Modulus-controllable bionic gradient porous medical titanium alloy and additive manufacturing process method thereof

Abstract

The invention discloses a modulus-controllable bionic gradient porous medical titanium alloy and an additive manufacturing process method thereof, and relates to the technical field of medical materials.The titanium alloy is formed by stacking a plurality of rhombic dodecahedron structures in the vertical direction; the rhombic dodecahedron structure is formed by stacking a plurality of rhombic dodecahedron structure layers with the same area, and each rhombic dodecahedron structure layer is formed by arranging a plurality of rhombic dodecahedron unit cell structures in an array mode in the same horizontal plane. And the top distances of the rhombic dodecahedron unit cell structures in the rhombic dodecahedron structures from top to bottom are sequentially increased. The elastic modulus can be effectively reduced to 0.14-0.43 GPa, the elastic modulus of the whole structure can be accurately controlled, and the stress shielding effect of the bone graft is relieved.

Description

Technical Field

[0001] This invention relates to a biomimetic gradient porous medical titanium alloy with controllable modulus and its additive manufacturing process, belonging to the field of medical materials technology. Background Technology

[0002] Currently, widely used medical metallic materials mainly include stainless steel, cobalt-based alloys, and titanium alloys. Compared to other metals, titanium alloys possess lower elastic modulus, lightweight yet high strength, and better biocompatibility, and are gradually replacing other materials as the main raw material for artificial joints and bone grafts. Among them, Ti-6Al-4V alloy is currently the most widely used medical titanium alloy. It has been applied clinically since the 1960s, exhibiting good mechanical and biological properties and economic efficiency. It is mainly used to manufacture orthopedic medical devices such as acetabular cups, femoral stems, and bone screws.

[0003] In clinical applications, medical alloys, due to their elastic modulus being much higher than that of human bone (~30 GPa), often trigger a "stress shielding effect," leading to atrophy of bone cells around the implanted device and premature device failure requiring secondary surgery. Therefore, it is necessary to significantly reduce the modulus of medical alloys to make them compatible with human bone.

[0004] The elastic modulus of Ti-6Al-4V alloy is approximately 110 GPa. A porous structure design is typically used to reduce this modulus. However, this approach presents two problems: firstly, traditional processing techniques struggle to precisely control the size and porosity of the porous structure, making precise control of the alloy modulus difficult; secondly, according to the Gibson-Ashby model, increasing the porosity effectively reduces the modulus, but simultaneously, the alloy strength also decreases significantly. While higher porosity promotes bone ingrowth and accelerates the integration of the implant with the bone, it is difficult to simultaneously maintain the mechanical properties of the implant.

[0005] Existing research results show that additive manufacturing technology can precisely control the preparation accuracy and porosity of porous structures. Uniform porous structures can achieve precise control of the elastic modulus of alloys, but it is still difficult to guarantee that the mechanical properties meet the requirements. At the same time, the failure mode of uniform porous structures is usually the rapid collapse of the overall structure, which is difficult to predict and take measures. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a biomimetic gradient porous medical titanium alloy with controllable modulus and its additive manufacturing process, which can effectively reduce the elastic modulus to 0.14~0.43GPa, accurately control the elastic modulus of the overall structure, and alleviate the stress shielding effect of bone grafts.

[0007] To achieve the above objectives, the present invention is implemented using the following technical solution: On one hand, the present invention provides a biomimetic gradient porous medical titanium alloy with controllable modulus. The titanium alloy is composed of multiple rhombic dodecahedral structures stacked vertically. The rhombic dodecahedral structure is composed of multiple rhombic dodecahedral structure layers of equal area stacked together. The rhombic dodecahedral structure layer is composed of multiple rhombic dodecahedral unit cells arranged in an array in the same horizontal plane. The apex distance of the rhombic dodecahedral unit cells in the rhombic dodecahedral structure layer increases sequentially from top to bottom.

[0008] Furthermore, the rhombic dodecahedral structure includes a first rhombic dodecahedral structure, a second rhombic dodecahedral structure, and a third rhombic dodecahedral structure; The first rhombic dodecahedral structure, the second rhombic dodecahedral structure, and the third rhombic dodecahedral structure are respectively composed of a first rhombic dodecahedral structure layer, a second rhombic dodecahedral structure layer, and a third rhombic dodecahedral structure layer; The first rhombic dodecahedral structure layer, the second rhombic dodecahedral structure layer, and the third rhombic dodecahedral structure layer are respectively composed of the first rhombic dodecahedral unit cell structure, the second rhombic dodecahedral unit cell structure, and the third rhombic dodecahedral unit cell structure.

[0009] Furthermore, the array consists of five rhombic dodecahedral unit cells arranged along both the X and Y axes.

[0010] Furthermore, the apex distance of the first rhombic dodecahedral unit cell structure is 2.5 mm, the apex distance of the second rhombic dodecahedral unit cell structure is 3.5 mm, and the apex distance of the third rhombic dodecahedral unit cell structure is 5 mm.

[0011] Furthermore, the porosity of the rhombic dodecahedral unit cell structure is 85%.

[0012] On the other hand, the present invention also provides an additive manufacturing process for a modulus-controllable biomimetic gradient porous medical titanium alloy as described in any of the preceding claims, comprising: Design alloy structure model; Additive manufacturing of an alloy structure model using Ti-6Al-4V powder, followed by cooling and cleaning, yields a biomimetic gradient porous medical titanium alloy with controllable modulus.

[0013] Furthermore, the design alloy structure model includes: The first, second, and third rhombic dodecahedral unit cell structures were drawn using 3D modeling software. The shape and thickness of the pore edges of the first, second, and third rhombic dodecahedral unit cell structures were adjusted to achieve a porosity of 85% for the rhombic dodecahedral unit cell structure. The first rhombic dodecahedral unit cell structure, the second rhombic dodecahedral unit cell structure, and the third rhombic dodecahedral unit cell structure are arranged in an array in the same horizontal plane to obtain the first rhombic dodecahedral structure layer, the second rhombic dodecahedral structure layer, and the third rhombic dodecahedral structure layer, respectively. The first rhombic dodecahedral structure, the second rhombic dodecahedral structure, and the third rhombic dodecahedral structure are respectively stacked to form the first rhombic dodecahedral structure, the second rhombic dodecahedral structure, and the third rhombic dodecahedral structure; The first rhombic dodecahedral structure, the second rhombic dodecahedral structure, and the third rhombic dodecahedral structure are stacked from top to bottom to obtain a three-dimensional titanium alloy structure; Calculate the elastic modulus of the titanium alloy three-dimensional structure. If the elastic modulus of the titanium alloy three-dimensional structure is greater than the preset value, increase the height of the first rhombic dodecahedron structure; otherwise, increase the height of the second and third rhombic dodecahedron structures until the elastic modulus of the titanium alloy three-dimensional structure reaches the preset value, thus obtaining the alloy structure model.

[0014] Furthermore, the method for calculating the elastic modulus of the titanium alloy three-dimensional structure includes: Calculate the elastic modulus of the first, second, and third rhombic dodecahedral structures and their volume fraction in the three-dimensional structure of the titanium alloy, respectively. Based on the elastic moduli of the first, second, and third rhombic dodecahedral structures and their volume fraction in the three-dimensional titanium alloy structure, the elastic modulus of the three-dimensional titanium alloy structure is calculated, and its expression is as follows: ; in, The elastic modulus of a titanium alloy's three-dimensional structure is represented by its elastic modulus. This represents the volume fraction of the first rhombic dodecahedral structure within the three-dimensional structure of the titanium alloy. This represents the elastic modulus of the first rhombic dodecahedral structure. This represents the volume fraction of the second rhombic dodecahedral structure within the three-dimensional structure of the titanium alloy. This represents the elastic modulus of the second rhombic dodecahedral structure. This represents the volume fraction of the third rhombic dodecahedral structure within the three-dimensional structure of the titanium alloy. This represents the elastic modulus of the third rhombic dodecahedral structure.

[0015] Furthermore, the heights of the first, second, and third rhombic dodecahedral structures are increased by integer multiples of the number of layers of the first, second, and third rhombic dodecahedral structures, respectively.

[0016] Furthermore, the additive manufacturing employs electron beam selective melting, which is achieved using electron beam selective melting equipment, wherein the vacuum level is evacuated to 10... -4 ~10 -6 The process was carried out in an atmosphere filled with helium and the atmosphere was filled with mbar. And / or, the particle size range of the Ti-6Al-4V powder is 45~106μm.

[0017] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: The modulus-controllable biomimetic gradient porous medical titanium alloy provided by this invention can effectively reduce the elastic modulus to 0.14-0.43 GPa, accurately control the overall structural elastic modulus, alleviate the stress shielding effect of bone grafts, and solve the problem of the difficulty in balancing high porosity and good mechanical properties in porous materials. The method for preparing biomimetic gradient porous medical titanium alloy with controllable modulus provided by this invention is simple and fast, saves raw materials, and has high forming accuracy. It can be applied to personalized bone grafts in various service environments. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the rhombic dodecahedral unit cell structure of a modulus-controllable biomimetic gradient porous medical titanium alloy in one embodiment of the present invention. Figure 2 This is a schematic diagram of the rhombic dodecahedral structure of a biomimetic gradient porous medical titanium alloy with controllable modulus in one embodiment of the present invention. Figure 3 This is a schematic diagram of the structure of a biomimetic gradient porous medical titanium alloy with controllable modulus in one embodiment of the present invention; Figure 4 This is a schematic diagram of the cubic unit cell structure of the alloy structure model of Comparative Example 1 of the present invention. Figure 5 This is a schematic diagram of the alloy structure model of Comparative Example 1 of the present invention. Detailed Implementation

[0019] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0020] This invention provides a biomimetic gradient porous medical titanium alloy with controllable modulus, which is composed of multiple rhombic dodecahedral structures stacked and arranged vertically, such as... Figure 3As shown, in this embodiment, the rhombic dodecahedral structure includes three types, from top to bottom: the first rhombic dodecahedral structure, the second rhombic dodecahedral structure, and the third rhombic dodecahedral structure. Each type of rhombic dodecahedral structure has the same porosity, and the area and shape of its cross-section are also identical, resulting in the biomimetic gradient porous medical titanium alloy having an overall rectangular parallelepiped shape.

[0021] The rhombic dodecahedral structure is composed of multiple stacked rhombic dodecahedral structural layers of equal area. The first, second, and third rhombic dodecahedral structures are respectively composed of the first, second, and third rhombic dodecahedral structural layers, as shown below. Figure 2 As shown, the number of stacked layers of the rhombic dodecahedral structure is determined based on the elastic modulus of the biomimetic gradient porous medical titanium alloy.

[0022] The rhombic dodecahedral structure layer is composed of multiple rhombic dodecahedral unit cells arranged in an array on the same horizontal plane. In this embodiment, the array arrangement is five rhombic dodecahedral unit cells arranged along both the X and Y axes. The first, second, and third rhombic dodecahedral structure layers are respectively composed of the first, second, and third rhombic dodecahedral unit cells.

[0023] The vertices distance of the rhombic dodecahedral unit cells in the rhombic dodecahedral structure increases sequentially from top to bottom. In this embodiment, the structures of the first, second, and third rhombic dodecahedral unit cells are as follows: Figure 1 As shown, the apex distance of the first rhombic dodecahedral unit cell structure is 2.5 mm, the apex distance of the second rhombic dodecahedral unit cell structure is 3.5 mm, the apex distance of the third rhombic dodecahedral unit cell structure is 5 mm, and the porosity of the rhombic dodecahedral unit cell structure is 85%.

[0024] This invention also provides an additive manufacturing process for a biomimetic gradient porous medical titanium alloy with controllable modulus, comprising: Design an alloy structure model, specifically including: The first, second, and third rhombic dodecahedral unit cell structures were drawn using 3D modeling software.

[0025] The shape and thickness of the pore edges of the first, second, and third rhombic dodecahedral unit cell structures are adjusted to achieve a porosity of 85% for the rhombic dodecahedral unit cell structure. This adjustment can be directly generated in 3D software and will not be elaborated on here.

[0026] The first, second, and third rhombic dodecahedral unit cell structures are arranged in an array on the same horizontal plane to obtain the first, second, and third rhombic dodecahedral structure layers, respectively.

[0027] The first rhombic dodecahedral structure, the second rhombic dodecahedral structure, and the third rhombic dodecahedral structure are respectively stacked to form the first rhombic dodecahedral structure, the second rhombic dodecahedral structure, and the third rhombic dodecahedral structure.

[0028] The first, second, and third rhombic dodecahedral structures are stacked sequentially from top to bottom to obtain a three-dimensional titanium alloy structure.

[0029] The elastic modulus of a three-dimensional titanium alloy structure is calculated using the following method in this embodiment: Calculate the elastic modulus of the first, second, and third rhombic dodecahedral structures and their volume fraction in the three-dimensional titanium alloy structure.

[0030] Based on the elastic moduli of the first, second, and third rhombic dodecahedral structures and their volume fraction in the three-dimensional titanium alloy structure, the elastic modulus of the three-dimensional titanium alloy structure is calculated, and its expression is as follows: ; in, The elastic modulus of a titanium alloy's three-dimensional structure is represented by its elastic modulus. This represents the volume fraction of the first rhombic dodecahedral structure within the three-dimensional structure of the titanium alloy. This represents the elastic modulus of the first rhombic dodecahedral structure. This represents the volume fraction of the second rhombic dodecahedral structure within the three-dimensional structure of the titanium alloy. This represents the elastic modulus of the second rhombic dodecahedral structure. This represents the volume fraction of the third rhombic dodecahedral structure within the three-dimensional structure of the titanium alloy. This represents the elastic modulus of the third rhombic dodecahedral structure.

[0031] If the elastic modulus of the titanium alloy three-dimensional structure is greater than the preset value, the height of the first rhombic dodecahedral structure is increased; otherwise, the heights of the second and third rhombic dodecahedral structures are increased until the elastic modulus of the titanium alloy three-dimensional structure reaches the preset value, thus obtaining the alloy structure model. It should be noted that the height of the rhombic dodecahedral structure must increase in integer multiples of the corresponding rhombic dodecahedral structure layer to ensure the same porosity.

[0032] Export the alloy structure model as an STL file, and then use slicing software to slice and export the alloy structure model.

[0033] Import the slice file into the electron beam selective melting equipment. Load the powder hopper with Ti-6Al-4V (ELI) powder with a particle size of 45~106μm. Prepare for printing. Evacuate the electron gun chamber to 10... -4 -10 -6 At mbar, high-purity helium is introduced to start printing. Process parameters include substrate preheating temperature of 730℃, melting beam current of 6-9mA, velocity function set to 35, defocusing amount set to 25, powder layer thickness of 0.07mm, and the melting area is gradually stacked to form the final part. Printing ends, resulting in a porous structure.

[0034] After the porous structure cools to room temperature in the equipment, it is removed and unmelted powder is removed with compressed air to obtain a shaped porous titanium alloy.

[0035] The porous titanium alloy was immersed in alcohol and ultrasonically cleaned for 5-6 minutes to remove incompletely sintered powder, resulting in a biomimetic gradient porous medical titanium alloy with controllable modulus.

[0036] The following analysis uses specific embodiments to illustrate the biomimetic gradient porous medical titanium alloy. Example 1

[0037] This invention provides an additive manufacturing process for a biomimetic gradient porous medical titanium alloy, comprising the following steps: (1) Use 3D modeling software to draw rhombic dodecahedral unit cell structures with top distances of 2.5mm, 3.5mm and 5mm respectively. Adjust the thickness of the pore edges to 0.45mm, 0.58mm and 0.75mm respectively, so that the porosity of the three rhombic dodecahedral unit cell structures is 85%.

[0038] (2) The three rhombic dodecahedral unit cell structures drawn in step (1) are arranged in a cyclic array. The array method is to arrange 5 rhombic dodecahedral unit cell structures along the X-axis and Y-axis to obtain a rhombic dodecahedral structure layer. Along the Z-axis, the rhombic dodecahedral structure layers composed of rhombic dodecahedral unit cell structures with top distances of 2.5mm, 3.5mm and 5mm are arranged in 6, 4 and 3 layers respectively to obtain three rhombic dodecahedral structures.

[0039] (3) Stack the rhombic dodecahedron structure obtained in step (2) in the Z-axis direction from top to bottom with top distances of 2.5mm, 3.5mm and 5mm to obtain the alloy structure model.

[0040] (4) The elastic moduli of the rhombic dodecahedral structure composed of rhombic dodecahedral unit cells with apex distances of 2.5 mm, 3.5 mm, and 5 mm are 0.14 GPa, 0.22 GPa, and 0.43 GPa, respectively. The rhombic dodecahedral structure composed of rhombic dodecahedral unit cells with apex distances of 2.5 mm, 3.5 mm, and 5 mm accounts for 34.1%, 31.8%, and 34.1% of the volume of the alloy structure model, respectively. Substituting these values ​​into the above formula for calculating the elastic modulus, the elastic modulus of the alloy structure model is obtained as 0.21 GPa, which meets the preset value.

[0041] (5) Export the total structure model as an STL format file, and use slicing software to slice and export the model.

[0042] (6) Import the slice file from step (5) into the electron beam selective melting equipment, load Ti-6Al-4V(ELI) powder with a particle size of 45-106μm into the powder hopper, prepare for printing, and evacuate the electron gun chamber to 10. -4 -10 -6 At mbar, high-purity helium is introduced to begin printing. The molten regions are stacked layer by layer to form the final part, and printing ends, resulting in a porous structure.

[0043] (7) Cool the porous structure from step (6) to room temperature in the equipment, remove the porous structure and remove the unmelted powder with compressed air to obtain the formed porous titanium alloy.

[0044] (8) Immerse the porous titanium alloy from step (7) in alcohol and ultrasonically clean it for 5 minutes to remove the incompletely sintered powder and obtain a complete biomimetic gradient porous medical titanium alloy.

[0045] Tests showed that the elastic modulus of the biomimetic gradient porous medical titanium alloy was 0.2 GPa, which is basically consistent with the calculated results, and its yield strength was 6.51 MPa.

[0046] Comparative Example 1: The difference between this comparative example and Example 1 is that the rhombic dodecahedral unit cell structure in Example 1 is changed to a cubic structure, such as... Figure 4 As shown, to ensure a porosity of 85%, the pore edge thicknesses of cubic unit cell structures with top distances of 2.5 mm, 3.5 mm, and 5 mm are 1.06 mm, 1.3 mm, and 1.4 mm, respectively. Based on this, the following results are obtained: Figure 5 The gradient porous structure shown.

[0047] It was verified that the elastic moduli of the cubic structures composed of cubic unit cell structures with top distances of 2.5 mm, 3.5 mm and 5 mm were 4.54 GPa, 6.62 GPa and 7.48 GPa respectively, and the elastic modulus of the alloy structure model was 5.92 GPa. It can be seen that the reduction effect of the elastic modulus of the alloy structure model in Comparative Example 1 was significantly weaker than that in Example 1.

[0048] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A modulus-controllable biomimetic gradient porous biomedical titanium alloy, characterized in that, The titanium alloy is stacked and arranged in a vertical direction by a plurality of rhombohedron dodecahedron structures, the rhombohedron dodecahedron structures are composed of a plurality of rhombohedron dodecahedron structure layers with equal areas, the rhombohedron dodecahedron structure layers are composed of a plurality of rhombohedron dodecahedron unit structures arranged in an array in the same horizontal plane, and the top distances of the rhombohedron dodecahedron unit structures in the rhombohedron dodecahedron structures from top to bottom are sequentially increased.

2. The modulus-controllable, biomimetic, gradient, porous, biomedical titanium alloy of claim 1, wherein, The rhombohedron dodecahedron structure comprises a first rhombohedron dodecahedron structure, a second rhombohedron dodecahedron structure and a third rhombohedron dodecahedron structure. The first rhombohedron dodecahedron structure, the second rhombohedron dodecahedron structure and the third rhombohedron dodecahedron structure are respectively composed of a first rhombohedron dodecahedron structure layer, a second rhombohedron dodecahedron structure layer and a third rhombohedron dodecahedron structure layer. The first rhombohedron dodecahedron structure layer, the second rhombohedron dodecahedron structure layer and the third rhombohedron dodecahedron structure layer are respectively composed of a first rhombohedron dodecahedron unit structure, a second rhombohedron dodecahedron unit structure and a third rhombohedron dodecahedron unit structure.

3. The modulus-controllable, biomimetic, gradient, porous, biomedical titanium alloy of claim 2, wherein, The array is arranged with five rhombohedron dodecahedron unit structures along the X axis and the Y axis.

4. The modulus-controllable, biomimetic, gradient, porous, biomedical titanium alloy of claim 2, wherein, The top distance of the first rhombohedron dodecahedron unit structure is 2.5 mm, the top distance of the second rhombohedron dodecahedron unit structure is 3.5 mm, and the top distance of the third rhombohedron dodecahedron unit structure is 5 mm.

5. The modulus-controllable, biomimetic, gradient, porous, biomedical titanium alloy of claim 1, wherein, The porosity of the rhombohedron dodecahedron unit structure is 85%.

6. A process for additive manufacturing of a controllable modulus biomimetic gradient porous biomedical titanium alloy as claimed in any one of claims 1 to 5, wherein, It comprises: designing an alloy structure model; using Ti-6Al-4V powder to additively manufacture the alloy structure model, and obtaining a biomimetic gradient porous medical titanium alloy with controllable modulus after cooling and cleaning.

7. The process method of additive manufacturing of controllable modulus biomimetic gradient porous biomedical titanium alloy according to claim 6, characterized in that, The design of the alloy structure model comprises: using a three-dimensional modeling software to draw a first rhombohedron dodecahedron unit structure, a second rhombohedron dodecahedron unit structure and a third rhombohedron dodecahedron unit structure; adjusting the hole edge shape and thickness of the first rhombohedron dodecahedron unit structure, the second rhombohedron dodecahedron unit structure and the third rhombohedron dodecahedron unit structure so that the porosity of the rhombohedron dodecahedron unit structure is 85%; arranging the first rhombohedron dodecahedron unit structure, the second rhombohedron dodecahedron unit structure and the third rhombohedron dodecahedron unit structure in an array in the same horizontal plane to obtain a first rhombohedron dodecahedron structure layer, a second rhombohedron dodecahedron structure layer and a third rhombohedron dodecahedron structure layer respectively; stacking the first rhombohedron dodecahedron structure layer, the second rhombohedron dodecahedron structure layer and the third rhombohedron dodecahedron structure layer to obtain a first rhombohedron dodecahedron structure, a second rhombohedron dodecahedron structure and a third rhombohedron dodecahedron structure respectively; stacking the first rhombohedron dodecahedron structure, the second rhombohedron dodecahedron structure and the third rhombohedron dodecahedron structure from top to bottom to obtain a titanium alloy three-dimensional structure; calculating the elastic modulus of the titanium alloy three-dimensional structure, if the elastic modulus of the titanium alloy three-dimensional structure is greater than a preset value, increasing the height of the first rhombohedron dodecahedron structure, otherwise increasing the height of the second rhombohedron dodecahedron structure and the third rhombohedron dodecahedron structure, until the elastic modulus of the titanium alloy three-dimensional structure reaches the preset value, and obtaining an alloy structure model.

8. The process method of additive manufacturing of controllable modulus biomimetic gradient porous biomedical titanium alloy according to claim 7, characterized in that, The method for calculating the elastic modulus of the titanium alloy three-dimensional structure comprises the following steps: respectively calculating the elastic modulus of the first, second and third rhombic dodecahedron structures and the volume fraction of the titanium alloy three-dimensional structure; calculating the elastic modulus of the titanium alloy three-dimensional structure according to the elastic modulus of the first, second and third rhombic dodecahedron structures and the volume fraction of the titanium alloy three-dimensional structure, and the expression is: ； wherein, E represents the elastic modulus of the titanium alloy three-dimensional structure, V1 represents the volume fraction of the first rhombohedral dodecahedron structure in the titanium alloy three-dimensional structure, E1 represents the elastic modulus of the first rhombohedral dodecahedron structure, V2 represents the volume fraction of the second rhombohedral dodecahedron structure in the titanium alloy three-dimensional structure, E2 represents the elastic modulus of the second rhombohedral dodecahedron structure, V3 represents the volume fraction of the third rhombohedral dodecahedron structure in the titanium alloy three-dimensional structure, E3 represents the elastic modulus of the third rhombohedral dodecahedron structure.

9. The process method of additive manufacturing of controllable modulus biomimetic gradient porous biomedical titanium alloy according to claim 7, wherein, The height of the first, second and third rhombic dodecahedron structures respectively corresponds to the integer multiple increase of the layer number of the first, second and third rhombic dodecahedron structure layers.

10. The process method of additive manufacturing of controllable modulus biomimetic gradient porous biomedical titanium alloy according to claim 6, wherein, The additive manufacturing employs an electron beam selective melting process, which is realized by an electron beam selective melting device, which is carried out under the atmosphere that the vacuum degree is extracted to 10 -4 ~10 -6 mbar and the helium gas is filled. And / or, the particle size range of the Ti-6Al-4V powder is 45-106 μm.

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