Preparation of nanoporous CoCr alloy by dealloying CrCoNi medium entropy alloys

High/Medium entropy alloys (H/MEAs) represent a new strategy for the design of materials with properties superior to those of conventional alloys. Here, we show a new field of application where the uniform mixtures of multiple principal elements in H/MEAs is utilized to create new type nanoporous alloys by dealloying. By using equiatomic CrCoNi MEAs as a proto-type system, we developed three-dimensional bi-continuous open nanoporous CoCr alloys composed of single-phase solid-solution with equiatomic ratios by liquid-metal dealloying methods. The morphology and size of ligaments and pores could be tailored by controlling dealloying time. Structural evolution of the nanoporous CoCr alloy during dealloying can be well described by surface smoothening and ligament pinch-off mediated coarsening process. This study opens up a new promising pathway for development of new type nanoporous alloys-nanoporous high entropy alloys, which are expected to have unprecedented structural and functional properties due to a unique synergistic combination of nanoporous structure and high-entropy effect.