Effects of structural relaxation and crystallization on the corrosion resistance of an Fe-based amorphous coating

An Fe48Cr15Mo14C15B6Y2 amorphous coating was fabricated using high-velocity oxygen fuel (HVOF) technology. The obtained coating was annealed at 500 degrees C and 700 degrees C to induce structural relaxation and crystallization, re-spectively. Then, the influences on the coating ' s corrosion resistance were investigated. The results demonstrate that the corrosion resistance of the coating is enhanced after structural relaxation, which can be attributed to the higher stability of the passive film. In contrast, the corrosion resistance of the coating is deteriorated after crystallization because the formation of crystals of chromium carbides may decrease the stability of the passive film and result in Cr-depleted zones where they could be easily attacked by pits, especially at the interfaces and junctions of the droplets.