Mechanistic study of incipient corrosion for nuclear grade lean-Cr FeCrAl alloys in a simulated PWR environment

Abstract

This study systematically investigated the incipient corrosion behavior of Fe-13Cr-4.5Al (wt%) and lean-Cr (7–10 wt%) with 5Al (wt%) FeCrAl alloy with a timescale of 4 months under simulated PWR conditions (18.6 MPa and 360 °C) in an autoclave system. The corrosion induced two types of structure of oxide scale. FeCrAl alloys corroded for 3 months exhibited a duplex structure containing outer oxide particles and an inner Cr-rich spinel. During the corrosion test lasting 3–4 months, a triplex structure containing outer oxide particles, an inner compact Cr-rich spinel layer, and a porous spinel layer was observed. Moreover, Cr enriched at the periphery of outer oxides, indicating the formation of FeCr2O4 spinel oxide.