SIMS/XPS studies of surface layer formed in Fe-Si-Mn alloys by oxygen penetration

Secondary ion mass spectrometry (SIMS) and X-ray photoelectron spectroscopy (XPS) have been used for analyzing surface layers formed in Fe-Si-Mn alloys containing 1, 2, 3 and 4.5 mass% silicon, which were annealed in hydrogen and argon gases with a low partial pressure of oxygen. SIMS depth profiles showed that silicon in these alloys is reacted with oxygen penetrating into the bulk to form silicon oxides, and the characteristic distribution of silicon oxides is obtained the surface layer, depending on the bulk silicon concentration. Manganese in the alloys was also found to be enriched to the outer side of the surface layer. On the other hand, XPS results showed that silicon and manganese are enriched on the top surface in these alloys, and the surface concentration of these elements depends on the bulk silicon concentration.