#, 1500#, 2000# and 3000# sandpaper in sequence, and finally polished, and then thermally oxidized for 6 hours in an air atmosphere at a temperature of 500°C. After naturally cooling to room temperature, an interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with a super-hard oxide layer is obtained, which is recorded as 6&O# medium-entropy alloy.

[0073] The yield strength of the ingot (6# medium entropy alloy) before oxidation in this embodiment 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 a superhard oxide film prepared after oxidation is 1035 HV 0.2 .

[0074] Example 7

[0075] The interstitial oxygen-doped Ti-Zr-Nb-Al medium entropy alloy with a superhard oxide layer in this embodiment is expressed as follows: (Ti a Zr b Nb c Al d ) 100-e O e , a=36at.%, b=49at.%, c=17at.%, d=3at.%, e=0.5at.%, that is (Ti 36 Zr 49 Nb 17 Al 3 )99.5 O 0.5 .

[0076] This embodiment also provides a method for preparing the above-mentioned interstitial oxygen-doped Ti-Zr-Nb-Al medium entropy alloy having a superhard oxide layer, the method comprising:

[0077] S1, industrial pure titanium TA1 particles, industrial pure zirconium Zr-1 particles, industrial pure niobium Nb1 particles, ZrO 2 The particles and pure Al particles are mixed and smelted in an electric arc furnace to prepare an ingot, which is recorded as 7# medium entropy alloy;

[0078] The arc furnace smelting method is: pure Al particles, industrial pure titanium TA1 particles, ZrO 2 Particles, industrial pure zirconium Zr-1 particles, and industrial pure niobium Nb1 particles were placed in a copper crucible and the vacuum degree was drawn to 3.7×10 -3 Pa, high-purity argon gas is charged to 0.05MPa, the current during smelting is 480A, single smelting is 3min, water cooling is performed for 8min after single smelting, and smelting is continued after turning over, and smelting is performed 7 times in total, and the smelted alloy liquid is poured into a copper mold, cooled by water to obtain an ingot;

[0079] S2. The ingot obtained in S1 is cut into rectangular blocks by wire cutting, and then ground with 400#, 800#, 1500#, 2000# and 3000# sandpaper in sequence, and finally polished, and then thermally oxidized for 6 hours in an air atmosphere at a temperature of 500°C. After naturally cooling to room temperature, an interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with a super-hard oxide layer is obtained, which is recorded as 7&O# medium-entropy alloy.

[0080] The yield strength of the ingot (7# medium entropy alloy) before oxidation in this embodiment 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 a superhard oxide film prepared after oxidation is 1015 HV 0.2 .

[0081] Example 8

[0082] This example is a test of the organizational structure and performance of the interstitial oxygen-doped Ti-Zr-Nb-Al medium entropy alloys (1# to 7# medium entropy alloys) with a super-hard oxide layer prepared in Examples 1-7. The interstitial oxygen-doped Ti-Zr-Nb-Al medium entropy alloys with a super-hard oxide layer of the present invention are used for medical orthopedic implant materials.

[0083] (1) Phase structure of alloy

[0084] The X-ray diffractometer was used to perform phase analysis on the medium entropy alloy with a scanning step size of 0.02 and a scanning rate of 5° / min.

[0085] The XRD patterns of the 1#, 2# and 3# medium entropy alloys prepared in Examples 1-3 of the present invention are as follows: Figure 1 As shown, the XRD patterns of the 4#, 5#, 6# and 7# medium entropy alloys prepared in Examples 4-7 are as follows Figure 2 As shown in the figure, the 1# medium entropy alloy is a β structure, the 2# and 3# medium entropy alloys contain a large amount of β structure and a small amount of orthorhombic martensitic α" structure, and the 4#, 5#, 6# and 7# medium entropy alloys are β structures.

[0086] (2) Room temperature tensile properties and phase transition

[0087] The interstitial oxygen-doped Ti-Zr-Nb-Al medium entropy alloy with superhard oxide layer prepared in each embodiment was cut into plate-shaped proportional (proportional coefficient k = 5.65) tensile specimens and tested on a universal mechanical testing machine equipped with a video extensometer at a speed of 0.001s -1 The engineering stress-strain curves of 1#, 2# and 3# alloys were tensile at room temperature at a strain rate of Figure 3 The engineering stress-strain curves of 4#, 5#, 6# and 7# alloys are shown in Figure 4 shown.

[0088] The true stress-strain curves of all alloys show that no obvious yield platform is observed during the tensile process. 0.2 The yield strengths of alloys 1#, 2#, 3#, 4#, 5#, 6# and 7# are 685MPa, 660MPa, 571MPa, 650MPa, 703MPa, 820MPa and 610MPa, respectively, and the elastic moduli are 54GPa, 69GPa, 45GPa, 67GPa, 56GPa, 68GPa and 64GPa. The elastic moduli of all alloys are lower than that of Ti6Al4V alloy (~110GPa), and they maintain a high tensile strength, which helps to solve the mismatch problem between alloys and human bones, namely "stress shielding".

[0089] During the stretching process, the 1#, 4#, 5#, 6# and 7# medium entropy alloys did not undergo phase transformation during room temperature stretching, and only the 2# and 3# medium entropy alloys underwent phase transformation. Their XRD patterns during the stretching process are shown in Figure 2. Figure 5 shown.

[0090] XRD spectra show that phase transformation occurred in 2# and 3# medium entropy alloys during the stretching process, and the alloy structure changed from a composite structure of a large amount of β and a small amount of α" to a composite structure of a large amount of α' / α and a small amount of α".

[0091] The difference in yield and elastic modulus before and after oxidation in each embodiment (the ingot prepared in step S1 and the interstitial oxygen-doped Ti-Zr-Nb-Al medium entropy alloy with a superhard oxide layer obtained after oxidation in step S2) is negligible. During the thermal oxidation process of the alloy matrix at 500°C / 6h, the alloy structure is almost unchanged. At the same time, the oxide layer on the surface of the alloy is relatively thin, about 13μm, so at this temperature, the yield and elastic modulus of the alloy are almost unaffected.

[0092] 3) Properties of oxidized alloys

[0093] A. Hardness

[0094] While preparing the 1# medium entropy alloy in Example 1, the oxidation temperature and time in step S2 of the preparation method in Example 1 were optimized. That is, on the basis of oxidation at 500°C for 6h in step S2, optimization tests were performed at temperatures of 400°C, 450°C and 500°C, and oxidation times of 3h and 6h. The surface hardness of the prepared medium entropy alloy was plotted as a function of oxidation and time. Figure 6 Among them, the 1&O# medium entropy alloy oxidized at 500℃ exhibited ultra-high hardness, with the hardness increasing from 267HV 0.2 (0h, before oxidation) increased to 1040HV 0.2 (6h). In addition, after oxidation at 500℃ for 6 hours, the hardness of Examples 2-7 exceeded 1000HV. 0.2 .

[0095] B. Wear resistance

[0096] The 1# medium entropy alloy prepared after oxidation at 500℃ for 6 hours in Example 1 was used for friction and wear experiments. The friction and wear test of this experiment was carried out on a UMT-Tribolab series friction and wear machine. When the sample was rubbed, the sliding frequency was 1HZ, the load was 3N, the friction was 30min, and the grinding material was a silicon nitride ball. The wear depth curve of the 1# medium entropy alloy prepared after oxidation at 500℃ for 6 hours is shown in Figure 1. Figure 7 As shown, the upper middle illustration is the wear depth curve of the 1# medium entropy alloy (i.e., the ingot prepared in step S1) before oxidation.

[0097] The wear depth of the 1&O# medium entropy alloy after oxidation is significantly reduced compared with that before oxidation, and the wear depth of the 1&O# medium entropy alloy after oxidation is smaller than that of Ti6Al4V (TC4) after oxidation at 500℃ for 6 hours.

[0098] The present invention has newly designed a Ti-Zr-Nb-Al medium entropy alloy, and on this basis, has innovatively added interstitial element oxygen, and the alloy exhibits higher tensile strength and lower elastic modulus. Compared with the existing medical Ti6Al4V alloy and β-titanium alloy, the alloy has higher strength and lower elastic modulus, and can cover a wider range of orthopedic implants (bone plates, bone nails, bone needles, bone rods). Compared with other medical high and medium entropy alloys, the alloy uses industrial raw materials instead of high-purity raw materials, which significantly reduces costs, and the alloy smelting method is simple and reliable. In addition, through simple oxidation heat treatment, a superhard oxide film can be formed on the surface of the alloy, and the wear resistance is increased. This feature can expand the application range of the alloy to the field of joints.

[0099] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent change made to the above embodiment according to the technical essence of the invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. An interstitial oxygen-doped Ti-Zr-Nb-Al medium entropy alloy having a superhard oxide layer, characterized in that: The expression of the interstitial oxygen-doped Ti-Zr-Nb-Al medium entropy alloy with superhard oxide layer is: a Zr b Nb c Al d ) 100-e O e , 36at.%≤a≤50at.%, 36at.%≤b≤49at.%, 3at.%≤c≤17at.%, 1at.%≤d≤7at.%, 0.5at.%≤e≤2.0at.%, a+b+c+d=100at.%.

2. A method for preparing the interstitial oxygen-doped Ti-Zr-Nb-Al medium entropy alloy having a superhard oxide layer as claimed in claim 1, characterized in that: The method is: S1, industrial pure titanium TA1 particles, industrial pure zirconium Zr-1 particles, industrial pure niobium Nb1 particles, ZrO2 particles, and pure Al particles are mixed, and an ingot is prepared by electric arc furnace melting or vacuum suspension melting; The industrial pure titanium TA1 particles contain Ti≥99.5wt.%, the industrial pure zirconium Zr-1 particles contain Zr+Hf≥99.2wt.%, the industrial grade niobium Nb1 particles contain Nb≥99.9wt.%, the purity of the ZrO2 particles is ≥99.9wt.%, and the purity of the Al particles is ≥99.0wt.%; S2. The ingot obtained in S1 is cut into rectangular blocks by wire cutting, and then ground with 400#, 800#, 1500#, 2000# and 3000# sandpaper in sequence, and finally polished, and then thermally oxidized for 6 hours in an air atmosphere at a temperature of 500°C. After naturally cooling to room temperature, an interstitial oxygen-doped Ti-Zr-Nb-Al medium-entropy alloy with a super-hard oxide layer is obtained.

3. The method according to claim 2, characterized in that The arc furnace smelting method described in S1 is: pure Al particles, industrial pure titanium TA1 particles, ZrO2 particles, industrial pure zirconium Zr-1 particles, and industrial pure niobium Nb1 particles are placed in a copper crucible in sequence, and the vacuum degree is drawn to 3.7×10 -3 Pa, high-purity argon gas is charged to 0.05MPa, the current during smelting is 450A-550A, single smelting is 3min, water cooling is 8min after single smelting, and smelting is continued after turning over, and smelting is performed 6-8 times in total, and the smelted alloy liquid is poured into a copper mold, cooled by water to obtain an ingot; The vacuum suspension smelting method comprises: placing pure Al particles, industrial pure titanium TA1 particles, ZrO2 particles, industrial pure zirconium Zr-1 particles, and industrial pure niobium Nb1 particles into a copper crucible in sequence, and drawing the vacuum degree to 3.7×10 -3 Pa, rush high-purity argon to 0.05MPa, increase the power at a rate of 0.5kW / min until all particles are completely melted, keep warm for 30min, and then reduce the power at a rate of 1.5kW / min until the alloy is cooled and formed to obtain an ingot.

4. The method according to claim 2, characterized in that: The yield strength of the ingot in S1 is 571MPa-820MPa, and the elastic modulus is 45GPa-69GPa; the hardness of the interstitial oxygen-doped Ti-Zr-Nb-Al medium entropy alloy with a superhard oxide layer in S2 is 1010HV 0.2 ~1040HV 0.2 .

5. An application of an interstitial oxygen-doped Ti-Zr-Nb-Al medium entropy alloy having a superhard oxide layer prepared by the preparation method according to any one of claims 2 to 4, characterized in that: The interstitial oxygen-doped Ti-Zr-Nb-Al medium entropy alloy with a superhard oxide layer is used for medical orthopedic implant materials.

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