Microstructural and mechanical characterization of in-situ TiC/Ti titanium matrix composites fabricated by graphene/Ti sintering reaction

In-situ TiC/Ti titanium matrix composites were successfully fabricated through a novel approach, utilizing the reaction of graphene and Ti mixture powders in spark plasma sintering. Microstructure, hardness and compressive properties of such composites were investigated. The layered graphene nanosheets as the carbon source were dispersed in the powders, and subsequently formed uniform TiC particles in Ti matrix during the rapid sintering. The resulting TiC particles exhibited the micro- and nano-sized equiaxial structures. Such composites possessed the significantly enhanced hardness and room-temperature compressive strength comparing with the as-cast and as-sintered pure Ti. The ultimate and yield compressive strengths of as-prepared 7.0 vol% TiC incorporated composite respectively reached up to 2.64 GPa and 1.93 GPa, beyond some advanced Ti materials reported to date. In-situ micro- and nano-sized TiC particles were believed to be beneficial to harden and strengthen Ti matrix. The relevant strengthening mechanisms of such composites were discussed.