Hot corrosion behaviors of directed energy deposited Inconel 718/Haynes 25 functionally graded material at 700? and 900?

The hot corrosion behaviors of directed energy deposited Inconel 718/Haynes 25 functionally graded materials (FGMs) coated with 75% Na2SO4 + 25% NaCl molten salt at 700 ? and 900 ? for 100 h were investigated. The hot corrosion products at different temperatures were characterized by scanning electron microscope (SEM) in gradient direction. The microstructural evolution as well as elemental distribution in layers containing different powder contents were observed by optical microscopy and SEM. The results showed that the columnar grains became equiaxed and smaller with the increase of Haynes 25 content. The hot corrosion resistance in gradient direction was improved due to the increasing of Cr content, narrower grain boundaries and finer grains. In particular, the microstructual evolution and its effect mechanism on hot corrosion resistance were revealed.

Automated summary

The hot corrosion behaviors of directed energy deposited Inconel 718/Haynes 25 functionally graded materials (FGMs) coated with a molten salt mixture were investigated. The results showed that increasing the Haynes 25 content improved the hot corrosion resistance in the gradient direction due to changes in grain size and distribution. The microstructural evolution and its effects on hot corrosion resistance were also revealed.