Contributions of carbon permeation and graphite nucleation to the austenite dusting reaction: A study of model Fe–Ni–Cu alloys

Model Fe–Ni–Cu alloys containing 20–80 wt% Ni and 0, 5 or 10 wt% Cu were subjected to coking and dusting in a 68% CO–31% H2–1% H2O gas mixture (carbon activity, aC = 33, pO2pO2 = 7.1 × 10−26 atm) at 650 °C. Pure nickel and Ni-(5 and 10 wt%) Cu alloys were also investigated as a comparison. Carbon uptake rates on binary Fe–Ni varied in a complex way with alloy composition, reflecting changes in measured alloy carbon permeability. Additions of copper slowed both carbon uptake and metal dusting rates. However, at copper levels exceeding the solubility limit, dusting was accelerated. The effects of copper are attributed to alterations to the graphite precipitation process.

► Carbon uptake rates on binary Fe–Ni depend on carbon permeability of the alloy. ► Copper additions to Fe–Ni reduce the rates of carbon uptake and metal dusting. ► The beneficial effect of copper is attributed to inhibition of graphite nucleation/growth.