Titanium-oxygen-copper alloy with transition from columnar crystal to equiaxed crystal and strong plasticity and preparation method thereof

Abstract

The application relates to a titanium-oxygen-copper alloy with columnar crystal transformation to equiaxed crystal and strong plasticity and a preparation method, the titanium-oxygen-copper alloy is Ti-xCu-yO, the weight percentage content ratio of Cu in the titanium-oxygen-copper alloy is 2.6<=x<=3.2, and the weight percentage content ratio of O in the titanium-oxygen-copper alloy is 0.3<y<=0.5. The application also provides a preparation method and application of the titanium-oxygen-copper alloy. The oxygen content of the application is obtained by theoretical calculation, and the oxygen content may be increased in the process of printing and powder drying treatment. The titanium-oxygen-copper alloy of the titanium-oxygen-copper ternary system constructed by the application has the characteristics of columnar crystal transformation to equiaxed crystal and strong plasticity, overcomes the non-uniform distribution of original beta organization, Ti2Cu and face-centered cubic (FCC) phase caused by heat cycle, and has the advantages of low cost, high strength and toughness and isotropy.

Description

Technical Field

[0001] This invention belongs to the field of titanium-oxygen copper alloy preparation technology, and specifically relates to titanium-oxygen copper alloys with both columnar crystal to equiaxed crystal transformation and high plasticity, as well as their preparation methods. Background Technology

[0002] Among many materials, Ti-6Al-4V alloy is favored for its low density, good biocompatibility and excellent mechanical properties, making it the preferred material for hip joint prostheses in clinical applications.

[0003] However, traditionally manufactured Ti-6Al-4V alloy implants are difficult to personalize for individual patients, often requiring them to be "cut to fit." To reduce patient suffering, implants that are compatible with the human skeleton are crucial. LPBF (Laser-Based Biofilm Fusion) is a smart manufacturing technology based on the discrete / stacking principle, capable of directionally melting powder layer by layer using a high-energy laser beam to achieve personalized customization of complex metal implant structures. However, the unique thermal history of this technology (strong temperature gradients, high cooling rates, and thermal cycling, etc.) causes the titanium alloy to epitaxially grow large columnar crystals along the construction direction during solidification, severely affecting the mechanical properties of the Ti-6Al-4V alloy and leading to significant anisotropy. Therefore, promoting the transformation of columnar crystals to equiaxed crystals (CET) is key to ensuring implant performance and advancing the biomedical applications of additive manufacturing technology.

[0004] To address the columnar crystal problem in non-equilibrium solidification, based on the interdependence theory proposed by St. John et al., the grain size d of the molten metal during solidification... gs It is inversely proportional to the Q value, i.e., d gs = a + b / Q. The specific value of Q is determined by the formula Q = mC0(k-1), which actually reflects the development rate of the compositional supercooling zone and is related to the type of solute and its content in titanium. High-Q nickel (14.3C0) can increase compositional supercooling and promote CET, but its addition content is limited; introducing only 1.6 wt.% nickel into titanium will lead to brittle fracture. Experimental studies show that although the deposited Ti-8.5Cu alloy (Q = 62K) with a fully equiaxed grain structure can achieve complete CET, its elongation is only 2.1%, highlighting the limitation of the traditional titanium-copper system in synergistic strength and plasticity. The results indicate that titanium-copper alloys cannot simultaneously achieve both CET and strength and plasticity. Therefore, developing new titanium-based alloys with both high-efficiency CET capability and excellent strength-plasticity matching has important theoretical value and engineering significance. Summary of the Invention

[0005] To address the shortcomings of the prior art, the present invention aims to provide a low-cost titanium-oxygen copper alloy and its preparation method that combines columnar crystal to equiaxed crystal transformation with strong plasticity, thereby promoting the transformation of columnar crystals to equiaxed crystals while also giving the alloy material strong plasticity.

[0006] To solve the above technical problems, an implementation solution provided by the present invention is to provide a low-cost titanium-oxygen-copper alloy that takes into account the transformation from columnar crystals to equiaxed crystals and high strength and plasticity. The titanium-oxygen-copper alloy is Ti-xCu-yO, where x is the weight percentage ratio of Cu in the titanium-oxygen-copper alloy, and 2.6 ≤ x ≤ 3.2, and y is the weight percentage ratio of O in the titanium-oxygen-copper alloy, and 0.3 < y ≤ 0.5.

[0007] The present invention also provides a preparation method for a titanium-oxygen-copper alloy that takes into account the transformation from columnar crystals to equiaxed crystals and high strength and plasticity, including the following steps:

[0008] Select titanium powder and copper powder according to the weight percentage ratio x of Cu in the titanium-oxygen-copper alloy satisfying 2.6 ≤ x ≤ 3.2, and the weight percentage ratio y of O in the titanium-oxygen-copper alloy satisfying 0.3 < y ≤ 0.5;

[0009] Mix the titanium powder and copper powder to obtain a mixed powder;

[0010] Under an argon atmosphere, use a laser as a heat source to melt the mixed powder. After melting, the mixed powder is subjected to single-layer and single-pass LPBF laser additive manufacturing. After the LPBF laser additive manufacturing is completed, it is cooled to room temperature under an argon atmosphere to obtain a titanium-oxygen-copper alloy.

[0011] Preferably, the oxygen content of the titanium powder is 2000 ppm to 4000 ppm, and the oxygen content of the copper powder is 200 ppm to 1000 ppm.

[0012] Preferably, when the oxygen content of both the titanium powder and the copper powder is lower than 500 ppm, titanium dioxide powder needs to be added to make the O in the prepared titanium-oxygen-copper alloy within the range of 0.3 < y ≤ 0.5.

[0013] Preferably, during laser melting, the powder spreading thickness of the mixed powder is 28 μm to 32 μm. Before the mixed powder is subjected to single-layer and single-pass LPBF laser additive manufacturing, the substrate needs to be preheated, and the preheating temperature of the substrate is 190°C to 210°C.

[0014] Preferably, the particle size of the titanium powder is 15 μm to 53 μm, and the particle size of the copper powder is 5 μm to 53 μm.

[0015] Preferably, the printing parameters are: the laser scanning power is 180 W to 210 W, the laser scanning speed is 900 mm / s to 1100 mm / s, and the energy density absorbed per unit volume is 80 J / mm [[ID=3]] 3 ~85 J / mm 3 .

[0016] The present invention also provides an application of a low-cost titanium-oxygen-copper alloy that takes into account the transformation from columnar crystals to equiaxed crystals and strong plasticity in the preparation of hip joint implant medical devices.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] The titanium-oxygen-copper alloy of the titanium-oxygen-copper ternary system constructed by the present invention takes into account the characteristics of the transformation from columnar crystals to equiaxed crystals and strong plasticity, overcomes the non-uniform distribution of the original β phase, Ti2Cu and face-centered cubic (FCC) phase caused by thermal cycling, and has the advantages of low cost, high strength and toughness, and isotropy.

[0019] When the Ti-xCu-yO alloy provided by the present invention is compared with the Ti-6Al-4V alloy provided in the prior art, adding a small amount of copper element with a weight percentage ratio of 2.6 ≤ x ≤ 3.2 in the titanium-oxygen-copper alloy can produce solid solution strengthening, which helps to improve the strength and plasticity of the titanium-oxygen-copper alloy material, but CET and strong plasticity cannot act synergistically; after adding oxygen element with a weight percentage ratio of 0.3 < y ≤ 0.5 in the titanium-copper alloy, the titanium-oxygen-copper alloy takes into account the promotion of the transformation from columnar crystals to equiaxed crystals while also making the alloy material have strong plasticity. This is because the oxygen element in the titanium-oxygen-copper alloy has excellent nucleation ability and strengthening effect, and the titanium alloy is very sensitive to the oxygen content, which can significantly improve the strength of the alloy material. As an α-phase stabilizer, oxygen forms a locally oxygen-rich region in the titanium matrix, significantly expanding the composition supercooling region in the molten pool, inhibiting the growth of columnar crystals and promoting the nucleation of equiaxed crystals, and by changing the surface tension gradient of the molten pool, regulating the direction of Marangoni flow, making the solute distribution more uniform, reducing segregation, and providing a uniform solidification environment for the formation of equiaxed crystals. Therefore, the titanium-oxygen-copper alloy is expected to take into account CET while also making the alloy's strong plasticity act synergistically. Through this multi-solute synergistic effect, a titanium-oxygen-copper alloy with low cost, high strength and toughness, and isotropy is prepared.

[0020] Using LPBF laser additive manufacturing can prepare ultrafine-grained titanium alloy, effectively reducing oxygen segregation at grain boundaries, reducing local plastic deformation within the grains, and inhibiting crack formation. This enables titanium to tolerate a higher content of dissolved oxygen, and the LPBF-formed pure titanium with an oxygen content of 0.7 wt.% still has an elongation of 15%. The oxygen element has a higher Q value (10.8C0), and every 0.1 wt.% of oxygen can also provide a strength contribution of 76 MPa to titanium. Brief Description of the Drawings

[0021] Figure 1 Mechanical tensile diagrams of Ti, Ti-3Cu, Ti-3Cu-0.3O, and Ti-3Cu-0.5O materials.

[0022] Figure 2This is an electron backscatter diffraction (EBSD) pattern, in which... Figure 2 a is the inverse pole figure of pure Ti; Figure 2 e is the size angle grain boundary diagram of pure Ti; Figure 2 i is the grain reconstruction diagram of pure Ti; Figure 2 b is the inverse pole figure of Ti-3Cu; Figure 2 f is the grain boundary diagram of Ti-3Cu with large and small angles; Figure 2 j is the grain reconstruction diagram of Ti-3Cu; Figure 2 c represents the inverse pole figure of Ti-3Cu-0.3O. Figure 2 g represents the size angle grain boundary diagram of Ti-3Cu-0.3O; Figure 2 k is the grain reconstruction diagram of Ti-3Cu-0.3O; Figure 2 d is the inverse pole figure of Ti-3Cu-0.5O; Figure 2 h represents the size angle grain boundary diagram of Ti-3Cu-0.5O; Figure 2 l is a grain reconstruction diagram of Ti-3Cu-0.5O.

[0023] Figure 3 Physical images of LPBF laser additive manufacturing of Ti-3Cu, Ti-3Cu-0.3O, and Ti-3Cu-0.5O. Detailed Implementation

[0024] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. Unless otherwise specified, the experimental methods described in the embodiments of the present invention are conventional methods.

[0025] The inventors found that by using laser powder bed fusion (LPBF) for additive manufacturing to prepare interstitial oxygen-strengthened copper-modified titanium alloys, an optimization plan for composition and parameters that can both promote columnar-to-equiaxed transition (CET) and ensure the strength and plasticity of the alloy was explored. Overcoming the non-uniform distribution of the original β-phase, Ti2Cu, and FCC phase caused by thermal cycling and achieving the printing of high-performance isotropic titanium alloys are important problems that need to be solved urgently. This is because the titanium-copper alloys prepared by the LPBF technology exhibit significant non-uniformity in their microstructures under the action of rapid solidification and complex thermal cycling. This non-uniformity is mainly reflected in the distribution of the original β-phase, Ti2Cu intermetallic compounds, and FCC phase. Due to the high cooling rate and local temperature gradient during the LPBF process, part of the original β-phase may be retained or undergo martensitic transformation during solidification, forming non-equilibrium structures. At the same time, the solubility of copper in the titanium matrix is limited, and Ti2Cu phases are likely to precipitate during subsequent thermal cycling. These precipitated phases often show non-uniform distribution, further affecting the mechanical properties of the material. In addition, thermal cycling may also lead to the formation of FCC structures in local areas. The non-uniform distribution of this phase may be closely related to the temperature field and compositional segregation in the molten pool. The non-uniform distribution of the above microstructures not only affects the strength-plasticity matching of titanium-copper alloys but may also have an important impact on their fatigue performance and fracture behavior. Therefore, in-depth research on the thermal cycling behavior of titanium-copper alloys prepared by LPBF and its influence on microstructural evolution is of great significance for optimizing material properties.

[0026] As Figure 3 shown, a titanium-oxygen-copper alloy that combines columnar-to-equiaxed transition and high strength and plasticity, the titanium-oxygen-copper alloy is Ti-xCu-yO, where x is the weight percentage ratio of Cu in the titanium-oxygen-copper alloy, and 2.6 ≤ x ≤ 3.2, y is the weight percentage ratio of O in the titanium-oxygen-copper alloy, and 0.3 < y ≤ 0.5.

[0027] A method for preparing a titanium-oxygen-copper alloy that combines columnar-to-equiaxed transition and high strength and plasticity includes the following steps: Select titanium powder and copper powder according to the weight percentage ratio x of Cu in the titanium-oxygen-copper alloy satisfying 2.6 ≤ x ≤ 3.2, and the weight percentage ratio y of O in the titanium-oxygen-copper alloy satisfying 0.3 < y ≤ 0.5;

[0028] After mixing the titanium powder and copper powder, place them in a vacuum environment below 10 -3 Pa for drying. The drying temperature is 200°C to 500°C, and the drying time is ≥ 8 hours to obtain the dried mixed powder;

[0029] In an argon atmosphere, a laser is used as a heat source to melt the mixed powder. After melting, the mixed powder is subjected to single-layer and single-pass LPBF laser additive manufacturing. After the LPBF laser additive manufacturing is completed, it is cooled to room temperature in an argon atmosphere to obtain a titanium-oxygen-copper alloy. Before LPBF laser additive manufacturing, the duration of filling the protective atmosphere is not less than 7 minutes to make the oxygen content in the forming chamber lower than 0.01%. During LPBF laser additive manufacturing, a one-way scanning layer-by-layer rotation of 67° is used for printing.

[0030] Preferably, the oxygen content of the titanium powder is 2000 ppm to 4000 ppm, and the oxygen content of the copper powder is 200 ppm to 1000 ppm.

[0031] The particle size of the titanium powder is 15 μm to 53 μm, and the particle size of the copper powder is 5 μm to 53 μm.

[0032] Here, the titanium powder with a particle size of 15 μm to 53 μm is selected because the titanium powder achieves an optimal balance among fluidity, melting efficiency, layer thickness adaptability, material utilization rate, and equipment compatibility, becoming the mainstream choice for additive manufacturing.

[0033] Here, the copper powder with a particle size of 5 μm to 53 μm is selected because the copper powder achieves an optimal balance among fluidity, melting efficiency, layer thickness adaptability, material utilization rate, and equipment compatibility, becoming the mainstream choice for additive manufacturing.

[0034] Preferably, when the oxygen content of both the titanium powder and the copper powder is lower than 500 ppm, titanium dioxide powder needs to be added to make the O in the prepared titanium-oxygen-copper alloy within the range of 0.3 < y ≤ 0.5.

[0035] Specifically, during LPBF laser additive manufacturing, the VED absorbed per unit volume is 50 J / mm 3 ~200 J / mm 3 . Preferably, the volume energy density is 80 J / mm 3 ~85 J / mm 3 .

[0036] Specifically, the parameters of the laser are as follows: the laser scanning power is 100 W to 200 W, and the laser scanning speed is 500 mm / s to 1000 mm / s. The preferred parameters are that the laser scanning power is 180 W to 210 W, and the laser scanning speed is 900 mm / s to 1100 mm / s.

[0037] Specifically, during laser melting, the powder spreading thickness of the mixed powder is 28 μm to 32 μm. The preferred powder spreading thickness of the mixed powder is 30 μm. Before the mixed powder undergoes single-layer and single-pass LPBF laser additive manufacturing, the substrate needs to be preheated, and the preheating temperature of the substrate is 190 °C to 210 °C.

[0038] Application of a titanium-oxygen copper alloy that combines columnar crystal transformation to equiaxed crystal and high plasticity in the manufacture of hip joint implantable medical devices.

[0039] The methods and steps described above can all obtain high-performance titanium-oxygen copper alloys produced by LPBF additive manufacturing. The following specific examples illustrate the preparation method of high-performance titanium-oxygen copper alloys produced by LPBF additive manufacturing.

[0040] Example 1

[0041] 31g of copper powder with an oxygen content of approximately 200ppm to 1000ppm and a particle size of 5μm to 53μm was added to 1000g of spherical titanium powder with an oxygen content of approximately 2000ppm to 4000ppm. The mixture was then thoroughly mixed and subjected to a vacuum of 10... -3 Below Pa, dry at any temperature between 200℃ and 500℃ for 8 hours. Then, place the mixed powder under an argon atmosphere and heat it with a 200W laser scanning power as the heat source, with a VED absorbed per unit volume of 80J / mm. 3 ~100J / mm 3 Any temperature is acceptable; here, the VED absorbed per unit volume is 83 J / mm. 3 Before heating, the substrate in LPBF laser additive manufacturing needs to be preheated to any temperature within the range of 190℃ to 210℃. Here, the substrate is preheated to 200℃. Single-layer, single-pass LPBF laser additive manufacturing is carried out under the conditions of a laser scanning speed of 1000mm / s, a powder layer thickness of 30μm, a laser scanning spacing of 80μm, and a unidirectional scanning layer rotation of 67°. After the LPBF laser additive manufacturing is completed, it is cooled to room temperature under an argon atmosphere to obtain the titanium-oxygen copper alloy Ti-3Cu-0.5O.

[0042] Example 2

[0043] The method for preparing high-performance titanium-oxygen copper alloys by additive manufacturing using LPBF includes the following steps:

[0044] To 1000g of spherical titanium powder with an oxygen content of less than 500ppm and a particle size of 15μm–53μm, 31g of copper powder with an oxygen content of less than 500ppm and a particle size of 5μm–53μm, and 10g of titanium dioxide powder with a purity of 99% and a particle size ≤10μm were added, the mixture was thoroughly mixed and then subjected to a vacuum of 10... -3 Below Pa, dry at any temperature between 200℃ and 500℃ for 8 hours. Then, place the mixed powder under an argon atmosphere and heat it with a 120W laser scanning power as the heat source, with a VED absorbed per unit volume of 80J / mm. 3 ~100J / mm3 Any temperature is acceptable; here, the VED absorbed per unit volume is 100 J / mm. 3 Before heating, the substrate in LPBF laser additive manufacturing needs to be preheated to any temperature within the range of 190℃ to 210℃. Here, the substrate is preheated to 200℃. The mixed powder after heating and melting is subjected to single-layer single-pass LPBF laser additive manufacturing under the conditions of laser scanning speed of 500mm / s, powder layer thickness of 30μm, laser scanning spacing of 80μm, and unidirectional scanning interlayer rotation of 67°. After LPBF laser additive manufacturing is completed, it is cooled to room temperature under argon atmosphere to obtain titanium-oxygen copper alloy Ti-3Cu-0.5O.

[0045] The differences between Examples 3 to 6 and Example 2 are only in the laser scanning power, laser scanning speed, and VED. The laser scanning power, laser scanning speed, and VED parameters for Examples 1 to 6 are detailed in Table 1.

[0046] Table 1 shows the laser parameters for Ti-3Cu-0.5O.

[0047] Serial Number Laser power (W) Scanning speed (mm / s) <![CDATA[VED(J / mm 3 ) <!-- 4 -->]]> Example 1 200 1000 83 Example 2 120 500 100 Example 3 140 625 93 Example 4 160 750 89 Example 5 180 875 86 Example 6 200 1000 83

[0048] Compare with Example 1

[0049] The method for preparing high-performance titanium-oxygen copper alloys by additive manufacturing using LPBF includes the following steps:

[0050] To 1000g of spherical titanium powder with an oxygen content of less than 500ppm and a particle size of 15μm–53μm, 31g of copper powder with an oxygen content of less than 500ppm and a particle size of 5μm–53μm, and 10g of titanium dioxide powder with a purity of 99% and a particle size ≤10μm were added, the mixture was thoroughly mixed and then subjected to a vacuum of 10... -3 Below Pa, the powder is dried at any temperature between 200℃ and 500℃ for 8 hours. Then, the mixed powder is placed in an argon atmosphere and heated with a 120W laser as the heat source at 50 J / mm². 3 ~200J / mm 3 Any temperature is acceptable; here, VED is set to 100 J / mm. 3 Before heating, the substrate in LPBF laser additive manufacturing needs to be preheated to any temperature within the range of 190℃ to 210℃. Here, the substrate is preheated to 200℃. The mixed powder after heating and melting is subjected to single-layer, single-pass LPBF laser additive manufacturing under the conditions of a laser scanning speed of 500mm / s, a powder layer thickness of 30μm, a laser scanning spacing of 80μm, and a unidirectional scanning layer rotation of 67°. After the LPBF laser additive manufacturing is completed, it is cooled to room temperature under an argon atmosphere to obtain the titanium-oxygen copper alloy Ti-3Cu-0.5O.

[0051] The only differences between Comparative Examples 2 to 5 and Comparative Example 1 are the laser scanning power, laser scanning speed, and VED. The corresponding laser scanning power, laser scanning speed, and VED parameters of Comparative Examples 1 to 5 are detailed in Table 2.

[0052] Table 2 shows the laser parameters for printing Ti-3Cu-0.3O.

[0053]

[0054]

[0055] Compare with Example 6

[0056] The method for preparing high-performance titanium-oxygen copper alloys by additive manufacturing using LPBF includes the following steps:

[0057] 1000g of spherical titanium powder with an oxygen content of less than 500ppm and a particle size of 15μm to 53μm was mixed with 31g of copper powder with an oxygen content of less than 500ppm and a particle size of 5μm to 53μm. The resulting mixture was then subjected to a vacuum of 10... -3 Below Pa, the titanium powder is dried at any temperature between 200℃ and 500℃ for 8 hours. Then, the mixed titanium powder is placed in an argon atmosphere and heated with a 120W laser as the heat source at 50 J / mm². 3 ~200J / mm 3 Any temperature is acceptable; here, the energy density absorbed per unit volume, VED, is 100 J / mm². 3 Before heating, the substrate in LPBF laser additive manufacturing needs to be preheated to any temperature within the range of 190℃ to 210℃. Here, the substrate is preheated to 200℃. After heating and melting, the mixed powder is used for single-layer, single-pass LPBF laser additive manufacturing under the conditions of a laser scanning speed of 500mm / s, a powder layer thickness of 30μm, a laser scanning spacing of 80μm, and a unidirectional scanning layer rotation of 67°. After the LPBF laser additive manufacturing is completed, it is cooled to room temperature under an argon atmosphere to obtain the titanium-oxygen copper alloy Ti-3Cu.

[0058] The only differences between Comparative Examples 7 to 10 and Comparative Example 6 are the laser scanning power, laser scanning speed, and VED. The corresponding laser scanning power, laser scanning speed, and VED parameters of Comparative Examples 6 to 10 are detailed in Table 3.

[0059] Table 3 shows the laser parameters for Ti-3Cu.

[0060]

[0061]

[0062] Compare with Example 11

[0063] The comparative example uses pure titanium and LPBF laser additive manufacturing. The LPBF laser additive manufacturing process uses a laser power of 200W, a scanning speed of 1000mm / s, and a VED of 83J / mm. 3 .

[0064] Experimental verification

[0065] Materials obtained from Examples 1 to 6 above can all be produced by LPBF laser additive manufacturing. Below, materials obtained from Examples 2 to 6 and Comparative Examples 1 to 11 above using LPBF laser additive manufacturing (e.g.) Figure 3 As shown in the figure, the experimental tensile samples obtained by wire cutting were then polished. During polishing, each experimental tensile sample was sequentially polished with sandpaper of 80 grit, 220 grit, 400 grit, 800 grit, 100 grit, and 1500 grit. After polishing, tensile tests were performed. The tensile test data of Examples 1 to 6 are shown in Table 4.

[0066] Table 4 shows the tensile test data values ​​for Examples 1 to 6.

[0067]

[0068] The test results of Comparative Examples 1-5, 10, and 11 are shown in Table 5 below. (Comparative Example 10 was selected from the experimental tensile samples obtained from Comparative Examples 6-10 for tensile testing.)

[0069] Table 5 shows the tensile test data values ​​for Comparative Examples 1 to 5, 10, and 11.

[0070]

[0071]

[0072] To more intuitively demonstrate the differences in mechanical properties of the above materials, materials prepared with the 6th group of laser parameters for Ti-3Cu-0.5O (Example 6), materials prepared with the 5th group of laser parameters for Ti-3Cu-0.3O (Control Example 5), materials prepared with the 5th group of laser parameters for Ti-3Cu (Control Example 10), and materials prepared with the 1st group of laser parameters for pure Ti (Control Example 11) were selected for tensile test performance demonstration and EBSD analysis.

[0073] (1) Results of tensile test

[0074] like Figure 1 As shown, from Figure 1It was found that, under the same parameters, the introduction of 3% Cu resulted in a strong solid solution strengthening effect due to the solid solution-induced lattice distortion of copper atoms, which improved the strength of the material. However, the plasticity decreased due to the obstruction of dislocation movement. The introduction of oxygen element improved the comprehensive performance of the material through a dual mechanism. When the oxygen content increased to 0.5%, the solid solution strengthening of oxygen atoms in the matrix further increased the strength. At the same time, its grain boundary segregation characteristics significantly enhanced the grain boundary binding energy. By inhibiting grain boundary slip and crack propagation and promoting dynamic recrystallization to form a submicron-level equiaxed crystal structure, the strength was greatly improved while only a small part of the plasticity was lost. This proves that the appropriate addition of solute oxygen element and copper element can achieve the transformation of columnar equiaxed crystal and the synergistic effect of strengthening and toughening in titanium-oxygen copper alloy.

[0075] (2) Electron backscattering diffraction measurement results

[0076] like Figure 2 As shown, Figure 2 The grains in the same row become increasingly finer from left to right. Compared to the Ti-3Cu-0.3O and Ti-3Cu samples, the Ti-3Cu-0.5O sample exhibits a more uniform and finer original β-structure, with a higher proportion of equiaxed crystals. This demonstrates that the appropriate addition of oxygen and copper elements can achieve a transformation from columnar to equiaxed crystals in a titanium-oxygen copper alloy, resulting in a synergistic strengthening and toughening effect.

[0077] The addition of Cu significantly reduced small grain boundaries and substantially increased the original β grain size. This is because the addition of Cu inhibited dislocation movement and recrystallization, reducing the formation of small-angle grain boundaries. Cu solid solution strengthening further improved strength. Since grain coarsening reduced the obstruction of dislocation movement by grain boundaries, Cu solid solution strengthening limited dislocation movement, leading to a decrease in plasticity. However, the addition of oxygen, as seen in the comparison of the k, l, and j diagrams, showed a reduction in the original β grain size. This is mainly because oxygen atoms segregated at the solid-liquid interface, hindering atomic stacking at the solid phase front, slowing down the grain growth rate, and resulting in a smaller grain size.

[0078] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A titanium-oxygen copper alloy that combines columnar crystal transformation to equiaxed crystal structure and high plasticity, characterized in that, Titanium-oxygen copper alloy is Ti- x Cu- y O, where x The value represents the weight percentage of Cu in the titanium-oxygen copper alloy, and 2.6 ≤ x ≤3.2, y The weight percentage of oxygen in the titanium-oxygen copper alloy is 0.3, and 0.3 < y ≤0.

5.

2. The method for preparing the titanium-oxygen copper alloy with both columnar crystal transformation to equiaxed crystal structure and high plasticity according to claim 1, characterized in that, Includes the following steps: According to the weight percentage of Cu in the titanium-oxygen copper alloy x Satisfying 2.6≤ x ≤3.2, and the weight percentage of O in the titanium-oxygen copper alloy. y Satisfying 0.3 < y For a concentration ≤0.5, titanium powder and copper powder are preferred. Titanium powder and copper powder are mixed to obtain a mixed powder; Under an argon atmosphere, a laser is used as a heat source to melt mixed powder. The molten mixed powder is then subjected to single-layer, single-pass LPBF laser additive manufacturing. After the LPBF laser additive manufacturing is completed, it is cooled to room temperature under an argon atmosphere to obtain a titanium-oxygen copper alloy.

3. The method for preparing the titanium-oxygen copper alloy with both columnar crystal transformation to equiaxed crystal and high plasticity according to claim 2, characterized in that, The oxygen content of titanium powder is 2000ppm~4000ppm, and the oxygen content of copper powder is 200ppm~1000ppm.

4. The method for preparing the titanium-oxygen copper alloy with both columnar crystal transformation to equiaxed crystal and high plasticity according to claim 2, characterized in that, When the oxygen content of both titanium powder and copper powder is below 500 ppm, titanium dioxide powder needs to be added to ensure that the oxygen content in the prepared titanium-oxygen copper alloy is 0.3 ppm. y Within the range of ≤0.

5.

5. The method for preparing the titanium-oxygen copper alloy with both columnar crystal transformation to equiaxed crystal and high plasticity according to claim 2, characterized in that, During laser melting, the thickness of the mixed powder is 28μm~32μm. Before the mixed powder is used for single-layer single-pass LPBF laser additive manufacturing, the substrate needs to be preheated. The preheating temperature of the substrate is 190℃~210℃.

6. The method for preparing the titanium-oxygen copper alloy with both columnar crystal transformation to equiaxed crystal and high ductility according to claim 2, characterized in that, Titanium powder has a particle size of 15μm~53μm, and copper powder has a particle size of 5μm~53μm.

7. The method for preparing the titanium-oxygen copper alloy with both columnar crystal transformation to equiaxed crystal structure and high plasticity according to claim 2, characterized in that, The printing parameters are as follows: laser scanning power of 180W~210W, laser scanning speed of 900mm / s~1100mm / s, and energy density absorbed per unit volume of 80J / mm². 3 ~85J / mm 3 .

8. The application of the titanium-oxygen copper alloy of claim 1, which combines columnar crystal transformation to equiaxed crystal and high plasticity, in the preparation of hip joint implantable medical devices.

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