Cross-slip and dislocation climb in nickel-base superalloys

An investigation of the minimum creep rate of two nickel-base superalloys, with low volume fraction of precipitates γ′ has shown that two mechanisms were operative at the temperatures 923 and 973 K and an extensive range of applied stresses. The experimental data were interpreted in terms of a new constitutive equation based on a creep model involving dislocations cross-slip in the matrix and dislocation climb at high stresses over the strengthening phase. This analysis has been used to obtain microstructural parameters involved in the model such as activation area and stacking fault energy. The apparent activation energy, ΔHap, measured by abrupt and small changes in temperature were analyzed.