剧烈塑性变形对钛合金热氧化的影响

钛合金热氧化通过在表面形成氧化层和氧扩散层改善其综合性能。热氧化前对钛合金进行剧烈塑性变形可以引入高密度晶界、位错、孪晶界等晶体缺陷及高畸变能，能够促进氧原子吸附、降低氧化物形核温度、加速氧化膜生长并促进氧原子向基体内的扩散，形成更厚、更致密的氧化层和更深的氧扩散区，获得更好的性能。本文对剧烈塑性变形钛合金的热氧化进行综述。首先，介绍了几种常见的剧烈塑性变形方法，总结了钛合金剧烈塑性变形和热氧化复合处理的工艺情况和处理效果。然后，根据氧化物形成的一般过程阐述了剧烈塑性变形引起的微观结构变化对氧原子吸附、氧化物形核、氧化膜形成、氧化膜增厚和氧扩散区形成的影响机理。最后，总结了剧烈塑性变形对氧化膜厚度、氧扩散区范围和氧化物形貌等热氧化微观结构及硬度、摩擦磨损等力学性能的影响，指出了当前研究中存在的问题，并展望了未来的研究方向。

Influence of severe plastic deformation on thermal oxidation of titanium alloys

Thermal oxidation of titanium alloys can improve their overall properties by forming an oxide layer and an oxygen diffusion layer on the surface. Severe plastic deformation of titanium alloys before thermal oxidation can introduce crystal defects such as high density of grain boundaries, dislocations, twin boundaries and high distortion energy, which can promote the absorption of oxygen atom, reduce oxide nucleation temperature, accelerate the growth of oxide film, and promote the diffusion of oxygen atoms into the matrix. Thus, a denser and thicker oxide layer and a deeper oxygen diffusion zone can be formed to obtain better performance. In the study, thermal oxidation of severe plastic deformed titanium alloys is review. Firstly, several common methods of severe plastic deformation are introduced, and the processing conditions and treatment effects of the combined treatment of severe plastic deformation and thermal oxidation of titanium alloys are summarized. Then, according to the general process of oxide formation, the influence mechanism of microstructure changes caused by severe plastic deformation on the absorption of oxygen atom, the nucleation of oxide, the formation of oxide film, the thickening of oxide film and the formation of oxygen diffusion zone is explained. Finally, the effects of severe plastic deformation on thermal oxidation microstructure such as the thickness of oxide film, the range of oxygen diffusion zone and the oxide morphology, as well as the mechanical properties such as hardness, friction and wear, are summarized. The existing problems in the current research are presented, and the future research directions are prospected.