Nanoindentation Induced Deformation Near Grain Boundaries of Corrosion Resistant Nickel Alloys

Abstract

The damage accumulation behavior of different grain boundary structures in Inconel 690 (Ni-29wt%Cr-9wt%Fe) was investigated in the presence of large, localized plastic strains induced by nanoindentation. Spatially-resolved hardness was measured as a function of lateral distance from ‘random’ high-angle grain boundaries and twin boundaries. The confinement of induced defects between the indenter tip and grain boundaries did not lead to significant differences in measured hardness between high angle and twin boundaries. Critical “pop-in” loads indicating the onset of incipient plasticity were lower within 1μm of grain boundaries, but were statistically equivalent for random and twin boundaries. These results suggest a comparable extent of dislocation mobility and absorption at the different grain boundary types in Inconel 690 under ambient conditions.