Deformation microstructure of Nb-modified TiAl intermetallics Ti54A16Nb at ambient temperature

Annealed Ti54A16Nb samples have been deformed in compression at ambient temperature to a strain of 6%, and examined using transmission electron microscopy. A high density of a/2<110] single dislocations and an appreciable amount of a〈011] perfect superdislocations were characterized. No stacking fault dipoles or dissociated superdislocation partials were observed. This was attributable to the modifying effect of Nb on the covalent nature and stacking fault energy of TiAl. The insufficient number of active slip systems in the alloy were thought to be responsible for the inhomogeneous deformation and the brittleness of the alloy.