Corrosion behavior of TA16 titanium alloy during long-term exposure in simulated water environment of small modular reactor

The corrosion behavior of a TA16 titanium alloy during exposure in simulated water environment of small modular reactor (SMR) at 320°C for up to 5000 h was investigated by employing dedicated microstructure characterization. The corrosion weight gain curve of the alloy is found to follow a parabolic law with an exponential parameter of n = 0.738. Oxide scales formed on the alloy surface generally show a two-layer structure composed of a relatively compact inner layer (dense oxide layer) and a discontinuous outer layer (microcrystallites). The dense oxide in the inner layer corresponds to anatase TiO2 while the surface microcrystallite layer is mainly comprised of ilmenite FeTiO3. The number and size of the microcrystallites in the outer layer gradually increase with the exposure time. Fe ions from the corroded loop pipe materials should have participated in forming the outer layer. The compact inner layer is thickened gradually with the test time with its thickness growth curve featured by l = 4.245t0.588, which could better reflect the corrosion behavior of the TA16 alloy.