Microstructural evolution and mechanical properties in rapid sintered Ti5Si3/Ti matrix composites with varying Si additions

Titanium matrix composites with varying Si additions were rapidly fabricated via spark plasma sintering, in-situ Ti₅Si₃ particles were synthesized through a rapid sintering reaction between Ti and Si powders. The Ti₅Si₃ particles were uniformly distributed within the Ti matrix of each sintered composite. As the Si content in the initial mixture increased, the size and quantity of the Ti₅Si₃ particles grew significantly. In composites with lower Si content, in-situ Ti₅Si₃ particles predominantly formed elongated rods, along with some coarse polygonal particles. With a further increase in Si content, Ti₅Si₃ particles primarily took on polygonal shapes. When the Si content reached 5.0 wt%, Ti₅Si₃ particles tended to transition into near-equiaxed structures. The semicoherent interface is formed between Ti and Ti₅Si₃ phases, which greatly preserves the plastic deformation ability, even with a significant increase in yield strength as the silicon content increases to 5 %. The evolution of in-situ Ti₅Si₃ and its corresponding mechanical effect were discussed.