Optical coherence tomography vs. scanning electron microscopy in the assessment of the different types of fractures of metallic materials - in the frame of COST Action 21159 PhoBioS

We report on our on-going research on topographic investigations of the fractures of metallic materials. We demonstrated in a first study that Optical Coherence Tomography (OCT) can successfully replace the gold standard of scanning electron microscopy (SEM) in assessing brittle versus ductile metallic fractures for certain materials. A second study has approached a larger range of metallic materials, but also the most common type of fatigue fractures, which are responsible for more than 90% of all fracture-based incidents. The necessary lateral resolution of 4 microns for OCT is demonstrated to allow for an optimal assessment of the type of fracture of a certain material (subjected to a specific type of testing). In contrast, a lower (but more common) lateral resolution of 10 microns raise issues in the envisioned assessments. On-going investigations in the frame of COST Action 21159 (PhoBioS) are presented. In conclusions, although SEM resolution is three orders of magnitude better than OCT resolution, we have demonstrated that OCT is good enough to distinguish between different types of fractures.