Advanced tensile properties and strain rate sensitivity of titanium matrix composites reinforced with CaTiO₃ particles

In the present work, a novel reinforcement, i.e., CaTiO3 particles, was adopted to produce high performance Ti matrix composites (TMCs), via a powder metallurgy process followed by hot extrusion. The results revealed that the CaTiO3 particles successfully improved the strength of Ti without sacrificing the elongation to failure. In contrast with most of ceramic particles that decompose or react with Ti matrix, CaTiO3 particles remain chemically unchanged in the matrix. Importantly, unlike titanium carbide (TiC) and other chemically stable particles that are reported with sharp corner and irregular shapes, the CaTiO3 particles display a round profile that may weaken the stress concentration in the matrix. It is found that the yield strength increases from 406 MPa for pure Ti to more than 800 MPa for TMCs with only 2.5 wt% addition of CaTiO3, while maintaining the elongation to failure over 25%. The attractive mechanical property is attributed to the hardened grain boundaries and increased geometrically necessary dislocations (GNDs) caused by the CaTiO3 particles. Besides, the experimental results show that, due to the particle-induced strong dislocation pinning and GNDs hardening effect, the strain rate sensitivity was also found increased for TMCs.