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)Ti3Al3 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 mu m) and the coherent spherical gamma' precipitates (10100 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. (C) 2022 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.