Study of Structure and mechanical properties of high-entropy coating of the Al – Ni – Co – Fe – Cr system formed by microplasma spraying

High-entropy alloys (HEAs) are a new class of materials for which powder metallurgy methods (coating deposition, additive manufacturing, free sintering) are the most promising for obtaining a homogeneous structure throughout the volume of large-sized products due to the complexity of their fabrication. This paper presents the results of a study on the structure and mechanical properties of an Al – Ni – Co – Fe – Cr HEA system using the nanoindentation method. The phase composition, morphology, and mechanical characteristics of an HEA coating formed by microplasma spraying were analyzed. The structural constituents of the coating were determined by X-ray diffractometry. The hardness within each structural constituent was evaluated under a load of 5 mN. X-ray structural analysis revealed the presence of solid solutions based on BCC and FCC lattices and an intermetallic compound with parameters close to those of AlNi. Furthermore, an additional oxide phase with a high content of Al and Cr, presumably of the spinel-type AB2O4 (A = Ni/Co/Fe, B = Al/Cr), was identified. Approximately 61% of the area is occupied by a structural constituent with a nanohardness of 10.2 GPa and a Young’s modulus of 166 GPa. The obtained results can be used in the development and improvement of wear-resistant, dispersion-strengthened microplasma coatings based on HEAs.