An electron microscope study of mechanical twinning and fracture in TiAl alloys

Deformation twinning is an important mode of plastic deformation in γ(TiAl)-based titanium aluminide alloys. The paper describes conventional and high-resolution electron microscope investigations of twinning arrangements in γ-based titanium aluminide alloys. The major areas of study are: (i) twin nucleation and propagation, (ii) effects of solutes and precipitates on the kinematics and dynamics of twin propagation, (iii) association of mechanical twinning and fracture. The implications of the results will be discussed with respect to alloy design strategies towards improved mechanical properties.