High-performance α+β+α′ three-phase Ti-13Nb-13Zr alloy and its preparation method

Abstract

The present invention belongs to the field of alloy materials, and particularly relates to a high-performance α+β+α′ three-phase Ti-13Nb-13Zr alloy and a preparation method thereof. Aging treatment is used to regulate the microstructure of the ultrafine-grained Ti-13Nb-13Zr alloy after continuous equal-channel angular pressing and rotary forging, and a Ti-13Nb-13Zr alloy containing α+β+α′ three phases is prepared. After the material is processed by Conform-ECAP+RS, the grains are significantly refined, the microstructure is uniform, and the overall structure is mainly α′ phase, with some α and β phases. After subsequent aging treatment, it has good mechanical properties. The good mechanical properties are attributed to the grain refinement strengthening caused by significant grain refinement, the precipitation strengthening of α and β phases, and the dislocation strengthening caused by lattice distortion. During the overall processing, the unstable α′ phase is well preserved, the microstructure is uniform, it has strong subsequent processability, and continuous production can be achieved.

Description

Technical Field

[0001] The present invention belongs to the field of alloy materials, and particularly relates to a high-performance α+β+α′ three-phase Ti-13Nb-13Zr alloy and a preparation method thereof. Background Art

[0002] With the development of biomedicine, the requirements for biomedical implants are increasing day by day. The low strength and high modulus of traditional implants will cause a series of problems such as stress shielding and cytotoxicity after the implants serve for a period of time, which will cause discomfort reactions in the human body and reduce the service life of the materials. Therefore, finding an implant material with high strength, low modulus and non-toxicity has become a key problem to be solved urgently.

[0003] Titanium is located in Group IVB of the periodic table, with a density of 4.51 g / cm 3 , belonging to light alloys. Its main characteristics are poor electrical conductivity (only 3.1% of Cu), low thermal expansion coefficient (comparable to glass), and high specific strength; as an implant material, the advantage of titanium and titanium alloys implanted in the human body is that they are non-magnetic and are less affected by the weather environment after being implanted in the human body, especially they will not be magnetized during thunderstorm weather.

[0004] The Ti-13Nb-13Zr alloy is a new type of biomedical titanium alloy developed by Smith&Richards company in the early 1990s. The added niobium element and zirconium element are known as "biological metal elements" and are widely used in biomedical implants. As a β-Ti phase stabilizing element, the presence of niobium element in titanium alloy can not only reduce the elastic modulus of titanium alloy but also improve the strength of titanium alloy. Moreover, niobium is a β-Ti isomorphous element and can be infinitely dissolved in β-phase Ti element; the atomic radii of niobium element and titanium element are not very different, and the lattice distortion of titanium after solid solution is less affected. Therefore, the addition of niobium element in the titanium matrix can strengthen the alloy without significantly reducing the plasticity of the material, and no eutectoid reaction and peritectoid reaction will occur between titanium element and niobium element. Therefore, no brittle phase alloy or compound will be formed between the two elements, which is very beneficial to the tissue stability of the material.

[0005] As a new type of biomedical titanium alloy, Ti-13Nb-13Zr has the same complex phase transformation as ordinary titanium alloys, with more than 6 different phases, such as α, β, α′, α″, β 转 , ω and other various phases. Among them, the ω phase belongs to the brittle phase, which will deteriorate the mechanical properties. The α phase belongs to the hard phase, and a certain amount of α phase can improve the mechanical properties of the material well. And the α variant phases such as α′, α″, β, β 转 are softer and have relatively balanced mechanical properties.

[0006] At present, medical implants mainly have two deficiencies. One is that the strength needs to be further improved, and the other is that the elastic modulus is too high and needs to be reduced. That is to say, under the premise of ensuring a certain strength, a certain plasticity is also required. Summary of the Invention

[0007] In order to solve the above technical problems, the present invention provides an α+β+α′ three-phase Ti-13Nb-13Zr alloy and a preparation method thereof. The purpose of the present invention is to provide a process method and parameters with relatively balanced performance, cost savings and continuous production, and obtain a Ti-13Nb-13Zr alloy with ultrafine grains, balanced performance and certain subsequent processability.

[0008] The present invention prepares the Ti-13Nb-13Zr alloy by composite cold working and aging treatment, and the implementation is as follows:

[0009] (1) The Ti-13Nb-13Zr alloy bar is subjected to solution treatment at 750°C for 40 minutes and then water quenched to induce rapid cooling.

[0010] Among them, the β-phase transformation temperature of the Ti-13Nb-13Zr alloy is 735°C. Solution treatment at 750°C can induce the formation of a fully β structure. The primary temperature of martensite is 550°C, and the end temperature is 485°C. In the subsequent rapid cooling stage caused by water quenching, the fully β structure transforms into a fully α′ structure.

[0011] (2) The alloy is subjected to one to four passes of continuous equal-channel angular pressing, the channel angle is 90°, the adiabatic temperature (the maximum temperature caused by the heat generated during the pressing process, not the heating temperature) is about 400°C - 430°C, the feeding speed is 16 mm / s, the alloy is at room temperature when input, and there is no cooling when output.

[0012] (3) Use water sandpapers of #240, #600, #1200, and #2500 to polish the surface until the roughness ≤ 20 μm to make the surface relatively smooth.

[0013] (4) The alloy is subjected to rotary forging. The number of chucks of the forging machine is 4, the rotation speed of the chucks is 46 r / min, the axial feeding speed is 16 mm / s, the hammering speed is 40 mm / min, there is no cooling in the output area, and the temperature generated during the rotary forging process ≤ 300°C.

[0014] (5) The processed alloy is subjected to aging treatment at 550°C for 1 - 6 h and cooled by air cooling.

[0015] The process of continuous equal-channel angular pressing and rotary forging used in the present invention is combined to prepare a high-strength Ti-13Nb-13Zr alloy. Through subsequent aging treatment, an α+β+α′ three-phase structure is obtained, which can not only retain high strength, have a certain plasticity, but also have good subsequent workability, and continuous production can be achieved. The Ti-13Nb-13Zr alloy bar prepared by this method has a smooth surface, uniform and dense structure, and good mechanical property matching.

[0016] The solution treatment is to obtain a fully metastable β-phase structure, and the temperature is selected 15° above the β-phase transformation temperature. The subsequent quenching treatment is to induce the generation of the α′ phase. The α′ phase has a relatively lower elastic modulus and greatly increases the subsequent workability, making the overall mechanical compatibility of the material more excellent.

[0017] The main advantages of the present invention are:

[0018] (1) The present invention provides a method for preparing an ultrafine-grained Ti-13Nb-13Zr alloy bar with good strength and plasticity matching. The composite material prepared by this method is applied in the biomedical field, greatly improving the mechanical properties and better meeting the performance requirements of clinical implants.

[0019] (2) The present invention provides a new process combination that can obtain an ultrafine-grained three-phase structure, which combines continuous equal-channel angular pressing, rotary forging and aging treatment. The mechanical processing process does not require high-temperature treatment, can better achieve continuous production and has excellent performance.

[0020] (3) The Ti-13Nb-13Zr alloy bar prepared by the present invention has excellent performance. The tensile strength of the Ti-13Nb-13Zr alloy bar can reach up to 1027 MPa at most, and can maintain an elongation of 10.2%. Most of the lath-shaped α′ martensite structure is retained, and it has strong subsequent workability. Description of the Drawings

[0021] Figure 1 SEM image of the surface microstructure of the Ti-13Nb-13Zr alloy after the combined process in Example 4.

[0022] Figure 2 TEM image of the surface microstructure of the Ti-13Nb-13Zr alloy after the combined process in Example 4.

[0023] Figure 3 High-resolution image and electron diffraction pattern in the β-phase of the Ti-13Nb-13Zr alloy after the combined process in Example 4, Figure 3 (a) is the morphology diagram of the β-phase and the precipitated α-phase therein, Figure 3 (b, c) are its high-resolution images, Figure 3(d) is the electron diffraction pattern, from which it can be seen that there are α-phase and β-phase.

[0024] Figure 4 Compare the TEM images of the surface microstructure of the Ti-13Nb-13Zr alloy after the combined process in Example 2. Specific implementation manners

[0025] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

[0026] Example 1

[0027] After subjecting the Ti-13Nb-13Zr alloy bar to solution treatment at 750 °C for 40 minutes, water quenching is carried out. After complete cooling, it is put into a continuous equal-channel angular pressing machine for continuous equal-channel angular pressing. After one pass of pressing, the diameter of the bar is reduced from the initial 10 mm to 8 mm. After using water sandpaper to polish the surface to make it relatively smooth, it is put into a rotary forging machine for rotary forging to obtain a bar with a diameter of 5.2 mm, a relatively smooth, relatively flat surface, and slightly bent. Then it is put into a vacuum tube furnace for aging treatment at 550 °C for 1 h. The final tensile strength is 1098 MPa, the elongation is 8.1%, and the average grain size is 149 nm.

[0028] Among them, the parameters of continuous equal-channel angular pressing are: the channel angle is 90°, the adiabatic temperature is 450 °C, the feeding speed is 16 mm / s, the bar is at room temperature when input, and there is no cooling when output. The water sandpaper is selected as #240, #600, #1200, #2500. The parameters of rotary forging are 4 chucks, the chuck rotation speed is 46 r / min, the axial feeding speed is 16 mm / s, the hammering speed is 40 mm / min, and there is no cooling in the output area. The aging treatment is put into the furnace when the temperature rises to 550 °C and is air-cooled after completion.

[0029] Example 2

[0030] After subjecting the Ti-13Nb-13Zr alloy bar to solution treatment at 750 °C for 40 minutes, water quenching is carried out. After complete cooling, it is put into a continuous equal-channel angular pressing machine for continuous equal-channel angular pressing. After two passes of pressing, after using water sandpaper to polish the surface to make it relatively smooth, it is put into a rotary forging machine for rotary forging to obtain a bar with a diameter of 5.2 mm, a relatively smooth, relatively flat surface, and slightly bent. Then it is put into a vacuum tube furnace for aging treatment at 550 °C for 1 h. The final tensile strength is 1112 MPa, the elongation is 7.3%, and the average grain size is 149 nm.

[0031] Example 3

[0032] After solution treatment of the Ti-13Nb-13Zr alloy bar at 750 °C for 40 minutes, water quenching was carried out. After complete cooling, it was put into a continuous equal-channel angular extrusion machine for continuous equal-channel angular extrusion. After four passes of extrusion, the diameter of the bar decreased from the initial 10 mm to 8 mm. After using water sandpaper to polish the surface to make it relatively smooth, it was put into a rotary forging machine for rotary forging, obtaining a bar with a diameter of 5.2 mm, a relatively smooth and flat surface, and slightly bent. Then it was put into a vacuum tube furnace for aging treatment at 550 °C for 1 h. The final tensile strength was 1119 MPa, the elongation was 7.1%, and the average grain size was 132 nm.

[0033] Example 4

[0034] After solution treatment of the Ti-13Nb-13Zr alloy bar at 750 °C for 40 minutes, water quenching was carried out. After complete cooling, it was put into a continuous equal-channel angular extrusion machine for continuous equal-channel angular extrusion. After one pass of extrusion, the diameter of the bar decreased from the initial 10 mm to 8 mm. After using water sandpaper to polish the surface to make it relatively smooth, it was put into a rotary forging machine for rotary forging, obtaining a bar with a diameter of 5.2 mm, a relatively smooth and flat surface, and slightly bent. Then it was put into a vacuum tube furnace for aging treatment at 550 °C for 2 h. The final tensile strength was 1027 MPa, the elongation was 10.2%, and the average grain size was 153 nm. The microstructure morphology is as Figure 1 、 Figure 2 shown, and the high-resolution image and electron diffraction pattern are as Figure 3 shown.

[0035] Figure 2 The white lamellar in is the α′ phase, accounting for a large proportion, the dark black is the β phase, and the gray-black part is the precipitate of the mixed α phase and β phase.

[0036] The process parameters are the same as those in Example 1.

[0037] Example 5

[0038] After subjecting the Ti-13Nb-13Zr alloy bar to solution treatment at 750 °C for 40 minutes, water quenching was carried out. After complete cooling, it was placed in a continuous equal-channel angular pressing machine for continuous equal-channel angular pressing. After one pass of pressing, the diameter of the bar decreased from the initial 10 mm to 8 mm. After using water sandpaper to polish the surface to make it relatively smooth, it was placed in a rotary forging machine for rotary forging, obtaining a bar with a diameter of 5.2 mm, a relatively smooth and flat surface, and slightly bent. Then it was placed in a vacuum tube furnace for aging treatment at 550 °C for 4 h. The final tensile strength was 905 MPa, the elongation was 8.9%, and the average grain size was 167 nm.

[0039] The process parameters are the same as those in Example 1.

[0040] Example 6

[0041] After subjecting the Ti-13Nb-13Zr alloy bar to solution treatment at 750 °C for 40 minutes, water quenching was carried out. After complete cooling, it was placed in a continuous equal-channel angular pressing machine for continuous equal-channel angular pressing. After one pass of pressing, the diameter of the bar decreased from the initial 10 mm to 8 mm. After using water sandpaper to polish the surface to make it relatively smooth, it was placed in a rotary forging machine for rotary forging, obtaining a bar with a diameter of 5.2 mm, a relatively smooth and flat surface, and slightly bent. Then it was placed in a vacuum tube furnace for aging treatment at 550 °C for 6 h. The final tensile strength was 821 MPa, the elongation was 11.7%. The average grain size was 191 nm.

[0042] The process parameters are the same as those in Example 1.

[0043] Comparative Example 1

[0044] After subjecting the Ti-13Nb-13Zr alloy bar to solution treatment at 750 °C for 40 minutes, water quenching was carried out. After complete cooling, it was placed in a continuous equal-channel angular pressing machine for continuous equal-channel angular pressing. After one pass of pressing, the diameter of the bar decreased from the initial 10 mm to 8 mm. Then it was placed in a vacuum tube furnace for aging treatment at 550 °C for 2 h. The final tensile strength was 782.9 MPa, the elongation was 19.1%. The average grain size was 489 nm.

[0045] Comparative Example 2

[0046] After solution treatment of the Ti-13Nb-13Zr alloy bar at 750 °C for 40 minutes, water quenching is carried out. After complete cooling, it is put into a continuous equal-channel angular pressing machine for continuous equal-channel angular pressing. After one pass of pressing, the diameter of the bar is reduced from the initial 10 mm to 8 mm. After using water sandpaper to polish the surface to make it relatively smooth, it is put into a rotary forging machine for rotary forging, obtaining a bar with a diameter of 5.2 mm, a relatively smooth and flat surface, and slightly bent. Then it is put into a vacuum tube furnace for aging treatment at 400 °C for 2 h. The final tensile strength is 1249 MPa, and the elongation is 3%. The average grain size is 131 nm. The microstructure morphology is as Figure 4 shown

[0047] Comparative Example 3

[0048] After solution treatment of the Ti-13Nb-13Zr alloy bar at 750 °C for 40 minutes, water quenching is carried out. After complete cooling, it is put into a continuous equal-channel angular pressing machine for continuous equal-channel angular pressing. After one pass of pressing, the diameter of the bar is reduced from the initial 10 mm to 8 mm. After using water sandpaper to polish the surface to make it relatively smooth, it is put into a rotary forging machine for rotary forging, obtaining a bar with a diameter of 5.2 mm, a relatively smooth and flat surface, and slightly bent. Then it is put into a vacuum tube furnace for aging treatment at 700 °C for 2 h. The final tensile strength is 1091 MPa, and the elongation is 3.5%. The average grain size is 142 nm.

[0049] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered within the protection scope of the present invention.

[0050] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered within the protection scope of the present invention.

Claims

1. A preparation method of an α + β + α′ three-phase Ti-13Nb-13Zr alloy, characterized in that, The preparation method has the following operating steps: Step 1: Solution-treat the Ti-13Nb-13Zr alloy bar, and then perform water quenching; The temperature of the solution treatment is 750°C, and the holding time is 40 min; Step 2: Perform continuous equal-channel angular pressing on the alloy; The number of passes of the continuous equal-channel angular pressing is: 1-4 passes, the feeding speed of the continuous equal-channel angular pressing is 16 mm / s, and there is no cooling in the output area; Step 3: Use water sandpaper to polish the surface and perform rotary forging on the alloy; Step 4: Perform aging treatment on the processed alloy; The aging temperature: 550°C, the aging time is 1-6 h.

2. The preparation method of the α+β+α′ three-phase Ti-13Nb-13Zr alloy according to claim 1, characterized in that, During the continuous equal-channel angular pressing process, the adiabatic temperature generated is 400°C - 430°C.

3. The preparation method of the α+β+α′ three-phase Ti-13Nb-13Zr alloy according to claim 1, characterized in that, The rotary forging has 4 chucks, and the rotation speed is 46 r / min.

4. The preparation method of the α+β+α′ three-phase Ti-13Nb-13Zr alloy according to claim 1, characterized in that, Before the rotary forging, the surface needs to be polished to a roughness ≤ 20 μm.

5. The preparation method of the α+β+α′ three-phase Ti-13Nb-13Zr alloy according to claim 1, characterized in that, The temperature generated during the rotary forging process ≤ 300°C.

6. An α+β+α′ three-phase Ti-13Nb-13Zr alloy prepared by the method according to any one of claims 1-5.

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