Multiple ceramic particles help to improve oxidation resistance of TiAl alloy

A novel microstructural regulation strategy was utilized to improve the oxidation resistance of TiAl alloy by the controllable multiple ceramic particles. TiAl composites were prepared using spark plasma sintering (SPS) by introducing SiC and graphene oxide (GO). TiAl composites showed nearly full lamellar microstructure, and the Ti₅Si₃ particles in-situ precipitated at the lamellar colony boundaries and Ti₂AlC in-situ precipitated at the α₂/γ interfaces. Grain refinement of TiAl composite was obvious, displaying a decrease of lamellar colony size from 259 to 81 μm after addition 0.3 wt% SiC and 0.5 wt% GO. The isothermal oxidation results showed that the mass gain of TiAl composite was decreased by 56% compared to TiAl alloy after oxidation at 950 ℃ for 100 h. This was mainly attributed to the in-situ precipitated Ti₂AlC and Ti₅Si₃ ceramic particles inhabiting the interior diffusion of O atoms and the outward diffusion of Ti and Al atoms, then the activity of O and Ti was decreased. Furthermore, the Ti₂AlC and Ti₅Si₃ ceramic particles contributed to release the internal stress between the oxide layer and matrix, strengthening the bondability between the oxide layer and matrix.