Nanostructured intermetallics prepared by dealloying from single crystal nickel-based superalloys

Two-nanostructure intermetallics (nanoporous film and nanocube) on single crystal nickel-based superalloys were fabricated by electrochemical dealloying in an aqueous electrolyte containing 1 wt% (NH4)2SO4 and 1 wt% citric acid solution respectively. Electrochemical properties of two phases in single crystal nickel-based superalloys are different, and it has been utilized to dissolve preferentially γ matrix phase and γ′ phase remains passive. The electrochemical corrosion behavior of a Ni-based superalloy after high temperature creep was investigated using an EG&G PAR M273 potentiostat. The results indicated that the microstructure after high temperature creep determined the morphology of the resultant γ′ phase intermetallics after dealloying. The morphologies and structure of nanoporous film and nanocube were characterized using a JSM-6700 (Japan) field emission scanning electron microscope (FE-SEM) and JEM-3010 high resolution transmission electron microscopy (HRTEM).