T91 samples were exposed to static liquid lead-bismuth eutectic (LBE) at
700{\deg}C for 250-500 hours in either an oxidising or reducing environment.
Corrosion damage was characterised using electron microscopy techniques, which
identified networks of LBE intrusion beneath LBE-wetted surfaces. Under
reducing conditions these networks are uniformly distributed, while they appear
patchier and deeper under oxidising conditions. The individual intrusions
preferentially follow microstructural features, initially along prior-austenite
grain boundaries, followed by penetration down martensite lath boundaries.
Local depletion of Cr was observed within 4 {\mu}m of the intrusions and along
intersecting boundaries, suggesting local Cr dissolution as the main corrosion
mechanism.Comment: 14 pages, 4 figures and graphical abstract, submitted to Scripta
Materiali