Ultrastrong and ductile (CoCrNi)94Ti3Al3 medium-entropy alloys via introducing multi-scale heterogeneous structures

The coarsening-grained single-phase face-centered cubic (fcc) medium-entropy alloys (MEAs) normally exhibit insufficient strength for some engineering applications.Here, superior mechanical properties with ultimate tensile strength of 1.6 GPa and fracture strain of 13.1% at ambient temperature have been achieved in a (CoCrNi) 94 Ti 3 Al 3 MEA by carefully architecting the multi-scale heterogeneous structures.Electron microscopy characterization indicates that the superior mechanical properties mainly originated from the favorable heterogeneous fcc matrix (1-40 µm) and coherent spherical γ' precipitate (10-100 nm), together with a high number density of crystalline defects (2-10 nm), including dislocations, small stacking faults, Lomer-Cottrell locks, and ultrafine deformation twins.