Core structure of a<100> interfacial superdislocations in a nickel-base superalloy during high-temperature and low-stress creep

Dislocation substructures were investigated in a nickel-base single crystal superalloy subjected to 85 h creep at 1100 °C and 130 MPa using conventional and high resolution transmission electron microscopy. Both hexagonal and square-like interfacial dislocation networks were observed. The square-like networks, which were caused by two perpendicular sets of a/2<110> dislocations forming a[100] superdislocations, were tested. It was concluded that the a[100] interfacial dislocation occurred in the form of a dislocation dipole. The creation and destruction of dislocation dipoles proceeded reversibly via a slip-and-climb mechanism.