Synthesis and Irradiation response of high entropy alloys with transition and refractory metals for operation at extremes

High-entropy alloys (HEAs) are a class of materials which have been intensely studied during the last years due to their innovative properties. However, their unconventional compositions and chemical structures hold promise for achieving unprecedented combinations of mechanical properties, microstrutures and irradiation resistance for use in extreme environments. In this work results on two types of HEAs will be presented: based on transition metals (CuCrFeTiV) and refractory metals (CrNbTaVW). All the alloys were prepared by ball milling followed by consolidation by spark plasma sintering and then irradiated with Ar ions in order to check the adequacy for use as a thermal barrier in future nuclear fusion reactors. Structural changes were investigated by X-ray diffraction, and scanning electron microscopy and scanning transmission electron microscopy, both coupled with X-ray energy dispersive spectroscopy. Surface irradiation damage on CuCrFeTiV was detected for high fluences (31018 Ar+/cm2) with the formation of blisters of up to 1 m in diameter. Cross-sectional scanning transmission electron microscopy showed the presence of intergranular cavities only in the sample irradiated with 31018 Ar+/cm2, while all irradiation experiments produced intragranular nanometric-sized bubbles with increased density for higher Ar+ fluence. Moreover, no severe superficial modifications were observed in the CrNbTaVW samples, after irradiation at different temperatures.