Enhancing corrosion resistance and radiation shielding of AISI 304 SS with Nb and Mo-added Al0.3CrFeCoNi-based high-entropy alloy coatings in 3.5 wt% NaCl: The effect of environmental temperature

In this study, the corrosion behavior and radiation shielding capacity of Al 0.3 CrFeCoNi-based high-entropy alloy coatings (HEACs) produced by high-speed laser metal deposition (HS-LMD) were investigated. The addition of Nb and Mo elements in critical ratios was also evaluated under 3.5 wt% NaCl conditions to assess their potential in nuclear applications. Electrochemical corrosion tests were conducted using potentiodynamic scanning (PDS) and electrochemical impedance spectroscopy (EIS) at 25, 50, and 75 °C. The phase structure of the coatings was characterized using X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Microstructural observations before and after the corrosion tests were performed with scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The radiation shielding capacities of the coatings were assessed by comparing linear attenuation coefficient (LAC), half-value layer (HVL), and mean free path (MFP) values. The results revealed that adding Nb and Mo maintains the FCC phase structure after the cladding process. Corrosion tests indicated that the Mo-containing coating had the lowest corrosion rate of 0.59 μm·year −1 at 25 °C, while the highest rate of 13.31 μm·year −1 was observed in the Nb-containing coating at 75 °C. Furthermore, the Mo-containing coating demonstrated superior corrosion resistance, supported by EIS and XPS analyses that highlight the role of MoO 3 and MoO 2 in enhancing passivation stability. Radiation shielding evaluations show that the Al 0.3 CrFeCoNiMo 0.75 structure has the highest LAC of 4.828 cm −1 , attributed to density and atomic number of Mo, while the MFP value decreased to 0.207 cm, indicating enhanced photon attenuation. These results emphasize the potential of Al 0.3 CrFeCoNi-based HEACs as effective materials in radiation and corrosion-heavy environments. • Nb and Mo additions preserved the FCC phase and formed hard Laves and μ-phases, enhancing coating properties. • Mo-containing HEACs showed superior corrosion resistance, with the lowest rate of 0.59 μm/year at 25 °C. • Microstructural analysis revealed unmelted particles and porosities as critical points for corrosion initiation. • Mo-rich coatings exhibited improved hydrophobicity and passivation stability, enhancing corrosion protection. • Mo-containing coatings achieved the highest radiation shielding with an LAC value of 4.828 cm −1 .