How Mn and Ti Promote Metal Dusting in NiCu Alloys

ABSTRACT Metal dusting is a critical corrosion phenomenon in industrial processes using carbonaceous gases and high temperatures. Cu can suppress metal dusting when added in sufficient amounts to pure Ni. In this study, metal dusting attack on Monel® 400 alloy (Ni with 29–30 wt.% Cu, 1 Mn wt.%, and 1–2.5 wt.% Fe) processed via additive manufacturing (AM) was investigated in detail. To determine the role of Mn and Ti in the metal dusting attack, AM Monel® 400 without Mn, with higher Mn content (2 wt.% Mn), and with TiN nanoparticles were examined and compared to Ni70Cu30 and Ni69Cu30Mn1 model alloys. Increasing Mn content or adding TiN promoted mass gain mainly through carbon uptake and graphite precipitation. The catalytic roles of Mn and Ti oxide in carbon uptake are discussed in detail. In this metal dusting attack, oxidation, catalysis, carbon dissolution, carbon diffusion, and carbon precipitation play a significant role and drive the degradation depending on the alloy composition.