Preliminary corrosion studies of P-91 in flowing lead-lithium with and without magnetic field for Indian lead-lithium ceramic breeder test blanket module

To study the corrosion of P-91 (9% chromium and 1% molybdenum) material with lead-lithium (Pb-Li) eutectic, two experiments were carried out in a forced convection loop, at eutectic temperature of 550C. The first experiment was carried out at a velocity of 15cms^-1 for 1000h and the second experiment, at a velocity of 30cms^-1 for 2700h. In both the experiments, P-91 sample coupons were exposed to Pb-Li flow in the presence and absence of magnetic field. Samples were analyzed using an optical microscope, scanning electron microscope (SEM) and electron probe micro-analyzer (EPMA). Micro-Vickers hardness testing was also carried out. Dissolution of elements into liquid metal is the main corrosion mechanism. Iron and chromium were selectively getting leached out from the near-surface region (∼4μm) in the first experiment and molybdenum and manganese were also found leaching from a greater depth in the second experiment. The samples kept in the magnetic field showed a higher corrosion rate (∼320μm/year) as compared with the corrosion rate (∼200μm/year) of the samples kept in non-magnetic field regions. Hardness of the exposed samples was lower than the unexposed samples in both the experiments. Hardness was found to be low in the near-surface region for all the samples in both the experiments.