航空发动机阻燃钛合金力学性能预测及成分优化

钛合金广泛应用于航空航天、生物医学等领域。但由于其力学性能不理想（如硬度低、耐磨性差）和加工性差，限制了其应用范围。为了直接近净成形出结构复杂且性能提升的钛合金零部件。本文在选区激光熔化（SLM）Ti6Al4V钛合金过程中通入氮气（N₂），通过Ti-N反应制备钛基复合材料（TMCs）。该创新方法的成形原理为：激光诱导Ti6Al4V高温熔池附近的N₂分解生成N原子或者离子，并与熔融状态的钛原位反应生成TiN增强相，通过层层叠加，成形TiN增强钛基复合材料。本文采用3种不同体积分数（3%、10%和30%）的N₂气氛SLM成形了钛基复合材料，并对比了纯氩气（Ar）气氛中SLM成形的Ti6Al4V钛合金。采用扫描电子显微镜（SEM）观察了材料的微观组织。X射线衍射（XRD）图谱表明部分N固溶进入Ti晶格中。能谱（EDS）证实了TiN的生成。高分辨透射电镜（HR-TEM）图进一步确认了基体相和第二相分别为Ti和TiN。这种原位合成的氮化物增强相分散均匀，尤其是在低体积分数N₂气氛（3%和10%）下制备的复合材料中均匀分布着大量纳米级增强相。此外，在低体积分数N₂气氛（10%）下制备的复合材料强度和塑性同时提高。本文研究了不同N₂浓度对钛基复合材料微观组织和力学性能的影响规律，并阐明了复合材料的强韧化机理。

Practical strategy to construct anti-osteosarcoma bone substitutes by loading cisplatin into 3D-printed titanium alloy implants using a thermosensitive hydrogel

Titanium alloys are extensively used in areas such as aerospace and biomedicine. However, inadequate mechanical qualities (e.g., low hardness and poor wear resistance) and poor machinability limit the scope of their application expansion. To directly manufacture near-net-shape titanium alloy components with complicated architectures and improved performances, titanium matrix composites (TMCs) were fabricated based on the Ti–N reaction by introducing nitrogen gas (N₂) in the process of selective laser melting (SLM) of Ti6Al4V. The formation principle of this novel method is as follows: Laser-induced N₂ decomposition near the melt pool of Ti6Al4V generates N atoms or ions, which react with Ti atoms in the melt pool to in-situ synthesize TiN-reinforcement particles. In turn, TiN-reinforced Ti6Al4V matrix composites are manufactured layer-by-layer. This approach has some important advantages, which are as follows: Above all, in-situ gas-liquid synthesized reinforcements are equally dispersed due to N₂, good diffusivity and dispersibility. Furthermore, extremely small gas molecules have the potential to produce nanoscaled reinforcement. Moreover, the in-situ reaction mode produces a clean interface and strong interfacial bonding between the matrix and reinforcement. In this study, TMCs were prepared by SLM in three different N₂ volume fractions of 3%, 10% and 30%, which were compared to the Ti6Al4V alloy fabricated in an argon atmosphere. The microstructures were observed by SEM. Interstitial solid solutions of N in the Ti lattices were confirmed by XRD patterns. The presence of TiN was verified by EDS. The high-resolution transmission electron microscope (HR-TEM) picture indicated that the matrix and reinforcement were TiN and Ti, respectively. Such in situ synthesized nitride reinforcements were uniformly distributed; in particular, numerous nanoscale reinforcements were uniformly dispersed in the composites manufactured in low volume fraction N₂ atmospheres (3% and 10%). Additionally, the improved strength and plasticity were simultaneously achieved in a diluted N₂ atmosphere (10%). The effect of varying N₂ concentrations on the microstructure and mechanical characteristics of the TMCs was investigated. The content of the TiN particles increased with increasing N₂ concentration due to the increased availability of N atoms and ions for nucleation and growth of the reinforcement. Nevertheless, the TMC produced in a high N₂ atmosphere (30%) demonstrated degradation of the mechanical properties (particularly plasticity and ultimate strength) because of the presence of excessive N solid solutions and brittle TiN particles. The strengthening mechanisms were primarily grain refinement strengthening of the Ti matrix due to the