Influence of different texture aspects on creep properties of a fully lamellar Ti-47Al-2Cr-2Nb alloy

The texture-stress-creep relationships have been evaluated in this two-phase alloy of composition Ti-47Al-2Cr-2Nb (at%) with a fully lamellar microstructure. We have performed a number of mechanical tests on appropriately oriented specimens that have confirmed the texture behavior already assessed in PST-single crystals. This mechanical data base has been used successfully for the interpretation of deformation modes in a fully lamellar microstructure. Additionally, varying the cooling rate was found to significantly alter the decomposition modes of the high-temperature alpha phase, yielding different gamma/gamma interface type distributions. We will review TEM observations highlighting three different mechanisms occurring at different temperature ranges. The related microstructural development made relevant statistical studies of the distribution of individual lamellae to be carried out for the interpretation of lamellar phase transformations. This work aimed at determining if the different sequences of lamellar interfaces would play a significant role in measuring the creep properties in lamellar TiAl-based alloys.