Modification of the Surface Layers of Magnesium under the Action of a High-Power Ion Beam

The effect of a high-power ion beam (HPIB) of nanosecond duration on polycrystalline magnesium is investigated. A decrease in the content of magnesium oxide on the surface is found with an increase in the current density of the ion beam and the number of pulses. At a current density of 150 A/cm 2 , oxide is found only at the edges of crater formations. The observed cracks in the crater zone indicate the achievement of critical values of residual stresses under the irradiation modes used in the experiment. The analysis of changes in the grain structure show that irradiation with a HPIB leads to a decrease in the grain size by a factor of 1.6. An increase in the microhardness values is observed for magnesium samples irradiated by a HPIB with a current density of 50 and 100 A/cm 2 by three pulses by 1.3 and 1.4 times, respectively, for an indenter penetration depth of up to 6 μm and a current density of 100 A/cm 2 at large depths by 1.6 times. Two characteristic maxima of microhardness are found at depths of ~6 and ~9 µm for magnesium samples irradiated with a HPIB with a current density of 150 A/cm 2 by three pulses. Possible mechanisms for the refinement of the grain structure and changes in the microhardness in magnesium upon HPIB irradiation are discussed.