具有抗菌性的低成本Ti-15Mo（-Ag）合金的激光原位合金化及其生物相容性研究

钛合金由于具有优异的综合性能（如较高的强度、延展性、较好的抗腐蚀性能和生物相容性等），在许多应用领域都受到了研究者的重视。在诸多3D打印技术中，选区激光熔化（selective laser melting，SLM）技术具有操作简单、近净成形、容易制备复杂结构等优点。本文利用SLM技术可以方便调控合金成分的优势，通过激光原位合金化，将球磨改性的氢化脱氢（hydride-dehydrate, HDH）钛粉与SLM技术相互结合，成功制备了成形质量较好的Ti-15Mo合金材料。同时对成形样品的微观结构以及强度、塑性、弹性模量等物理力学性能进行了系统研究。对SLM工艺参数对于合金性能的影响进行了系统研究，最终发现在P=274 W，v=600 mm/s的工艺参数下可以获得致密度较好的样品。使用Micro-CT技术对孔隙率进行分析，发现孔隙率仅有0.241%。使用COMSOL Multiphysics软件对该参数下的SLM制造过程中的温度场情况进行了有限元模拟，证明了对于高熔点元素Mo而言SLM技术也能够很好的将其熔化。此外，论文研究发现在引入少量Y元素之后，合金内部过高的O元素对于合金性能的负面影响得到了有效的控制。文章还对热处理工艺对于Ti-15Mo合金的影响进行了研究。结果发现，低温热处理可以有效的促进合金强度的提高，这归功于热处理会使得合金内的α-Ti相析出有关，但是其同时导致了合金的塑性降低。与此同时，较高温度的热处理可以有效的促进基体中Mo元素向β-Ti基体内部扩散，并且可以保证内部组织的均一性。最后，本文对加入Ag后的Ti-15Mo-0.2Y-xAg合金的反射率以及生物相容性进行了研究。加入高反射率元素Ag之后的粉体反射率无明显变化，制备的Ti-15Mo-0.2Y-xAg合金具有良好的抗菌性。

Titanium alloys have received great attention of researchers in many research fields, because of their excellent outstanding properties (such as high strength and ductility, well corrosion resistance and biocompatibility). Selective Laser Melting technology has the advantages of simple operation, near-net forming, and easy preparation of complex structures. In this thesis, SLM technology was used because it can easily control the composition of alloy. Through the in-situ laser alloying method, modified HDH-Ti powder prepared by ball milling and SLM technology are combined, to mitigate the high cost problem in raw materials. Ti-15Mo alloy, an established biomedical Ti alloy, with good printability was prepared. First of all, the influence of the SLM process parameters on the properties of the prepared parts was studied, and experiments with multiple sets of process parameters were tried, and finally determined that the best process parameters P=274 W, v=600 mm/s. Micro-CT was used to analyze the porosity, and it was found that the porosity of the sample is 0.241%. The COMSOL Multiphysics software was used to perform the finite element simulation of the change of temperature during the SLM forming process under this parameter, proving that SLM technology can also be used for printing the high melting point element such as Mo. In addition, the thesis found that after the introduction of the Y element, the influence of the excessive O element on the alloy properties has been effectively controlled, the α-Ti phase structure promoted by the O element has been significantly reduced, and the ductility of the Ti-15Mo alloy has been improved.The thesis also discussed the effect of heat treatment on Ti-15Mo alloy. It shows that the tensile strength has effectively been promoted by low-temperature heat treatment. It is because of the increase in the α-Ti phase in the alloy after heat treatment, but this also leads to a decrease in the ductility of the Ti-15Mo alloy. The diffusion of the Mo element can be effectively promoted after high-temperature heat treatment. Also it can ensure the uniformity of the microstructure.Finally, this thesis studied the reflectance and biocompatibility of Ti-15Mo-0.2Y-xAg alloy. After the addition of Ag, there is no significant change in the powder absorptivity. The Ti-15Mo-0.2Y-xAg alloy has been confirmed to have anti-bacterial property.