Active deformation mechanisms responsible for ductility and flow stress dependence on temperature in TiAl alloys

Abstract
The active dislocation mechanisms responsible for the deformation process of two phase TiAl alloys have been analysed and their influence on ductility and strength have been interpreted as a function of deformation temperature. The measured values of misfit strain between the α₂ and the γ phases have been shown to be responsible for the accumulation of dislocations that occurs at their interfaces. The stress concentrations that build up at these sites lead to microcrack formation and determine the lack of ductility of the materials. The anomalous strengthening effect that is observed with increasing temperature has been shown to be determined by the activity of ordinary 1/2<[110] dislocations that are generated from twin intersections. The increased jog density produced by the increased number of emitted dislocations up to the peak temperature leads to the strengthening mechanism observed.