Corrosion Behavior of Structural Materials in Liquid Metal Environments

In advanced energy and nuclear systems, liquid metals such as lead, lead–bismuth eutectic and molten salts offer exceptional heat transfer and low neutron moderation, making them attractive coolants. However, their chemical reactivity poses significant challenges for structural components. Corrosive interactions manifest through oxide scale formation, selective leaching of alloying elements and internal oxidation, all of which can degrade mechanical performance. In oxygen-controlled environments, protective oxide layers may form, yet their stability depends critically on temperature, oxygen potential and alloy composition. Under stagnant conditions, diffusion of chromium and aluminium governs the development of duplex oxide scales, while turbulent flow accelerates mass transfer and can erode protective films, leading to flow-accelerated corrosion. Liquid metal embrittlement and thermal cycling further complicate material longevity. Contemporary research focuses on alloy design for self-healing oxides, advanced ferritic-martensitic steels and FeCrAl alloys, as well as novel ceramic and high-entropy coatings. A detailed understanding of microstructural evolution under operational conditions is essential to ensure reliability in Generation IV reactors, concentrated solar power systems and accelerator-driven facilities worldwide.

Research from Nature Portfolio

Recent studies have elucidated the nanoscale mechanisms of oxidation on martensitic steels in liquid lead–bismuth eutectic. High-resolution microscopy has revealed an internal oxidation zone beneath a duplex oxide scale, driven by both micron-scale and nano-scale diffusion of chromium. This dual diffusion mechanism accounts for the progressive growth of inner oxide layers and the transformation of the subsurface zone into a consolidated protective barrier. The refined oxidation model reconciles previous discrepancies between theory and experiment, offering guidance for alloying strategies that enhance scale adhesion and suppress internal oxidation in reactor environments.

Corrosion Behavior of Structural Materials in Liquid Metal Environments publication trend

The graph below shows the total number of articles in corrosion behavior of structural materials in liquid metal environments across all publications each year (not limited to Nature Index journals).

Technical terms

Liquid lead–bismuth eutectic (LBE): A low-melting alloy of lead and bismuth used as a coolant in advanced reactors.

Internal Oxidation Zone (IOZ): A subsurface region where oxygen penetrates an alloy, forming oxide particles beneath the surface layer.

Duplex oxide scale: A two-layer oxide structure comprising an outer iron-rich layer and an inner chromium-rich layer.

Flow-Accelerated Corrosion (FAC): Corrosion intensified by fluid dynamics, where turbulent flow enhances mass transfer and metal dissolution.

FeCrAl alloys: Iron–chromium–aluminium alloys engineered to form stable, protective alumina scales at elevated temperatures.

References

1. Oxidation mechanism of T91 steel in liquid lead-bismuth eutectic: with consideration of internal oxidation. Scientific Reports (2016).
2. A Review of the Surface Modifications for Corrosion Mitigation of Steels in Lead and LBE. Coatings (2021).
3. Flow-Accelerated Corrosion of Type 316L Stainless Steel Caused by Turbulent Lead–Bismuth Eutectic Flow. Metals (2018).
4. Corrosion Studies of Low-Alloyed FeCrAl Steels in Liquid Lead at 750 °C. High Temperature Corrosion of Materials (2019).