Dislocation processes in precipitate-free zones in NIMONIC PE16 studied by in situ transmission electron microscopy

Precipitate-free zones along the grain boundaries cause softening of γ′-particle-strengthened polycrystalline NIMONIC PE16, a nickel-based superalloy containing Ni, Fe, Cr, Mo, Al, and Ti. The relevant dislocation processes were studied by means of in situ straining experiments in a transmission electron microscope. During easy and frequent cross-slip events, numerous dislocation sources are activated, which cause very localized dislocation pile-ups. These facilitate the penetration of dislocations into the interior of the grains.