Effect of Pulsed Plasma Beams on the Structure and Mechanical Properties of the Surface Layer in an Inconel 718 Alloy

Russian Metallurgy (Metally). 2023. Vol. 2023. No. 7. P. 891–898.

Borovitskaya I. V., Demin A. S., Komolova O. A., Latyshev S. V., Maslyaev S. A., Mikhailova A. B., I. S. Monakhov, Morozov E. V., Pimenov V. N., G. G. Bondarenko, Gaidar A. I., Logachev I. A., Matveev E. V.

The influence of pulsed helium ion (HI) and helium plasma (HP) fluxes on an Inconel 718 alloy
fabricated by an additive technology via selective laser melting and subsequent heat treatment is studied. The
structural changes in the surface layer (SL) after irradiation are analyzed for two different modes: soft (at radiation
power density q = 2 × 108 W/cm2 and pulse duration τ = 50 ns) and hard (at q = 1.5 × 109 W/cm2, τ =
25 ns). The number of pulses in each mode is N = 10 and 20. Both before and after irradiation, the structure
of the alloy is found to be a single-phase solid solution based on nickel with an fcc lattice. The action of pulsed
HI and HP fluxes on the alloy changes its texture from initial 220 to the 111 direction. This texture change
promotes plastic deformation in the irradiated SL. During this process, slip occurs primarily along the {111}
planes in fcc metals subjected to thermal stresses. The irradiation conditions affect the lattice parameters of
the alloy. Soft HI and HP irradiation reduces lattice parameter a as compared to the initial value, which can
be caused by residual macrostresses and the evaporation of impurity atoms located in interstitial lattice sites
from SL. Hard mode irradiation increases parameter a mainly due to the influence of helium ion implantation,
which promotes its growth. The observed structural changes in the SL of the alloy are shown to decrease
the microhardness and to soften the remelted layer. A numerical simulation is used to estimate the role of
thermal and shock-wave effects in the plastic deformation and the structural changes in SL under the applied
irradiation conditions.

Keywords: структура, плазма, plasma, structure, сплав Инконель, Inconel alloy