The effects and mechanisms of pulsed magnetic field treatment on the corrosion resistance at phase boundaries in cobalt‐based alloys

Abstract The corrosion resistance of cobalt‐based alloy cladding layers is crucial for the long‐term reliability of materials in the nuclear power industry, where they are exposed to highly aggressive environmental conditions. A major challenge to their performance is the corrosion occurring at phase boundaries under harsh operating conditions. This study investigates the effects of pulsed magnetic field treatment (PMT) on improving corrosion resistance at phase boundaries, specifically at the carbide/matrix Co interface, and seeks to clarify the underlying mechanisms. Advanced characterization techniques, including scanning electron microscopy (SEM), in situ transmission electron microscopy (TEM), in situ scanning kelvin probe force microscopy (SKPFM), and density functional theory (DFT) calculations, were employed. PMT samples exhibited no interface corrosion cracking or carbide spalling and showed a significant reduction in corrosion depth. TEM analysis revealed reduced lattice distortion at phase boundaries and a partial transformation of face‐centered cubic (FCC) Co to hexagonal close‐packed (HCP) Co. The enhanced corrosion resistance at phase boundaries is attributed to changes in the electronic work function (EWF), as determined by SKPFM measurements and DFT calculations.