Structure and Properties of Al-Co-Cr-Fe-Ni High-Entropy Alloy Subjected to Electron–Ion Plasma Treatment

Abstract

High-entropy alloys (HEAs) are a new class of materials consisting of at least five elements in equiatomic or near-equiatomic ratio. HEAs are subjected to various types of surface treatment to improve their properties. One of the most promising methods of surface hardening is electron beam processing. This study aims to examine the structure, elemental, and phase composition of the AlCrFeCoNi HEA surface layer after the deposition of a (B + Cr) film and irradiation with a pulsed electron beam. HEA samples of non-equiatomic composition (33.4 Al; 8.3 Cr; 17.1 Fe; 5.4 Co; 35.7 Ni, at. %), fabricated by wire-arc additive manufacturing (WAAM), were used as study objects. Modification of the HEA surface layer was carried out by a complex method combining deposition of (B + Cr) film samples on the surface and irradiation with a pulsed electron beam in an argon medium. The mode of modification was identified. It makes it possible to increase microhardness (almost two times) and wear resistance (more than five times), reduce the friction coefficient of the HEA surface layer by 1.3 times due to the decrease in the average grain size, formation of particles of borides and oxyborides of complex elemental composition, the introduction of boron atoms into the crystal lattice of HEA.