Fabrication and mechanical properties of TiC coated short carbon fiber reinforced Ti5Si3–TiC composites

Abstract

Ti5Si3-based composites reinforced with TiC-coated Cf and TiC particulate (TiC@Cf/Ti5Si3–TiC) were fabricated by spark plasma sintering. The performance of the TiC@Cf/Ti5Si3–TiC composite was comprehensively evaluated by investigating its mechanical properties at room temperature, as well as the thermal shock resistance, oxidation resistance and flexural strength at high temperatures. By employing optimal process parameters obtained through response surface methodology, the TiC@Cf/Ti5Si3–TiC composite exhibited a maximum room-temperature fracture toughness of 9.32 ± 1.05 MPa m1/2, which represented a significant increase of 261.2% and 23.1% compared to monolithic Ti5Si3 and TiC@Cf/Ti5Si3 composite, respectively. The flexural strength of the TiC@Cf/Ti5Si3–TiC composite measured at room temperature, 1000 °C, and after quenching from 1200 °C was 531 ± 61 MPa, 299 ± 43 MPa, and 138.4 ± 15 MPa, achieving an improvement of 221.8%, 128.2%, and 295.4% compared to monolithic Ti5Si3. The incorporation of TiC particulates appeared to mitigate the fiber-matrix interfacial reaction more effectively than that observed in the TiC@Cf/Ti5Si3 composite previously investigated. Consequently, the reinforcing mechanism of fiber pulling-out and debonding, crack blocking, deflection, and bridging was fully operational at heightened sintering temperatures. These essential factors play a vital role in remarkably enhancing the mechanical properties of the TiC@Cf/Ti5Si3–TiC composite.