High-entropy alloys al-co-cr-fe-mn-ni-si-v in as-cast and splat-quenched states

This work is dedicated to establish the effects of the composition and the melt cooling rate on microhardness, phase composition and parameters of the fine structure of high-entropy alloys (HEA) of Al-Co-Cr-Fe-Mn-Ni-Si-V system in the ascast and rapid quenched state. Metodology. As-cast alloy samples were obtained using a copper mold (cooling rate ~ 10 2 K/s). Quenching from a liquid state was carried out by a known technique of splat-quenching (SQ). Cooling rate estimated by foil thickness was ~ 10 6K/s. The X-ray diffraction analysis was carried out with use of the DRON-2.0 diffractometer. Microhardness was measured on the PMT-3 microhardnessmeter. Selection of components of the studied HEAs was carried out on the basis of the criteria adopted in the literature for the HEA composition based on calculation of the entropy and enthalpy of mixing, valence electron concentrations as well as the difference between the atomic radii of the components. Findings. It was found that the as-cast alloys show a multiphase BCC+B2 structure, while the SQ alloys - fully disordered BCC crystal structure only. The value of lattice parameters of the investigated alloys suggests that the solid solutions are form on the base of Cr lattice, in view of its higher melting temperature. All of the as-cast alloys display a typical cast dendritic structure with various configurations and volumes of the interdendritic space. The positive influence of microstrains level and dislocation density on the microhardness values of splatquenched Al-Co-Cr-Fe-Mn-Ni-Si-V alloys has been established. Improved mechanical characteristics are ensured by the strong distortion of the crystal lattice due to the differences in atomic radii of the elements. It was found that the splat-quenching HEAs of Al-Co-Cr-Fe-Mn-Ni-Si-V system are characterized by higher values of microhardness than as-cast alloys. Originality. At present work were first obtained and studied HEAs of Al-Co-Cr-Fe-Mn-Ni-Si-V system in the as-cast and splat-quenched state. Practical value. The HEAs possess many attractive properties, such as high hardness, outstanding wear resistance, irradiation resistance, excellent high-temperature strength, good thermal stability and corrosion resistance. The study of thin films obtained by splatquenching from the liquid state is also of great practical interest, since one of the promising applications of HEAs are thin film coatings.