A low modulus bioactive ti-nb alloy porous bone implant

Abstract

This invention belongs to the field of biomedical materials and additive manufacturing technology, and discloses a method for preparing and applying a low-modulus bioactive Ti-Nb alloy porous bone implant. The method includes: three-dimensional design of a porous structure; preparation of a Ti-Nb alloy (80~90:10~20) bicrystalline structure preform using a SLM (Sectional Laser Melting) partitioning scanning strategy; activation via a vacuum / inert atmosphere quenching + sandblasting acid-free etching process; and vacuum plasma spraying of a borosilicate bioglass coating. The product contains a Ti-Nb bicrystalline matrix, a three-dimensional through-porous structure, and a borosilicate coating, with a tensile bond strength ≥30MPa. This invention achieves modulus matching with human bone through compositional control, with no toxic precipitation; partitioning scanning constructs a bicrystalline structure to solve Ti-Nb alloy forming defects; the acid-free etching process preserves the mechanical properties of the matrix; and the coating, along with the bicrystalline and porous structure, synergistically achieves high bonding strength and bidirectional osteogenic effects. Simultaneously, the process is simplified, reducing costs by 20-30%, making it suitable for orthopedic spinal fusion implants.

Description

Technical Field

[0001] This invention belongs to the field of biomedical materials and additive manufacturing technology, specifically relating to a low-modulus bioactive Ti-Nb alloy porous bone implant, which is mainly used in the field of hard tissue repair and replacement, such as orthopedic spinal fusion surgery. Background Technology

[0002] Bone implants, as core medical consumables for hard tissue repair and reconstruction in clinical orthopedics, play a crucial role in spinal fusion surgery. Their main types include interlaminar fixation systems, interbody fixation / replacement systems, pedicle screw systems, and interbody fusion cages. These implants typically achieve functions such as segmental spinal fixation, intervertebral space filling, and replacement of diseased vertebrae to treat conditions such as scoliosis, fractures and dislocations, and degenerative disc diseases. Their performance directly affects the success rate of surgery and the long-term rehabilitation outcomes for patients.

[0003] Titanium-based alloys have long dominated the orthopedic implant market due to their excellent mechanical properties and biocompatibility. Among them, Ti-6Al-4V alloy is the most widely used in products such as spinal screws and interbody fusion devices because of its high fatigue strength and good imaging compatibility. However, titanium-based bone implants with Ti-6Al-4V as the base material face three major technological bottlenecks: First, the stress shielding effect. The elastic modulus of Ti-6Al-4V alloy is as high as 110-120 GPa, far exceeding that of human cortical bone (approximately 15-25 GPa). This modulus mismatch causes the implant to bear excessive stress, while the surrounding bone tissue absorbs less stress due to "stress shielding," leading to osteoporosis, implant loosening, and displacement. Clinical studies have shown that the postoperative subsidence rate of Ti-6Al-4V bone implants is as high as 15-30%.

[0004] Second, there is the long-term release of toxic ions. In Ti-6Al-4V alloys, Al and V elements have potential cytotoxicity and neurotoxicity. Although a dense oxide film can form on the surface of bulk materials to inhibit release, the high specific surface area (10-50 times that of bulk materials) of 3D-printed porous structures significantly exacerbates ion release. After long-term implantation, the accumulation of Al and V ions in surrounding tissues may trigger chronic inflammatory responses and even be associated with neurological diseases.

[0005] Third, insufficient osseointegration due to bioinertness. Because titanium alloys are bioinert materials, titanium-based alloys cannot form an effective bond with bone tissue; even if porous structures are formed using 3D printing, the lack of bioactivity induction results in slow bone ingrowth (usually requiring 6-12 months), and the interface is prone to fibrous tissue encapsulation, affecting long-term stability.

[0006] To address the aforementioned issues, Ti-Nb alloys, due to their low elastic modulus (approximately 20-60 GPa) and excellent biocompatibility (Nb is a biocompatible element), have become ideal alternative materials. However, in Ti-Nb alloys, Ti has a melting point of 1668℃, while Nb has a melting point of 2468℃, resulting in a melting point difference of approximately 800℃. When using 3D printing technologies, such as selective laser melting (SLM), compositional inhomogeneity can easily occur. Furthermore, the SLM process window for Ti-Nb alloys is relatively narrow; slight changes in core process parameters such as laser power, scanning speed, thickness, and spacing can lead to part scrap. These core parameters collectively define the appropriate SLM process window. For example, even small changes in laser power and scanning speed can cause significant changes in the type and number of defects, resulting in irregular unfused defects and spherical porosity defects. Therefore, successfully fabricating high-quality products from Ti-Nb alloys using the SLM process is very challenging.

[0007] On the other hand, to address the bioinertness issue of Ti-Nb alloys, existing technologies employ the introduction of bioactive materials, such as bioglass. However, the significant difference in thermal expansion coefficients between Ti-Nb alloys and bioglass coatings can easily lead to residual stress, causing problems such as coating cracking or peeling.

[0008] Furthermore, Nb is an active element, readily forming a dense Nb₂O₅ oxide film on its surface. Traditional acid etching pretreatment is often required before coating the alloy substrate to ensure good adhesion. However, this traditional acid etching pretreatment method, when applied to Ti-Nb alloys, not only leads to deterioration of the substrate's mechanical properties (due to the introduction of O / N / H interstitial elements by the hydrogen evolution reaction), but also makes it difficult to achieve ideal roughness and active site distribution. The coating adhesion strength is typically below 15 MPa, and there is also a risk of peeling.

[0009] In summary, the existing technology lacks a technical solution for titanium-based alloy bone implants that can simultaneously address stress shielding, toxicity release, insufficient osseointegration, and low coating adhesion, which limits the application and expansion of titanium-based alloys in porous bone implants. Summary of the Invention

[0010] This invention addresses the problems of titanium-based alloy bone implants by providing a low-modulus bioactive Ti-Nb alloy porous bone implant. Through material composition control, structural optimization, and synergistic design of the coating system, it solves the stress shielding and toxicity release problems of existing Ti-6Al-4V alloys. This implant achieves an elastic modulus matching that of human cortical bone, exhibits no toxic ion release, and has high coating bonding strength. The porous structure and bioactive coating work synergistically to achieve rapid osseointegration, meeting the reliability requirements for long-term clinical implantation. Another objective of this invention is to provide a method for preparing this implant, using SLM technology with a partitioned scanning strategy to form a bicrystalline structure in a Ti-Nb alloy matrix.

[0011] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: A low-modulus bioactive Ti-Nb alloy porous bone implant comprises a Ti-Nb alloy matrix, a three-dimensional through-porous structure, and a borosilicate bioactive glass coating. The Ti-Nb alloy matrix has a bicrystalline structure, comprising a nanocrystalline region on the surface and a microcrystalline region on the interior. The nanocrystalline region is located from the surface of the Ti-Nb alloy matrix to a depth of 50 μm to 200 μm, and the microcrystalline region is located below the nanocrystalline region to the center of the Ti-Nb alloy matrix. The average grain size of the nanocrystalline region is 100 nm to 900 nm, and the average grain size of the microcrystalline region is 5 μm to 100 μm. The three-dimensional through-porous structure is located inside the Ti-Nb alloy matrix. The borosilicate bioactive glass coating covers the surface of the Ti-Nb alloy matrix and the inner surface of the three-dimensional through-porous structure. The bicrystalline structure is prepared using SLM technology, specifically including: Using Ti-Nb alloy powder as raw material, the mass ratio of Ti to Nb in the Ti-Nb alloy is (80~90):(20~10); a partitioned scanning strategy is adopted, defining the area within 10% thickness of the outer periphery of the scanned object as the contour region and the non-contour region as the filling region. The filling region of the scanned object adopts a first process parameter, and the contour region adopts a second process parameter. Through the partitioned scanning strategy, a bicrystalline structure is formed on the surface of the billet, forming the nanocrystalline region and the microcrystalline region inside. The first process parameter includes: laser power 100W~300W, scanning speed 100mm / s~1500mm / s, scanning gap 0.05mm~0.15mm, strip scanning strategy, and the strip width is 80~120 times the scanning gap; the second process parameter includes: laser power 150W~350W, scanning speed 800mm / s~3000mm / s, and S-shaped linear scanning strategy.

[0012] This invention also provides a method for preparing a low-modulus bioactive Ti-Nb alloy porous bone implant, comprising the following steps: S1: Porous structure design: The bone implant model is divided into a solid frame and an internal filling part using 3D design software. A 3D through-porous structure is designed for the internal filling part to obtain a 3D model of the porous bone implant. S2: SLM forming: Ti-Nb alloy powder is selected as the raw material, and the mass ratio of Ti to Nb in the Ti-Nb alloy is (80~90):(20~10); preferably (83~88):(17~12); a blank is prepared by SLM technology with a partitioned scanning strategy. The area within 10% of the thickness of the scanned object is defined as the contour area, and the non-contour area is the filling area. The filling area of ​​the scanned object is treated with a first process parameter, and the contour area is treated with a second process parameter. Through the partitioned scanning strategy, nanocrystalline regions are formed on the surface of the blank, and microcrystalline regions are formed inside. The crystalline region has a bicrystalline structure, wherein the average grain size of the nanocrystalline region is 100nm~900nm, and the average grain size of the microcrystalline region is 5μm~100μm; the first process parameters include: laser power 100W~300W, scanning speed 100mm / s~1500mm / s, scanning gap 0.05mm~0.15mm, strip scanning strategy, and the strip width is 80~120 times the scanning gap; the second process parameters include: laser power 150W~350W, scanning speed 800mm / s~3000mm / s, and S-shaped linear scanning strategy; S3: Acid-free surface activation treatment: The blank is quenched in a vacuum or inert atmosphere; then the blank is sandblasted, cleaned and dried; S4: Plasma spray coating: A borosilicate bioactive glass coating is prepared on the surface of the blank using vacuum plasma spraying technology to obtain a low-modulus bioactive Ti-Nb alloy porous bone implant.

[0013] Beneficial effects First, this invention achieves a match between the elastic modulus of the implant and that of human cortical bone through precise control of the Ti-Nb alloy composition, while completely eliminating the risk of toxic ion release. This invention limits the mass ratio of Ti to Nb in the Ti-Nb alloy to 80-90:10-20. Within this ratio range, Nb atoms can uniformly dissolve into the Ti matrix, forming a solid solution structure. This reduces the elastic modulus of the implant to 15-45 GPa, highly matching the modulus of human cortical bone and significantly reducing the stress shielding effect. Simultaneously, this alloy does not contain toxic elements such as Al and V, and Nb is a biocompatible element. Even with its porous structure and high specific surface area, there is no risk of toxic ion release, fundamentally avoiding the occurrence of chronic inflammation and neurological complications. Therefore, this invention employs a precise control of the Ti-Nb alloy composition and a zoned differentiated heat input control strategy to solve the stress shielding problem. If the Nb content is less than 10%, fewer Nb atoms dissolve into the matrix, resulting in lower strength and failing to meet the mechanical strength requirements of the implant. If the Nb content is greater than 20%, the amount of Nb dissolved exceeds the capacity of the matrix, leading to compositional segregation, which causes abnormal increases in local modulus and anisotropy in strength. Based on the above, this invention uses a zoned scanning strategy to control differentiated heat input, enabling Nb atoms to uniformly dissolve in the Ti matrix during rapid solidification, avoiding compositional segregation and achieving excellent strength and toughness matching.

[0014] Secondly, this invention constructs a bicrystalline structure of surface nanocrystals and internal microcrystals through a SLM (Sequencing and Laser Processing) partitioning scanning strategy. By actively designing the surface nanocrystal-internal microcrystal bicrystalline gradient structure based on non-equilibrium solidification theory, it solves the problems of compositional inhomogeneity and defects in Ti-Nb alloy SLM forming, while simultaneously improving the mechanical properties of the matrix. This invention addresses the melting point difference between Ti and Nb by employing differentiated SLM process parameters for the filled and contour regions. The low energy density heat input in the filled region ensures a density >99.5% within the matrix, while the formation of microcrystals guarantees the matrix's mechanical support. The high energy density and extremely fast cooling rate in the contour region inhibit grain growth, forming a nanocrystalline structure. Furthermore, rapid heating and cooling achieve uniform solid solution of Nb atoms in the Ti matrix, avoiding forming defects such as compositional segregation, incomplete fusion, and porosity. The solid solution strengthening and grain refinement effects of the bicrystalline structure result in a matrix tensile strength ≥800 MPa and an elongation ≥10%, meeting the mechanical properties required for clinical implantation.

[0015] Furthermore, this invention achieves high bonding strength between the coating and the substrate through the synergistic effect of the bicrystalline structure and the borosilicate coating, solving the problems of coating cracking and peeling. In this invention, the grain boundary density of the nanocrystalline region is approximately 100-1000 times that of the microcrystalline region. This high grain boundary density provides numerous nucleation sites for the semi-molten glass droplets during plasma spraying, increasing surface free energy, enhancing coating wettability, and enabling the coating to form a localized metallurgical bond with the substrate. Combined with the mechanical interlocking formed by sandblasting, this constitutes a composite bonding mode of "grain boundary anchoring + mechanical interlocking + localized metallurgical bonding." This mode results in a tensile bond strength ≥30MPa and a shear bond strength ≥25MPa, which is more than 100% higher than the bonding strength of traditional acid etching-spraying processes, meeting the reliability requirements of coatings for long-term clinical implantation.

[0016] Furthermore, this invention achieves "bidirectional osteogenicity" through the synergistic effect of a three-dimensional through-porous structure and a borosilicate coating, significantly accelerating the osseointegration process. The three-dimensional through-porous structure designed in this invention provides a continuous physical channel for bone tissue to grow into the implant, realizing "bone-to-prosthesis growth"; the borosilicate bioactive glass coating can rapidly degrade in simulated body fluid (SBF), releasing B³⁺. + On the one hand, B³ active ions + It can promote vascularization. On the other hand, after the coating degrades, it will form Ca-P compounds on the implant surface, which will accelerate the formation of the hydroxyapatite (HA) conversion layer and realize "prosthesis to bone growth". The two synergistic bidirectional osteogenic mode can be seen to cross the prosthesis-bone bed gap as early as 4 weeks after surgery. The bone integration rate at 6 weeks is 40% higher than that of traditional products, and there is no fibrous tissue encapsulation phenomenon.

[0017] Furthermore, the preparation method provided by this invention employs an acid-free surface activation process, avoiding the degradation of substrate mechanical properties caused by traditional acid etching, while simultaneously achieving surface roughening and activation. This invention replaces traditional acid etching pretreatment with "vacuum / inert atmosphere quenching + white corundum sandblasting." Quenching eliminates residual stress generated during SLM forming, stabilizes the bicrystalline structure, and prevents excessive grain growth. The mechanical deformation generated by sandblasting introduces high-density dislocations and lattice distortion into the nanocrystalline surface, forming a "mechanically activated layer." Sandblasting also removes the loose oxide layer on the substrate surface, adjusting the surface roughness to Ra0.5-5.0 μm, activating active sites on the nanocrystalline surface, and providing a mechanical interlocking basis for subsequent coating bonding. This process involves no acid, avoiding hydrogen embrittlement caused by hydrogen evolution reaction and lattice contamination by O / N / H interstitial elements, fully preserving the excellent mechanical properties of the SLM-formed parts, while simplifying the process operation.

[0018] In summary, the Ti-Nb alloy porous bone implant of the present invention possesses the core properties of low modulus, non-toxicity, high coating adhesion, and rapid osseointegration. At the same time, the preparation process is simple and low-cost, and the product performance is stable. It has broad clinical application prospects in the field of hard tissue repair such as spinal fusion in orthopedics. Attached Figure Description

[0019] To more clearly illustrate the technical solution of the present invention, the accompanying drawings will be briefly described below. Obviously, the drawings described below only relate to some embodiments of the present invention and are not intended to limit the present invention.

[0020] Figure 1 This is a schematic diagram of a porous bone implant, where 1 is a solid frame and 2 is a porous structure. The solid frame provides mechanical support, and the porous structure provides a channel for bone ingrowth. Figure 2 The image shows the grain structure of the bicrystalline structure, clearly displaying the nanocrystalline region on the surface of the matrix and the microcrystalline region inside. The two are in a gradient transition with no obvious interface. The nanocrystalline region is equiaxed and has a high grain boundary density. Figure 3 Microscopic images of the borosilicate active coating on the trabeculae show that the coating and the substrate interface are free of cracks and pores, and are tightly bonded. Figure 4 The SEM image of the sample surface with the sprayed borosilicate active coating shows that the coating surface is hilly and composed of stacked sheet-like glass particles; Figure 5 This is a tensile / shear bond strength test chart, reflecting the bonding strength between the coating and the substrate. The higher the value, the stronger the coating bonding force. Figure 6 The image shows the surface mineralization after SBF immersion, revealing that the implant surface is completely covered with a hydroxyapatite (HA) deposit layer, reflecting the bioactivity of the coating. Figure 7 This is a fluorescence image of live / dead cells, with green representing live cells and red representing dead cells. A higher percentage of live cells indicates better cell compatibility. Figure 8 This is a graph showing the osteogenic differentiation results of ALP. The higher the absorbance value, the stronger the ability to promote osteogenic differentiation. Detailed Implementation

[0021] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products. In the following embodiments, unless otherwise specified, "%" refers to weight percentage.

[0022] Example 1 A low-modulus bioactive Ti-Nb alloy porous bone implant includes a Ti-Nb alloy matrix, a three-dimensional through-porous structure, and a borosilicate bioactive glass coating. The Ti-Nb alloy matrix has a bicrystalline structure, comprising a nanocrystalline region on the surface and a microcrystalline region on the interior. The nanocrystalline region is located from the surface of the Ti-Nb alloy matrix to a depth of 50 μm to 200 μm, and the microcrystalline region is located below the nanocrystalline region to the center of the Ti-Nb alloy matrix. The three-dimensional through-porous structure is located inside the Ti-Nb alloy matrix. The borosilicate bioactive glass coating covers the surface of the Ti-Nb alloy matrix and the inner surface of the three-dimensional through-porous structure.

[0023] The following describes a method for preparing low-modulus bioactive Ti-Nb alloy porous bone implants, with the following specific steps: S1: Porous Structure Design: A lumbar vertebral implant model was created using 3D design software, with dimensions of length × width × height = 20mm × 5mm × 10mm and a fusion angle of 10° (parallel to the endplate). The model was divided into a solid frame 1 with a wall thickness of 2mm and an internal filling part. A three-dimensional through-hole porous structure 2 of diamond cells was designed for the internal filling part, with the following parameters: pore diameter 700μm, wire diameter 0.1mm, porosity 90%, and cell size 1.5mm × 1.5mm × 1.5mm. The STL file was exported and sliced ​​using 3D printing preprocessing software with a layer thickness of 30μm to obtain the 3D model of the porous bone implant (e.g., ...). Figure 1 ).

[0024] S2: SLM forming: Gas-atomized Ti-Nb alloy powder is selected as raw material, Ti:Nb=85:15 (mass ratio), powder particle size D50=35μm, sphericity>90%, oxygen content<100ppm; SLM forming is performed using a metal 3D printer with a spot diameter of 100μm, Ar2 is used as protective gas, and a partitioned scanning strategy is adopted: the area within 10% thickness of the outer periphery of the scanned object is defined as the contour area, and the non-contour area is the filling area. The filling area of ​​the scanned object adopts the first process parameter, and the contour area adopts the second process parameter. Through the partitioned scanning strategy, a bicrystalline structure is formed on the surface of the blank with a nanocrystalline region and inside with a microcrystalline region.

[0025] It should be noted that the scanning objects of this invention are the solid frame 1 and the porous structure 2 (e.g., Figure 1 As shown), both have contour regions and filled regions. That is, the contour region includes the contour of the solid frame 1 and the outer surface of the porous structure, while the filled region includes the non-contour part of the solid frame 1 and the internal hole structure of the porous structure.

[0026] Specifically: the internal filling region uses a laser with a power of 200W, a scanning speed of 800mm / s, a scanning gap of 0.1mm, and a strip scanning strategy with a strip width of 10mm (100 times the scanning gap). Adjacent strips are in opposite directions to ensure density and form micron-crystals. The contour region uses a laser with a power of 300W, a scanning speed of 2000mm / s, and an S-shaped linear scanning strategy, followed by rapid cooling to form nanocrystals. The resulting Ti-Nb alloy porous bone implant blank has a nanocrystal region on the surface and a micron-crystal region inside.

[0027] S3: Acid-free surface activation treatment: The blank is placed in a vacuum furnace (<10 - The blank was quenched at 550℃ for 2 hours and then water-cooled. The blank was then sandblasted with 100# white corundum gravel at a pressure of 0.5MPa for 60 seconds and an angle of 75°. The blank was then ultrasonically cleaned with deionized water for 15 minutes and dried at 60℃ for later use.

[0028] S4: Plasma spraying coating: Borosilicate bioactive glass powder was selected as the raw material, with a molar composition of B2O3:SiO2:CaO:P2O5=30:15:15:3 and a particle size D50=55μm. The coating was prepared by vacuum plasma spraying technology. The spraying process parameters were: Ar2:H2=70:30 (volume ratio), mixed gas flow rate 100L / min, spraying distance 120mm, spraying current 250A, spray gun scanning speed 100mm / s, blank rotation speed 10rpm, and coating thickness controlled at 100±10μm to obtain a low-modulus bioactive Ti-Nb alloy porous bone implant.

[0029] Performance test results: Testing of the molded low-modulus bioactive Ti-Nb alloy porous bone implant revealed a density of up to 99.7% in the internal filling region of the fusion cage. Figure 2 As shown, the fusion device is free of molding defects such as incomplete fusion and porosity. The matrix has an elastic modulus of 38 GPa, a tensile strength of 850 MPa, and an elongation of 12%. The modulus is highly matched with that of human cortical bone, and the mechanical properties are excellent. The surface nanocrystalline region of the matrix has a high grain boundary density and is equiaxed. The thickness of the nanocrystalline region is about 50 μm and the grain size is 250 ± 50 nm. The internal microcrystalline region has a grain size of 12 ± 3 μm, showing a clear nanocrystalline-microcrystalline bicrystalline structure. like Figure 3 As shown, the interface between the implant coating and the substrate is free of cracks and pores, and the coating is tightly bonded. The coating surface has a hilly and sheet-like overlapping morphology, and the coating thickness is 100±10μm. Coating morphology as Figure 4As shown, the sprayed surface forms a hilly shape, with the surface appearing as sheets stacked together; the tensile bond strength of the coating is 32.7 MPa, and the shear strength is 29.8 MPa. Figure 5 As shown; after immersion in simulated body fluid (SBF) for 7 days, the surface was completely covered with a hydroxyapatite layer, and the mineralization results are as follows. Figure 6 As shown, this demonstrates the excellent bioactivity of the implant. Through MG63 cell culture (e.g. Figure 7 (as shown) and ALP osteogenic differentiation test (as shown) Figure 8 As shown in the figure, the cell viability was 99%, and the ALP differentiation level was significantly higher than that of traditional products, demonstrating excellent cell compatibility and bone regeneration ability.

[0030] Example 2 A low-modulus bioactive Ti-Nb alloy porous bone implant is prepared by the following method: S1: Porous structure design: A lumbar vertebral implant model with the same dimensions as in Example 1 was created using 3D design software. It was divided into a solid frame with a wall thickness of 2mm and an internal filling part. A three-dimensional through-hole porous structure of diamond cells was designed for the internal filling part with the following parameters: pore diameter 200μm, wire diameter 0.2mm, porosity 40%, and cell size 1.0mm×1.0mm×1.0mm. An STL file was exported, and the slice layer thickness was 30μm to obtain the 3D model.

[0031] S2: SLM Molding: Gas-atomized Ti-Nb alloy powder was selected as the raw material, with a Ti:Nb ratio of 90:10 (mass ratio), a powder particle size D50 of 25μm, a sphericity >90%, and an oxygen content <100ppm. SLM molding was performed using a metal 3D printer with a spot diameter of 100μm and Ar2 as the protective gas. The zonal scanning strategy was as follows: the laser power for the internal filling area was 280W, the scanning speed was 1200mm / s, the scanning gap was 0.12mm, and a strip scanning strategy was used with a strip width of 12mm; the laser power for the contour area was 320W, the scanning speed was 2500mm / s, and an S-shaped linear scanning strategy was used. A Ti-Nb alloy porous bone implant blank was thus prepared.

[0032] S3: Acid-free surface activation treatment: The blank is placed in a vacuum furnace for quenching at 500℃ for 2 hours and then water-cooled; it is then sandblasted with 120# white corundum gravel at a pressure of 0.6MPa for 45 seconds and a spray angle of 80°; it is then ultrasonically cleaned with deionized water for 15 minutes and dried at 60℃ for later use.

[0033] S4: Plasma spray coating: Borosilicate bioactive glass powder with a molar composition of B2O3:SiO2:CaO:P2O5=25:18:12:2 and a particle size D50=30μm was selected; Vacuum plasma spraying parameters: Ar2:H2=85:15, mixed gas flow rate 130L / min, spraying distance 140mm, spraying current 220A, spray gun scanning speed 150mm / s, preform rotation speed 8rpm, and coating thickness controlled at 60±5μm to obtain the target implant.

[0034] Performance test results: Testing of the molded target implant revealed that its internal filling area had a density of 99.6%, with no molding defects. The matrix had an elastic modulus of 45 GPa, a tensile strength of 820 MPa, and an elongation of 10%, meeting the mechanical support requirements for clinical implantation. The surface nanocrystalline region was approximately 80 μm thick with a grain size of 150 ± 50 nm, while the internal microcrystalline region had a grain size of 18 ± 5 μm. The bicrystalline structure exhibited a gradient transition without a clear interface. The coating bonded tightly to the matrix without cracks or pores, with a tensile bond strength of 30 MPa and a shear bond strength of 25 MPa, significantly higher than that of traditional acid etching spraying processes. After 7 days of SBF immersion, a uniform and dense HA deposition layer formed on the surface, exhibiting good bioactivity. MG63 cell culture showed 93% viability, excellent ALP differentiation capacity, and cell compatibility and bone regeneration promotion capabilities meeting clinical requirements.

[0035] Example 3 A low-modulus bioactive Ti-Nb alloy porous bone implant is prepared by the following method: S1: Porous structure design: A lumbar vertebral implant model with the same dimensions as in Example 1 was created using 3D design software. It was divided into a solid frame with a wall thickness of 2mm and an internal filling part. A Gyroid minimal surface 3D through-porous structure was designed for the internal filling part with the following parameters: pore diameter 500μm, wire diameter 0.15mm, porosity 75%, and cell size 1.2mm×1.2mm×1.2mm. An STL file was exported, and the slice layer thickness was 30μm to obtain the 3D model.

[0036] S2: SLM molding: The same Ti-Nb alloy powder as in Example 1 (Ti:Nb=85:15, D50=35μm) was selected; the SLM molding parameters were completely consistent with those in Example 1, and a Ti-Nb alloy porous bone implant blank was prepared.

[0037] S3: Acid-free surface activation treatment: The process steps and parameters are completely consistent with those in Example 1.

[0038] S4: Plasma spray coating: The process steps and parameters are completely consistent with those in Example 1, and the target implant is obtained.

[0039] Performance test results: Testing of the molded target implant revealed that its internal filling region had a density of up to 99.7%, with no molding defects. The matrix had an elastic modulus of 36 GPa, a tensile strength of 860 MPa, and an elongation of 13%. The extremely small curved porous structure resulted in a more uniform stress distribution. Under the same porosity, the compressive strength was 15% higher than that of the diamond cell structure, indicating superior mechanical load-bearing performance. The surface nanocrystalline region had a thickness of 50 μm and a grain size of 240 ± 40 nm, while the internal microcrystalline region had a grain size of 11 ± 2 μm and a high density of bicrystalline grain boundaries. The coating had a tensile bond strength of 32 MPa and a shear bond strength of 29 MPa, demonstrating a tight and defect-free bond with the matrix. After 7 days of SBF immersion, the surface was completely covered with a dense HA layer, exhibiting excellent bioactivity. MG63 cell culture showed 98% viability, outstanding ALP differentiation ability, and excellent cell compatibility and bone regeneration promotion capabilities.

[0040] Example 4 A low-modulus bioactive Ti-Nb alloy porous bone implant is prepared by the following method: S1: Porous structure design: A lumbar vertebral implant model with the same dimensions as in Example 1 was created using 3D design software. It was divided into a solid frame with a wall thickness of 2mm and an internal filling part. A three-dimensional through-hole porous structure with Thiessen polygons was designed for the internal filling part with the following parameters: pore diameter 300μm, wire diameter 0.08mm, and porosity 60%. An STL file was exported, and the slices were cut with a layer thickness of 30μm to obtain the 3D model.

[0041] S2: SLM forming: Gas-atomized Ti-Nb alloy powder was selected, with a Ti:Nb ratio of 83:17 (mass ratio), a powder particle size of D50 of 15μm, a sphericity of >90%, and an oxygen content of <100ppm; SLM forming zoned scanning strategy: laser power of 100W, scanning speed of 100mm / s, scanning gap of 0.05mm, and strip width of 4mm (80 times); laser power of 150W, scanning speed of 800mm / s, S-shaped scanning; a blank was prepared.

[0042] S3: Acid-free surface activation treatment: The blank is placed in an Ar inert atmosphere furnace for quenching at 300℃ for 3 hours and then water-cooled; it is then sandblasted with 80# white corundum gravel at a pressure of 0.3MPa for 120 seconds and a spray angle of 60°; it is then ultrasonically cleaned with deionized water for 20 minutes and dried at 60℃.

[0043] S4: Plasma spray coating: Borosilicate bioactive glass powder with a molar composition of B2O3:SiO2:CaO:P2O5=10:20:20:5 and a particle size D50=20μm was selected; Vacuum plasma spraying parameters: Ar2:H2=60:40, mixed gas flow rate 50L / min, spraying distance 80mm, spraying current 200A, spray gun scanning speed 50mm / s, preform rotation speed 5rpm, and coating thickness controlled at 50±5μm to obtain the target implant.

[0044] Performance test results: Testing of the molded target implant revealed that its internal filling area had a density of 99.5%, with no molding defects. The matrix elastic modulus was 25 GPa, which highly matched the modulus of human cortical bone. The tensile strength was 810 MPa, and the elongation was 11%, demonstrating excellent mechanical properties. The surface nanocrystalline region had a thickness of 100 μm and a grain size of 100 ± 30 nm, while the internal microcrystalline region had a grain size of 10 ± 2 μm, exhibiting a stable bicrystalline structure. The coating had a tensile bond strength of 28 MPa and a shear bond strength of 24 MPa, indicating a tight bond with the matrix and no risk of peeling. After 7 days of SBF immersion, a uniform HA deposition layer formed on the surface, exhibiting good bioactivity and effectively inducing bone tissue integration. MG63 cell culture showed 95% viability and good ALP differentiation capacity, with cell compatibility and bone differentiation-promoting ability meeting clinical implantation requirements.

[0045] Example 5 A low-modulus bioactive Ti-Nb alloy porous bone implant is prepared by the following method: S1: Porous structure design: A lumbar vertebral implant model with the same dimensions as in Example 1 was created using 3D design software. It was divided into a solid frame with a wall thickness of 2mm and an internal filling part. A face-centered cubic three-dimensional through-porous structure was designed for the internal filling part with the following parameters: pore diameter 800μm, wire diameter 0.2mm, and porosity 80%. An STL file was exported, and the slices were cut with a layer thickness of 30μm to obtain the three-dimensional model.

[0046] S2: SLM forming: Gas-atomized Ti-Nb alloy powder was selected, with a Ti:Nb ratio of 88:12 (mass ratio), a powder particle size of D50 of 53 μm, a sphericity of >90%, and an oxygen content of <100 ppm; SLM forming zoned scanning strategy: laser power of 300 W, scanning speed of 1500 mm / s, scanning gap of 0.15 mm, and strip width of 18 mm (120 times); laser power of 350 W, scanning speed of 3000 mm / s, S-shaped scanning; a blank was prepared.

[0047] S3: Acid-free surface activation treatment: The blank is placed in a vacuum furnace for quenching at 600℃ for 1 hour and then water-cooled; it is then sandblasted with 100# white corundum gravel at a pressure of 0.8MPa for 30 seconds and a spray angle of 90°; it is then ultrasonically cleaned with deionized water for 10 minutes and dried at 60℃.

[0048] S4: Plasma spray coating: Borosilicate bioactive glass powder with a molar composition of B2O3:SiO2:CaO:P2O5=40:10:10:1 and a particle size D50=90μm was selected; Vacuum plasma spraying parameters: Ar2:H2=90:10, mixed gas flow rate 150L / min, spraying distance 150mm, spraying current 300A, spray gun scanning speed 200mm / s, preform rotation speed 15rpm, and coating thickness controlled at 180±10μm to obtain the target implant.

[0049] Performance test results: Testing of the molded target implant revealed that its internal filling region had a density of up to 99.6%, with no molding defects. The matrix had an elastic modulus of 42 GPa, a tensile strength of 840 MPa, and an elongation of 10%, demonstrating a good balance between modulus matching and mechanical strength. The surface nanocrystalline region had a thickness of 200 μm and a grain size of 300 ± 50 nm, while the internal microcrystalline region had a grain size of 50 ± 5 μm, exhibiting a significant grain boundary anchoring effect in the bicrystalline structure. The coating had a tensile bond strength of 31 MPa and a shear bond strength of 28 MPa, showing a tight bond with the matrix without cracks and good coating uniformity. After 7 days of SBF immersion, the surface was completely covered with a dense HA layer, exhibiting excellent bioactivity and rapid hydroxyapatite deposition. MG63 cell culture showed a viability of 97% and excellent ALP differentiation ability, effectively promoting bone tissue growth and integration.

[0050] Example 6 A low-modulus bioactive Ti-Nb alloy porous bone implant is prepared by the following method: S1: Porous structure design: Completely consistent with Example 1, a diamond cell porous structure is designed with a pore size of 700 μm and a porosity of 90%.

[0051] S2: SLM forming: The same Ti-Nb alloy powder as in Example 1 (Ti:Nb=85:15, D50=35μm) was selected; the partition scanning process parameters were adjusted: laser power of 250W, scanning speed of 1200mm / s, scanning gap of 0.12mm, and strip width of 12mm (100 times); laser power of 300W, scanning speed of 2000mm / s, and S-shaped linear scanning strategy were used to prepare the blank.

[0052] S3: Acid-free surface activation treatment: completely consistent with Example 1.

[0053] S4: Plasma spray coating: exactly the same as in Example 1, to obtain the target implant.

[0054] Performance test results: Testing of the molded target implant revealed that its internal filling region had a density of up to 99.7%, with no molding defects. The matrix had an elastic modulus of 37 GPa, a tensile strength of 855 MPa, and an elongation of 12%, exhibiting stable and excellent mechanical properties. The surface nanocrystalline region had a thickness of 60 μm and a grain size of 260 ± 40 nm, while the internal microcrystalline region had a grain size of 13 ± 3 μm, demonstrating a clear bicrystalline structure and high grain boundary density. The coating exhibited a tensile bond strength of 32 MPa and a shear bond strength of 29 MPa, indicating a tight bond with the matrix and stable coating adhesion. After 7 days of SBF immersion, a dense HA layer completely covered the surface, demonstrating excellent bioactivity and the ability to rapidly form an active interface for bone integration. MG63 cells showed 98% viability in culture, excellent ALP differentiation capacity, and outstanding cell compatibility and bone regeneration promotion capabilities.

[0055] Example 7 A low-modulus bioactive Ti-Nb alloy porous bone implant is prepared by the following method: S1: Porous structure design: completely consistent with Example 1.

[0056] S2: SLM molding: Completely consistent with Example 1, a blank is prepared.

[0057] S3: Acid-free surface activation treatment: Adjust activation process parameters: Place the blank in a vacuum furnace for quenching at 400℃ for 3 hours, then water-cool; use 90# white corundum gravel for sandblasting at a pressure of 0.4MPa for 90s and a spray angle of 70°; ultrasonically clean with deionized water for 15 minutes and dry at 60℃.

[0058] S4: Plasma spray coating: exactly the same as in Example 1, to obtain the target implant.

[0059] Performance test results: Testing of the molded target implant revealed that its internal filling region had a density of 99.7%, with no molding defects. The matrix had an elastic modulus of 38 GPa, a tensile strength of 845 MPa, an elongation of 12%, and no degradation in mechanical properties, remaining intact. The surface nanocrystalline region had a thickness of 55 μm and a grain size of 240 ± 50 nm, while the internal microcrystalline region had a grain size of 12 ± 2 μm. The stability of the bicrystalline structure was improved after quenching. The coating had a tensile bond strength of 31 MPa and a shear bond strength of 28 MPa, indicating a tight bond with the matrix. The surface roughness after sandblasting provided a good mechanical interlocking basis for the coating. After 7 days of SBF immersion, a dense HA layer was fully covered on the surface, exhibiting excellent biological activity and a uniform distribution of active sites. MG63 cells showed 97% viability in culture, excellent ALP differentiation ability, and good cell adhesion and growth.

[0060] Example 8 A low-modulus bioactive Ti-Nb alloy porous bone implant is prepared by the following method: S1: Porous structure design: completely consistent with Example 1.

[0061] S2: SLM molding: Completely consistent with Example 1, a blank is prepared.

[0062] S3: Acid-free surface activation treatment: completely consistent with Example 1.

[0063] S4: Plasma spray coating: The same borosilicate glass powder as in Example 1 was selected; the spraying process parameters were adjusted as follows: Ar2:H2=80:20, mixed gas flow rate 120L / min, spraying distance 100mm, spraying current 280A, spray gun scanning speed 120mm / s, blank rotation speed 12rpm, and coating thickness controlled at 120±10μm to obtain the target implant.

[0064] Performance test results: Testing of the molded target implant revealed that its internal filling region had a density of 99.7%, with no molding defects. The matrix exhibited an elastic modulus of 38 GPa, a tensile strength of 850 MPa, and an elongation of 12%, maintaining stable mechanical properties. The surface nanocrystalline region had a thickness of 50 μm and a grain size of 250 ± 50 nm, while the internal microcrystalline region had a grain size of 12 ± 3 μm, demonstrating a significant grain boundary anchoring effect in the bicrystalline structure. The coating exhibited a tensile bond strength of 33 MPa and a shear bond strength of 30 MPa, showing tight and defect-free bonding with the matrix. The coating thickness was uniform, with no overheating or devitrification. After 7 days of SBF immersion, a dense HA layer fully covered the surface, demonstrating excellent bioactivity and uniform hydroxyapatite deposition. MG63 cell culture showed 99% viability and excellent ALP differentiation capacity, exhibiting optimal cell compatibility and bone regeneration promotion capabilities.

[0065] Comparative Example 1 (Material replacement: Ti-6Al-4V alloy replaces Ti-Nb alloy) This comparative example uses a Ti-6Al-4V alloy instead of the Ti-Nb alloy of the present invention, and the remaining processes are the same as in Example 1, to verify the effect of Ti-Nb alloy composition control on modulus matching and toxic precipitation. The specific steps are as follows: S1: Porous structure design: completely consistent with Example 1.

[0066] S2: SLM forming: Ti-6Al-4V (ELI) powder was selected with D50=35μm; conventional SLM process was adopted with no partition scanning and uniform parameters: laser power 280W, scanning speed 1200mm / s, scanning gap 0.12mm, forming coarse grains (average grain size about 30μm); a green body was prepared.

[0067] S3: Surface treatment: Same as the sandblasting treatment in Example 1.

[0068] S4: Plasma spray coating: completely consistent with Example 1.

[0069] Table 1 Comparison of Product Performance in Comparative Example 1

[0070] Comparative Example 1 uses a traditional Ti-6Al-4V alloy, whose elastic modulus is much higher than that of human cortical bone, resulting in a significant stress shielding effect, a significant decrease in the matching degree between stress distribution and surrounding bone tissue, and a risk of Al and V toxic ion precipitation. The coating bonding strength is also lower than that of Example 1 due to the lack of grain boundary anchoring effect of the bicrystalline structure.

[0071] Conclusion: Compared with Ti-6Al-4V, Ti-Nb alloy can completely eliminate the risk of precipitation of toxic ions such as Al and V, and can adjust the elastic modulus to solve the stress shielding problem.

[0072] Comparative Example 2 (Process replacement, SLM overall scanning replaces partitioned scanning) This comparative example uses SLM with unified parameter scanning to replace the partitioned scanning strategy of the present invention. The remaining processes are completely consistent with those in Example 1. It is used to verify the influence of the partitioned scanning strategy on the construction of the bicrystalline structure and the coating adhesion. The specific steps are as follows: S1: Porous structure design: completely consistent with Example 1.

[0073] S2: SLM forming: The same Ti-Nb alloy powder as in Example 1 (Ti:Nb=85:15) was selected; conventional uniform parameter scanning was used: laser power 250W, scanning speed 800mm / s, no partitioning scanning, to form a uniform grain structure (average grain size about 8μm, no twinning structure); a green body was prepared.

[0074] S3: Acid-free surface activation treatment: completely consistent with Example 1.

[0075] S4: Plasma spray coating: completely consistent with Example 1.

[0076] Table 2 Comparison of Product Performance in Comparative Example 2

[0077] Comparative Example 2, due to its overall scanning process, could not construct a bicrystalline structure. The grain structure consisted of uniform micron-sized grains with low grain boundary density. During plasma spraying, there were few glass droplet nucleation sites, resulting in a weak grain boundary anchoring effect. Consequently, the coating and substrate were primarily mechanically interlocked, significantly reducing the bonding strength. In contrast, the nanocrystalline region of Example 1 provided high-density grain boundaries, forming a composite bonding mode of "grain boundary anchoring + mechanical interlocking + localized metallurgical bonding."

[0078] Conclusion: The bicrystalline structure constructed by the partitioned scanning strategy is the key to achieving high coating adhesion, which is a conventional result of non-SLM processes.

[0079] Comparative Example 3 (Acid etching pretreatment instead of acid-free activation) This comparative example uses traditional acid etching pretreatment instead of the "quenching + sandblasting" acid-free activation process of the present invention. The remaining processes are completely consistent with those in Example 1. This example is used to verify the influence of the acid-free process on the mechanical properties of the substrate and the adhesion of the coating. The specific steps are as follows: S1: Porous structure design: completely consistent with Example 1.

[0080] S2: SLM molding: exactly the same as in Example 1, a bicrystalline structure preform was prepared.

[0081] S3: Acid etching pretreatment: Remove the quenching and sandblasting steps, acid etch the billet with a 10% HF + 30% HNO3 aqueous solution, soak at room temperature for 60 seconds, rinse with deionized water and dry.

[0082] S4: Plasma spray coating: completely consistent with Example 1.

[0083] Table 3 Comparison of Product Performance in Comparative Example 3

[0084] Comparative Example 3 uses traditional acid etching pretreatment. The hydrogen evolution reaction during the acid etching process causes hydrogen atoms to penetrate into the substrate and form hydrogen embrittlement. At the same time, the O / N element solid solution increases, which significantly reduces the mechanical properties of the substrate. Furthermore, the surface roughness is uneven and the distribution of active sites is disordered after acid etching, resulting in a significant reduction in the bonding strength of the coating.

[0085] Conclusion: The acid-free etching process not only simplifies the process, but is also the key to ensuring the mechanical properties and coating reliability of the product. Acid etching pretreatment is not suitable for Ti-Nb alloy SLM formed parts.

[0086] Comparative Example 4 (Plasma Spraying without Optimized Parameters) This comparative example uses unoptimized plasma spraying parameters, while the remaining processes are completely consistent with Example 1, to verify the necessity of optimizing plasma spraying parameters. The specific steps are as follows: S1: Porous structure design: completely consistent with Example 1.

[0087] S2: SLM molding: exactly the same as in Example 1, a bicrystalline structure preform was prepared.

[0088] S3: Acid-free surface activation treatment: completely consistent with Example 1.

[0089] S4: Plasma spray coating: Plasma spraying parameters deviated from the optimized range: Ar2:H2=50:50 (H2 ratio too high), spraying distance 200mm (too far), spraying current 350A (too high); the rest were the same as in Example 1.

[0090] Table 4 Comparison of Product Performance in Comparative Example 4

[0091] Comparative Example 4 was caused by unoptimized plasma spraying parameters, such as excessively high H2 ratio, excessively long spraying distance, and excessively high spraying current, which led to overheating and devitrification of the coating, increased porosity, and a significant decrease in the adhesion between the coating and the substrate. At the same time, the biological activity was also reduced due to the defects in the coating structure.

[0092] Conclusion: Plasma spraying parameters need to be strictly optimized. Unoptimized parameters will lead to overheating, devitrification, high porosity, and a significant decrease in adhesion and bioactivity of the coating.

[0093] Comparative Example 5 (Uncoated Ti-Nb Alloy Porous Fusion Machine) This comparative example omits the plasma spraying coating step; the remaining processes are completely identical to those in Example 1. It is used to verify the necessity of the bioactive coating, and the specific steps are as follows: S1: Porous structure design: completely consistent with Example 1.

[0094] S2: SLM molding: exactly the same as in Example 1, a bicrystalline structure preform was prepared.

[0095] S3: Acid-free surface activation treatment: completely consistent with Example 1.

[0096] S4: No plasma spraying step, directly obtaining an uncoated implant.

[0097] Table 5 Comparison of Product Performance in Comparative Example 5

[0098] Comparative Example 5, lacking a bioactive coating, could not achieve effective bioactive induction solely through its porous structure, resulting in slow bone ingrowth, low bone integration rate, and easy formation of fibrous tissue encapsulation at the interface. In contrast, Example 1 achieved "bidirectional osteoogenesis" through the synergy of a porous structure and a borosilicate coating.

[0099] Conclusion: Bioactive coatings are a necessary condition for achieving rapid osteointegration and work synergistically with porous structures to exert bidirectional osteogenic effects.

[0100] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0101] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0102] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A low-modulus bioactive Ti-Nb alloy porous bone implant, characterized in that, The invention comprises a Ti-Nb alloy substrate, a three-dimensional through-porous structure, and a borosilicate bioactive glass coating. The Ti-Nb alloy substrate has a bicrystalline structure, comprising a nanocrystalline region on the surface and a microcrystalline region on the interior. The nanocrystalline region is located from the surface of the Ti-Nb alloy substrate to a depth of 50 μm to 200 μm, and the microcrystalline region is located below the nanocrystalline region to the center of the Ti-Nb alloy substrate. The average grain size of the nanocrystalline region is 100 nm to 900 nm, and the average grain size of the microcrystalline region is 5 μm to 100 μm. The three-dimensional through-porous structure is located inside the Ti-Nb alloy substrate. The borosilicate bioactive glass coating covers the surface of the Ti-Nb alloy substrate and the inner surface of the three-dimensional through-porous structure. The bicrystalline structure is prepared using SLM technology, specifically including: using Ti-Nb alloy powder as raw material, wherein the mass ratio of Ti to Nb in the Ti-Nb alloy is (80~90):(20~10); employing a partitioned scanning strategy, defining the area within 10% of the thickness of the scanned object as the contour region and the non-contour region as the filling region, then applying a first process parameter to the filling region of the scanned object and a second process parameter to the contour region, thereby forming a bicrystalline structure with the nanocrystalline region on the surface of the blank and the microcrystalline region inside through the partitioned scanning strategy; the first process parameter includes: laser power 100W~300W, scanning speed 100mm / s~1500mm / s, scanning gap 0.05mm~0.15mm, strip scanning strategy, and the strip width being 80~120 times the scanning gap; the second process parameter includes: laser power 150W~350W, scanning speed 800mm / s~3000mm / s, and S-shaped linear scanning strategy.

2. The low-modulus bioactive Ti-Nb alloy porous bone implant according to claim 1, characterized in that, The density of the Ti-Nb alloy matrix is ​​>99.5%, and the tensile strength is ≥800MPa.

3. The low-modulus bioactive Ti-Nb alloy porous bone implant according to claim 2, characterized in that, The elongation of the Ti-Nb alloy matrix is ​​≥10%.

4. The low-modulus bioactive Ti-Nb alloy porous bone implant according to claim 3, characterized in that, The elastic modulus of the Ti-Nb alloy matrix is ​​15-45 GPa.

5. The low-modulus bioactive Ti-Nb alloy porous bone implant according to any one of claims 1-4, characterized in that, The thickness of the borosilicate bioactive glass coating is 50μm~200μm, the tensile bond strength is ≥25MPa, and the shear bond strength is ≥25MPa.

6. The low-modulus bioactive Ti-Nb alloy porous bone implant according to claim 5, characterized in that, The borosilicate bioactive glass coating forms a complete hydroxyapatite deposition layer on its surface after being immersed in simulated body fluid for 7 days. The low-modulus bioactive Ti-Nb alloy porous bone implant forms new bone across the prosthesis-bone bed gap 4 weeks after surgery.

7. A method for preparing a low-modulus bioactive Ti-Nb alloy porous bone implant according to any one of claims 1-6, characterized in that, Includes the following steps: S1: Porous structure design: The bone implant model is divided into a solid frame and an internal filling part using 3D design software. A 3D through-porous structure is designed for the internal filling part to obtain a 3D model of the porous bone implant. S2: SLM forming: Ti-Nb alloy powder is selected as raw material, and the mass ratio of Ti to Nb in the Ti-Nb alloy is (80~90):(20~10); the blank is prepared by SLM technology with a partitioned scanning strategy. The area within 10% thickness of the outer periphery of the scanned object is defined as the contour area, and the non-contour area is the filling area. The filling area of ​​the scanned object is treated with the first process parameter, and the contour area is treated with the second process parameter. Through the partitioned scanning strategy, a bicrystalline structure is formed on the surface of the blank, with a nanocrystalline region and a microcrystalline region inside. The average grain size of the nanocrystalline region is 100nm~900nm, and the average grain size of the microcrystalline region is 5μm~100μm. The first process parameters include: laser power of 100W~300W, scanning speed of 100mm / s~1500mm / s, scanning gap of 0.05mm~0.15mm, strip scanning strategy, and strip width of 80~120 times the scanning gap; the second process parameters include: laser power of 150W~350W, scanning speed of 800mm / s~3000mm / s, and S-shaped linear scanning strategy. S3: Acid-free surface activation treatment: The blank is quenched in a vacuum or inert atmosphere; then the blank is sandblasted, cleaned and dried; S4: Plasma spray coating: A borosilicate bioactive glass coating is prepared on the surface of the blank using vacuum plasma spraying technology to obtain a low-modulus bioactive Ti-Nb alloy porous bone implant.

8. The preparation method according to claim 7, characterized in that, The cell type of the porous structure in step S1 is selected from at least one of diamond cell, Thiessen polygon, minimal surface, and face-centered cubic structure. The pore size of the porous structure is 200μm~900μm, the porosity is 40%~90%, and the wire diameter is 0.05mm~1.0mm.

9. The preparation method according to claim 7, characterized in that, The Ti-Nb alloy powder in step S2 has a particle size D50 of 15 μm to 53 μm and an oxygen content ≤100 ppm; the mass ratio of Ti to Nb in the Ti-Nb alloy is (83~88):(17~12); or, The quenching temperature in step S3 is 300℃~600℃, and the holding time is 1h~3h; the sandblasting pressure is 0.3MPa~0.8MPa, the sandblasting time is 30s~120s, the spraying angle is 60°~90°, and the surface roughness of the obtained blank is Ra=0.5-5.0μm.

10. The preparation method according to any one of claims 7-9, characterized in that, The plasma spray coating in step S4 uses borosilicate bioactive glass powder with a molar composition of B2O3:SiO2:CaO:P2O5=(10~40):(10~20):(10~20):(1~5) and a particle size D50 of 20μm~90μm. The spraying atmosphere is a mixture of Ar2 and H2 with a volume ratio of (60~90):(10~40), a mixed gas flow rate of 50L / min~150L / min, a spraying distance of 80mm~150mm, a spraying current of 200A~300A, a spray gun scanning speed of 50mm / s~200mm / s, and the preform rotates 360° during the spraying process to control the coating thickness to be 50μm~200μm.

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