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The present study investigated the dissolution and oxidation corrosion behaviors of Hastelloy exposed to static liquid lead‐bismuth eutectic (LBE) at 500°C with an oxygen concentration of 1 × 10−6 mass%. Hastelloy exhibited better LBE corrosion resistance than the Monel alloy. Both dissolution and oxidation corrosion were observed in Hastelloy, and the maximum LBE penetration depth and spinel layer thickness in the corroded sample after 4000 h of exposure reached 120 ± 36 and 21 ± 12 µm, respectively. Annealing twin boundaries provided favorable paths of accelerated LBE penetration into the matrix, resulting in selective leaching of Ni. Microstructural characterization revealed that the spinel layer formed between penetrated LBE and base metal slowed down the elemental interdiffusion, thereby retarding the dissolution rate. Volumetric changes induced by LBE penetration promoted the formation of stacking faults and dislocations, which could provide more channels for elemental diffusion, leading to the propagation of dissolution attack. [ABSTRACT FROM AUTHOR]

Clarification of the relationship between oxygen diffusion and microstructural evolution in liquid lead-bismuth eutectic (LBE) is of great importance for understanding and consequently tailoring the oxidation process. In the present study, a Si-modified ferritic martensitic steel was exposed to oxygen-saturated LBE at 500°C at various times and the interface between the internal oxidation zone and matrix was investigated. Microstructural characterisation reveals that grain boundaries and martensitic lath boundaries provide a fast pathway for oxygen diffusion, resulting in the high amount of oxidation products, as well as cracks. The internal stress caused by the formation of oxidation products along grain boundary results in the proliferation of dislocations, which subsequently play as the new diffusion channel for oxygen. The chemical analysis demonstrates that Si preferably concentrates along the dislocations in a form of Si-rich oxide, suggesting the oxidation of Si is prior to the Cr-rich oxide. [ABSTRACT FROM AUTHOR]