Synthesis, microstructure and mechanical properties of Ti_3SiC_2-TiC composites pulse discharge sintered from Ti/Si/TiC powder mixture

摘要

Ti_3SiC_2-TiC composites with the volume fractions of TiC from 0 to 90% were fabricated by pulse discharge sintering (PDS) technique using Ti-Si-TiC as starting powders in the sintering temperature range of 1250-1400℃. Phase content and microstructure of the synthesized samples were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The samples sintered at 1400 ℃ are almost fully dense for all compositions with relative density higher than 98%. The phase distribution in the synthesized samples is non-uniform. The Vickers hardness increases almost linearly with the volume fraction of TiC up to a value of 20.1 ± 1.4 GPa at 90 vol.% TiC. The flexural strength increases with the volume fraction of TiC to a maximum value of 655±10MPa at 50 vol.% TiC. The relationship between microstructure and mechanical properties is discussed.