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

Abstract Ti-based composites with homogeneous Ti 5 Si 3 particle-reinforcements (Ti 5 Si 3 p) 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 Ti 5 Si 3 p 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 Ti 5 Si 3 p, resulting into the coarsening of Ti 5 Si 3 p. As the same composition, comparing with the as-cast specimen with quasi-continuous Ti 5 Si 3 network distribution, the as-prepared Ti 5 Si 3 p/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 Ti 5 Si 3 equiaxial particle-reinforcements are believed to be beneficial to load transfer in the composite. The relevant strengthening mechanisms involved in Ti 5 Si 3 p/Ti composite are discussed.