Microstructure Evolution of Magnetite Layer on CLAM Steel Exposed to Lead-Bismuth Eutectic Containing 10−6 Wt% Oxygen at 500 °C

The microstructure evolution of the magnetite layer on CLAM steel in lead-bismuth eutectic containing 10 (-6) wt% oxygen at 500 & nbsp;C was investigated. From 500 to 20 0 0 h, magnetite first changed from many islands to an intact and continuous oxide layer, which then fell off and regenerated; its main microstructure changed from Cr-containing powders to Cr-free crystals. The formation of island magnetite may be related to the enrichment of W in the spinel layer and the large size and poor uniformity of martensitic laths. Finally, an island growth, exfoliation and regeneration model of the magnetite layer is proposed based on the above phenomenon. (C)& nbsp;2022 Elsevier B.V. All rights reserved.