Creep deformation at 740C of various L12 alloys (NiAlTiCr), the compositions of which were based on Ni3Al, were performed. The deformed samples exhibit peculiar extended defects which were identified as superlattice intrinsic stacking faults gliding on parallel and close {111} planes. The 1/3<1121> partial dislocations interact strongly so as to produce a variety of geometrical configurations of the defects. The relative positions of the partial dislocations were determined in transmission electron microscopy by means of contrast simulations of experimental images taken in the two-beam approximation. The experimental positions corresponded to those predicted from the assumptions of mechanical equilibrium using the anisotropic elasticity theory. In the narrow composition range studied, the superlattice intrinsic stacking faults energies derived from such an equilibrium were about 4mJ/m2. They decreased for higher Ti compositions.

Estimation of the Intrinsic Fault Energies of Phases (Ni, Al, Ti, Cr) based upon Ni3Al. Bonnet, R., David, D.: Acta Metallurgica et Materialia, 1991, 39[3], 329-40