Study of the corrosion of austenitic stainless steel D9 in Lead–Bismuth Eutectic (LBE): Extension of the Available Space Model to a ternary alloy

Corrosion of the austenitic stainless steel alloy D9 by Lead–Bismuth Eutectic (LBE) has been studied by Scanning Electron Microscopy (SEM) and Electron Probe Micro-Analysis (EPMA). D9 samples exposed to LBE for 1000 h, 2000 h, and 3000 h developed thick, bi-layer oxides, whose inner layer consists of iron and chromium oxides (likely spinel-structured) and whose outer layer consists mostly of iron oxides, of magnetite stoichiometry (Fe3O4). Iron was the primary diffusing element and the limiting factor in the growth of the bi-layer oxide. A standard model of the oxide growth process in binary alloys is the Available Space Model (ASM). However, the conventional ASM is a poor model of oxide growth in a ternary alloy such as D9. An extension to the ASM is developed which greatly improves the fit to the oxide growth in D9.