EFFECT OF ELECTRON-BEAM TREATMENT OF «FOIL (B+Cr) – SUBSTRATE (AlCrFe-CoNi HIGH ENTROPY ALLOY)»

10.25712/ASTU.1811-1416.2022.03.007

Abstract

Film coatings for high entropy alloys (HEA) are one of the last decade's promising and most studied objects. The AlCrFeCoNi WEC is prepared with a wire-arc additive production: a non-equivalent composition on which a B+Cr film of ~ 1 μm thickness was applied by plasma-assisted HF spraying. The subsequent treatment consisted of electron beam irradiation of the surface with parameters: energy density 20-40 J/cm², pulse duration       200 μs, frequency 0.3 s^-1, pulse number 3. The study of elemental and phase composition, condition of the defective substructure of system «film-substrate», tribological and mechanical properties were carried out by modern methods of physical materials science. There is a quasi-periodic distribution of chemical elements (at. %) 33.4 Al; 8.3 Cr;      17.1 Fe; 5.4 Co; 35.7 Ni. It is shown that at the energy density of electron beam E_s=20 J/cm² the microhardness increases by 2 times, the wear resistance is 5 times, and the coefficient of friction is reduced by 1.3 times. A mesh of microfractures fragments the surface with fragment sizes of 40-200 μm energy density At E_s=20 J/cm². High-speed crystallization of the surface layer leads to forming a subgrain structure with subgrain sizes (150-200 nm). The increase of strength and tribological properties in electron beam processing is interpreted by taking into account the reduction of grain size, the formation of chromium and aluminium oxides, the formation of a solid solution of boron introduction into the crystal grid of the wind farm.