Micron-sized SiC particles reinforced TC4 composites: Mechanical properties and strengthening mechanisms

SiC fiber, W fiber, C fiber and other continuous fiber-reinforced titanium matrix composites (TMCs) have limited their application prospects due to their anisotropy, interface reaction, and high costs. In contrast, the SiC particles (SiCp) reinforced TMCs are of particular interests due to their ease of fabrication, lower costs, and isotropic properties. Micron-sized SiCp reinforced TC4 (Ti-6Al-4V) composites (SiCp/TC4) were synthesized via spark plasma sintering (SPS). The microstructure and mechanical properties of SiCp/TC4 composites have been investigated. The results showed that SiCp/TC4 composites exhibite a typical Widmanstatten structure composed of plate α, grain boundary α phase, and intercrystalline β phase. TiC particles formed via the reaction of SiCp with the TC4 matrix distributed at grain boundaries. In the meanwhile, a small amount of Ti5Si3 have been observed around the β phase. The strength of the composites increased continuously with the increase of SiCp contents. Due to effects of grain refinement and load transfer strengthening and solution strengthening from C, O and Si elements, the composites of 0.5 wt% SiCp/TC4 has achieved a high yield strength and an ultimate tensile strength of 1053 MPa and 1144 Mpa, which are higher than TC4 matrix for 33.5% and 27.1%. SiCp/TC4 composites have widespread application prospects in aerospace, military and automotive industries.