A TC4 alloy material and its preparation method and application

Abstract

The present invention belongs to the technical field of medical materials, and specifically relates to a TC4 alloy material and its preparation method and application. The TC4 alloy material provided by the present invention comprises a stacked plywood layer and a unit cell lattice layer; the upper surface and the lower surface of the TC4 alloy material are respectively plywood layers, and the number of layers of the unit cell lattice layer is 2 or 4; the thickness of the plywood layer is 1 mm, and the unit cell unit in the unit cell lattice layer is a rhombic dodecahedron, and the edge length of the rhombic dodecahedron is n, and n is any value of 3 to 4 mm; when the number of layers of the unit cell lattice layer is 2, the single layer thickness of the unit cell lattice layer is 2n-1; when the number of layers of the unit cell lattice layer is 4, the single layer thickness of the unit cell lattice layer is n-1. The present application adds a plywood layer to the TC4 alloy material to improve the stress concentration at the nodes of the lattice structure, resulting in the uniform dispersion of the stress distribution on the nodes, which greatly improves the fatigue resistance of the porous structure material.

Description

Technical Field

[0001] The present invention belongs to the technical field of medical materials, and in particular relates to a TC4 alloy material and a preparation method and application thereof. Background Art

[0002] With the development of bone transplantation and artificial prosthesis transplantation technology, the demand for bone and knee / hip implant materials in the medical field has continued to grow, which has greatly stimulated the development of biomaterials. TC4 alloy has great application prospects in the field of bone implant medicine due to its high strength, excellent ductility, excellent corrosion resistance and good biocompatibility. At the same time, its porous structure makes it lightweight, which can effectively reduce the elastic modulus, solve the problem of "stress shielding", and can meet the requirements of high-quality implants. It has broad application prospects in the medical field.

[0003] However, bone implant materials must not only withstand static loads in the human body, but also long-term dynamic cyclic loads. Therefore, it is of great significance to focus on the research of the fatigue performance of porous structures to improve the mechanical and fatigue properties of porous implants. At present, implant materials are mainly prepared by additive manufacturing (AM) technology, but when the unit cell of the porous structure is certain, the fatigue resistance of the porous structure prepared by AM is poor, which seriously affects the service life of the material. Summary of the invention

[0004] In view of this, the present invention provides a TC4 alloy material and a preparation method and application thereof. The TC4 alloy material provided by the present invention has good fatigue resistance and can extend its service life as a bone transplant or prosthetic transplant material.

[0005] In order to solve the above technical problems, the present invention provides a TC4 alloy material, comprising a stacked sandwich layer and a unit cell lattice layer;

[0006] The upper surface and the lower surface of the TC4 alloy material are respectively sandwich layers, and the number of layers of the unit cell lattice layer is 2 or 4; the thickness of the sandwich layer is 1 mm, and the unit cell unit in the unit cell lattice layer is a rhombic dodecahedron, and the edge length of the rhombic dodecahedron is n, and n is any value from 3 to 4 mm; when the number of layers of the unit cell lattice layer is 2, the single layer thickness of the unit cell lattice layer is 2n-1; when the number of layers of the unit cell lattice layer is 4, the single layer thickness of the unit cell lattice layer is n-1.

[0007] Preferably, the height×width×length of the TC4 alloy material is (4n+1)×2n×2n, and the height×width×length of the plywood layer is 1×2n×2n; n is the edge length of the rhombic dodecahedron.

[0008] The present invention also provides a method for preparing the TC4 alloy material described in the above technical solution, comprising the following steps:

[0009] After modeling, the model is sliced;

[0010] The TC4 alloy material is obtained by performing 3D printing using TC4 alloy powder as a raw material.

[0011] Preferably, the average particle size of the TC4 alloy powder is 15 to 53 μm.

[0012] Preferably, the TC4 alloy powder is prepared by a gas atomization method.

[0013] Preferably, the conditions for the 3D printing are: laser power of 170 to 210 W, scanning speed of 1000 to 1600 mm / s, scanning spacing of 0.08 to 0.12 mm, powder layer thickness of 0.03 to 0.06 mm, and scanning strategy of alternating 60 to 90° scanning vectors.

[0014] Preferably, the software used for modeling and model slicing processing is Magics software.

[0015] The present invention also provides the use of the TC4 alloy material described in the above technical solution or the TC4 alloy material prepared according to the preparation method described in the above technical solution as a bone transplant or prosthetic transplant material.

[0016] The present invention provides a TC4 alloy material, comprising stacked sandwich layers and unit cell lattice layers; the upper surface and the lower surface of the TC4 alloy material are sandwich layers respectively, and the number of layers of the unit cell lattice layer is 2 or 4; the thickness of the sandwich layer is 1 mm, and the unit cell unit in the unit cell lattice layer is a rhombus dodecahedron, and the edge length of the rhombus dodecahedron is n, and n is any value of 3 to 4 mm; when the number of layers of the unit cell lattice layer is 2, the single layer thickness of the unit cell lattice layer is 2n-1; when the number of layers of the unit cell lattice layer is 4, the single layer thickness of the unit cell lattice layer is n-1. The maximum stress of TC4 alloy material without sandwich layer (only unit cell lattice layer) is concentrated at the intersection nodes of the pore-struts of the rhombic dodecahedron. These nodes are stress concentration areas. With the addition of sandwich layer, the stress concentration at the nodes of the lattice structure is significantly improved, and the bending buckling performance of the component is improved (the bending strain of the central node is limited by the sandwich layer), resulting in the uniform dispersion of stress distribution at the nodes. The stress is decomposed to the positions of each pore-strut and node, which greatly improves the fatigue resistance of the pore structure material. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The result of stress analysis of a unit cell (rhombic dodecahedron);

[0018] Figure 2The structural schematic diagrams and physical pictures of the TC4 alloy materials prepared in Examples 1 and 2 and Comparative Example 1 are shown, wherein (a) is a structural schematic diagram and (b) is a physical picture;

[0019] Figure 3 This is a three-dimensional physical picture of the TC4 alloy material prepared in Example 1;

[0020] Figure 4 The TC4 alloy materials prepared in Examples 1 and 2 and Comparative Example 1 are cumulative strain curves with cycle changes, wherein (a) is a cumulative strain curve of L0 with cycle changes, (b) is a cumulative strain curve of L1 with cycle changes, and (c) is a cumulative strain curve of L3 with cycle changes;

[0021] Figure 5 The finite element analysis results of the TC4 alloy materials prepared in Examples 1 and 2 and Comparative Example 1 are obtained, wherein (a) is the finite element analysis result of L0, (b) is the finite element analysis result of L1, and (c) is the finite element analysis result of L3;

[0022] Figure 6 The engineering compressive stress-strain curves of the TC4 alloy materials prepared in Examples 1 and 2 and Comparative Example 1 are shown;

[0023] Figure 7 SN dot-line diagram of the TC4 lattice structure of L0, L1, and L3 in the sandwich layer of the TC4 alloy material prepared in Examples 1, 2 and Comparative Example 1. DETAILED DESCRIPTION

[0024] The present invention provides a TC4 alloy material, comprising a stacked sandwich layer and a unit cell lattice layer; the upper surface and the lower surface of the TC4 alloy material are sandwich layers respectively. In the present invention, the number of layers of the unit cell lattice layer is 2 or 4. In the present invention, the number of layers of the sandwich layer is 1 more than the number of layers of the unit cell lattice layer. In the present invention, the unit cell unit in the unit cell lattice layer is a rhombus dodecahedron, the edge length of the rhombus dodecahedron is n, and n is any value of 3 to 4 mm, preferably 3 mm; the pore-edge angle of the rhombus dodecahedron is preferably 36°. In the present invention, the porosity of the unit cell is preferably 51 to 71%. In the present invention, when the number of layers of the unit cell lattice layer is 2, the single layer thickness of the unit cell lattice layer is 2n-1; when the number of layers of the unit cell lattice layer is 4, the single layer thickness of the unit cell lattice layer is n-1; the thickness of the sandwich layer is 1 mm. In the present invention, the nodes of the rhombic dodecahedron as a unit cell are connected to each other to form a three-dimensional array. The present invention limits the thickness of the unit cell lattice layer and the sandwich layer to the above range to ensure that the sandwich layer directly contacts the nodes of the rhombic dodecahedron, which is beneficial to improve the fatigue resistance of the material.

[0025] The stress types on the porous structure can be decomposed into bending stress and buckling stress, which are affected by the geometric shape of the unit cell. Under the action of compressive load, the cumulative effect of bending and buckling of the support plate has a great influence on the mechanical properties of the porous structure. The present invention improves the bending and buckling properties of the component by introducing a sandwich structure formed by a plywood layer, thereby improving the strength and ductility of the component. Figure 1 is the result of stress analysis on the unit cell (rhombic dodecahedron) model; O and M are any two adjacent nodes in the lattice structure, P is the positive pressure, P1 is the bending stress component, and P2 is the buckling stress component. Bending deformation is easier than buckling deformation, and it is obvious that P1>P2. Therefore, for the structure without plywood layers, the main bending deformation is P1, resulting in premature fatigue failure; after the introduction of the plywood layer, the sandwich structure restricts the movement of the bending deformation, resulting in the stress being evenly dispersed from the central node to the surrounding area during the fatigue process, reducing the stress concentration at the central node and greatly improving the fatigue performance.

[0026] In the present invention, the height×width×length of the TC4 alloy material is preferably (4n+1)×2n×2n, and the height×width×length of the plywood layer is preferably 1×2n×2n; n is the edge length of the rhombic dodecahedron. In an embodiment of the present invention, the height×width×length of the TC4 alloy material is 13mm×6mm×6mm, and the height×width×length of the plywood layer is 1mm×6mm×6mm.

[0027] The present invention also provides a method for preparing the TC4 alloy material described in the above technical solution, comprising the following steps:

[0028] After modeling, the model is sliced;

[0029] The TC4 alloy material is obtained by performing 3D printing using TC4 alloy powder as a raw material.

[0030] The present invention performs model slicing after modeling. The present invention preferably performs modeling, model slicing and 3D printing according to the laser selective melting technology (SLM). In the present invention, the software used for modeling and model slicing is preferably Magics software.

[0031] After the model is sliced, the present invention uses TC4 alloy powder as a raw material for 3D printing to obtain the TC4 alloy material. In the present invention, the TC4 alloy powder is preferably prepared by a gas atomization method. In the present invention, the average particle size of the TC4 alloy powder is preferably 15 to 53 μm, and more preferably 15 to 39.7 μm.

[0032] In the present invention, the conditions of the 3D printing are preferably: laser power of 170-210W, scanning speed of 1000-1600mm / s, scanning spacing of 0.08-0.12mm, powder layer thickness of 0.03-0.06mm, and scanning strategy of alternating 60-90° scanning vectors; more preferably: laser power of 190W, scanning speed of 1400mm / s, scanning spacing of 0.1mm, powder layer thickness of 0.03mm, and scanning strategy of alternating 67° scanning vectors. The present invention adopts the above-mentioned 3D printing condition parameters to reduce the residual stress caused by local heating and rapid cooling, and strengthen the combination of adjacent tracks and layers.

[0033] The design of sandwich structure in porous TC4 alloy material changes the stress distribution of support and nodes, thus changing the fatigue deformation mechanism of the structure. The present invention designs and prepares TC4 alloy (ɑ+β type) sandwich structures with different sandwich layer configurations through additive manufacturing technology. The results show that the significant improvement of the fatigue resistance of the sandwich structure is due to the structure reducing the stress concentration at the nodes and changing the deformation mode of the porous structure.

[0034] The present invention also provides the use of the TC4 alloy material described in the above technical solution or the TC4 alloy material prepared by the preparation method described in the above technical solution as a bone transplant or prosthetic transplant material.

[0035] In order to further illustrate the present invention, the technical solutions provided by the present invention are described in detail below in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0036] Example 1

[0037] The TC4 alloy material model was obtained by using Magics software for modeling. In the model, the sandwich layer and the unit cell lattice layer were stacked, wherein the unit cell lattice layer had 4 layers, the thickness of each unit cell lattice layer was 2 mm, the edge length of the rhombic dodecahedron in the unit cell lattice layer was 3 mm, the pore-edge angle was 36°, and the porosity of the unit cell of the rhombic dodecahedron was 71%. The sandwich layer was 1 mm thick and had 5 layers. The TC4 alloy material was a cuboid, and the height×width×length of the cuboid was 13 mm×6 mm×6 mm.

[0038] The TC4 alloy material model was sliced ​​using Magics software and then 3D printed with TC4 alloy powder with an average particle size of 39.7 μm prepared by a gas atomization method as raw material to obtain TC4 alloy material, recorded as L3; the 3D printing conditions were: laser power of 190 W, scanning speed of 1400 mm / s, scanning spacing of 0.1 mm, powder layer thickness of 0.03 mm, and scanning strategy of alternating 67° scanning vector alternating scanning.

[0039] Example 2

[0040] The TC4 alloy material is prepared according to the method of Example 1, except that the number of unit cell lattice layers is 2, the thickness of each unit cell lattice layer is 5 mm, the edge length of the rhombic dodecahedron in the unit cell lattice layer is 3 mm; the number of plywood layers is 3; and the obtained TC4 alloy material is recorded as L1.

[0041] Comparative Example 1

[0042] The TC4 alloy material is prepared according to the method of Example 1, except that the number of unit cell lattice layers is 1, the thickness is 11 mm, the edge length of the rhombic dodecahedron in the unit cell lattice layer is 3 mm; the number of plywood layers is 2; and the obtained TC4 alloy material is recorded as L0.

[0043] Figure 2 The schematic diagrams and actual pictures of the TC4 alloy materials in Examples 1 and 2 and Comparative Example 1 are shown in FIG. 1 , wherein (a) is a schematic diagram of the structure and (b) is an actual picture. Figure 3 This is a three-dimensional physical picture of the TC4 alloy material prepared in Example 1.

[0044] Six groups of high cycle fatigue tests were performed on the TC4 alloy materials prepared in Examples 1, 2 and Comparative Example 1, respectively. The stress ratio was R=0.1, the test frequency was 10 Hz, the waveform was a sine wave, and the applied load was 2500N-3750N (each increase of 250N was a test load). The specific test condition parameters are shown in Table 1. After six groups of tests, the strain accumulation curves of the sandwich lattice structure samples with the number of cycles were summarized as follows: Figure 4 As shown, (a) is the cumulative strain curve of L0 changing with the number of cycles, (b) is the cumulative strain curve of L1 changing with the number of cycles, and (c) is the cumulative strain curve of L3 changing with the number of cycles.

[0045] Table 1 Test condition parameters of high cycle fatigue test

[0046]

[0047]

[0048] The reflection and prediction of fatigue life is usually analyzed by strain-life curves tested under cyclic loading, such as Figure 4As shown in the figure, it can be seen from the logarithmic coordinates that the trend of strain ε accumulation with the number of cycles N can be roughly divided into three stages: Stage I is N < 100, which is characterized by a relatively obvious strain accumulation in the initial stage; Stage II is 100 < N < Nc (the strain inflection point is shown as Nc in Figure (a)), and this stage is characterized by a relatively constant strain accumulation rate or a very small accumulation within a relatively long range of cycles; Stage III is the stage of rapid strain increase after exceeding the inflection point Nc. The strain inflection point Nc will continue to decrease with the increase of the applied stress. At the same time, it is found that the more interlayers there are in the lattice structure, the strain inflection point Nc will obviously shift to the right, and the mechanical properties stability and fatigue performance of the structure will be significantly enhanced. Figure 4 It can be concluded that the fatigue life of the lattice structures of different interlayers (L0, L1, L3) depends largely on the second stage of fatigue strain accumulation. The strain rate in the second stage of the L3 fatigue strain process is the lowest and the fatigue life is the longest.

[0049] Finite element analysis was performed on the TC4 alloy materials prepared in Examples 1, 2 and Comparative Example 1, and the results were as follows: Figure 5 As shown, (a) is the finite element analysis result of L0, (b) is the finite element analysis result of L1, and (c) is the finite element analysis result of L3. Figure 5 It can be seen that the maximum stress concentration of the no-reinforcement layer (L0) occurs at the nodes where the pores and struts intersect. These nodes are stress concentration areas. With the addition of the reinforcement layer (L3), the stress concentration at the nodes of the lattice structure is significantly optimized, and the bending performance of the component is improved, resulting in the uniform distribution of stress at the nodes, which is evenly decomposed into each pore-strut and node position.

[0050] The TC4 alloy materials prepared in Examples 1, 2 and Comparative Example 1 were subjected to mechanical static compression tests to obtain engineering compressive stress-strain curves as shown in the figure below: Figure 6 The obtained performance parameters of compressive strength, yield strength and ductility are listed in Table 2.

[0051] Table 2 Mechanical properties of TC4 alloy materials prepared in Examples 1, 2 and Comparative Example 1

[0052] Test Materials Compressive strength(Mpa) Yield Strength(Mpa) Ductility(%) L0 108 83 7.5 L1 120 94 6.7 L3 148 125 5.5

[0053] Depend on Figure 6It can be seen that all compression curves (solid lines) have three deformation stages, namely the initial linear elastic deformation stage, the platform plastic deformation stage and the densification process stage (porous gradual compaction). The compressive strength of the L0 sample is the lowest, and it breaks when the strain reaches 7.5%. The compressive strength of the L1 sample (120MPa) is significantly improved (by about 12Mpa), but the ductility is slightly reduced. The compressive strength of the L3 sample is further improved, and an obvious platform effect appears in the strain process. The L3 sample has multiple strain inflection points at the same time, showing an obvious densification process. The compressive yield strength of L3 (125MPa) is nearly 50% higher than that of L0 (83MPa).

[0054] according to Figure 4 The stress-life curves (fatigue SN curves) of the TC4 alloy materials prepared in Examples 1, 2 and Comparative Example 1 are obtained by calculating the number of cycles at fatigue failure of the strain-life curve. Figure 7 As shown. Figure 7 It can be seen that the fatigue performance of L3 far exceeds that of L0 and L1. 6 At the same time, the fatigue strength of L1 (25Mpa) is about 1.25 times that of L0 (20Mpa), and the fatigue strength of L3 (50MPa) is about 2.5 times that of L0 (20Mpa).

[0055] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A TC4 alloy material, characterized in that: It includes stacked sandwich layers and unit cell lattice layers; The upper surface and the lower surface of the TC4 alloy material are sandwich layers respectively, and the number of layers of the unit cell lattice layer is 2 or 4; the thickness of the sandwich layer is 1 mm, and the unit cell unit in the unit cell lattice layer is a rhombic dodecahedron, and the edge length of the rhombic dodecahedron is n, and n is any value of 3 to 4 mm; when the number of layers of the unit cell lattice layer is 2, the single layer thickness of the unit cell lattice layer is 2n-1; when the number of layers of the unit cell lattice layer is 4, the single layer thickness of the unit cell lattice layer is n-1; The height×width×length of the TC4 alloy material is (4n+1)×2n×2n, and the height×width×length of the sandwich layer is 1×2n×2n.

2. The method for preparing the TC4 alloy material according to claim 1, comprising the following steps: After modeling, the model is sliced; The TC4 alloy material is obtained by performing 3D printing using TC4 alloy powder as a raw material.

3. The preparation method according to claim 2, characterized in that: The average particle size of the TC4 alloy powder is 15-53 μm.

4. The preparation method according to claim 2 or 3, characterized in that: The TC4 alloy powder is prepared by gas atomization method.

5. The preparation method according to claim 2, characterized in that: The 3D printing conditions are as follows: laser power of 170-210 W, scanning speed of 1000-1600 mm / s, scanning spacing of 0.08-0.12 mm, powder layer thickness of 0.03-0.06 mm, and scanning strategy of alternating 60-90° scanning vectors.

6. The preparation method according to claim 2, characterized in that: The software used for modeling and model slicing processing is Magics software.

7. Use of the TC4 alloy material according to claim 1 or the TC4 alloy material prepared by the preparation method according to any one of claims 2 to 6 as a bone transplant or prosthetic transplant material.

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