Corrosion of Inconel 713 Alloy in an Ar-1% SO₂ Atmosphere between 800 and 1100 °C

The Ni-based superalloy, Inconel 713, was corroded between 800 and 1100 °C for up to 100 h in an Ar-1% SO₂ atmosphere. It displayed good corrosion resistance, because the corrosion progressed mainly via oxidation rather than sulfidation. The corrosion products were α-Al₂O₃, Cr₂O₃, TiO₂, NiO, NiAl₂O₄, and NiCr₂O₄. Sulfur was sometimes weakly segregated around the scale-alloy interface. Preferential oxidation occurred along the grain boundaries of the matrix. Except in these areas, uniform oxidation occurred, forming thin scales. The formed scales were prone to spallation.