Metal dusting corrosion of nickel-based alloys

Metal dusting corrosion of nickel-based alloys (i.e., Inconel 600, 601, and 693) has been simulated in high-carbon-activity environments over a temperature range of 450-750°C. Overall, Ni-based alloys corrode by a combination of carbon diffusion and precipitation in the alloy interior and atom migration through surface carbon deposits. The formation of protective surface oxide films provides initial protection against metal dusting, but local rupture of surface Cr-rich oxide films allows rapid carbon diffusion into the alloy. The focus of this research was to advance the understanding of the corrosion mechanisms of Ni-based alloys by characterizing interfacial processes at the nanometer level. In addition to the effect of temperature and environmental chemistry, the mechanistic aspects of metal dusting are discussed with particular attention to the stages of microstructure evolution as degradation proceeds.