Unique Structured Inner Oxide Layers Formed on the Austenitic Ods Steel Exposed to Supercritical Water

The inner oxide layer has been carefully studied in the austenitic ODS steel exposed to supercritical water in this work. A dual-phase structure, including Ni-rich austenitic skeletons and Cr-rich spinel fillers, is widely observed in the inner oxide layer. Additionally, other unique structures, such as Cr/Fe-rich spinel and Cr-rich spinel with corrosion pores, are also found in the inner oxide layer. The formation of these unique structures can be attributed to the effects of (Zr, Ti)O2, Y2O3 or grain boundaries. The size of the precipitates plays a decisive role in the corrosion behavior of the matrix.