This research examines mechanisms of plastic deformation in titanium aluminide intermetallic alloys, TiAl (gamma) and Ti3Al (alpha 2), over a wide range of temperature and strain rates. Factors that influence dislocation mobilities are identified so that mechanisms that contribute to plastic flow can be determined. Two models for dislocation mobility are investigated: one looking at anisotropy of bonding charge densities and its relationship to dislocation mobility; the other at the role of non-planar dislocation core configurations on dislocation mobility. A third component of the study examines the variation in critical resolved shear stresses of various dislocations taken from a number of potential slip systems. This involves the fabrication of single crystals so that stress can be applied along specific crystallographic directions. Experimental techniques include transmission electron microscopy and high resolution electron microscopy. %%% This research adds to the fundamental knowledge concerning mechanical deformation of intermetallic alloys. It is relevant to the future development of ductile, strong intermetallic alloys for operation at high temperatures in applications such as jet engines.
