In this work, we study the effect of low-energy bombardment by inert gas (Ar) ions on the kinetics of the initial stages of oxidation and passivation of the surface of amorphous iron-based compositions Fe$_{80}$В$_{20}$, Fe$_{40}$Ni$_{40}$P$_{16}$B$_4$, Fe$_{75}$Cr$_5$P$_{13}$C$_7$. Samples are bombarded by Аr$^+$ ions (5 keV) with doses of 10$^{15}$, 10$^{16}$, 10$^{17}$ ion/cm$^2$. The Auger electron spectroscopy method is used to study the kinetics of the oxygen adsorption and the initial stage of oxidation, depending on the value of exposure of oxygen and of the ion irradiation dose. A change in kinetics is associated with the formation, concentration, and distribution of radiation defects. In this case, the passivation effect is explained by the blocking effect of the introduced ions Ar due to the decreasing the number of both chemisorption centres and penetration places for oxygen atoms.