The development of dislocation configurations in two single-crystal superalloys during high-temperature low-stress creep (1100C, 137MPa) was investigated with the use of transmission electron microscopy. Detailed analysis showed that the lattice misfit has an important influence on the dislocation movement. For an alloy with a large negative lattice misfit, the dislocations were able to move smoothly by cross-slip in the horizontal γ channels. During subsequent formation of γ/γ′ rafted structure, the dislocations on the surface of γ′ cuboids rapidly re-orientate themselves from <110> to <100> direction and form a complete network. For an alloy with a small lattice misfit, the dislocations move by the combination of climbing and gliding processes, and the resultant γ/γ′ interfacial dislocation network was incomplete. A good explanation of the creep curves was obtained from these differences in the microstructures.

The Effect of Lattice Misfit on the Dislocation Motion in Superalloys during High-Temperature Low-Stress Creep. J.X.Zhang, J.C.Wang, H.Harada, Y.Koizumi: Acta Materialia, 2005, 53[17], 4623-33