Gradient materials have significant potential to break strong plastic tradeoffs. Graphene with a strong affinity for titanium alloys has an influential application value for material modification. In this study, microstructure evolution and deformation behavior of graphene-based TiC/Ti6Al4V composites processed by friction stir processing (FSP) have been investigated. Electron backscattered diffraction (EBSD) reveals uniform microstructure in the stir zone (SZ). Transmission electron microscopy (TEM) observations reveal distinct microstructures at different depths from the processed surface. The SZ includes nano/micro grains and TiC nanoplates. Twin structure exists in both α matrix and TiC. Stress-induced martensitic transformation is suppressed. As depth increases, TiC gradually disappears and the FSP-induced texture {-2116} < 2–1–11 > becomes slightly stronger. Moreover, there exists special crystallographic orientation relation: (1 1 1)TiC//(0001)Ti. In the base metal (BM), larger grains are observed, and dislocation structure becomes the dominant defect feature. Nanoindentation results show that hardness decreases first and then increases from the processed surface to the bulk metal. The distribution of hardness is the result of combined action of strengthening effect of TiC twins and deformation adaptation effect of α twins.

梯度材料具有打破塑料权衡的巨大潜力。石墨烯对钛合金具有很强的亲和力，在材料改性方面具有重要的应用价值。在这项研究中，研究了通过搅拌摩擦加工 (FSP) 加工的石墨烯基 TiC/Ti6Al4V 复合材料的微观结构演变和变形行为。电子背散射衍射 (EBSD) 揭示了搅拌区 (SZ) 中的均匀微观结构。透射电子显微镜 (TEM) 观察揭示了距加工表面不同深度的不同微观结构。SZ 包括纳米/微米晶粒和 TiC 纳米板。α基体和TiC均存在孪晶结构。应力诱发的马氏体相变被抑制。随着深度的增加，TiC 逐渐消失，FSP 引起的织构 {-2116} < 2-1-11 > 变得稍微强一些。此外，还存在特殊的晶体取向关系：（1 1  1)TiC//(0001)Ti。在基底金属 (BM) 中，观察到较大的晶粒，位错结构成为主要的缺陷特征。纳米压痕结果表明，从加工表面到大块金属，硬度先降低后升高。硬度分布是TiC孪晶的强化作用和α孪晶的变形适应作用共同作用的结果。