The fluctuation of short-range order evidenced by mobile dislocations in the γ-phase of a nickel-based superalloy

The analysis of the distribution of moving dislocations is used to obtain the energy associated with the short-range order (SRO) present in the γ-phase of a nickel-base superalloy. This energy is evaluated at different spatial points within the sample when the dislocations propagate at 25 °C and at 350 °C. An accurate calculation reveals a clear spatial fluctuation of this energy over several micrometers. The SRO thus acts as a non-uniform obstacle with (i) soft areas extending over several micrometers where the nucleation of dislocation sources is enabled and (ii) hard ones where dislocation pile-ups need to be crossed through.