Probing the High-Entropy Concept Through the Irradiation Response of Near-Equimolar (CrNbTaTiW)C Ceramic Coatings

High-entropy ceramics have been studied as potential candidates for applications in extreme environments, such as nuclear fusion reactors. Their beneficial properties and increased radiation tolerance are often attributed to their compositional complexity achieved through equimolarity. A near-equimolar (CrNbTaTiW)C carbide, obtained by magnetron sputtering, was investigated using in situ TEM whilst being exposed to 300-keV Xe heavy ion irradiation at 573 K. The material did not show structural changes or amorphisation after irradiation to 8.5 dpa. The pristine material showed partial elemental segregation of Cr and Ti and after irradiation redistribution and homogenisation of the solid solution was observed. Furthermore, the coating showed signs of erosion damage near the surface and along some of the grain boundaries, likely due to sputtering during the energetic particle bombardment. This work suggests the response to irradiation in these novel multicomponent ceramics to be multifaceted—determined by an interplay of composition, microstructure, and constituent elements’ chemistry—going beyond simply equimolarity.