The Effect of Irradiation with a High-Power Ion Beam on Atmospheric Oxidation of Polycrystalline Magnesium

Studies have been carried out of the influence of a high-power ion beam of nanosecond duration on the atmospheric oxidation of polycrystalline magnesium. A decrease in the magnesium oxide phase was detected with increasing beam current density, which is probably due to the intensification of the processes of gas-dynamic expansion of the surface. Subsequent exposure of unirradiated and irradiated samples to a high-power ion beam at a temperature of 240°C in air led to a slowdown in the growth of the oxide phase in the irradiated samples. In this case, the greatest effect was observed for samples irradiated by a beam with a current density of 150 A/cm2. The role of chemical processes, mechanical stresses, and structural changes occurring in the beam-modified zone and influencing the oxidation process is discussed. The observed nonmonotonic dependences of the ratios of oxygen and carbon concentrations to magnesium for different heating times are explained by the formation of not only magnesium oxide but also probably magnesium hydroxide and carbonate. It has been shown that the effect of increasing the oxidation resistance of magnesium irradiated with a high-power ion beam can also be influenced by an increase in the concentration of carbon during its penetration into the surface layer.