梯度多孔钛合金材料是指其孔结构在某个取向上呈梯度变化的多孔材料。它不仅具有完全与人体骨骼匹配的弹性模量，还可以通过孔隙的梯度分布调节，达到提高多孔材料整体强度、减轻应力集中避免功能突变的目的，在医疗领域具有很大发展潜力。本项目拟利用电子束熔化逐层成形法（AM-EBM）制备梯度孔隙分布Ti-6Al-4V开孔多孔材料，结合实验研究和有限元模拟，研究应力控制下不同梯度孔隙分布对多孔Ti-6Al-4V材料循环蠕变行为（循环加速或减速）的影响，考察梯度多孔Ti-6Al-4V材料孔壁在循环应力作用下的位错组态、滑移特征等组织变化、硬化软化规律，阐明孔壁材料的循环形变特性与梯度多孔材料循环蠕变之间的关系，揭示梯度孔隙分布Ti-6Al-4V多孔材料循环形变及疲劳失效机制。该项目的完成不仅可为预测和评价梯度孔隙多孔材料的疲劳性能奠定理论基础，还可为梯度多孔Ti-6Al-4V材料的优化设计和实际应用提供指导。

Graded porous titanium alloys refer to porous materials with graded porosity along a certain direction. They possess Young's modulus completely compatible with human bones and by adjusting the graded porosity, their strength can be improved and the stress concentration can be reduced simultaneously, which have great potetial application in medical implant field. In this proposal, the open cellure Ti-6Al-4V meshes will be fabricated by Additive manufacturing via Electron Beam Melting (AM-EBM). Through the combinination of experimental investigations and finite element calculations, the effect of different graded porosity on the cyclic ratcheting behaviour of Ti-6Al-4V meshes will be studied. The dislocation structures, slip characteristics, hardening or softening in the cell walls of Ti-6Al-4V meshes with graded porosity during the cyclic deformation will be investigated to elucidate their relationship with the cyclic ratcheting behaviour. With these studies, we try to understand the fatigue mechanism of Ti-6Al-4V meshes with graded porosity. The fulfillment of the project will not only establish a theoretical base for evaluating and forcasting the fatigue life of porous Ti-6Al-4V with graded porosity, but also guide their optimum design and actual medical applications.