Titanium-oxygen-copper alloy with columnar crystal orientation isometric crystal transformation and strong plasticity and preparation method of titanium-oxygen-copper alloy

Abstract

The invention relates to a titanium-oxygen-copper alloy with columnar crystal orientation isometric crystal transformation and strong plasticity and a preparation method, the titanium-oxygen-copper alloy is Ti-xCu-yO, the weight percentage ratio of Cu to the titanium-oxygen-copper alloy is larger than or equal to 2.6 and smaller than or equal to 3.2, and the weight percentage ratio of O to the titanium-oxygen-copper alloy is 0.3 lt; and y < = 0.5. The invention further provides a preparation method and application of the titanium-oxygen-copper alloy. The oxygen content is obtained through theoretical calculation, and oxygenation is possible in the printing process and the powder drying process. According to the titanium-oxygen-copper alloy of the titanium-oxygen-copper ternary system, the characteristics of columnar crystal orientation isometric crystal transformation and high plasticity are considered, non-uniform distribution of an original beta structure, Ti2Cu and a face-centered cubic (FCC) phase caused by thermal circulation is overcome, and the titanium-oxygen-copper alloy has the advantages of being low in cost, high in toughness and isotropic.

Description

Technical Field

[0001] The invention belongs to the technical field of titanium oxide copper alloy preparation, and particularly relates to a titanium oxide copper alloy with columnar crystal to equiaxed crystal transformation and strong plasticity and a preparation method thereof. Background Art

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

[0003] However, Ti-6Al-4V alloy implants prepared by traditional processes are difficult to be personalized for patients, and clinical patients often need to "cut their feet to fit the shoes." In order to reduce the pain of patients, it is crucial to use implants that are coordinated with the human skeleton. LPBF is an intelligent manufacturing technology based on the discrete / stacking principle. It can achieve personalized customization of complex structure metal implants by layer-by-layer directionally melting powder through a high-energy laser beam. However, the unique thermal history of this technology (strong temperature gradient, high cooling rate and thermal cycle, etc.) will cause the titanium alloy to epitaxially grow coarse columnar crystals along the construction direction during the solidification process, seriously affecting the mechanical properties of the Ti-6Al-4V alloy and resulting in significant anisotropy. Therefore, promoting the transformation of columnar crystals to equiaxed crystals (CET) is the key to ensuring the performance of implant preparation and promoting the biomedical application of additive manufacturing technology.

[0004] In view of the problem of columnar crystals in the non-equilibrium solidification process, according to the interdependence theory proposed by StJohn et al., the grain size d gs Inversely proportional to the Q value, that is, d gs =a+b / Q. The specific size of the Q value is determined by the formula Q=mC0(k-1), which actually reflects the development speed of the composition supercooling zone and is related to the type of solute and its content in titanium. Nickel with a high Q value (14.3C0) can increase the composition supercooling and promote CET, but its added content is limited. Introducing only 1.6wt.% of nickel into titanium will cause the material to fracture brittlely. Experimental studies have shown that although the deposited Ti-8.5Cu alloy (Q=62K) with a fully equiaxed crystal structure can achieve complete CET, its elongation is only 2.1%, highlighting the limitations of the traditional titanium-copper system's strength-plasticity synergy. The results show that titanium-copper alloys cannot simultaneously take into account CET and strong plasticity. Therefore, the development of a new titanium-based alloy that has both efficient CET capabilities and excellent strength-plasticity matching has important theoretical value and engineering significance. Summary of the Invention

[0005] In view of the above-mentioned deficiencies of the prior art, the purpose of the present invention is to provide a low-cost titanium oxide copper alloy and a preparation method that combines the transformation from columnar crystal to equiaxed crystal and strong plasticity, which not only promotes the transformation from columnar crystal to equiaxed crystal but also makes the alloy material have 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 the 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 laying 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 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 high strength and 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 high strength and 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, toughness and isotropy.

[0019] Compared with the Ti-6Al-4V alloy given in the prior art, in the titanium-oxygen-copper alloy, 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 high strength and 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 promoting the transformation from columnar crystals to equiaxed crystals and also makes the alloy material have high strength and 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 high strength and plasticity of the alloy act synergistically. Through this multi-solute synergistic effect, a titanium-oxygen-copper alloy with low cost, high strength, 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 grains, and inhibiting crack formation. This allows 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 It is the mechanical tensile diagram of Ti, Ti-3Cu, Ti-3Cu-0.3O, and Ti-3Cu-0.5O materials.

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

[0023] Figure 3 Actual photos of LPBF laser additive manufacturing of Ti-3Cu, Ti-3Cu-0.3O, and Ti-3Cu-0.5O. DETAILED DESCRIPTION

[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 by the specific embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. The experimental methods described in the embodiments of the present invention are all conventional methods unless otherwise specified.

[0025] The inventors found that by using laser powder bed fusion (LPBF) to fabricate copper-modified titanium alloys strengthened by interstitial oxygen, an optimization scheme 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 is an important problem that亟待解决 (needs to be urgently solved) at present. This is because the microstructure of titanium-copper alloys prepared by the LPBF technique exhibits significant non-uniformity 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 compound, 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 a non-equilibrium structure. 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, and the non-uniform distribution of this phase may be closely related to the temperature field and compositional segregation in the melt 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 microstructure 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] Mix the titanium powder and copper powder and place them in a vacuum environment of 10 -3 pa or less 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 unidirectional 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, 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, 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 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. Preferably, the 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 oxide copper alloy with columnar to equiaxed crystal transformation and strong plasticity in the preparation of hip joint implant medical devices.

[0039] The above-mentioned method steps can all obtain LPBF additive manufacturing high-performance titanium-copper alloy. The following is a preparation method of LPBF additive manufacturing high-performance titanium-copper alloy with a specific embodiment.

[0040] Example 1

[0041] 31g of copper powder with an oxygen content of about 200ppm to 1000ppm and a particle size of 5μm to 53μm was added to 1000g of spherical titanium powder with an oxygen content of about 200ppm to 4000ppm and a particle size of 15μm to 53μm. The mixed powder was thoroughly mixed and placed in a vacuum chamber at 10 -3 Pa below, drying temperature is any temperature between 200 ℃ and 500 ℃ for 8 hours, then the mixed powder is placed in an argon atmosphere, and heated by a laser with a laser scanning power of 200W as a heat source, with the VED absorbed per unit volume being 80J / mm 3 ~100J / mm 3 Any temperature can be used, and the VED absorbed per unit volume is 83J / mm 3 Before heating, the substrate in LPBF laser additive manufacturing needs to be preheated to any temperature within the range of 190°C to 210°C. Here, the substrate is preheated to 200°C. The heated and melted mixed powder is subjected to single-layer single-pass LPBF laser additive manufacturing under the conditions of a laser scanning speed of 1000 mm / s, a powder layer thickness of 30 μm, a laser scanning spacing of 80 μm, and a unidirectional scanning interlayer rotation of 67°. After the LPBF laser additive manufacturing is completed, it is cooled to room temperature in an argon atmosphere to obtain a titanium oxide copper alloy Ti-3Cu-0.5O.

[0042] Example 2

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

[0044] 31g of copper powder with an oxygen content of less than 500ppm and a particle size of 5μm to 53μm was added to 1000g of spherical titanium powder with an oxygen content of less than 500ppm and a particle size of 15μm to 53μm; 10g of titanium dioxide powder with a purity of 99% and a particle size of ≤10μm was added to the mixture. The mixed powder was then placed in a vacuum of 10 -3 Pa below, drying temperature is any temperature between 200 ℃ and 500 ℃ for 8 hours, then the mixed powder is placed in an argon atmosphere, and heated by a laser with a laser scanning power of 120W as a heat source, with the VED absorbed per unit volume being 80J / mm 3 ~100J / mm3 Any temperature can be used, and 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°C to 210°C. Here, the substrate is preheated to 200°C. The heated and melted mixed powder is subjected to single-layer single-pass LPBF laser additive manufacturing at a laser scanning speed of 500 mm / s, a powder layer thickness of 30 μm, a laser scanning spacing of 80 μm, and a unidirectional scanning interlayer rotation of 67°. After the LPBF laser additive manufacturing is completed, it is cooled to room temperature in an argon atmosphere to obtain a titanium oxide copper alloy Ti-3Cu-0.5O.

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

[0046] Table 1 shows the laser parameters of 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] Comparative Example 1

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

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

[0051] The only difference between Control Examples 2 to 5 and Control Example 1 is the laser scanning power, laser scanning speed and VED. The corresponding laser scanning power, laser scanning speed and VED parameters of Control 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] Comparative Example 6

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

[0057] 31g of copper powder with an oxygen content of less than 500ppm and a particle size of 5μm to 53μm was added to 1000g of spherical titanium powder with an oxygen content of less than 500ppm and a particle size of 15μm to 53μm, and the mixed powder was thoroughly mixed and placed in a vacuum of 10 -3 Pa below, drying temperature is 200 ℃ ~ 500 ℃ any temperature drying for 8 hours, then the mixed titanium powder is placed in an argon atmosphere, and the laser power of 120W is used as the heat source to heat it, 50J / mm 3 ~200J / mm 3 Any temperature can be used, and the energy density 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 in the range of 190℃ to 210℃. Here, the substrate is preheated to 200℃. After heating and melting, the mixed powder is subjected to single-layer and single-pass LPBF laser additive manufacturing at a laser scanning speed of 500mm / s, a powder layer thickness of 30μm, a laser scanning spacing of 80μm, and a unidirectional scanning interlayer rotation of 67°. After the LPBF laser additive manufacturing is completed, it is cooled to room temperature under an argon atmosphere to obtain titanium oxide copper alloy Ti-3Cu.

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

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

[0060]

[0061]

[0062] Comparative Example 11

[0063] The material used in this comparative example is pure titanium, and LPBF laser additive manufacturing is performed. The laser power of LPBF laser additive manufacturing is 200W, the scanning speed is 1000mm / s, and the VED is 83J / mm 3 .

[0064] Experimental verification

[0065] The above-mentioned examples 1 to 6 can all be manufactured by LPBF laser additive manufacturing to obtain materials. The following examples 2 to 6 and comparative examples 1 to 11 are manufactured by LPBF laser additive manufacturing to obtain materials (such as Figure 3 The materials were then subjected to wire cutting to obtain experimental tensile specimens, which were then polished. Each experimental tensile specimen was sequentially polished using 80-mesh, 220-mesh, 400-mesh, 800-mesh, 100-mesh, and 1500-mesh sandpaper. After polishing, tensile testing was performed. The tensile test data for Examples 1 to 6 are shown in Table 4.

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

[0067]

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

[0069] Table 5 shows the tensile test data values ​​of Control Examples 1 to 5, 10, and 11

[0070]

[0071]

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

[0073] (1) Tensile test results

[0074] like Figure 1 As shown, from Figure 1It was found that under the same parameters, when 3% Cu was introduced, the solid solution of copper atoms induced lattice distortion to produce a strong solid solution strengthening effect, which increased the strength of the material, but the plasticity decreased due to the obstruction of dislocation movement; the intervention of oxygen elements improved the comprehensive performance of the material through a dual action 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, inhibited grain boundary slip and crack propagation, and promoted dynamic recrystallization to form a submicron equiaxed crystal structure. The strength was greatly improved while only a small part of the plasticity was lost. It was proved that the appropriate addition of solute oxygen and copper elements can achieve the transformation of columnar crystal phase to equiaxed crystal and the synergistic strengthening and toughening effect of titanium oxide copper alloy.

[0075] (2) Electron backscatter diffraction measurement results

[0076] like Figure 2 As shown, Figure 2 The grains in the same row become increasingly smaller from left to right. The original beta grains of the Ti-3Cu-0.5O sample are more uniform and finer than those of the Ti-3Cu-0.3O and Ti-3Cu samples. The Ti-3Cu-0.5O sample also contains a higher proportion of equiaxed grains than the Ti-3Cu-0.3O, Ti-3Cu, and pure Ti samples. This demonstrates that the appropriate addition of solute oxygen and copper can achieve the transformation from columnar to equiaxed phases and achieve synergistic strengthening and toughening of the titanium oxide copper alloy.

[0077] After adding Cu, the small grain boundaries are greatly reduced, and the original β grain size is greatly increased. This is because the addition of Cu inhibits dislocation movement and recrystallization, reducing the formation of small-angle grain boundaries. The solid solution strengthening of Cu further improves the strength. Since grain coarsening reduces the obstruction of grain boundaries to dislocation movement, the solid solution strengthening of Cu restricts dislocation movement, resulting in a decrease in plasticity. After the addition of oxygen, the original β grain size can be seen to be reduced from the comparison of the k, l and j graphs. This is mainly because oxygen atoms are segregated at the solid-liquid interface, hindering the atomic stacking at the solid phase front, slowing the grain growth rate, and reducing the grain size.

[0078] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims and their equivalents, the present invention is intended to include such modifications and variations.

Claims

1. A titanium-copper oxide alloy with both columnar to equiaxed crystal transformation and strong plasticity, characterized in that: 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.

2. The method for preparing a titanium oxide copper alloy having both columnar to equiaxed crystal transformation and strong plasticity according to claim 1, characterized in that: It 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; Mix the titanium powder and copper powder to obtain a mixed powder; Under an argon atmosphere, use 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 the titanium-oxygen-copper alloy.

3. The method for preparing a titanium oxide copper alloy having both columnar to equiaxed crystal transformation and strong plasticity according to claim 2, characterized in that: 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.

4. The method for preparing a titanium oxide copper alloy having both columnar to equiaxed crystal transformation and strong plasticity according to claim 2, characterized in that: 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.

5. The method for preparing a titanium oxide copper alloy having both columnar to equiaxed crystal transformation and strong plasticity according to claim 2, characterized in that: During laser melting, the powder laying thickness of the mixed powder is 28 μm to 32 μm. The substrate needs to be preheated before the mixed powder is subjected to single-layer and single-pass LPBF laser additive manufacturing, and the preheating temperature of the substrate is 190°C to 210°C.

6. The method for preparing a titanium oxide copper alloy having both columnar to equiaxed crystal transformation and strong plasticity according to claim 2, characterized in that: 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.

7. The method for preparing a titanium oxide copper alloy having both columnar to equiaxed crystal transformation and strong plasticity according to claim 2, characterized in that: Printing parameters are: laser scanning power of 180W to 210W, laser scanning speed of 900mm / s to 1100mm / s, and energy density absorbed per unit volume of 80J / mm 3 ~85J / mm 3 .

8. Application of the low-cost titanium-oxygen-copper alloy with both columnar crystal to equiaxed crystal transformation and high strength and plasticity as described in claim 1 in the preparation of hip joint implant medical devices.

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