A low modulus metastable β titanium alloy and its preparation method and metal implant

Abstract

The present invention provides a low modulus metastable β titanium alloy and a preparation method thereof and a metal implant, belonging to the technical field of alloy materials. The low modulus metastable β titanium alloy provided by the present invention comprises Nb20-30wt%, Zr0.1-9wt%, Sn0.1-8wt%, Mo0.1-5wt%, Ta0.1-5wt%, and the balance is Ti. In the present invention, by strictly controlling the content of each element and reducing the stability of the β phase, the titanium alloy has a lower elastic modulus, has good matching with the elastic modulus of human bones, can effectively avoid the stress shielding effect, and the metal implant prepared by using the titanium alloy has good mechanical compatibility.

Description

Technical Field

[0001] The invention relates to the technical field of alloy materials, and in particular to a low modulus metastable β titanium alloy and a preparation method thereof and a metal implant. Background Art

[0002] Biometal materials refer to metal materials that can be implanted into the human body (or animal body) to repair organs and restore functions. Metal biomaterials are widely used as implant materials for hard tissues such as bones due to their good comprehensive properties, such as high strength and fatigue resistance, and easy processing and molding.

[0003] Currently, commonly used metal implant materials include stainless steel, cobalt-based alloys and Ti-6Al-4V alloys, but a common problem faced by using these metal implant materials is that their elastic modulus does not match the elastic modulus of human bones. For example, the elastic modulus of stainless steel is 200-210GPa, the elastic modulus of cobalt-based alloys is 210-253GPa, and the elastic modulus of Ti-6Al-4V alloy is 110GPa, while the elastic modulus of human bones is only 10-30GPa. Obviously, the elastic modulus of the above metal implant materials is significantly greater than that of human bones, which will lead to stress shielding effect and damage the mechanical compatibility of implants. Summary of the invention

[0004] The purpose of the present invention is to provide a low modulus metastable β titanium alloy and a preparation method thereof and a metal implant. The titanium alloy provided by the present invention has a low elastic modulus, has a good match with the elastic modulus of human bones, can effectively avoid the stress shielding effect, and the metal implant prepared using the titanium alloy has good mechanical compatibility.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The invention provides a low modulus metastable beta titanium alloy, which comprises 20-30wt% of Nb, 0.1-9wt% of Zr, 0.1-8wt% of Sn, 0.1-5wt% of Mo, 0.1-5wt% of Ta and the balance of Ti.

[0007] Preferably, it comprises 23-28wt% Nb, 2-6wt% Zr, 3-7wt% Sn, 0.3-2wt% Mo, 0.5-3wt% Ta, and the balance is Ti.

[0008] Preferably, it comprises 25-26wt% Nb, 3-4wt% Zr, 4-5wt% Sn, 0.5-1wt% Mo, 1-2wt% Ta, and the balance is Ti.

[0009] Preferably, the main phase of the low modulus metastable β titanium alloy is β phase.

[0010] The present invention provides a method for preparing the low modulus metastable β titanium alloy described in the above technical solution, comprising the following steps:

[0011] According to the elemental composition of the low modulus metastable β titanium alloy described in the above technical solution, the raw materials are mixed and then smelted, and then cooled to obtain an ingot;

[0012] The ingot is sequentially hot rolled, solid-solutionized, water quenched and cold rolled to obtain a low modulus metastable β titanium alloy.

[0013] Preferably, the smelting temperature is 3200-3500° C., the smelting is repeated 3-4 times, and the time for a single smelting is 10-15 minutes.

[0014] Preferably, the hot rolling temperature is 850-950° C., and the total deformation amount of the hot rolling in the thickness direction is 60-80%.

[0015] Preferably, the solution temperature is 950-1050° C., and the holding time is 20-30 min.

[0016] Preferably, the cold rolling is a multi-pass cold rolling, and the total deformation of the cold rolling in the thickness direction is 0 to 90%.

[0017] The present invention provides a metal implant, which is prepared from the low modulus metastable β titanium alloy described in the above technical solution or the low modulus metastable β titanium alloy prepared by the preparation method described in the above technical solution.

[0018] The present invention provides a low modulus metastable β titanium alloy, comprising 20-30wt% Nb, 0.1-9wt% Zr, 0.1-8wt% Sn, 0.1-5wt% Mo, 0.1-5wt% Ta, and the balance being Ti. In the present invention, by strictly controlling the content of each element and reducing the stability of the β phase, the titanium alloy has a lower elastic modulus, has good matching with the elastic modulus of human bones, can effectively avoid stress shielding effect, and can meet the needs of human bone implants. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 XRD pattern of the titanium alloy prepared in Example 1;

[0020] Figure 2 A schematic diagram of a tensile sample required for a tensile test of the titanium alloy prepared in the embodiment;

[0021] Figure 3 The true stress-strain curve obtained by tensile testing the titanium alloy prepared in Example 1;

[0022] Figure 4XRD diagram of the titanium alloys prepared in Example 2 and Example 3;

[0023] Figure 5 True stress-strain curves obtained by tensile testing the titanium alloys prepared in Example 2 and Example 3;

[0024] Figure 6 for Figure 5 Zoomed-in view of the elastic phase of the true stress-strain curve. DETAILED DESCRIPTION

[0025] The invention provides a low modulus metastable beta titanium alloy, which comprises 20-30wt% of Nb, 0.1-9wt% of Zr, 0.1-8wt% of Sn, 0.1-5wt% of Mo, 0.1-5wt% of Ta and the balance of Ti.

[0026] The low modulus metastable β titanium alloy provided by the present invention comprises 20-30wt% Nb, preferably 23-28wt%, more preferably 25-26wt%, and further preferably 25.2-25.3wt%. In the present invention, the Nb is used as a β phase stabilizing element to regulate the β phase stability.

[0027] The low modulus metastable β titanium alloy provided by the present invention comprises Zr 0.1-9wt%, preferably 2-6wt%, more preferably 3-4wt%, and further preferably 3.9-4.0wt%. In the present invention, Zr acts as a weak β phase stabilizing element, and regulates the β phase stability under the interaction with other β phase stabilizing elements.

[0028] The low modulus metastable β titanium alloy provided by the present invention comprises 0.1-8wt% Sn, preferably 3-7wt% Sn, more preferably 4-5wt%, and further preferably 4.3-4.4wt%. In the present invention, the Sn is used as a weak β-phase stabilizing element to regulate the β-phase stability under the interaction with other β-phase stabilizing elements; at the same time, the low modulus of the Sn metal itself can effectively reduce the overall alloy modulus.

[0029] The low modulus metastable β titanium alloy provided by the present invention comprises 0.1-5wt% Mo, preferably 0.3-2wt%, more preferably 0.5-1wt%, and further preferably 0.8-0.9wt%. In the present invention, the Mo is used as a strong β phase stabilizing element to regulate the β phase stability.

[0030] The low modulus metastable β titanium alloy provided by the present invention comprises Ta 0.1-5wt%, preferably 0.5-3wt%, more preferably 1-2wt%, and further preferably 1.3-1.4wt%. In the present invention, the Ta is used as a β phase stabilizing element to regulate the β phase stability.

[0031] The low modulus metastable β titanium alloy provided by the present invention comprises a balance of Ti.

[0032] In the present invention, the main phase of the low modulus metastable β titanium alloy is β phase.

[0033] The present invention provides a preparation method of the low modulus metastable β titanium alloy described in the above technical solution, comprising the following steps:

[0034] According to the element composition of the low modulus metastable β titanium alloy described in the above technology, the raw materials are mixed and then smelted, and then cooled to obtain an ingot;

[0035] The ingot is sequentially hot rolled, solid-solutionized, water quenched and cold rolled to obtain a low modulus metastable β titanium alloy.

[0036] According to the elemental composition of the low modulus metastable β titanium alloy described in the above technology, the raw materials are mixed and then smelted, and an ingot is obtained by cooling. In the present invention, the raw materials for preparing the low modulus metastable β titanium alloy are preferably metal Ti, metal Nb, metal Zr, metal Mo, metal Ta and Ti-Sn master alloy; the purity of the metal Ti, metal Nb, metal Zr, metal Mo and metal Ta is preferably ≥99.99wt%; the Ti content in the Ti-Sn master alloy is preferably 20wt%.

[0037] After the raw materials are batched, the present invention melts the mixed raw materials obtained after batching, and the obtained molten liquid is cooled to obtain an ingot. In the present invention, the smelting temperature is preferably 3300-3500°C, more preferably 3500°C; the number of smelting is 3-4 times, more preferably 3 times; the time of a single smelting is preferably 10-15min, more preferably 15min; the smelting is preferably carried out in a protective atmosphere, and the present invention does not specifically limit the type of protective gas for providing the protective atmosphere, and a protective gas familiar to those skilled in the art can be used, such as argon. In the present invention, the smelting is preferably vacuum non-consumable arc melting. The present invention does not specifically limit the specific operation mode of the cooling, and a method familiar to those skilled in the art can be used. In an embodiment of the present invention, the ingot is specifically a semicircular shape with a diameter of 120mm and a height of 45mm.

[0038] After obtaining the ingot, the present invention sequentially hot-rolls, solid-solutionizes, water-quenches and cold-rolls the ingot to obtain a low modulus metastable β titanium alloy. In the present invention, the temperature of the hot rolling is preferably 850-950°C, more preferably 880-920°C, and further preferably 900°C; the total deformation of the hot rolling in the thickness direction is preferably 60-80%, more preferably 70-78%, and further preferably 77.8%. The present invention preferably performs hot rolling under the above conditions, so as to obtain a small thickness of the regular alloy and reduce the required rolling mill tonnage in the subsequent cold rolling process.

[0039] In the present invention, the solution temperature is preferably 950-1050°C, more preferably 980-1020°C, and further preferably 1000°C; the holding time is preferably 20-30 minutes, and more preferably 20 minutes. The present invention preferably performs solution treatment under the above conditions, and can eliminate the second phase that may be generated in the hot rolling process through short-time solution treatment.

[0040] The present invention has no special limitation on the water quenching, and a water quenching method well known to those skilled in the art can be used. The present invention preferably obtains a structure dominated by the β phase at room temperature by water quenching.

[0041] After the water quenching, the present invention preferably performs surface grinding on the obtained alloy and then performs cold rolling. The present invention does not specifically limit the surface grinding, and the surface grinding can be performed by methods well known to those skilled in the art. In the present invention, the cold rolling is preferably multi-pass cold rolling, and the number of the multi-pass cold rolling is preferably 4 to 6 times, and more preferably 5 times; there is preferably no intermediate annealing between adjacent cold rolling passes; the total deformation of the cold rolling in the thickness direction is preferably 0 to 90%, more preferably 0 to 70%, further preferably 25 to 35%, and further preferably 30%. The present invention preferably performs cold rolling under the above conditions, which can further reduce the stability of the β phase while increasing the dislocation density, and the elastic modulus obtained is lower than 30GPa, and the yield strength and tensile strength are significantly improved, which meets the needs of human bone implants.

[0042] The present invention provides a metal implant, which is prepared from the low modulus metastable β titanium alloy described in the above technical solution or the low modulus metastable β titanium alloy prepared by the preparation method described in the above technical solution. In the present invention, the metal implant is preferably a human bone implant.

[0043] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] Example 1

[0045] Metal Ti, metal Nb, metal Zr, metal Mo, metal Ta and Ti-Sn master alloy are mixed to obtain a mixed raw material; the purity of the metal Ti, metal Nb, metal Zr, metal Mo and metal Ta is 99.99wt%, and the Ti content in the Ti-Sn master alloy is 20wt%;

[0046] In an argon protective atmosphere, the mixed raw material is subjected to vacuum non-consumable arc melting for 3 times, wherein the melting temperature is 3500° C. and the single melting time is 15 minutes; the molten liquid obtained after the melting is cooled to obtain a semicircular ingot with a diameter of 120 mm and a height of 45 mm;

[0047] The ingot is hot rolled at 900° C. to obtain a hot rolled plate with a thickness of 10 mm and a deformation amount in the thickness direction of 77.8%;

[0048] Solvent-treating the hot-rolled plate at 1000° C. for 20 minutes to obtain a solution-treated plate;

[0049] The solid solution plate is sequentially subjected to water quenching, surface grinding and multiple cold rolling, wherein the number of cold rolling passes is 5 and there is no intermediate annealing between adjacent cold rolling passes, to obtain a low modulus metastable β titanium alloy with a thickness of 7 mm and a deformation in the thickness direction of 30%.

[0050] The titanium alloy prepared in this example was subjected to energy spectrum analysis under an Ultim Max 40 (MIRA4 LMH) scanning electron microscope, and its chemical composition is specifically shown in Table 1.

[0051] Table 1 Chemical composition of titanium alloy in Example 1 (mass percentage)

[0052] chemical composition Ti Nb Zr Mo Sn Ta name 64 26 4 1 4 1 Measured 64.12 25.28 3.99 0.87 4.36 1.38

[0053] The titanium alloy prepared in this example was characterized and its performance tested as follows:

[0054] 1. Use an electric spark cutting machine to cut a sample with a measuring instrument size of 10mm (length) × 10mm (width) × 7mm (thickness) from a large block of titanium alloy. The sample surface is polished for XRD analysis. The equipment used is a D / max2550 X-ray diffractometer. The experiment uses Cu radiation, graphite monochromator filtering, working voltage of 40kV, current of 450mA, scanning using step scanning, scanning rate of 5° / min, and scanning range of 10-80°. The results are as follows Figure 1 As shown, XRD analysis shows that only a single β phase exists.

[0055] 2. Use an EDM cutting machine to cut a tensile sample with a measuring instrument size of 30 mm (length) × 4 mm (width) × 1.5 mm (thickness) from a large block of titanium alloy (such as Figure 2As shown in Figure 1), the tensile performance test was carried out according to the standard of GB4338-1995 for high temperature tensile test of metal materials. In order to obtain accurate strain, an extensometer was used. The equipment was INSTRON 3369 electronic universal material testing machine. Three groups of tests were performed for each test and the average value was taken. The tensile rate was 2.0 mm / min. The obtained true stress-strain curve is shown in Figure 11. Figure 3 As shown, the front end linear part is fitted, and the elastic modulus of the titanium alloy is measured to be 27.47±1.69GPa, the nominal yield strength is 512.57±38.56MPa, the tensile strength is 612.30±32.06MPa, and the elongation is 12.27±0.75%.

[0056] Example 2

[0057] A titanium alloy was prepared according to the method of Example 1, except that the cold rolling deformation was 0.

[0058] Example 3

[0059] The titanium alloy was prepared according to the method of Example 1, except that the cold rolling deformation was 70%.

[0060] Figure 4 The XRD diagrams of the titanium alloys prepared in Examples 2 and 3 show that the titanium alloys prepared in Examples 2 and 3 still only have a single β phase, but their dislocation density increases with the increase in deformation. Through dislocation strengthening, the yield strength and tensile strength of the alloy are significantly improved.

[0061] The titanium alloys prepared in Example 2 and Example 3 were subjected to tensile tests. Three groups of tests were performed for each test and the average value was taken. The true stress-strain curves obtained are shown in FIG. Figure 5 As shown (for the convenience of comparison, the true stress-strain curve of the titanium alloy prepared in Example 1 obtained by tensile testing is also shown in Figure 5 (in Chinese). Figure 5 It can be seen that the elastic modulus of the titanium alloy prepared in Example 2 is 48.89±2.49GPa, the nominal yield strength is 247.71±15.01MPa, the tensile strength is 689.17±18.42MPa, and the elongation is 34.30±2.16%; the elastic modulus of the titanium alloy prepared in Example 3 is 42.52±3.49GPa, the nominal yield strength is 783.53±38.63MPa, the tensile strength is 875.99±42.56MPa, and the elongation is 7.52±1.5%. Figure 5 In the elastic stage of the true stress-strain curve, the results are as follows Figure 6As shown, it can be found that the titanium alloys prepared in Examples 1 to 3 of the present invention all have a low elastic modulus, which can meet the needs of human bone implants; especially the 30% cold rolling deformation in Example 1 can more effectively reduce the elastic modulus of the titanium alloy, and the comprehensive performance is excellent, which can effectively meet the needs of human bone implants.

[0062] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A low modulus metastable β titanium alloy comprising 25-26wt% Nb, 3-4wt% Zr, 4-5wt% Sn, 0.5-1wt% Mo, 1-2wt% Ta, and the balance being Ti; The method for preparing the low modulus metastable β titanium alloy comprises the following steps: According to the element composition of the low modulus metastable β titanium alloy, raw materials are mixed and then smelted, and then cooled to obtain an ingot; The ingot is sequentially hot-rolled, solid-solutionized, water-quenched and cold-rolled to obtain a low modulus metastable β titanium alloy; the total deformation amount of the cold rolling in the thickness direction is 30%; The hot rolling temperature is 850-900°C, and the total deformation in the thickness direction of the hot rolling is 70-78%; the solution temperature is 950-1050°C, and the holding time is 20-30 minutes; The elastic modulus of the low modulus metastable β titanium alloy is lower than 30 GPa.

2. The low modulus metastable β titanium alloy according to claim 1, characterized in that: The main phase of the low modulus metastable β titanium alloy is β phase.

3. The method for preparing the low modulus metastable β titanium alloy according to any one of claims 1 to 2, comprising the following steps: According to the elemental composition of the low modulus metastable β titanium alloy according to any one of claims 1 to 2, the raw materials are mixed and then smelted, and then cooled to obtain an ingot; The ingot is sequentially hot rolled, solid solution, water quenched and cold rolled to obtain a low modulus metastable β titanium alloy; the total deformation of the cold rolling in the thickness direction is 30%; the temperature of the hot rolling is 850-900°C, and the total deformation of the hot rolling in the thickness direction is 70-78%; the temperature of the solid solution is 950-1050°C, and the holding time is 20-30 minutes.

4. The preparation method according to claim 3, characterized in that: The smelting temperature is 3200-3500° C., the smelting times are 3-4 times, and the time of a single smelting is 10-15 minutes.

5. The preparation method according to claim 3, characterized in that: The cold rolling is a multi-pass cold rolling.

6. A metal implant prepared from the low modulus metastable β titanium alloy according to any one of claims 1 to 2 or the low modulus metastable β titanium alloy prepared by the preparation method according to any one of claims 3 to 5.

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