Interfacial reactions and mechanical properties of SiC fiber reinforced Ti3SiC2 and Ti3(SiAl)C2 composites

In this paper, SiC fiber (SiCf) reinforced Ti3SiC2 and Ti3(SiAl)C2 composites were fabricated by spark plasma sintering at 1250 degrees C and 1300 degrees C for 10 min, respectively. The interfacial reactions between fibers and matrix, as well as the mechanical properties of the two composites, were investigated. XRD, SEM and TEM were used to characterize the phase compositions and microstructures of the as-synthesized composites. The results showed that no interfacial reaction occurred between SiCf and Ti3SiC2 matrix, while it occurred between SiCf fiber and Ti3(SiAl)C2 matrix. In the latter case, the interfacial reaction layer was mainly composed of SiC, TiC, and TiSi2 phases, and its thickness was about 1.2 mu m. Besides, due to the introduction of SiC fibers, both bending strength and fracture toughness of two composites were improved. Based on the investigation of crack propagation, it was proposed that the main strengthening and toughening mechanism was crack bowing for SiCf/Ti3(SiAl)C2 composite, while was fiber pullout, fiber debonding, and residual thermal stress for SiCf/Ti3SiC2 composite.