The weak-beam method of transmission electron microscopy was used to measure the dissociation width of superlattice dislocations in Ni3(Al,Ti) as a function of temperature. Dislocations in thin foils parallel to (111) and (010) planes were investigated. No significant variation of the distance between the unit dislocations which constitute the superlattice dislocation was found over the temperature range from 298 to around 950K. The experimental observations were discussed in the framework of the model proposed by Brown. It was based on the transformation of geometrical antiphase boundaries into antiphase boundaries in their thermodynamic equilibrium configuration. The role of this antiphase boundaries antiphase boundary-based model was examined with respect to the anomalous increase of the flow stress with increasing temperature.

Weak-Beam Study on Superlattice Dislocations in a Ni3Al Alloy in the Temperature Range of the Flow Stress Anomaly. Korner, A.: Philosophical Magazine Letters, 1989, 59[1], 1-7