Dislocation models for anomalous flow in L12 compounds

This paper reports that it is widely accepted that the anomalous flow behavior in L12 compounds is related to a thermally activated core transformation or cross slip which inhibits the motion of screw dislocation on the (111). However, the nature of the cross slip process and its incorporation into deformation models have varied considerably. The present models are critically reviewed in light of the existing experimental evidence, including transient deformation studies and weak beam transmission electron microscopy. It is suggested that development of dislocation substructure is key to a complete representation of deformation in these compounds, even at relatively small strains. The basis of a new model will be presented in which cross slip from (111) to (010) is stabilized, leading to dislocation storage and work hardening. A mechanism is also offered for the dynamic recovery of the dislocation substructure. The qualitative predictions of the model will be discussed in terms of the observed dislocation substructures and the measured monotonic and transient mechanical behavior