钛合金材料因其综合性能优异已成为国防先进装备及国民经济重大工程的重要和关键支撑材料，但其热加工过程中塑性低、变形抗力大等缺点极大的限制了钛合金的应用。申请人的前期探索表明适量合金元素铁（Fe）可明显改善钛合金的热加工性能，然而相关机制尚需进一步探索。本申请以Ti-6Al-4V合金为研究对象，重点从Fe微合金化角度通过研究Fe元素的占位及分布，探讨其对钛合金相组成、相分数及相稳定性的影响，明确Fe诱导的相转变与流变应力间的关联关系；研究高温变形过程中合金的微观组织演变，分析晶粒细化及两相形态对流变应力的影响；考察Fe元素对位错滑移势垒和临界剪切力的影响，揭示位错运动对流变应力的影响机制；研究高温变形中Fe元素与晶界的作用及其扩散规律，揭示Fe微合金化与界面协同作用对流变应力的影响机制。研究成果将为突破基于制备加工工艺优化的钛合金低成本关键技术奠定理论基础。

Titanium and its alloys are becoming one of the most important supporting materials for national advanced defense equipments and major national engineering projects due to their excellent comprehensive performance. However, there are several facts that still restrict their wider application such as low plasticity and high deformation resistance during hot working. Our previous study shows that the addition of Fe element can significantly improve the hot workability of titanium alloys while the relevant mechanism is still missing. In this application, we take Fe-microalloyed Ti-6Al-4V titanium alloys as the research object. We investigate the occupation and distribution of Fe element in Ti-6Al-4V alloys and the effect of Fe element on the formation of phase composition, phase fraction and phase stability to clarify the relationship between Fe-induced phase transition and flow stress. The microstructure evolution of the alloy during high temperature deformation is studied to analyze the effect of grain refinement and two-phase morphology on flow stress. We investigate the influence of Fe element on the dislocation slip barrier and critical shear force to reveal the mechanism of the effect of dislocation motion on the flow stress. We study the effect of Fe element and grain boundary and its diffusion law during high temperature deformation to reveal the influence of Fe element and interfacial interaction on the flow stress. The results will provide a necessary theoretical support to improve the hot working technology and reduce the hot working cost of high performance titanium alloys.