Achieving high strength-ductility in TiBw-GNPs/Ti6Al4V composites via 3D interface configuration

Strong interface bonding is critical to achieve the graphene nanoplates reinforced titanium matrix composites (GNPs/TMCs) with excellent strength and ductility. In this study, the TiBw-GNPs/Ti6Al4V composites with three-dimensional (3D) interface configuration are fabricated through the combination of vibration milling and the spark plasma sintering (SPS). The 3D interface configuration is constructed by the in-situ generated TiB whiskers (TiBw) together with the sandwiched TiC-GNPs-TiC, in which TiBw grow epitaxially into the adjacent Ti6Al4V grains and immobilize TiC-GNPs-TiC. As a result, 1.5 wt%TiBw-GNPs/Ti6Al4V composite exhibit simultaneously improved yield strength, ultimate strength and ductility, manifesting marked increments of 26.5%, 26.4% and 30.1% compared to GNPs/Ti6Al4V composite, respectively. The strengthening enhancement of TiBw-GNPs/Ti6Al4V composites can be mainly attributed to the constructed 3D interface microstructure, which boosts the interface bonding and promotes grain refinement as well as load transfer. Moreover, the equiaxed α-Ti phase and the deformation compatibility gifted from the tailored interface endow the TiBw-GNPs/Ti6Al4V composites with excellent ductility. This strategy of tailoring 3D interface configuration could pave a promising way to obtain robust interfacial bonding and break through the strength-ductility trade-off in graphene reinforced titanium matrix composites.