Microstructure characterization and mechanical properties of AB-typed high-entropy intermetallics with high strength and thermal stability

In this work, we developed a new system of AB-typed high-entropy intermetallics (HEIs) based on CoHf-like B2 crystal structure. The microstructure and mechanical properties of the targeted CoxCuxTiZrHf alloys were detailedly investigated. With the increase of CoCu content, the alloys’ structure changes from multiphase to single phase. In particular, the multi-principal Co1.7Cu1.7TiZrHf alloy with single B2 crystal structure shows ultrahigh compressive yield strength of 1.77 Gpa and fracture strength of 2.15 Gpa at room temperature, as well as high elastic strain limit of approximately 1.5%. Moreover, it can maintain single-phase B2 structure and high strength after annealing at 900 °C.