Impurities segregation and two-dimensional phases formation on iron surface

V.V. Tshigolev

I. M. Frantsevich Institute for Problems of Materials Science of the NAS of Ukraine, Krzhizhanovsky str., 3, Kyiv, 03142, Ukraine
Modern Problems in Physical Materials Science - Kiev: Frantsevich Institute for Problems of Materials Science NASU, 2007, #16


Surface segregation kinetics of impurities in ferritic steels with ultra-low carbon content in temperature range of 550-750oС is studied with Auger-electronic spectroscopy and scanning electronic microscopy methods. At temperatures below 600oС main impurity segregating is carbon displacing the sulfur atoms in surface. Above 700 oС sulfur and titanum dominate displacing phosphorus atoms in the surface. At 600-700oС temperature range sulfur and phosphorus atoms competition is observed and surface composition is found to be different for various granules. Dissolution of titanium sulfides placed in subsurface layers of some granules increases segregation flow of sulfur and titanium atoms and decreases phosphorus segregation. The surface of granules free of sulfide releases is enriched with phosphorus.