Effect of Pulsed-Electron-Beam Irradiation on the Surface Structure of a Non-Equiatomic High-Entropy Alloy of the Al–Co–Cr–Fe–Ni System

In this work, an electron microscopic study of the surface of a high-entropy alloy (HEA) of the Al–Co–Cr–Fe–Ni system obtained by wire-arc additive manufacturing and modified with a pulsed electron beam is performed. It is shown that the alloy is a polycrystalline aggregate with a grain size of (4–15) µm and has a non-equiatomic composition with a high content of Al and Ni. It is established that the boundary volumes of the alloy (volumes located along the grain boundaries) are enriched with chromium and iron atoms, the grain volume is enriched with Ni and Al atoms, and Co is distributed in the alloy quasi-uniformly. It is shown that irradiation with a pulsed electron beam leads to fragmentation of the surface layer of the samples by microcracks; it is accompanied by homogenization of the surface layer and the formation of a submicro-nanocrystalline (100–200 nm) structure. There is no change found in the elemental composition of the HEA-sample surface layer after irradiation in vacuum with a pulsed electron beam (200 µs, (10–30) J/cm2, 3 pulses).