Electron microscopy and atom probe tomography of nanoindentation deformation in oxide dispersion strengthened steels

30 July 2020
Professor David Armstrong and Professor Michael Moody
ebsd map section of the 100 indents showing a bimodal grain structure

Oxford Atom Probe set out to the extent of any direct link in an Oxide Dispersion Strengthened Steel sample between the Y-Ti-O dispersion and nanoindentation hardness, using electron backscatter diffraction, transmission electron microscopy (TEM) and atom probe tomography (APT).  

 

The local Y-Ti-O distribution did not correlate strongly with the nanohardness, indicating that the dominant hardening mechanisms were at best only weakly related to the Y-Ti-O distribution.  Instead, scanning TEM and APT confirmed that the dominant hardening mechanism was due to the grain boundary refinement, and was further enhanced by tungsten enrichment to ~3.5 at.% at grain boundaries.

 

You can read the full paper in volume 167 of Materials Characterization.