Investigating high temperature liquid E-GaInSn metal-induced corrosion in structural alloys for advanced nuclear reactors

Liquid metals are attractive candidates for primary and secondary coolants in advanced nuclear reactor systems owing to their superior thermophysical properties. However, their interaction with structural materials remains a critical challenge for long-term reactor operation. Gallium-based coolants, particularly eutectic Ga–In–Sn (E-GaInSn), have gained attention in advanced reactor designs, including the MARVEL microreactor under development at Idaho National Laboratory (INL). In this study, the corrosion behavior of three candidate structural alloys—Haynes 230 (H230), Haynes 282 (H282), and austenitic stainless steel 316H—was systematically evaluated during static immersion in E-GaInSn at 500 °C for exposure durations up to 1700 hours. The post-test characterization using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) revealed alloy-specific corrosion mechanisms. All alloys developed surface-localized reaction layers with a periodic layered structure (PLS), consisting of alternating intermetallic phases formed between Ga and alloying elements such as Ni, Cr, Mo, and Fe. The formation of these intermetallic layers confirmed that alloying reactions govern the corrosion process. The thickness, morphology, and distribution of reaction layers were strongly dependent on alloy composition, with H282 showing the greatest resistance compared to H230 and 316H. Notably, corrosion was largely confined to the near-surface region, without significant elemental diffusion or intergranular attack. These results advance the understanding of liquid metal compatibility and highlight the role of alloy chemistry in dictating corrosion resistance. The findings provide essential guidance for material selection and long-term performance assessment of structural components in next-generation nuclear reactor systems.