Effect of alloying elements on the behaviour of TiAl-based alloys

TiAl-based alloys containing Nb, Mo and Cr have been produced by induction melting both under an Ar atmosphere and in vacuum. Fracture toughness and isothermal oxidation tests at 900 °C have been performed on a number of alloys in order to evaluate the effect of alloying elements on both fracture toughness and hot corrosion. The results highlighted that there is an alloy composition range that could allow to obtain a good compromise between high temperature oxidation resistance and fracture toughness. In fact only for a selected Al/Ti ratio and a limited content of alloying elements it is possible to attain the alloy microstructural control and, for Mo free alloys, good protectiveness against oxidation.