It was concluded that crystals with initial orientations which were close to <001> and <011> deformed mainly via glide on the {111}<011> systems. Crystals with orientations near to <111> deformed via glide on {100}<011> systems. The nucleation of misfit dislocations at temperatures greater than 850C relaxed the internal coherency stress that was associated with lattice mismatch between γ and γ' phases. This eliminated the activation of a/6<112> partial dislocations. A contribution of a/6<112> partial dislocations to deformation at temperatures below 850C, and strains greater than 10%, was related to the formation of mechanical twins which resulted in {111}<11¯2> displacements. On the other hand, the maximum strains which were associated with twins were much smaller than the measured creep strain.

Implications of Dislocation Micromechanisms for Changes in Orientation and Shape of Single Crystal Superalloys M.G.Ardakani, R.N.Ghosh, V.Brien, B.A.Shollock, M.McLean: Scripta Materialia, 1998, 39[4-5], 465-72