Single crystals of Ni-44at%Al alloy were studied following compressive deformation, in the hard orientation, between 700 and 825K. In order to understand the mechanism of the slip transition which occurred at intermediate temperatures, compression was performed using various strain rates and various strain levels. Local decomposition of a<111> dislocations was observed between 750 and 800K. At 800K (the slip transition temperature), complete decomposition occurred into a<101> and a<010> dislocations. Several unique features were associated with this decomposition: such as a preference for near-edge line directions (for a<111> dislocations), significant strain-softening between 800 and 900K and an effect of thermal activation in determining the extent of the decomposition event.

The Mechanics of Slip Transition at Intermediate Temperatures in <001>-Oriented NiAl Single Crystals - I. Experimental Observations of the Decomposition of a<111> Dislocations in Ni-44at%Al. R.Srinivasan, J.Brown, M.S.Daw, R.D.Noebe, M.J.Mills: Philosophical Magazine A, 2000, 80[12], 2841-54