Characterization and orientation-dependent strengthening behavior of intragranular TiC nanoplatelets in titanium matrix composites

We present here the intrinsic strengthening mechanism of newly developed Ti8C5 nanoplatelet reinforcement in titanium matrix composites (TMCs) and the significant impact of their orientation characteristics on the mechanical properties and deformation behavior of Ti matrix. The unique two-dimensional structure, uniform intragranular distribution, and locally aligned orientation of nanoplatelets provide exceptional strengthening efficiency and a distinctive strengthening mechanism. The nanoplatelets significantly strengthened the Ti matrix by impeding dislocation motion on prismatic and basal slip planes, resulting in massive dislocation pile-up. Moreover, the activation of pyramidal slip system induced geometrically necessary dislocations to accommodate plastic deformation, thereby maintaining considerable ductility. Micro-compression studies revealed a strong dependence on strengthening behavior and effectiveness on the spatial orientation and the direction of local alignment of nanoplatelets. The maximum strengthening effect is achieved when the platelet planes align parallel to the loading direction, with compressive ultimate and yield strengths of 2.9 and 1.9 GPa, respectively. In contrast, increasing the angle between platelet plane and loading direction led to the evolution of platelet/α-Ti interface into a pseudo-slip system, which severely deteriorated both strength and ductility. These fundamental insights provide an optimal spatial architecture for fabricating high-performance alignment-strengthened TMCs together with a feasible tailoring strategy. [Display omitted]