Nano-indentation was undertaken near grain boundaries to increase understanding of their individual contributions to the material’s macroscopic mechanical properties. Prior work with nano-indentation in body-centered cubic (bcc) materials has shown that some grain boundaries produce a “pop-in” event, an excursion in the load–displacement curve. In the current work, grain boundary associated pop-in events were observed in a Fe–0.01wt%C polycrystal (bcc), and this was characteristic of high resistance to intergranular slip transfer. Grain boundaries with greater misalignment of slip systems tended to exhibit greater resistance to slip transfer. Grain boundary associated pop-ins were not observed in pure copper (face-centered cubic) or interstitial free steel with about 0.002wt%C (bcc). Additionally, it was found that cold work of the Fe–0.01wt%C polycrystal immediately prior to indentation completely suppressed grain boundary associated pop-in events. It was concluded that the grain boundary associated pop-in events were directly linked to interstitials pinning dislocations on or near the boundary. This corresponded well with macroscopic Hall–Petch effect observations.

Nanoindentation Study of Slip Transfer Phenomenon at Grain Boundaries. T.B.Britton, D.Randman, A.J.Wilkinson: Journal of Materials Research, 2009, 24[3], 607-15