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.