A bone implant microstructure based on polycrystalline doping mechanical property strengthening

Abstract

This invention discloses a microstructure for bone implants enhanced by polycrystalline doping, comprising a soft-phase cell structure, a hard-phase cell structure, and a soft-hard phase doped structure. The soft-phase core and hard-phase shell are combined, with each cell of the hard-phase shell structure on the outside of the soft-phase core structure having a completely overlapping cross-section with the corresponding circumscribed cube of the soft-phase core structure, forming a face-to-face bond that constructs a soft-hard phase doped structure where the hard-phase shell completely encloses the soft-phase core. The elastic modulus can be effectively increased by 1.5-1.75 times while maintaining a basically identical stress-strain curve shape. Under high porosity, the stress-strain curve of 8.3% hard-phase reinforcement approximates a standard rhombic dodecahedron, except for the increased elastic modulus, the curve is similar to a standard rhombic dodecahedron. The advantage of 50% hard-phase reinforcement is that the composite structure model has better overall mechanical properties. 8.3% hard-phase reinforcement saves approximately 13% of material while maintaining a basically identical stress-strain curve to the control group, while 50% hard-phase reinforcement saves approximately 25% of material.

Description

Technical Field

[0001] This invention belongs to the field of orthopedic medical devices, specifically a microstructure of bone implants based on enhanced mechanical properties through polycrystalline doping. Background Technology

[0002] Most mainstream bone implants employ a lattice structure design, and many are single-lattice designs. Lattice structure parameters significantly influence bone cell inward growth, bone-to-surface integration, and the replacement of bone physical functions. For example, if the elastic modulus of the lattice structure is much higher than that of the surrounding bone tissue, stress shielding will occur around the implant, hindering bone remodeling and regeneration. Similarly, in intervertebral fusion devices, if the yield strength of the lattice structure is much lower than that of the vertebrae, the spinal weight-bearing function cannot be replaced by the implant, leading to lattice collapse. These two points are problems that are difficult to avoid with the single microstructure used in mainstream bone implant designs. Furthermore, a single lattice structure significantly reduces the implant's fatigue and damage resistance, thus highlighting the significant potential and necessity for improvement and optimization in structural design.

[0003] Existing research indicates that the strengthening mechanisms of crystal lattice microstructures can produce similar effects on a macroscopic scale, such as grain boundary hardening, precipitation hardening, and multiphase hardening. Taking hard phase strengthening as an example, the damage resistance mechanism involves the regular interdoping of hard and soft phases, which can limit the propagation of shear bands. In the hard phase, shear bands in the overall structure can be broken, thus preventing localized deformation and damage when subjected to large loads.

[0004] Current mainstream porous bone implant designs suffer from the following problems:

[0005] 1. Traditional porous implants have a relatively simple microstructure, and when the stress exceeds the maximum permissible value, local high-stress zones will appear, which will cause their fatigue resistance to drop sharply.

[0006] 2. The mismatch in overall mechanical properties can lead to severe "stress shielding," causing collapse and absorption of the bone tissue surrounding the implanted device.

[0007] 3. Existing bone implant designs can cause stress concentration at both the microscopic and macroscopic levels. Summary of the Invention

[0008] The purpose of this invention is to optimize the microstructure of bone implants, thereby significantly improving the overall fatigue resistance and load-bearing capacity of bone implants, in order to solve many problems of mainstream porous bone implants.

[0009] The technical solution of this invention is implemented as follows:

[0010] A microstructure for bone implants enhanced by polycrystalline doping is disclosed, comprising a soft-phase cell structure, a hard-phase cell structure, and a soft-hard phase doped structure. The soft-phase core is a blocky structure constructed by mirroring or arraying operations, where the corresponding cross-sections of the circumscribed cubes of each soft-phase cell completely overlap and are face-to-face bonded. The hard-phase shell is a shell-like structure constructed by mirroring or arraying operations, where the corresponding cross-sections of the circumscribed cubes of each hard-phase cell completely overlap and are face-to-face bonded. The bonding between the soft-phase core and the hard-phase shell occurs on the outside of the soft-phase core structure. Each cell of the hard-phase shell structure has a cross-section that completely overlaps with the corresponding circumscribed cube of the soft-phase core structure, forming a soft-hard phase doped structure where the hard-phase shell completely encloses the soft-phase core. The bonding surface between the soft-phase core and the hard-phase shell is the cross-section of the circumscribed cube of each cell. A soft-hard phase doping structure with a soft-hard phase doping ratio of 50% means that the number of soft phase cell structures in an array is 5*5 in a planar dimension, and the hard phase shell is to cover the soft phase core. That is, the number of hard phase cells in the plane is 6*4. Based on this doping structure, various larger-sized soft-hard phase doping structures can be constructed by arraying them in the vertical or horizontal direction.

[0011] The soft phase cell structure adopts a regular rhombic dodecahedral cell structure, with the rhombic dodecahedron inscribed in a cube. The three-dimensional structure of this cell mainly utilizes the diameter d of the pillars to drive the change in cell porosity. The arrangement of the pillar diameters is the edges of the rhombic dodecahedron. The cell pillars are formed by rotating a drawn cross-sectional sketch along the central axis. The hard phase cell structure design is based on the soft phase structure with the addition of a rhombic dodecahedron structure with four reinforcing ribs. These four reinforcing ribs are set along a pair of opposite edges of the cube inscribed by the rhombic dodecahedron cell, which are the four edges extending in the same direction. The so-called soft and hard phase doped structure consists of two parts: a soft phase core and a hard phase shell. The soft phase cell forms the core to improve mechanical properties such as damage resistance. A layer of hard phase cell structure surrounds the soft phase core to form a supporting shell, i.e., the hard phase shell.

[0012] The soft phase cell structure refers to a structure based on a rhombic dodecahedron structure, constructed using solid cylindrical supports of diameter d according to the edge position relationships of the rhombic dodecahedron. The constructed support structure is then inscribed within a cube with side length c. The intersection points of the rhombic dodecahedron are the face centers of each face of the cube. The soft phase cell structure utilizes the diameter d of the cylindrical supports to drive the change in cell porosity. The side length of the cell is c. The specific structural parameters are as follows: the modeling of the rhombic dodecahedron soft phase cell is completed with d = 0.3 mm and c = 2 mm.

[0013] The soft-hard phase doped structure is divided into two parts: a soft phase core and a hard phase shell. Since the soft phase cell structure has no reinforcing ribs, its elastic modulus and compressive strength are lower than those of the hard phase cell structure. Using a stacked array of soft phase cell structures as the core improves the damage resistance and can accommodate plastic deformation. A hard phase shell composed entirely of hard phase cells is wrapped around the soft phase core. Because the hard phase cell structure has a reinforcing rib design, the hard phase shell formed by stacking hard phase cells can provide higher mechanical strength to improve the overall load-bearing capacity of the soft-hard phase doped structure.

[0014] The soft phase core of the soft-hard phase doped structure is formed by the complete overlap of the corresponding cross-section of the outer cube of each soft phase cell, so that each soft phase cell structure is tightly attached to the cross-section of the outer cube, completing the connection between the soft phase cells. Then, according to the soft-hard phase doping ratio, the final overall structure is constructed by mirroring or arraying.

[0015] The outer shell of the soft-hard doped structure is formed by the complete overlap of the corresponding cross-section of the circumscribed cube of each hard phase cell. Each hard phase cell structure is tightly fitted to the cross-section of the circumscribed cube, thus completing the connection between the hard phase cells. Then, based on the size of the soft phase core and the doping ratio of the soft and hard phases, the final overall structure is constructed by mirroring or arraying.

[0016] In the shell of the soft-hard doped structure, the bonding area between hard phase cells is greater than that between soft phase cells. In addition to being tightly fitted at the cross-section of the corresponding circumscribed cube, each cell structure also forms a bonding surface with the cross-section formed by the corresponding reinforcing ribs of the hard phase cell and the circumscribed cube.

[0017] The combination of the soft phase core and hard phase shell of the soft and hard phase doped structure first requires stacking the soft phase core according to the soft and hard phase doping ratio and the final structure size. Then, on the outside of the soft phase core, the corresponding outer cubic cross-sections of the hard phase cell and the soft phase cell are completely overlapped to construct the hard phase shell, which completely encloses the soft phase core. The bonding surface between the soft phase core and the hard phase shell is the cross-section of the outer cubic of each corresponding cell.

[0018] The soft and hard phase doping structure has a soft and hard phase doping ratio of 50%. This structure requires the construction of a basic soft and hard phase doping structure with a total number of 7*7 unit cells in the planar dimension. The soft phase unit cells are inside, with a number of 5*5. The hard phase shell is to cover the periphery of the soft phase core, so the number of hard phase unit cells is 6*4. Based on this doping structure, various larger-sized soft and hard phase doping structures with a soft and hard phase doping ratio of 50% can be constructed.

[0019] This invention selects a porous structure design and optimization scheme based on rhombic dodecahedrons to optimize the microstructure of bone implants with enhanced mechanical properties through polycrystalline doping. By applying crystal strengthening mechanisms to gradually optimize the design, a polycrystalline microstructure with excellent mechanical properties is finally obtained.

[0020] The beneficial effects achieved by this invention are as follows:

[0021] This invention proposes a microstructure for bone implants based on polycrystalline doping to enhance mechanical properties. Single-crystal structures such as concave hexagons, S-shaped hinges, rhombic dodecahedrons, and ribbed rhombic dodecahedrons were constructed and compared through simulation analysis. Modeling of 2mm and 3mm basic bone implants was completed. A polycrystalline structure design method was employed to design a porous structure with soft and hard phase doping for damage resistance. Based on simulation results, different designs were quantitatively analyzed and evaluated. Preliminary experiments verified the comprehensive mechanical properties and damage resistance of the bone implants. Through enhanced design, 8.3% hard phase reinforced and 50% hard phase reinforced bone implant models were finally developed, with elastic moduli increased by 46% and 310%, respectively, and material savings of approximately 13% and 25%, respectively. Under high porosity (80% porosity), the stress-strain curve of the 8.3% hard phase reinforced implant is close to that of a standard rhombic dodecahedron; except for the increased elastic modulus, the curve is similar to that of a standard rhombic dodecahedron. The stress-strain curve of the 50% hard-phase reinforcement conforms to the composite structure model mentioned above. Its advantage lies in avoiding the catastrophic structural failure and sharp stress drop that occurs after the unit cell reaches its yield strength. Furthermore, the composite structure model exhibits superior overall mechanical properties (elastic modulus increased by 300%, yield strength increased by 100%). From a material-saving perspective, compared to a standard rhombic dodecahedron (control group) with similar mechanical properties, 8.3% hard-phase reinforcement saves approximately 13% of material while maintaining a similar stress-strain curve to the control group, while 50% hard-phase reinforcement saves approximately 25%. This innovative design is expected to play a significant role in the future field of bone implants, reducing manufacturing costs, improving surgical outcomes, and enhancing the patient experience. Attached Figure Description

[0022] Figure 1 A schematic diagram of the three-dimensional model and stress analysis of the soft phase unit cell.

[0023] Figure 2 A schematic diagram of a three-dimensional model and stress analysis of a hard phase unit cell;

[0024] Figure 3 A schematic diagram showing a 50% doping model of both soft and hard phases, along with a locally enlarged portion.

[0025] Figure 4 A cross-sectional model of 50% doping of soft and hard phases and a schematic diagram of the arrangement of soft and hard phases;

[0026] Figure 5Preliminary experimental original structure, optimized structure, and statistical charts of experimental data; Detailed Implementation

[0027] To make the objectives and technical solutions of this invention clearer and easier to understand, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0028] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0029] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of the present invention.

[0030] like Figure 1As shown in (a), this invention designs a microstructure for bone implants enhanced by polycrystalline doping to improve mechanical properties. The reference design considers overall performance, and the overall design should not be abandoned simply to improve stress concentration. Since the more important mechanical design index of the interbody fusion device is that its elastic modulus is similar to that of human bone, and it mainly bears the vertical gravitational load, the need for a negative Poisson's ratio structure is not obvious. Therefore, after comprehensively considering the geometric shapes of body-centered cubic, face-centered cubic, dodecahedron, diamond, etc., which have been well studied, this study adopts the rhombic dodecahedron structure, which is easy to manufacture and has sufficient overall performance. Its basic shape is used as the soft phase. The soft phase cell structure refers to the cell structure obtained by constructing cylindrical supports with a diameter of d according to the edge positions of the rhombic dodecahedron, and then incorporating the constructed support structure into a cube with a side length of c. The soft phase cell structure mainly utilizes the diameter d of the cylindrical support to drive the change in cell porosity. The side length of the cell is c. The specific structural parameters of this patent are as follows: the modeling of the rhombic dodecahedral soft phase cell is completed with d = 0.3 mm and c = 2 mm.

[0031] like Figure 1 As shown in (b), this is a stress cloud diagram of a soft phase unit cell under load. The darker areas in the diagram are the stress concentration areas. It can be seen that stress concentration occurs at the junctions of the various pillars of the unit cell and at the eight pillars of the unit cell that connect with the vertices of the circumscribed cube, which will produce large displacement deformation.

[0032] like Figure 2 As shown in (a), this is a three-dimensional model of a hard phase unit cell. After studying damage resistance optimization strategies for different structural unit doping, a hard phase unit cell structure, namely a rhombic dodecahedral structure with reinforcing ribs, was designed to facilitate mutual doping of the hard and soft phases and to allow for later improvement of the doping ratio. Specifically, based on the soft phase unit cell structure (i.e., the normal rhombic dodecahedral unit cell structure), four reinforcing ribs are added around the perimeter, vertically connected to corresponding pillars. These four reinforcing ribs are positioned along a set of opposite edges of the cube circumscribed by the rhombic dodecahedral unit cell, i.e., four edges extending in the same direction, to enhance its cellular mechanical properties. This structure does not rely on scaling down the original dodecahedron to improve performance; the reinforcing ribs can produce a significantly better performance improvement effect. Furthermore, since its unit cell size is consistent with the outer contour geometry of the soft phase unit cell, it allows for very convenient interfacial bonding between different phases.

[0033] like Figure 2As shown in (b), the stress cloud diagram of the hard phase cell under load is shown. The darker areas in the diagram are the stress concentration areas. Compared with the stress cloud diagram of the soft phase cell under load, it can be seen that the stress concentration at the junctions of the various pillars of the cell and the eight pillars of the cell that connect with the vertices of the external cube are greatly improved. In particular, the displacement deformation at the eight pillars with added stiffeners is also significantly reduced, indicating that the stiffeners significantly improve the mechanical properties of the original soft phase cell.

[0034] like Figure 3 (a) shows an overall schematic diagram of the soft and hard phase doped structure designed in this invention. It is divided into two parts: a core and a shell. The soft and hard phase cells are uniformly doped as the core to improve the damage resistance performance. The outer shell is wrapped with a hard phase to form a support shell. Its advantage is that it solves the problem of the inflexible spatial distribution of soft and hard phases and is easy to manufacture because there are reinforcing ribs under its diagonal bar, which is conducive to rapid prototyping. The advantage of this model is that it prevents the generation and propagation of high shear bands and achieves the design requirements for damage resistance.

[0035] like Figure 3 (b) shows a partially enlarged schematic diagram of the soft and hard phase doped structure designed in this invention. The right side of the image shows the soft phase core, and the lower left side shows the hard phase shell and the doping interface between the two phases.

[0036] like Figure 4 (a) is a schematic diagram of the cross-sectional position of the soft and hard phase doped structure designed in this invention. In order to better show the internal structure and the specific doping method of the soft and hard phases, a cross-sectional method is used. The figure shows in detail that the position of the cross-sectional plane is at the doping interface between the hard phase shell and the soft phase core on the right side.

[0037] like Figure 4 (b) shows a cross-sectional view of the soft and hard phase doped structure designed in this invention. The main viewing direction is the direction perpendicular to the cross-section. The left figure is a partial enlarged view of the cross-sectional main view, in which it can be observed that the left side of the partial view is the hard phase shell and the right side is the core. The right figure is a partial enlarged view of the cross-sectional top view, in which it can be observed that the left side of the partial view is the hard phase shell and the right side is the core. The middle figure is a schematic diagram of the position of the two partial enlarged views in the overall structure.

[0038] The soft and hard phase doping scheme designed in this invention has undergone compression pre-experiment performance testing with a light-curable resin as the material. Through compression pre-experiment, the compressive performance of different structures with and without doping was compared, proving that soft and hard phase doping can effectively improve mechanical properties. After multiple independent repeated experiments, compression performance data of different doping schemes were obtained.

[0039] like Figure 5(a) shows a physical image of the photocurable resin with a 50% soft and hard phase doping structure designed in this invention. The physical dimensions of the photocurable resin are all 48*36*36mm. The control group is a fully soft phase, and the experimental group is a 50% soft and hard phase interlayer doping structure.

[0040] like Figure 5 (b) shows the experimental process of the 50% soft and hard phase doped structure photocurable resin designed in this invention under a compressor.

[0041] like Figure 5 (c) shows the stress-strain curves obtained from the compression test of the 50% soft-hard phase doped photocurable resin of the present invention and the control group (all-soft phase structure). The compression test stress-strain curve is divided into three parts: linear elastic state (1) until the pillar yields due to bending or stretching, plateau state (2) during which the cells begin to gradually collapse, as buckling, brittle fracture or yielding depends on the substrate and morphology, and finally densification stage (3), corresponding to the collapse of cells one by one (the pillars reach contact). Among them, the first segment of the curve is due to the elastic response of the structure, that is, the elastic deformation of the pillar in the linear elastic state. In this stage, the strain of the pillar increases linearly with the increase of loading, while the stress of the pillar is proportional to the strain. This is because the pillar exhibits elastic behavior in this stage, that is, the pillar can recover to its original state after loading. The second segment of the curve is due to the gradual collapse of the unit cells. In this stage, the strain of the pillar continues to increase, but the stress stops increasing and remains relatively stable. This is because the pillar begins to collapse and generate tiny cracks, thereby increasing the surface area for energy absorption. This stage is also called the plateau stage because the stress is almost constant, indicating that the pillar absorbs a large amount of energy in this stage. The third curve represents densification due to the collapse of cells. At this stage, the reduced distance between the supports leads to contact. At this point, the supports in the model have reached their limit and can no longer absorb any more energy.

[0042] The soft-hard phase doped structure designed in this invention, using a 50% hard phase reinforcement model, exhibits a slow stress decrease followed by gradual stabilization after reaching yield strength. This phenomenon can be explained by the following model: the reinforcing pillars, in a linear elastic state, act as supports for the main structure, thereby significantly increasing the elastic modulus of the porous structure. However, in a single-pillar model, the structure undergoes catastrophic failure after reaching yield strength, with a sharp drop in stress. However, using a composite structure, with support provided by rhombic dodecahedrons, slows the stress decrease and inherits the energy absorption characteristics of the rhombic dodecahedral lattice structure.

[0043] The stress-strain curve of the soft-hard phase doped structure designed in this invention, with 8.3% hard phase reinforcement at high porosity (80% porosity), closely resembles that of a standard rhombic dodecahedron, except for the increased elastic modulus. The stress-strain curve of 50% hard phase reinforcement conforms to the composite structure model described above. Its advantage lies in avoiding the catastrophic structural failure and sharp stress drop that occurs after the unit cell reaches its yield strength. Furthermore, the composite structure model exhibits better overall mechanical properties (300% increase in elastic modulus and 100% increase in yield strength). From a material-saving perspective, compared to a standard rhombic dodecahedron (control group) with the same mechanical properties, 8.3% hard phase reinforcement saves approximately 13% of material while maintaining a similar stress-strain curve to the control group, while 50% hard phase reinforcement saves approximately 25%.

[0044] The soft-hard phase doped structure designed in this invention has a relatively small impact on the elastic modulus (with appropriate improvement) and porosity of the model when the hard phase doping of about 50% is small.

[0045] The bone implant structure designed in this invention, based on the enhancement of mechanical properties through polycrystalline structure, possesses excellent comprehensive mechanical properties and damage resistance.

[0046] The specific examples described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may modify or supplement the described specific examples or adopt similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

[0047] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Any simple modifications, alterations, or equivalent structural changes made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A microstructure for bone implants based on enhanced mechanical properties through polycrystalline doping, characterized in that, Microstructures of bone implants with enhanced mechanical properties through polycrystalline doping include soft-phase cell structures, hard-phase cell structures, and soft-hard phase doped structures. A blocky structure constructed by completely overlapping the corresponding cross-sections of the circumscribed cube of each soft-phase cell, with face-to-face bonding, and through mirroring or arraying operations, is called a soft-phase core. The shell-like structure constructed by mirroring or arraying operations, where the corresponding cross-sections of the circumscribed cube of each hard phase cell completely overlap and are face-to-face bonded, is called the hard phase shell. The soft phase core is bonded to the hard phase shell on the outside of the soft phase core structure. The cross-sections of the corresponding circumscribed cubes of each cell of the hard phase shell structure and the cell of the soft phase core structure completely overlap and are face-to-face bonded, constructing a soft-hard phase doped structure in which the hard phase shell completely encloses the soft phase core. The bonding surface between the soft phase core and the hard phase shell is the cross-section of the circumscribed cube of each cell. The soft phase cell structure adopts a regular rhombic dodecahedral cell structure, and the rhombic dodecahedron is inscribed in a cube. The three-dimensional structure of this cell mainly uses the diameter d of the pillars to drive the change of cell porosity. The layout of the pillar diameters is the edges of the rhombic dodecahedron. The cell pillars are formed by rotating the drawn cross-sectional sketch along the central axis. The hard phase cell structure design is a rhombic dodecahedron structure with four reinforcing ribs added to the soft phase structure. These four reinforcing ribs are set along a set of opposite edges of the cube inscribed by the rhombic dodecahedron cell, that is, the four edges with the same extension direction. The so-called soft and hard phase doped structure is divided into two parts: a soft phase core and a hard phase shell. The soft phase cell forms the core to improve the mechanical properties of damage resistance. A layer of hard phase cell structure is wrapped around the soft phase core to form a supporting shell, that is, the hard phase shell. The soft and hard phase doped structure is divided into two parts: a soft phase core and a hard phase shell. Since the soft phase cell structure has no reinforcing ribs, its elastic modulus and compressive strength are lower than those of the hard phase cell structure. The soft phase cell structure array stack is used as the core to improve the damage resistance and accommodate plastic deformation. A hard phase shell composed of all-hard phase cells is wrapped around the soft phase core. Due to the reinforcing rib design of the hard phase cell structure, the hard phase shell formed by stacking hard phase cells provides higher mechanical strength to improve the load-bearing capacity of the overall soft and hard phase doped structure.

2. The microstructure of a bone implant based on polycrystalline doping for enhanced mechanical properties according to claim 1, characterized in that, The soft phase cell structure refers to a structure based on a rhombic dodecahedron structure. It is constructed using solid cylindrical supports with a diameter of d, according to the positional relationship of the edges of the rhombic dodecahedron. The constructed support structure is then inscribed in a cube with a side length of c. The intersection of the rhombic dodecahedron is the center of each face of the cube. The soft phase cell structure uses the diameter d of the cylindrical support to drive the change in cell porosity. The side length of the cell is c. The specific structural parameters are as follows: the modeling of the rhombic dodecahedron soft phase cell is completed with d=0.3mm and c=2mm.

3. The microstructure of a bone implant based on polycrystalline doping for enhanced mechanical properties according to claim 1, characterized in that, The soft phase core of the soft-hard phase doped structure is formed by the complete overlap of the corresponding cross-section of the outer cube of each soft phase cell, so that each soft phase cell structure is tightly attached to the cross-section of the outer cube, completing the connection between the soft phase cells. Then, according to the soft-hard phase doping ratio, the final overall structure is constructed by mirroring or arraying.

4. The microstructure of a bone implant based on polycrystalline doping for enhanced mechanical properties according to claim 1, characterized in that, The outer shell of the soft and hard phase doped structure is formed by the complete overlap of the corresponding cross-section of the outer cube of each hard phase cell. Each hard phase cell structure is tightly fitted to the cross-section of the outer cube, completing the connection between the hard phase cells. Then, based on the size of the soft phase core and the soft and hard phase doping ratio, the final overall structure is constructed by mirroring or arraying.

5. The microstructure of a bone implant based on polycrystalline doping for enhanced mechanical properties according to claim 4, characterized in that, The shell of the soft and hard phase doped structure has a larger bonding area between hard phase cells than between soft phase cells. In addition to being tightly fitted at the cross-section of the corresponding circumscribed cube, each cell structure also forms a bonding surface with the cross-section formed by the corresponding reinforcing ribs of the hard phase cell and the circumscribed cube.

6. The microstructure of a bone implant based on polycrystalline doping for enhanced mechanical properties according to claim 1, characterized in that, The combination of the soft phase core and hard phase shell of the soft and hard phase doped structure first requires stacking the soft phase core according to the soft and hard phase doping ratio and the final structure size. Then, on the outside of the soft phase core, the corresponding outer cubic cross-sections of the hard phase cell and the soft phase cell are completely overlapped to construct the hard phase shell, which completely encloses the soft phase core. The bonding surface between the soft phase core and the hard phase shell is the cross-section of the outer cubic of each corresponding cell.

7. The microstructure of a bone implant based on polycrystalline doping for enhanced mechanical properties according to claim 1, characterized in that, The soft and hard phase doping structure has a soft and hard phase doping ratio of 50%. This structure requires the construction of a basic soft and hard phase doping structure with a total of 7*7 unit cells in the planar dimension. The soft phase unit cells are inside, with an arrangement of 5*5. The hard phase shell is to cover the periphery of the soft phase core, so the hard phase unit cells are arranged in 6*4. Based on this doping structure, various larger-sized soft and hard phase doping structures with a soft and hard phase doping ratio of 50% can be constructed.

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