LAUSR

Abstract The samples of in-situ α2(Ti3Al) + γ(TiAl) matrix composite reinforced with Ti2AlC particles were prepared by a centrifugal casting of Ti-46.4Al-5.1Nb-1C-0.2B (at.%) alloy. The microstructure of the as-cast samples consists of equiaxed nearly lamellar α2 + γ grains with ribbon like TiB particles formed in the interdendritic region and homogenously distributed plate-like Ti2AlC particles distributed preferentially within the dendrites. The solution annealing of the samples in the α (Ti-based solid solution) phase field and subsequent air cooling (AC), oil quenching (OQ) and water quenching (WQ) leads to the formation of massive γM(TiAl). The subsequent annealing in the γ phase field followed by a stabilisation annealing at 900 °C leads to the formation of homogeneous fine-grained γ type of microstructure in the OQ and WQ samples. The solution annealing of the OQ and WQ samples in the α phase field followed by slow cooling results in the formation of equiaxed grains with nearly lamellar α2 + γ microstructure. The Vickers hardness and indentation elastic modulus strongly depend on the applied heat treatments. The in-situ composite with the coarse-grained lamellar microstructure shows improved creep resistance compared to that of some TiAl-based alloys with fully lamellar, nearly lamellar, convoluted or pseudoduplex microstructure.