Microstructure and tensile strength of electrodeposited Fe-rich bcc FeCoNi medium-entropy alloys

Abstract

Crystal grain refinement in high- and medium-entropy alloys is an effective approach to obtaining good strength as well as ductility. An FeCoNi medium-entropy alloy with a wide range of grain sizes was fabricated by electrodeposition. The alloy had a metastable bcc structure with Fe–36 at.% Co–21 at.% Ni composition and heterogeneous distribution of grain sizes ranging from 20 nm to 15 µm. Moreover, the alloy possessed a tensile strength of 1.2 GPa, and a fracture elongation of 6.3 % without secondary phase. The excellent mechanical properties of the alloy can be attributed to its bcc phase and heterogeneous grain sizes extending to the nanoscale.