Dislocation Mechanisms during High Temperature Creep Experiments on MC2 Alloy
The creep behaviour of MC2 single crystal superalloy has been studied at 1150°C/80 MPa, with an applied load along  axis. The resulting dislocation microstructures were examined by transmission electron microscopy. The occurrence of a type dislocations (with a zero Schmid factor) within the ordered γ' precipitates is often observed. It is shown that those dislocations moved by a climb process, based on a mechanism involving two dislocation systems and vacancy exchanges, as proposed in the literature. We calculate the vacancy fluxes associated with such a mechanism and show that the vacancy transportation can be easily insured by a simple diffusion process. This calculation shows that the diffusion and climbing steps do not seem to be the creep rate controlling mechanisms for those situations in MC2 alloy.
F. Touratier et al., "Dislocation Mechanisms during High Temperature Creep Experiments on MC2 Alloy", Advanced Materials Research, Vol. 278, pp. 7-12, 2011