Characterizing faulted dipoles in TiAl with electron microscopy and computed image simulations

The low temperature deformation microstructure of TiAl is dominated by the presence of stacking fault dipoles [I]. Two different faulted dipole geometries have been proposed in the literature [2,3], and the existence of both types of faulted dipoles have been verified in the present study with comparisons to computer simulated images. These comparisons suggest that extrinsic stacking faults in TiAl are bounded by single Shockley partial dislocations when the deformation occurs at room temperature and by double Shockley partial dislocations when the deformation occurs at 80 K. This change in the faulted dipole geometry is believed to be related to a change in the activity of the super dislocations that control deformation.