Deformation and fracture characteristics in TiAl at room temperature and 800 °C

The characteristics of deformation and fracture at room temperature and 800 °C of a binary (γ-α2)-Ti-48 at.%Al intermetallic with a duplex microstructure have been identified by scanning and transmission electron microscopy (SEM and TEM). A change in the predominant fracture mode from transgranular at room temperature to intergranular at 800 °C has been observed which coincided with profoundly different plastic behavior of the α2-phase. The α2-lamellae exhibited only localized planar slip of 〈a〉 dislocations during room temperature deformation, whereas at 800 °C 〈a〉 dislocations are activated more generally, and in addition motion of 〈c〉-component dislocations has been implied. The γ-TiAl phase deformed by ordered twinning and slip of both ordinary and superdislocations during loading at both temperatures.