Electrochemical and hot corrosion analysis of novel AlBeSiTiV light weight HEA coating on SS316

Abstract

Abstract In the realm of advanced materials research, high entropy alloys (HEAs) have emerged as a dynamic and rapidly evolving field, their potential can be further harnessed by developing HEA coatings on specific substrate materials. In this study, equiatomic AlBeSiTiV lightweight HEA (LWHEA) was successfully synthesized through the precise technique of mechanical alloying (MA). Subsequently, this innovative HEA coating was applied to the SS316 substrate using atmospheric plasma spray (APS). The microstructure of the synthesized HEA revealed a prominent FCC phase, with the coating having an average thickness of approximately 150 μm. Notably, the coated and coated annealed samples displayed improved microhardness of 985±13, and 1100±15 HV which was five and six times respectively that of the substrate. Electrochemical and hot corrosion tests were conducted on the substrate, coated, and coated annealed samples. The outcomes shed light on the profound impact of annealing in mitigating the corrosion rate as the porosity of the coated annealed samples was reduced to 2.53% which resulted in a significant reduction in corrosion rate when compared to coated samples. Hot corrosion tests demonstrated mass loss in the substrate due to the formation of iron oxide and subsequent spallation of it while mass gain in the coated and coated annealed samples due to oxide layer formation. Coated annealed samples exhibited lower mass gain in comparison to coated samples, showing reductions of 6% and 3% in Na2SO4/NaCl and Na2SO4/ V2O5, respectively. These findings underscore the immense promise of the annealed coating for applications demanding steadfast protection against corrosive challenges.