Abstract
In this study, radiation-induced segregation was studied in high-entropy alloys (HEA) CoCrFeNi, CoCrFeMnNi, irradiated with helium ions He2+ with an energy of 40 keV at room temperature. Changes in the concentrations of HEAs and their depth distributions were studied by Rutherford Backscattering (RBS) and energy dispersive x-ray spectroscopy (EDS) methods. Measurements using the RBS and EDS methods showed that non-irradiated HEAs have a composition close to equiatomic, where the average concentration for CoCrFeNi is 24.8 atomic percents (at.%), and for CoCrFeMnNi – 20 at.%. The EDS results were significantly different from the RBS in Ni/Co concentrations, and indicated no significant changes in element distribution in both HEAs after irradiation. According to the RBS data, the largest changes in concentrations during irradiation in both HEAs relate to the enrichment of Ni atoms. In CoCrFeNi, upon irradiation, Ni/Co atoms undergo the greatest segregation, and in CoCrFeMnNi, the Ni/Co/Fe concentrations change significantly. In CoCrFeMnNi, the change in element concentrations with increasing irradiation fluence was more pronounced than in CoCrFeNi. In CoCrFeMnNi, changes in concentrations of all elements at both fluences reached 0.5–17% (0.1–3.1 at.%) and exceeded changes in CoCrFeNi, which reached 2–11% (0.5–1.9 at.%). It was found that the resistance to segregation when irradiated with helium ions under these conditions was lower for CoCrFeMnNi than for CoCrFeNi. In CoCrFeNi and CoCrFeMnNi, changes in the concentrations of Co, Fe, Cr, and Mn were significantly less than changes near sinks and defect clusters when irradiated with nickel ions with similar doses in other studies at temperatures close to the halfmelting temperature of nickel HEAs. The RBS study showed a uniform distribution of atoms in depth and resistance to segregation in CoCrFeNi, CoCrFeMnNi when irradiated with helium ions.