Incipient corrosion of FeCrAl alloys in H₃BO₃- and LiOH-containing pure water at 360 °C and 18.5 MPa

The demand of accident tolerant fuel cladding materials provides a momentum for the development of FeCrAl alloys. To prove its potential, this work studied the corrosion behavior of FeCrAl alloys in H₃BO₃- and LiOH- containing water at 360 °C and 18.5 MPa for 500 h. XPS, XRD, SEM, Raman and AFM analyses were employed to identify oxide films, and the early corrosion mechanism of FeCrAl was discussed. Duplex oxide films were found on the surface of FeCrAl. The inner layer was Fe-Cr-Al spinel, and the outer crystals was dominantly composed of Fe₂O₃, accompanied by Fe₃O₄, FeCr₂O₄, NiFe₂O₄ and Li₂Fe₃O₄. Similar to FeCrAl, Zircaloy-4 showed negligible weight change. However, its surface corrosion was more severe, and the oxides formed were mainly ZrO₂ and Zr₃O_1-X. Li₆Zr₂O₇ and other sub oxides were also observed.