Analysis of dislocation networks in crept single crystal nickel-base superalloy

The creep behaviour at 1050 °C of <001> oriented MC2 single crystals is analysed by means of SEM and TEM observations. The #gamma#–#gamma#′ rafting process occurs rapidly and appears to be correlated with the establishment of a pseudo-stationary creep stage. The regular and stable networks are seen in the (001) interfaces. A detailed analysis of dislocation networks in these (001) interfaces shows that they are constituted by an association of hexagonal and square cells of a/2 <110> dislocations. The square part is unstable and gives rise to the systematic creation of a <001> dislocations included in the misfit dislocation network.