High Strength and Toughness of In-Situ Ti-TiCx/Ti Laminated Composites by Using Ti3AlC2 as a Precursor

The main predicament currently encountered in titanium matrix composites (TMCs) is the trade-off between strength and toughness. In this work, in-situ Ti-TiCx/Ti laminated composites were prepared by hot-press sintering of Ti-Ti3AlC2 filled preceramic papers and Ti foils. In order to explore the effect of Ti3AlC2 precursor on the microstructure and properties of the prepared composites, preceramic papers with different contents of Ti3AlC2 (5-20 vol pct) were rationally tailored. The results show that the TiCx phase was in-situ generated through the reaction between Ti3AlC2 and Ti during the sintering process, while the de-intercalated Al atoms diffused into the Ti matrix to form a Ti(Al) solid solution. When the Ti3AlC2 content is 15 vol pct, the laminated composites exhibit the optimal mechanical properties, with flexural strength of 1358 MPa and fracture toughness of 31.87 MPa<middle dot>m1/2. The excellent matching for strength and toughness could be ascribed to TiCx second-phase strengthening and solid solution strengthening of Al atoms, while crack deflection, branching, and passivation in the laminated structure increased the crack extension path to toughen the composites.