Initial oxidation of TiFe1−xMnx (x = 0-0.3) by low dose exposures to H2O and O2

The very initial room-temperature oxidation processes of the ternary pseudo-binary TiFe1−xMnx (x = 0-0.3) intermetallics by trace amounts of H2O vapor and O2 were studied utilizing XPS and AES techniques. Different reactivities of the two gases were obtained, with a lower oxidation ability of H2O, relative to O2, as anticipated from thermodynamic considerations. The exposure to O2 results in a two stage oxidation of the Ti ingredient, which first converts into a divalent TiO (up to exposures of about 2 L), then proceeds into a tetravalent TiO2 form. Unlike oxygen, water exposure produces only the divalent oxide through the whole exposure range studied (11 L). The Mn component in these compounds is oxidized only by O2 and not by H2O. The Fe ingredient is not oxidized at all and remains in its metallic form up to exposures of 30 L.