Grain Boundary Pop-in
indents in Fe

Nano-indentation near grain boundaries can exhibit very large 'pop-ins' or displacement bursts on the load-displacement curves. The phenomenon has been seen in bcc metals containing interstitials (carbon and/or nitrogen). Lowering the interstitial content, or increasing the dislocation density so that there are not enough interstitials to pin all dislocations removes the grain boundary pop-in effect.

The pop-in allows the resistance to slip transfer (K) to be assessed at individual grain boundaries. We have used this to show that K increases with misalignment of slip systems in the two grains at the boundary.
gb strength
Fe gb pop_in

 

Contact: Angus Wilkinson or Ben Britton

A nanoindentation study of slip transfer phenomenon at grain boundaries
TB Britton, D Randman, and AJ Wilkinson
J. Materials Research, (2009), vol. 24, 607-614
doi:10.1557/JMR.2009.0088