Structure and stresses in NiCoFeCrMn high-entropy alloys irradiated with low-energy helium ions

NiCoCrFeMn and NiCoCrFe high-entropy alloys are formed by the method of arc melting and casting in a copper cell, followed by vacuum annealing at a temperature. Studies carried out by scanning electron microscopy and XRD analysis showed that the formed HEAs have a coarse-grained structure (80-100 μm) and are single-phase substitutional solid solutions with an fcc lattice. High-entropy alloys were irradiated at room temperature with He ions with the energy of 40 keV at fluences from 3×10¹⁷ to 5×10¹⁷ cm^-2 cm². It was found that irradiation with helium ions does not lead to erosion of the sample surface, as well as to the decomposition of NiCoCrFeMn and NiCoCrFe solid solutions. An increase in the root-mean-square deviation and tensile stresses in the samples under irradiation with helium ions is revealed. It was found that the most radiation-resistant system is NiCoCrFeMn. (authors)