Anomalous size effect in micron-scale CoCrNi medium-entropy alloy wire

Micron-sized CoCrNi medium-entropy alloy (MEA) wires are successfully fabricated by Taylor-Ulitovsky method for the first time. The of two different sizes, with diameters 40 and 100 microns, exhibit an excellent combination tensile strength ductility. In-depth microstructure characterization indicates superior mechanical properties stem from synergy Lomer-Cottrell locks, nano-twinning HCP stacking. Surprisingly, anomalous size effect is presented in tension these microwires, i.e., much higher ductility observed micron-wire, sharp contrast to conventional single-principal element alloys only showing negligibly minor effect. Much density geometrically necessary dislocation accompanying heterogeneous deformation leading a high strain gradient, which turn joined multiple twins giving rise micron-wire.