Damage to the Surface Layer of Inconel 718 Alloy by Pulsed Beam-Plasma Flows

Damage to the surface layer of the Inconel 718 alloy, manufactured by selective laser melting using additive technology followed by heat treatment, is studied under conditions of repeated pulsed exposure to flows of helium ions and helium plasma under two irradiation modes in the Vikhr Plasma Focus installation: in a soft mode with energy flux density q(0) = 2 x 108 W/cm(2) and pulse duration tau = 50 ns and in a hard mode with q(0) = 1.5 x 109 W/cm(2) and tau = 25 ns. The number of pulses in the experiments was N = 10 and 20. Irradiation in a soft mode forms a microstructure containing pores on the layer surface, and with more severe energy exposure, surface microcracks and blisters with destroyed shells are formed. With an increase in the energy flux density, the surface layer erosion intensity (mass loss per pulse) increased. The nature of this phenomenon is determined by the processes of cleaning the surface layer of an alloy from impurity elements adsorbed from the external environment before irradiation, as well as the deposition of elements of functional materials and working gas impurities on the irradiated surface. Features of cellular microstructure formation of the surface layer (SL) of an alloy under study under the realized conditions of beam-plasma influences have been revealed. Using the numerical modeling method, the redistribution of the shares of energy absorbed by the material, spent on evaporation and melting of the irradiated surface layer (SL), in comparable irradiation modes was established.