Published online by Cambridge University Press: 15 February 2011
A range of TiAl-based alloys have been produced by plasma melting either small buttons (1kg samples) or ingots (up to 50kg). Some of the ingots have been atomised. The influence of thermomechanical processing on the microstructure of these materials has been assessed using optical and electron microscopy and the room temperature mechanical properties and creep strengths determined. It has been found that either through appropriate processing and/or through alloy development, it is possible to obtain alloys with room temperature strengths up to 1000MPa. Elongations of about 1% at room temperature have been obtained for alloys with this strength and this is coupled with significant improvements in creep strength over the reference alloy, Ti-48Al-2Mn-2Nb. The influence of the difficulty of slip transfer between gamma and alpha 2 has been assessed as one of the factors limiting ductility. Regions which are low in aluminium, which are present in the atomised powders initiate fracture at very low strains. These results are discussed in terms of the factors that control the strength and fracture behaviour of TiAl-based alloys.