Structure and mechanical properties of in-situ titanium matrix composites with homogeneous Ti5Si3 equiaxial particle-reinforcements

Ti-based composites with homogeneous Ti5Si3 particle-reinforcements (Ti5Si3p) was successfully fabricated by spark plasma sintering at 1100 °C and 1200 °C. Microstructure, microhardness and compressive properties of such as-sintered composites were investigated. The Ti5Si3p were in-situ synthesized in Ti matrix by the reaction sintering of Ti/Si mixture powders, and subsequently grown into the equiaxial shape. The higher sintering temperature promoted the grain growth of Ti5Si3p, resulting into the coarsening of Ti5Si3p. As the same composition, comparing with the as-cast specimen with quasi-continuous Ti5Si3 network distribution, the as-prepared Ti5Si3p/Ti composites exhibited the significantly higher hardness and room-temperature compressive strength. For the composite fabricated at 1100 °C, it exhibited the higher compressive strength, and the ultimate and yield strengths respectively reached to 2.34 GPa and 1.92 GPa. The homogeneous Ti5Si3 equiaxial particle-reinforcements are believed to be beneficial to load transfer in the composite. The relevant strengthening mechanisms involved in Ti5Si3p/Ti composite are discussed.