激光选区熔化成型多孔Ti6Al4V合金及其热处理研究

Study on Porous Ti6Al4V Alloy Formed by Selective Laser Meltingand Its Heat Treatmente

摘要:

Ti6Al4V合金是骨科中应用最为广泛的钛合金,激光选区熔化成型多孔Ti6Al4V合金能够降低其弹性模量,减少应力遮挡现象,促进骨组织的长入,但成型件的塑性通常较低。为此设计了单元尺寸在1~2 mm、孔径约在500~1200 μm、孔隙率约在60%~90%之间的菱形十二面体多孔结构并采用激光选区熔化技术成型了压缩试件,通过压缩仿真和实验对其力学性能进行研究,并研究了退火热处理对其力学性能、显微组织的影响。仿真结果表明,对模型的支杆直径进行误差补偿可获得更为准确的结果。实验结果表明当单元尺寸为1.5 mm时,试件的抗压强度在78.16~242.94 MPa之间,弹性模量在1.74~4.17 GPa之间,与人体皮质骨的力学性能相近。经820 ℃退火2 h后试件的抗压强度、弹性模量与成型态基本保持相当,而塑性有所提升,因此更适用于骨科植入体。

Abstract:

Ti6Al4V alloy is the most widely used titanium alloy in orthopaedics. Selective laser melting of porous Ti6Al4V alloy can reduce its elastic modulus, reduce the stress shielding phenomenon, and promote the growth of bone tissue, but the plasticity of the formed parts is usually low. Therefore, rhombohedral dodecahedron porous structures with unit size of 1~2 mm, aperture of 500~1200 μm and porosity of 60%~90% are designed, and the compression specimens are formed by selective laser melting technology. The mechanical properties are studied by compression simulation and experiments, and the effects of annealing heat treatment on their mechanical properties and microstructure are also studied. The simulation results show that more accurate results can be obtained by error compensation for the strut diameter of the model. The experimental results show that when the unit size is 1.5 mm, the compressive strength and elastic modulus of specimens are between 78.16~242.94 MPa and 1.74~4.17 GPa, which are similar to the mechanical properties of human cortical bone. After annealing at 820 ℃ for 2 hours, the compressive strength and elastic modulus of the specimens are basically the same as those of the formed specimens, while the plasticity is improved, so they are more suitable for orthopedic implants.