Single-step electrochemical synthesis of nano-crystalline CoCrFeNi high-entropy alloy powder

The difficulty of producing high-entropy alloy (HEA) powders is one of the key issues that limits the application of HEAs in a range of fields, including energy devices, additive manufacturing and spraying techniques. In the present work, nano-size equiatomic CoCrFeNi HEA powder has been prepared from micro-size mixed metal-oxide precursors by electro-deoxidation in molten CaCl2-NaCl at 923 K. The HEA powder obtained had a single-phase face-centered cubic structure with a lattice constant of 3.571 Å, and was of a powdery morphology with spherical particles in the size range of 40–200 nm. The composition achieved was close to the nominal one and no contamination was detected. Altogether, this study has demonstrated that, with suitably adjusted process parameters, electro-deoxidation is an effective method of producing nano-size HEA powders.