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Fabrication of high-entropy alloys (HEAs) is a crucial area of interest for materials scientists since these metallic materials may have many practical uses. Wire arc additive manufacturing (WAAM), unlike other additive technologies, has tangible benefits for making large-sized components, but manufacturing the wire from HEAs is still very limited. Recent studies suggested tackling this problem using a combined cable composed of wires consisting of pure elements as feeding material. However, not all compositions of HEAs can be obtained by the pure elements’ wires because the number of them is limited. This study aims to examine phase composition, chemical elements distribution, microstructure, and mechanical properties of a Co-Cr-Fe-Mn-Ni HEA, which was not previously obtained by the WAAM. The cable-type wire used in this study is composed of two wires which consist of Cr, Fe, Mn, and Ni, and one pure Co wire. The phase composition, chemical elements distribution, microstructure, and mechanical properties were investigated. The prepared high-entropy alloy has non-equiatomic chemical composition with a single-phase FCC crystal structure with homogeneously distributed elements inside the grains. The microstructure examinations showed dendrite structure which is typical for WAAM processes. The compressive yield strength of the alloy is ~279 MPa, the ultimate compressive strength is ~1689 MPa, the elongation is 63%, and the microhardness is ~150 HV, which was found to be similar to the previously fabricated Co-Cr-Fe-Mn-Ni alloys by other methods. Fracture analysis confirmed the ductile behavior of deformation by the presence of dimples.

MoDification of strUctUre anD sUrface ProPerties of hyPoeUtectic silUMin By intense PUlse electron BeaMs Methods of contemporary physical materials science are applied for the analysis of structural and phase states, tribological and mechanical properties of hypoeutectic silumin treated by electron beams with parameters as follow: energy density-10-35 j/cm 2 , pulse duration-10 µs, number of pulses-3, pulse-repetition frequency-0.3 Hz. The initial structure of silumin comprises grains of aluminiumbased solid solution, eutectic grains, inclusions of silicon and intermetallic compounds with different shapes and sizes. Electron beam treatment (EBT) with energy density of 20-35 j/cm 2 causes melting of the surface layer, dissolution of silicon in clusions and intermetallic compounds. A structure of high-speed cellular crystallization is formed, and submicro-and nanosize particles of the second phase are reprecipitated. An average size of crystallization cells are of 0.3-0.5 µm at the irradiated surface and of 0.4-0.8 µm on the lower edge of the layer with the cellular structure. The graded structure and phase states are analysed at a depth of up to 120 µm. The submicron grains of lamellar eutectic are detected at a depth of 15 µm. The lateral sizes of eutectic lamellae are within the range of 25-50 nm. The study indicates that nanohardness of irradiated silumin changes nonmonotonously and reaches its maximum at a depth of about 30 µm, which is approximately four times higher than hardness in the initial state. Hardness of the layer close to the irradiated surface (that is at a depth of ≈ 5 µm) is higher by a factor of ≈ 1.6 than that of

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