A Si-containing, high-temperature alloy (Fe-17Cr-9Ni-8Mn-4Si) was exposed to high-carbon activity and low-oxygen partial pressure environments (CO-H 2 ) over a temperature range from 650 to 950°C. No metal dusting corrosion was observed in this alloy. The structure and composition of the surface films formed were characterized in detail at the nanometer level. At a temperature of 650°C, the surface-oxide films formed are made up of an inner, continuous, amorphous-silica (SiO 2 ) layer and an outer crystalline manganese chromate (MnCr 2 O 4 ) spinel layer with manganese oxide (MnO) crystals on the surface. By contrast, at a higher temperature of 950°C, a more-complex layered structure is developed, comprising inner, continuous, amorphous SiO 2 and crystalline manganese-silicate (Mn 2 SiO 4 ) layers and an outer crystalline Cr 2 O 3 /MnCr 2 O 4 duplex layer with MnO crystals having variable textures on the surface.