Characteristics of plastically deformed fcc and bcc High-Entropy Alloys

High-Entropy Alloys (HEAs) are alloys with at least four principal elements in (near-)equiatomic proportion, which crystallize on simple crystal lattices, such as face-centred cubic, bodycentred cubic, or hexagonal close-packed. These alloys have a stoichiometrically random distribution of constituent elements on all available lattice sites, and they formsingle-phase solid solutions with perfect topological order and complete chemical disorder. The structural simplicity of HEAs makes them well-suited to address fundamental scientific issues related to structure-property relationships. In this work, the plasticity of two HEAs, face-centred cubic CrMnFeCoNi and body-centred cubic TiVZrNbHf, was investigated through uniaxial deformation experiments on single crystalline CrMnFeCoNi and polycrystalline TiVZrNbHf samples. The thermodynamic activation parameters of the reformation process were determined, andmicrostructural investigations were carried out on both alloys using transmission electron microscopy. These investigations revealed the underlying deformation mechanisms of both alloys. Although both alloys deformthrough the slip of dislocations on characteristic slip systems, CrMnFeCoNi behaves like a conventional face-centred cubic alloy with exceptional strength, while TiVZrNbHf exhibits a yield stress anomaly that is unique to HEAs.