The {111} antiphase-boundary energies, Γ, of the L12 long-range ordered γ’ phases that precipitation-strengthened commercial Ni-based superalloys (Nimonic PE16, Nimonic 105) were measured by using 3 independent methods. Firstly, it was found from the dependence of the critical resolved shear stress upon the dispersion of the γ’ precipitates. Secondly, it was found from the minimum sizes of the Orowan dislocation loops which could be sustained by γ’ precipitates. Thirdly, it was found from the separations of the super-partial dislocations which bounded antiphase boundary faults in single-phase γ’ alloys. The latter method was based upon state-of-the-art transmission electron microscopic investigations, and was considered to be the most direct. The results which were determined by using the 3 methods were (with one exception) in satisfactory agreement.

Three Alternative Experimental Methods to Determine the Antiphase-Boundary Energies of the γ′ Precipitates in Superalloys. D.Baither, C.Rentenberger, H.P.Karnthaler, E.Nembach: Philosophical Magazine A, 2002, 82[9], 1795-805