A nitrogen-rich high-tenacity Ti-Nb alloy, a preparation method and application thereof

Abstract

This invention belongs to the field of biomedicine, specifically relating to a nitrogen-rich, high-strength, and tough Ti-Nb alloy, its additive manufacturing method, and its applications. The alloy comprises Ti, Nb, and N; wherein the atomic percentage of Nb is greater than 20% and less than 30%; and the mass percentage of N is 0.01 wt.% to 0.5 wt.%. The preparation method is as follows: raw material powders are mixed according to the designed composition in a nitrogen-containing protective atmosphere to obtain 3D printing powder. The powder is then printed layer by layer using a laser power of 180–220 W, a scanning speed of 300–800 mm / s, a scanning spacing of 80–120 μm, and a powder layer thickness of 25–45 μm. The scanning strategy involves an angle of 67° between each layer and the previous layer. The final product is obtained; the resulting alloy has a density of 99.8%. This invention features a simple composition system, a concise process, controllable preparation costs, and excellent product performance, making it suitable for use as orthopedic implant materials.

Description

Technical Field

[0001] This invention belongs to the field of biomedicine, and specifically relates to a nitrogen-rich, high-strength and high-toughness titanium-niobium alloy, its additive manufacturing method, and its application. Background Technology

[0002] Titanium alloys (such as Ti-6Al-4V) have been widely used in the biomedical field due to their excellent corrosion resistance and biocompatibility. However, their high elastic modulus can lead to stress shielding, and Al and V can cause biotoxicity. Currently, many non-biotoxic β-type titanium alloys have been developed. TiNb alloys, composed of two elements, exhibit good biocompatibility and hold promise for use as implant materials.

[0003] Selective laser melting (SLM) is a technique that allows for the customization of metal structural parts with complex shapes, offering advantages such as high geometric freedom and minimal material waste. During SLM, the rapid cooling rate in the molten pool leads to grain refinement. Simultaneously, the significant thermal stress generated during processing induces micro-strain, resulting in numerous dislocations and further enhancing the strength of titanium alloys. As the stability of the β phase decreases, the deformation mode shifts from dislocation slip to stress-induced martensitic transformation. Martensitic transformation leads to high yield strength (YS) but also brittleness, while dislocation slip produces low YS and good ductility. Therefore, balancing strength and ductility becomes a complex and contradictory issue.

[0004] Currently, research on SLM processing using mixed Ti and Nb elemental powders has attracted researchers' attention. Huang et al. (S.Huang, RL Narayan, JHK Tan, SLSing, WYYeong, Resolving the porosity-unmelted inclusion dilemma during in-situ alloying of Ti34Nb vialaser powder bed fusion, Acta Materialia 204(2021)116522.) studied the differences in porosity and microstructure between samples processed by SLM using Gaussian lasers and top-hat lasers. They found that top-hat laser-printed Ti-41Nb samples exhibited better compactness. However, most SLM equipment is equipped with conventional Gaussian beam profile lasers, and changing the laser profile would undoubtedly increase costs, limiting further industrial production applications. Studies have shown (J. Wang, Y. Liu, CDRabadia, S.-X. Liang, TBSercombe, L.-C. Zhang, Microstructural homogeneity and mechanical behavior of a selective laser melted Ti-35Nb alloy produced from an elemental powder mixture, Journal of Materials Science & Technology 61(2021)221-233.) that the Ti-35Nb alloy prepared by SLM technology has a yield strength of 648 MPa and a fracture elongation of 3.9%; another study (S. Huang, P. Kumar, WYYeong, RLNarayan, U. Ramamurty, Fracture behavior of laser powder bed fusion fabricated Ti41Nb via in-situ alloying, Acta Materialia) showed that the Ti-35Nb alloy prepared by SLM technology has a yield strength of 648 MPa and a fracture elongation of 3.9%. 225 (2022).) The Ti-41Nb prepared by SLM technology has a yield strength as high as 814 MPa and a fracture elongation of only 1.3% (laser power of 390 W, scanning speed of 500 mm / s, scanning spacing of 20 μm, and density of 99.8%). It is well known that powder pre-alloying can improve the comprehensive mechanical properties of alloys.In the study by Wang et al. (Q.Wang, C.Han, T.Choma, Q.Wei, C.Yan, B.Song, Y.Shi, Effect of Nb content on microstructure, property and in vitro apatite-forming capability of Ti-Nballoys fabricated via selective laser melting, Materials & Design 126(2017)268-277.), Ti and Nb powders of Ti-15, 25 and 45 at.%Nb were mechanically alloyed using ball milling and processed by SLM (laser power 330W, scanning speed 1000mm / s, scanning spacing 100μm, powder layer thickness 30μm, density 98.7%). The Ti-25Nb alloy showed good tensile properties (yield strength: 516MPa, elongation at break: 24.2%), but the increase in elongation was accompanied by a decrease in yield strength. At the same time, the ball milling process was time-consuming and labor-intensive, which greatly reduced the production efficiency. Meanwhile, most of these studies use spherical Ti powder and irregular Nb powder for SLM processing, which may negatively affect the powder's flowability and uniformity during the SLM process, leading to deterioration of mechanical properties. Therefore, most SLM-processed Ti-Nb alloys exhibit brittleness. Furthermore, pre-alloyed powders are expensive, and different alloy powder compositions require custom manufacturing, resulting in long powder preparation cycles. Therefore, using a mixture of spherical Ti powder and spherical Nb powder for printing can achieve both uniform elemental distribution and compositional freedom, while also significantly reducing processing costs. Summary of the Invention

[0005] This invention provides a high-strength and high-toughness Ti-Nb alloy material rich in nitrogen, with excellent mechanical properties, low modulus, and biocompatibility.

[0006] This invention provides a low-cost method for preparing nitrogen-rich, high-strength and high-toughness Ti-Nb alloys.

[0007] This invention discloses a nitrogen-rich, high-strength, and high-toughness Ti-Nb alloy; the Nitrogen-rich, high-strength, and high-toughness Ti-Nb alloy comprises Ti, Nb, and N; wherein the atomic percentage of Nb is greater than 20 at.% and less than 30 at.%, preferably 22 at.% to 26 at.%, more preferably 24 at.% to 26 at.%, and even more preferably 25 at.%; the mass percentage of N is 0.01 wt.% to 0.5 wt.%, preferably 0.01 wt.% to 0.15 wt.%, and even more preferably 0.05 wt.% to 0.085 wt.%; the density of the Ti-Nb alloy is 99.8%.

[0008] As a preferred embodiment, the present invention provides a nitrogen-rich, high-strength and high-toughness Ti-Nb alloy with an N content of 0.05 wt.% to 0.06 wt.%, more preferably 0.054 wt.%.

[0009] This invention relates to a nitrogen-rich, high-strength, and high-toughness Ti-Nb alloy; the nitrogen-rich, high-strength, and high-toughness Ti-Nb alloy is mainly composed of Ti, Nb, and N.

[0010] This invention discloses a nitrogen-rich, high-strength and high-toughness Ti-Nb alloy. When the Nb content is 25 at.%, the 3D printed product obtained by 3D printing has an ultimate tensile strength of 735-779 MPa, a yield strength of 645-695 MPa, a fracture elongation of 12.5-26.0%, and an elastic modulus of 81.5-85.5 GPa.

[0011] This invention discloses a method for preparing a nitrogen-rich, high-strength, and high-toughness Ti-Nb alloy, comprising the following steps:

[0012] Step 1

[0013] The raw material powder is mixed in a mixer according to the designed composition. The entire mixing process is carried out in a protective atmosphere containing nitrogen to obtain 3D printing powder.

[0014] Step Two

[0015] Using 3D printing powder as the target, selective laser melting technology is used to print the powder layer by layer. The laser power is 180-220W, the scanning speed is 300-800mm / s, the scanning spacing is 80-120μm, the powder layer thickness is 25-45μm, and the scanning strategy is that each layer is tilted at an angle of 67° to the previous layer; the final product is obtained.

[0016] As a preferred embodiment, the present invention provides a method for preparing a nitrogen-rich, high-strength, and tough Ti-Nb alloy, wherein the particle size of the 3D printing spare powder is 15–53 μm.

[0017] As a preferred embodiment, the present invention provides a method for preparing a nitrogen-rich, high-strength and tough Ti-Nb alloy, wherein the particle size of the raw material powder is 15-53 μm, and the raw material powder includes at least two of spherical Ti powder, spherical Nb powder, and spherical Ti-Nb powder.

[0018] In this invention, the mixing time is generally selected to be more than 12 hours, preferably 20 to 28 hours. The nitrogen content adsorbed by the powder is controlled by controlling the nitrogen content in the mixing atmosphere and the mixing time, and then combined with subsequent printing process parameters to keep the nitrogen within a reasonable range.

[0019] In this invention, the protective atmosphere containing nitrogen is composed of argon and nitrogen. As a further preferred embodiment, the volume ratio of nitrogen to argon is 1-2:1-2, and even more preferably 1:1.

[0020] As a preferred embodiment, the present invention provides a method for preparing a nitrogen-rich, high-strength, and tough Ti-Nb alloy. Using 3D printing powder as the object, the powder is printed layer by layer through selective laser melting technology. The laser power is 190–210 W, the scanning speed is 500–700 mm / s, the scanning spacing is 100 μm, the powder layer thickness is 30 μm, and the scanning strategy is that each layer is tilted at an angle of 67° to the previous layer; the final product is obtained.

[0021] As a further preferred embodiment, the present invention provides a method for preparing a nitrogen-rich, high-strength and tough Ti-Nb alloy, using 3D printing powder as the object, and selectively laser melting technology to print the powder layer by layer, with a laser power of 200W and a scanning speed of 700mm / s.

[0022] As a further preferred embodiment, the present invention provides a method for preparing a nitrogen-rich, high-strength and high-toughness Ti-Nb alloy.

[0023] Spherical pure Ti powder with a particle size of 15–53 μm and spherical Nb powder with a particle size of 15–53 μm were mixed at an atomic ratio of 3:1 in a V-type mixer for 24 hours and then set aside. The entire powder mixing process was carried out under a protective gas consisting of 50% argon and 50% nitrogen. Selective laser melting equipment was used to scan the powder layer by layer. The oxygen content in the equipment chamber was not higher than 300 ppm, the laser power was 200 W, the scanning speed was 700 mm / s, the scanning interval was 100 μm, and the powder layer thickness was 30 μm. The resulting 3D printed product had an ultimate tensile strength of 735 MPa, a yield strength of 648 MPa, an elongation at break of 26.0%, and an elastic modulus of 85.1 GPa.

[0024] The nitrogen-rich, high-strength, and high-toughness Ti-Nb alloy designed and prepared in this invention does not produce cytotoxicity.

[0025] This invention relates to an application of a nitrogen-rich, high-strength, and high-toughness Ti-Nb alloy, including its use as an orthopedic implant material. The nitrogen-rich, high-strength, and high-toughness Ti-Nb alloy designed and prepared according to this invention does not exhibit cytotoxicity when used as an orthopedic implant material.

[0026] Principles and advantages

[0027] This invention is the first attempt to introduce an appropriate amount of nitrogen during the mixing process, along with appropriate amounts of Ti and Nb, and with the synergistic effect of the 3D printing process, to obtain a 3D printed product with a yield strength greater than 600 MPa and an elongation greater than 12%. After optimization, the yield strength of the product can be greater than 640 MPa and the elongation at break can be greater than 25%. Attached Figure Description

[0028] Appendix Figure 1 The images show the morphology and particle size distribution of the mixed Ti and Nb spherical powders from Examples 1, 2, and 3. Figure 1 In the figure, (a) is the morphology of Ti-Nb powder after mixing, (b) is the elemental distribution of Ti-Nb powder, (c) is the elemental content diagram, and (d) is the particle size characterization diagram of alloy powder.

[0029] Appendix Figure 2 The molten pool cross-sectional morphology of the products obtained in Examples 1, 2, and 3; Figure 2 (a) and (d) are surface topography images of samples with a vertical scanning speed of 300 mm / s; (b) and (e) are cross-sectional topography images of the molten pool of samples with a scanning speed of 500 mm / s; and (c) and (f) are surface topography images of samples with a scanning speed of 700 mm / s.

[0030] Appendix Figure 3 The images show the XRD characterization patterns of the products obtained in Examples 1, 2, and 3, as well as spherical Ti powder, spherical Nb powder, and Ti-Nb mixed powder.

[0031] Appendix Figure 4 The horizontal molten pool morphology of the products obtained in Examples 1, 2, and 3; Figure 4 In the image, (a) shows the morphology of the molten pool in the horizontal direction when the scanning speed is 300 mm / s, (b) shows the morphology of the molten pool in the horizontal direction when the scanning speed is 500 mm / s, and (c) shows the morphology of the molten pool in the horizontal direction when the scanning speed is 700 mm / s.

[0032] Appendix Figure 5 The microstructure and elemental distribution of the products obtained in Examples 1, 2, and 3 are shown. Figure 5 In the diagram, (a), (d), and (g) are the microstructure and elemental distribution diagrams of the product obtained at a scanning speed of 300 mm / s; (b), (e), and (h) are the microstructure and elemental distribution diagrams of the product obtained at a scanning speed of 500 mm / s; and (c), (f), and (i) are the microstructure and elemental distribution diagrams of the product obtained at a scanning speed of 700 mm / s.

[0033] Appendix Figure 6 The tensile stress-strain curves of the products obtained in Examples 1, 2, and 3 are shown.

[0034] Appendix Figure 7 Quantitative and qualitative characterization of the cytotoxicity of the product obtained in Example 3 and pure Ti; Figure 7 In the figure, (a) shows the OD values ​​of CCK-8 cytotoxicity of CP-Ti and the product obtained in Example 3 against MC3T3-E1 cells, and (b) shows the live and dead fluorescence staining pattern.

[0035] Appendix Figure 8The image shows the molded part obtained in Comparative Example 1. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will now be described in further detail with reference to the accompanying drawings.

[0037] Example 1

[0038] Spherical pure Ti powder (particle size: 15–53 μm) and spherical Nb powder (particle size: 15–53 μm) were mixed uniformly in a V-type mixer at an atomic ratio of 3:1 (Ti: 75 at.%), and then set aside for use. The entire powder mixing process was carried out under the protection of 50% pure argon gas (i.e., 50v% argon + 50v% nitrogen). Selective laser melting (SLM, FARSOON 271M) was used to scan the powder layer by layer (oxygen content in the equipment chamber not exceeding 300 ppm), with a laser power of 200 W, a scanning speed of 300 mm / s, a scanning interval of 100 μm, and a powder layer thickness of 30 μm. Finally, a tensile part with a thickness of 12 mm was prepared. Subsequently, multiple tensile specimens and sheet specimens were cut for subsequent microstructure and mechanical property analysis.

[0039] Implementation effect

[0040] 1. From Figure 1 The spherical alloy powder was observed to be uniformly distributed, indicating good flowability and uniformity. Its density was measured to be 96.2% using the Archimedes displacement method. The surface morphology of the formed block is as follows. Figure 2 As shown in Figure a, observation revealed some holes in the molten pool (indicated by the arrows).

[0041] 2. Figure 3 The XRD patterns of powder and alloy samples with a scanning speed of 300 mm / s are shown. After mixing, the powder did not undergo a phase transformation and remained in the α+β phase. After additive manufacturing, the sample only showed the β phase, with Ti and Nb in infinite solid solution. Therefore, the high temperature generated by the laser during the processing caused Ti and Nb to form a TiNb solid solution of the BCC phase.

[0042] 3. The N content of the alloy sample was determined by scanning at a speed of 300 mm / s, and the N content was 0.130 wt.%.

[0043] 4. Figure 4 Image a shows the morphology characterization of the alloy sample with a horizontal scanning speed of 300 mm / s. Most of the Nb was dissolved with Ti at high temperature, and a small amount of unmelted Nb particles were still distributed in the molten pool. The Ti and Nb contents were 71.5 wt% and 28.5 wt%, respectively. Due to the presence of some unmelted Nb particles, the Nb content in the solution region was less than the nominal Nb content.

[0044] 5. Figure 5 a shows the microstructure of the alloy sample scanned at a horizontal scanning speed of 300 mm / s. The width of the molten pool is approximately 120 μm, which is greater than the set scanning interval of 100 μm. Dendritic β grains are distributed in the molten pool. Figure 5 g shows the elemental distribution and content of Ti and Nb in the solid solution region. The surface shows Nb-depleted and Nb-rich regions, with acicular martensite α' phase forming in the Ti-rich regions (red).

[0045] 6. Table 1 shows the tensile properties of the samples ( Figure 6 Due to the higher residual stress and excessive nitrogen content during the forming process, some plasticity was sacrificed while solid solution strengthening was achieved. Therefore, the sample with a scanning speed of 300 mm / s exhibited brittleness. The elastic modulus of the sample was found to be 76.0 GPa by ultrasonic measurement.

[0046] Table 1. Ultimate tensile strength, yield strength, elongation, and elastic modulus of samples at a scanning speed of 300 mm / s.

[0047]

[0048] Example 2

[0049] Spherical pure Ti powder (particle size: 15–53 μm) and spherical Nb powder (particle size: 15–53 μm) were mixed uniformly in a V-type mixer at an atomic ratio of 3:1 (Ti: 75 at.%), and then set aside for use. The entire powder mixing process was carried out under the protection of 50% pure argon gas (i.e., 50v% argon + 50v% nitrogen). Selective laser melting (SLM, FARSOON 271M) was used to scan the powder layer by layer (oxygen content in the equipment chamber not exceeding 300 ppm), with a laser power of 200 W, a scanning speed of 500 mm / s, a scanning interval of 100 μm, and a powder layer thickness of 30 μm. Finally, a tensile part with a thickness of 12 mm was prepared. Subsequently, multiple tensile specimens and sheet specimens were cut for subsequent microstructure and mechanical property analysis.

[0050] Implementation effect

[0051] 1. The sample density at a scanning speed of 500 mm / s, measured by the Archimedes displacement method, was 98.7%. The surface morphology of the sample is as follows: Figure 2 As shown in b, observation revealed a small number of holes in the molten pool (indicated by the arrow). Compared to Example 1, the holes were more dispersed and smaller in area.

[0052] 2. Figure 3XRD patterns of powder and alloy samples scanned at 500 mm / s are shown. Even after additive manufacturing, the samples still only show the β phase. However, it is noteworthy that compared to the XRD of Example 1, the peak near 40° is shifted to the right. According to Bragg's law, this indicates lattice shrinkage.

[0053] Nb, which has an atomic radius larger than Ti, continuously dissolves from the TiNb solid solution, causing the XRD peak to shift to the right.

[0054] 3. The N content of the alloy sample was detected at a scanning speed of 500 mm / s. The N content was 0.083 wt.%, which was lower than that of Example 1.

[0055] 4. Figure 4 b shows the vertical morphology of the sample. Some Nb dissolved with Ti at high temperature, and some unmelted Nb particles are still distributed in the molten pool.

[0056] 5. Figure 5 b shows the horizontal microstructure of the sample, with a molten pool width of approximately 100 μm, consistent with the set scanning interval. Dendritic β-grains are distributed within the molten pool. Figure 5 h shows the elemental distribution and content of Ti and Nb in the solution region, which are 77.3 wt.% and 22.7 wt.%, respectively, indicating that there are more unmelted Nb particles compared to Example 1, and therefore Nb is reduced in the TiNb solution region.

[0057] 6. Table 2 shows the tensile properties and elastic modulus of the samples. Compared with Example 1, due to less residual stress during the forming process and a relatively lower N content, the solid solution strengthening of N maintained some plasticity, thus the sample exhibited good mechanical properties. Figure 6 The elastic modulus of the sample was determined to be 81.8 GPa by ultrasonic measurement.

[0058] Table 2. Ultimate tensile strength, yield strength, elongation, and elastic modulus of samples with a scanning speed of 500 mm / s.

[0059]

[0060] Example 3

[0061] Spherical pure Ti powder (particle size: 15–53 μm) and spherical Nb powder (particle size: 15–53 μm) were mixed uniformly in a V-type mixer at an atomic ratio of 3:1 (Ti: 75 at.%), and then set aside for use. The entire powder mixing process was carried out under the protection of 50% pure argon gas (i.e., 50v% argon + 50v% nitrogen). Selective laser melting (SLM, FARSOON 271M) was used to scan the powder layer by layer (oxygen content in the equipment chamber not exceeding 300 ppm), with a laser power of 200 W, a scanning speed of 700 mm / s, a scanning interval of 100 μm, and a powder layer thickness of 30 μm. Finally, a tensile part with a thickness of 12 mm was prepared. Subsequently, multiple tensile specimens and sheet specimens were cut for subsequent microstructure and mechanical property analysis.

[0062] Implementation effect

[0063] 1. The sample density measured by Archimedes' displacement method at a scanning speed of 700 mm / s was 99.6%, close to that of a fully dense sample. The surface morphology of the formed sample is as follows: Figure 2 As shown in c, observation revealed that there were almost no pores in the molten pool. Compared with Examples 1 and 2, the pore distribution was minimal and the area was the smallest.

[0064] 2. Figure 3 XRD patterns of powder and alloy samples scanned at 700 mm / s are shown. Even after additive manufacturing, the samples only show a single β phase. However, it is noteworthy that the peak near 40° is shifted to the right more than that of Examples 1 and 2. This indicates that more Nb with atomic radii larger than Ti is continuously dissolving from the TiNb solid solution, resulting in the rightward shift of the XRD peak.

[0065] 3. The nitrogen content of the alloy sample scanned at 700 mm / s was determined to be 0.054 wt.%, which is lower than that in Examples 1 and 2. This change in nitrogen content is due to the formation of a heat-affected zone (HAZ) when the laser remains on the sample, where nitriding occurs. As the scanning speed increases, both the temperature and area of ​​the HAZ decrease. A longer area in the high-temperature region and a longer laser dwell time result in a more complete nitriding reaction.

[0066] 4. Figure 4 c shows the vertical morphology of the sample. A small amount of Nb dissolved with Ti at high temperature, and a large number of unmelted Nb particles were still distributed in the molten pool.

[0067] 5. Figure 5 c shows the horizontal microstructure of the sample, with a melt pool width of approximately 100 μm, consistent with the set scanning interval. Figure 5 i shows the elemental distribution and content of Ti and Nb in the solid solution region, respectively.

[0068] The percentages of 83.0 wt.% and 17.0 wt.% indicate that unmelted Nb particles were most abundant compared to Examples 1 and 2, resulting in a reduction of Nb in the TiNb solid solution region. This region contains both Nb-depleted and Nb-rich areas, while acicular martensite α' phase forms in the Ti-rich region (red).

[0069] 6. Table 3 shows the tensile properties and elastic modulus of the sample. Compared with Examples 1 and 2, this sample exhibits good mechanical properties with a strong-plastic bond due to less residual stress during the forming process and a relatively lower nitrogen content. Figure 6 The elastic modulus of the sample was determined to be 81.8 GPa by ultrasonic measurement.

[0070] 7. Figure 7 The results show the CCK-8 cytotoxicity and live / dead fluorescence staining of CP-Ti and this sample on MC3T3-E1 cells on days 1, 3, and 5. Quantitative analysis of the absorbance (OD) values ​​of CCK-8 showed no significant difference between the Ti-Nb alloy and CP-Ti. Since CP-Ti exhibits good biocompatibility and no cytotoxicity, the same applies to this sample, which also shows good biocompatibility and does not exhibit cytotoxicity. The live / dead fluorescence staining images show cell proliferation over time, with a significant increase in MC3T3-E1 cell numbers on day 5, corresponding to the CCK-8 results.

[0071] Table 3. Ultimate tensile strength, yield strength, elongation, and elastic modulus of samples with a scanning speed of 700 mm / s.

[0072]

[0073] Example 4

[0074] Other conditions were the same as in Example 2, except that spherical pure Ti powder (particle size: 15-53 μm) and spherical Nb powder (particle size: 15-53 μm) were mixed evenly in a V-type mixer at an atomic ratio of 7:3 (Ti: 70 at.%), Nb: 30 at.%) for 24 hours before use.

[0075] Implementation effect

[0076] 1. Due to the introduction of 50v% argon and 50v% nitrogen during the powder mixing process, the sample density was measured to be 96.6% by Archimedes' displacement method.

[0077] 2. Compared to Example 2, the printing process involved a higher concentration of Nb, resulting in more unmelted Nb particles and fewer TiNb solid solution regions in the sample. Consequently, the contribution of solid solution strengthening was smaller. The mechanical properties of the prepared sample are shown in Table 10. The ultimate tensile strength and yield strength of the sample were significantly lower than those of Example 2, while the elongation was slightly higher. The comparison between Example 2 and Example 4 demonstrates that increasing the Nb content does not necessarily guarantee superior performance.

[0078] Table 4. Ultimate tensile strength, yield strength, and elongation of the samples.

[0079] Ultimate tensile strength (MPa) Yield strength (MPa) Elongation at break (%) 650 564 13.9

[0080] Comparative Example 1

[0081] Other conditions remain the same as in Example 1, except that the entire powder mixing process is carried out in air.

[0082] Implementation effect

[0083] like Figure 8 As shown, under these preparation conditions, the sample surface exhibited obvious peeling, delamination, warping, and cracks. Its surface roughness was high, and its forming quality was poor, making subsequent performance testing impossible; therefore, it was a defective product.

[0084] The failure of this batch to form was due to excessive O and N content during the powder mixing process, with the measured O content being 0.4 wt.% and the N content being 0.8 wt.%.

[0085] Comparative Example 2

[0086] Other conditions remained the same as in Example 1, except that the entire powder mixing process was carried out under argon gas with a purity of 99.9%.

[0087] Implementation effect

[0088] Because the powder mixing process is filled with high-purity argon gas, and the forming chamber is filled with pure argon gas during processing, and no nitrogen element is introduced, the measured N content in the sample is only 0.001 wt.%, and the formed sample has good formability.

[0089] The mechanical properties of the prepared samples are shown in Table 5. It can be seen that the elongation of the samples is much higher than that of Example 1, but the ultimate tensile strength and yield strength are much lower than those of Example 1.

[0090] Table 5 Ultimate tensile strength, yield strength, and elongation of samples at a scanning speed of 300 mm / s

[0091] Scan speed Ultimate tensile strength (MPa) Yield strength (MPa) Elongation at break (%) 300mm / s 654 587 11.3

[0092] Comparative Example 3

[0093] Other conditions remained the same as in Example 2, except that the entire powder mixing process was carried out under argon gas with a purity of 99.9%.

[0094] Implementation effect

[0095] 1. Since the powder mixing process is filled with high-purity argon gas and the forming chamber is filled with pure argon gas during the processing, no nitrogen element is introduced. The measured N content in the sample is only 0.001 wt.%, and the prepared sample has good formability.

[0096] 2. The mechanical properties of the prepared samples are shown in Table 6. It can be seen that although the elongation of the sample is slightly higher than that of the example, its ultimate tensile strength and yield strength are much lower than those of Example 2.

[0097] Table 6. Ultimate tensile strength, yield strength, and elongation of samples with a scanning speed of 500 mm / s.

[0098] Scan speed Ultimate tensile strength (MPa) Yield strength (MPa) Elongation at break (%) 500mm / s 633 579 20.2

[0099] Comparative Example 4

[0100] Other conditions remained the same as in Example 3, except that the entire powder mixing process was carried out under argon gas with a purity of 99.9%.

[0101] Implementation effect

[0102] 1. Since the powder mixing process is filled with high-purity argon gas and the forming chamber is filled with pure argon gas during the processing, no nitrogen element is introduced. The measured N content in the sample is only 0.001 wt.%, and the prepared sample has good formability.

[0103] 2. The mechanical properties of the prepared samples are shown in Table 7. It can be seen that the elongation of the samples is slightly lower than that of Example 3, but the ultimate tensile strength and yield strength are much lower than those of Example 3.

[0104] Table 7 Ultimate tensile strength, yield strength, and elongation of samples at a scanning speed of 700 mm / s

[0105] Scan speed Ultimate tensile strength (MPa) Yield strength (MPa) Elongation at break (%) 700mm / s 655 595 24.0

[0106] Comparative Example 5

[0107] All other conditions remain the same as in Example 2, except that the laser power is 300W.

[0108] Implementation effect

[0109] 1. Due to the introduction of 50v% argon and 50v% nitrogen during the powder mixing process, the density of the sample with a laser power of 300W was 97.6% as measured by Archimedes' displacement method.

[0110] 2. Due to the high power of the laser during the printing process, the energy density is increased. The mechanical properties of the prepared sample are shown in Table 8. It can be seen that the ultimate tensile strength and yield strength of the sample are slightly higher than those of Example 2, but its elongation is much lower than that of Example 2.

[0111] Table 8 Ultimate tensile strength, yield strength, and elongation of samples with a laser power of 300W.

[0112] Scan speed Ultimate tensile strength (MPa) Yield strength (MPa) Elongation at break (%) 300W 806 668 8.7

[0113] Comparative Example 6

[0114] All other conditions remain the same as in Example 2, except that the laser power is 400W.

[0115] Implementation effect

[0116] 1. Due to the introduction of 50v% argon and 50v% nitrogen during the powder mixing process, the density of the sample with a laser power of 400W was 96.1% as measured by Archimedes' displacement method.

[0117] 2. Due to the excessive power of the laser during the printing process, the energy density increased. The mechanical properties of the prepared sample are shown in Table 9. It can be seen that the ultimate tensile strength and yield strength of the sample are much higher than those of Example 2 and Comparative Example 5, but its elongation is much lower than that of Example 2.

[0118] Table 9 Ultimate tensile strength, yield strength, and elongation of samples with a laser power of 400W.

[0119] Scan speed Ultimate tensile strength (MPa) Yield strength (MPa) Elongation at break (%) 400W 847 634 7.3

[0120] Comparative Example 7

[0121] Other conditions were the same as in Example 2, except that spherical pure Ti powder (particle size: 15-53 μm) and spherical Nb powder (particle size: 15-53 μm) were mixed evenly in a V-type mixer at an atomic ratio of 4:1 (Ti: 80 at.%), Nb: 20 at.%) for 24 hours before use.

[0122] Implementation effect

[0123] 1. Because 50% argon and 50% nitrogen were introduced during the powder mixing process, the sample density was 98.5% as measured by Archimedes' water displacement method.

[0124] 2. Compared to Example 2, there is less Nb element in the printing process, so there are almost no unmelted Nb particles. The mechanical properties of the prepared sample are shown in Table 10. Since most of Ti and Nb form TiNb solid solution, solid solution strengthening occurs, which easily leads to brittleness. It can be seen that the ultimate tensile strength and yield strength of the sample are higher than those of Example 2, but its elongation is much lower than that of Example 2.

[0125] Table 10 Ultimate tensile strength, yield strength, and elongation of the samples

[0126] Ultimate tensile strength (MPa) Yield strength (MPa) Elongation at break (%) 872 835 2.2

Claims

1. A nitrogen-rich, high-strength, high-toughness Ti-Nb alloy, characterized in that: The nitrogen-rich, high-strength, and high-toughness Ti-Nb alloy comprises Ti, Nb, and N; wherein the atomic percentage of Nb is 22 at.% to 26 at.%, and the mass percentage of N is 0.05 wt.% to 0.085 wt.%; the density of the Ti-Nb alloy is 99.6%. The nitrogen-rich, high-strength, and high-toughness Ti-Nb alloy is prepared through the following steps: Step 1 The raw material powders are mixed in a mixer according to the designed composition. The entire mixing process is carried out in a nitrogen-containing protective atmosphere to obtain 3D printing spare powder. The particle size of the raw material powder is 15~53μm, and the raw material powder includes at least two of the following: spherical Ti powder, spherical Nb powder, and spherical Ti-Nb powder. The particle size of the 3D printing spare powder is 15~53μm. The mixing time is more than 12 hours. The nitrogen-containing protective atmosphere consists of argon and nitrogen. The volume ratio of nitrogen to argon is 1-2:1-2. Step Two Using 3D printing spare powder as the object, selective laser melting technology is used to print the powder layer by layer. The laser power is 190~210W, the scanning speed is 700mm / s, the scanning interval is 100μm, the powder layer thickness is 30μm, and the scanning strategy is that the angle between each layer and the previous layer is 67°; the final product is obtained.

2. The nitrogen-rich, high-strength, and high-toughness Ti-Nb alloy according to claim 1, characterized in that: The atomic percentage of Nb is 24 at.% to 26 at.%.

3. The nitrogen-rich, high-strength, and high-toughness Ti-Nb alloy according to claim 2, characterized in that: The atomic percentage of Nb is 25 at.%.

4. The nitrogen-rich, high-strength, and high-toughness Ti-Nb alloy according to claim 1, characterized in that: The nitrogen content is 0.05 wt.%~0.06 wt.%.

5. The nitrogen-rich, high-strength, and high-toughness Ti-Nb alloy according to claim 4, characterized in that: The nitrogen content is 0.054 wt.%.

6. The nitrogen-rich, high-strength, and high-toughness Ti-Nb alloy according to claim 1, characterized in that: When the Nb content is 25 at.%, the ultimate tensile strength of the 3D printed product obtained by 3D printing is 735~779 MPa, the yield strength is 645~695 MPa, the elongation at break is 12.5~26.0%, and the elastic modulus is 81.5~85.5 GPa.

7. The nitrogen-rich, high-strength, and high-toughness Ti-Nb alloy according to claim 4, characterized in that: The mixing time is 20-28 hours; the protective atmosphere containing nitrogen is composed of argon and nitrogen; the volume ratio of nitrogen to argon is 1:

1.

8. The nitrogen-rich, high-strength, and high-toughness Ti-Nb alloy according to claim 4, characterized in that: Spherical pure Ti powder with a particle size of 15~53μm and spherical Nb powder with a particle size of 15~53μm were mixed in a V-type mixer at an atomic ratio of 3:1 for 24 hours and then set aside. The entire powder mixing process was carried out under a protective gas composed of 50v% argon and 50v% nitrogen. Selective laser melting equipment was used to scan the powder layer by layer. The oxygen content in the equipment chamber was not higher than 300ppm, the laser power was 200W, the scanning speed was 700mm / s, the scanning interval was 100μm, and the powder layer thickness was 30μm. The resulting 3D printed product had an ultimate tensile strength of 735MPa, a yield strength of 648MPa, an elongation at break of 26.0%, and an elastic modulus of 85.1GPa.

9. An application of the nitrogen-rich, high-strength, and high-toughness Ti-Nb alloy as described in any one of claims 1-3, characterized in that: This includes its use as an orthopedic implant material.

Images